Modification Of Chitosan & Carboxymethyl Chitosan Grafted With Monomethoxy Poly(Ethylene Glycol)

In order to improve the poor solubility of chitosan, monomethoxy poly(ethylene glycol) grafted chitosan(CTS-g-MePEG) were prepared by the reacting of aldehyded monomethoxy poly(ethylene glycol) and the 2-amino functions of chitosan. The obtained comb-shaped CTS-g-MePEG products present good watersolubility. Elemental analysis,IR spectroscopy and TEM methods were used to estimate the properties of the grafted products. The results indicate that the prepared CTS-g-MePEG can self-assemble into micelles in distilled water solution. Moreover, the grafted chitosan presents different rheological property from chitosan in acidic medium. Using the same method, the present paper also prepared monomethoxy poly(ethylene glycol) grafted carboxymethyl chitosan(CMCTS-g-MePEG), which can be dispersed in water over all pH range. The rheological property, amphoteric polyelectrolyte property and the complexing behavior of CMCTS and CMCTS-g-MePEG with water-soluble chitosan were investigated. In order to remain the free amino groups on chitosan, chitosan-O-monomethoxy poly(ethylene glycol) was prepared by the grafting of MePEG-NCO to the hydroxyl groups of N-phthaloyl chitosan. The phthaloyl groups were removed with hydrazine monohydrate to regenerate the free amino groups. The results showed that the amino groups can be protected by phthalic anhydride and MePEG can be grafted onto CTS at the hydroxyl groups. But unfortunately, the hydroxyl groups were partly deoxidised during the process of deoxidizing phthaloyl groups by hydrazine monohydrate.