Synthesis of High Molecular Weight Chitosan from Chitin by Mechanochemistry and Aging

We report herein a novel path, relying on a combination of mechanochemitry and aging, to afford high molecular weight chitosan with minimal use of energy and solvent. We demonstrate that this method is versatile and applicable to a number of chitin sources, including crude crustaceans and insect shells, yielding deacetylation up to 98% and molecular weights up to 20,770 kDa. Chitin deacetylation yields were measured by magic angle spinning nuclear magnetic resonance. Chitin and chitosans molecular weights were calculated by viscometry using an ionic liquid as a solvent. The effect of amorphization of chitin, and aging conditions, including humidity levels and temperatures were studied.