We have performed molecular dynamics simulations of sodium dodecyl sulfate (SDS) and a model cation at the water-CCl4 interface at a coverage of 45 Angstrom(2)/molecule. In order to isolate the effects due to the polarity of the surfactant, the model potential for the cationic surfactant is chosen to be identical to that of SDS except that the sign of all atomic charges, including counterions, are reversed. We show that the structural features of the two types of surfactant monolayers give rise to large differences in the surface potential profiles and in the overall potential difference across the water-surfactant-CCl4 interface. In addition, we show that water in intimate contact with the ionic layer is significantly altered in terms of its dynamic al properties-a decrease of up to 1 order of magnitude in the rotational correlation time for the water dipole reorientation is observed. We also show that water orientational polarization propagates well into the bulk region and that this polarization depends on the sign of the ionic surfactant.