Abstract:

BACKGROUND: Polyethylene glycol has been generally applied to improving water solubility of macromolecular materials not only for its favourable water solubility and biocompatibility but also for its hydrophily and flexibility.
OBJECTIVE: To improve chitosan hydrophily by selectively grafting polyethylene glycol to chitosan molecule chain.
METHODS: First, amino groups on chitosan chains were protected by copper ion. Second, the monomethoxy polyethylene glycol which hydroxyl was combined with hexamethylene diisocyanate became a novel macromonomer namely monomethoxy polyethylene glycol isocyanate. And then, the hydroxyl group of chitosan was selectively grafted by the macromonomer. Finally, the copolymer of chitosan grafted by poly(ethylene glycol) was synthesized. The effects of monomethoxy polyethylene glycol dosage on grafting ratio, grafting efficiency and swelling properties of chitosan grafted by poly(ethylene glycol) in water were studied.
RESULTS AND CONCLUSION: The graft ratio was increased with the increase of the amount of monomethoxy polyethylene glycol. Grafting efficiency reached the maximum, and it was about 24%, when the mass ratio of monomethoxy polyethylene glycol to chitosan was about 5. Equilibrium swelling degree was up to above 120%, when mass ratio of monomethoxy polyethylene glycol to chitosan was about 8.75. These findings suggest that the more the amount of the monomethoxy polyethylene glycol, the stronger was the swelling ability when chitosan grafted by poly(ethylene glycol) was soaked for the same time in water.