An Efficient Method for Chitin Processing Using Phosphoric Acid: Oligomers, Nanocrystals, and High Polymers

Chitin is the second most abundant biopolymer on Earth behind cellulose. It is an important component in the shells of shrimp and crabs, the cell walls of fungi, etc. Chitin processing has remained challenging due to its poor solubility in common solvents, which greatly limits its utilization. We report using phosphoric acid as a versatile medium for chitin processing. With a precise control of the kinetics of two competitive processes, namely physical dissolution and acid hydrolysis, three types of products can be produced from chitin: water-soluble oligomers, nanowhiskers, and high molecular weight polymers. Properties of these products, which include the degree of deacetylation, surface charge, molecular weight and polydispersity, etc., were characterized. Potential applications of these materials in areas such as agriculture, food science, and polymer engineering are discussed.