SOLUBILIZATION OF A RIGID POLYSACCHARIDE - CONTROLLED PARTIAL N-ACETYLATION OF CHITOSAN TO DEVELOP SOLUBILITY

The solubility-structure relationship was studied in the acetylation of chitosan to elucidate key factors for solubilization of rigid polysaccharides. N-Acetylation of chitosan proceeded smoothly and reproducibly in a highly swollen state, and the degree of substitution was easily controlled. Evaluation of the properties of the resulting acetylated chitosans indicated the importance of the distribution mode of acetyl groups as well as the extent of substitution for solubilization. The chitosan derivatives with about 50% substitution prepared under appropriate conditions exhibited high solubility in water, and the presence of half a molar amount of randomly distributed substituents on the amino groups was confirmed to be an essential requirement in developing solubility. The present procedure is much simpler to prepare the water-soluble chitin than the conventional method involving partial deacetylation of chitin.