Gelation behavior with acetylation of chitosan for membrane preparation

The aim of this work is to investigate the gelation behavior of chitosans which has various degree of acetylation (DA) of amino group to ensure the preparation of the designed membrane structure. The DA was controlled by the amount of acetic anhydride added to the solution of chitosan/acidified water/methanol mixture. The gelation behavior was evaluated by the gelation time and the quantity of syneresis. The mechanical strength of acetylated chitosan gels was also measured. The optimum condition for the formation of the membrane, i.e. chitosan concentration, acetic acid/ chitosan mass ratio, methanol/water mass ratio, and amount of acetic anhydride for acetylation, was determined. This composition gives low contractility, shorter gelation time, and high mechanical strength to the membrane and the gel. Useful information not only for a preparation of a membrane but also for an immobilized carrier or a chemical reaction system was obtained in this work.