Controlled Chitosan Molecular Weight Reduction by Mechanochemical and Aging-based Phosphoric Acid Hydrolysis

Chitosan is typically produced by the deacetylation of biopolymer chitin. Its molecular weight (Mw) is a function of the chitin source and the deacetylation conditions. It remains a challenge to both control the Mw of chitosan and obtain good polydispersity, essential for optimal function of chitosan in different applications. This study explores the use of mechanochemistry and aging as effective methods towards the controlled reduction of the Mw of commercial high Mw chitosan (HMwChs) with phosphoric acid where Mw was measured by gel permeation chromatography (GPC). In comparison to conventional solution-based methods, this new mechanochemical process features improved process mass intensity in comparison to conventional techniques and affords low Mw chitosan (LMwChs) samples in a range of 200 to as low as 19.5 kDa, with a polydispersity of 1.8.