Well-defined diblock glycopolymers from RAFT polymerization in homogeneous aqueous medium

Reversible addition-fragmentation chain transfer polymerization was applied to the synthesis of well-defined diblock glycopolymers carrying different cyclic carbohydrates on the two blocks. The macroRAFT agents poly(methyl 6-O-methaeryloyl-alpha-D-glucoside) dithiobenzoate and poly(2-methacryloxyethyl glucoside) dithiobenzoate were prepared by RAFT polymerization of the corresponding glycomonomers with (4-cyanopentanoic acid)-4-dithiobenzoate as the chain transfer agent. The reactions were stopped around 85% conversion in order to preserve the highest possible end-of-chain-functionality and the glycopolymers were isolated by precipitation in methanol. Chain extension with 2-methacryloxyethyl glucoside and methyl 6-O-methacryloyl-alpha-D-mannoside afforded poly(methyl 6-O-methacryloyl-alpha-D-glucoside-block-2-methacryloxyethyl glucoside) and poly(2-methacryloxyethyl glucoside-block-methyl 6-O-methacryloyl-alpha-D-mannoside), respectively, having a predetermined molecular weight and narrow polydispersity (PDI <= 1.20). The structure of the prepared polymers was confirmed by proton and carbon NMR and their thermal properties investigated via DSC.