Adsorption Pattern of Mixtures of Trimethylammonium-Modified Hydroxyethylcellulose and Sodium Dodecyl Sulfate at Solid-Liquid Interfaces

Abstract

We studied mixts. of aq. solns. of cationic hydroxyethylcellulose JR 400 polymer and anionic sodium dodecyl sulfate using dynamic light scattering and at. force microscopy (AFM). A ternary phase diagram was established showing three interesting realms of the polymer-surfactant-water mixt.: a prepptn. area of lowered viscosity (polymer excess) compared to the pure polymer soln., a postpptn. area (resolubilization at surfactant excess), and highly dild. samples with a stoichiometrical surfactant-polymer ratio close to that of max. pptn. Samples with various compns. representing these areas were imaged by at. force microscopy on mica and on hydrophobically modified silica in contact mode. A correlation between light scattering data concerning particle size and, more important, structuring in the bulk on one hand and AFM images on the other hand was obsd. It was revealed that the influence of surface properties is of less importance for adsorption, compared to the influence of the mixt. in the bulk, provided that the mixt. is prepd. prior to adsorption.