Biodegradable polymers by madhuri phute

BIODEGRADABLE
POLYMERS
By :
Madhuri Phute
Biodegradation
Biodegradation is the process of converting
polymer material into harmless, simple, gaseous products
by the action of enzymes, micro-organisms and water.
Biodegradable Polymer
Biodegradable polymers degrade as a result of
natural biological processes, eliminating the need to
create a disposal system which can cause harm to our
environment.
INTRODUCTION
NEED FOR BIODEGRADABLE
POLYMERS
•
Polymers have become an essential part of our daily
life.
•
Having its numerous advantages, it finds it use in
every field.
•
But these polymer products account for approx. 150
million tons of non biodegradable waste every year.
•
Such large amounts of waste leads to various
problems, not to mention, a general lack of
cleanliness in the neighbourhood.
•
Inert

•
Permeability
•
Non-toxicity
•
Bio-compatibility
•
Tensile strength
•
Mechanical strength
•
Controlled rate of degradation
Characteristics Of
Biodegradable Polymers
BIODEGRADATION
ENZYMATIC
DEGRADATION
COMBINATIONHYDROLYSIS
BULK EROSION
SURFACE EROSION
Mechanism Of Biodegradable Polymers
ENZYMATIC DEGRADATION
Enzymatic degradation takes place with the
help of various enzymes.
The type of enzymes used for degradation
depends upon the type of polymer:
•
Fungi – ‘ Fusarium Moniliformae’
•
Yeast- ‘Cryptococcus

•
Enzymes from moulds such as ‘Penicillium’
POLYMER DEGRADATION AND
EROSION
Degradation Chain Cleavage
Erosion Loss of Mass
1. Bulk Erosion
2. Surface Erosion
Degradation in two Phases
1 Water penetration (Rate Determining)
-Attacking Chemical bonds
-Shorter water soluble fragments
2 Rapid loss of polymer
-Enzymatic attack
-Solubilisation
EROSION
Type I Erosion :
•
Evident with water soluble polymers cross linked to form three dimensional
network.
•
Cross linking still intact.
•
Network insoluble.
•
Swelling.
•
Solubilisation by cleavage of water soluble backbone or crosslinking
Type II Erosion :
•

Polymers first are water insoluble but converted to water soluble by
reaction with pendant group.
Type III Erosion :
•
Polymers with high molecular weight are broken down and transformed to
smaller water soluble molecules.
POLYMER DEGRADATION POLYMER EROSION
CHEMICAL STRUCTURE
(a) Functional Group
(b) Hydrophobicity
MORPHOLOGY
(a) Tensile strength
(b) Branching
PARTICLE SIZE
Larger the particle size slower the degradation
process.
FACTORS AFFECTING
BIODEGRADATION
BIODEGRADABLE
POLYMERS
•
Biopol
(Polyhydroxybutarate-hydroxyvalerate)
•
Polycaprolactone
•
Polylactic Acids
•
Polyglycolic Acids
•

Polydioxane
BIOPOL
BIOPOL is a copolymer of
3-hydroxy butyric acid and
3-hydroxy valeric acid.
PRODUCTION :
It is produced by
fermentation of
glucose by
Acaligenes
eutrophus
species.
POLYHYDROXYBUTARATE-
HYDROXYVALERATE
(PHB-HV)
•
It is a type of
Biopolymer.
•
Molecular Formula:
C27H42O12
•
Monomer Weight:
558.62 amu
Properties of Biopol :
•
Water insoluble and relatively resistant to hydrolytic degradation.
Good oxygen permeability.
•
Good ultra-violet resistance but poor resistance to acids and bases.

•
Soluble in chloroform and other chlorinated hydrocarbons.
•
Biocompatible and hence is suitable for medical applications.
•
Melting point 175°C., and glass transition temperature 2°C.
•
Tensile strength is 40 MPa close to that of polypropylene.
•
Sinks in water (while polypropylene floats), facilitating its anaerobic
biodegradation in sediments.
•
Nontoxic.
•
Less 'sticky' when melted, making it a potentially good material for
clothing in the future
POLYCAPROLACTONE
Polycaprolactone (PCL) is a biodegradable polyester.
Preparation of Polycaprolactone:
Properties Of Polycaprolactone:
•
It has a low melting point of around 60°C.
•
It has a glass transition temperature of about −60°C.
Uses Of Polycaprolactone:
•
The most common use of polycaprolactone is in the
manufacture of speciality polyurethanes.
•
Polycaprolactones impart good water, oil, solvent and

chlorine resistance to the polyurethane produced.
•
This polymer is often used as an additive for resins to
improve their processing characteristics and their end
use properties.
•
Being compatible with a range of other materials, PCL
can be mixed with starch to lower its cost and increase
biodegradability or it can be added as a polymeric
plasticizer to PVC.
Degradation Of Polycaprolactone:
•
PCL is degraded by hydrolysis of its ester
linkages in physiological conditions (such as in
the human body).
•
It has therefore received a great deal of
attention for use as an implantable biomaterial.
•
In particular it is especially interesting for the
preparation of long term implantable devices,
owing to its degradation which is even slower
than that of polylactide (or polylactic acid).
POLYLACTIC ACID
•
Polylactic acid or polylactide (PLA) is
a thermoplastic aliphatic polyester
derived from renewable resources, such
as corn starch, tapioca products (roots,
chips or starch) or sugarcane.

•
It can biodegrade under certain
conditions, such as the presence of
oxygen, and is difficult to recycle.
•
The name "polylactic acid" does not comply with IUPAC standard
nomenclature, and is potentially ambiguous or confusing,
because PLA is not a polyacid (polyelectrolyte), but rather a
polyester
Formation of Polylactic Acids:
Bacterial fermentation is used to produce
lactic acid from corn starch or cane sugar.
Uses of Polylactic Acids:

Mulch film made of PLA-blend
bio-flex
Biodegradable PLA cups
in use at an eatery
Due to PLA's relatively low
glass transition temperature,
PLA cups cannot hold hot
liquids. However, much
research is devoted to
developing a heat resistant
PLA.
POLYGLYCOLIC ACID
•
Polyglycolide or
Polyglycolic acid (PGA) is a
biodegradable, thermoplastic

polymer and the simplest linear,
aliphatic polyester.
•
It is a tough fibre-forming
polymer. Due to its hydrolytic
instability its use has been
limited.
•
It has a glass transition
temperature between 35-40 °C.
•
Its melting point is in the range
of 225-230 °C.
•
It also exhibits an
elevated degree of
crystallinity, around 45-
55%, thus resulting in
insolubility in water.
Preparation of Polyglycolic Acids:
Polyglycolide can be obtained through several different
processes starting with different materials:
•
Polycondensation of glycolic acid
•
Ring-opening polymerization of glycolide
•
Solid-state polycondensation of halogenoacetates
Degradation of Polyglycolic Acids:
•

Polyglycolide has hydrolytic instability due to the presence of the
ester linkage in its backbone.
•
The degradation process is erosive and appears to take place in
two steps during which the polymer is converted back to its
monomer glycolic acid:
1. First water diffuses into the amorphous (non-
crystalline) regions of the polymer matrix,
cleaving the ester bonds. 2. Second step
starts after the amorphous regions have been eroded, leaving the
crystalline portion of the polymer susceptible to hydrolytic attack.
When the crystalline regions collapse, the polymer chain dissolves.
•
When exposed to physiological conditions, polyglycolide is
degraded by hydrolysis, and broken down by certain enzymes.
•
The degradation product, glycolic acid, is nontoxic.
•
Studies undergone using polyglycolide have shown that the
material loses half of its strength after two weeks and 100% after
four weeks. The polymer is completely resorbed by the organism in
a time frame of four to six months.

POLY ESTERS

POLY PHOSPHO ESTERS

POLY ANHYDRIDES

POLY OLEFINS


POLY AMIDES
Biodegradable Polymers
For Controlled Drug Delivery
NATURAL POLYMERS
These are the polymers obtained from natural resources, and
are generally non-toxic.
NATURAL POLYMERS
PROTEINS Polysaccharides
Ex: COLLAGEN
ALBUMIN
FIBRIN
Ex : DEXTRAN
CHITOSAN
STARCH
ADVANTAGES : 1) Readily & Abundantly Available.
2) Comparatively Inexpensive.
3) Non toxic products.
4) Can be modified to get semi synthetic
forms.