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This review highlights research topics like chiral phases (cholesterics, blue phases and polar phases), structural variations of the mesogens (kinked mesogens, polyphilic mesogens) and various aspects of liquid crystalline polymers. It closes by describing recent aspects like LC-materials from renewable resources, experiments in the ISS and ferroelectric nematic phases. [ABSTRACT FROM AUTHOR]

Chiral phases in a system of biaxial molecules are investigated based on a theory of biaxial liquid crystals, which we have presented in past work. Four chiral phases are identified, corresponding to a uniaxial nematic phase, two biaxial nematic phases, and a discotic phase, respectively. We find that in the chiral uniaxial nematic phase, the pitch of the chiral structures does not depend on temperature. In contrast, in the two chiral biaxial nematic phases, as well as in the chiral discotic phase, the pitch is temperature-dependent. [ABSTRACT FROM AUTHOR]

Abstract: Various deuterium one- and two-dimensional (2D) NMR techniques are used in the present study to characterize molecular self-diffusive processes in some novel mesophases. Both aligned and powder samples of liquid crystals (LC) are chosen to investigate rotational and/or translational jump diffusions. It is demonstrated that rotation of aligned LC samples in a NMR goniometer probe can be helpful in obtaining dynamic and structural information. Both spectral simulations and/or pulse separation (τ) dependences of the quadrupole echo intensity are successfully employed. Deuteron spin-lattice relaxation times and angle dependent spectra are measured in a columnar phase of a monomeric discotogen to illustrate both the fast and intermediate motion regimes. Jump diffusions of chiral rodlike molecules in various smectic C⁎ (SmC⁎) phases and twist grain boundary A⁎ (TGBA⁎) phase are studied. In the LC 10B1M7, the jump rate (or diffusion constant) is determined as a function of temperature in the ferro-, ferri- and antiferro-electric chiral C⁎ phases. 2D deuterium exchange NMR is used to monitor the dynamic processes (self-diffusion) in the ferroelectric SmC⁎ and TGBA⁎ phases. Moreover, packing information of the phase can also be obtained in the two ferrielectric subphases and TGBA⁎ phase, which can be compared with results obtained by X-rays measurements. [Copyright &y& Elsevier]

Dielectric measurements have been carried out on the chiral smectic Cα (SmCα*) phase of a MHPOBC analogous compound. Two relaxation modes have been observed in this phase for planar orientation of the molecules. One process has been observed at frequency lower than that of the soft mode of the chiral smectic A (SmA*) phase. This relaxation process is connected with the helicity of the SmCα* phase. In the high-frequency region, another relaxation process has been observed in the SmCα* phase for which bias field dependence is similar to that of the soft mode at the SmA*-SmC* phase transition. The experimental observations are in agreement with a recently proposed dielectric theory for the SmCα* phase and theoretical dielectric results obtained by numerical simulations. Thus, we report here experimental verification of two theoretically predicted dielectric modes in the SmCα* phase. [ABSTRACT FROM AUTHOR]

Abstract: There are only few antiferroelectric liquid crystal (AFLC) materials, which have shown long temperature range Sm phase near room temperature. One such material is chlorinated version of MHPOBC. In the present work we are reporting dielectric spectroscopy of this material over a frequency range of 1Hz to 10MHz for planar and homeotropic anchoring geometry of sample molecules. In the antiferroelectric Sm phase, two relaxation processes have been observed under planar anchoring condition of molecules. These two dielectric processes are reported and discussed as a function of temperature, bias electric field and thickness of the sample. [Copyright &y& Elsevier]