block copolymers by combination of lap and raft polymerization wang hui fudan univ. china ellen...
TRANSCRIPT
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]=1M
Reaction temperature: 85 ْC
Initiator: Vazo 88
[RAFT]/[Vazo 88]=10
Solvent: MEK/Toluene (1/2)
Linear increase of Mn with conversion
Final PDI=1.16
Final conversion=95%
Chain extension of P(EB)-macro-RAFT
MWmacro-RAFT=4000 g/mol[Styrene]=[maleic anhydride]=1
MReaction temperature: 85 ْC
Initiator: Vazo 88[RAFT]/[Vazo 88]=10
Solvent: MEK/Toluene (2/1)
Predictable MW and linear increase of Mn with conversion
Final conversion=93%
PDI macro-RAFT=1.03
PDI final product=1.15
Chain extension of P(B)-macro-RAFT
MWmacro-RAFT=3500 g/mol[Styrene]=[maleic anhydride]=1
MReaction temperature: 85 ْC
Initiator: Vazo 88[RAFT]/[Vazo 88]=10
Solvent: 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 ْC
Initiator: Vazo 88[RAFT]/[Vazo 88]=10
Solvent: 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 ْC
Initiator: Vazo 88[RAFT]/[Vazo 88]=5
Solvent: 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]=10
Solvent: MEK/toluene=1
Reaction 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 C
CH3
CH3
SC
SC12H25
S
+ CN
P(S-EP)-CH2CH2OC
O C
CH3
CH3
SC
SCN
SC12H25
+CN
C SC12H25
S
SP(S-EP)-CH2CH2O
CO
C
CH3
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”?
Acknowledgement
Prof. Daoyong ChenProf. Ming JiangProf. Zhengzhong Shao……Department of Macromolecular ScienceFudan University
Ellen 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) D
kt
+ PP
R + P
R + R
(I) Initiator kd 2 I
(II) I + M ki Pm
(III) +
S SR
Z
PmS S
Z+Pm
kadd
kfragPm
S SR
Z
k R
(IV) + MR ki Pn
(V) + MPn kp Pn+1
(VI) +
S SPm
Z
PnS S
Z+Pn
kadd
kfragPn
S SPm
Z
kfrag
kaddPm
Proposed Mechanism of RAFT