Reversible macroscopic dynamics of polar nematic liquid crystals: reversible currents and their experimental consequences.

Polar liquid crystalline phases are relevant for fluid liquid crystal phases observed in banana liquid crystals as well as for a class of polymeric liquid crystalline materials investigated recently. In this Brief Report we present the reversible dynamics for polar nematic liquid crystals with C_{infinityv} symmetry, where the macroscopic polarization representing polar order acts as an independent macroscopic variable. We find reversible coupling terms, for example, between flow and temperature and concentration gradients specific for the existence of a polar preferred direction.

Splay-bend textures involving tetrahedratic order.

We show that defect-free splay-bend textures are less energetic compared to uniform states in liquid-crystalline phases that possess both quadrupolar (nematic) and octupolar (tetrahedratic) order. This is because, in such systems, there is a symmetry-allowed linear gradient term in the energy. Another unusual feature of these splay-bend textures is the fact that they have a non-homogeneous, space-dependent free-energy density.

Low-voltage-driven electromechanical effects of swollen liquid-crystal elastomers.

We experimentally investigate, in detail, electromechanical effects in liquid-crystal elastomers (LCEs) previously swollen with low-molecular-weight liquid crystals (LMWLCs). Both polydomain (POLY) and monodomain (MONO) LCEs were studied. We used a well known LMWLC, 4-n-pentyl-4-cyanobiphenyl (5CB) as a solvent.

Deformable tetrahedratic phases: the effects of external fields and flows.

We discuss changes in the symmetry and physical properties of an isotropic phase which has initially tetrahedral symmetry characterized by four unit vectors. In its undeformed state, these four vectors are at the tetrahedral angle (109.47 degrees) to each other.

Swelling dynamics of liquid crystal elastomers swollen with low molecular weight liquid crystals.

We experimentally investigated the swelling behavior of thin films (approximately 150 microm) of liquid crystalline elastomers (LCEs) by low molecular weight liquid crystals (LMWLCs). The two LMWLCs used are the well-known nematic liquid crystals, 4-n-pentyl-4-cyanobiphenyl, and 4-methoxy-benzilidene-4-butyl-aniline. Both polydomain (POLY) and monodomain (MONO) LCE swelling are studied.