Dependence of structural and transport properties of chitosan films on the preparation conditions and the polymer characteristics

The transport and mechanical properties of chitosan films formed from a chitosan-water-acetic acid ternary mixture by solvent evaporation and of the same compositions modified by oligo(ethylene oxide) mono- and diglycidyl ethers were studied as functions of the chitosan molecular mass and degree of deacetylation. It was shown that selectivity of the films used as membranes for the separation of water-alcohol mixtures increases with the degree of deacetylation. The flow density of the mixtures enriched with water increases with decreasing molecular mass. There is an optimum concentration of acetic acid in the casting solution, at which the selectivity reaches maximum. According to the electron microscopy and X-ray diffraction data, the modified films possess a less ordered structure compared to that of the initial chitosan. These films are insoluble in acid aqueous media. The mechanical properties of the films depend in a nonmonotonic way on the polymer characteristics and the conditions of film preparation.