Thermodynamic, structural and morphological studies on liquid-crystalline blue phases

Stegemeyer, H.; Blümel, Th.; Hiltrop, K.; Onusseit, Hermann; Porsch, F.

doi:10.1080/02678298608086486

Cited by 237 publications

(35 citation statements)

References 54 publications

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“…Blue phases are liquid-crystalline phases that appear in a very small temperature range between a cholesteric phase and an isotropic phase [2][3][4] . The blue phases can occur by a delicate balance between a structure with a local energetic minimum (double twist alignment of the molecules) and defects (disclination line).…”

Section: Introductionmentioning

confidence: 99%

Fast electro-optical effect in polymer-stabilized blue phases

et al. 2004

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Key challenges in achieving higher-quality liquid crystal displays for future generations are developing new liquid crystal materials with faster electro-optical response and simplifying the fabrication process of devices. Blue phases 1-4 , kinds of liquid crystal phases, have two major advantages over commonly used nematic phases. First, the response is much faster 5-8 . Second, the zero-electric field state is optically isotropic unlike nematic phases, that is, no surface treatment (no rubbing) is necessary, leading to a simplification of the fabrication process. One of the problems of blue phases that the available temperature range is very narrow has been overcome by our recent achievement, the polymerstabilized blue phases 9, 10 . Here we show that the polymer-stabilized blue phases surmount another problem that the blue phase is very fragile to an electric field. We also demonstrate the sufficiently large electric field-induced birefringence and the micro-second response of the polymer-stabilized blue phases without any surface treatment.

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Section: Introductionmentioning

confidence: 99%

Fast electro-optical effect in polymer-stabilized blue phases

et al. 2004

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“…blue phase I (BPI), blue phase II (BPII) and blue phase III (BPIII). [18][19][20] Blue phases are normally found in a very narrow (~2°C) temperature range between the isotropic liquid and a chiral nematic (N*) phase of sufficiently short pitch. Double twist cylinders are believed to exist in BPI and BPII.…”

Section: Introductionmentioning

confidence: 99%

Novel U-shaped liquid crystals for electro-optic devices

et al. 2006

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We would like to report here novel molecular design for electro-optic liquid crystal devices, i.e. catechol derivatives for reduction in threshold voltage and binaphthyl derivatives for blue phases with a wide temperature range. A threshold voltage of a nematic mixture consisting of a host liquid crystal and 10wt% of a catechol derivative, 1-{6-(3,4-difluorophenyloxy)hexyloxy}-2-{6-[4-(4-fluorophenyl)phenyloxy]hexyloxy}benzene, was markedly lower than that of the host LC. The U-shaped compound was found to induce larger dielectric anisotropy in the nematic phase of the mixture than the corresponding monomeric compound. Then, we prepared a homologous series of novel chiral dimeric compounds, (R)-2,2'-bis{6-[4-(2-(2-fluoro-4-butyloxyphenyl)pyrimidine-5-yl)phenyloxy]alkyloxy}-1,1'-binaphthyl. The binaphthyl derivatives with an even number of atoms in the spacers showed a chiral nematic phase, however, those with an odd number of atoms showed a blue phase in a relatively wide temperature range between the isotropic and smectic A phases. We discuss structure-property relationships in the U-shaped system.

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“…This competition results in the mesogens selforganizing into double-twisted cylindrical structures that are separated by disclination lines in the molecular orientation [2], producing three distinct blue phase morphologies. In two cases (blues phases I and II or BPI and BPII), the disclination lines form body-centered or simple cubic lattices [3,4], with lattice spacing in the optical range giving rise to strong reflection of visible light. On the other hand BPIII is thought to be amorphous phase and is optically isotropic [5,6].…”

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confidence: 99%

Magnetic-field-induced suppression of the amorphous blue phase

et al. 2014

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We present magneto-optical measurements on two liquid crystals that exhibit a wide temperature-range amorphous blue phase (BPIII). Magnetic fields up to 25 T are found to suppress the onset of BPIII in both materials by almost 1 °C. This effect appears to increase nonlinearly with the field strength. The effect of high fields on established BPIIIs is also reported, in which we find significant hysteresis and very slow dynamics. Possible explanations of these results are discussed.

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Thermodynamic, structural and morphological studies on liquid-crystalline blue phases

Cited by 237 publications

References 54 publications

Fast electro-optical effect in polymer-stabilized blue phases

Fast electro-optical effect in polymer-stabilized blue phases

Novel U-shaped liquid crystals for electro-optic devices

Magnetic-field-induced suppression of the amorphous blue phase

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