AMPHIPHILIC LANGMUIR-BLODGETT-FILMS AS A NEW TOOL FOR INDUCING ALIGNMENT TRANSITION IN NEMATICS

Mono- or multilayers of egg lecithin, distearoylphosphatidylcholine le cithin (DSPC-L), dimiristoyl-phosphatidylcholine lecithin (DMPC-L) and stearic acid (SA) deposited by Langmuir-Blodgett technique were used as aligning films in a nematic liquid crystal cell for obtaining a uni form homeotropic orientation and a temperature driven surface transiti on close to the clearing point. An excellent homeotropic alignment of the liquid crystal was obtained when a monolayer of DMPC-L, DSPC-L or SA was used. In these cases, a sharp and reversible transition from th e homeotropic orientation to a set of circular domains, where the liqu id crystal molecules have a degenerate quasi-planar alignment, was obs erved a few tenths of a degree below the nematic-isotropic phase trans ition.