Polymer Synthesis and Modification by Enzymatic Catalysis

Muttaqin23 June 2009

History Overview

Enzymatic reactions have been widely used since 1980s

Two major directions of polymerization catalyst : Acids-Bases Transition metal

Enzymatic polymerization

Motivation

Synthesis and modification of polymers

using enzymatic catalysis for better

performance and environment

Outline Introduction Hydrolase Enzymes

Enzymatic polymerization Modification of polymers

Applications Disadvantages of the enzymatic

method Conclusion References

Introduction :Characteristics of Enzymatic Synthesis

Two important aspects on enzymatic reactions :1. Key and Lock Theory (Fischer : 1894)

Introduction :Characteristic of Enzymatic Synthesis

2. Lowering the activation energy (Pauling)

Reaction Profile

Key Factor :Design and synthesisan artificial monomer

Introduction :Advantages of enzymatic polymerization

Precise control of polymer structures

(regioselectivity, chemoselectivity,

stereochemistry)

No need protection and deprotection

Clean process, mild condition, environmental

friendly

Produce biodegradable polymers (many

cases)

Introduction :Classification of Enzymes

Enzymes Examples Enzymes

Typical Polymers-1

Typical Polymers-2

1. Oxidoreductase

PeroxidaseTyrosinaseGlucose oxidase

Polyphenols, polyanilines, Vynyl polymers

Polysaccharides, polypeptides (protein)

2.Transferase

GlycosyltransferaseAcyltransferase

Polysaccharides, cyclic olygosaccharides, polyester

Polysaccharides, polypeptides (protein)

3.Hydrolase

Glycosidase (Cellulase, chitinase, amylase, etc)LipasePeptidase

Polysaccharides, polyester, polyamides, polycarbonates, poly(amino acid)s

Polysaccharides, polypeptides (protein)

4. Lyase DecarboxylaseAdolase, Dehydrase

polysaccharides

5. Isomerase RacemaseEpimerase

6. Ligase Acyl CoA synthetase

Enzymatic polymerization :Hydrolase – Lipase Enzyme

Lipase is an enzyme that catalyzes the

hydrolysis of fatty acid ester

Lipase can be used to catalyse

polymerization reactions, such as

Polyester

The reaction of lipase-catalyzed

polymerization can be done by ROP or

Polycondensation

Enzymatic polymerization :Reaction Mechanism of ROP

Enzymatic polymerization : Reaction Mechanism of ROP

The rate determining step is the EM formation

Lypase

Enzyme

Lypase

Enzyme

O C

O

(CH2)m O H

Enzyme-activated monomer, EM

H O R H O (CH2)m C

O

OR

Lypase

Enzyme

Lypase

Enzyme

OH

Initiation :

Lypase

Enzyme

Lypase

Enzyme

O C

O

(CH2)m O H H O (CH2)m Cn

O

OR H O (CH2)m Cn+1

O

OR

Lypase

Enzyme

Lypase

Enzyme

OH

Propagation :

Enzymatic polymerization :Polyester via Polycondensation

Enzymatic Polymerization :Enantioselective and Chemoselective

Enantioselective : - Prefer to produce one

enantiomer to another

Chemoselective :- Selective to a functional group

OO

OH3C

O O

OCH3

n

OO

OH3C

*

racemic monomer(MOHEL)

S-enriched R-enriched(Unreacted)

Lipase

O

O

O

O

O

O

n

2-methylene-4-oxa-12-dodecanolide

Lipase CA ROP

Modification of Polymer :By Enzymatic Catalysis

Purpose Improve the polymer properties

Produce polymer with environmental

friendly

Fulfill market demand

Modification of Polymer :Polysaccharides by lipase enzyme

Applications : Polysaccharides

Biocompatible, biodegradable, and non-toxic• Use : Biomedical purposes, such as for drug

delivery. Paper industries, water treatment, and other industrial applications

Applications : Polyester

Usefulness : Packaging, textile, resin,

liquid crystal display, plasticdisplay, etc

Disadvantages of the Enzymatic Method

1. Limitation of substrates

2. Availability and cost of enzymes

3. Reaction : ofen slower than chemical methods

Conclusion

• The enzymatic reaction takes place

under mild condition and is excellent in

controlling polymer structures

• The enzymatic reaction also reduces

environmental problems

• However, this reaction is restricted by

availability of substrates and enzymes

References

1. Macromolecule Engineering. Precise Synthesis, Material

Properties, Application. Edited by K. Matyjaszewski, Y.

Gnanou, and L. Leiber. Copyright © 2007 WILEY-VCH

Verlag GmbH & Co. KGaA, Weinheim

2. Physical chemistry for the life Sciences. P. Atkins, J. d.

Paula. © 2006 W.H. Freeman and Company 41 Madison

Avenue, New York.

3. Introduction to Polymer Science and Chemistry. M.

Chandra. Copyright © 2006 by Taylor & Francis Group,

LLC. CRC Press, New York

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