The Journey of Poly(lactic acid): From Commodities to Special Applications Saara Inkinen, Dr.Sc. (Tech.) [email protected]Senior Researcher, Laboratory of Polymer Technology, Åbo Akademi University Technology Transfer Project Manager, Technology Transfer Office, Åbo Akademi University FUNMAT Centre of Excellence SAB meeting, Helsinki, 14. August 2013
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The Journey of Poly(lactic acid): From Commodities to Special Applications · · 2015-05-10From Commodities to Special Applications Saara Inkinen, Dr.Sc. (Tech.) ... Saara Inkinen,
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Senior Researcher, Laboratory of Polymer Technology, Åbo Akademi University
Technology Transfer Project Manager, Technology Transfer Office, Åbo Akademi University
FUNMAT Centre of Excellence
SAB meeting, Helsinki, 14. August 2013
Carbohydrates from plants
Lactic Acid
Poly(lactic acid) Lactic acid
and LA-based oligomers
Carbon dioxide and
water PLA
and the
Natural
Carbon Cycle
Fermentation
Polymerization ROP or step-growth
polymerization
Hydrolysis
Microbes
Photosynthesis
of plants
+ H2O
CO2 + H2O
• At the moment raw material needs do not compete with food production (Natureworks)
• In the future, if production increases, alternative sources from wastes and side-products should be
considered
Aliphatic polyester
Global trends in the use of PLA: • Production volumes of PLA continuously
increasing
• Growing Markets
• Numerous new application areas, both
biomedical and technical
• Further research needed especially for:
• Non-commodity applications e.g.
electronics
• Tailoring the hydrolytic and thermal
degradation rate
• Predicting life-span in long-term use
How has the LPT as part of FUNMAT contributed to this development?
Recent PLA research at LPT is related to: • Renewable, degradable adhesives
• Electronic applications
• Medical applications
• PLA modification possibilities
• Renewable coatings for paper and paperboard
• Degradation and stability studies, LCA
Highlights from Doctoral Thesis and
Other PLA Related Research
Dr. Saara Inkinen (Dissertation held Jan 2011)
Lactic Acid-Based Copolymers Having Different Molecular Architectures - Synthesis
Method: Step-growth
polymerization in melt
Benefits:
• Simple one step method
• potentially cheaper than
ROP
• Easy use of comonomers
Challenges:
• long polymerization time
• low Mw
• Repeatability
The synthesized polymers are suitable for e.g. hot melt adhesives,
stereocomplexes, and applications in which a high Tg is required.
Source: Saara Inkinen, Doctoral Thesis: Structural Modification of Poly(lactic acid) by Step-Growth
Polymerization and Stereocomplexation
Thermal Stability of PLA Copolymers Having Different Molecular Architectures
60 min isothermal heating at different
temperatures.
Molecular shape: linear linear branched linear branched Polymer type: LA homo- COOH-terminated OH-terminated polymer
Saara Inkinen, Geoffrey A. Nobes, Anders Södergård, Telechelic Poly(L-lactic acid) for Dilactide Production and Prepolymer Applications, 2011,
Journal of Applied Polymer Science, 119, 2602-2610.
De
po
lym
eri
za
tio
n R
ate
(m
g/m
in)
60 min isothermal heating at different
temperatures.
Molecular shape: linear linear branched linear branched Polymer type: LA homo- COOH-terminated OH-terminated polymer
Conclusions:
The structure and chain-end termination of low Mw PLA affects its tendency for
depolymerization and racemization, important for e.g. lactide production
Hydroxyl-terminated PLA depolymerizes quicker and more completely at elevated
temperatures and undergoes more racemization during polymerization
Saara Inkinen, Geoffrey A. Nobes, Anders Södergård, Telechelic Poly(L-lactic acid) for Dilactide Production and Prepolymer Applications, 2011,
Journal of Applied Polymer Science, 119, 2602-2610.
Thermal Stability of PLA Copolymers Having Different Molecular Architectures
De
po
lym
eri
za
tio
n R
ate
(m
g/m
in)
Copolymers of Lactic Acid and Isosorbide Increasing the Tg of PLA
Conclusions: The glass transition temperature (Tg) of PLA can be increased significantly
using isosorbide and a polyfunctional comonomer in combination with lactic acid.
• The Tg and the crosslinking density can be readily adjusted by varying the comonomer ratio and the
reaction conditions
• The polymer can be used at higher temperatures than conventional PLA without deformation
Saara Inkinen, Mikael Stolt, and Anders Södergård, Readily Controllable Step-Growth Polymerization Method for Poly(lactic acid) Copolymers Having a
High Glass Transition Temperature, Biomacromolecules, 2010, 11, 1196–1201.
Polymer type Tg (°C)
PLA having a high molecular weight (ROP) 60 - 65
PLA having a low molecular weight (step-growth
polymerization) 40 or lower
Copolymers of lactic acid, isosorbide and 1,2,3,4-
butanetetracarboxylic acid 80
Copolymers of lactic acid, isosorbide and 1,2,3,4,5,6-
cyclohexanehexacarboxylic acid 86
Isosorbide
PLA Stereocomplexes
Made by blending of PLLA and PDLA (melt, solvent casting, reactive
extrusion)
Stereocomplex (γ) crystals are formed at a 1:1 PDLA/PLLA ratio
Compared to PLA homopolymers, PLA stereocomplexes have
A higher melting point (up to 240
C)
Higher thermal stability and resistance to deformation
Higher hydrolytic stability
Better resistance to solvents
Stereocomplex crystals are not soluble even in good solvents for
conventional PLA
Better mechanical performance
These differences derive from the very strong physical interaction between
the L-lactoyl and D-lactoyl sequences in the crystal structure
PLA Stereocomplexes Stereocomplexes were prepared by blending of
1. linear and branched lactic acid-based PDLA that was prepared by step-growth polymerization or ROP and
2. PLA having a high molecular weight (prepared by ROP).
The melting point and enthalpy of the stereocomplexes was dependent on the molecular structure and especially the molecular weight of the PDLA component.
Melting point Melting Enthalpy Saara Inkinen, Mikael Stolt, Anders Södergård, Effect of blending ratio and oligomer structure on the thermal transitions of stereocomplexes
consisting of a D-lactic acid oligomer and poly(L-lactide), Polymers for Advanced Technologies, 22, 12, 1658–1664, 2011
Hydrolytic Degradation of PLA Stereocomplexes
• Stereocomplexes having a high molecular weight were exposed to aqueous environments (water or buffer)
• As compared to PLA homopolymer, the stereocomplexes had: • slower hydrolytic degradation rates • a more acidic degradation pattern • shorter degradation products due to the short tie chains between the crystals.
PLLA homopolymer PLLA/PDLA stereocomplex
ESI-MS (Electrospray ionization-mass spectrometry) –spectra after a 13 weeks degradation period in water at 60
C:
Sofia Regnell Andersson, Minna Hakkarainen, Saara Inkinen, Anders Södergård and Ann-Christine Albertsson, Polylactide Stereocomplexation Leads to
Higher Hydrolytic Stability but More Acidic Hydrolysis Product Pattern, Biomacromolecules, 2010, 11 (4), 1067–1073.
Customizing the Hydrolytic Degradation Rate of
Stereocomplex PLA through Different PDLA Architectures
Factors Studied: temperature, degradation time, and
amount and type of D-LA oligomer
Method: fractional factorial experimental design.
Conclusion:
• The degree of stereocomplexation and degradation
rate can be customized by changing the architecture
and end-groups of the D-LA oligomers.
Analysis methods: • SEM, ESI-MS, DSC, Mass
Loss, pH
Sofia Regnell Andersson, Minna Hakkarainen, Saara Inkinen, Anders Södergård, and Ann-Christine Albertsson, Customizing the Hydrolytic
Degradation Rate of Stereocomplex PLA through Different PDLA Architectures, Biomacromolecules, 2012, 13 (4), pp 1212–1222
Poly(lactic acid) Research at LPT, ÅAU
Recent Highlights
Recent Industrial Collaboration Related to Biopolymers and PLA
Kiilto Oy
Biodegradable Hot Melt Adhesives Prof. Carl-Eric Wilén
Dr. Saara Inkinen
M.Sc. Chen Tan
Novel Biopolymer
Coatings Assoc. Prof. Ari Rosling & group
M.Sc. Mohammad Khajeheian
M.Sc. Worker Ella Lindström
Bone and cartilage regeneration Doctoral student Peter Uppstu
Assoc. Prof. Ari Rosling & group
Dr. Saara Inkinen
Recent Research Related to Biopolymers and PLA
Rheological Modification of
Biopolymers by Radical
Generators Prof. Carl-Eric Wilén
M.Sc. Teija Tirri
Dr. Saara Inkinen
Ion Modulated Transistors on Paper Wide collaboration within FUNMAT,
including but not limited to:
Prof. Ronal Österbacka (Physics)
M.Sc. Fredrik Pettersson (Physics)
Dr. Tommi Remonen
Prof. Carl-Eric Wilén
Dr. Saara Inkinen
M.Sc. Marco Mennillo (starting Sep. 2013)
Other PLA Related Publications from the
FUNMAT CoE period
Review
• Saara Inkinen, Minna Hakkarainen, Ann-Christine Albertsson,
Anders Södergård, Review: From Lactic Acid to Poly(lactic
acid) (PLA): Characterization and Analysis of PLA and Its