Amphiphilic poly(acrylic acid-b-styrene-b-isobutylene-b-styrene-b-acrylic acid)pentablock copolymers from a combination of quasiliving carbocationic and atom transfer radical polymerization

摘要

Amphiphilic poly(acrylic acid-b-styrene-b-isobutylene-b-styrene-b-acrylic acid)(PAA-PS-PIB-PS-PAA)block copolymers were prepared using a combination of quasiliving carbocationic and atom transfer radical polymerization(ATRP)techniques.Poly(styrene-b-isobutylene-b-styrene)(PS-PIB-PS)block copolymer macroinitiators with targeted molecular weights and high degrees of chain end functionality(F_n > 1.7)were prepared by quasiliving carbocationic polymerization of isobutylene followed by sequential addition of styrene.Poly(tert-butyl acrylate-b-styrene-b-isobutylene-b-styrene-b-tert-butyl acrylate)(PtBA-PS-PIB-PS-PtBA)pentablock terpolymers with targeted molecular weights and low polydispersities(PDIs)were synthesized from the PS-PIB-PS macroinitiators via ATRP of tBA using either a Cu(I)Cl/l,l,4,7,7-pentamethyldiethylenetriarnine(PMDETA)or Cu(I)Cl/Aris[2-(dimethylamino)ethyl]amine(Me_6TREN)catalyst system.Deprotection of the tert-butyl groups using trifluoroacetic acid at 25 deg C resulted in the formation of PAA-PS-PIB-PS-PAA pentablock terpolymers.Comonomer composition of the final terpolymers,determined by ~1H-NMR spectroscopy,was very close to theoretical.