biodegradable polymers - advanced topic in polymers synthesis
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Department of Chemistry Polymer Science Freie Universität Berlin
Biodegradable polymers Environment friendly materials
Cristiane Henschel
Advanced Topics in Polymer Synthesis
Polymer Science Master Program
Freie Universität Berlin
November 13th, 2013
Department of Chemistry Polymer Science Freie Universität Berlin
Table of Contents
• Introduction
• Biodegradability
• Biodegradable Groups
• PLA: Synthesis and Degradation
• Oxo-biodegradability
• Applications
• Standards
• Life cycle assessments (LCA)
• Major limitations
References
(listed at the end)
Department of Chemistry Polymer Science Freie Universität Berlin
PET
PVC
POM
PC
...
PEG
PBAT
PCL
PBS
...
PLA
PGA
PHA
TPS
...
PE
PP
PA
PET
...
Introduction
Biodegradable
Fossil resources
Biodegradable
Renewable resources
Not biodegradable
Fossil resources
Not Biodegradable
Renewable resources
PE
PP
PS
PA
Department of Chemistry Polymer Science Freie Universität Berlin
Introduction
• Biodegradable:
– CO2 / CH4 / H20 / inorganic compounds / biomass
– Available disposal conditions
– Enzymatic action of microorganisms
– Can be measured
• Compostable:
– Biological processes during
– Composting conditions
– Rate consistent with other compostable materials
– CO2 / H20 / inorganic compounds / biomass
– No visible, distinguishable or toxic residue
Department of Chemistry Polymer Science Freie Universität Berlin
Biodegradability
• First Step: fragmentation
• Second Step: biodegradation
Department of Chemistry Polymer Science Freie Universität Berlin
Biodegradable Groups
• Polyesters
• Polyamides
• Polyurethanes
• Polyureas
• Polyanhydrides
• Poly(ester amides)
• Poly(orthoesters)
• Poly(phosphoesters)
• Vinyl polymers with oxidizable functional groups
urethane
ester amide
polyurea polyanhydride
phosphoester ortoester PVA
Department of Chemistry Polymer Science Freie Universität Berlin
PLA Synthesis
Anhydrides
Epoxides
Isocyanates
Low pressure and ~ 130°C
Aprotic solvent + catalyst
Only method for highly
pure PLA with high Mw
Solution, Bulk, Melt
or Suspension
Anionic
Cationic
Coordination
Department of Chemistry Polymer Science Freie Universität Berlin
PLA Degradation
Bioabsorbable
Department of Chemistry Polymer Science Freie Universität Berlin
Oxo-Biodegradability
• Controversial biodegradation methods
• Additives added to conventional
polymers to facilitate their biodegradation
• Based on metal combinations (e.g.: Mn2+ / Mn3+)
(also cobalt, magnesium, iron, zinc etc)
• Degradation by free radical
• Blends of biodegradable and durable polymers (PE + starch)
Department of Chemistry Polymer Science Freie Universität Berlin
Applications
• Agriculture
– Mulch films
– Controlled release of chemicals
• Disposables
– Fast-food tableware
– Food wrappers and containers
• Textiles
– Industrial wipes
– Filters
– Hygene products
Department of Chemistry Polymer Science Freie Universität Berlin
Applications
• Medicine
– Controlled drug delivery
– Implants and sutures
– Vascular grafts
– Artificial skin and scaffolds
• Active packaging
– Moisture absorption
– CO2 and C2H4 generation
– Controlled diffusion of
antimicrobial agents
Department of Chemistry Polymer Science Freie Universität Berlin
Standards
• ASTM D6868-11 Compostability of Polymers as Coatings
• ASTM D6400-12 Compostability of Plastic products in general
• ISO 17088:2008 Compostability of Plastics
• EN 13432:2000 Compostability of Plastics on packaging applications
• EN 14995:2006 Compostability of Plastics on non-packaging applications
• Chemical test (heavy metals content)
• 90% of conversion into CO2 within 6 months
• No negative influence on the composting process
• No negative effect on plants growth
Department of Chemistry Polymer Science Freie Universität Berlin
Life Cycle Assessments
Contribution to climate change
Smog creation
Eutrophication
Acidification
Human and ecosystem toxicity
Emissions
Waste
Resources
Department of Chemistry Polymer Science Freie Universität Berlin
Major Limitations
• Inferior properties (strength, dimensional stability etc)
• High cost
• Technically difficulties to process
– Narrow “processing window”
– Low thermal stability
– Highly hydrophilic
– Difficult reprocessing
– Adhesion to machinery
Department of Chemistry Polymer Science Freie Universität Berlin
References
1. Accountability is key - Environmental Communications Guide for Bioplastics. European Bioplastics : Berlin, 2012.
2. Luckachan, G. E.; Pillai, C., Biodegradable polymers-a review on recent trends and emerging perspectives.
Journal of Polymers and the Environment 2011, 19 (3), 637-676.
3. Tang, X.; Kumar, P.; Alavi, S.; Sandeep, K., Recent advances in biopolymers and biopolymer-based
nanocomposites for food packaging materials. Critical reviews in food science and nutrition 2012, 52 (5), 426-
442.
4. Vroman, I.; Tighzert, L., Biodegradable polymers. Materials 2009, 2 (2), 307-344.
5. Belgacem, M. N.; Gandini, A., Monomers, Polymers and Composites from Renewable Resources. Elsevier
Science: 2011.
6. Avérous, L.; Pollet, E., Environmental Silicate Nano-biocomposites. Springer: 2012.
7. Okada, M., Chemical syntheses of biodegradable polymers. Progress in Polymer Science 2002, 27 (1), 87-133.
8. Babu, N. R.; Anitha, N.; Rani, R. H. K., Recent Trends in Biodegradable Products from Biopolymers. Biopolymers
2010, 2, 4.
9. Imran, M.; Revol-Junelles, A.-M.; Martyn, A.; Tehrany, E. A.; Jacquot, M.; Linder, M.; Desobry, S., Active food
packaging evolution: transformation from micro-to nanotechnology. Critical reviews in food science and nutrition
2010, 50 (9), 799-821.
10. Tian, H.; Tang, Z.; Zhuang, X.; Chen, X.; Jing, X., Biodegradable synthetic polymers: Preparation,
functionalization and biomedical application. Progress in polymer science 2012, 37 (2), 237-280.
11. Hottle, T. A.; Bilec, M. M.; Landis, A. E., Sustainability assessments of bio-based polymers. Polymer Degradation
and Stability 2013, 98 (9), 1898-1907.
12. Yates, M. R.; Barlow, C. Y., Life cycle assessments of biodegradable, commercial biopolymers—A critical review.
Resources, Conservation and Recycling 2013, 78, 54-66.
Department of Chemistry Polymer Science Freie Universität Berlin
Questions?
Bioegradable Polymers Evironment Friendly Materials Cristiane Henschel Advanced Topics in Polymer Synthesis Polymer Science Master Program Freie Universität Berlin November 13th, 2013
Thank you for your attention!
Department of Chemistry Polymer Science Freie Universität Berlin
Extras
Bioegradable Polymers
Evironment Friendly Materials
Cristiane Henschel
Advanced Topics in Polymer Synthesis
Polymer Science Master Program
Freie Universität Berlin
November 13th, 2013
Department of Chemistry Polymer Science Freie Universität Berlin
Biodegradable Polymers
• Synthetic
– Poly(ε-caprolactone) - PCL
– Poly(glycolic acid) – PGA
– Poly(lactic acid) - PLA
– Polyhydroxyalkanoates – PHA’s
– Thermoplastic Starch – TPS
– Poly(ethylene glycol) – PEG
– Poly(dioxanone) – PDO
• Natural
– Polysaccharides • Starch
• Chitin and Chitosan
• Pectin
– Proteins • Gelatin
• Casein
PGA
PCL
PDO
PEG
Department of Chemistry Polymer Science Freie Universität Berlin
Biodegradable Groups
R1 C X
O
R2
OH2
R1 C OH
O
+ HX R2Where X= O, N, S
R1 C O
O
R2
Ester
R1 C NH
O
R2
Amide
R1 C S
O
R2
Thioester
X C X'
O
R2R1
OH2
+ HX' R2X C OH
O
R1
Where
X and X’=
O, N, S O C O
O
R2R1 NH C O
O
R2R1 NH C NH
O
R2R1
Carbonate Urethane Urea
Department of Chemistry Polymer Science Freie Universität Berlin
Biodegradable Groups
R1 C X
O
C
O
R2
OH2
+R1 C OH
O
HX C
O
R2
R1 C NH
O
C
O
R2 R1 C O
O
C
O
R2
Imide Anhydride
Where X and X’= O, N, S
R C O C R'
H H
H H
OH2
R C OH
H
H
R' C OH
H
H
+
RO P OR'
O
OR''
OH P OH
O
OR''
OH2
+ +R OH OH R'
Department of Chemistry Polymer Science Freie Universität Berlin
Factors Influence the
Degradation Behavior
Chemical Structure and Chemical Composition
Distribution of Repeat Units in Multimers
Molecular Weight
Polydispersity
Presence of Low Mw Compounds (monomer, oligomers, solvents, plasticizers, etc)
Presence of Ionic Groups
Presence of Chain Defects
Presence of Unexpected Units
Configurational Structure
Morphology (crystallinity, presence of microstructure, orientation and residue stress)
Processing methods & Conditions
Method of Sterilization
Annealing
Storage History
Site of Implantation
Absorbed Compounds
Physiochemical Factors (shape, size)
Mechanism of Hydrolysis (enzymes vs water)
Department of Chemistry Polymer Science Freie Universität Berlin
Poly(vinyl alcohol) - PVA
“Among the vinyl polymers produced industrially, PVA
is the only one known to be mineralized by
microorganism. PVA ia water soluble and biodegradable
and hence, used to make water soluble and
biodegradable carriers, which may be useful in the
manufacture of delivery systems for chemicals such as
fertilizers, pesticides and herbicides.
PVA is completely degraded and utilized by bacterial
strain, Pseudomonas O-3, as a sole source of carbon and
energy.”
Premraj, R.; Mukesh, D.; Biodegradation of Polymers.
Indian Journal of Biotechnology, 2005, 4(2), 186-193.
Department of Chemistry Polymer Science Freie Universität Berlin
Polyamides
“Polyamides contain the same amide bound as in
polypeptides. Nevertheless polyamides have a high
crystallinity and strong chains interactions so that the rate of
biodegradation is lower than that of polypeptides. Enzymes
and microorganisms can degrade low molecular weight
oligomers. Biodegradation could be increased by the
introduction of various side groups as benzyl, hydroxyl and
methyl groups, through copolymerization for instance.”
Vroman, I.; Tighzert, L., Biodegradable polymers. Materials 2009, 2 (2), 307-344.
Department of Chemistry Polymer Science Freie Universität Berlin
Poly(lactic acid) - PLA
• L-lactide (natural form - obtained by fermentation of carbohydrates)
– Crystallinity about 37%
– Tg around 53°C
• D-L-lactide
– Amorphous
– Tg around 55°C
Department of Chemistry Polymer Science Freie Universität Berlin
PLA ROP by
Coordination Insertion
Department of Chemistry Polymer Science Freie Universität Berlin
PLA Cationic Polymerization
Department of Chemistry Polymer Science Freie Universität Berlin
PLA Anionic Polymerization
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