Cationic disulfide-functionalized worm gels.

The recent development of polymerization-induced self-assembly (PISA) has facilitated the rational synthesis of a range of diblock copolymer worms, which hitherto could only be prepared traditional post-polymerization processing in dilute solution. Herein we explore a new synthetic route to aqueous dispersions of cationic disulfide-functionalized worm gels. This is achieved the PISA synthesis of poly[(glycerol monomethacrylate--glycidyl methacrylate)]--poly(2-hydroxypropyl methacrylate) (P(GMA--GlyMA)-PHPMA) block copolymer worms reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion polymerization of HPMA. A water-soluble reagent, cystamine, is then reacted with the pendent epoxy groups located within the P(GMA--GlyMA) stabilizer chains to introduce disulfide functionality, while simultaneously conferring cationic character formation of secondary amine groups. Moreover, systematic variation of the cystamine/epoxy molar ratio enables either chemically cross-linked worm gels or physical (linear) primary amine-functionalized disulfide-based worm gels to be obtained. These new worm gels were characterized using gel permeation chromatography, H NMR spectroscopy, transmission electron microscopy, dynamic light scattering, aqueous electrophoresis and rheology. In principle, such hydrogels may offer enhanced mucoadhesive properties.