RAFT copolymerization of alginate-derived macromonomers - synthesis of a well-defined poly(HEMAm)-graft-(1 → 4)-α-L-guluronan copolymer capable of ionotropic gelation

The aqueous RAFT copolymerization of methacrylamide- and methacrylate-functionalized (1 -> 4)-alpha-L-guluronan and (1 -> 4)-beta-d-mannuronan macromonomers with N-(2-hydroxyethyl)methacrylamide afforded synthetic-g-polysaccharide copolymers with a predetermined and well-defined molar mass ("grafting through" approach). One such polymer featuring guluronan graft chains of X-n = 21 was able to undergo ionotropic gelation in the presence of Ca2+ ions and to form a soft hydrogel in spite of the fairly low molar mass (M-n = 77 000 Da). The high yield synthesis of a new methacrylate-functionalized (1 -> 4)-alpha-L-guluronan is also reported.