Polymer-Surfactant Interactions by Surfactant Selective Electrodes

Abstract

The interaction between ionic surfactants and several polymers was investigated using surfactant ion and counterion selective electrodes. Four block polypeptides containing either alanine-lysine or alanine-glutamic acid were observed to bind a number of oppositely charged surfactant ions, dodecyl sulfate and dodecyltrimethylammonium ions, respectively. The binding ratios, corresponding to the net charge on the peptides, were similar to those found previously using titration calorimetry. Also studied were polyvinylpyrrolidone, which exhibited complex dodecyl sulfate binding, and cytochrome c peroxidase. The later strongly bound a number of dodecyl sulfate ions which was also approximately equal to the number of basic amino acid residues present in the protein. All six polymers reduced the critical micelle concentration from its value in the absence of the polymers whenever appreciable surfactant binding occurred.