Aging of solutions of chitosan varying in degree of acetylation (DA) and degree of dissociation (a) was studied using two techniques. The first concerned potentiometric experiments performed during 3 days on solutions having the same concentration of amino groups (5.2% < DA < 0.6% and 0 < alpha < 1.1). The presence of aggregates at low cc certainly depends on electrostatic interactions for low DA values and on hydrophobic interactions and H-bondings for high values. When a. increases, the role of the cationicity of the amine groups, which depends on DA, seems to play a more important role on the behavior of the polymer chains. The second regarded capillary viscometric experiments performed during 5 days on solutions of the same polymer concentration (5.2% < DA < 70.6% and 0 < alpha < 0.30). The observations mentioned above and the results obtained in a previous paper (Biomacromolecules 2001, 2 (3), 765) are confirmed, and the influence of the electroviscous effects is discussed.
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