Graft polymerization of hydroxyethyl cellulose/poly(caprolactone) and determination of the substitution value of derivative group

With the protection technique of the trimethylsilyl (TMS) groups, ε-caprolactone (CL) was successfully grafted on hydroxyethyl cellulose (HEC) to prepare hydroxyethyl cellulose-graft-poly caprolactone (HEC-g-PCL). The structures of the intermediate product and the end product were carefully characterized by FT-infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR). The results confirm that the copolymer newly synthesized is as expected. The molar degree of substitution (MS) of HEC was determined by chemical titration, and the trimethylsilyl MS of the intermediate product and the repeated number of PCL grafting side chain were determined by 1H-NMR. Moreover, the grafting ratio of PCL side chain and grafting efficiency of CL were also ascertained. The investigation on the substitution values of derivative groups of raw material, intermediate product and end product will be beneficial to further research on the reaction mechanism of the graft copolymerization.