Langmuir, Vol.11, No.8, 2938-2943, 1995
Interactions Between Dioctadecyldimethylammonium Chloride or Bromide Bilayers in Water
Interactions between dioctadecyldimethylammonium bromide (DODAB) or chloride (DODAC) closed bilayers in water are investigated. First, bilayers from vesicles are deposited onto oppositely charged polystyrene microspheres. Thereafter, a further increase in amphiphile concentration leads to vesicle adhesion to the bilayer-covered latex. For DODAC vesicles, the extent of vesicle adhesion to the covered latex is much higher than for DODAB vesicles. There is no rupture of adhered DODAC vesicles. In contrast, adhesion of DODAB vesicles is followed by vesicle rupture. Rupture for DODAB is associated with the absence of hydration repulsion whereas the absence of rupture for DODAC is related to its occurrence. A high extent of interdigitation in the DODAC bilayer causes the long-ranged hydrophobic attraction responsible for adhesion and can be associated with a long-ranged hydrophobic attraction between bilayers. The possibility of adhesion at a secondary minimum is ruled out for interactions in water.
Keywords:CHARGED SPHERIC VESICLES;OSMOTIC-STRESS MEASUREMENTS;POLYSTYRENE MICROSPHERES;AMPHIPHILE VESICLES;AMMONIUM ACETATE;DLVO ACCOUNT;SURFACTANTS;MONOLAYERS;ADSORPTION;FORCES