Effect of the ionic strength of the media on the aggregation behaviors of high molecule weight chitosan

Abstract

The objectives of this study are to explore the effect of the ionic strength of aqueous acidic media and the intrinsic characteristics of chitosan used on the formation of different types of aggregation. Two different degrees of acetylation (DA) of β-chitosan are prepared from β-chitin by stepwise alkali deacetylation. These two chitosans have high chain stiffness and typical good solvent behavior in a 0.20 M acetic acid/0.10 M sodium acetate buffer solution. However, a trace amount of aggregates forms in the higher DA chitosan dilute solution. At ionic strength (I) ≥ 0.20 M, the association of compact chitosan forms and/or the amount of the aggregates increases with increasing I of the media. At I = 0.01 M, a considerable quantity of particle structure is observed in the low ionic strength solution and the electrodynamic coupling effect predominates on the mobile behavior of the extended and congested chitosan molecule in solution.