Dynamic light scattering in semidilute and concentrated chitosan solutions

Dynamic light scattering was used to monitor relaxation processes in chitosan solutions at concentrations within the semidilute and concentrated regimes, Kohlrausch–Williams–Watts (KWW) equation being successfully fitted to intensity correlation function data. The dependence of KWW equation parameters on chitosan concentration indicated that an increase in concentration from semidilute to concentrated regime resulted in distribution of relaxation rate narrowing; temperature dependence of average relaxation rate indicated that relaxation was an energy activated process, whose parameters were associated to the interaction between chitosan chains (enthalpy of activation) and rigidity of chitosan conformations (pre-exponential factor).

Scheme representing an entanglement between two chitosan macromolecular coils, favored by the hydrophobic effect.Figure optionsDownload as PowerPoint slideHighlights
► Dynamic light scattering was used to probe relaxation phenomena in chitosan solutions.
► Correlation functions were well described using stretched exponentials.
► Increase in relaxation rate distribution width implied concentrated regime occurrence.
► Hydrophobic effect influences physical crosslinking.
► Average relaxation rate follows an Arrhenius-type dependence.