A joint program of research in chiral/polar liquid crystals showing fast analog electrooptics is proposed between experimental and computer simulation group at the University of Colorado, Boulder, experimental groups at Chalmers University of Technology, Sweden, the University of Stuttgart, Germany and Queen's University, Canada, and the theoretical group at the University of Strathclyde, UK. While various combinations of the partners have been collaborating separately over the past several years, all with joint publications, the proposed Network will create a uniquely powerful team for forefront research on chiral liquid crystals. The proposal is focused into synthesis, characterization and theoretical modelling of novel smectic liquid crystal materials, which will have a number of advantages over the existing materials including much faster switching, lower energy consumption and a broader range of applications in electrooptic and all optical devices. A number of exotic chiral smectic liquid crystal materials will be investigated including the V-shaped switching ferroelectric smectics with the most rapid analog liquid crystal electro-optic effects; the deVries materials which tilt without layer contraction in the Smectic C* phase, the closely related orthoconic high-tilt antiferroelectrics; and the recently discovered family of bent-core liquid crystals with a polar smectic A phase that give phase-only electrooptic modulation The de Vries type smectic materials are characterized by anomalously weak layer contraction which enables one to avoid buckling of smectic layers at the tilting transition leading to the formation of the so-called zig-zag defects which seriously degrade the optical quality of smectic materials.. All of these smectic materials will be studied experimentally using polarized microscopy, polarization and tilt angle measurements, x-ray scattering technique and refractometry, and new materials with advanced characteristics will be synthesized using guidance from experiment, molecular theory and atomistic computer simulations. The proposed research highlights fundamental studies of the relationships of the properties of these novel liquid crystal systems with ramifications for a variety of areas in soft materials science. The corresponding materials development will enable a variety of novelapplications, including holographic data storage and projection, beam steering, and chirality detection. The theoretical part of the whole proposal (Work package Strathclyde) is focused into the development of the advance molecular theory of de Vries type ferroelectric materials, taking into account short-range orientational and positional intermolecular correlations, and interpretation of the experimental results obtained by other teams. Using the results of experimental studies and computer simulations, molecular models of analog de Vries smectic materials with nano-segregating groups will be developed, order parameters of these materials will be calculated numerically and compared with experimental data. Effect of various molecular model parameters on the value and temperature variation of the spontaneous polarization in de Vries type materials will be investigated including the effects of molecular shape and flexibility, dipole distribution and nano-segregating groups.
We have developed a unified molecular theory of phase transitions between different liquid crystal phases and explained the properties of the so called de Vries smectics, i.e. smectic liquid crystals that tilt without layer contraction. We have also developed a theory of dipole-dipole interactions and correlations in polar liquid crystals composed of bent core molecules.
|Effective start/end date||1/10/10 → 30/09/13|
- EPSRC (Engineering and Physical Sciences Research Council): £169,686.00
x ray scattering