Preparation and characterization of poly(ethylene glycol)-g-chitosan with water- and organosolubility

A new scheme was proposed for synthesizing poly(ethylene glycol)-g-chitosan (PEG-g-CS), where methoxy poly(ethylene glycol) iodide (MPEG-I) (Mn 2000) was used for N-substitution of triphenylmethyl chitosan (TPM-CS) in organic medium. The graft copolymers were obtained by subsequent removal of protecting groups with dichloroacetic acid. By varying PEG-I/TPM-CS feed ratio, the grafting levels (GL) of PEG can be adjusted. The chitosan derivatives were characterized by FTIR, 1H NMR, 13C NMR and DSC. All the copolymers were soluble in water over wide pH range. Furthermore, organosolubility of the hybrids in DMF and DMSO was also achieved when the DS value more than 24%. The lysozyme degradation rate of the copolymers in aqueous neutral medium decreased with the increase of GL value.