2002, Berth, Gisela, Cölfen, Helmut, Dautzenberg, Herbert

Static and dynamic light scattering as well as analytical ultracentrifugation and viscosity measurements were used to investigate the chain conformation of chitosans in salt-containing solutions (pH 4.5; ionic strength about 0.12 M). The samples of various degrees of acetylation were chemically homogeneous. The molecular-weight dependence of the radius of gyration has given clear evidence for a relatively flexible wormlike chain with a persistence length of about 6 nm irrespective of the degree of acetylation, where excluded-volume effects and the polydispersity of the samples were taken into account. In contrast, the interpretation of the hydrodynamic data via a “whole-body approach” according to the Wales-van Holde ratio suggested a strongly elongated chain conformation. The failure of the latter to properly reflect the chain conformation was ascribed to the high extent of draining. A nearly free-draining case can also account for the high scaling exponent of the relationship between intrinsic viscosity and molecular mass.