Chitosan gels: 1. Study of reaction variables

A study has been made of the gelation behaviour of chitosan solutions on reaction with acyl anhydrides. The effect on the time to onset of gelation of varying the nature and concentration of the acyl anhydride, the chitosan concentration, the temperature, and the nature of the cosolvent has been examined. The results indicate that gelation occurs because of decreased solubility of the polymer molecules due to the increased extent of $\text{N-}\text{acylation}$, and that variations of the above parameters influence the rate of gelation through influencing the rate of $\text{N-}\text{acylation}$. The syneresis of the gels produced has been briefly examined.