The interaction of amylopectin with cetylpyridinium chloride

Abstract

The complex which is formed between amylopectin and cetylpyridinium chloride (CPC) in dilute aqueous NaOH is indicated by a turbidity, measured spectrophotometrically. No significant turbidity is apparent in the absence of any of the components. Aggregation of the complex is dependent on the relative concentrations of polysaccharide and surfactant and the absolute concentration of NaOH. A simple analytical expression relating these concentrations is derived from the experimental data, on the basis of which accurate qualitative and quantitative predictions are made and verified. On the basis of the suggestion that the active form of the surfactant is the micelle, the critical micelle concentration of CPC is calculated as a function of electrolyte concentration. Within experimental error, agreement is obtained with recent literature values. The aggregated complex is pictured as consisting of a matrix of negatively charged amylopectin molecules, cross-linked by positively charged CPC micelles.