ADSORPTION OF DIOCTADECYLDIMETHYLAMMONIUM CHLORIDE ON SILICA

Adsorption of dioctadecyldimethylammonium chloride (DODAC) on silica from its vesicle in aqueous solution has been studied. The adsorption isotherm indicates that the interaction between DODAC and silica is strong because of the electrostatic attraction force and that a patch-like bilayer is probably formed. Fluorescence and ESR probe measurements show that the micropolarity of the DODAC adsorbed layer on silica is lower, but its microviscosity is higher, compared to those of the DODAC vesicle in aqueous solution. Further, Yellow OB, a water-insoluble dye, is incorporated in the DODAC adsorbed layer indicating its hydrophobic nature; the incorporated Yellow OB is barely removed by washing with deionized water.