Biodegradation of polymers group 2

Brief introduction regarding polymers

1. BIODEGRADATION OF POLYMERS POLYMERS AND ENVIRONMENT KEJ 4604 GROUP 2 NAME : MUHAMMAD HELMI BIN SAPERI (UK29519) : MOHD SYUKRI BIN ABDULLAH (UK29529) LECTURER : ASSOCIATE PROF DR MOHAMAD AWANG DATE : 22 MARCH 2016 SEMESTER : II 2015/2016

2. APPLICATION MECHANISM INTRODUCTION CLASSIFICATION BIODGRADABLE POLYMERS TALK LAYOUT FACTORS

3. INTRODUCTION Polymer is derivation of ancient Greek word ‘ Polus ’ which means many, much and ‘ Meros ’ means parts. Refers to molecule whose structure is composed of multiple repeating units In general, polymer is a large molecule (macromolecule) composed of many repeating subunits (monomers) which linked via various ways to give linear, branched and cross linked polymer etc.

4. Examples of monomers & Polymers

5. What do we mean by ‘biodegradable polymer’ ? Based on Europian Union norm EN13432 defines as: “one possessing biodegradability (i.e. converted into carbon dioxide under microbial action‟), disintegrability (i.e. fragmentation and loss of visibility in the final compost), and an absence of negative effects in the final compost (e.g. a low level of heavy metals).‟

6. 140 million tonnes of synthetic polymers produced each year In Western Europe, 7.4% of MSW are plastics which classified as 65% polyethylene/polypropylene, 15% polystyrene , 10% PVC , 5% polyethylene terephthalate and others Major problem in wastewater INTRODUCTION – Cont’

7. WHAT TO DO

8. Combustion?  Discharges of toxic compounds (e.g. Dioxin) Landfill? (dry & anaerobic) Biodegradable polymer will not degrade as biodegradation process mediated by microorganism/enzymes and require water and oxygen (aerobic condition)

9. Does not decompose Inert and won’t react with what stored in them Durable and won’t easily decay PLASTICS

10. Since they do not decompose, the answer is to recycle the plastics, so they can be remade into something else. Here we see a bunch of CDs getting recycled

11. WHY POLYMERS IS POPULAR?

12. Inexpensive and easy to fabricate Light and strong Abundant and versatile

13. APPLICATIONS LDPE HDPE PE PVC

14. Natural Polymer : from nature (plant and animals) a) Collagen b) Albumin c) Dextran d) Gelatin Synthetic Polymer : man made polymers a) Polyethylene (HDPE, LDPE, PET) b) Polyvinylchloride (PVC) c) Polypropylene (PP) d) Polystyrene CLASSIFICATION

15. Natural Polymers Polymers Details Collagen found in mammals and provider of strength to tissues Use for biomedical applications such as surgery, cosmetics and drug delivery Poor dimensional stability and mechanical strength Albumin Major plasma protein component Used for designing particulate drug delivery system like insulin and Sulphadiazene Used in chemotheraphy in order to achieve high local drug concentration for longer time Dextran Complex branched polysaccharide made of many glucose molecules joined into chains of varying lengths Used for colonic delivery of drug in the form of gels Gelatin Mixtures of peptides and proteins produced by partial hydrolysis of collagen and extraction of boiled bones, connective tissues and organs Used as coating materials and oral controlled delivery of drugs

16. Synthetic Polymers

17. Synthetic or Natural Biodegradable Polymers Why Do We Prefer Synthetic Ones? Tailor-able properties Predictable lot-to-lot uniformity Free from concerns of immunogenicity Reliable source of raw materials

18. FACTORS AFFECTING BIODEGRADATION OF POLYMERS Morphological factors Shape & size Variation of diffusion coefficient and mechanical stresses Chemical factors Chemical structure & composition Presence of ionic group and configuration structure Molecular weight and pressure of low molecular weight compounds Physical factors Processing condition Sterilization process

19. Biodegradable Polymers Classification

20. Variety of available degradable polymers is limited due to stringent requirements – biocompatibility – free from degradation related toxic products (e.g. monomers, stabilizers, polymerization initiators, emulsifiers) • Few approved by FDA PLA, PLGA are used routinely

21. Polyesters Most degradable polymers are polyesters ester is a covalent bond with polar nature, more reactive can be broken down by hydrolysis the C-O bond breaks ESTER BOND

22. Ester production

23. Poly(glycolic acid) (PLGA) & Poly(lactic acid) (PLA) Poly( caprolactone ) (PCL) Most widely used biodegradable polymer PGA is the simplest aliphatic polyester highly crystalline, high melting point, low solubility PLA is more hydrophobic than PGA hydrophobicity of PLA limits water uptake of thin films to about 2% and reduces the rate of hydrolysis compared with PGA D,L-PLA used as drug delivery due to it is an amorphous polymer L-PLA used in mechanical applications ( orthopaedic devices) due to its semicrystalline characteristics PLGA with different ratios used for drug delivery with different degradation rate semi-crystalline polymer slower degradation rate than PLA remains active as long as a year as a drug delivery agent Capronor ®, implantable biodegradable contraceptive implanted under skin dissolve in the body and does not require removal degradation of the poly( epsilon - caprolactone ) matrix occurs through bulk hydrolysis of ester linkages , which is autocatalyzed by the carboxylic acid end groups of the polymer, eventually forming carbon dioxide and water , which are absorbed by the body

24. Poly(amides) contain a peptide (or amide) link can be broken down by hydrolysis the C-N bond breaks can be spun into fibres for strength AMIDE BOND

25. Poly(anhydrides) highly reactive and hydrolytically unstable degrade by surface degradation without the need for catalysts aliphatic (CH2 in backbone and side chains) poly(anhydrides) degrade within days aromatic (benzene ring as the side chain) poly(anhydrides) degrade over several years aliphatic-aromatic copolymers can be used to tailor degradation rate excellent biocompatibility & used in drug delivery

26. Poly( orthoesters ) formulated so that degradation occurs by surface erosion drug release at a constant rate degradation rate adjusted by acidic and basic excipients (acidic excipients increasing degradation rate)

27. Poly(amino acids) poly-L- lycine , polyglutamic acid Amino acid side-chains offer sites for drug attachment low-level systemic toxicity owing to their similarity to naturally occurring amino acids artificial skin substitutes limited applicability as biomaterials due to limited solubility and processsibility polymers containing more than three or more amino acids may trigger antigenic response

28. Other polymers Poly( cyanocrylates ) – used as bioadhesives – use as implantable material is limited due to significant inflammatory response Poly( phosphazenes ) – inorganic polymer – backbone consists of nitrogen-phosphorus bonds – use for drug delivery under investigation

29. Polymer Degradation Polymer degradation:- change of properties tensile strength, colour, shape and etc of polymer –based product under the influence of one or more environmental factors: heat , light or chemicals (acids/alkalis and salt)

30. Chemical degradation Degradation by hydrolysis to give lower molecular weight molecules. Hydrolysis takes place in the presence of water containing acid or base Biological degradation Biologically degraded by microorganism to give lower molecular weight Mechanical degradation polymer chain is ruptured by mechanical means. The effect is to reduce the polymer molecular mass. Chlorine induce cracking Chlorine – highly reactive gas that attack susceptible polymers such as acetal resin and polybutylene pipe work Thermal degradation Molecular deterioration as a result of overheating by breaking down its molecular chain Photo degradation Known as weathering process that resulting in discoloration and loss of mechanical properties Degradation

31. Reaction Paths of Polymer Degradation Mineralization Process Small variations of polymer chemical structures effects its biodegradability Biodegradability depend on molecular weight, molecular form and crystallinity Increase in molecular weight lead to decrease in biodegradibility Enzymes ( extracellular & Intrcellular depolymerases ) involved in depolymerization process

32. The term ‘ Biodegradation ’ is limited to the description of chemical processes which is chemical changes that alter the molecular weight or solubility of polymer ‘ Bio-erosion ’ is restricted to physical processes that result in weight loss of a polymer device Two types of bio-erosion of polymers are bulk erosion and surface erosion

33. Mechanism of Biodegradable Polymers

34. Types of bioerosion Bulk erosion Happens throughout the sample Ingress of water faster than the rate of degradation Ex: Polylactic acid (PLA)

35. BULK EROSION

36. Types of bioerosion - Cont Surface erosion Sample eroded from the surface Mass loss is faster than the ingress of water in the bulk Ex: Polyanhydrides

37. CLEAVAGE OF CROSSLINK TRANSFORMATION OF SIDE CHAINS CLEAVAGE OF BACKBONE ENZYMATIC DEGRADATION Enzymatic degradation – mediated by water, enzymes and microorganisms.

38. ADVANTAGES OF BIODEGRADABLE POLYMERS Decrease in dosing frequency Localized delivery of drug Sustained delivery of drug Stabilization of drug Reduce side effects Improved patient compliance Controllable degradation rate

39. Medical Applications of Biodegradable Polymers Wound management Sutures Staples Clips Adhesives Surgical meshes Orthopedic devices Pins Rods Screws Tacks Ligaments Dental applications Guided tissue regeneration Membrane Void filler following tooth extraction Cardiovascular applications Stents Intestinal applications Anastomosis rings Drug delivery system Tissue engineering

40. Polymers are everywhere Polymer degradation reducing molecular weight, destroyed crystallinity and diminish physical properties of polymers Most biodegradation is enzymatic hydrolysis or oxidation Landfill is still a problem! CONCLUSION

41. Glossary of Terms Biodegradable plastics : Plastics that will fully decompose to carbon dioxide, methane, water, biomass and inorganic compounds under aerobic and anaerobic conditions Aerobic decomposition : Biological decomposition in the presence of oxygen or air, where carbon is converted to carbon dioxide and biomass Anaerobic decomposition : Biological decomposition in the absence of oxygen or air, where carbon is converted to methane and biomass Biological decomposition : Decomposition under the influence of biological system Biomass : Substance of biological origin, with the exception of geological formations and fossilized biological matter Bioplastics : Plastics that are biodegradable and/or biomass-based OXO-Biodegradable : Degradation resulting from oxidative and cell mediated phenomena either simultaneously or successively Biopolymers : Polymers produced by living organism Biodegradation : A biological agent (an enzyme, microbe or cell) responsible for degradation Bioerosion : A water-insoluble polymer that turns water soluble under physiological conditions without regard to the mechanism involved during erosion. Bioerosion contains both physical (such as dissolution) and chemical processes (such as backbone cleavage). Bioresorption , Bioabsorption : Polymer or its degradation products removed by cellular activity

42. REFERENCE Kumar, A. A., Karthick , K., & Arumugam , K. P. (2011). Properties of biodegradable polymers and degradation for sustainable development. International Journal of Chemical Engineering and Applications ,  2 (3), 164. Krzan , A. (2012). Biodegradable Polymer and Plastic. Leja , K., & Lewandowicz , G. (2010). Polymer biodegradation and biodegradable polymers—a review.  Polish Journal of Environmental Studies , 19 (2), 255-266. Premraj , R., & Doble , M. (2005). Biodegradation of polymers.  Indian Journal of Biotechnology ,  4 (2), 186-193. Vroman , I., & Tighzert , L. (2009). Biodegradable polymers.  Materials ,  2 (2), 307-344.

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