  We investigate the structure formation of amphiphilic molecules at planar
walls using density functional theory. The molecules are modeled as (hard)
spheres composed of a hydrophilic and hydrophobic part. The orientation of the
resulting Janus-particles is described as a vector representing an internal
degree of freedom. Our density functional approach involves Fundamental Measure
Theory combined with a mean-field approximation for the anisotropic
interaction. Considering neutral, hydrophilic and hydrophobic walls, we study
the adsorption of the particles, focussing on the competition between the
surface field and interact ion-induced ordering phenomena. Finally, we consider
systems confined between two planar walls. It is shown that the anisotropic
Janus interaction yields pronounced frustration effects at low temperatures.
