UV-Induced Stable Planar Alignment of Nematic Liquid Crystals Using a Polypropyleneimine Dendrimer Having a Mesogen Consisting of Cinnamate and Azobenzene Moieties

Haba, Osamu; Itabashi, Hiroki; Sato, Shun; Machida, Ken‐ichi; Koda, T.; Yonetake, Koichiro; Kwak, Musun; Momoi, Yuichi; Kim, Nakwon; Hong, Sangpyo; Kang, Dongwoo; Choi, Youngseok

doi:10.1080/15421406.2015.1026737

Cited by 11 publications

(9 citation statements)

References 8 publications

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“…Haba et al modified the fabrication process by proposing irradiation with polarized UV of an LC-mixture containing a polypropyleneimine dendrimer with peripheral mesogens of cinnamate and azobenzene moieties. 254 They confirmed that the peripheral mesogens induced uniaxial alignment upon polarized UV absorption resulting in homogeneous LC alignment along the uniaxially-aligned peripheral mesogens of the dendrimer. Though the irradiation of polarized UV is useful for inducing homogeneous LC alignment, the required irradiation energy was 360 J/cm 2 ; ie, too large because deteriorating the LC material.…”

Section: Latest Alignment Technologiesmentioning

confidence: 69%

“…The display with a mixture of RM monomer and LC material was then irradiated with unpolarized UV to stabilize homogeneous alignment. Haba et al modified the fabrication process by proposing irradiation with polarized UV of an LC‐mixture containing a polypropyleneimine dendrimer with peripheral mesogens of cinnamate and azobenzene moieties . They confirmed that the peripheral mesogens induced uniaxial alignment upon polarized UV absorption resulting in homogeneous LC alignment along the uniaxially‐aligned peripheral mesogens of the dendrimer.…”

Section: Other Alignment Technologymentioning

confidence: 99%

“…251,252,256 Research for a homogeneous self-alignment has also started in the past few years. The reason is that IPS/FFS-LCD operating modes are mostly chosen for mobile, tablet, Light transmission type 244,245 Self-alignment VA 0.1~2 wt% Unpolarized UV irradiation Light transmission type [246][247][248][249][250][251][252] Self-alignment HA 0.1~2 wt% Polarized UV irradiation Light transmission type 253,254 and PC applications. These in-plane type homogeneouslyaligned (HA) modes are characterized by a wide viewing angle and high transmittance.…”

Section: Latest Alignment Technologiesmentioning

confidence: 99%

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Alignment control technology of liquid crystal molecules

Ishihara

Mizusaki

2019

J Soc Info Display

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Liquid crystal displays are now indispensable in everyday life. The display characteristics considerably depend on the configuration of liquid crystal (LC) molecules and interactions between the LC molecules and an alignment film surface. In this paper, we introduce various methods to control parameters that dominate the LC alignment. These parameters include order parameters, the pretilt angle, the director direction, and surface anchoring strength. We also introduce their evaluation methods. In particular, recent alignment film‐free technology is explained in detail. In addition, details of how these parameters are related to the display characteristics, particularly wide viewing angles and fast response characteristics, are described primarily with reference to recent technologies.

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Section: Latest Alignment Technologiesmentioning

confidence: 69%

Section: Other Alignment Technologymentioning

confidence: 99%

Section: Latest Alignment Technologiesmentioning

confidence: 99%

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Alignment control technology of liquid crystal molecules

Ishihara

Mizusaki

2019

J Soc Info Display

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“…Another question is a possible use of azodendrimers for planar alignment, which is necessary for the twisted nematic (TN) and IPS modes. A new dendrimer was successfully developed for this purpose [25]. It is well known as a command surface [2] that surface azobenzene layer commands the orientation change from homeotropic-to-planar by photo-isomerization of the azobenzene.…”

Section: Dendrimers -Fundamentals and Applicationsmentioning

confidence: 99%

Azodendrimers as a Functional Material

Takezoe¹,

Haba²

2018

Dendrimers - Fundamentals and Applications

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Dendrimers can behave as active functional materials, if they are substituted at their tail ends by azo groups. The dendrimers we developed spontaneously attach to interfaces or surfaces, providing us with a variety of functions. After describing the synthesis of dendrimers and azodendrimers, we first review functions for static uses; alignment surface for liquid crystals (LCs). Then, a major part of this review is devoted to the introduction for dynamic uses. Because of photo-induced trans-cis isomerization, the azodendrimers act as a command surface, which enables us to control LC orientation. Azodendrimer layers were formed at glass substrates, LC droplets in polymers, and surfaces of microparticles in LCs. Photo-controlled trans-and cis-forms, respectively, provide homeotropic and planar orientations of LCs. The photo-irradiation induces dewetting of dendrimer layers as well. Photo-induced orientation changes of LCs provide us with various applications and novel phenomena; photo-controlled macroscopic physical properties such as thermal transport, defect structure changes in LC colloids and LC systems with microinclusions, and even dynamics of inclusions in LCs.

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“…In particular, IPS and FFS modes, which are homogeneous alignment modes, have been remarkably growing recently because these modes exhibit intrinsically high transmittance, wide viewing angle, and touch suitability [6]. However, the self-alignment technology for homogeneous alignment modes is not fully established yet though several investigations have been reported [2,[7][8][9]. Therefore, we have started to develop the homogeneous self-alignment technology toward IPS and FFS mode LCDs.…”

Section: Introductionmentioning

confidence: 99%