Specific features of the capillary rise of aqueous solutions of binary surfactant mixture

The effect of the composition of aqueous solutions of surfactant mixtures ( Triton X-100 and cetyltrimethylammonium bromide, CTAB) on the capillary ris e and the wetting of glass was studied. It was established that contact ang les sharply increase upon the wetting of glass by the solutions of surfacta nt mixtures during the formation of the first adsorption layer on the glass surface and markedly decrease during the formation of the second layer com pared with CTAB solutions of the same concentrations in the absence of Trit on X-100. The results obtained are explained by synergism upon the formatio n of mixed adsorption layers at the solution-glass interface. An unusual ef fect of the receding of surfactant mixture solutions from the initially wet ted surface was disclosed. This effect was observed during the capillary ri se of solutions with concentrations 10(-4)-6 x 10(-4) M. Data on the kineti cs of the reduction of the height of capillary rise were obtained, and the relaxation times of contact angles were determined.