A new series of organosiloxane ferroelectric liquid crystalline materials have been synthesized, and their mesomorphic and physical properties have been characterized. The new series contains a siloxy chain attached to the hydrocarbon chain at the nonchiral end of the molecule. All materials show a very low melting point ('5 "C) and exhibit chiral smectic A (SmA) and chiral smectic C (SmC*) mesophases. The changes in the siloxy chain length strongly affect the mesomorphic behavior and electrooptic properties of these materials. Increasing the number of siloxy units in the chain increases the temperature range of the SmA phase, with a concomitment decrease in the SmA-SmC* transition temperature. The electroclinic effect in the smectic A phase is characterized by a large electroclinic coefficient (-4 "V-l pm-l at T-TAc* = 2 "C) and low switching time (<40 ps). One of the materials shows one of the highest value of spontaneous polarization P, ever reported in the SmC* phase for similar siloxane materials with P, = 342 nC cm-2 at 25 "C.

A new method has been developed to determine the surface anchoring strength W and the tilt θt of the nematic director from the normal to a curved nematic–air interface. This method is based on the comparison of interference textures obtained by polarization microscopy experiments to numerical simulations of nematic liquid crystals within partially filled cylindrical tubes enforcing homeotropic anchoring. For the nematic liquid-crystal mixture ZLI 2860, we obtain θt=7°±1°, W=(1.5±0.5)×10−6 J/m2 at the nematic–tube and W&gt;10−5 J/m2 at the nematic–air interface.

Mesoscale three-dimensional lattices are formed in polymer-dispersed liquid crystals using one-step holographic fabrication. Nematic liquid crystal domains are patterned within a rigid polymer binder through an irradiance-driven diffusion and phase-separation process, forming a low index-contrast photonic crystals whose dielectric profile mimics the irradiance profile applied during formation. Electric fields are used to align the liquid crystal domains, allowing electrical control of the coherent scattering from these lattices. Here we present a diamond-like face centered-cubic-lattice (fcc), highlighting the several advantages over the simple fcc counterpart, including easier processing, operation in the near infrared, and deeper stopbands.

The correlation between molecular structure and electrooptic performance is studied for two series of ferroelectric liquid crystalline materials. The first series (Series 1) consist of siloxy units attached to the hydrocarbon chain at the non-chiral end of the molecule; while the second series (Series 2) contain only hydrocarbon chains at the end of the molecule. Series 1 exhibit chiral smectic A (SmA) and smectic C (SmC*). It is observed that slight modifications in either the siloxy or the hydrocarbon chain length has strong effect on the electro-optic properties. Increasing the number of siloxy unit in the chain (Series 1) increases the temperature range of SmA, and reduces the SmA-SmC* transition temperature. All materials have melting temperatures below room temperature, and exhibit high values of induced tilt angles. In Series 2, the materials show a broad SmA temperature range, and melting temperatures much higher than in Series 1. However, the SmA phase is found to supercool to subambient temperatures. If the hydrocarbon chain is shortened, tilt angle, electroclinic coefficient and switching time are significally suppressed. Comparison of the electrooptic performance in SmA between the two series show that Series 1 show a much higher tilt angles than Series 2, while the later exhibit much faster response times.