Tilt and splay of surfactants on surfaces

The energy of a monolayer of surfactant on a surface is calculated as a function of the orientation of the surfactant tails. The structure is determined by a competition between the spacings preferred by the polar heads and nonpolar tails. As a function of the head-tail mismatch, we find a region of no molecular tilt, and one of uniform tilt. In the tilted state, solitonlike defects resembling micellar clusters are stabilized by entropy or finite-size effects.