Gelation in solutions of low deacetylated chitosan initiated by high shear stresses

A new process of mechanically initiated formation of chitosan physical hydrogels in aqueous solution, without a cross-linking agent, was studied. Physical hydrogel is formed by mechanical activation of solutions of chitosan with a low deacetylation degree (58%) in situ in a rotor-stator device for 10 s. The formation of 3D gel structure has been proven by rotational viscometry and dynamic rheometry methods. Gelation is caused by the action of high shear stresses initiating the formation of hydrophobic associates from residual chitinous blocks. In comparison with the films from untreated chitosan, the films obtained by drying hydrogel have a lower degree of crystallinity and a higher sorption capacity towards water vapor and Cu²⁺ ions, as well as the ability to retain up to 5000% of water during re-swelling without destruction.