Preparation of half-deacetylated chitosan by forced penetration and its properties

A novel rapid preparation of half-deacetylated chitosan with relatively large molecular weight was studied. Chitin from shrimp was first undergone forced penetration in vacuum and then deacetylated using concentrated NaOH with control of the reaction time. The degree of deacetylation (DD) was monitored using potentiometric titration and 1H NMR. The half-deacetylated chitosan showed a distinct change in Scanning electronic microscopy (SEM) compared to chitin material, and behaved viscous and translucent in water. They were turned into microfibrils with a diameter of around 1 μm, which facilitate near homogeneous deacetylation. After degradation by pectinase, they were soluble in aqueous solution at all pH. The results of Intrinsic viscosity, FT-IR, and powder X-ray diffraction (XRD) show that the molecular weight and DD are collectively responsible for the solubility in the condition of random deacetylation of acetyl groups, which resulted from the intermolecular force.