This study reports the electric switching behaviors and dielectric properties of the ferroelectric smectic-A (SmAPF), anti-ferroelectric smectic-A (SmAPA), anti-ferroelectric SmCAPA, and smectic-A (SmA) phases formed by mixing the bent-shaped dimeric molecules, α,ω-bis­(4-alkoxyanilinebenzylidene-4′-carbonyloxy)­pentanes. These four phases each show characteristic features. The SmAPF shows a low threshold electric field for ferroelectric switching and a large dielectric strength due to the collective fluctuation mode of dipoles at around 500 Hz. Both the threshold electric field and dielectric strength are strongly dependent on the cell thickness. The threshold field decreases to 0.1 V μm–1, and the dielectric strength increases up to a huge value of 10,000 as the cell thickness increases up to 80 μm. The SmAPA also shows a similar collective mode at around 2 kHz with a relatively small dielectric strength (around 200), which may be induced by the anti-phase rotation of dipoles in adjacent layers. In these collective modes, the dielectric strength is found to be inversely proportional to the switching threshold field. On the other hand, another anti-ferroelectric SmCAPA as well as the paraelectric SmA show only the non-collective mode (i.e., rotational relaxation of individual molecules around their short axes) at a high frequency of around 100 kHz.

We present the dielectric relaxation properties of the ferroelectric smectic-A (SmAPF) phase formed by the mixture of bent-shaped dimeric molecules, α,ω-bis(4-alkoxyanilinebenzylidene-4′-carbonyloxy)pentanes with different alkyl chain lengths. The SmAPF phase shows...

Three kinds of bent-shaped dimeric molecules are synthesized by fluorine substitution of C16 molecules, and influences of the substitution on the polar smectic phases are examined. The fluorine-substituted C16 molecules form the SmAP F and SmC A P A phases. The transition temperatures decrease by 20−30 °C without significantly changing the temperature span of the smectic phase, and the switching rates to the ferroelectric state become 5−10 μs, which are fairly shorter than 250 μs of C16. These behaviors are considered to be caused by the decrease in the intermolecular force and the decrease in the viscosity. The anchoring behavior also appears to be different. On the indium tin oxide (ITO)-coated cell, the fluorine-substituted molecules are homogeneously aligned with the bent (polar) axes perpendicular to the surface, while the bent axes of ordinary bent-shaped molecules lie parallel to the surface. This may be attributable to the repulsion between the fluorine and ITO electrodes. Further, the fluorine substitution can increase the dipole moment of the molecule. The largest dipole moment obtained is 7.94 D, and this leads to a huge reversal polarization of 2.42 μC cm −2 , which is much higher compared to those reported in the bent-shaped molecules.

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The sub-micrometer and micrometer-scale self-assembled structures of a series of amphiphilic dendrons constructed from the building blocks of aromatic amide, triethylene glycol, and octadecyl groups were evaluated. The dendrons from the first to the third generations were prepared by a straightforward synthesis. Self-assembling study of the dendrons was carried out by the characterization of the films prepared by casting from the solutions using scanning electron microscopy and atomic force microscopy. The solution of the first generation amphiphilic dendron provided the dot-like or fibrous structures with a diameter of several hundred nanometers. The hexagonally arranged open pores of approximately 1.1- 1.4 μm were formed by casting the solution of the second and the third generation amphiphilic dendrons under a moist air flow.