Photofabrication of Micro-Patterned Polarizing Elements for Stereoscopic Displays

Matsunaga, Daisaku; Tamaki, Takashi; Akiyama, Haruhisa; Ichimura, Kunihiro

doi:10.1002/1521-4095(20021016)14:20<1477::aid-adma1477>3.0.co;2-l

Cited by 88 publications

(57 citation statements)

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“…8,9 The control of the in-plane LC alignment direction has been achieved via an axis-selective photoreaction in photosensitive materials using LP light. 10 Many materials have been developed as the photoalignment layer to align not only LCs but also other functional materials such as dichroic dyes, 11,12 electroluminescent materials, 1315 mesoporous silica, 16,17 and conducting materials.…”

Section: ç Photoalignment For Liquid Crystalsmentioning

confidence: 99%

Photoalignment and Photoinduced Molecular Reorientation of Photosensitive Materials

Kawatsuki¹

2011

Chemistry Letters

116

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Photosensitive materials for photoalignment of liquid crystals (LCs) and photoinduced molecular reorientation are described, especially focusing on azobenzene-containing materials and photocrosslinkable polymers. All the materials generate photoinduced optical anisotropy by means of linearly polarized (LP) light exposure. The large optical anisotropy is induced when the axis-selective photoreaction is accompanied by molecular reorientation. Ç IntroductionDue to practical applications of the alignment layer of functional materials such as low-molecular-weight liquid crystals (LCs), photoalignment and photoinduced molecular reorientation of photosensitive films have received much attention. 13 Additionally, these films have been investigated for molecularly oriented birefringent devices due to the absence of mechanical damage, absence of electric charge, and patterning ability.13 Photoinduced optical and physical anisotropies can be generated in a photoreactive polymeric film by light exposure because the photoreaction changes the inherent refractive index of the molecules. Irradiating with linearly polarized (LP) light causes the photosensitive molecules parallel to the polarization (E) of LP light (y axis) to preferentially photoreact (Figure 1). This axis-selective photoreaction leads to optical anisotropy (birefringence) between the y axis and xz plane if the photoreaction changes the inherent refractive indices of the molecules.To obtain uniaxial alignment of LCs on thin polymeric films, the LC photoalignment layer should exhibit optical or physical anisotropy. Under this circumstance, a large molecular orientation of the film is unnecessary. The anisotropic interaction between the photoalignment layer and LC molecules induces uniaxially oriented LC molecules.1 Because the axis-selective photoreaction induces a small change in the refractive index of the photoalignment layer, 4 a thick film is necessary for optically anisotropic devices such as a birefringent film. Consequently, a large optical anisotropy in the photoreacted film is generated when molecular reorientation occurs during an anisotropic photoreaction. 3Various types of materials that undergo an axis-selective photoreaction to generate photoinduced optical anisotropy have been investigated, including azobenzene-containing polymers 2,57 and photocrosslinkable polymers. 1,3,4 For the azobenzene molecules, axis-selective photoisomerization is generated when the film is irradiated with linearly polarized (LP) light (Figure 2a). Similarly, irradiating with LP ultraviolet (LPUV) light induces both axis-selective [2 + 2] photo/cycloaddition (photocrosslinking) reaction and photoisomerization for cinnamic ester derivatives (Figure 2b). Low-molecular LC molecules easily align on these anisotropically photoreacted films. When an axis-selective photoreaction occurs without generating molecular reorientation, the photoinduced birefringence (¦n) is less than 0.01. 4 An anisotropic photoreaction combined with molecular motion may generate a large optica...

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Section: ç Photoalignment For Liquid Crystalsmentioning

confidence: 99%

Photoalignment and Photoinduced Molecular Reorientation of Photosensitive Materials

Kawatsuki¹

2011

Chemistry Letters

116

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“…Macroscopic alignment of LCs is caused as a result of anisotropic interface interactions between the LC and the surface of polymer films. It allows photopatterning of the LC alignment, so irradiation with polarized light can regulate alignment direction and tilt angle of nematic LCs [7]. In addition to the conventional rubbing technique there are many studies about the photoinduced alignment of LCs using different photochromic polymers [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…It allows photopatterning of the LC alignment, so irradiation with polarized light can regulate alignment direction and tilt angle of nematic LCs [7]. In addition to the conventional rubbing technique there are many studies about the photoinduced alignment of LCs using different photochromic polymers [7][8][9]. Rubbing of polyimide films is the conventional method to produce LC displays, but it has a number of disadvantages especially due to dust and electrostatic effects.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced optical anisotropy in new poly(amide imide)s with azobenzene units

Schab‐Balcerzak

Sapich²,

Stumpe

2005

Polymer

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“…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: 99%

New strategies and implications for the photoalignment of liquid crystalline polymers

Seki

2014

Polym J

137

118

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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

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Photofabrication of Micro-Patterned Polarizing Elements for Stereoscopic Displays

Cited by 88 publications

References 0 publications

Photoalignment and Photoinduced Molecular Reorientation of Photosensitive Materials

Photoalignment and Photoinduced Molecular Reorientation of Photosensitive Materials

Photoinduced optical anisotropy in new poly(amide imide)s with azobenzene units

New strategies and implications for the photoalignment of liquid crystalline polymers

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