Chitosan is one of the most important biopolymers on earth, and is derived from the second most abundant natural polymer, chitin. Chitosan, valued for its biocompatibility, biodegradability, and biological tolerance, finds applications in the biomedical and pharmacy fields including for example with drug delivery systems. However its properties and applications in these fields could be improved if functional groups or polymer chains are covalently attached to modify its properties. PEGylation of chitosan has been used to enhance its solubility, biocompatibility and absorption since PEG has low toxicity and is biocompatible. In this research, PEGlytation of chitosan with well-defined poly(poly(ethylene glycol) methyl ether methacrylate), polyPEGMA, via living radical polymerization using nitroxide chemistry and a “grafting to” approach is reported for the first time. Chitosan was first functionalized with glycidyl methacrylate (GMA) yielding CTS-g-GMA. Nitroxide-terminated polyPEGMA was then prepared via nitroxide-mediated polymerization (NMP) in water. These polyPEGMA chains were then grafted to the functionalized chitosan in aqueous media. PEGylation of the chitosan was carried out on the hydroxyl groups on the chitosan molecule, thereby preserving the amino functionality for subsequent reaction or functionalization. The grafting to procedure enabled grafting well-defined graft modified chitosan. The resulting properties of the PEGylated chitosan may be modified simply by the changing the molecular weight of the polyPEGMA made via NMP. A unique feature of our research is that both the graft polymer synthesis and grafting to step were performed in aqueous media, thereby avoiding the use of toxic solvents.

PEGylation of chitosan via nitroxide chemistry in aqueous media

253rd National Meeting (2017)

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