Block and star block copolymers by mechanism transformation - X. Synthesis of poly(ethylene oxide) methyl ether/polystyrene/poly(L-lactide) ABC miktoarm star copolymers of by combination of RAFT and ROP

Poly(ethylene oxide) methyl ether/polystyrene/poly(L-lactide) (NIPEO/PSt/PLLA) ABC miktoarm star copolymers were synthesized by combination of reversible addition-fragmentation transfer (RAFT) polymerization and ring-opening polymerization (ROP) using bifunctional macro-transfer agent, MPEO with two terminal dithiobenzoate and hydroxyl groups. It was prepared by reaction of MPEO with maleic anhydride (MAh), subsequently reacted with dithiobenzoic acid and ethylene oxide. RAFT polymerization of St at 110 degreesC yielded block copolymer, MPEO-b-PSt KMPEO)(PSt)-CH2OH], and then it was used to initiate the polymerization Of L-lactide in the presence of Sn(OCt)(2) at 115 degreesC to produce ABC miktoarm star polymers, s+[(MPEO)(PSt)(PLLA)]. The structures of products obtained at each synthetic step were confirmed by NMR and gel permeation chromatography data. (C) 2004 Elsevier Ltd. All rights reserved.