SURFACE-FIELD INDUCED ORGANIZATION AT SOLID FLUID INTERFACES/

Self-assembled monolayers of alkanethiol derivatives have been used to control the anchoring of nematic films of alkylcyanobiphenyl (nCB) li quid crystals. Variation of the surface field, via the omega-functiona l group presented at the liquid crystal interface, has allowed us to e xplore both orientational wetting and anchoring transitions. It is fou nd that low-energy CF, surfaces give rise to homeotropic anchoring of 8CB whilst CO2H and OH terminated surfaces yield planar anchoring. The anchoring transition lies close to 5CB on CF3- and 8CB on CH3-termina ted surfaces. The molecular alignment in the interfacial region is stu died using a modified evanescent wave ellipsometric approach in which the position of the Brewster angle represents our integrated order par ameter. We find complete orientational wetting by homeotropic nematic films at the substrate/isotropic fluid interface, for sufficiently low energy surfaces. In contrast, in our systems, planar anchoring is not associated with orientational wetting.