INDUCTION OF TILTED CHOLESTERIC STRUCTURES IN MICROCONFINED LIQUID-CRYSTALS

C-13-NMR measurements of the chiral mesogen cholesteryl-undecylcarbona te (CHUC) adsorbed in Anopore membranes with cylindrical pores of 0.2 mu m diameter are presented. The pitch of CHUC in the cholesteric phas e is of order of the pore diameter, and in view of the planar axial an choring a strong in fluence of the walls on the director field can be expected. Simulation of the angular dependence of C-13-NMR line shape allows to determine a mean tilt angle of 60 degrees of the director wi th respect to the helical axes which are oriented along the channels. Furthermore, at T=341K a correlation time of 130 mu s for reorientatio nal motions could be obtained which is connected with molecular diffus ion along the pores. Optical and NMR-measurements are compatible with a tilted helical director field for the cholesteric LC material within the pores.