Chitosan structure in aqueous solution

Chitosans having three different degrees of acetylation (DA) were studied in acid solution using the uranyl staining technique and electron microscopy. Strings of approximately spherical aggregates were seen. The aggregates were interpreted as micelle-like agglomerates formed by almost fully acetylated polysaccharide, interconnected by blocks of almost fully deacetylated polysaccharide stretched by electrostatic repulsion. These agglomerates include NH3+ groups which produce electrostatic swelling of the agglomerates, giving a radius proportional to the degree of deacetylation. The length of the strings are also proportional to the deacetylation degree. These strings are extended because of the electrostatic repulsion between charged ammonium groups.