[Comparative study of the physico-chemical properties of chitosans with varying degree of polymerization in neutral aqueous solutions].

The physicochemical properties of chitosan samples with high (130 kD) and low (30 kD) molecular masses in neutral aqueous solutions (pH 6.0) were studied by the methods of high-speed and equilibrium sedimentation, viscosimetry, and NMR and UV spectroscopies. Differences in the hydrodynamic characteristics of the samples were revealed. It was found that low-molecular-weight chitosan represents flexible linear macromolecules which undergo conformational changes upon temperature increase. The high-molecular-weight chitosan forms more rigid asymmetric structures whose conformation does not vary significantly with temperature increase. It was found that the high-molecular-weight chitosan has a higher constant of binding to the anionic dye tropeoline 000-II, which can be explained by different conformations of their macromolecules in solution.