POLYMER POLARITY AND SURFACTANT ADSORPTION

The effect of polymer polarity on surfactant adsorption from aqueous solution is discussed. The analysis assumes that surfactant adsorption at the polymer-water interface follows a Langmuir-type adsorption isotherm and the free energy of adsorption is controlled by the interfacial tension of the interface. Saturation adsorption given by the area per molecule of surfactant at the critical micelle concentration (CMC) of the surfactant is related to the polymer-water interfacial tension and the polarity of the polymer surface, calculated from the polar and dispersion contributions to the polymer surface energy. Available data on the area per molecule of sodium lauryl sulfate on various polymer surfaces have been used to test satisfactorily the above analysis. The analysis is used to interpret some of the observations relating to surfactant adsorption encountered in the emulsion polymerization of polar monomers and particle size determination of latexes by the soap titration method. Further, potential utility of such area per molecule data to characterize the nature of polymer surfaces is also discussed.