Vesicles prepared with synthetic amphiphiles (dioctadecyldimethylammonium bromide and chloride, dihexadecyl phosphate
and its sodium salt) were obtained by sonication, ethanol injections, and chloroform injections. The hydrodynamic diameter
of vesicles (Z)h), estimated from the diffusivity measured by quasielastic light scattering, ranged from 230 to 3000 . The
electrophoretic mobility (£/m) was measured by free-flow electrophoresis. The zeta potential ({) and the degree of counterion
dissociation (a) of the vesicles were calculated from Um and conductivity data, a decreased with increasing Dh of the vesicles,
probably due to the decreasing headgroup area and the increasing counterion association needed to relax the surface electrostatic
potential. The electrophoretic mobility was also calculated (Uc) according to an impenetrable, nonconducting sphere model
with a spherically symmetric charge distribution approximation. Within the limits of the experimental error(s) of the (different)
methods employed and the assumptions made in the calculations, the fact that the t/m/t/c ratio ranged from 1.3 to 7.5 was
considered to be a good agreement between the calculated and the experimental values.