A Study of the Viscosity Characteristics of Chitosan Solutions in the Presence of Organic Cosolvents

Resumo

The effect of organic cosolvents (ethanol and isopropanol) on the viscosity characteristics of acetic acid aqueous solutions of chitosan is studied. Sorption and deformation–strength properties, as well as resistance to the process of enzymatic degradation of materials obtained from solutions, are determined. It is shown that the introduction of cosolvents into the chitosan–1% acetic acid system is accompanied by a consistent decrease in the intrinsic viscosity of polymers. It is found that, in the presence of cosolvents, at concentrations below the crossover concentration, chitosan molecules exist as systems of interacting (aggregated) macromolecules rather than isolated macromolecular coils. A change in the conformation of chitosan and the type of macromolecular aggregates in acetic acid solutions in the presence of cosolvents leads to a number of consequences: polymer units become less accessible to an enzyme preparation, the rate of enzymatic degradation decreases, and mechanical characteristics of film materials change.