Banana-Shaped Compounds—A New Field of Liquid Crystals

Pelzl, G.; Diele, Siegmar; Weißflog, W.

doi:10.1002/(sici)1521-4095(199906)11:9<707::aid-adma707>3.0.co;2-d

Cited by 905 publications

(671 citation statements)

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“…Following the pioneering work of Niori et al, [14] achiral BM have already been shown to yield a variety of Sm phases with ferro-, ferri-or antiferroelectric properties. [15][16][17] To display ferroelectric response in the nematic phase, molecules should organize so that their individual dipoles pile up coherently to produce a large overall polarization P s , rather than canceling it out. BM seem promising in this respect, as their bow shape coupled with a transverse dipole could lead to a local packing favoring head-to-tail dipole arrangement and their consequent summing up.…”

Section: Introductionmentioning

confidence: 99%

Ferroelectric Response and Induced Biaxiality in the Nematic Phase of Bent‐Core Mesogens

Francescangeli

Stanić

Torgova

et al. 2009

Adv Funct Materials

188

170

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The still undiscovered fluid ferroelectric nematic phase is expected to exhibit a much faster and easier response to an external electric field compared to conventional ferroelectric smectic liquid crystals; therefore, the discovery of such a phase could open new avenues in electro‐optic device technology. Here, experimental evidence of a ferroelectric response to a switching electric field in a low molar mass nematic liquid crystal is reported and connected with field‐induced biaxiality. The fluid is made of bent‐core polar molecules and is nematic over a range of 120 °C. Combining repolarization current measurements, electro‐optical characterizations, X‐ray diffraction and computer simulations, ferroelectric switching is demonstrated and it is concluded that the response is due to field‐induced reorganization of polar cybotactic groups within the nematic phase. This work represents significant progress toward the realization of ferroelectric fluids that can be aligned at command with a simple electric field.

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Section: Introductionmentioning

confidence: 99%

Ferroelectric Response and Induced Biaxiality in the Nematic Phase of Bent‐Core Mesogens

Francescangeli

Stanić

Torgova

et al. 2009

Adv Funct Materials

188

170

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“…The fluid smectic A (SmA) and smectic C (SmC) phases have diffused lamellar structures described by a density wave with a period d corresponding to the smectic layer spacing. 2 In the uniaxial SmA phase, the axes of the orientational and translational orders coincide with each other in which the director n is parallel to the smectic layer normal z. In the biaxial SmC phase, n is tilted relative to z by the tilt angle h that varies with temperature.…”

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confidence: 99%

Anomalous temperature dependence of layer spacing of de Vries liquid crystals: Compensation model

Merkel

Kocot

Vij

et al. 2016

Applied Physics Letters

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Smectic liquid crystals that exhibit temperature independent layer thickness offer technological advantages for their use in displays and photonic devices. The dependence of the layer spacing in SmA and SmC phases of de Vries liquid crystals is found to exhibit distinct features. On entering the SmC phase, the layer thickness initially decreases below SmA to SmC (TA–C) transition temperature but increases anomalously with reducing temperature despite the molecular tilt increasing. This anomalous observation is being explained quantitatively. Results of IR spectroscopy show that layer shrinkage is caused by tilt of the mesogen's rigid core, whereas the expansion is caused by the chains getting more ordered with reducing temperature. This mutual compensation arising from molecular fragments contributing to the layer thickness differs from the previous models. The orientational order parameter of the rigid core of the mesogen provides direct evidence for de Vries cone model in the SmA phase for the two compounds investigated.

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“…[1][2][3][4][5][6][7][8][9] The bent-core molecules strongly nanosegregate, leading to the formation of polar and chiral arrangements of the bent cores into planar or modulated layers. Subtle interactions between layers can be manipulated to produce a variety of ferro-or anti-ferroelectric phases.…”

Section: Doi: 101002/adma201004482mentioning

confidence: 99%

Orientation of a Helical Nanofilament (B4) Liquid‐Crystal Phase: Topographic Control of Confinement, Shear Flow, and Temperature Gradients

Yoon

Shen

et al. 2011

Advanced Materials

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Banana-Shaped Compounds—A New Field of Liquid Crystals

Cited by 905 publications

References 0 publications

Ferroelectric Response and Induced Biaxiality in the Nematic Phase of Bent‐Core Mesogens

Ferroelectric Response and Induced Biaxiality in the Nematic Phase of Bent‐Core Mesogens

Anomalous temperature dependence of layer spacing of de Vries liquid crystals: Compensation model

Orientation of a Helical Nanofilament (B4) Liquid‐Crystal Phase: Topographic Control of Confinement, Shear Flow, and Temperature Gradients

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