Photocontrolled Orientation of Discotic Liquid Crystals

Ichimura, Kenji; Furumi, Seiichi; Morino, Shin’ya; Kidowaki, Masatoshi; Nakagawa, Masamichi; Ogawa, Masaaki; Nishiura, Yousuke

doi:10.1002/1521-4095(200006)12:13<950::aid-adma950>3.3.co;2-m

Cited by 12 publications

(12 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, highly viscous or solidified LC materials, such as polymer LCs, are often exposed to air. Until now, the role of the free surface regarding the LC orientation has hardly been taken into account, except for the discotic LC film systems that form a hybrid orientation between an alignment film on a solid surface and the air262728. In these cases, modifications on the solid substrate side are still required.…”

Section: Discussionmentioning

confidence: 99%

Free-surface molecular command systems for photoalignment of liquid crystalline materials

et al. 2014

View full text Add to dashboard Cite

The orientation of liquid crystal molecules is very sensitive towards contacting surfaces, and this phenomenon is critical during the fabrication of liquid crystal display panels, as well as optical and memory devices. To date, research has focused on designing and modifying solid surfaces. Here we report an approach to control the orientation of liquid crystals from the free (air) surface side: a skin layer at the free surface was prepared using a non-photoresponsive liquid crystalline polymer film by surface segregation or inkjet printing an azobenzene-containing liquid crystalline block copolymer. Both planar-planar and homoeotropic-planar mode patterns were readily generated. This strategy is applicable to various substrate systems, including inorganic substrates and flexible polymer films. These versatile processes require no modification of the substrate surface and are therefore expected to provide new opportunities for the fabrication of optical and mechanical devices based on liquid crystal alignment.

show abstract

Section: Discussionmentioning

confidence: 99%

Free-surface molecular command systems for photoalignment of liquid crystalline materials

et al. 2014

View full text Add to dashboard Cite

show abstract

“…1,4,5,72 Such photocontrol becomes particular effective in relatively viscous molecular organized media such as polymeric LCs [77][78][79] and LB films. 80,81 Optically induced surface anisotropy in the Az polymer films has been successfully transferred to the orientation of various types of LC materials, as widely investigated by Ichimura et al, including thermotropic chiral nematic 82 and discotic LCs, 83 lyotropic LCs, 84 and also side chain liquid crystalline polymers. 85 Exposure of the 6Az10-PVA monolayer to LPL induces the in-plane orientation of Az side chain as stated above.…”

Section: Conformational and Orientational Control Of Polysilane Filmsmentioning

confidence: 99%

Dynamic Photoresponsive Functions in Organized Layer Systems Comprised of Azobenzene-containing Polymers

Seki

2004

Polym J

View full text Add to dashboard Cite

ABSTRACT:Azobenzene (Az)-containing polymers provide fascinating photoresponsive actuation systems. When they are organized at interfaces, the motion of Az unit occurring at a molecular (sub-nano) scale can be transferred and amplified to larger scales of materials. This review article focuses to selected research topics on organized layer systems of Az-containing polymers proceeding in our laboratory. They involve i) photomechanical response of monolayers at nanometer levels in thickness and centimeters in area, ii) monolayer-mediated photoorientation of polymer (polysilane) and mesoporous silica at nano-to sub-micrometer levels in thickness, and iii) instant mass migration triggered by patterned photoirradiation occurring at distances over micrometer levels. In every system, strong cooperative interplays between the Az unit and organized molecular or macromolecular assemblies play the essential roles. Promotions of these research areas are anticipated to provide wide and new opportunities for material processing and creation of new classes of photofuncitional soft materials.

show abstract

“…Approaches based on the Langmuir-Blodgett technique have provided a precise understanding of the effects of the molecular design and packing density on the command layer. 52,53 Successive explorations have revealed that the command layer can control orientations for a variety of materials, including discotic LCs, 54,55 lyotropic chromonic LCs, [56][57][58] LC polymers, 59,60 semiconducting molecules 61,62 and mesostructured organic-inorganic hybrids. [63][64][65][66][67][68] Photoalignment methods have recently become of practical importance in industry.…”

Section: Introductionmentioning

confidence: 77%

New strategies and implications for the photoalignment of liquid crystalline polymers

Seki

2014

Polym J

141

118

View full text Add to dashboard Cite

The photoalignment of liquid crystalline materials has been studied extensively over the past two and a half decades and has recently become of technological importance in the liquid crystal display panel industry. This review introduces recent attempts at the photoalignment of liquid crystalline polymers and focuses on two aspects. First, strategies to ensure effective in-plane alignment of photoresponsive mesogens are highlighted. Despite the numerous investigations reported to date, film systems have not been well optimized in terms of realizing efficient photoreactions that consider the mesogen orientations. Second, new photoalignable systems composed of block copolymers with surface-grafted polymers and block copolymer films are introduced. The photoalignment processes in these mesoscopic systems involve strong cooperative motion of the different hierarchical size features. In the course of these approaches, a new strategic platform, photoalignment of liquid crystalline polymers via commanding from the free surface, is proposed. These approaches are expected to offer new concepts and possibilities for smart light-responsive materials and systems. Polymer Journal (2014) 46, 751-768; doi:10.1038/pj.2014.68; published online 13 August 2014 INTRODUCTIONPhotoreactions in ordered media have been the subject of numerous studies. In liquid crystal (LC) systems, molecules are packed with substantial motional freedom, and photoreactions trigger changes in the packing state or the collective molecular orientation. The effects can be amplified to the mesoscopic, microscopic and even macroscopic levels due to strong motional cooperativity. Photochromic reactions have frequently been incorporated in LC media because of their repeatability for controlling material properties. This approach has provided various types of smart, light-responsive materials 1 exhibiting surface-mediated photoalignment of LC materials, 2-6 photoinduced phase transitions, 7-12 photoorientation/addressing of polymer thin films, 13-18 photoinduced mass migrations, [19][20][21][22][23][24][25][26][27][28] phototactic sliding motions, 29-31 photo-driven motions and morphology of monolayers, 32-35 and macroscopic photomechanical deformations. [36][37][38][39][40][41][42][43][44][45][46] Photoalignment research and technology started in 1988 with the discovery of the reversible alignment control of nematic LCs by the photoisomerization of azobenzene on a substrate surface (Figure 1) by Ichimura et al. 47 It was demonstrated that the E/Z (trans/cis) photoisomerization of an azobenzene monolayer on a substrate can switch the alignment of nematic LC molecules between the homeotropic and planar modes. This active functional surface was dubbed a 'command surface' or 'command layer.' Shortly after this finding, Gibbons et al., 48 Dyadyusha et al. 49 and Schadt et al. 50 showed that angular selective excitation of an azo dye-doped polyimide or a photocrosslinkable polymer film with linearly

show abstract

Photocontrolled Orientation of Discotic Liquid Crystals

Cited by 12 publications

References 0 publications

Free-surface molecular command systems for photoalignment of liquid crystalline materials

Free-surface molecular command systems for photoalignment of liquid crystalline materials

Dynamic Photoresponsive Functions in Organized Layer Systems Comprised of Azobenzene-containing Polymers

New strategies and implications for the photoalignment of liquid crystalline polymers

Contact Info

Product

Resources

About