SMECTIC LAYER TRANSITIONS AT THE SURFACE OF AN ISOTROPIC LIQUID

A density-functional theory of the interface between a liquid crystal and a wall predicts a first-order wetting transition by the smectic-A phase when the bulk liquid is isotropic. This is preceded by a prewett ing transition away from bulk coexistence. The incomplete and complete wetting regimes are accompanied by a finite and an infinite number of layer transitions, respectively. The layering mechanism shows that th e transitions can disappear both very near and far from the isotropic- nematic-smectic-A triple point. These results reconcile findings from previous theories and experiments.