Sponsors - University of Colorado Boulder program.pdfAdvanced Materials and Liquid Crystal Institute, Kent State University, USA 3D liquid crystal elastomers as long term responsive

FLC2019.COLORADO.EDU

The 17th International Ferroelectric Liquid Crystal Conference will feature oral and poster presentations in all areas involving chirality and polarity in soft matter.

Design and synthesis of novel FLC materials The twist-bend phases Twist grain boundary phases Fluid ferroelectrics and ferromagnetics Advances in resonant X-ray scattering LCs and biology Blue phases Industrial applications Spontaneous achiral symmetry breaking (chiral self-assembly of achiral molecules)

Major Themes

Sponsors

The organizers gratefully acknowledge major financial support from Vvi Bright China

http://flc2019.colorado.edu

http://flc2019.colorado.edu

Sunday, August 4, 20194:00 PM Registration - WeatherTech Cafe, C4C6:00 PM Reception - WeatherTech Cafe, C4C

Monday, August 5, 20198:45 AM Dave Walba, Conference Chair

Department of Chemistry, University of Colorado Boulder, USAOpening remarks

Session 1Chair:

Dave Walba

9:00 AM Plenary 1: Corrie ImrieDepartment of Chemistry, Aberdeen University, United KingdomThe twist-bend nematic phase

9:45 AM Invited 1: Dmitry Bedrov Department of Materials Science and Engineering, University of Utah, USAIn-silico characterization of CB7CB twist-bend nematic phase

10:15 AM Oral 1: Jiale Shi Department of Chemical and Biomolecular Engineering, University of Notre Dame, USANovel elastic response in twist-bend nematic models

10:35 AM Coffee Break11:00 AM Invited 2: Georg Mehl

Department of Chemistry and Biochemistry, University of Hull, United Kingdom Investigation of materials with two nematic phases

Session 2Chair:

Ewa Gorecka

11:30 AM Oral 2: Karl Saunders Department of Physics, Cal Poly San Luis Obispo, USAA new twist on the electroclinic critical point: type I and type II smectic C* systems

11:50 AM Oral 3: Noel Clark Department of Physics, University of Colorado Boulder, USAMolecular correlations, fluctuations, and order in the twist-bend phase

12:10 PM Lunch2:00 PM Plenary 2: Oleg Lavrentovich

Advanced Materials and Liquid Crystal Institute, Kent State University, USAElectrically driven dynamic three-dimensional solitons in nematic liquid crystals

Session 3Chair:

Corrie Imrie

2:45 PM Invited 3: Alexey Eremin Department of Nonlinear Phenomena, Institute for Physics, Otto von Guericke University, GermanyPhoto-switchable bent-core liquid crystals

3:15 PM Oral 4: Piotr Kaszyński Faculty of Chemistry, University of Łódź, PolandParamagnetic antiferroelectrics: bent-core mesogens derived from the Blatter radical

3:35 PM Oral 5: Rafaela Raupp da Rosa Chemistry Institute, Universidade Federal do Rio Grande do Sul, Brazil Isoxazolines as novel building blocks for polar smectic phases

3:55 PM Coffee Break4:25 PM Invited 4: Jun Yamamoto

Department of Physics, Graduate School of Science, Kyoto University, Japan Fast response and low driving voltage DH-FLC mode of SmC* on the slippery interfaces

Session 4Chair:

Noel Clark

4:55 PM Oral 6: Sidra Khan Department of Physics, Aligarh Muslim University, IndiaCriticality of pitch for the observation of partially unwound helical mode in ferroelectric liquid crystals

5:15 PM Oral 7: Ye Yuan Department of Physics, University of Colorado Boulder, USA Stimuli-responsive mesostructured hybrid materials

5:35 PM Poster Session 1 - Odd numbered posters7:30 PM Free Evening

Tuesday, August 6, 20199:00 AM Plenary 3: Ewa Gorecka

Faculty of Chemistry, University of Warsaw, Poland Complex helicoidal structure of layered phases made of achiral molecules

Session 5Chair:

Oleg Lavrentovich

9:45 AM Invited 5: Yoichi Takanishi Graduate School of Science, Kyoto University, JapanStructure analysis of electric-field-induced chiral smectic liquid crystalline phases by microbeam resonant X-ray scattering

10:15 AM Oral 8: Adam Green Department of Physics, University of Colorado Boulder, USAActivated chirality of bent-core achiral smectics

10:35 AM Coffee Break11:00 AM Invited 6: Chenhui Zhu

Advanced Light Source, Lawrence Berkeley National Laboratory, USAResonant soft and tender X-ray scattering of liquid crystal phases: the past and future

Session 6Chair:

Frank Giesselmann

11:30 AM Oral 9: Torsten Hegmann Advanced Materials and Liquid Crystal Institute, Kent State University, USAFine-tuning of the highly sensitive chirality amplification through space of chiral ligand-capped nanomaterials visualized in the induced cholesteric phase

11:50 AM Oral 10: Tim White Department of Chemical and Biological Engineering, University of Colorado Boulder, USAExploiting directed self-assembly to enable functional performance in liquid crystalline elastomers

12:10 PM Lunch2:00 PM Plenary 4: Alenka Mertelj

Jožef Stefan Institute, Ljubljana, Slovenia Splay nematic phase

Session 7Chair:

Yoichi Takanishi

2:45 PM Invited 7: Lech Longa Marian Smoluchowski Institute of Physics, Jagiellonian University, Poland Nematic twist-bend phase in an external field

3:15 PM Oral 11: Jae-Jin Lee Department of Advance Materials Engineering for Information and Electronics, Kyung Hee University, KoreaChirality imprinting from chiral superstructures formed by achiral molecules to achiral mesogens

3:35 PM Oral 12: Martin Čopič Jožef Stefan Institute, Ljubljana, Slovenia Q-tensor model of twist-bend and splay nematic phases

3:55 PM Coffee Break4:25 PM Invited 8: Fumito Araoka

RIKEN Center for Emergent Matter Science, Japan Shifted photocurrent in a polar columnar liquid crystal

Session 8Chair:

Antal Jákli

4:55 PM Oral 13: Robert Lemieux Department of Chemistry, University of Waterloo, Canada The effect of an ethynyl spacer on mesomorphic and ‘de Vries-like’ properties of tricarbosilane mesogens

5:15 PM Oral 14: Greg Smith Department of Physics, University of Colorado Boulder, USA Exploration of short-oligomer nucleic acid liquid crystals

5:35 PM Poster Session 2 - Even numbered posters7:30 PM Free Evening

Wednesday, August 7, 20199:00 AM Plenary 5: Frank Giesselmann

Institute of Physical Chemistry, University of Stuttgart, Germany New aspects of chirality in lyotropic liquid crystals

Session 9Chair:

Matt Glaser

9:45 AM Invited 9: Alberta Ferrarini Department of Chemical Sciences, University of Padova, ItalyChirality propagation in liquid crystalline phospholipid membranes

10:15 AM Oral 15: Elda Hegmann Advanced Materials and Liquid Crystal Institute, Kent State University, USA3D liquid crystal elastomers as long term responsive scaffolds for tissue regeneration

10:35 AM Coffee Break11:00 AM Invited 10: Zhengdong Cheng

Artie McFerrin Department of Chemical Engineering, Texas A&M University, USA Nanoplate liquid crystals in external fields

Session 10Chair:

Alenka Mertelj

11:30 AM Oral 16: Min Shuai Department of Physics, University of Colorado Boulder, USADroplets of ferromagnetic nematic colloidal liquid crystal

11:50 AM Oral 17: Jonathan Selinger Department of Physics, Kent State University, USA Interpretation of saddle-splay and the Oseen-Frank free energy in liquid crystals

12:10 PM Lunch2:00 PM Plenary 6: Carsten Tschierske

Department of Chemistry, Martin-Luther University Halle-Wittenberg, Germany Oxadiazoles and 4-cyanoresorcinols – insights into the development of polarity and chirality

Session 11Chair:

Eva Korblova

2:45 PM Invited 11: Goran Ungar State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, China Cubic and other 3D phases from interlocking twisted ribbons

3:15 PM Oral 18: William Thurmes Miyota Development Center of America, Longmont, CO, USAA database for liquid crystal mixture formulation

3:35 PM Oral 19: Brian Donovan Department of Chemical and Biological Engineering, University of Colorado Boulder, USA Mechanotropic elastomers

3:55 PM Coffee Break4:25 PM Invited 12: Antal Jákli

Physics Department, Kent State University, USA Oligomeric odd-even effect in liquid crystals

Session 12Chair:

Joe Maclennan4:55 PM Open Discussion Future prospects for ferroelectric liquid crystals and chiral/polar soft matter

5:35 PM Closing Remarks7:30 PM Banquet - Millenium Harvest House

Posters Page 1

Poster Presentations Posters will be on display for the duration of the conference. Odd numbered posters should be presented during the poster session on Monday, even numbered posters on Tuesday.

Poster 1: Vladyslav Cherpak University of Colorado Boulder, USA Developing liquid crystalline aerogels for thermal insulation of buildings

Poster 2: Hyeon-Joon Choi Kyung Hee University, South Korea Mirrorless lasing from three-dimensional photonic liquid crystalline blue phase II

Poster 3: Nathan Cobasko University of Colorado Boulder, USA Fréedericksz transition in ferromagnetic nematic filaments

Poster 4: Hayden Elise Fowler University of Colorado Boulder, USA Localizing genesis in polydomain liquid crystal elastomers

Poster 5: Antal Jákli Kent State University, USA Fast electro-optical switching of dichroic dye-doped antiferroelectric liquid crystals without polarizers

Poster 6: Piotr Kaszynski Middle Tennessee State University, USA Electrooptical characterization of zwitterionic derivatives of [closo-CB9H10]

Poster 7: Eva Korblova University of Colorado Boulder, USA Novel nanofilament phase formed by carbosilane terminated bent-core mesogens

Poster 8: Akihiro Mochizuki i-CORE Technology, USA Consideration of distorted in-plane and out-of-plane retardation switching on certain types of smectic liquid crystals

Poster 9: John Papaioannou University of Colorado Boulder, USA Simulation studies of ferromagnetic nematic fluids

Poster 10: Damian Pociecha University of Warsaw, Poland Multi-level chirality in smectic phases made of achiral dimeric molecules

Posters Page 2

Poster 11: Brian Radka University of Colorado Boulder, USA Towards elucidating the electrochemical interaction of ions and structurally chiral polymer stabilized networks in electrically tunable filters

Poster 12: Zbigniew Raszewski Military University of Technology, Poland Investigation of the relationships between spontaneous polarization and tilt angle in ferroelectric and antiferroelectric liquid crystals

Poster 13: Eric A Scharrer University of Puget Sound, USA Investigations of oxadiazole-based bent-core liquid crystals containing strongly polar lateral groups

Poster 14: Kyle Schlafmann University of Colorado Boulder, USA Color reconfiguration in liquid crystalline elastomers

Poster 15: Bohdan Senyuk University of Colorado Boulder, USA Elastic and electrostatic multipoles in liquid crystals

Poster 16: Harpreet Singh Slides University, India Properties of nanodoped surface stabilized ferroelectric liquid crystals under electric and magnetic fields

Poster 17: Greg Smith University of Colorado Boulder, USA Intricate behavior of 4-base nanoDNA sequences: an intersection between condensed matter and RNA world

Poster 18: Yoichi Takanishi Kyoto University, Japan Improvement of electro-optical response of vertical aligned ferroelectric liquid crystals

Poster 19: William Thurmes Miyota Development Center of America, USA Development of bistable ferroelectric liquid crystals

Poster 20: Ke-Qing Zhao Sichuan Normal University, China Polar discotic liquid crystals and semiconductivity

Poster 21: Jerzy Zieliński Military University of Technology, Poland Chiral dopant induced properties of a working ferroelectric smectic mixtures

Plenary Abstracts

The Twist-Bend Nematic Phase

Corrie T Imrie

Department of Chemistry, University of Aberdeen, Meston Building, King’s College, Aberdeen, AB24 3UE, United Kingdom.

The discovery of a new nematic phase, the twist bend nematic phase, NTB, has caused considerable excitement [1]. In the NTB phase, the achiral molecules form a helix and the director is titled with respect to the helical axis. The induced twist may be either left or right handed and equal amounts of both types of helix are expected. The pitch of the helix is strikingly small, typically of the order of 8 nm [2]. A particularly fascinating feature of the NTB phase is the observation of spontaneous chirality even though the molecules are effectively achiral. The molecular curvature, that is essential for the formation of the NTB phase, can be realized using odd-membered liquid crystal dimers consisting of molecules containing two mesogenic units linked by a flexible spacer. Here we present a range of new liquid crystal dimers and other types of materials which exhibit the NTB phase and discuss structure-property relationships (see, for example, [3-5]). We will also consider the effect of molecular chirality on the formation of the NTB phase. Finally, we will discuss the recent observation of twist-bend smectic phases and how these relate to molecular structure [6, 7].

References

[1] M. Cestari, S. Diez-Berart, D. A. Dunmur, et al, Phys. Rev. E 84, 031704 (2011).

[2] V. Borshch, Y. K. Kim, J. Xiang, et al, Nature Commun. 4, 2635 (2013).

[3] D. A. Paterson, M. Gao, Y. K. Kim, et al, Soft Matter 12, 6827-6840 (2016).

[4] D. A. Paterson, J. P. Abberley, W. T. Harrison, et al, Liq. Cryst. 44, 127-146 (2017).

[5] R. Walker, D. Pociecha, G. Strachan, et al, Soft Matter 15, 3188-3197 (2019).

[6] J. P. Abberley, R. Killah, R. Walker, et al, Nature Commun. 9, 228 (2018).

[7] M. Salamonczyk, N. Vaupotic, D. Pociecha, et al, Nature Commun. 10, 1922 (2019). * E-mail: [email protected]

Plenary 1

Electrically driven dynamic three-dimensional solitons in nematic liquid crystals

Oleg D. Lavrentovich1,2*, Bing-Xiang Li 1, Volodymyr Borshch1, Sergij V. Shiyanovskii1 1Advanced Materials and Liquid Crystal Institute, Chemical Physics Interdisciplinary Program,

Kent State University. Kent, Ohio 44242 2Department of Physics, Kent State University. Kent, Ohio 44242

Electric-field induced collective reorientation of nematic molecules placed between two flat parallel electrodes is of importance for both fundamental science and practical applications. This reorientation is either homogeneous over the area of electrodes, as in liquid crystal displays, or periodically modulated, as in electroconvection. The question is whether the electric field can produce spatially localized solitary waves of molecular orientation. We demonstrate electrically driven three-dimensional particle-like dissipative solitons representing self-trapped waves of

oscillating director. The solitons, called the director bullets, propagate with a very high speed perpendicularly to the electric field. The propulsion is enabled by rapid reorientations of the director with the frequency of the applied alternating current electric field and by lack of fore-aft symmetry. The main mechanism of bullets formation is flexoelectricity. The solitons preserve self-trapped shapes while moving over distances hundreds of times larger than their size and survive collisions. During collisions, the solitons show mutual attraction and repulsion that depend on the impact parameter. Solitons are observed in two distinct regions of the electric field frequency regions. The high-frequency (0.1-1 kHz) solitons propagate perpendicularly to the background director [1]. The low-frequency (3-30 Hz) solitons can be steered by the electric field in the plane of the cell. The steering does not modify the properties of the background that remains uniform. The low-frequency solitary waves represent multidimensional solitons of (3+2)D type that show fore-aft and right-left asymmetry with respect to the background molecular director; the symmetry is controlled by the field. Besides bringing a fundamental novelty to the field of localized patterns, the director bullets can lead to applications such as targeted delivery of information and micro-cargo.

Acknowledgements The work was partially supported by NSF grants DMS-1729509 and DMR-1905053.

References [1] B.-X. Li, V. Borshch, R.-L. Xiao, S. Paladugu, T. Turiv, S.V. Shiyanovskii, O.D. Lavrentovich, Nature Comm. 9, 2912 (2018). * Author for Correspondence: [email protected]

Figure 1. High-frequency director bullet’s structure [1].

Plenary 2

Complex helicoidal structure of layered phases made of achiral molecules

Nataša Vaupotič,1,2 Mirosław Salamończyk,3,4 Damian Pociecha,3 Rebecca Walker,5 John M. D. Storey,5 Corrie T. Imrie,5 Cheng Wang,4 Chenhui Zhu,4 Ewa Gorecka3

1 Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia; 2Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia; 3Faculty of Chemistry, University of Warsaw, ul. Zwirki i Wigury 101, 02-089 Warsaw, Poland; 4 Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA, USA, 94720; 5 Department of

Chemistry, King’s College, University of Aberdeen, Aberdeen, AB24 3UE, UK

In many biological materials with a hierarchical structure there is an intriguing and unique

mechanism responsible for the ‘propagation’ of order from the molecular to the nano- or micro-

scale level. We show that a much simpler molecular system built of achiral mesogenic dimeric

molecules exhibits a similar complexity with four levels of structural chirality: (i) layer

chirality, (ii) nanoscopic helicity of a basic few layer repeating unit, (iii) a mesoscopic helix

and (iv) spiral nano-fibres. In some of the studied systems the nanoscopic pitch corresponds to

exactly four smectic layers. The mesoscopic pitch can be of several to hundreds of layers. We

also discuss how the molecular chirality might influence the structure, creating the second twist

leading to the TGB-type phases.

The chiral structure was studied using resonant X-ray scattering (RSoXS) at the carbon

absorption edge - a unique method sensitive not only to the electron density modulation but

also to the orientation of molecules and clearly indicated a coupling among chiralities at

different levels.

[1] [1] M. Salamończyk, N. Vaupotič, D. Pociecha, R. Walker, J. M. D. Storey, C. T. Imrie, C. Wang, C. Zhu, Ewa Gorecka, Multi-level Chirality in Liquid Crystals Formed by Achiral Molecules, Nat. Commun. 10, 922 (2019) Corresponding author: [email protected]

Plenary 3

Splay Nematic Phase A.Mertelj*1, L. Cmok1, N. Sebastián1, R. J. Mandle2, R. R. Parker2, A. C. Whitwood2, J. W.

Goodby2, and M. Čopič1 1Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia,

2Department of Chemistry, University of York, York, YO10 5DD, United Kingdom Recently designed polar, rodlike, liquid-crystalline materials exhibits two distinct nematic mesophases separated by a weakly first-order transition[1,2]. In this talk I will present a study of a transition between these nematic mesophases in one of such materials[3,4]. The high temperature phase is the ordinary nematic phase, while in the second nematic phase defect structures not present in the uniaxial nematic phase are observed. This indicates that the new phase has lower symmetry than the ordinary nematic phase. The phase transition is weakly first order, with a significant pretransitional behavior, which manifests as strong splay fluctuations. When approaching the phase transition, the splay nematic constant is unusually low and goes towards zero. Analogously to the transition from the uniaxial nematic to the twist-bend nematic phase, this transition is driven by instability towards splay orientational deformation, resulting in a periodically splayed structure. And, similarly, a Landau-de Gennes type of phenomenological theory can be used to describe the phase transition. The proposed structure of the modulated splay phase is biaxial and antiferroelectric (Figure 1).

Acknowledgements A.M., M.Č., L.C. and N.S. acknowledge financial support from the Slovenian Research Agency (Research Core Funding No. P1-0192, Project No. J7-8267). N. S. thanks the European Union’s Horizon 2020 Research and Innovation Programme for its support through the Marie Curie Individual Fellowship No. 701558 (MagNem). R. J. M. and J. W. G. acknowledge funding from EPSRC (UK) for the Bruker SAXS/SWAXS equipment via EP/K039660/1 and for ongoing work via EP/M020584/1.

References [1] R. J. Mandle, S. J. Cowling, and J. W. Goodby, Phys. Chem. Chem. Phys. 19, 11429 (2017). [2] R. J. Mandle, S. J. Cowling, and J. W. Goodby, Chem. Eur. J. 23, 14554 (2017). [3] A. Mertelj, L. Cmok, N. Sebastián, R. J. Mandle, R. R. Parker, A. C. Whitwood, J. W. Goodby and M. Čopič, Phys. Rev. X 8, 041025 (2018). [4] R. J. Mandle and A. Mertelj, preprint (2019). DOI: 10.26434/chemrxiv.8320985.v1 * Author for Correspondence: [email protected]

Figure 1. Proposed structure of the splay nematic phase.

Plenary 4

New aspects of chirality in lyotropic liquid crystals

F. Giesselmann*

Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany

Chirality in liquid crystals gives rise to a plethora of remarkable macroscopic phenomena such as the spontaneous director twist in cholesterics and blue phases or the spontaneous electric polarization in the chiral smectic C*-type family of liquid crystals. In comparison to their thermotropic counterparts, chirality effects in lyotropic liquid crystals have been less investigated so far.

This presentation will review some new aspects of chirality in lyotropics, namely the recognition of the lyotropic equivalent of the ferroelectric chiral smectic C*-phase [1], the electroclinic effect observed in chiral lamellar 𝛼𝛼-phases [2], and the formation of chiral structures in achiral lyotropic nematics under capillary confinement [3, 4]. Recent light scattering studies reveal that both chromonic and standard micellar lyotropic nematics exhibit anomalously small twist elastic moduli K2 which make these phases extremely sensitive to chiral perturbations.

Figure 1. Chiral twisted polar configuration of an achiral micellar lyotropic nematic liquid crystal confined in a cylindrical capillary. Two +1/2 twist disclination lines form a double helix along the capillary axis.

References [1] J. R. Bruckner, J. H. Porada, C. F. Dietrich, I. Dierking, and F. Giesselmann, Angew. Chem.Int. Edit. 52, 8934–8937 (2013).[2] M. D. Harjung and F. Giesselmann, Phys. Rev. E 97, 032705 (2018).[3] J. Jeong, L. Kang, Z. S. Davidson, P. J. Collings, T. C. Lubensky, and A. G. Yodh, P. Natl.Acad. Sci. USA 112, E1837–E1844 (2015).[4] C. F. Dietrich, P. Rudquist, K. Lorenz, and F. Giesselmann, Langmuir 33, 5852–5862 (2017).

* Author for Correspondence: [email protected]

Plenary 5

Oxadiazoles and 4-Cyanoresorcinols – Insights into the Development of Polarity and Chirality

C. Tschierske*1, E. Westphal1, M. Poppe1, M. Alaasar1, S. Poppe1, A. Eremin2

1Department of Chemistry, Martin-Luther University Halle-Wittenberg,06120 Halle (Saale), Germany

1Department of Physics, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany

The focus of the talk will be on molecules with a shape at the cross-over from linear to bent, which provides a series of interesting phenomena related to layer coupling, emergent polar order and concerning chirality issues.

In the first part the focus will be on the LC phases of simple 1,3,4-oxadiazole compounds and their silylated analoga. We have solved the structures of the phases previously designated as SmX, SmY and SmZ [1]. Among them there are dark conglomerate phases and it was found that the type of conglomerate structure changes from chiral SmCaPA-like for the alkylated to achiral SmCsPA-like for the silylated compounds.[2]

The focus in the second part is on the astonishing observation of polar heliconical smectic phases in the series of 4-cyanoresorcinol based bent-core molecules.[3,4] We have conducted a detailed investigation of the relations between molecular structural parameters and the capability of helix formation, showing that the transition from paraelectric to (anti)ferroelectric phases [5] takes place via heliconical phases if the tilt-correlation is weak, and for larger tilt via layer modulation.

At the end the general importance of helix formation and chirality synchronization for LC phase structures will be discussed by drawing relations to other chirality modulated LC phases, like cubics and SmQ phases of polycatenars and the chirality induced phases of permanently chiral rod-like mesogens.[6]

Acknowledgements The authors wish to thank the DFG for financial support.

References

[1] T. J. Dingemans, and E.T. Samulski, Liq. Cryst. 27, 131-136 (2000).[2] E. Westphal, H. Gallerdo, N. Sebastian, A. Eremin, M. Prehm, M. Alaasar, and C.Tschierske, J. Mater. Chem. C 7, 3064-3081 (2019).[3] S. P. Sreenilayam, Y. P. Panarin, J. K. Vij, V. P. Panov, A. Lehmann, M. Poppe, M. Prehm,and C. Tschierske, Nature Commun. 7, 11369 (2016).[4] A. A. S. Green, et al., Phys. Rev. Lett. 122, 107801 (2019).[5] N. Sebastian, S. Belau, A. Eremin, M. Alaasar, M. Prehm, and C. Tschierske, Phys. Chem.Chem. Phys. 19, 5895 (2017).[6] C. Tschierske, and G. Ungar, ChemPhysChem, 17, 9-26 (2016); C. Tschierske, Liq. Cryst.45, 2221–2252 (2018).* Author for Correspondence: [email protected]

Plenary 6

Invited Abstracts

In-Silico Characterization of CB7CB Twist-Bend Nematic Phase D. Bedrov*1, X.Wei1, J. B.Hooper1, J.Yelk2, M. Glaser2, and N. Clark2

1Department of Materials Science & Engineering, University of Utah,Salt Lake City, Utah, USA

2Department of Physics, University of Colorado- Boulder, Boulder, Colorado, USA

Extensive atomistic MD simulations of bulk CB7CB were conducted in the 330-450K temperature range to identify phase transitions and stability of the Twist Bend Nematic (TBN), Nematic (N), and Isotropic (I) phases of this material. We have successfully observed the formation of all three phases, both on coolingand heating paths. Consistent with experimental observations, the CB7CB showed a very narrowtemperature range (~10 degrees) for the stability of the N phases. MD simulation trajectories were utilizedi) to provide a detailed molecular level characterization of structural and dynamical properties (variousorder parameters, molecular translational and rotation diffusion, dynamic structure factor, and inelastic X-ray structure factor) of the TBN, N, and I phases, and ii) to determine which of those correlations areresponsible for the TBN stability and structural characteristics. For the latter, we utilize the ability of MDsimulations to straightforwardly perturb or alter certain interactions or correlations and observe theoutcome. For example, we investigated the influence of the magnitude of the dipole moment associatedwith the CB groups or conformational flexibility of biphenyl unit on the stability of CB7CB phases.Analysis of dynamical properties (e.g. self-diffusion coefficients, various molecular vectors dynamiccorrelation functions, etc.) demonstrated anisotropic dynamics both in TBN and N phases of CB7CB.

Acknowledgements This work was supported by the Soft Materials Research Center under NSF MRSEC Grants DMR-1420736. Authors also would like to acknowledge computational resources provided by the University of Utah Center for High Performance Computing.


Figure 1. Snapshots of bulk CB7CB phases comprised of 384 molecules and simulated using atomistic force field.

Invited 1

Investigation of materials with two nematic phases G. H. Mehl*1, C. Welch1, W. D. Stevenson2, X. B. Zeng2, H. X. Zou3, G. Ungar2,3

1Dept. of Chemistry and Biochemistry, University of Hull, Hull, HU6 7RX, UK

2Dept. of Materials Science and Engineering; University of Sheffield, Sheffield, UK 3Dept. of Physics, Zhejiang Sci-Tech University, Hangzhou, China

Thermotropic dimeric LC materials which exhibit two nematic phases have attracted considerable attention, as the low temperature phase has been found to be characterized by the spontaneous formation of chiral domains in non-chiral compounds and a heliconical packing of the molecules. In order to understand this phase behavior, arrays of materials have been synthesized and investigated. Here we will discuss the results based on sets of materials and mixtures designed with the specific aim of understanding the phase structure and structure-properties correlations for the formation of the low temperature nematic phase.

The focus of the discussion will be based on the design and synthesis of a number of dimeric and oligomeric systems centred on fluorinated terphenyl and as well as cyanobiphenyl units linked by flexible alkyl spacers. The chemistry has been controlled in such a way as to give symmetric and non-symmetric systems and this has been extended to oligomeric materials with spacers of both odd and even lengths and mixtures thereof. The synthesis and characterisation of these materials by OPM, DSC and detailed, temperature dependent XRD studies, as well as temperature dependent CD measurements will be presented and mixtures of these oligomers with the relevant dimers and other mesogens in the nematic and Ntb phases will be described and the results will be discussed in the context of models for the Ntb phase.

Acknowledgements Funding through the EPSRC grant EP/015726/1 is acknowledged. * Author for Correspondence: [email protected]

Invited 2

mailto:[email protected]

Photo-switchable bent-core liquid crystals

A. Eremin1*, R. Kurachkina 1, M. Alaasar 3, C. Tschierske 2, T. Börzsönyi 3, P. Salamon3 1Department of Nonlinear Phenomena, Institute for Physics, Otto von Guericke University

Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany 2Martin Luther University Halle-Wittenberg, Kurt Mothes Str. 2, D-06120 Halle (Saale),

Germany 3Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian

Academy of Sciences, H-1525 Budapest, P.O.B.49, Hungary

Development of multifunctional materials whose properties can be easily manipulated by fields and external stimuli are of paramount importance in modern technology. Photoswitchable soft materials are especially interesting for their possible applications in sensors and aligning systems. Bent-core liquid crystals distinguish by their tendency to form polar structures. Therefore designing photoswitchable bent-core mesogens opens new avenues to control polar and mechanical properties of liquid crystals optically. Another essential feature is the formation of long-living cybotactic and polar clusters of various symmetries. Their nature is still poorly understood. In our study, we investigate various photoswitchable 4-cyano resorcinol derivatives bent-core mesogens exhibiting cybotactic and polar clusters in the nematic phase. Depending on the direction of the COO group in the phenyl benzoate wing, core-fluorination, temperature, and the terminal alkyl chain length, cybotactic nematic and lamellar (smectic) LC phases were observed [1]. Fine-tuning of the molecular structure leads to photoresponsive bent-core (BC)LCs exhibiting a fast and reversible photoinduced change of the mode of the switching between ferroelectric- and antiferroelectric-like as well as a light-induced switching between an achiral and a spontaneous mirror-symmetry-broken LC phase. We observe the formation of the polar clusters already in the isotropic phase a few degrees above the nematic phase. One compound from this series is also distinguished by the sign inversion of the dielectric anisotropy.

Furthermore, we demonstrate an elastic anomaly, where the bend elastic constant is much smaller than the splay and twist constants over the whole N temperature range. We show reversible photomanipulation of the mechanical properties where the splay elastic constant decreases five-fold under the action of UV. This behaviour cannot be explained by steric considerations only, and presumably results from the clustering. In our presentation, we discuss the rheological and flexoelectric properties of this compound.

References [1] M. Alsaar, M. Prehm, S. Belau, N. Sebastián, M. Kurochkina, A. Eremin, Ch. Chen, F. Liu,

C. Tschierske Eur. J. Chem. A. 10.1002/chem.201806180, (2019) [2] M. Kurochkina, M. Alsaar, C. Tschierske, A. Eremin, in preparation (2019)


Invited 3

Fast response and low driving voltage DH-FLC mode of SmC* on the slippery interfaces

Jun Yamamoto1,2*, Koki Takamoto1,2 and Isa Nishiyama3,2

1 Department of Physics, Graduate School of Science, Kyoto University, Kyoto, 606, Japan 2JST-CREST, Saitama, Japan 3DIC, Saitama, Japan

Slippery interfaces are created by the disorder effect. We designed and realized several

models of self-organized slippery interfaces. For example, the localized impurities on the interface between liquid crystal and polymer thin films can weaken LC order near the interfaces. Then, the anchoring effect should be weakened, and molecular motion is greatly lubricated by the slippery interfaces. We have applied to the slippery interfaces to the homeotropic ferroelectric (SmC*) liquid crystals for the DH-FLC mode as walls wetted on the electrodes in the in-plane switching cel. Slippery interface provides us the following three big advantages for the efficiency of the light bulbs of flat panel application. (1) Driving voltage can be drastically reduced (~1.3 V/m). Mode efficiency have satisfied around 80% under 1.3V/m electric field. (2) Response time for the fast component does not decelerate and keeps the same speed as that of the original material (<100 sec) (Fig.1). (3) The speed of recovery to the black state can be accelerated by applying a short pulse with negative sign of the voltage (<100 sec almost same as rise-up time).

Furthermore, we characterize the slippery interface by measuring the dynamics of the surface director ns under rotational magnetic field. We analyze magnetic field dependence of the response of ns and evaluate the anchoring energy W and viscosity of surface director s. Poly-ethylene Glycol (PEG) surface shows “weak and lubricated” slippery interface. It should be noted that we can arbitrary control W by changing the stiffness of the network. Finally, we made a combination LCD cell which consist of the strong anchoring surface of polyimide for one of the inner surfaces of the glass substrates and used the slippery interface for the other. New LCD mode shows the good performances: (1) Mode efficiency greatly enhance near 100%, nevertheless strong anchoring modes only show 70~80%. This is because the large rotation of liquid crystal molecules on the surface near the IPS electrode. (2) Driving voltage can be reduced about 50%. This work was supported by JST-CREST (JPMJCR1424). *Author for Correspondence: *[email protected]

Figure 1. Driving voltage dependence of the response for the 3-state voltage of DH-FLC mode of SmC* on the slippery interface.

Figure 2. Temperature dependence of anchoring energy W and surface viscosity s on the slippery PEG-Gel films (s and W show in arbitrary units).

Invited 4

Structure analysis of electric-field-induced chiral smectic liquid crystalline phases by microbeam resonant X-ray scattering

Yoichi Takanishi1*, Atsuo Iida2, Atsuo Fukuda3, A.D.L.Chandani Perera4 and Jagdish K. Vij3

1 Graduate School of Science, Kyoto University, Kyoto, Japan

2 Photon Factory, High Energy Accelerator Research Organization, Ibaraki, Japan 3 Trinity College, The University of Dublin, Dublin, Ireland

4Department of Chemistry, University of Peradeniya, Peradeniya 20400, Sri Lanka

The successive phase transition between ferroelectric SmC* and antiferroelectric SmCA* is now one of the most interesting subjects. The molecular arrangement of the subphases (SmC* variants) is defined by the ratio of the synclinic ferroelectric ordering to the anticlinic antiferroelectric ordering in the unit structure, i.e., qT(=[F]/([F]+[A])), where [F] and [A] are number of synclinic ferroelectric and anticlinic antiferroelectric orderings, respectively, and at first two subphases with three- and four-layer periodicity has been experimentally determined by resonant X-ray scattering (RXS)[1]. In addition to subphases with three-, and four-layer periodicity, other subphases with a six-, seven-, eight- and ten-layer periodic structures have been experimentally observed by Feng et al. [2] and us [3].

Not only the temperature-induced but also an electric-field-induced successive phase transition in these chiral smectic LCs occurs. In this paper, we present two topics for the study of field-induced transitional phases in chiral LCs by microbeam RXS. 1) Electric-field-induced successive phase transition in subphases between SmC* and SmCA*

We studied SmCA* (qT=1/3) with three layer periodicity of several compounds. At a glance, field-induced transition subphases seem to be different; with the increase in applied electric field, C3p - C12p - “streak” - SmC* in Br-compound, C3p - C6p - “streak” - SmC* in Se-pure compound, and C3p - C9p - C6p - “streak”-SmC* transition in Se-mixture[4]. (Cnp means SmC* variant with n-layer periodicity). However, in all cases, the field-induced transition seems to occur on the basis of a three-layer block; the RRL block (“R” and “L” indicate the smectic layer with directors tilted to the right and left, respectively.) changes to an RRR block by simply flipping the director of one molecule, and the difference might be caused by the strength of long-range interaction.

2) Electric-field-induced phase transition in SmCα* SmCα* phase frequently appears between SmA and SmC*. It is optically uniaxial because of its nanometer-scale helical structure of incommensurate pitch. We studied the structure change of SmCα* under the electric field, and found the change depends on the helical pitch at zero-field; in short pitch range less than 3 layers (lower temperature range of SmCα*), the pitch elongates and attain to 3 layers with increasing the applied field, while in longer pitch range than 3 layers (higher temperature range of SmCα*), the pitch elongates and attain to 4 layers. From the electric-field-induced birefringence measurement, it is suggested that this 4 layer-unit field-induced transition phase is unexpectedly antiferroelectric-like, because the optical birefringence is negative.

[1] P. Mach et al., Phys. Rev. Lett. 81, 1015 (1998). [2] Z. Feng et al., Phys. Rev. E 96, 012701 (2017). [3] Y. Takanishi et al., Phys. Rev. E 87, 050503(R) (2013). [4] A. Iida et al., Phys. Rev. E 94, 052703 (2016). [5] A. Iida et al., Phys. Rev. E 97, 062702 (2018). * Author for Correspondence : [email protected]

Invited 5

Resonant Soft and Tender X-ray Scattering

of Liquid Crystal Phases: the past and future

Chenhui Zhu1* 1Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA

A key and fascinating feature of the NTB phase is achiral molecules forming a helicoidal structure. Conventional X-ray scattering techniques, that probe mostly electron density, do not provide information on helical pitch and relevant phase transitions. Recently, resonant soft X-ray scattering at carbon K-edge (RSoXS) has proven to be a unique and effective tool in directly probing periodic bond orientation variation in the NTB1, as well as in B4 helical nanofilaments2, blue phase3 and novels smectic phases4, 5. However, the use of soft X-rays also leads to practical complications, including (a) the requirement for vacuum sample environment and thin sample thickness due to its low penetration power and (b) the existence of many carbon atoms in a single organic molecule that may make it challenging to decipher molecular-level interactions. The above complications may be circumvented at some cost by operating at hard or tender X-ray energies (TReXS), such as 1-5 keV, which covers K-edges of many important elements (Na, P, S, Cl…). In this talk, I will discuss the origin of the resonant effect and its manifestations in the measured scattering in several liquid crystal structures6. Preliminary results on new applications of RSoXS and TReXS will be presented, and future opportunities at diffraction limited synchrotron sources will be discussed.

Acknowledgements: We acknowledge use of the Advanced Light Source supported by the Director of the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under contract no. DE-AC02-05CH11231.

References 1. C. Zhu, M. R. Tuchband, A. Young, M. Shuai, A. Scarbrough, D. M. Walba, J. E. Maclennan, C. Wang, A. Hexemer and N. A. Clark, Phys Rev Lett 116 (14), 147803 (2016). 2. C. Zhu, C. Wang, A. Young, F. Liu, I. Gunkel, D. Chen, D. Walba, J. Maclennan, N. Clark and A. Hexemer, Nano Lett 15 (5), 3420-3424 (2015). 3. M. Salamonczyk, N. Vaupotic, D. Pociecha, C. Wang, C. Zhu and E. Gorecka, Soft Matter 13 (38), 6694-6699 (2017). 4. J. P. Abberley, R. Killah, R. Walker, J. M. D. Storey, C. T. Imrie, M. Salamonczyk, C. Zhu, E. Gorecka and D. Pociecha, Nat Commun 9 (1), 228 (2018). 5. M. Salamonczyk, N. Vaupotic, D. Pociecha, R. Walker, J. M. D. Storey, C. T. Imrie, C. Wang, C. Zhu and E. Gorecka, Nat Commun 10 (1), 1922 (2019). 6. Y. Cao, J. Feng, Y. Arakawa, K. Q. Zhao, F. Liu, C. Zhu, to be submitted. * Author for Correspondence: [email protected]

Invited 6

Nematic Twist-Bend Phase in an external field Lech Longa

Marian Smoluchowski Institute of Physics, Department of Statistical Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków, Poland

*[email protected] The (one-dimensional modulated) nematic twist-bend phase (NTB), a fifth member of the

nematic family, formed through spontaneous chiral symmetry breaking in the isotropic and nematic phases of a large class of liquid crystalline systems of achiral molecules (bent-core-, dimeric-, trimeric, etc.) is one of the most spectacular recent discoveries in soft matter physics. It has become a major field of activity in liquid crystal research across the world [1]. Its unique property is a heliconical structure of nanoscale pitch , where the director rotates on the cone like in the smectic C*, but without long-range positional order of molecules. Initially, the theoretical concept of this phase has been presented by R. B. Meyer [2]. Subsequently Dozov [3] suggested that the formation of the NTB phase can be facilitated by the shape of bent–core molecules. In 2014 Shamid et. al. [4] showed that polar order induced by bend flexopolarization in liquid crystals of bent-core molecules can be responsible for the stabilization of NTB and of the novel class of blue phases. Their analysis was consistent with predictions of the mesoscopic theory of flexopolarization that we introduced as early as in 1990 [5, pp. 3464-3467]. Here, within generalized Landau-deGennes theory [5,6] we present theoretical studies concerning stability of NTB subjected to an external field relative to other homogeneous and inhomogeneous structures. We use a systematic bifurcation and numerical analyses to show that by controlling field’s strength and sign of anisotropy of permittivity a web of new one-dimensional modulated structures can be identified [7]. The model is further tested for CB7CB dimers where both the NTB phase and the uniaxial nematic phase appear stable. Acknowledgments

This work is supported by the Grant No. DEC-2013/11/B/ST3/04247 of the National Science Centre in Poland. [1] For a recent review see A. Jákli, O. D. Lavrentovich, and J. V. Selinger, “Physics of liquid crystals of

bent-shaped molecules”, Rev. Mod. Phys., 90, 045004 (2018). [2]R. B. Meyer, “Structural Problems in Liquid Crystal Physics”, pp. 273-373 in Les Houches Summer School in Theoretical Physics, 1973 (Gordon and Breach, New York, 1976); Phys. Rev. Lett. 22, 918 (1969). [3]I. Dozov, “On the spontaneous symmetry breaking in the mesophases of achiral banana-shaped molecules”, Europhys. Lett. 56, 247 (2001). [4] S. M. Shamid, S. Dhakal and J. V. Selinger, ‚“Statistical mechanics of bend flexoelectricity and the twist-

bend phase in bent-core liquid crystals”, Phys. Rev. E 87, 052503 (2013). [5] L. Longa and H.-R. Trebin, “Spontaneous polarization in chiral biaxial liquid crystals”, Phys. Rev. A 42,

3453 (1990). [6]Longa L, Pajak G., “Modulated nematic structures induced by chirality and steric polarization”. Phys Rev E. Rapid 93, 040701 (2016). [7] Pajak G., Longa L, Chrzanowska A., “Nematic twist--bend phase in an external field”, www.pnas.org/cgi/doi/10.1073/pnas.1721786115, PNAS, 115, E10303–E10312 (2018).

Invited 7

http://www.pnas.org/cgi/doi/10.1073/pnas.1721786115

Shifted photocurrent in a polar columnar liquid crystal F. Araoka1, C. Zhang1 and D. Miyajima1

1RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

Columnar liquid crystals (Col LC), particularly, those of p-stacked discotic molecular assemblies, have long time been enthusiastically studied as potential candidates of high-performance organic semiconductors. Many of these have high 1D carrier mobility, flexibility and nice wet processability due to the self-organization property [1]. On the other hand, recently, we have reported a polar Col LC which possesses a sustainable and electrically-switchable spontaneous polarization along the columnar axis, i.e. ferroelectricity [2]. This material is based on a super-molecular architecture of umbrella-like polar molecular assemblies piled up through hydrogen-bonding. Of course, it is very natural to expect the semiconducting behavior in our ferroelectric Col LC. However, unfortunately, it shows a disappointedly poor conduction property, maybe because of small p-orbital overlap due to the large molecular offset angle and/or carrier-trapping at the hydrogen-bonding.

In this work, a unique semiconducting behavior, like the so-called “shift-current” [3], was found in our new polar Col LC with a non-switchable polar core of subphthalocyanine. The sample was confined in a sandwich glass cell and polarly aligned by cooling from isotropic to the room temperature columnar phase under a DC electric field (5 V/µm). Interestingly, such a simple device exhibits distinctly biased photo-current signals with a short-circuit current (ISC) and an open-circuit voltage (VOC) even in the absence of external voltage application. ISC and VOC depend linearly on the cell thickness and shift in accordance with polarization reversal by the reversed pretreatment filed. The I-V curve shows an asymmetric shape with hysteresis, suggesting the push-pull effect on the bulk conduction carriers by the internal electric field due to the spontaneous polarization. Similar behaviors have been known in some inorganic ferroelectrics, but very rare in organic semiconductors. Although our material doesn’t show ferroelectricity, still it is polarly aligned with pretreatment and useful as a material for photo-sensors with a very simple device design based on a sandwich cell. We believe that the present result clearly suggests a new potential of ferroelectric LCs for electronics.

References [1] M. Funahashi, Polym. J. 41, 459 (2009). [2] Miyajima et al., Science 336, 209 (2012); Araoka et al., Adv. Mater. 25, 4140 (2013). [3] Nakamura et al. Nat. Commun. 8, 281 (2017). * Author for Correspondence: [email protected]

(a) (b)

Figure 1. (a) Schematics of our polar columnar liquid crystal. (b) Shifted photocurrent signals showing distinct ISC and VOC depending on the polarity.

Invited 8

Chirality propagation in liquid crystalline phospholipid membranes

A. Ferrarini1*, M. Pannuzzo2, D. Raciti3, A. Raudino3* and B. Szala1 1Department of Chemical Sciences, University of Padova, 35121 Padova Italy

2Italian Institute of Technology, 16163 Genova, Italy 2Department of Chemical Sciences, University of Catania, 95125 Catania, Italy

Biomembranes typically contain chiral guests, the most prominent example of which are intrinsic proteins. Such inclusions laterally interact with the lipid bilayer and this, as an elastic matrix, is expected to be able to propagate their chirality. Whereas the effect of chirality in tilted bilayer phases, such as the gel phase, has been investigated [1,2], the behaviour of the (untilted) liquid crystal phase remains to be explored. Some general insights were provided by recent studies of colloidal membranes, which offer the advantage of direct visualization [2]. However colloidal membranes, besides being two orders of magnitude thicker lipid bilayers, are made of particles that differ from phospholipids under several respects [3]. We have addressed the question of chirality propagation using Molecular Dynamics (MD) simulations and liquid crystal elastic continuum theory.

We performed coarse grained [4] MD simulations of a model helical particle embedded in a phospholipid bilayer. This behaves as a De Vries smectic [5] and the helical inclusion induces a radial tilt of the director, with a small, yet unambiguous twist on opposite sense for a right-and a left-handed inclusion. On the contrary, a tangential tilt would be observed for a colloidal membrane, which has a conventional smectic behaviour.

Elastic continuum theory allows us to relate the perturbation induced by the inclusion to the elastic properties of the bilayer. The decay length, on the nanometer scale, is controlled by the competition between the energetic cost for splay (bending in the language of lipid bilayers) and tilt deformations, whereas the magnitude of the chiral perturbation is determined by the strength of the interaction at the lipid/inclusion interface. The behaviour is analogous to that of colloidal membranes, where however the splay must be replaced by a twist deformation [6].

References [1] R. C. Sarasij, P. Srivastava, and M. Rao, Phys. Rev. E 85, 041920 (2012); J. V. Selinger, M. S. Spector, and J. M. Schnurr, J. Phys. Chem. B 105, 7157–7169 (2001). [2] E. Barry, and Z. Dogic, Proc. Natl. Acad. Sci. USA 107, 10348–10353 (2010); P. Sharma et al, Nature 513, 77–80 (2014); L. Kang, and T. C. Lubensky, Proc. Natl. Acad. Sci. USA 114, E19–E27 (2017); T. Gibaud et al, Proc. Natl. Acad. Sci. USA 114, E3376-E3384 (2017). [3] W. Stillwell, An introduction to Biological Membranes, 2nd Ed., Elsevier, (Amsterdam, 2016). [4] S. J. Marrink et al, J. Phys. Chem. B 111, 7812-7824 (2007); D. H. de Jong et al, J. Chem. Th. Comp. 9, 687–697 (2013). [5] A. De Vries, Molec. Cryst. Liq. Cryst. 41, 27–31 (1977). [6] E. Barry et al, J. Phys. Chem. B 113, 3910-3913 (2009). * Authors for Correspondence: [email protected], [email protected]

Invited 9

Nanoplate Liquid Crystals in External Fields

Zhengdong Cheng*1, Abhijeet Shinde1, Dali Huang1,

Ugochukwu Okeibunor1 and Mingfeng Chen2 1Artie McFerrin Department of Chemical Engineering, Texas A&M University,

College Station, Texas 77843-3122, USA 2 Soft Matter Center, Guangdong Province Key Laboratory of Functional Soft

Condensed Matter, School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China

Colloidal anisotropic platelets are model systems for discotic liquid crystal investigation. We have systematically studied the ZrP monolayers, as well as Graphene Oxides and other 2D colloids, due to the capability to control the size and surface chemistry [1]. Orientation of colloids in liquid crystalline states can be controlled by external electric, magnetic fields [2]. The change of defect structure in nematic under external electric field showed evidence for uniaxial nematic to biaxial nematic phase transition. Thermophoretic studies on zirconium phosphates showed that an originally isotropic suspension of nanoplates underwent isotropic-nematic phase transition in a long (~30mm) capillary kept in a linear temperature gradient. Due to thermophilic nature of the ZrP nanoplates, the platelet concentration at the hot end increased above I-N transition point and nematic phase was nucleated.

Acknowledgements The authors wish to acknowledge financial support from NASA (NASA-NNX13AQ60G).

References [1] D. Sun et al., “Stable smectic phase in suspensions of polydisperse colloidal platelets with identical thickness” Phys. Rev. E. 80, 041704 (2009). [2] M. Chen, A. Shinde et al., “Rainbows in a vial: controlled assembly of 2D colloids in two perpendicular external fields” 2D Mater. 6, 025031 (2019). * Author for Correspondence: [email protected]

Figure 1. Michel-Levy interference color bands in nematic phase with long-duration sedimentation of nanoplates and application of magnetic field. 𝜙𝑖𝑛𝑖𝑡𝑖𝑎𝑙 = 0.0280 ± 0.0003 and 0.6M TBACl, crossed polarizers arranged 45° from the vertical; magnetic field strength 2 tesla. Width of sample container was 10 mm [2].

Invited 10

Cubic and other 3D phases from interlocking twisted ribbons

X.B. Zeng,1 H.J. Lu,1 Y.X. Li,1 G. Ungar,2* J. Wang,2 Y. Wang,2 C. Dressel,3 C. Tschierske,3 F. Liu,2 H.F. Cheng,4 X.H. Cheng4

1 Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, U.K.

2 State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, Xian 710049, China

3 Department of Chemistry, Martin Luther University Halle-Wittenberg, 06120 Halle, Germany 4 Key Laboratory of Medicinal Chemistry from Natural Resources, Chemistry Department,

Yunnan University, Kunming, China Bicontinuous cubic phases in thermotropic LCs have been found so far in compounds of 3 different architectures: wedge-shaped or disk-shaped with tethered chains, rod-like with one or more terminal chains (polycatenars, PC), and rod-like with laterally attached chains. Bicontinuous phases in the second group, PC, are particularly interesting since it had recently emerged that their infinite networks consist of helically twisted ribbons with the helical sense matched at the junctions, thereby propagating homochirality to infinity even in non-chiral compounds [1]. The requirement for twist and space-filling of interlocked ribbons is the reason that PCs display several 3D bicontinuous phases not seen in other soft-matter systems. This includes the Triple Network cubic [2], and the “Smectic-Q” tetragonal phases [3]. The realization that the Triple Network is always chiral prompted us to re-examine its structure, and the new lower-symmetry model will be presented [4]. It will also be shown that the concept of interlocking twisted ribbon is not limited to network phases, and that it can also account for some other newly found 3D LC structures.

References: [1] C. Dressel, F. Liu, M. Prehm, X.B. Zeng, G. Ungar, and C. Tschierske Angew. Chem. Int. Ed. 53, 13115 –13120 (2014). [2] X.B. Zeng, G. Ungar, and M. Impéror-Clerc, Nature Materials, 4, 562-567 (2005). [3] H. J. Lu, X. B. Zeng, G. Ungar, C. Dressel, and C. Tschierske Angew. Chem. Int. Ed. 57, 2835-2840 (2018). [4] X.B. Zeng, and G. Ungar, submitted. * Author for Correspondence: [email protected]

Invited 11

Oligomeric odd-even effect in liquid crystals

Rony Saha1, Greta Babakhanova2, 3, Zeinab Parsouzi1, Mojtaba Rajabi1, Prabesh Gyawali1, Chris Welch4, Georg H. Mehl4, James Gleeson1, Oleg D. Lavrentovich1,2, 3, Samuel Sprunt1,*

and Antal Jákli1, 2, 3, * 1Physics Department, Kent State University, Kent, OH 44242, USA

2Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA 3Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA

4Department of Chemistry, University of Hull, Hull, UK

Odd-even effects, oscillations in properties of materials comprised of an odd or even number of connected repeating units, are well-known phenomena in materials science. In organic materials, they are usually associated with the number of methyl groups in aliphatic chains. In this work, we unveil multiple signatures of a new odd-even effect in liquid crystals that occurs at the larger scale of molecular moieties that by themselves express liquid crystalline behavior. We demonstrate that oligomeric liquid crystals, with n=1-4 number of rigid mesogenic segments connected by flexible aliphatic chains with an odd number of methyl groups, produce an odd-even effect in optical anisotropy and the bend elastic constant of the liquid crystal oligomer. This effect is different from the usual odd-even effects with respect to the parity of carbon atoms in an aliphatic chain and can be understood in term of the average molecular shape and the associations between n-mers based on the packing of these shapes. We also show that, in spite of the fact that there is no long-range electron density modulation, careful analysis of synchrotron SAXS results can provide important information about the molecular associations in the N and NTB phases that other techniques cannot access. This novel odd-even effect opens up a new mode to optimize phase and optical behavior.

Acknowledgements This work was supported by the US National Science Foundation under grants DMR-1410378 and DMR-1307674 and the (UK) EPSRC project EP/M015726/1. This research used the CMS beamline 11-BM of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. We are particularly grateful to M. Fukuto and R. Li for their advice and assistance in performing the measurements at NSLS II.

* Author for Correspondence: [email protected] and [email protected]

Invited 12

Oral Abstracts

Novel Elastic Response in Twist-bend Nematic Models

Jiale Shi1, Hythem Sidky1, Jonathan K. Whitmer*1 1Department of Chemical and Biomolecular Engineering, University of Notre Dame,

Notre Dame, IN, USA

Bent-shaped liquid crystals have attracted significant attention recently due to their novel mesostructure and the intriguing behavior of their elastic constants, which are strongly anisotropic and have an unusual temperature dependence. Though theories explain the onset of the twist-bend phase through spontaneous symmetry breaking concomitant with transition to a negative bend (K3) elastic constant, this has not been observed as yet in experiments. There, the small bend elastic constant has a strongly non-monotonic temperature dependence, which first increases after crossing the isotropic (I)–nematic (N) transition, then dips near the nematic (N)–twist-bend (NTB) transition before it increases again as the transition is crossed. The molecular mechanisms responsible for this exotic behavior are unclear. Here, we utilize Density of States algorithms in Monte Carlo simulation applied to a variant of the Lebwohl–Lasher model which includes bent-shaped-like interactions to analyze the mechanism behind elastic response in this novel mesostructure and understand the temperature dependence of its Frank–Oseen elastic constants.


Oral 1

A New Twist on the Electroclinic Critical Point: Type I and Type II Smectic C* Systems

J. Ziegler1,2, S. Echols1, M. Moelter1 and K. Saunders1,* 1Department of Physics, Cal Poly, San Luis Obispo, CA 93042 USA

2Department of Physics, University of Oregon, Eugene, OR 97403, USA We analyze the electroclinic effect in chiral, ferroelectric liquid crystal systems that have a first order Sm-A*—Sm-C* transition, and show that such systems can be either Type I or Type II. In temperature—field parameter space Type I systems exhibit a macroscopically achiral low-tilt—high-tilt critical point, discovered by Bahr and Heppke [1]. By macroscopically achiral we mean that the Sm-C* helical superstructure is expelled, and we denote this phase Sm-C. This critical point terminates a first order phase boundary of low-tilt Sm-C—high-tilt Sm-C transitions, and extends to an achiral-chiral triple point. At this triple point the low and high tilt Sm-C phases coexist along with a Sm-C* phase that exhibits a modulated superstructure. In Type II systems the critical point, triple point, and first order boundary are replaced by a Sm-C* region, sandwiched between low and high tilt Sm-C phases. Correspondingly, as the field is ramped up, the Type II system will display a reentrant Sm-C—Sm-C*—Sm-C phase sequence. Moreover, the discontinuity in the tilt of the optical axis at each of the two phase transitions means the Type II system is tristable, in contrast to the bistable nature of the low tilt Sm-C—high tilt Sm-C transition in Type I systems. Whether the system is Type I or Type II is determined by the ratio of two length scales, one of which is the zero-field Sm-C* helical pitch. The other length scale depends on the size of the discontinuity (and thus the latent heat) at the zero-field first order Sm-A*—Sm-C* transition. We make a complete mapping of the phase boundaries in all regions of temperature–field–enantiomeric excess parameter space (not just near the critical point) and show that a variety of interesting features are possible, including a multicritical point, tricritical points and a doubly reentrant Sm-C—Sm-C*—Sm-C —Sm-C*phase sequence.

Acknowledgements Financial support was provided by the National Science Foundation.

References [1] Ch. Bahr and G. Heppke, Mol. Cryst. Liq. Cryst. 313, 150, (1987); Phys. Rev. A 39, 5459 (1989).


Oral 2

Molecular Correlations, Fluctuations, and Order in the Twist-Bend Phase

Michael R. Tuchband,1 Min Shuai,1 Joseph Yelk,1 Dong Chen,1 Chenhui Zhu,2 Leo

Radzihovsky,1 Arthur Klittnick,1 Lee Foley,3 Alyssa Scarbrough,3 Jan H. Porada,3 Mark Moran,3 Keri A. Graber,1 Justin B. Hooper4, Dmitry Bedrov4, Eva Korblova,3 David M. Walba,3

Alexander Hexemer,2 Joseph E. Maclennan,1 Matthew A. Glaser,1 and Noel A. Clark1*

1Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309-0390, USA

2Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

3Department of Chemistry and Biochemistry and Soft Materials Research Center, University of Colorado, Boulder, CO 80309-0215, USA

4Department of Materials Science and Engineering, The University of Utah, Salt Lake City, UT, USA and Soft Materials Research Center, University of Colorado, Boulder, CO 80309-0390

We will describe the structure of local molecular positional pair correlations in the twist-bend phase, showing that they are chain-like, stabilized by dynamic three-body clusters comprising a molecular upper end, a molecular lower end, and a molecular middle, the center of the flexible linker of a third molecule. This theme of nanosegregation generates self-assembled, chain-like correlations of interlocking bent dimers, in the form of local brickwork tilings [1] of ~5 molecules, into duplex, double-helical oligomeric arrangements.

We will then present the results of resonant soft x-ray scattering in the nematic phase, showing several examples of how these correlations develop upon cooling from the nematic.

Acknowledgments

Work supported by US NSF Grants DMR 1710711 and MRSEC 1420736. References

[1] “Double-Helical Tiled Chain Structure of the Twist-Bend Liquid Crystal phase in CB7CB” http://arxiv.org/abs/1703.10787


Oral 3

Paramagnetic antiferroelectrics: bent-core mesogens derived from the Blatter radical

Piotr Kaszyński,1,2,3 Shivakumar I. Kilingaru,1 Damian Pociecha,4 Jacek Szczytko,5 and Hirosato Monobe6

1 Centre of Molecular and Macromolecular Studies, PAS, 90-363 Łódź, Poland

2 Faculty of Chemistry, University of Łódź, 91-403, Łódź, Poland 3 Department of Chemistry, MTSU, Murfreesboro, TN 37132, USA

4 Department of Chemistry, University of Warsaw, 02-089 Warsaw, Poland 5 Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland

6 National Institute of Advanced Industrial Science and Technology (AIST), Kansai Centre, Ikeda, Osaka 563-8577, Japan

A combination of paramagnetic properties of organic radicals with the fluid nature of the

liquid crystalline phase is potentially useful for technological applications in molecular electronics and spintronics. Therefore, we focused on the benzo[e][1,2,4]triazinyl, an exceptionally stable π-delocalized radical (Blatter radical, I), which upon appropriate substitution (II) forms lamellar and columnar phases exhibiting structure-dependent magnetic behavior [1].

To improve the phase organization and intermolecular spin-spin communication we introduced the “planarized” Blatter radical fragment [2] and investigated a series of bent-core mesogens of type III. Higher anisometry of the central paramagnetic fragment resulted in the formation of an antiferroelectric B2 phase with a tristable electro-optical switching. Synthesis, magnetic properties, structural (XRD) and electrooptical results will be presented.

Acknowledgements

Support was provided by NCN (2014/13/B/ST5/04525) and FNP (TEAM-3/2016-3/24) grants.

References [1] Jasiński, M.; Szczytko, J.; Pociecha, D.; Monobe, H.; Kaszyński, P. J. Am. Chem. Soc. 2016, 138, 9421; Kapuściński S., Gardias A., Pociecha D., Jasiński M., Szczytko J., Kaszyński P, J. Mater. Chem. C, 2018, 6, 3079. [2] Kaszyński, P.; Constantinides, C. P.; Young, V. G. Jr. Angew. Chem. Int. Ed. 2016, 55, 11149. * Author for Correspondence: [email protected]

N

NN

N

NN

Y

X

Z

N

NN

Y

X

Z

O

I II III

X, Y, Z = mesogenicity-inducing substituent or H

Oral 4

Figure 1. Textures observed in a 3 m cell with planar alignment by PLOM and XRD patterns for 1c in a) the SmXPF phase at 150 °C; b) Crystal (B3) phase at 25 °C and c) for 2a at 25 °C (DC).

Isoxazolines as novel building blocks for Polar Smectic Phases

R. R. da Rosa*1, R. Visvanathan2, C. S. B. Weber1, E. Guzman3, A. Scarbrough3, A. Duncan2, E. D. Korblova3, R. Shao2, N. A. Clark2, D. M. Walba3, A. A. Merlo1

1Chemistry Institute, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil 2Department of Physics, University of Colorado Boulder, CO, USA

3Department of Chemistry and Biochemistry, University of Colorado Boulder, CO, USA

Chirality and polarity from bent-core liquid crystals (BCLC) are valuable features from a phenomenological and technological viewpoint. Ferroelectricity and frustrated LC phases are related both with molecular or superstructural chirality.[1] In this work we report the synthesis and characterization of the first example of racemic symmetric isoxazolines-based BCLC showing ferroelectric behavior and a possible dark conglomerate (DC) phase. The synthetic strategy follows the main step of isoxazoline preparation method as described previously [2], then the amine derivative is used in an condensation reaction with the isophthalic aldehyde, giving the Schiff's bases (SBs) 1a-d and 2a-b in good yields (~55%). Isoxazolines 1b-d showed a SmXPF phase with Ps~500 nC/cm² while 2a-b, with inverted heterocycle in the structure, presented a possible DC phase. The polar phase could not be assigned as SmAPF or SmCaPF since they display the same texture by POM. The DC phase structure should be also confirmed by freeze-fracture TEM. Saddle splay deformation and sponge-like morphology could be analyzed considering that it does not show conglomerates with the polarizer rotation. In previous work we have shown that the isoxazoles dipole moment direction has a direct influence on the phase type of BCLC simply by changing the heterocyclic moiety direction.[3] The isoxazolines based banana-shaped molecules demonstrate again that a change in orientation of the molecular dipoles, with minute change in the structure, gave different bent-core phases. They have also proven to be a powerful new building block for the polar smectic phases that can be further investigated and applied in electronic devices in the future.

Acknowledgements The authors wish to thank CAPES, CNPq (Ed Universal) and NSF for the financial support.

References [1] H. Ocak, B. Bilgin-Eran, M. Prehm and C. Tschierske, Soft Matter, 8, 7729–7990 (2012). [2] G. D. Vilela, R. R. da Rosa, et al. Tetrahedron Lett., 52, 6569–6572 (2011). [3] R. R. da Rosa et al., Poster session presented at: 27

th International Liquid Crystal

Conference, Kyoto, Japan, 22nd-27th July (2018). * Author for Correspondence: [email protected]

a)

b)

c)

Oral 5

Criticality of pitch for the observation of partially unwound

helical mode in ferroelectric liquid crystals

S. Khan1, J. Prakash*1, S. Chauhan1 A. Choudhary2 and A. M. Biradar3

1Department of Physics, Aligarh Muslim University, Aligarh, UP-202002, India;

2Physics Department, Deshbandhu College (University of Delhi), Kalkaji, New Delhi-110019, India;

3CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi-110012, India.

Gaining importance from fast switching speed, high optical contrast, optical memory effect etc., ferroelectric liquid crystal (FLC) materials have proved them to be a better candidate in fundamental and applied research. To exploit the material properties in full, we need to understand the complexity involved in the helical relaxation process and the molecular functionality of FLC materials. The dielectric spectroscopy is employed to observe the behavior of dielectric relaxation processes in this regard. Here, we present a low frequency dielectric relaxation process, known as partially unwound helical mode (p-UHM), along with the well established Goldstone mode (GM) process in a FLC material, namely SCE-13 in Sm C* phase [1-3]. It was found that p-UHM was dominantly observed in the surface-stabilized FLC (SSFLC) geometry, where the thickness of the sample cell is less than the pitch of the material. The fluctuations of unwound helical structure in the SSFLC was compared with volume-stabilized FLC geometry (VSFLC), where the thickness of the sample cell is more than the pitch of the material) through dielectric relaxation spectroscopy. The occurrence of the low frequency mode was attributed to the unwound helical structure and net contribution of spontaneous polarization in the SSFLC state. The change in dielectric parameters has been extensively studied. The behavior of the relaxation frequency of the low frequency mode with applied DC bias has also been demonstrated. The textural observations have shown three different domains in the SSFLC state indicating that some of the molecules apart from the up and down position are off the axis. These studies give fundamental insights into the effect of p-UHM in the SSFLC state which in turn will be helpful in fabricating better LC devices for futuristic electro-optical applications.

Acknowledgements The authors wish to thank the Council of Scientific and Industrial Research, New Delhi, India for providing financial assistance under the EMR project No.-3 (1395)/17/EMR-II.

References [1] A. Choudhary, A. Bawa, Rajesh, S. P. Singh and A. M. Biradar, Phys. Rev E. 95, 062702 (2017). [2] L. K. Gangwar, A. Bawa, A. Choudhary, S. P. Singh, Rajesh and A. M. Biradar, Phys.

Rev E. 97, 062707 (2018). [3] A. Bawa, L. K. Gangwar, A. Dhingra, A. Choudhary, Rajesh, S. P. Singh, W. Haase and A. M. Biradar, Liq. Cryst. 46, 166-175 (2018). *Author for Correspondence: [email protected]

Oral 6


Stimuli-Responsive Mesostructured Hybrid Materials

Y. Yuan1, H. Mundoor1, B. Senyuk1, Q. Liu1 and I. I. Smalyukh1,2,3,4* 1Department of Physics, University of Colorado Boulder, Boulder, CO, USA

2Department of Electrical, Computer, and Energy Engineering, Materials Science and Engineering Program, Boulder, CO, USA

3Soft Materials Research Center, University of Colorado, Boulder, CO, USA 4Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory

and University of Colorado, Boulder, CO, USA Composite materials with tunable physical behavior are designed through integrating unique properties of solid nanostructures with the facile responses of soft matters to weak external stimuli. Here we report the fabrication of such materials via the self-assembly of nanoparticles mediated by the elasticity of liquid crystals.

Optically biaxial molecular-colloidal fluids [1]. Micrometer-long inorganic photon-upconverting colloidal rods are dispersed in a fluid host of nanometer-long organic molecular rods. A coarse-grained model explains the experimental temperature-concentration phase diagram with two uniaxial and one biaxial nematic phases, as well as the orientational distributions of rods. Displaying properties of biaxial optical crystals, these hybrid molecular-colloidal fluids can be switched by electric and magnetic fields and exhibit facile responses to other external stimuli.

Optically reconfigurable elastic colloidal monopoles [2]. Differently from electrostatics, like-charged elastic monopoles attract and oppositely charged ones repel. The sign and magnitude of elastic charges we developed can be switched by ambient-intensity unstructured light and the monopoles can even be transformed to quadrupoles at will. We also demonstrate the out-of-equilibrium dynamic assembly of these colloidal particles. Our findings may lead to light-powered active-matter systems and self-assembled nanomachines.

Chiral nematic colloidal self-assembly [3]. The effects of distortions caused by chiral springs and helices on the colloidal self-organization in a nematic liquid crystal are probed using laser tweezers, particle tracking and optical imaging. We show that chirality of colloidal particles interacts with the nematic elasticity to predefine chiral or racemic colloidal superstructures in nematic colloids. These findings are consistent with numerical modelling based on the minimization of Landau–de Gennes free energy. Our study uncovers the role of chirality in defining the mesoscopic order of liquid crystal colloids, suggesting that this feature may be a potential tool to modulate the global orientated self-organization of these systems.

References [1] H. Mundoor, S. Park, B. Senyuk, H. Wensink and I. I. Smalyukh. Hybrid molecular-colloidal liquid crystals. Science 360, 768-771 (2018). [2] Y. Yuan, Q. Liu, B. Senyuk and I. I. Smalyukh. Elastic colloidal monopoles and out of equilibrium interactions in liquid crystals. Nature 570, 214-218 (2019). [3] Y. Yuan, A. Martinez, B. Senyuk, M. Tasinkevych, and I. I. Smalyukh. Effects of chirality on elastic interactions and colloidal self-assembly in nematic liquid crystals.” Nature Mater. 17, 71–78 (2018). * Author for Correspondence: [email protected]

Oral 7

Activated chirality of bent-core achiral smectics

A. A. S. Green1, M. R. Tuchband1, R. Shao1, Y. Shen1, R. Visvanathan1, A. E. Duncan1, A. Lehmann3, C Tschierske3, E. D. Carlson2, E Guzman2, M. Kolber2, D. M. Walba2,

C. S. Park1, M. A. Glaser1, J. E. Maclennan1, and N. A. Clark*1 1Department of Physics, 2Department of Chemistry, Soft Materials Research Center,

University of Colorado Boulder, Boulder, CO, USA 3Department of Chemistry, Martin Luther University Halle-Wittenberg, Halle, Germany

We report the discovery and characterization of two novel smectic phases exhibited by an achiral, bent-core mesogen: a high-temperature, de Vries phase and an incommensurate helical phase. Motivated originally by a strong interest in finding a uniaxial, fast, switchable material, PAL30 was originally reported to have orthogonal phases [1]. We show, using optical microscopy and resonant X-ray scattering, that the smectic phases of PAL30 are in fact tilted. The first smectic phase observed on cooling from isotropic, Sm1, is a de Vries-like phase that appears uniaxial in planar cells. In contrast to the strong coupling between tilt and polarity characteristic of most bent-core phases, these characteristics are completely decoupled in the high temperature range of the Sm1. On application of an electric field above a threshold, Eth, however, the Sm1 develops spontaneous, field-activated chirality, switching into a chiral SmCSPF phase. The next phase, Sm2, is an incommensurate helical phase. In keeping with the naming conventions established for helical calamitic phases, the Sm2 was dubbed the Sm(CP)α, though it has recently also been called the SmCSSF

hel phase by the Dublin group [2]. The helical nature of the Sm2 is confirmed by Umklapp analysis of the X-ray scattering, where the missing (l=1, m=-1) harmonic peak indicates that there are significant helical fluctuations. These helical fluctuations suggest some similarity with the nematic twist-bend phase, and indeed, a very similar twist-bend smectic phase has recently been identified by Abberley et al. [3]. The emergence of spontaneous chirality in soft matter is of perennial interest to the scientific community, and we are excited to report a bent-core smectic where the chirality may be induced by an applied electric field.

**This work was supported by the Soft Materials Research Center under NSF MRSEC Grant DMR-1420736 and NSF MRSEC Grant DMR-1710711, by NASA Grant NNX-13AQ81G, and by DFG Grant Ts 39/24-2. RSoXS measurements were made at the Advanced Light Source, which is a DOE Office of Science User Facility operated under Contract No. DE-AC02-05CH11231. We acknowledge the assistance of beamline scientist Cheng Wang. SAXS measurements were carried out at the National Synchrotron Light Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-AC02-98CH10886.

[1] Panarin, Y. P., Nagaraj, M., Sreenilayam, S., Vij, J. K., Lehmann, A., and Tschierske, C. Phys. Rev. Lett., 107(24), 247801 (2011) [2] Vij, J. K., Panarin, Y. P., Sreenilayam, S. P., Alaasar, M., & Tschierske, C. Phys. Rev. Mater., 3(4), 045603. (2019). [3] Abberley, J. P., et al. Nat. Comm., 9(1), 228 (2018); J. P. Abberley, R. Killah, R. Walker, J. M. D. Storey, C. T. Imrie, M. Salamonczyk, C. Zhu, E. Gorecka, and D. Pociecha, Nat. Commun. 9, 2856 (2018).


Oral 8

Fine-tuning of the highly sensitive chirality amplification through space of chiral ligand-capped nanomaterials

visualized in the induced cholesteric phase

A. Nemati1, S. Shadpour1, L. Querciagrossa2, J. P. Vanegas1, L. Bergquist1, T. Mori1,3, A. Sharma1, C. Zannoni2, and T. Hegmann1,4*

1Advanced Materials and Liquid Crystal Institute, Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, United States

2Dipartimento di Chimica Industriale “Toso Montanari” and INSTM, Università di Bologna, Viale Risorgimento 4, IT-40136 Bologna, Italy

3Graduate School of Frontier Science, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa 277- 0827, Japan

4Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States

The focus of our work is to establish design rules for the amplification of chirality through space by chiral ligand-modified nanomaterials. We established that the use of induced cholesteric LC phases, as a non-spectroscopic approach, in combination with calculations of a suitable pseudoscalar chirality index permit visualization and ranking of the extent of chirality transfer and amplification from chiral molecule-capped nanomaterials to a surrounding LC medium. These studies examine size, shape and nature as well as density and type of the nanomaterial ligand shell, and as it turns out, N-LC phases are an ideal platform to examine these effects.

Our data revealed that more effective chirality transfer to a bulk N-LC phase is possible1 when a chiral molecule monolayer-protected surface is broken up into small nanoparticle ‘pieces’. Most noteworthy, the presence of chiral ligand-capped gold nanoparticles results in helical distortions of a much larger number of N-LC host molecules surrounding each nanoparticle in comparison to their organic chiral counterparts.2 Hence, the chiral correlation length for the same chiral structure or molecule is significantly larger when it is confined at a certain density to a curved nanoscale interface and drastically larger when this curved nanoscale surface is desymmetrized as, for example, in gold nanorods3,4 with higher chiral anisotropy factors.

Acknowledgements The authors wish to thank NSF (DMR-1506018, CHE-1659571), the Italian MIUR (PRIN project 2015XJA9NT), and the Ohio Third Frontier Program for financial support.

References [1] A. Sharma, T. Mori, H.C. Lee, M. Worden, E. Bidwell, T. Hegmann, ACS Nano 8, 11966-11976 (2014); L. Bergquist, T. Hegmann, ChemNanoMat 3, 863-868 (2017); S. Shadpour, J. P. Vanegas, A. Nemati, T. Hegmann, ACS Omega 4, 1662-1668 (2019). [2] T. Mori, A. Sharma, T. Hegmann, ACS Nano 10, 1552-1564 (2016). [3] A. Nemati, S. Shadpour, L. Querciagrossa, L. Li, T. Mori, M. Gao, C. Zannoni, T. Hegmann, Nat. Commun. 9, 3908 (2018). [4] A. Nemati, S. Shadpour, L. Querciagrossa, T. Mori, C. Zannoni, T. Hegmann, ACS Nano, in press (2019). * Author for Correspondence: [email protected]

Oral 9

Exploiting directed self-assembly to enable functional performance in liquid crystalline elastomers

T. White*1, B. Donovan1, J. McCracken1, K. Schlafmann1, and H. Fowler1 1Department of Chemical and Biological Engineering, University of Colorado Boulder,

Boulder, CO 80309, USA

Liquid crystalline materials are pervasive, enabling devices in our homes, purses, and pockets. It has been long-known that liquid crystallinity in polymers enables exceptional characteristics in high performance applications such as transparent armor or bulletproof vests. This talk will generally focus on a specific class of liquid crystalline polymeric materials: liquid crystalline elastomers. These materials were predicted by de Gennes to have exceptional promise as artificial muscles, owing to the unique assimilation of anisotropy and elasticity. Subsequent experimental studies have confirmed the salient features of these materials, with respect to other forms of stimuli-responsive soft matter, are large stroke actuation up to 400% as well “soft elasticity” (stretch at minimal stress).

This presentation will survey our efforts in directing the self-assembly of these materials to realize distinctive functional behavior with implications to soft robotics, flexible electronics, and biology. Most notably, enabled by the chemistries and processing methods developed in my laboratories, we have prepared liquid crystal elastomers with distinctive actuation and mechanical properties realizing nearly 20 J/kg work capacities in homogenous material compositions. Local control of orientation dictates nonuniformity in the elastic properties, which we recently have shown could be a powerful means of ruggedizing flexible electronic devices. Facile preparation of optical films, prepared with the cholesteric phase, capable of concurrent shape and color change will also be discussed.


Figure 1. Prior research dictating topology into liquid crystalline networks and elastomers (LCEs). (a) A 3x3 array of +1 topological defects is imprinted into an LCE and transforms from flat to 3-d upon heating. (b) The stretch-based deformation of layered LCE actuators can accomplish significant work, here lifting 56 g, more than 2000x the weight of the material. (c) The shape deformation can be sensitized to electric fields, by including carbon nanotubes. (d) Synthesis and incorporation of a novel photochromic monomer enables all-optical reconfiguration of shape. (e) Concurrent shape and color change in reflective films prepared from cholesteric liquid crystal elastomers.

Oral 10

Chirality imprinting from chiral superstructures formed by

achiral molecules to achiral mesogens

Jae-Jin Lee, and Suk-Won Choi*

Department of Advance Materials Engineering for Information and Electronics (BK21Plus),

Kyung Hee University, Youngin-shi, Gyeonggi-do, 17104, Korea Recently, several attempts have been made to construct chiroptical soft materials using mixed systems of achiral bent-core and rod-like mesogenic molecules. Various physical measurements have suggested the occurrence of nanoscale phase segregation in these mixed systems. In these systems, a large circular dichroism (CD) was observed, and it is known that this CD signal is originated from the chiral superstructures in segregated nanospaces embedded between the HNFs or around the HNFs. Herein, we try to stabilize the chiral superstructure in segregated nanospaces by reactive mesogens. First, we prepared a mixture of HNFs (bent-core molecules) and a reactive mesogen-possessing nematic phase. The reactive mesogen in the nano-spaces was fixed via UV irradiation. Then, HNFs were dissolved in a solvent. The remaining networks of the reactive mesogens were observed via microscopic measurements. After then, we replaced HNFs with another low-molecular nematic mesogen. Interesting, a large CD signal originated from the low-molecular nematic mesogen was observed. Thus, it was found that the chirality of the polymer-stabilized superstructres can be imprinted into the low-molecular nematic mesogen. Details will be reported in the FLC 2019.

Oral 11

Q-tensor model of twist-bend and splay nematic phases

Martin Čopič and Alenka Mertelj

Insitute J. Stephan Jamova 37, 1000 Ljubljana, Slovenia

The twist-bend nematic phase is characterized by a conically twisting director and by a dramatic softening of the bend elastic constant. The instability towards bend can theoretically also induce a splay-bend phase with a bend-splay modulation along the director. Recently we found another modulated nematic phase where the splay elastic constant tends to zero, resulting in a splay modulation perpendicular to the director [1]. These phases can be modeled by a single Q-tensor free energy with a term that breaks the degeneracy between the splay and bend elastic constant and with a flexoelectric coupling of the divergence of the Q-tensor with polarization.

Acknowledgements

This work was funded by the Slovenian Research Agency research core funding No. P1-0192 and project No. J7-8267. MČ would also like to thank the Isaac Newton Institute for Mathematical Sciences for support and hospitality during the programme The mathematical design of new materials when work on this paper was undertaken.


Oral 12

The Effect of an Ethynyl Spacer on Mesomorphic and ‘de Vries-Like’ Properties of Tricarbosilane Mesogens

Zia Ahmed,1 Carsten Müller,2 Andreas Bogner,2 Frank Giesselmann2, Robert P. Lemieux *1 1Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada

2Institute of Physical Chemistry, University of Stuttgart, Stuttgart, Germany The tricarbosilane-terminated mesogen QL16-6 undergoes a transition from the orthogonal SmA phase to the tilted SmC phase with a maximum layer contraction of only 0.5% [1]. Such 'de Vries-like' liquid crystals present a solution to the intractable problem of chevron formation in surface-stabilized ferroelectric liquid crystal (SSFLC) displays. Previous work from our groups suggests that this effect is due in part to unusually low orientational order due to steric repulsion between bulky tricarbosilane end-groups in a partially interdigitated bilayer structure, which forces hydrocarbon segments apart and creates free volume that is minimized by higher orientational fluctuations [2].

To further test this hypothesis and expand the scope of these unique materials, we intro-duced ethynyl spacers in the core structures of tricarbosilane-terminated mesogens. The isomeric 5-phenylpyrimidine and 6-phenylpyridazine model compounds 5PhP-6,6 and 6PhPz-6,6 have different mesomorphic properties due in large part to different core dipole moments (longitudinal vs. transverse). As shown in Fig. 1, the phenylethynyl analogues have lower melting points and, in the case of 6PhEPz-6,6, forms a N phase, but are other-wise mesomorphically similar. We recently synthesized the tricarbosilane-terminated 5-phenylethynylpyrimidine WL41-5 and 6-phenylethynylpyridazine WL53-6, both forming SmA and SmC phases, and characterized their mesomorphic and ‘de Vries-like’ properties by small angle and 2D X-ray scattering. A comparative analysis of these results, including reduction factor R, orientational order parameter S2 and effective length Leff, will be pre-sented in relation to the biaryl parent systems.

Figure 1. Mesomorphic properties of model compounds

References [1] C.P.J. Schubert et al., J. Mater. Chem. C 51, 12601 (2015). [2] C.P.J. Schubert et al., Soft Matter 13, 3307 (2017).


Oral 13

Exploration of short-oligomer nucleic acid liquid crystals

Gregory P. Smith1, Marco Todisco2, Tommaso P. Fraccia3, Giuliano Zanchetta2, Tommaso Bellini2, Noel A. Clark1

1University of Colorado Boulder, Department of Physics, Soft Materials Research Center, Boulder, U.S.A.

2ESPCI Paris, Intitut Pierre-Gilles de Gennes, Paris, France 3Università degli Studi di Milano, Dipartimento di Chimica,

Biochimica e Biotecnologie per la Medicina, Milan, Italy Liquid crystals formed by short DNA oligomers (length <20 nucleobases) dissolved in water are a case where the shape anisotropy necessary to stimulate liquid crystal formation is dependent on a molecular assembly hierarchy that involves building a complex chiral structure from hydrophobic, hydrophilic and highly specific hydrogen bonding interactions [1]. We advocate that the self-assembly properties of this class of materials would promote chemical selection for complementary nucleotide sequences and the ligation of oligomers (or monomers) by a suitable chemistry into longer polynucleotides [2], providing a clear benefit to the evolution of biological-type molecule populations in absence of functional life. Here, we aim to discuss new advances in our observations of materials in this class, including observations of mesophases formed by a 6-base RNA oligomer with inverted chirality [3], mesophases from mixtures of achiral sunset yellow with a 12-base DNA oligomer [4], and newly discovered mesophases from mixtures of the cyclic nucleotide monophosphates cAMP and cTMP.

References

[1] M. Nakata, G. Zanchetta, B. Chapman, C. Jones, J. Cross, R. Pindak, T. Bellini, N. Clark Science, 318, 1276-1279 (2007)

[2] T. Fraccia, G. Smith, G. Zanchetta, E. Paraboschi, Y.Yi, D. Walba, G. Dieci, N. Clark, T. Bellini, Nat. Comm. 6, 7463 (2015)

[3] M. Todisco, T. Fraccia, G. Smith, A. Corno, L. Bethge, S. Klussmann, E. Paraboschi, R. Asselta, D. Colombo, G. Zanchetta, N. Clark, T. Bellini, ACS Nano, 12, 9750-9762 (2018)

[4] J. Theis, G. Smith, Y. Yi, D. Walba, N. Clark, Phys. Rev. E., 98, 042701 (2018)

Acknowledgements The work presented here was funded by NSF MRSEC DMR-1420736 and NSF Grant DMR-1611272.

Figure 1. Phase diagram for self-complementary, inverted chirality RNA oligomer.

Oral 14

Figure 1. SH-SY5Ycells grown on LCE Foams

3D Liquid Crystal Elastomers as Long Term Responsive Scaffolds for Tissue Regeneration

M. Prévôt1, C. Webb2, S. Ustunel1,3, C. Zhu4, R.J. Clements2, and E. Hegmann*1-3 1Advanced Materials & Liquid Crystal Institute (AMLCI), 2Department of Biological Sciences

(BSCI), 3Chemical Physics Interdisciplinary Program (CPIP) Kent State University, Kent, OH USA

4Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA USA

Our unique series of smectic and nematic liquid crystal elastomers (LCEs) foams have shown to present very unique internal morphologies and are non-cytotoxic, making them suitable as longitudinal and multi-responsive cell scaffolds ideal for cell attachment, cell proliferation and most importantly cell alignment. Our LCE foams can be bestowed with highly tunable internal morphology permitting for better mass transport of nutrients for healthier, viable cells throughout the scaffold. The synthesis and design of our LCEs offers multiple degrees of freedom providing broad opportunities for exploring various chemical, biological, and physical aspects of scaffold-cell interactions. We will present how our scaffold platform for in vitro long-term three-dimensional (3D) LCE foams has proven to be non-cytotoxic to muscle (C2C12s), fibroblast (hDF), and neuroblastoma (SH-SY5Y) cells, supporting cell growth for over three months allowing for longitudinal cell function/metabolism studies. We will also show the importance of matching the mechanical properties of these scaffolds to various tissues.

Acknowledgements The authors wish to thank National Science Foundation for funding the NSF-REU Program (CHE-1659571), the Advanced Light Source, Berkeley. Beamline 7.3.3 of the Advanced Light Source is supported by the Director of the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The authors would also like to thank the Materials Characterization facility at AMLCI.

References [1] A. M. Lowe, and N. L. Abbott, Chem. Mater. 24, 746-758 (2012) [2] a) E.-K. Fleischmann, and R. Zentel, Angew. Chem. Int. Ed. 52, 8810-8827 (2013); b) H.

Finkelmann, and H. R. Brand, Handbook of Liquid Crystals, Vol. 3, 277-302 (2008); c) M. Camacho-Lopez, et al., Nat. Mater. 3, 307-310 (2004).

[3] a) A. Sharma, et al., Macromol. Biosci. 15, 200-214 (2015); b) A. Sharma, et al., Macromol. Biosci. 17, 1600278, (2017) c) Y. X. Gao, et al., ACS Macro Lett. 5, 14-19 (2016). M. Prévôt, et al., Soft Matter 14, 354-360 (2018).


Oral 15

Droplets of ferromagnetic nematic colloidal liquid crystal Min Shuai, Xi Chen, Cheol Soo Park, Joseph E. Maclennan, Matthew A. Glaser

and Noel A. Clark* Department of Physics and Soft Materials Research Center

University of Colorado Boulder, Boulder, Colorado 80309, USA

Concentrated suspensions of disk-shaped, ferromagnetic barium hexaferrite nanoplates in isotropic solvents exhibit a first-order transition from a paramagnetic isotropic (I) phase to a ferromagnetic nematic (NF) phase for sufficiently high volume fractions [1]. In samples prepared at a volume fraction within the I – NF coexistence range, it is possible to create metastable dispersions of NF droplets in an isotropic background. These oblate spheroidal droplets display a complex polar and chiral internal structure that results from the interplay of magnetostatic and nematic elastic free energy contributions. Magnetostatic interactions strongly favor tangential alignment of the NF magnetization field and the corresponding nematic director field along lines of latitude at the boundary of the droplet, but such a circumferential director configuration requires the formation of a +1 disclination line along the symmetry axis of the droplet, with a correspondingly large nematic elastic free energy cost. The formation of a disclination line is avoided through escape of the polar director field into the third dimension, giving rise to spontaneously chiral droplets whose handedness is determined by the sign of twist of the magnetization from the boundary of the droplet to the central axis. Coalescence of droplets leads to highly complex morphologies that depend on the polar and chiral structure of the constituent droplets. Oblate spheroidal NF droplets are also observed to transform spontaneously into toroidal droplets, where the chiral deformation is eliminated by formation of an isotropic hole through the center of the droplet.

Acknowledgements This work is supported by NSF MRSEC Grant DMR-1420736 and NASA Grant No. NNX17AC74G.

References [1] M. Shuai, A. Klittnick, Y. Shen, G. P. Smith, M. R. Tuchband, et al., Nature Communications 7, 10394 (2016). * Author for Correspondence: [email protected]

Oral 16

Interpretation of saddle-splay and the Oseen-Frank free energy in liquid crystals

Jonathan V. Selinger*

Department of Physics, Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44240, USA

We re-examine a classic question in liquid-crystal physics: What are the elastic modes of a nematic liquid crystal? The analysis uses a recent mathematical construction, which breaks the director gradient tensor into four distinct types of mathematical objects, representing splay, twist, bend, and a fourth deformation mode. With this construction, the Oseen-Frank free energy can be written as the sum of squares of the four modes, and saddle-splay can be regarded as bulk rather than surface elasticity. This interpretation leads to an alternative way to think about several previous results in liquid-crystal physics, including: (1) free energy balance between cholesteric and blue phases, (2) director deformations in hybrid-aligned-nematic cells, (3) spontaneous twist of achiral liquid crystals confined in a torus or cylinder, and (4) curvature of smectic layers.

(a) Bend B

(b) Bend B

(c) Twist T

(d) Splay S

(e) Biaxial splay Δij

(f) Biaxial splay Δij

Acknowledgements This work was supported by NSF Grant DMR-1409658.

Reference [1] J. V. Selinger, Liq. Cryst. Rev. 6, 129 (2018). * Author for Correspondence: [email protected]

Oral 17

A Database for Liquid Crystal Mixture Formulation

William N. Thurmes

Miyota Development Center of America, 2602 Clover Basin Drive Unit A, Longmont, CO 50803 USA

Creating liquid crystal mixtures tailored for a given application requires materials, measurements, science, and intuition. If designed correctly, a liquid crystal database can be an invaluable tool helping to bridge the gap between the formulator's concept and optimized liquid crystal mixtures. We herein delineate some of the criteria used to select a database management system, some of the database design concepts applied to create a working tool, and some of the programming used to make that tool more effective. We demonstrate a method of implementing a structure-activity relationship system, and illustrate the system with some of the mixtures made using it. We also discuss some of our strategies for formulating ferroelectric liquid crystals with a very wide smectic C* range, high driven cone angle, and fast switching speed.


Oral 18

Mechanotropic Elastomers

B. Donovan1, H. Fowler1, V. Matavulj2, T. White*1,2

1Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80309, United States

2Department Materials and Manufacturing Directorate, Air Force Research Lab, WPAFB, Dayton, OH 45433, United States

Liquid crystal elastomers (LCEs) are anisotropic polymeric materials. When subjected to an applied stress, liquid crystalline (LC) mesogens within the elastomeric polymer network (re)orient to the loading direction. The (re)orientation during deformation results in nonlinear deformation (referred to as soft elasticity) and strain hardening. Here, we uniquely explore mechanotropic phase transitions in elastomers with appreciable mesogenic content and compare these responses to LCEs in the polydomain orientation. The isotropic (amorphous) elastomers undergo significant directional orientation upon loading, evident in strong birefringence and x-ray diffraction. Functionally, the mechanotropic displacement of the elastomers to load is nonlinear, similar to polydomain LCEs. However, unlike polydomain LCEs, the isotropic elastomers rapidly recover after deformation. The mechanotropic orientation of the mesogens in these materials increase the relative toughness by nearly 1300% relative to a chemically similar elastomer prepared from wholly isotropic precursors.


Oral 19

Poster Abstracts

Developing liquid crystalline aerogels for thermal insulation of buildings

V. Cherpak1,2, B. Fleury1,2, E. Abraham1,2, J.B. ten Hove1,2, Q. Liu1,2, B. Senyuk1,2, J. De La Cruz1,2, A. Hess1,2, T. Lee1,2, I. I. Smalyukh1,2

1Department of Physics, Materials Science and Engineering Program, Soft Materials Research Center and Department of Electrical, Computer, and Energy Engineering, University of

Colorado, Boulder, CO 80309, USA 2Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and

University of Colorado, Boulder, CO 80309, USA Heating, ventilation, and air conditioning of buildings account for about 15% of the global energy consumption, but about 20% of this building-related energy is lost because of inefficient windows. Greenhouse emissions associated with producing and using this energy contribute substantially to climate change. Is there a solution to this challenging problem? Starting from the physical principles associated with energy loss through windows, I will describe our development of visibly transparent, infrared-reflecting, thermally super-insulating materials that may replace or retrofit the inefficient windowpanes of residential and commercial buildings. Using many demonstrations, I will discuss how production of such unusual transparent aerogels is aided by bacteria, with the source materials in the forms of waste of food industry and beer wort, to make such smart windows highly affordable. We will show how our aerogels can boost energy efficiency of windows and buildings in general.

Poster 1

Mirrorless lasing from three-dimensional photonic liquid crystalline blue phase II

Hyeon-Joon Choi, and Suk-Won Choi* Department of Advance Materials Engineering for Information and Electronics (BK21Plus),

Kyung Hee University, Yongin-shi, Gyeonggi-do, 17104, Korea Liquid crystals are a class of soft materials formed by nanoscale molecular self-assembly. Liquid crystalline-blue phase (LC-BP) exhibits a periodic structure and consequently give rise to photonic band structures for visible light. Thus, LCBPs are regarded as self-assembled three-dimensional photonic crystals (PCs). Through this PC property, lasing phenomena at the photonic band-gap (PBG) edge have been studied extensively. Herein, we prepared a dye-doped LC-BPs possessing extremely low threshold energy. First, three types of LCBP cells with different surface treatments were prepared and it was found that the surface treatment plays an important role in appearing LC-BPII. Next, the LC-BPII was stabilized by polymer networks. By means of the polymer-stabilizing, the temperature range of the LC-BPII was expanded. In addition, the intensity of the selective reflection at PBG was enhanced. Consequently, dye-doped LC-BPII laser with wide temperature range and low threshold energy was realized. Details will be reported in the FLC 2019.

Poster 2

Fréedericksz transition in ferromagnetic nematic filaments

Nathan Cobasko, Xi Chen, Min Shuai, Noel A. Clark*

Department of Physics and Soft Materials Research Center University of Colorado Boulder, Boulder, Colorado 80309, USA

Barium hexaferrite nanoplates at sufficiently high concentrations in 1-butanol spontaneously form a ferromagnetic nematic phase due to the interplay between Onsager excluded volume effects and magnetic dipole-dipole interactions [1]. We have discovered a rich variety of ferromagnetic structures, such as droplets, toroids, and filaments, which form in the isotropic background when the concentration of the nanoplates is within the isotropic-nematic phase coexistence region. Here, we demonstrate a Fréedericksz transition in these ferromagnetic filaments. In the absence of applied magnetic field, the local magnetization direction of the filaments is parallel to their long axes. When a magnetic field is applied parallel to the magnetization direction, the existing alignment of the nanoplates is reinforced and the shape of the filaments remain unchanged. However, when a sufficiently strong magnetic field is applied antiparallel to the magnetization direction, an undulation instability sets in and the filaments form wavy structures.

Figure 1. Ferromagnetic nematic filaments in isotropic background viewed between crossed polarizers. (a) Filaments magnetized along their long axes in the absence of applied field. (b) When a magnetic field above a threshold is applied antiparallel to the magnetization direction of the filaments, they start to undulate and form wavy structures.

Acknowledgements This work is supported by NSF MRSEC Grant DMR-1420736 and NASA Grant No. NNX17AC74G.

References [1] M. Shuai, A. Klittnick, Y. Shen, G. P. Smith, M. R. Tuchband, et al., Nature Communications7, 10394 (2016).


Poster 3

Localizing Genesis in Polydomain Liquid Crystal Elastomers

H. Fowler1 and T. J. White1*

1Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, USA

Liquid crystal elastomers (LCEs) exhibit fascinating physical properties. Recent research has focused extensively on the utility of these stimuli-responsive materials as actuators. Here, we are concerned with their nonlinear mechanical deformation to load. Previously, we reported on the use of spatial variations in alignment in order to localize the material response to load [1,2]. These prior efforts are based in part on planar orientations which dictate directionality to the deformation. Polydomain LCEs, having no long-range order, naturally exhibit omnidirectional nonlinear mechanical deformation. Prior research indicates that the stress-strain response of polydomain LCEs is correlated to their genesis, i.e. polymerization in either the isotropic or nematic state [3]. Here, we develop a materials chemistry and processing method involving the photopolymerization of acrylate and thiol comonomers to prepare main-chain, polydomain LCEs in which the genesis during polymerization can be locally varied. Accordingly, we prepare a homogenous composition of polydomain LCE with spatial variation in genesis. Reaction kinetics were studied via real-time FTIR, and global mechanical characterization included tensile testing, creep recovery experiments, and dynamic mechanical analysis. Local mechanical characterization was visualized with digital image correlation. Complex patterns were imprinted (Figure 1A) and shown to localize the mechanical response in the material (Figure 1B).

References [1] T. H. Ware, J. S. Biggins, A. F. Shick, M. Warner, and T. J. White, Nat. Commun. (2016).[2] A. D. Auguste, J. W. Ward, J. O. Hardin, B. A. Kowalski, T. C. Guin, J. D. Berrigan, and T. J.

White, Adv. Mater. 30, 1-6 (2018). [3] K. Urayama, E. Kohmon, M. Kojima, and T. Takigawa, Macromol. 42, 4084-4089 (2009).


Figure 1. (A) Complex patterns can be created within a single monolith of polydomain LCE by regulating the genesis of polymerization. (B) Digital image correlation visualizes the mechanical response is primarily localized to the isotropic genesis segments (black regions) in a patterned chevron.

Poster 4

Fast electro-optical switching of dichroic dye-doped antiferroelectric liquid crystals without polarizers

Veridiana G. Guimarães1,2,3, Junren Wang1, Steven Planitzer5, Katalin Fodor-Csorba6, Rafael S. Zola2,4, Antal Jákli*1,5,6

1Liquid Crystal Institute, Kent State University, Kent, OH 44242 USA 2Departamento de Física, Universidade Estadual de Maringá, Avenida Colombo 5790, 87020-

900 Maringá, Paraná, Brazil 3CAPES Foundation, Ministry of Education of Brazil, Brasília, DF 70040-020, Brazil

4Departamento de Física, Universidade Tecnológica Federal do Paraná, Rua Marcílio Dias 635, 86812-460 Apucarana, Paraná, Brazil

5Department of Physics, Kent State University, Kent, OH 44242 USA 6Institute for Solid State Physics and Optics, Wigner Research Center for Physics, Hungarian

Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary

Dye-doped guest-host nematic (N), cholesteric (N*) and polymer dispersed liquid crystals (PDLC) have been extensively used for polarizer free electro-optical devices. In all these displays, the director is switched between random, helical or planar (dark state) and homeotropic (bright state) alignments. In all these devices is the switching time is well above 1 ms.

Here we demonstrate electro-optical switching of a room temperature dye-doped antiferroelectric (SmCA*) liquid crystal mixture, both in single layer with the use of one polarizer, and in double layer configurations without the need of any polarizer. We achieved uniform alignment on macroscopic scale of thin cells with the combination of proper surface alignment and electric field treatment. [1] We also show that one could get either normally dark or bright states. Normally dark states can be useful in number of applications such as in privacy windows or smart refrigerators. A normally transparent display has applications in plethora of other areas, such as navigation systems built in windshields, in goggles, or smart windows.

[1] V. G. Guimarães, J. Wang, S.Planitzer, K. Fodor-Csorba, R. S. Zola,and A. Jákli, Phys. Rev. Appl. 10,064008 (2018).* Author for Correspondence: [email protected]

Figure 1. Illustration of the switching of double layered AFLC guest-host system (CS4000+5wt% S-428, 5 µm gap thickness and planar alignment) without polarizers. (a) Rubbing directions of individual films make 90degrees with each other (along the edges of the electrodes)(a) picture when U=30 V, f=80 Hz square wave voltage isapplied; (b) Field is OFF; (c) Time dependence of theapplied voltage (left axis, black line) and of thetransmission (right axis, red squares). (d and e): Images ofparallel cells in the antiferroelectric OFF state and (d) andin the ferroelectric ON state (e).

Poster 5

Electrooptical characterization of zwitterionic derivatives of [closo-CB9H10]- and [closo-CB11H12]- anions

Andrienne C. Friedli1, Jacek Pecyna1, Rafał Jakubowski2, Muhammad O. Ali1, Anna Pietrzak,1 and Piotr Kaszyński*1,2

1 Department of Chemistry, MTSU, Murfreesboro, TN 37132, USA2 Centre of Molecular and Macromolecular Studies, PAS, 90-363 Łódź, Poland

Anions [closo-1-CB11H12]- and [closo-1-CB9H10]- (A and B, respectively) are attractive structural elements for liquid crystals. Substitution of these clusters with onium fragments leads to zwitterions with substantial dipole moments, which are of interest for the design of materials for LCD applications. In this context we have been conducting systematic investigation of polar liquid crystalline derivative of A and B [1]. Previously we demonstrated a series of esters 1 and characterized their performance as low concentration additives to nematic hosts [2]. To lower rotational viscosity of the material, we have designed compounds in which the COO linking group in 1 is replaced with the CH2CH2 group in 2.

Herein we present the synthesis of derivatives 1 and 2 and provide their comparative analysis with optical, thermal and dielectric methods in the pure form and in binary mixtures with a nematic host. Experimental data are augmented with results of DFT calculations.

Acknowledgements Support was provided by the NSF (DMR-1611250 and CHE- 1626549), National Science Center Poland (2015/17/B/ST5/ 02801) and FNP (TEAM-3/2016-3/24) grants.

References [1] P. Kaszyński “closo-Boranes as structural elements for liquid crystals” in Handbook of BoronScience”, N. S. Hosmane and R. Eagling, Eds.; World Scientific, London, 2018, Vol 3, pp 57–114.[2] Pecyna, J.; Kaszyński, P.; Ringstrand, B.; Bremer, M. J. Mater. Chem. C, 2014, 2, 2956; Pecyna, J.;Denicola, R. P.; Gray, H. M.; Ringstrand, B.; Kaszyński, P. Liq. Cryst., 2014, 41, 1188; Pecyna, J.;Ringstrand, B.; Kaszynski, P. J. Mater. Chem. 2010, 20, 9613.


Poster 6

Novel Nanofilament Phase Formed by Carbosilane Terminated Bent-Core Mesogens

David M. Walba1, Eva D. Korblova1,Rayshan Visvanathan2, Yongqiang Shen2, Keri Graber2, Michael Tuchband2, Maria Kolber1, Edward Guzman1, Joseph E. Maclennan2, Matthew A.

Glaser2, Ren-Fan Shao2 and Noel A. Clark2 1Department of Chemistry and 2Department of Physics, Soft Materials Research Center,

University of Colorado, Boulder, CO 80309, USA

The first banana SmAPF mesogen designed in our group was W586 [1], a non-tilted (orthogonal), achiral, biaxial, and spontaneously polar fluid smectic. The following material, W623, first synthesized by Tao Gong in our laboratory [2], serves as a prototypical SmAP material exhibiting interesting and useful electrooptics. In teflon-aligned glass cells, upon application of an electric field, modulation of the birefringence was observed without rotation of the apparent optic axis. Analog V shaped-switching with optical latching in this material makes it attractive for potential electrooptic applications [3,4].

Here we describe the novel, non-switchable, low temperature nanofilament phase of W623, and several similar molecules. Members of a homologous series with n-carbon alkyl spacers (5 < n <11) between the molecular core and the tricarbosilane terminating group have a general phasesequence of Iso – SmA – SmAP – filamentary phase. We have characterized the filamentary phase using polarized optical microscopy, freeze-fracture transmission electron microscopy, and x-ray scattering measurements. We found that the number of carbons in the alkyl spacer plays a pivotal role in the formation of filamentary structures. For shorter alkyl spacers (n < 8), the bent-core molecules retain lamellar ordering upon cooling from the SmAP phase, while homologs with n < 9 have a strong tendency to assemble into bundles of nanofilaments. A proposed structural model for the nanofilament phase will be presented.

Acknowledgements This work was supported by the Soft Materials Research Center under NSF MRSEC Grant DMR-1420736 and NSF MRSEC Grant DMR-1710711.

References [1] Reddy et al., Science 332, 72-77 (2011).[2] Gong, T., Ph.D. Dissertation, Univ. of Colorado Boulder, 2011[3] Shen et al., Physical Review E 84, 020701 (2011).[4] Walba US 9,187,500 B2, Nov. 17, 2015


Poster 7

Consideration of distorted in-plane and out-of-plane retardation switching on certain types of smectic liquid crystals

A. Mochizuki

i-CORE Technology, LLC. Louisville, Colorado, USA

Some chiral smectic C phase and smectic C phase liquid crystals show distorted retardation switching behaviors in terms of in-plane and out-of-plane retardation during their switching [1]. Here the meaning of “distorted retardation” is non-symmetrical retardation switching between in-plane and out-of-plane retardation. A typical ferroelectric liquid crystal panel shows symmetric retardation switching between in-plane and out-of-plane retardation. In some smectic liquid crystal panel cases, even in-plane only retardation switching was reported [2]. Non-symmetric retardation switching is also observed not only in-plane/out-of-plane retardation switching, but also its dependence of the applied electric field polarity on symmetricity of in-plane/out-of-plane ratio as shown in Figure 2 bellow. A clear separation between in-plane and out-of-plane retardation dynamic switching was measured using PEMs [2]. A simpler means to estimate in-plane/out-of-plane retardation switching is measured in comparison with under crossed Nicol and crossed Nicole with quarter waveplates optical set-ups as shown their results both in Figures 1 and 2. Observation of dynamic retardation switching behaviors in some smectic liquid crystals would be an effective means to explore their smectic layer structure and driving torque origin. In this paper, some influence of retardation switching behavior on layer structure stability and conceivable driving torque origin of smectic liquid crystal panels are discussed.

Figure 1 Under crossed Nicol configuration. Figure 2 Crossed Nicol with quarter waveplates References [1] “Liquid Crystals” Edited by Irina Carlescu, Chapter 4, IntechOpen, London, UK, 2018. [2] A. Mochizuki, “Molecular tilting effect on Smectic liquid crystal sub-phase stability from its retardation switching behavior”; Journal of Molecular Liquid, Vol. 267, pp. 456-468 (2018). *Author for Corresponding: [email protected]

2 ms

Time (ms)

Voltage

Light intensity

2 ms

Time (ms)

Voltage

Light intensity

Poster 8


Simulation Studies of Ferromagnetic Nematic Fluids

J. Papaioannou, M.A. Glaser*Department of Physics and Soft Materials Research Center, University of Colorado Boulder

Boulder, Colorado, USA

Conventional ferrofluids, produced by suspending magnetic nanoparticles in a solvent, exhibit dramatic response to applied magnetic fields, but are macroscopically paramagnetic. Recently, a macroscopically ferromagnetic fluid phase, the ferromagnetic nematic phase, has been discovered in fluid suspensions of ferromagnetic nanoplates [1,2]. These experiments necessitate a more thorough theoretical understanding of the phase that can address a variety of questions posed by the new results. By further developments on past simulation studies, Monte Carlo simulations of oblate spherocylinders with distributions of dipoles along their surfaces provides a key model for studying the ferromagnetic nematic phase. Long-range electromagnetic interactions are treated using the Ewald summation method, with newly derived modifications for handling distributions of dipoles as opposed to point dipoles. Free energy differences are estimated using the Multiple Bennett Acceptance Ratio (MBAR) method, which are used to calculate the free energy contours in order to construct phase diagrams for the model.

Acknowledgements This work was supported by the Soft Materials Research Center under NSF MRSEC Grant DMR-1420736.

References [1] Mertelj, D. Lisjak, M. Drofenik, and M. Čopič, Nature 504, 237–241 (2013).[2] M. Shuai et al., Nature Comm. 7, 10394 (2016).


Poster 9

Multi-level chirality in smectic phases made of achiral

dimeric molecules

Damian Pociecha1, Mirosław Salamończyk1,2, Nataša Vaupotič3,4, Rebecca Walker5, John M. D. Storey5, Corrie T. Imrie5, Cheng Wang2, Chenhui Zhu2, Ewa Gorecka1

1University of Warsaw, Faculty of Chemistry, Żwirki i Wigury 101, 02-089 Warszawa, Poland. 2Lawrence Berkeley National Laboratory, Advanced Light Source, 1 Cyclotron Rd, Berkeley, CA 94720, USA. 3Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia. 4Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia. 5Department of Chemistry, King’s College, University of Aberdeen, Aberdeen AB24 3UE, UK.

Chirality of a structure is a natural consequence of breaking the mirror symmetry on a level of

building blocks – molecules. However, recently several examples of chiral structures formed by

achiral molecules were reported, among them tilted polar B2 phase and twist-bend nematic phase.

Here we present complex systems built of achiral dimeric molecules that show not only both types

of structural chirality typical for mentioned above phases: layer chirality and helicity of a basic

repeating unit, but additionally two other levels of structural chirality: mesoscopic helix and helical

filaments [1]. Similarly to many biological systems, there is a coupling between chirality at

different levels in the studied system.

To resolve multi-level structure of phases a combination of experimental technics were applied,

including resonant soft x-ray diffraction measurements, optical studies and theoretical modelling.

[1] M. Salamończyk, N. Vaupotič, D. Pociecha, R. Walker, J. M. D. Storey, C. T. Imrie, C. Wang, C. Zhu, Ewa Gorecka, Multi-level Chirality in Liquid Crystals Formed by Achiral Molecules, Nat. Commun. 10, 922 (2019)

Poster 10

Towards elucidating the electrochemical interaction of ions and structurally chiral polymer stabilized networks in electrically

tunable filters

Brian P. Radka*1, Timothy J. White1

1Department of Chemical and Biological Engineering, University of Colorado Boulder

The cholesteric liquid crystalline phase self-organizes into a helical structure. In the planar orientation, the periodicity naturally exhibits a Bragg Reflection. In prior research, we have developed a polymer/liquid crystal materials system capable of dynamic reconfigurability when subject to electric field, observable as red-shifting tuning, blue-shifting tuning, or bandwidth broadening. Our recent research activities have focused on further elucidating the fundamental electrochemical response of the ion-medicated deformation of the polymer stabilizing network in the cholesteric phase. Specifically, incorporating known ionic traps into the polymer stabilized network, we have further improved the electro-optic response. The correlated influence of photopolymerization conditions, crosslink density, and ionic impurities will be discussed. *Author for Correspondence: [email protected]

Poster 11

Investigation of the Relationships Between Spontaneous Polarization and Tilt Angle in Ferroelectric and Antiferroelectric Liquid Crystals

Zbigniew Raszewski, Wiktor Piecek, Leszek Jaroszewicz, Rafał Mazur, Przemysław

Morawiak, Katarzyna Gaładyk, Jerzy Zieliński

Military University of Technology, 00-908 Warsaw, Poland, E-mail: [email protected]

A b s t r a c t

Spontaneous polarization (PS), tilt angle (), helical pitch (p) and densytometric (), refractometric, dielectric characteristics versus temperature (T) have been measured for chosen Ferroelectric Liquid Crystals (FLC) and some Ferroelectric Liquid Crystals Mixture (FM) with different chiral dopants and their concentrations in investigated FM. These studies were supported by spectroscopic, an X-ray, Differential Scanning Calorimetry (DSC) measurements and microscopic observations. On the base of our measurements of extraordinary ne(T) and ordinary no(T) refractive indices, parallel ||(T) and perpendicular ⊥(T) components of electric permittivity tensor of FLC smectic layers, supported by density (T) measurements and computer modelling, the molecular dipole moment (), longitudinal (l) and transverse (t) molecular polarizabilities as well as the angles (, 0) between the vector and main long (n) and short (l) molecular axes of inertia for chiral molecules of FLCs have been calculated.

Knowing the molecular parameters (, , 0, l, t) and the molecular density number N of chiral molecules that build the given tilted ferroelectric smectic phase (SmC*) characterized by its state parameters (T) and p(T), the spontaneous polarization PS(T) has been calculated. PS(T) was described as the vector sum of components of molecular (permanent and induced) dipole moment ⊥ perpendicular to tilt direction. To do it the Zeks rotational potential modified by us has been applied.

After comparing the PS(T) taken from experiments and obtained from our theoretical approximations one can state that the sign and the magnitude of spontaneous polarization is described by

• mutual relations between coupling forces expressed by the dipolar (a1), the quadrupolar (a2) and flexoelectric (a3) coupling parameters of rotation potential,

• their relation to the molecular parameters (, l, t), • the structure of chiral molecule where characteristic molecular axes d (chiral) and b

(quadrupolar) form the angles Ω and Г with the short l axis of inertia and vector is described by angles of and 0,

• medium structure of SmC* characterized by (T) and p(T) and • temperature T.

The relationships between spontaneous polarization PS(T) and tilt angle (T) in different FLCc and AFLC layers ware discussed due to:

• the number N and molecular parameters (l, t, ) of chiral molecules, • structure of chiral molecule described by number and positions of chiral centers and

the characteristic angles Ω, Г, and 0 inside it, • the geometrical relations (the angle ) between the direction of the long axis of the

inertia chiral molecule and the axis of its polarizability elpsoid, • the contribution of dipolar (a1) and quadrupolar (a2) terms in the rotational potential, • differences in the order of appearance of ferroelectric smectic phases in FLCs and

AFLCs.

Poster 12


Investigations of oxadiazole-based bent-core liquid crystals containing strongly polar lateral groups

M. Riley1, B. Bordokas1, F. Vita2, F. C. Adamo2, O. Francescangeli2, and E. Scharrer*1 1Department of Chemistry, University of Puget Sound, Tacoma, Washington

2Dipartimento di Scienze e Ingegneria della Materia, dell’Ambiente ed Urbanistica, Università Politecnica delle Marche, Ancona, Italy

In 2009, ferroelectric switching was observed in the nematic phase of a bent-core liquid crystal containing a 1,2,4-oxadiazole core. It was hypothesized that this response occurred due to a field induced re-ordering of polar cybotactic clusters that constitute the nematic phase, and that this was related to field induced biaxiality [1]. More recent studies on a different class of 1,2,4-oxadiazole-based liquid crystals also found ferroelectric behavior [2]. Notably, no ferroelectric properties were found in an analog containing a 1,3,4-oxadiazole moiety.

1,3,4-oxadiazole-based liquid crystals have been highly studied since the discovery of a potential biaxial nematic phase in these derivatives in 2004 [3]. Our efforts have focused on studying the effects of lateral substituents on the phase behavior [4]. This has proved a successful way of accessing the N phase at low temperatures with many of the derivatives possessing three lateral groups supercooling to room temperature in the N phase. Additionally, in these latter derivatives, a splitting of the diffuse wide angle X-ray diffraction pattern occurs which is consistent with local biaxial ordering [5].

A possible explanation for the lack of observed ferroelectricity in the 1,3,4-oxadiazole derivatives is that, unlike the 1,2,4-oxadiazole compounds, they do not possess an off-axis dipole moment. Given this hypothesis, we sought to prepare 1,3,4-oxadiazole analogs that have a strong off-axis dipole by incorporating a lateral group that is highly polar. We have prepared a series of such compounds and will report details on their synthesis and routine phase behavior, as well as more sophisticated characterization.

Acknowledgements Financial support for ES, MR, and BB was provided NSF DMR-1709148.

References [1] O. Francescangeli et al, Adv. Funct. Mater. 19, 2592-2600, (2009). [2] G. Shanker et al, Adv. Funct. Mater. 22, 1671-1683, (2012). [3] L. A. Madsen et al, Phys. Rev. Lett. 92, 14505, (2004). [4] J. Nguyen et al, Liq. Cryst. 42, 1754-1764, (2015). [5] F. Vita et al, Chem. Mater. 26, 4671-4674, (2014). * Author for Correspondence: [email protected]

Poster 13

Color reconfiguration in liquid crystalline elastomers K.R. Schlafmann1, M.T. Brannum2, T.J. White1

1Department of Chemical and Biological Engineering, University of Colorado – Boulder,

Boulder, CO 2Materials and Manufacturing Directorate, Air Force Research Laboratory

Wright-Patterson Air Force Base, OH

Liquid crystalline elastomers (LCEs) have been a topic of significant interest, largely motivated by their compelling performance as material actuators. Here, we detail distinctive optical reconfiguration of solid LCE compositions, based on the cholesteric and blue phases. Both phases are retained in the LCE composition and exhibit selective reflection attributable to the periodic superstructure. Thermochromic reconfiguration of the selective reflection is detailed, associated with dimensional and phase changes. Considerations in the synthesis and preparation of these materials will be a significant focus of this contribution.


Poster 14

Elastic and electrostatic multipoles in liquid crystals

B. Senyuk1, H. Mundoor1, B. Fleury1, M. Tasinkevych2,3 and I. I. Smalyukh4,5 1 Department of Physics and Soft Materials Research Center, University of Colorado,

Boulder, CO 80309, United States 2 Max-Planck-Institut für Intelligente Systeme, Stuttgart, Germany

3 Centro de Física Teórica e Computacional, Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal

4 Department of Electrical, Computer, and Energy Engineering, Materials Science and Engineering Program, University of Colorado, Boulder, CO 80309, United States

5 Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, CO 80309, United States

Achieving and exceeding diversity of colloidal analogs of chemical elements and molecules as building blocks of matter has been one of the central goals and challenges of colloidal science. We introduce physical design principles allowing us to define high-order elastic multipoles emerging when colloids with controlled shapes and surface alignment are introduced into a nematic liquid crystal. Combination of experiments and numerical modeling of equilibrium field configurations using a spherical harmonic expansion allow us to probe elastic multipole moments, bringing analogies with electromagnetism and a structure of atomic orbitals. We show that diversity of elastic colloidal atoms can far exceed that of known chemical elements. To study the interplay between elastic and electrostatic multipoles we also use colloids having electric monopole and dipole moments on their own. * Author for Correspondence: [email protected]

Poster 15


Properties of nanodoped surface stabilized ferroelectric liquid crystals under electric and magnetic fields

H. Singh1, D. Dass2, Swami V. Reddy2, G. Kendu2, and D. Kaushik2 1 Department of Mechanical Engineering, EIILM University, Sikkim, India 737101

2 Department of Physics, GKU Engineering & Technology, Salem, India 636001 Surface stabilized ferroelectric liquid crystal (SSFLC) doped with ferroelectric nanoparticles shows interesting polarization and orientational behavior in external fields. In this work we study the behavior of a nanodoped SSFLC subjected simultaneously to electric and magnetic fields. The threshold fields and maximum deviation of the polarization vectors for a pure and nanodoped system are calculated and the strong influence of spontaneous polarization on magnetic threshold field is revealed as well as on electric field.


Poster 16

Intricate behavior of 4-base nanoDNA sequences: an intersection between condensed matter and RNA world

G. P. Smith1, T. P. Fraccia2, M. Todisco2, C. Zhu3, T. Bellini2, D. M. Walba4 and N. A. Clark1,* 1Department of Physics and Soft Materials Research Center, University of Colorado, Boulder,

CO, 80309-0390, 2Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università di Milano, via Fratelli Cervi 93, I-20090 Segrate (MI), Italy, 3Advanced Light Source, Lawrence

Berkeley National Laboratory, Berkeley, CA 94720 USA, 4Department of Chemistry and Soft Materials Center, University of Colorado, Boulder, CO, 80309

nanoDNA are short sequence DNA oligomers having ~20 or fewer A, T, G or C nucleotide bases, that can form liquid crystal (LC) phases if they have the appropriate combination of complementarity, hydrophobic end-stacking, and/or sticky-end hydrogen bonding (G sticking to C or A to T) when dissolved in water [1]. nanoDNAs are of interest in an origins-of-life context because their LC phases can effectively catalyze DNA autoligation and create longer sequences from shorter ones in the absence of protein catalysis [2]. As a bridge between ligation mediated by intermediate length nanoDNA oligomers and LC formed from single-base monomers [3], we pursue a general characterization of the self-assembly and phase behavior of particularly short 4 base DNA sequences, including GCCG, GTAC, and ATTA, as a function of both concentration and temperature. GCCG, which assembles into Watson-Crick duplexes by 2X2 sticky-end base pairing, and which also forms G-quartets, exhibits coexisting LC, crystalline and glassy phases. Watson-Crick duplexes appear to dominate in fresh GCCG mixtures, but tend to settle into a more complicated crystal structure over time. The crystal structure is a network of sites on a cubic lattice where struts containing 6 GCCG oligomers that are capped with free guanines at the terminals can assemble by g-quartet formation into a body centered lattice [Figure 1]. At especially high concentrations, GCCG exhibits a reentrant isotropic phase which we interpret as a glassy G-quartet mediated structure.

Acknowledgements: This work supported by NSF Biomaterials Grant DMR-1207606, NSF MRSEC Grant DMR-1420736. ALS Beamline 7.3.3 is supported by U.S. DoE under contract No. DE-AC02-05CH11231.

*e-mail of Correspondence Author: [email protected]

Figure 1. Schematic of G-quartet body centered lattice.

References:

[1] Nakata M et al (2007) Science 318, 1276, DOI: 10.1126/science.1143826

[2] Fraccia TP et al. (2015) Nature Communications 6:6424, DOI: 10.1038/ncomms7424.

[3] Smith GP et al (2017) Origins XXVIII, Abstract #4185.

Poster 17

Improvement of Electro-optical Response of Vertical Aligned Ferroelectric Liquid Crystals

Y.Takanishi1,2, I.Nishiyama2,3, J. Yamamoto1,3

1 Graduate School of Science, Kyoto University, Kyoto, Japan 2JST-CREST, Japan

3DIC Corporation, Saitama, Japan

Vertically aligned ferroelectric liquid crystals (VA-FLCs) can be fabricated without no rubbing process, and there is also the advantage that the appearance of spontaneous defects due to the layer shrinkage is prevent. In particular, deformed helix FLC(DH-FLC) mode with short helical pitch is expected to have high contrast and fast response(< 100 µsec), and is attractive in terms of applications such as displays and light modulation. However, it is a disadvantage that the driving voltage becomes significantly high (> 10 V/µm). Recently, Yamamoto et al. succeeded in decreasing the driving voltage of VA-FLCs by introducing the liquid interfaces using the isotropic-SmC* phase separation induced by the isomerization of an azo dye[1]. We call these liquid interfaces slippery interfaces, on which the liquid crystalline molecules can rotate without anchoring and hence the high transmittance is obtained under a low driving voltage. In addition, we stabilized the liquid interfaces by polymerization of binders to form gel interfaces. In this paper, we introduced an ionic liquid gel of VA-FLC in IPS cells. Ionic liquid has high conductivity, and it is expected that the ionic liquid gel works as slippery interface and also a kind of wall of electrode if it is fix the ionic liquid gel on the ITO electrode of IPS cell.

Figure 1 shows the electro-optic response of VA-FLC with ionic liquid gel in 3.5 μm-thick IPS cell under the applied stepwise electric field (+E → 0 → –E→ 0) at 50°C, depending on the applied fieldtreatment time at 70°C. It is found thattransmittance after applied electric-fieldtreatment for long time at above sol-geltransition temperature (70°C) greatlyincreases compared to that before appliedelectric field treatment. This resultsuggests the reduction of driving voltageby introduction of ionic liquid gels.

Acknowledgements This study was supported by JST-CREST（Grant No. JPMJCR1424）.

[1] J. Yamamoto and I. Nishiyama, Proc. SPIE 10735, Liquid Crystals XXII, 107350V(2018).

* Author for Correspondence : [email protected]

Fig.1 : Electro-optic transmittance of VA-FLC with ionic liquid gel in 3.5 μm-thick IPS cell under the applied stepwise electric field (+1.5V/μm → 0 → –1.5V/μm→ 0) of 10 Hz at 50°C. “t” indicates the applied field treatment time at 70°C.

Poster 18

Development of Bistable Ferroelectric Liquid Crystals

William N. Thurmes, Cory S. Pecinovsky, Christopher Gabriel, Michelle Livingston, R. Scott Hathcock, Bruce Gamache

Miyota Development Center of America, 2602 Clover Basin Drive Unit A, Longmont, CO 50803 USA

The main commercial use for Ferroelectric Liquid Crystals (FLCs) is in fingernail-sized displays used primarily as optical viewfinders for digital cameras and camcorders. Companies developing devices for nascent virtual and augmented reality (VR/AR) markets are also showing interest in FLC displays. Because of required DC balancing, the typical driving scheme for these FLC displays includes a period with a positive image during which illuminating LEDs are turned on, balanced by a period driving the negative image with no illumination. A bistable FLC cell would obviate the need for the negative image period, thus allowing the positive image to be displayed for a higher percentage of the time, resulting in a brighter display. This would be advantageous in the VR/AR market, where optical output is a key requirement.

We are developing new FLC mixtures that are bistable when used in cells having obliquely deposited SiO2 layers. Approaches for solving several problems encountered in this development are herein presented. Among these problems are zigzags that form when driving below room temperature, hysteresis in the switching threshold depending on whether cells have been previously driven to bistability, and the lack of live cells to use in demonstrating FLC bistability.


Poster 19

Polar Discotic Liquid Crystals and Semiconductivity

Ke-Qing Zhao1, Hirosato Monobe2, Bertrand Donnio3

1. College of Chemistry and Materials Science, Sichuan Normal University, Chengdu 610066 (China).

2. Inorganic Functional Materials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577 (Japan).

3. Institut de Physique et Chimie des Materiaux de Strasbourg (IPCMS), CNRS-Universite de Strasbourg (UMR 7504), 23 rue du Loess, BP 43 67034 Strasbourg Cedex 2 (France)

Liquid crystals (LCs) as unique ordered fluids have been widely used in

information displaying industry in last half-century. LCs as a kind of novel organic semiconductors are now attracting more and more attentions of researchers. For LC semiconductors, self-organizing polycyclic aromatic hydrocarbon (PAH) cores play the role of electronic charge transporting channel, the peripheral alkyl chains promote mesophase formation. LC semiconductors are cost-effect, and can be fabricate to large areas, flexible film electronic devices, such as organic field-effect transistors (OFETs), photovoltaic solar cells (PSCs), organic light-emitting diodes (OLEDs), and electronic sensors. The progress of synthetic chemistry greatly benefits the discovery of LC semiconducting materials.

Charge carrier mobility µ is the key parameter of LC semiconductors, and the value of µ has close relationship with the order degree of LC phase, and order degree is mainly determined by chemical structures of liquid crystalline molecules. We have synthesized polar DLCs with extended polycyclic aromatic hydrocarbon (PAH) [1], donor-acceptor-donor triad DLCs [2], core-fluorinated and chlorinated DLCs [3]. The mesophases have been characterized by POM, DSC, and SAXS techniques. The charge carrier mobility has been measured by transient photocurrent time-of-flight (TOF) technique. The correlate relationship of mesophase order degree and charge carrier mobility is proposed. The result can be applicate for further LC semiconducting material designing.

References [1] K. Q. Zhao, H. Monobe, B. Donnio. J. Mater. Chem. C, 5, 669 (2017). [2] K. Q. Zhao, H. Monobe, B. Donnio. Dyes Pigm. 143, 252 (2017). [3] K. Q. Zhao, H. Monobe, B. Donnio. Chem. Eur. J. 21, 10379 (2015). * Author for correspondence: [email protected]

Poster 20


Chiral dopant induced properties of a working ferroelectric smectic mixtures

Jerzy Zieliński, Wiktor Piecek, Leszek Jaroszewicz, Katarzyna Gaładyk, Przemysław

Morawiak, Michał Czerwiński, Rafał Mazur, Zbigniew Raszewski

Military University of Technology, 00-908 Warsaw, Poland,

E-mail: [email protected]

A b s t r a c t

The aim of presented research was an assessment of an influence of dopants with one and two

chiral centers on the physical and electrooptical properties of a ferroelectric smectic mixture

which is a key factor of elaboration of working ferroelectric liquid crystal (FLC) mixtures of

tailored properties, especially with the tilt angle value near 22.5 in a broad temperature

range. Testing FLC mixtures were prepared using the common pyrimidine based parent

mixture F4 doped with three different chiral dopants. The thermal characteristic of the optical

tilt angle OPT, tilt angle calculated by means of X-ray method XRD, spontaneous polarization

PS, switching times 10-90, rotational viscosity and layer spacing d of obtained FLC

mixtures were studied. Based on the above measurements and computer calculations the

relationship between PS and OPT were discussed. Electrooptical performance of the Surface

Stabilized Ferroelectric Liquid Crystal (SSFLC) structures were observed. The relation

between the molecular parameters of chiral dopants and the chemical and physical properties

of obtained FLC mixtures are considered in frames of the extended microscopic model of the

spontaneous polarization in FLCs.

Poster 21


Sponsors - University of Colorado Boulder program.pdfAdvanced Materials and Liquid Crystal Institute, Kent State University, USA 3D liquid crystal elastomers as long term responsive

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