DIPOLE-INDUCED ORDERING IN NEMATIC LIQUID-CRYSTALS FACT OR FICTION

Similar size and shape molecules with different electric multipoles ar e used to investigate effects of dipole and quadrupole interactions on the average orientation of solutes in nematic liquid crystals. Perman ent dipoles have a negligible influence on solute orientation. Order p arameters predicted from strong, short-range repulsive forces coupled with interactions between the solute quadrupole and the average electr ic field gradient felt by the solute [EFG] are consistent with experim ental values. Calculated [EFG]'s are the same sign and similar magnitu de to those determined previously from D-2 and HD. For the nematic mix ture 55wt% ZLI 1132 in EBBA, the contribution to solute ordering from long-range electrostatic interactions is negligible. (C) 1997 Elsevier Science B.V.