Hydrogels based on pullulan derivatives crosslinked via a "living" free-radical process

Abstract

Partially methacrylated pullulan was crosslinked by means of conventional and "living" radical polymerisations using, in the latter case, the reversible additionfragmentation chain-transfer technique (RAFT). Several hydrogels were synthesised using methacrylated pullulan samples with different degrees of substitution, at different conversions using the RAFT technique for the first time. Network formation was monitored by means of rheological measurements and the ensuing samples characterised by swelling experiments and morphological studies. Hydrogels prepared by the "living" radical polymerisation always swelled to a greater extent than conventional gels having the same double bond conversion. The difference was more pronounced at low conversion. Scanning electron microscopy also showed that the porosity of the gels could be effectively regulated with the "living" polymerisation.