Ksenija Kogej and Jože Škerjanc
Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
The effect of cationic surfactant cetylpyridinium chloride, CPC, on hydrodynamic behavior of sodium poly(styrenesulfonate), NaPSS, and sodium poly(acrylate), NaPA, was investigated and compared to the effect of simple salt, NaCl. It was found that the surfactant causes a larger reduction of the viscosity of polyelectrolyte solution than does NaCl. The difference is ascribed to the fact that, in addition to the electrostatic effects in the change of the polymer coil shape, the polymer-induced surfactant micelle causes additional coiling of the polyion chain around itself. The effects are greater in NaPA than in NaPSS solutions. In addition, the mean apparent molar volume change, DFV, is bigger in the presence of NaPA than NaPSS, respectively. Possible reasons for these differences are the more flexible PA- chain relative to the PSS- chain, the specific interaction between surfactant micelle and benzenesulfonate ring of NaPSS monomer units, and bigger surfactant micelles in the case NaPA.