Preparation and characterization of a poly(ethylene glycol) grafted carboxymethyl konjac glucomannan copolymer

Carboxymethyl konjac glucomannan (CKGM) grafted methoxy poly(ethylene glycol) (mPEG) (CKGM-g-mPEG) copolymer was prepared by reacting the CKGM with methoxy poly(ethylene glycol) amine in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]-carbodiimide (EDC) and N-hydroxysuccimide (NHS). By varying the mPEG-OCOCH2NH2/CKGM feed ratio, the degree of substitution (DS) of mPEG could be adjusted. The degree of substitution (DS) of mPEG into CKGM was calculated from TGA data. The chemical structure and physical properties of the products were identified by means of FT-IR, 1H NMR, DSC and TGA. Solubility and the viscosity tests showed that CKGM-g-mPEG has better solubility and lower viscosity at low shear frequency as compared to non-pegylated CKGM.