+ All Categories
Transcript
Page 1: Group Transfer Polymerisation (GTP)

Group Transfer

Polymerization

(GTP)

Sujoy Saha (20101095)

Nikhil Y. L. K. (2009004)

Page 2: Group Transfer Polymerisation (GTP)

Brief Overview

• Introduction• Discovery of Method• Synthetic Routes• Mechanisms:

Then and Now• Applications• Pros and Cons • Paper (2)• Conclusion

Page 3: Group Transfer Polymerisation (GTP)

Introduction

• conjugate addition of silyl ketene acetals to α,β‐unsaturated carbonyl compounds

Organic Chemistry, Clayden, p-755

• Applied to alkylated methacrylate monomers and the initiator is a silyl ketene acetal.

• New monomer adds to the initiator and to the active growing chain in a Michael rxn.

• Discovered over 30 years ago at

• Anionic living polymerization- but active chain end is covalent

Page 4: Group Transfer Polymerisation (GTP)

Discovery- A Story

Webster et al at DuPont’s Central R&D

• Methacrylate block polymers useful in automobile

finishes.

• at -80°C by sequential polymerization of different

methacrylate monomers under “living” anionic

conditions.

• maintaining reactors at -80°C !!!

Page 5: Group Transfer Polymerisation (GTP)

•“living” anionic polymerization of methyl methacrylate with a 1,1-

diphenylhexyl anion containing a silyl protected –OH.

• trimethylsilyl ketene acetal could react with MMA to give polymer by a repetitive

Mukiayama reaction…..

• few unsuccessful reactions with Lewis acids such as BF3 etherate

• First production of PMMA by group transfer polymerization with ZnBr2 catalyst

• Name suggested by Trost

Discovery- A Story

Page 6: Group Transfer Polymerisation (GTP)

Synthetic Routes

• Always start with conjugate addition of silyl ketene acetal initiators

• Monomer: Methacrylates, Acrylates, Ketones, Nitriles, Carboxamides

-Nucleophilic Anions

KHF2

TASHF2Bu4NF

TASCN

Et4NCN

TASN3

-Lewis Acids

ZnBr2ZnI2ZnCl2(i-Bu2Al)2O

i-Bu2AlCl

Et2AlClWebster et al., J. Am. Chem. Soc. 1983, 105, 5706-5708

Sogah et al., Macromolecules, Vol. 20, No. 7, 1987

• Catalysts: Two choices

Page 7: Group Transfer Polymerisation (GTP)

Mechanisms

Page 8: Group Transfer Polymerisation (GTP)

Pros and Cons

• Advantages

1. Good for making blocks of

acrylates and methacrylates

2. Can be done at RT and

elevated T

3. Excellent architectural control

(stars, blocks, etc.)

4. Low PDIs (can get down to

1.03!)

5. No metallic or halide impurities

left over

6. No bad odors!

• Disadvantages

1. Cannot be done in presence of

water

2. Initiator still costly

3. Cannot use monomers with

acidic or active hydrogen

functional groups

Page 9: Group Transfer Polymerisation (GTP)

Spinelli, H.J. Prog. Org. Coat. 1996, 27, 255-260

Applications

• Pigment Dispersant

• Emulsion Stabilizers

• AB block co-polymerA = Hydrophilic BlockB = Hydrophobic Block

H2O

H2O

H2O

H2O

Page 10: Group Transfer Polymerisation (GTP)

Spinelli, H.J. Prog. Org. Coat. 1996, 27, 255-260

Applications

• Pigment Dispersant

• Emulsion Stabilizers

• AB block co-polymerA = Hydrophilic BlockB = Hydrophobic Block

H2O

H2O

H2O

H2O

Page 11: Group Transfer Polymerisation (GTP)

Group Transfer Polymerization of Acrylates and Methacrylates

using N-hetereocyclic Carbene Catalysts

- Scholten et al., Polymer Preprints 2007, 48(2),167

N-heterocyclic carbenes (NHCs) as potent catalysts

for GTP of methyl methacrylate and tert-butyl acrylate

Page 12: Group Transfer Polymerisation (GTP)

Conc: NHCs demonstrate equivalent activity and superior control in comparison

to bifluoride-catalyzed systems.

Results

Page 13: Group Transfer Polymerisation (GTP)

Group transfer polymerization of biobased unsaturated esters

-E. Kassi et al./ European Polymer Journal 49 (2013) 761–767

•(As the fossil resources dwindle) concerned with organic synthetic building blocks.

Page 14: Group Transfer Polymerisation (GTP)

Group transfer polymerization of biobased unsaturated esters

-E. Kassi et al./European Polymer Journal 49 (2013) 761–767

•(As the fossil resources dwindle) concerned with organic synthetic building blocks.

Page 15: Group Transfer Polymerisation (GTP)

Polymerization of Itaconic Acid esters

• can be obtained from “distillation” of citric acid.

• Attempted random block copolymerization of the pairs di(n-butyl)itaconate

(DBI) with methyl methacrylate (DBI-MMA) and 2-(dimethylamino)ethyl

methacrylate (DBI-MAEMA)

• Products were just DBI oligomers, whereas MMA and DMAEMA were not consumed.

• This indicated the greater reactivity of DBI compared to the methacrylates.

Page 16: Group Transfer Polymerisation (GTP)

• attachment of 1–2 DBI units to the second short block of DMAEMA

• DMAEMA-DBI combination corresponds to amphiphilic block

copolymers capable of forming micelles in water

Conc: nature designed unsaturated compounds are not inert

Polymerization of Itaconic Acid esters

Page 17: Group Transfer Polymerisation (GTP)

Conclusion

• Relatively new ‘quasi- living’ oxyanionic polymerization technique,

capable of the rapid, room-temperature polymerization of

α,β-unsaturated carbonyl compounds.

• Full of potential, still room for improvement

• Best method around for block polymers of methacrylate derivatives


Top Related