Preparation of Chitosan Maleic Salt and Properties of Its Film

Chitosan maleic salt (Ch-Ma) was prepared by a semi-wet grinding method and the Ch-Ma film was prepared by casting method. The structure of Ch-Ma and its film were characterized by FT-IR spectroscopy, X-ray diffraction, ultraviolet spectroscopy and scanning electron microscopy. The physicochemical properties of Ch-Ma and its film were studied in detail. The results indicated that the salt was obtained by the protonation reaction of the amino group of chitosan and maleic acid, which caused the crystallinity of chitosan decreasing and improved its solubility. Ch-Ma showed good film-forming performance when the medium pH was less than 9. The light transmittance of Ch-Ma film was above 90%. Compared with Ch-Ac film, the structure of Ch-Ma film was looser, its porosity was higher, water absorption, moisture absorption and water vapor permeability were lower, water resistance was stronger and mechanical strength was higher, which might be due to the protonation of chitosan amino group and π-π stacking interaction. The preparation method of solid Ch-Ma was easy and sanitary. Ch-Ma had good solubility and film-forming performance, which was expected to broaden the application range of chitosan derivatives.