M4 COLLOIDS SYMPOSIUM · deposition methods: 1) equilibrium physisorption from solution in a model oil, and 2) Langmuir-Blodgett (LB) deposition. Our shear measurements demonstrate

M4 COLLOIDS SYMPOSIUM 2019 Hosted By Bath University

Supported by:

Schedule 09:30-10:00 Arrival

Session 1 – Chair: Saffron Bryant

10:00-10:10 Brief welcome talk

10:10-10:30 Nicholas Taylor Ultralow friction mediated by centipede copolymers

under confinement

10:30-10:50 Henry Symons Dimensional and morphological control of perylene

diimide-based supramolecular polymers

10:50-11:10 Davide Califano A self-activated antimicrobial cellulose film producing

hydrogen peroxide via enzyme coupled reaction: a promising material for wound treatments

11:10-11:30 Dajana Gubala Characterisation of surface morphology and

nanomechanical properties of synthetic fibres. From nanoscopic fibre structure to sensation of touch

11:30-11:50 Christian Romero 3D-printed Power – Functional Polymers for Soft

Robotics

11:50-13:10 Lunch + poster session

Session 2 – Chair: Zakir Hossain

13:10-13:30 Vincenzo Calabrese Charge-driven interfacial gelation of cellulose

nanofibrils across the water/oil interface

13:30-13:50 Silvia Ruscigno Zipper polyelectrolyte brushes from interfacial

coacervation

13:50-14:10 Han Yin

Self Assembly of Alpha-Synuclein Fibrils

14:10-14:30 Andrew McCluskey Automating reflectometry reduction and analysis at

Diamond Light Source

14:30-15:00 Tea and coffee break + Posters

Session 3 – Chair: Han Yin

15:00-15:20 Lauren Matthews Molecular Mechanisms in Hydrogen-Bonding Rich

Non-Aqueous Solvents

15:20-15:40 Sian Fussell Reversible temperature-controlled gelation in

mixtures of pNIPAM microgels and non-ionic polymeric surfactant

15:40-16:00 Emile Engel Composite hydrogels combining TEMPO oxidised

cellulose with an amino acid-based coordination polymer

16:00-17:00 Plenary Talk and Closing Remarks

Plenary:

The Life of a Small-Angle Neutron Scatterer

Dr Sarah Rogers ISIS Neutron and Muon Source, Didcot

Small-Angle Scattering (SAS) is a powerful technique for determining microstructure in the range of

tens to thousands of Angstroms. Small-Angle Neutron Scattering (SANS) is particularly useful when

studying multi-component systems, as is often the case in colloid science, by using appropriate

isotopic substitution within a sample [1].

In this talk the use of SAS throughout my career will be demonstrated in everything from the study of

water-in-CO2 microemulsions to the location of lipids in multi-lipid system.

The current status and future upgrade projects on the SANS Instruments at ISIS [2 - 5] will also be

discussed with the aim of showing the future direction of SANS at ISIS (and hopefully inspire new ISIS

proposals!).

References

[1] R.K. Heenan et al, J. Appl. Cryst. 30 (1997) 1140.

[2] www.isis.stfc.ac.uk/instruments/loq/

[3] www.isis.stfc.ac.uk/instruments/sans2d/

[4] www.isis.stfc.ac.uk/instruments/larmor/

[5] www.isis.stfc.ac.uk/instruments/zoom/

SESSION 1 Ultralow friction mediated by centipede copolymers under

confinement Nicholas Taylora, Beatrice N. Cattozb, Andrew D. Schwarzb, Peter J. Dowdingb, Brian Vincenta and

Wuge H. Briscoea

aUniversity of Bristol bInfineum UK Ltd

The extraordinarily effective biolubrication provided by the synovial fluid in joints, where the friction

coefficient μ≈10-3 at pressures up to 100 atm,1 has long been the envy of engineering applications.

Achieving similarly low friction in oil-based lubricants would lead to enormous economic and

environmental benefits from reducing wear, improving fuel economy and reducing CO2 emissions.

However, the ultralow friction seen in synovial joints, which arises from synergistic interactions

between many different biomolecules present in the synovial fluid, 2, 3 has proven to be very

challenging to replicate in a non-aqueous medium.

Here, we demonstrate the attainment of ultralow friction by a class of functionalised, statistical,

amphiphilic ‘centipede’ copolymers. Using the surface forces apparatus (SFA), we have measured the

normal and shear forces acting between polymer boundary layers under confinement in a point

tribocontact, across two mica surfaces in n-dodecane. Complemented by X-Ray Reflectivity (XRR) 4 and

adsorption isotherm measurements, we compare the interfacial structures formed by two different

deposition methods: 1) equilibrium physisorption from solution in a model oil, and 2) Langmuir-

Blodgett (LB) deposition.

Our shear measurements demonstrate very effective lubrication (μ ≈ 0.002), comparable to that found

in synovial joints, between polymer layers prepared via LB deposition. This is in stark contrast with the

higher friction (μ ≈ 0.05-0.1) observed between layers formed by equilibrium physisorption. These

results demonstrate unprecedented lubrication efficacy by statistical copolymers in oil-based media

and the dramatic effect of interfacial structure on nanotribological behaviour, which has possible

implications for future molecular design in oil-based lubrication.

Figure 1: (a) ‘Centipede’ copolymer architecture. (b) Friction (FS) vs. normal load (FN) plots from SFA

measurements in n-dodecane, for films prepared via physisorption (black) and Langmuir-Blodgett deposition

(red).

References

1. N. Y. Afoke, P. D. Byers and W. C. Hutton, Journal of Bone and Joint Surgery, 1987, 69B, 536-541.

2. J. Seror, L. Zhu, R. Goldberg, A. J. Day and J. Klein, Nature Communications, 2015, 6, 6497. 3. L. Zhu, J. Seror, A. J. Day, N. Kampf and J. Klein, Acta Biomaterialia, 2017, 59, 283-292. 4. W. H. Briscoe, F. Speranza, P. X. Li, O. Konovalov, L. Bouchenoire, J. van Stam, J. Klein, R. M.

J. Jacobs and R. K. Thomas, Soft Matter, 2012, 8, 5055-5068.

Dimensional and morphological control of perylene diimide-

based supramolecular polymers

Henry Symons, Charlie Jarrett-Wilkins, Ian Manners and Charl FJ Faul

University of Bristol

The dynamic nature of supramolecular polymers, arising from the non-covalent interactions which

comprise them, results in attractive properties including low melt viscosities, and the ability to form

self-healing materials. Recently, achieving control over the structures formed by supramolecular

polymers has received increasing attention.[1] The seeded-growth method has been used with great

success in controlling the length of these dynamic systems, however the formation of more complex

structures remains challenging.[2]

Perylene diimides (PDIs) are functional dye molecules possessing strong absorbance and fluorescence,

good photostability and n-type semiconductivity. In addition to their potential application in organic

photovoltaics, these characteristic optoelectronic properties, and their changes upon aggregation,

make PDIs ideal candidates for detailed self-assembly studies.[3] We recently demonstrated precise

length control over the self-assembled fibres of an amphiphilic PDI bearing hydrophilic oligo(ethylene

glycol) tethers by suppressing spontaneous aggregation.[4]

In this work we aim to further explore the possible architectures that may be attained with these

systems. In addition to fibre length control, width control over the structures is also demonstrated in

the formation of platelet morphologies. Supramolecular polymers formed from PDIs with thionated

cores are also demonstrated, along with progress towards the formation of supramolecular block

copolymers.

References

[1] L. Yang, Chem. Rev. 2015, 115, 7196–7239.

[2] R. D. Mukhopadhyay, Science, 2015, 349, 241–242.

[3] G. Echue, Chem. Eur. J. 2015, 21, 5118–5128.

[4] C. Jarrett-Wilkins, Chem. Eur. J. 2018, 24, 15556–15565.

A self-activated antimicrobial cellulose film producing

hydrogen peroxide via enzyme coupled reaction: a promising material for wound treatments

Davide Califano, Marco Kadowaki, Karen Edler, Davide Mattia and Janet Scott

The University of Bath

Bacterial antibiotic resistance is considered a threat for human health worldwide. In particular,

selection of multi-drug resistant microorganisms makes chronic wounds management very

challenging for healthcare systems. The use of enzymes as antimicrobial agents is extensively studied.

The presence of a cellulose binding module in enzymes could promote specific interaction towards

cellulose based supports. My research work is aiming to describe the use of immobilised enzymes in

regenerated cellulose films as antimicrobial machinery. More than one enzyme, immobilised into a

suitable polymeric support could work synergistically in sequential reactions producing antimicrobial

molecules, e.g. hydrogen peroxide or halogenated compounds. Moreover, using biodegradable

immobilisation support, it is possible to ensure sustainability and biocompatibility in patients. Enzyme

possessing cellulose binding module interact specifically and strongly with supporting materials used

in my research, avoiding leakage which could promote bacterial growth. In the last work I described

the potential use of cellobiose dehydrogenase from Myceliophthora thermophila (MtCDHA) and

cellobiohydrolase from Trichoderma reesei (TrCBHI) as coupled enzymatic antimicrobial machinery

immobilised in regenerated cellulos. Enzymes, singularly immobilised into regenerated cellulose films

(RCF) and stacked together, worked synergistically in sequential reaction producing H2O2. The

TrCBHI/MtCDHA/RCF system resulted to be activated by stacking TrCBHI/RCF and MtCDHA/RCF

together opening opportunities for the development of other modular antimicrobial enzymatic

systems.

Characterisation of surface morphology and nanomechanical

properties of synthetic fibres. From nanoscopic fibre structure to sensation of touch

Dajana Gubala, Wuge H. Briscoe

The University of Bristol

Understanding the relationship between textile fibres properties and manufacturing is essential for

their industrial applications. Here, we present a micro-/nanoscopic characterisation of seven synthetic

fibres having the application as personal care products. Since human tactile discrimination extends to

few nm [1], characterisation of fibres surface nanostructure and nanomechanical properties is of high

relevance. We have obtained fibres geometry, morphology, and nanomechanical properties using

optical microscopy (OM), scanning electron microscopy (SEM), atomic force microscopy (AFM). For

polyethylene/polyethylene terephthalate (PE/PET) single bicomponent fibres, PE sheath was found to

possess fibrillar microstructure – typical for drawn fibres [2], whereas for fibres entangled in

nonwoven fabrics, we observed a uniform, porous surface. Fibres porosity origins from a thermal

separation between the solvent and the polymer phases occurring after cooling down the

temperature of the polymer/solvent mixture [3, 4]. Adhesion force mapping allowed us to correlate

fibre nanomechanical properties with its topography with pores showing higher adhesion than the flat

surface. Furthermore, on polypropylene (PP) fibre surface treated with erucamide (13-cis-

docosenamide; the common slip additive used in polyolefin film processing [5]) we observed

numerous, overlapping multilayers with 4 nm bilayer thickness, attributed to the slip additive

migration onto fibre surface. Erucamide presence affected fibre adhesive properties, indicating its

great potential to provide lubrication. We discuss our observations in terms of fibres composition,

surfactant treatment, nonwoven manufacturing process and fibres potential to tailor tactile

properties. The future research can focus on fibres friction properties as well as interactions between

fibres coatings and human skin.

Figure: a) microfibrilar and b) porous PE

structure; c) height and d) adhesion AFM map of

PE porous structure.

References

[1] Skedung, L., et al., Scientific Reports, 2013. 3: p. 2617.

[2] Peterlin, A., Journal of Materials Science, 1971. 6(6): p. 490-508.

[3] Lloyd, D.R., K.E. Kinzer, and H.S. Tseng, Journal of Membrane Science, 1990. 52(3): p. 239-261.

[4] Dayal, P., et al., Macromolecules, 2007. 40(21): p. 7689-7694.

[5] Chen, J., et al.,. Journal of Vacuum Science & Technology 2007. 25.

3D-printed Power – Functional Polymers for Soft Robotics

Christian P Romero, Jonathan Rossiter, Charl F J Faul

The University of Bristol

Novel methods to fabricate bendable and stretchable energy storage devices with improved

performance for flexible and wearable electronics are of great current interest. Scalable

manufacturing procedures are crucial for practical application in the fabrication of complete

functional electronic devices. Here we report a scalable hybrid fabrication process of 3D

printing combined with laser engraving to construct highly flexible and stretchable

supercapacitors. CAD-designed supercapacitors were manufactured with a customized

commercial 3D-printer equipped with a 460 nm commercial laser.

In addition, we present our route to the development, formulation and preparation of the

main components required for a fully 3D-printed flexible and stretchable supercapacitor. A

range of functional 3D-printable inks were developed to enable printing of the current

collectors, electroactive electrode materials, the electrolytes, as well as the flexible and

stretchable housing. In addition to the development of such inks, we have combined printing

with laser-scribing of the functional inks. Specifically, high superficial capacitance is achieved

with conductive current collectors obtained by simple laser-scribing reduction of graphene

oxide (GO) flakes in a 3D-printed polyethylene oxide (PEO)/GO-based material. The resulting

reduced GO-based 3D micro structures are transferred onto a commercial UV-curable silicon

rubber to obtain flexible current collectors. The flexible conductive collectors were coated

with a 3D-printed PEO/polyaniline-based electroactive material. These component are

integrated with a polyvinyl alcohol/sulphuric acid-based gel electrolyte to obtain a flexible

and stretchable supercapacitor.

SESSION 2 Charge-driven interfacial gelation of cellulose nanofibrils

across the water/oil interface

Vincenzo Calabrese, Marcelo A. da Silva, Julien Schmitt, Kazi M. Zakir Hossain, Janet L. Scott, Karen J.

Edler

The University of Bath

In the recent decades, rod-like cellulose nanoparticles assembly across the water/oil (W/O) interface

has been broadly investigated in the context of Pickering emulsions due to the excellent performance

combined with the employment of a renewable and sustainable source. In this study we investigate

the spontaneous adsorption of oxidised cellulose nanofibrils (OCNF) across planar W/O interfaces

under conditions where bulk contributions are negligible, allowing exploration of the interfacial

phenomena alone. Spontaneous adsorption of the water-dispersible OCNF across the W/O interface

was induced employing an oppositely-charged oil-soluble surfactant. This approach relies on the use

of two immiscible liquids as scaffolds, delivering two oppositely-charged species and directing a

charge-driven complexation across the W/O interface. Interfacial rheology experiments showed that

upon complexation of OCNF and the oppositely charged polyelectrolyte, interfacial gels were

produced, and, different interfacial properties obtained modulating the ζ-potential of the OCNF (by

electrolyte addition). Spontaneous OCNF adsorption at the W/O interface occurred for particles with

ζ-potential more negative than -30 mV, resulting in the formation of interfacial gels; whilst for particles

with ζ-potential of ca. -30 mV, spontaneous adsorption occurred coupled with augmented interfibrillar

interactions, yielding stronger and tougher interfacial gels. Contrarily, charge neutralisation of OCNF

(ζ-potential values more positive than -30 mV) did not allow spontaneous adsorption of OCNF at the

W/O interface. In the case of favourable OCNF adsorption, the interfacial gel was found to embed oil-

rich droplets - a spontaneous emulsification process (Figure 1). The development of interfacial gels

has implications for capsule formation and tuning in O/W emulsions – systems where interfacial

rheology studies are extremely challenging, yet where tuneability is key to utility.

Figure 1: (Top) Interfacial gel formed across a macroscopic water droplet, (center) microscopy pictures

of the oil-rich droplets embedded into the interfacial gel, (bottom) Schematic representation of the

charge-driven assembly across the W/O interface.

Zipper polyelectrolyte brushes from interfacial coacervation

S. Ruscigno1, K. Braeckman2, E. Robles3, A. Brooker3, W. H. Briscoe1

1School of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom 2Procter & Gamble, Brussels Innovation Center, 1853, Brussels, Belgium 3Procter & Gamble, Newcastle Innovation Center, Newcastle Upon Tyne, NE12 9BZ, United Kingdom

Conjectured to be related to “the origin of life on Earth” by Oparin, coacervation refers to association

of oppositely charged macro-ions, an electrostatically-driven liquid-liquid phase separation process

that is extensively found in nature. Coacervation of polyelectrolytes, nanoparticles, and surfactants is

actively being exploited for the rational design of bio-inspired functional nanomaterials and new

interfacial structures in a wide range of applications such as biomedical adhesives, coatings,

microencapsulation technologies, gene delivery, anti-fouling, and as emulsion and foam stabilization.

We are exploring interfacial coacervation to design, fabricate, characterise and evaluate pH-

responsive zipper polyelectrolyte brushes, which can be replenished by switching the solution pH.

Such zipper brushes are formed by adsorbing an amphoteric block copolymer brush (ABC) to a surface-

anchored polyanionic di-block copolymer (PAD) at pH>~7. The complexation (or coacervation)

between the positively charged ABC and the negatively charged polymer block in PAD can be reversed

at pH<3 and pH>12, leading to the zipping-on and zipping-off of the ABC brush. Furthermore, the PAD

brush is prepared using the Langmuir-Blodgett method with controlled brush density, and

subsequently transferred to mica. The brush structure is characterised at the air-liquid, air-solid and

solid-liquid interfaces using X-ray reflectivity (XRR). Subsequently, the adsorption of the ABC brush on

the PAD brush is studied, varying the polymer molecular weight and architecture, and the pH

condition. The structure of such zipper brushes is studied using XRR (Figure 1a) and QCM-D (Figure

1b) to assess the adsorbed amount and the film viscoelastic properties at different pH.

Figure 1a: XRR curves for 1) PS-mica + PAD monolayer (blue), 2) PS-mica + PAD and adsorbed ABC at pH 7 (pink), and 3) PS-mica + PAD + ABC at pH 3 (yellow). Figure 1b: QCM-D data of frequency shift (blue) and dissipation shift (red) of a PS-coated quartz sensor during a conditioning period of PAD-coated PS-sensor (0), ABC adsorption at pH 7 (1), rinsing from ABC excess (2) and ABC desorption at pH 12 (3). Only three relevant harmonics are shown (n = 3, 5, 7) for clarity.

Self Assembly of Alpha-Synuclein Fibrils

Han Yin, Dr Adam Squires, Dr Jody Mason, Richard Meade, Dr Ben Eves and Eleonore Mason

The University of Bath

Parkinson’s disease is a progressive neurodegenerative disorder that is becoming increasingly

prevalent in the ageing population of today. The pathogenesis of Parkinson’s disease is linked to the

presence of Lewy bodies – clamps of misfolded alpha-synuclein proteins that induce the apoptosis of

neuron cells. Although the general pathways of alpha-synuclein aggregation have been explored, the

detailed interactions regarding each step of aggregation, from monomeric protein to fibrils and

propagation, have not been fully understood. Moreover, modelling primary nucleation has been time-

consuming and unreliable in the past. Recent studies of aggregation kinetics focus on seeded

aggregation, where mature fibrils are broken into seeds and loaded into a monomeric environment.

The advantage of such approach is increased reliability and a closer representation of the PB brain,

where the presence of seeds is highly likely. Here, we utilize the traditional method of ThT assay to

examine the kinetics of freeze-thawed alpha-synuclein seeds that we expressed, purified and

aggregated in-house using the methods adapted from The Mason Group. We found that the

purification technique is adequate in obtaining pure alpha-synuclein for fibril seeds formation and that

the kinetic data is similar to past literature (2nd order overall, K+ = nx103). We also found that

aggregation in sodium phosphate buffer is superior to PBS buffer due to more even distribution of the

fluorescence signal. Finally, the data suggest potential additional mechanisms for seeded aggregation,

which we hope to investigate further in future experiments.

Automating reflectometry reduction and analysis at Diamond

Light Source

Andrew R. McCluskey1,2, Tim Snow1,3, Jos F.K. Cooper4

1. Diamond Light Source

2. University of Bath

3. University of Bristol

4. ISIS Neutron and Muon Source

This presentation will focus on the ongoing work at Diamond Light Source to automate data reduction

and analysis at the I07 X-ray reflectometry (XRR) beamline. I07 focuses on the study of surfaces and

interfaces, and is the only synchrotron XRR beamline in the UK capable of probing liquid-gas interfaces,

since it has a horizontal sample geometry.

We present the work completed so far which has enabled a fully automated and reproducible process

for the reduction of experimental data from beamline specific parameters into the conventional

reflectivity versus momentum transfer. We will then introduce ongoing work to move towards the

automation of experimental analysis. This will cover the development of a “data analysis as a service”

framework at the beamline, the use of information theory for model comparison and investigations

into the application of machine learning to reflectometry analysis.

SESSION 3 Molecular Mechanisms in Hydrogen-Bonding Rich Non-

Aqueous Solvents

Lauren Matthews1,2, Robert Sochon 3, Andrew J. Johnson3, and Wuge H. Briscoe2

1 Bristol Centre for Functional Nanomaterials, University of Bristol, Bristol. 2 School of Chemistry,

University of Bristol, Bristol. 3 GlaxoSmithKline, St George’s Avenue, Weybridge, Surrey, KT13 0DE

Self-Assembly of surfactants, which has been well studied in aqueous and nonpolar systems, is not as

well understood in hydrogen-bonding rich non-aqueous solvents, such as glycerol. Understanding the

self-assembly mechanism in these hydrogen-bond rich solvents is important fundamentally and

industrially, where molecular organisation, complexation, and assembly of amphiphilic functional

additives play an important role. Further, product formulations make use of non-aqueous solvents

due to their desirable physical properties, such as high boiling points, low toxicity, and solvency for

organic molecules[1,2].

This work aims to study self-assembly of amphiphiles in non-aqueous solvents and to assess the

validity of models[3-5] designed for bulk and interfacial aqueous self-assembly. The air-liquid interface

was probed using tensiometry for SDS in a range of solvents. The critical micelle concentration (CMC)

increased in the following trend: water (8.1 mM), glycerol (11.7 mM), and ethylene glycol (> 300 mM),

suggesting that the solvophobic effect is strongest in water. Surprisingly, a gel-like mesophase was

observed for SDS in glycerol (2 wt %) and ethylene glycol (10 wt %). Polarised optical microscopy

(POM) showed the presence of large fibre-like aggregates with macroscopic dimensions, larger than

that of an SDS micelle. Rheology of the phase showed an elastic-dominated material, with an elastic

modulus in the order of 104 Pa. Small-angle neutron scattering (SANS) of this phase showed a lamellar

phase at 25oC, that reversibly transitioned into a micellar phase upon heating. Such unprecedented

structural characterization facilitates a discussion of the effect of the hydrogen-bonding properties of

the solvents in mediating self-assembly.

Figure 1 (A) POM image of 4 wt % SDS in glycerol, taken at 40 x magnification, with a 530 nm first

order waveplate. (B) Frequency sweep rheology data for 4 wt % SDS in glycerol, with phase angle

(green), elastic (G’, red), and viscous (G”, blue) moduli. (C) SANS data for 4 wt % SDS in glycerol

showing the reversible phase transition with temperature

References

[1] H. C. Hailes, Org. Process Res. Dev., 11 2007, 114-120.

[2] Y. L. Gu and F. Jerome, Green Chem., 12 2010, 1127-1138.

[3] C. Tanford, Science, 200 1978, 1012-1018.

[4] J. N. Israelachvili et al., J. Chem. Soc. Faraday T2, 72 1976, 1525-1568.

[5] J. N. Israelachvili, Colloid Surface A, 91 1994, 1-8.

Reversible temperature-controlled gelation in mixtures of

pNIPAM microgels and non-ionic polymeric surfactant

S L Fussell, K Bayliss, M A Faers, C P Royall, J S van Duijneveldt

The University of Bristol

Understanding colloidal gelation is a long-standing challenge in soft matter. A variety of mechanisms

have been postulated [1], and often the mechanism of spinodal decomposition is found in mixtures of

colloids and other species, including polymers [2]. However, other mechanisms are also possible, for

example, gelation due to polymer bridging [3]. Here we investigate the temperature-dependent

gelation of mixtures of poly(N-isopropylacrylamide) (pNIPAM) microgels and a non-ionic polymeric

surfactant.

pNIPAM is a temperature-responsive polymer that can be synthesised to form cross-linked microgels.

As the temperature response is close to physiological conditions, pNIPAM research often focuses on

its potential for biomedical applications [4]. We discovered that at elevated temperatures, mixtures

of pNIPAM and polymeric surfactant undergo a reversible transition from transparent liquid to solid

gel [5]. Our investigations reveal that the gelation results from the association of the two species in

solution, rather than the common gelation regime of depletion, where non-adsorbing polymer causes

colloidal aggregation. This association, at low concentrations, is highlighted by an increase in the

hydrodynamic radius of the microgels in the presence of surfactant at elevated temperatures. At high

concentrations, the associative mechanism results in network formation, where confocal microscopy

of the fluorescently labelled polymers showed that both species are present in the gel network.

We use synthetic techniques to alter the architecture of the microgels to gain greater insight into the

gelation mechanism. It was found that for particles with a uniform cross-link distribution the gelation

mechanism is hindered, and the pNIPAM particles remain stable individual particles in solution. This

result adds further weight to the associative gelation mechanism, and highlights that the diffuse

corona of the microgels plays a role in the association that drives gelation. The gel network structures

that result have the potential for use in tissue engineering applications.

Confocal microscopy images of 3 wt% pNIPAM and 3 wt% surfactant, fluorescent signal from

fluorescein labelled microgels (left), fluorescent signal from Nile red labelled polymeric surfactant

(centre) and fluorescent signal from both components (right). All images are taken at 50 oC, scale bar

10 µm.

References

[1] E. Zaccarelli, J. Phys.: Condens. Matter, 16 2007 323101.

[2] C. P. Royall et al., Nature Materials, 7 2008 556.

[3] Y. Yasufumi, Langmuir, 6 1990 114.

[4] Y. Guan et al, 2011, Soft Matter, 7 2011 6375.

[5] K. Bayliss, University of Bristol, PhD thesis 2014.

Composite hydrogels combining TEMPO oxidised cellulose

with an amino acid-based coordination polymer

Emile R. Engel,† Vincenzo Calabrese,† Karen J. Edler and Janet L. Scott

†These authors contributed equally.

The University of Bath

Biopolymer-based hydrogels have received considerable attention as promising materials for tissue

engineering.1 Cellulose-based hydrogels, specifically, have also been explored for applications in drug

delivery, agriculture and personal hygiene products.2 Promising composite materials can be prepared

by combining cellulose as a structural component and coordination polymers (CPs), including metal-

organic frameworks,3 as versatile functional components.

We present one-step ambient temperature fabrication of cellulose-based hydrogels with long term

stability, of spheroidal structure, where a CP is prepared in situ and remains embedded within the

hydrogel matrix. We employed an alkaline dispersion of TEMPO-oxidised cellulose nanofibrils (OCNF),

containing silica nanoparticles (SiNP) as rheological modifier and an amino acid ligand. When droplets

of the dispersion are extruded into aqueous Cu(NO3)2 solution, gelation occurs leading to spheroid-

shaped hydrogels, while the ligand and Cu2+ self-assemble to generate an anisotropic distribution of

1-D chiral CP crystallites within the spheroids. The degree of enantiomeric excess of the amino acid

ligand substantially affects the self-assembly rate of the chiral CP. By varying the ligand enantiomeric

excess we investigated the effect of CP self-assembly rate on the distribution and density of CP

crystallites within the hydrogel structures. In principle, the procedure presented here can be adapted

to incorporate a variety of potential CPs provided that factors such as viscosity of the matrix, CP self-

assembly rate and size of the hydrogel structures are accounted for.

References

[1] S. Van Vlierberghe, P. Dubruel and E. Schacht, Biomacromolecules, 2011, 12, 1387–1408.

[2] C. Chang and L. Zhang, Carbohydr. Polym., 2011, 84, 40–53.

[3] K. J. Lee, J. H. Lee, S. Jeoung and H. R. Moon, Acc.Chem.Res., 2017, 50, 2684−2692.

Poster Session

Presenter Title

Esther Townsend Influence of a pH-responsive electroactive amphiphile on the formation of lipid cubic phases

Holly Stockdale The Role of Cardiolipin in the Self-Assembly of Bacterial Membrane Mimics

Andrew Hambly Oxidation of Carotene by Acid Treated Montmorillonite Particles

Michael Stevens The impact of molecular architecture of block copolymers on lubrication efficacy in non-aqueous media

Alexandra Barnes Tuning of Catalytic Sites in Pt/TiO2 Catalysts for Chemoselective Hydrogenation of 3-nitrostyrene

Sajad Kiani Hindering Asphaltene Deposition under Low and High Brine Conditions using a Low Surface Energy Anionic Surfactant During Enhanced Oil Recovery (EOR)

Matthew Slade Improving the Thermal Stability of Bacteriophages

Wafaa Al-Shatty Various functionalized nanoparticles for enhanced oil recovery applications

George Neville Effect of Polymer End Group on the Formation of Styrene-Maleic Acid Lipid Particles (SMALPs).

THANK YOU FOR ATTENDING!

The Organising Committee:

Saffron Bryant (University of Bath)

Zakir Hossain (University of Bath)

Han Yin (University of Bath)

Gina Moody (University of Bristol)

Nimai Mehta (Cardiff University)