Block copolymers by combination of LAP and RAFT polymerization
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Transcript of Block copolymers by combination of LAP and RAFT polymerization
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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
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Background
Living anionic polymerization◇ Excellent control◇ Pure reactants◇ Strict reaction conditions◇ Limited range of monomers (styrene, diene) Elastomer: PB, PI…… Thermoplastic elastomer: SBS
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RAFT polymerization
◇ Rather good control◇ Wide range of monomers◇ Wide range of operating conditions
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Combination of LAP and RAFT
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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%
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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
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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
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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
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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.
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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
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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.
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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
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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
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Conclusion and discussion
◇ Styrene homopolymerizatio gives less inhibition in chain extension of P(SEP)-RAFT agent with rather high MW.DRI UV-305nm
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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.
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Future work and recommendations
◇ The reaction conditions to be optimized.◇ Alternative way to be proposed. ……”Click Chemistry”?
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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
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Thanks for your attention and time!
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Questions???
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A typical Route
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(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