polymers

1. ENVIRONMENT FRIENDLY
POLYMERS

2. Stone Age
Bronze Age
Copper Age
Iron Age
Steel Age
Plastic Age
Biopolymer Age ???
Development of Human Kind

3. Biopolymers
Environmentally Benign Polymers
A novel class of materials ?
A new invention?
At best a renaissance:
first type of polymers used by human kind:
animal hides, cellulose, silk, wool

4. NATURAL BIODEGRADABLE POLYMERS

5. Enzymatic hydrolysis

6. Synthetic biodegradable polymers

7. Biodegradable Polymers
• Carbonyl bond to
O
N
S
R1 C X
O
R2
O
H2
R1 C OH
O
+HX R2
Where X= O, N, S
R1 C O
O
R2
Ester
R1 C NH
O
R2
Amide
R1 C S
O
R2
A.
Thioester

8. X C X'
O
R2
R1
O
H2
+ HX' R2
X C OH
O
R1
Where X and X’= O, N, S
B.
O C O
O
R2
R1 NH C O
O
R2
R1 NH C NH
O
R2
R1
Carbonate Urethane Urea
C. R1 C X
O
C
O
R2
O
H2
+
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
Biodegradable Polymers

9. Biodegradable Polymers
• Acetal:
Hemiacetal:
• Ether
• Nitrile
• Phosphonate
• Polycyanocrylate
O
H2
+
C
O
H H
R' OH
O C O
H
H
R R' R OH +
O
C
C
C C
C
OH
OH
OH
OH
OH OH
C
C
C C
OH
OH
OH
OH
H2O
+
C==O
H
H2O
R C O C R'
H H
H H
O
H2
R C OH
H
H
R' C OH
H
H
+
R C R
C N
H
R C R
C O
H
N
H2
R C R
C O
H
O
H
O
H2 O
H2
RO P OR'
O
OR''
O
H P OH
O
OR''
O
H2
+ +
R OH O
H R'
R C C C C R'
CN
C
OR''
CN
H
H
O C
OR'''
O
H
H
O
H2
R C C C
CN
C
OR''
H
H
O
H
H
OH C R'
CN
C
OR'''
O
+

10. What is Polymer Degradation?
polymers were synthesized
from glycolic acid in 1920s
At that time, polymer degradation was
viewed negatively as a process where
properties and performance deteriorated
with time.

11. Degradation Mechanisms
 Enzymatic degradation
 Hydrolysis
(depend on main chain structure: anhydride >
ester > carbonate)
 Homogenous degradation
 Heterogenous degradation

12. Degradation can be divided into 4
steps:
 water sorption
 reduction of mechanical properties
(modulus & strength)
 reduction of molar mass
 weight loss

13. Degradation Schemes
 Surface erosion (poly(ortho)esters and
polyanhydrides)
 Sample is eroded from the surface
 Mass loss is faster than the ingress of water into the
bulk
 Bulk degradation (PLA,PGA,PLGA, PCL)
 Degradation takes place throughout the whole of
the sample
 Ingress of water is faster than the rate of
degradation

14. Erodible Matrices or Micro/Nanospheres
 (a)
Bulk-eroding system
 (b)
Surface-eroding system

15. Polymer Degradation by Erosion

16. 4.Factors Affecting Biodegradation:
1. Effect of polymer structure:
 The hydrolyzable linkage in polymer chain easily biodegradable.
Ex) amide, Urea, Ureathane linkages.
 The substituents in polymer chain increase biodegradability.
Ex) poly(hexamethylene-a-benzylmalonamide) By
chymotrypsin.
 Flexibility of polymer affect the biodegradation.
Ex) PET lower degradable than aliphatic polyesters.
2. Effect of polymer morphology
 Depends on Crystallinity of the polymer and packing factor
 Depends on the copolymer melting points
3.Effect of Molecular Weight
 High molecular weight immune the microbial attack.
Ex) PP, PE, PVC

17. 3. Effect of radiation and chemical treatments
Photolysis with UV and ray irradiation leads to cleavage or cross linking.

18. MODE OF BIODEGRADATION
Biological agents responsible for the deterioration of polymer
substances.
Three types of Biological agents
 Fungi
80,000 species are present.
It need Certain conditions to degradation
Ex) Aspergillus niger
 Bacteria
Ex) Schizomycetes
 Enzymes are biological catalysts
Three dimensional structure with active site.

19. Applications:
There are three major areas;
• 1. Medical applications
 To replace tissues of nonfunctional as in-joint replacements, artificial heart
valves and arteries, tooth reconstruction.
 To assist in the repair of tissue, including the obvious sutures but also
bone fracture plates.
 To replace all or part of the function of organs such as haemodialysis,
oxygenation, heart, liver, pancreas.
 To deliver drugs to the targeted sites.
 Artificial skin.
2. Agricultural applications
 Agricultural mulches
 Controlled release of agricultural chemicals
 Agricultural planting containers.
3. Packaging.

20. References:
 Prog. Polym. Sci., vol. 23, 1273-1335, 1998
 Polymer chemistry by Charles E. Carraher.
 Text book of polymer science and technology- P. Ghosh
 Fukuda, K., An overview of the activities of the
Biodegradable Plastic Society, in Biodegradable polymers and
Plastics, ed. M. vert et al. Royal Society of Chemistry, 1992. p.
169

22. Mechanisms:

23. Look at the changes you could make…
It only takes a few
minutes to recycle!!!