biodegradable polymers - advanced topic in polymers synthesis

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


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)


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


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


Biodegradability

• First Step: fragmentation

• Second Step: biodegradation


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


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


PLA Degradation

Bioabsorbable


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)


Applications

• Agriculture

– Mulch films

– Controlled release of chemicals

• Disposables

– Fast-food tableware

– Food wrappers and containers

• Textiles

– Industrial wipes

– Filters

– Hygene products


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


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


Life Cycle Assessments

Contribution to climate change

Smog creation

Eutrophication

Acidification

Human and ecosystem toxicity

Emissions

Waste

Resources


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


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.


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!


Extras

Bioegradable Polymers

Evironment Friendly Materials

Cristiane Henschel

Advanced Topics in Polymer Synthesis

Polymer Science Master Program

Freie Universität Berlin

November 13th, 2013


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



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



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'


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)


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.


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.


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


PLA ROP by

Coordination Insertion


PLA Cationic Polymerization


PLA Anionic Polymerization

biodegradable polymers - advanced topic in polymers synthesis

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