The Reaction Mechanism of Chitosan and Maleic Anhydride Grafted Maleic Acid

In order to meet the requirements of biomedical applications, suitable materials with good biocompatibility and excellent performance are needed. Chitosan is one of the prospective materials for the study of biological materials. Chitosan (Ch) is a natural polysaccharide extracted from chitin, and it is a raw material widely used in the research of biological materials.

In this paper, acetic acid and water were used as solvents to graft chitosan with maleic anhydride, and an eco-friendly functionalization process was carried out as shown in Figure 1. In addition, the mechanism of the grafting has been further studied. Using different concentrations of MA:Ch ratio and temperature, the total acid content and conversion rate of the grafted membrane were calculated.

Figure 1 Reaction mechanism of chitosan grafted maltose in water

Through Fourier Transform Infrared Spectroscopy (FTIR) analysis as shown in Figure 2, the success of the grafting of chitosan and maleose was verified. FTIR analysis showed that new ester groups appeared and amide groups shifted from the FTIR spectrum, indicating that esterification and amidation occurred during the grafting process.The results show that the increase of temperature will increase the conversion rate of chitosan. Further research on the interaction of chitosan with maleic anhydride remains to be done to understand the behavior and characteristics of chitosan and maleic acid. Since the actual interaction between the hydrated ammonium, carboxyl and amine groups is in equilibrium, another related study is required to measure the conversion.

Figure 2 FTIR spectra of maleic anhydride (a), Ch(b), unwashed Ac2170(c) and washed Ac2170(d)