A COMPARATIVE-STUDY ON THE ADSORPTION OF TRITON-X-100 AND TWEEN-20 ONTO LATEXES WITH DIFFERENT INTERFACIAL PROPERTIES

In this paper we have studied the adsorption of two nonionic surfactan ts, Triton X-100 and Tween 20 (polyoxyethylene (20) sorbitan monolaura te) onto latexes with different interfacial properties. Four different samples of polystyrene beads were used in this study. A hydrophobic s ample was prepared by conventional emulsion polymerization of styrene. Hydrophilic polymer colloids were prepared by the emulsifier-free emu lsion copolymerization of styrene and 2-hydroxyethylmethacrylate in di fferent proportions and acrylic acid. In all cases potassium persulfat e was used as initiator. In order to consider the mechanism of the ads orption at the different liquid-solid interfaces, adsorption isotherms under different pH and ionic strength conditions were performed. Elec trokinetic characterization and colloidal stability of bare hydrophobi c and hydrophilic latexes and the surfactant-latex complexes were comp ared to understand the effect of the nonionic surfactant on the electr ic double layer structure. The results showed that Tween 20 and Triton X-100 are adsorbed in the same way on surfaces with different polarit y but in different amounts. Hydrophobic interaction is the main drivin g force in the adsorption. The effect of the adsorption on the electro kinetic properties and stability of the latexes was found to be differ ent for hydrophobic and hydrophilic latexes as a consequence of the di ssimilar interfacial properties of these two latex samples. (C) 1997 A cademic Press.