Preparation and Physico-Chemical Characteristics of N-Maleoyl Chitosan Films

N-Maleoyl chitosan (N-MC), a water-soluble derivative of chitosan, was synthesized by N-carboxyacylation of chitosan and maleic anhydride. N-MC films were prepared by solvent casting and kept in a desiccator for different time intervals in order to obtain N-MC films with different degrees of cross-linking. The swelling characteristic of N-MC films was investigated. When the ageing time increased from 5 to 30 d, the swelling of the N-MC films decreased from ∼475 to ∼160% and the weight loss decreased from ∼25 to ∼8%, corresponding to the increase in the cross-linking density from 0.86 × 10⁻⁶ to 8.97 × 10⁻⁶ mol · cm⁻³. Additionally, the swelling behavior of the N-MC films was influenced by changes in either the pH or the ionic strength of the media.