New Ferroelectric Liquid Crystalline Materials with Properties Suitable for Surface Stabilized and Deformed Helix Effects

Abstract

Liquid crystals (LC) are widely used in optical devices. New electro-optic effects are still being established. The requirements of such devices increases thus still new materials are elaborated for such purpose. In this review, two electro-optic effects are described, namely Surface Stabilized Ferroelectric LC (SSFLC) and Deformed Helix Ferroelectric LC (DHFLC) effects. New ferroelectric liquid crystal mixtures were formulated which can be used in devices operating on the basis of the mentioned electro-optic effects. Two ways of mixture preparation have been used: mixing of chiral components or mixing of achiral components with addition of a small amount of chiral dopant. The ferroelectric mixtures with very short (less than 200 nm) or very long (more than 1 μm) pitches are discussed. The mixtures meet almost all requirements of SSFLC and DHFLC effects and therefore, have important prospects for applications in optical sensors.

The Influence of the Molecular Structure of Compounds on Their Properties and the Occurrence of Chiral Smectic Phases

“…The ferroelectric phase (SmC*) was predicted and then discovered by Meyer et al in 1975 [13], and antiferroelectricity in liquid crystals was discovered by Chandani et al in 1989 [14]. Practical applications have only liquid-crystalline mixtures [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] because the composition's tuning allows us to make the optimized ferro-or antiferroelectric mixtures. It is not easy to synthesize compounds with the desired properties.…”

Synthesis, Mesomorphic Properties and Application of (R,S)-1-Methylpentyl 4′-Hydroxybiphenyl-4-carboxylate Derivatives

“…[3][4][5]. Liquid crystalline mixtures are widely used in optical devices; therefore, new materials are constantly being developed for this purpose [6][7][8][9][10][11]. The use of the racemates also leads to a reduction in the preparation costs of the liquid crystalline The racemates can be used as dopants for the liquid crystalline mixtures, improving some of their properties, such as the antiferroelectric phase range, the helical pitch length, the reduction of the rotational viscosity, the decrease of the values of the spontaneous polarization, etc.…”

“…[3][4][5]. Liquid crystalline mixtures are widely used in optical devices; therefore, new materials are constantly being developed for this purpose [6][7][8][9][10][11]. The use of the racemates also leads to a reduction in the preparation costs of the liquid crystalline mixtures.…”