Chitosan-cellulose sulfate acetate complexation in acetic acid solutions

Colloidal and optical properties of dispersions of chitosan-cellulose sulfate acetate interpolyelectrolyte complexes resultant from mixing dilute solutions of the polymers in acetic acid and in acetic acid-based buffer mixtures are investigated. It is established that, in acetic acid, an insoluble complex is formed whose composition corresponds to the unit ratio [chitosan]: [cellulose sulfate acetate] = 1: 1.5, mol/mol. Particle size and concentration are independent of the order of mixing of the solutions of the polymers. In buffer solvents, the particle size is larger and the particle concentration is lower than those in acetic acid. Excess chitosan causes the dissolution of the complex. The addition of low-molecular-weight electrolytes to ionic strengths of 0.2-0.3 also promotes the dissolution of the interpolyelectrolyte complex. The complex becomes completely soluble at ionic strengths of 1.5-2.0.