Block copolymers by combination of LAP and RAFT polymerization

Wang Hui Fudan Univ. China Ellen Donkers Lab of Polymer Chemistry, TU/eBert Klumperman the Netherlands

Background

Living anionic polymerization◇ Excellent control◇ Pure reactants◇ Strict reaction conditions◇ Limited range of monomers (styrene, diene) Elastomer: PB, PI…… Thermoplastic elastomer: SBS

RAFT polymerization

◇ Rather good control◇ Wide range of monomers◇ Wide range of operating conditions

Combination of LAP and RAFT

Model reaction with low MW RAFT agent

[Styrene]=[maleic anhydride]=1MReaction temperature: 85 ْC

Initiator: Vazo 88[RAFT]/[Vazo 88]=10

Solvent: MEK/Toluene (1/2)

Linear increase of Mn with conversionFinal PDI=1.16Final conversion=95%

Chain extension of P(EB)-macro-RAFT

MWmacro-RAFT=4000 g/mol[Styrene]=[maleic anhydride]=1MReaction temperature: 85 ْCInitiator: Vazo 88[RAFT]/[Vazo 88]=10Solvent: MEK/Toluene (2/1)

Predictable MW and linear increase of Mn with conversionFinal conversion=93%PDI macro-RAFT=1.03PDI final product=1.15

Chain extension of P(B)-macro-RAFT

MWmacro-RAFT=3500 g/mol[Styrene]=[maleic anhydride]=1MReaction temperature: 85 ْCInitiator: Vazo 88[RAFT]/[Vazo 88]=10Solvent: MEK/Toluene (2/1)

linear increase of Mn with conversionFinal conversion=48%PDI macro-RAFT=1.03PDI final product=1.37Cross-linking after long reaction time

Chain extension of P(SB)-macro-RAFT

MWmacro-RAFT=4000 g/molMW styrene block=2000 g/mol[Styrene]=[maleic anhydride]=1MReaction temperature: 85 ْCInitiator: Vazo 88[RAFT]/[Vazo 88]=10Solvent: MEK/Toluene (2/1)

Linear increase of Mn with conversionFinal conversion=89%PDI macro-RAFT=1.07PDI final product=1.57

Chain extension of P(SB)-macro-RAFT with rather high MW

MWmacro-RAFT=70000 g/molMW styrene block=60000 g/mol[Styrene]=[maleic anhydride]=0.3MReaction temperature: 85 ْCInitiator: Vazo 88[RAFT]/[Vazo 88]=5Solvent: MEK/Toluene (1/1)

If MW of butadiene block is 60000, reaction was stopped in 2 hours, due to the intensive gelation.

Chain extension of P(SEP)-macro-RAFT with rather high MW

MWmacro-RAFT=70000 g/mol, MW styrene block=10000 g/mol[Styrene]=[maleic anhydride]=1MReaction temperature: 85 ْCInitiator: Vazo 88, [RAFT]/[Vazo 88]=5Solvent: MEK/Toluene (1/1)

UV-305nmDRI

Conclusion and discussion

◇ Block copolymers were prepared by combination of LAP and RAFT polymerization, starting from different macro-RAFT agents without too high MW.

◇ Double bonds had some influences on the polymerization in RAFT process. The higher content of PB block is, the sooner cross-linking will take place.

Conclusion and discussion

◇ High viscosity does not effect the RAFT polymerization.MWmacro-RAFT=70000 g/molMW styrene block=60000 g/mol[styrene]=[maleic anhydride]=1M[RAFT]/[vazo 88]=10Solvent: MEK/toluene=1Reaction temperature: 85 ْC

Conclusion and discussion

◇ Macro-RAFT agents with too high MW may act as inhibitor in RAFT polymerization.

P(S-EP)-CH2CH2OC

O CCH3

CH3

SC

SC12H25

S

+ CN

P(S-EP)-CH2CH2OC

O CCH3

CH3

SC

SCN

SC12H25

+CN

C SC12H25

S

SP(S-EP)-CH2CH2O

CO

CCH3

CH3

Conclusion and discussion

◇ Styrene homopolymerizatio gives less inhibition in chain extension of P(SEP)-RAFT agent with rather high MW.DRI UV-305nm

Conclusion and discussion

◇ Reactive center-tertiary carbon radical may not work well in the RAFT polymerization.

New RAFT agent with a secondary living group has been synthesized and tested in the same way.

Future work and recommendations

◇ The reaction conditions to be optimized.◇ Alternative way to be proposed. ……”Click Chemistry”?

AcknowledgementProf. Daoyong ChenProf. Ming JiangProf. Zhengzhong Shao……Department of Macromolecular ScienceFudan UniversityEllen DonkersDr. Bert KlumpermanProf. Cor KoningProf. P.J. Lemstra Edgar Karssenberg……Eindhoven University of TechnologyDutch Polymer Institute

Thanks for your attention and time!

Questions???

A typical Route

(VII) Dkt

+ PP

R + P

R + R

(I) Initiator kd 2 I

(II) I + M ki Pm

(III) +S S

R

Z

PmS S

Z+Pm

kaddkfrag

PmS S

R

Z

k R

(IV) + MR ki Pn

(V) + MPn kp Pn+1

(VI) +S S

Pm

Z

PnS S

Z+Pn

kaddkfrag

PnS S

Pm

Z

kfrag

kaddPm

Proposed Mechanism of RAFT