Liquid crystals stabilized by polymer networks

Sonin, A. S.; Churochkina, N. A.

doi:10.1134/s0965545x10050019

Cited by 20 publications

(18 citation statements)

References 62 publications

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“…A PSCLC consists of the in situ formation of an anisotropic polymer within a LC matrix from the polymerization and crosslinking with UV light of a small amount of photoreactive mesogens (<10 wt. typically) 135–137. The LC organization is consequently transferred onto the network morphology.…”

Section: Broadening the Wavelength Bandgapmentioning

confidence: 99%

Cholesteric Liquid Crystals with a Broad Light Reflection Band

2012

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The cholesteric-liquid-crystalline structure, which concerns the organization of chromatin, collagen, chitin, or cellulose, is omnipresent in living matter. In technology, it is found in temperature and pressure sensors, supertwisted nematic liquid crystal displays, optical filters, reflective devices, or cosmetics. A cholesteric liquid crystal reflects light because of its helical structure. The reflection is selective - the bandwidth is limited to a few tens of nanometers and the reflectance is equal to at most 50% for unpolarized incident light, which is a consequence of the polarization-selectivity rule. These limits must be exceeded for innovative applications like polarizer-free reflective displays, broadband polarizers, optical data storage media, polarization-independent devices, stealth technologies, or smart switchable reflective windows to control solar light and heat. Novel cholesteric-liquid-crystalline architectures with the related fabrication procedures must therefore be developed. This article reviews solutions found in living matter and laboratories to broaden the bandwidth around a central reflection wavelength, do without the polarization-selectivity rule and go beyond the reflectance limit.

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Section: Broadening the Wavelength Bandgapmentioning

confidence: 99%

Cholesteric Liquid Crystals with a Broad Light Reflection Band

2012

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“…Therefore, we focused on the alignment‐controlled (AC) PDLC cell in which the LC and the polymer aligned in the same direction as a LGP of our backlight system. The AC‐PDLC cell is fabricated by using mixture of the LC monomers and the LC materials and photo‐polymerizing the mixtures in the condition where they aligned self‐assembly in the same direction.…”

Section: Principle Of the Local Dimming Light‐guiding Plate‐type Backmentioning

confidence: 99%

“…Recently, vertically‐aligned and parallel‐aligned modes have been proposed as a LC mode for the AC‐PDLC. However, vertically‐aligned mode has a problem of high‐driving voltage because of the low dielectric anisotropy of negative LC materials . From earlier, we adopted a parallel‐aligned PDLC shown in Fig.…”

Section: Principle Of the Local Dimming Light‐guiding Plate‐type Backmentioning

confidence: 99%

Local dimming light-guiding plate type backlight system using alignment-controlled polymer-dispersed liquid crystals

Eri

Ishinabe

Fujikake

2017

Jnl Soc Info Display

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A new technology which enables a local brightness control according to the displayed images has been expected in the thin and lightweight backlight systems to improve a contrast ratio and power consumption of the liquid crystal displays (LCDs). In this paper, we have proposed a novel local‐dimming backlight system using alignment‐controlled polymer‐dispersed liquid crystals as a light‐guiding plate and investigated the forming conditions of polymer‐dispersed liquid crystals to achieve both a high‐luminance ratio and a fast response speed. As a result, we found that a luminance ratio and response speed of the backlight system can be improved by using bifunctional LC monomer materials and forming fine and rigid polymer network in the LCs, and achieved high luminance ratio of 16:1 and fast response time less than 0.5 ms. In addition, we fabricated the twisted nematic‐mode LCD using the local dimming light‐guiding plate‐type backlight based on this design, and successfully realized eight times higher contrast ratio than that of the traditional twisted nematic‐mode LCD.

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“…Liquid crystal (LC) gels, also called polymer-stabilized LCs, are fabricated via UV light polymerization of bifunctional reactive mesogens dissolved with a photoinitiator in a conventional low molar mass LC [1][2][3]. During the photoreaction, the structure of the LC is copied by the polymer network [4], resulting in a similar morphology which in turn influences the LC structure.…”

Section: Introduction a Motivation Of The Researchmentioning

confidence: 99%

Cholesteric liquid crystal gels with a graded mechanical stress

2014

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In cholesteric liquid-crystalline gels, the mechanical role of the polymer network over the structure of the whole gel has been ignored. We show that it is the stress gradient exerted by the network over the helical structure that drives the broadening of the optical band gap, as evidenced by the absence of a gradient in chiral species. Model calculations and finite-difference time-domain simulations show that the network acts as a spring with a stiffness gradient. The present results indicate a revision to the common understanding of the physical properties of liquid-crystalline gels is necessary when a concentration gradient in a polymer network is present.

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Liquid crystals stabilized by polymer networks

Cited by 20 publications

References 62 publications

Cholesteric Liquid Crystals with a Broad Light Reflection Band

Cholesteric Liquid Crystals with a Broad Light Reflection Band

Local dimming light-guiding plate type backlight system using alignment-controlled polymer-dispersed liquid crystals

Cholesteric liquid crystal gels with a graded mechanical stress

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