Thermoresponsive glycopolymers via controlled radical polymerization

New glycomonomers 3'-(1',2':5',6'-di-O-isopropylidene-alpha-D-glucofuranosyl)-6-methacrylamido hexanoate (MAIpGlcC(5)) and 3'-(1',2':5',6'-di-O-isopropylidene-alpha-D-glucofuranosyl)-6-methacrylamido undecanoate (MAIpGlcC(10)) with hydrophobic spacer units were synthesized and their homopolymers, as well as random copolymers with N-isopropylacrylamide (NiPAAm) were prepared in varying compositions. The acidolysis of the isopropylidene protection groups of the polymers gave well-defined sugar-containing water-soluble homopolymers (PMAGlcC(n), n = 5,10) and copolymers. By using the reversible addition-fragmentation chain transfer (RAFT) process, it was possible to afford these copolymers with a polydispersity index (PDI) of 1.1-1.5. Furthermore, NiPAAm homopolymers with an active chain transfer unit at the chain end could be prepared by RAFT, which were used as macro-chain transfer agents (macro-CTAs) to prepare a variety of sugar containing responsive block copolymers from new glycomonomers by the monomer addition concept. The cloud points of the aqueous solutions of the copolymers were strongly affected by the comonomer content, spacer chain length of the glycomonomer, and the chain architecture of the copolymers. Especially by the block copolymer concept, glycopolymers with lower critical solution temperatures (LCSTs) in the physiologically interesting range could be realized. [GRAPHICS]