The characterization and utilization of ammonium salt chemistry to modify the chemical and physical properties of chitosan films

A detailed literature review of chitin and chitosan as a fiber and film former is presented. Key parameters for fiber and film formation are outlined. Solvent systems and their effect on chitosan fiber and film morphology and tensile properties are included. Near Infrared Spectroscopy is introduced as a new method to determine the degree of N-acetylation in Chitin and Chitosan as well as a mixture of their monomer constituents, 2-acetamide-2-deoxy-D-glucopyranose and 2-amino-2-deoxy-D-glucopyranose. Solvent casting of chitosan is analyzed emphasizing the free amine regeneration from the ammonium salt. Alcoholic bases are found to give superior dimensional stability and processibility in films. Surfactants were screened and investigated to improve the wet tensile properties of chitosan. Amphoteric surfactants were found to plasticize films and generate hydrophobic regions within these films. The tensile properties were found superior to chitosan without surfactants and to carrageenan and collagen. Finally, the ammonium salt was used as a reaction media through solid state N-acylation to form amides. Diacids were used to also give O-acylation and crosslinks in films. The films became water insoluble after the reaction with mono- and poly-functional acids even in the ammonium salt state. Data analysis was performed using FTIR, DSC, X-ray, UV-VIS, NIR, and Instron Tensile Testing.