Synthesis of controlled-structure AB diblock copolymers of 3-O-methacryloyl-1,2:3,4-di-O-isopropylidene-d-galactopyranose and 2-(dimethylamino)ethyl methacrylate

We report herein the synthesis of hydrophilic-hydrophilic AB diblock copolymers of 3-O-methacryloyl-d-galactopyranose (MAGP) with 2-(dimethylamino)ethyl methacrylate (DMAEMA). These materials were obtained from precursor AB diblock copolymers of 3-O-methacryloyl-1,2:3,4-di-O-isopropylidene-d-galactopyranose (MAIpGP) and DMAEMA. The well-defined precursor block copolymers were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization in organic media employing dithiobenzoates as the mediating agents. We show that the homopolymerization of MAIpGP proceeds in a controlled fashion as judged by the linear pseudo-first-order kinetic plot, the linear relationship between the number average molecular weight (Mn) and the degree of conversion, and the resulting low polydispersity indices. Homopolymers of MAIpGP were employed as macro chain transfer agents for the preparation of the target AB diblock copolymers with DMAEMA. We show that PMAIpGP homopolymers are readily and quantitatively converted to the corresponding poly(3-O-methacryloyl-d-galactopyranose) (PMAGP) species according to a literature procedure. In a control experiment we demonstrate that these deprotection conditions do not adversely affect a DMAEMA homopolymer.