Determinations of surface tension (gamma) at the air-water interface, contact angles (0), and in and ex situ ellipsometric mean small vesicles and spin-coated polystyrene sulfate (PSS) films on silicon wafers. Upon the addition of NaCl (50 mM final concentration) to a 0.2 mM DODAB dispersion, adsorption from vesicles on PSS films immediatly yielded a DODAB adsorption monotonically increased reaching at most 1.6-1.8 nm as a function of time (from 15 min of interaction), which were not values consistent with bilayer deposition. At early stages in pure water, DODAB adsorption linearly increased with the square root of time, indicating a vesicle diffusion controlled process with ca. 1.0 x 10(-11)m(2) s(-1) as the vesicle diffusion coeficient (D) in nice agreement with reported D for similar vesicles. In contrast, adding 50 mM salt, resulted in a very fast adsorption kinetics determined by the hydrophobic attraction between salt-induced defects on the bilayer and the film surface. Ex situ measurements of DODAB adsorption were difficult because wetting/drying cycles of the PSS film increased its mean thickness. From 0.1 up to 1.0 mM DODAB, the adsorbed DODAB film in air was more hydrophobic (advancing contact angle, theta(a), = 84 +/- 3degrees) than the bare PSS film (theta(a) = 71 +/- 4). Air-water surface tension for a DODAB dispersion in pure water rapidly decreased upon salt addition (750 mM NaCl), suggesting salt-induced vesicle fusion with the air-water interface occurred, in nice agreement with salt-induced vesicle fusion at the hydrophobic polymer-water surface.