ИСТИНА

The present work is devoted to the study of chitosan and hydrophobically modified (HM) chitosan multichain clusters in dilute aqueous solutions. Clusters were observed by light scattering and transmission electron microscopy (TEM). It was demonstrated that the size of clusters and their aggregation numbers increase at the introduction of hydrophobic side groups into polymer chains. The key result concerns the effect of the chain length of individual macromolecules on the aggregation behavior. It was shown that both for unmodified and HM chitosan the size of clusters is independent of the length of single chains, which may result from the electrostatic nature of the stabilization of clusters. At the same time, the number of macromolecules in one cluster increases significantly with decreasing length of single chains in order to provide a sufficient amount of associating groups to stabilize the cluster. The analysis of the light scattering data together with TEM results suggests that the clusters of chitosan and HM chitosan represent spherical nanogels with denser core and looser shell covered with dangling chains.