Command Surfaces Research Articles

Command surfaces 12 [1]. Factors affecting in-plane photoregulation of liquid crystal alignment by surface azobenzenes on a silica substrate

Abstract In-plane alignment of nematic liquid crystals was regulated by polarized-light-irradiation of a cell assembled with a silica plate, the surface of which was modified by attaching 4-hexyl-4′-hexyloxyazobenzene at its o-position through surface silylation. The photoisomerizability of the chemisorbed azo-chromophore was affected by their surface density and the nature of photoinactive co-modifiers. The efficiency of the photoregulation of liquid crystal alignment was optimized by two-dimensional dilution of the chromophore with ethyltriethoxysilane (ETS) or 3-aminopropyltriethoxysilane (ATS). As a result, favourable procedure was to modify a silica surface with a crude azo-silylating reagent contaminated by ATS. The rate of the photoinduced reorientation of liquid crystals was followed by monitoring the alteration of the alignment direction of a dichroic dye dissolving in a mesophasic layer upon exposure to linearly polarized light. Exposure energy for the in-plane reorientation of a liquid crystal ...

Command surfaces 14 [1]. Photoregulation of in-plane alignment of a liquid crystal by the photoisomerization of stilbenes chemisorbed on a substrate silica surface

Abstract Stilbenes were attached to a quartz surface at their 2-position by silylation through a spacer to determine the capability to regulate an azimuthal alignment of a nematic liquid crystal by irradiation with linearly polarized light. Liquid crystal molecules aligned perpendicular to the direction of polarization plane of the actinic light, just as in the case of surface azobenzenes. The efficiency of the photoregulation was influenced by excitation wavelength and hence related with an E/Z isomeric ratio in a photostationary state. The irradiation with 260 nm polarized light resulting in the E-isomer as a major component in the photostationary state gave better optical quality of a photoaligned texture when compared with 330 nm irradiation, suggesting that the orientation of liquid crystals is induced by the rod-like E-isomer. Discussion was made on the possibility of the role of phenanthrenes, which were formed upon prolonged irradiation, in the liquid crystal photoalignment.

Command surfaces 15 [1]. Photoregulation of liquid crystal alignment by cinnamoyl residues on a silica surface

Abstract The surface of a silica substrate plate was modified with a cinnamate moiety having a triethoxysilyl group at the ortho-position through a spacer. The plate was employed to assemble a cell filled with a nematic liquid crystal and exposed to linearly polarized 259 nm light to obtain homogeneous alignment. The direction of the alignment was perpendicular to an electric vector of the actinic light. On the contrary, the exposure of the cell to polarized light at 330 nm did not result in homogeneous alignment while the actinic light caused the disappearance of the chromophore. This wavelength effect on the azimuthal photoalignment suggests that the surface-assisted liquid crystal orientation is triggered by the reorientation of the E-isomer of the cinnamate group. This is in marked contrast to a proposed mechanism of a photoalignment by a thin film of a poly(vinyl cinnamate) derivative (Schadt et al., 1993, Jpn J. appl. Phys., 31, 2155); homogeneous alignment is induced by the axially selective photod...

Alignment Photoregulation of a Nematic Liquid Crystal by Surface Adsorption of Aminoalkylated Azobenzenes

AbstractAdsorption behavior of azobenzenes having an aminoalkyl residue onto a silica surface is described. Immersion of a silica plate in a benzene solution of an aminoalkylated azobenzene resulted in efficient adsorption to form face‐to‐face aggregates which are converted into monomeric states by partial desorption. Silica plates adsorbing the azobenzene bearing an aminoalkyl residue were employed to achieve the surface‐assisted photoregulation of alignment of a nematic liquid crystal between homeotropic and planar modes. Based on these observations, a convenient method to prepare command surfaces for the orientational photoregulation of liquid crystals was presented by filling a liquid crystal containing an aminoalkylated azobenzene into an empty cell composed of clear silica plates.

Surface-Assisted Photolithography To Form Anisotropic Dye Layers as a New Horizon of Command Surfaces

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSurface-Assisted Photolithography To Form Anisotropic Dye Layers as a New Horizon of Command SurfacesKunihiro Ichimura, Masayuki Momose, Kazuaki Kudo, Haruhisa Akiyama, and Norio IshizukiCite this: Langmuir 1995, 11, 7, 2341–2343Publication Date (Print):July 1, 1995Publication History Published online1 May 2002Published inissue 1 July 1995https://doi.org/10.1021/la00007a003RIGHTS & PERMISSIONSArticle Views196Altmetric-Citations59LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Photochromic command surface induced switching of liquid crystal optical waveguide structures

We report on optical waveguide structures containing a thin liquid crystal (LC) film held between two photochromic command surfaces. The command surfaces consist of three monomolecular layers of a polymer with azobenzene side chains deposited according to the Langmuir–Blodgett–Kuhn technique. When exposed to light of appropriate wavelength, the command surfaces undergo a trans↔cis photoisomerization process that induces a reversible change in the liquid crystalline orientation. Such an orientation change of the LC alters the optical properties of the optical waveguide. We present experiments on the dynamics of the LC orientation process. The transition is shown to be continuous, with the degree of orientation dependent on the ratio of the cis-trans chromophore concentration ratio in the command surface.

Command surfaces, 10. Novel polymethacrylates with laterally attached azobenzene groups displaying photoinduced optical anisotropy

AbstractPolymethacrylates with laterally attached azobenzenes were prepared to cause molecular reorientation of this chromophore in their thin films by linearly polarized irradiation with an exposure energy of less than ca. 100 mJ/cm2. A homogeneous alignment was induced by assembling a nematic liquid crystal cell using a substrate plate covered with the photoirradiated films. The alignment direction of the cell was controlled by changing the electric vector of the actinic light.

Command surfaces 13(1): photoregulation of in-plane alignment of nematic liquid crystals by cinnamate pendant polymer films.

Command surfaces 13(1): photoregulation of in-plane alignment of nematic liquid crystals by cinnamate pendant polymer films.

Command surface controlled liquid crystalline waveguide structures as optical information storage

We report on optical waveguide structures in which light propagates within a liquid crystal (LC) thin film. In this configuration, the orientation, and therefore the optical properties of the LC waveguide structure are controlled by two photochromic command surfaces, consisting of an ultra thin film of a polymer with azobenzene side chains [K. Ichimura, Y. Suzuki, T. Seki, A. Hosoki, and K. Aoki, Langmuir 4, 1214 (1988)]. When exposed to light of appropriate wavelength, the azobenzene side chains undergo a trans↔cis photoisomerization process inducing a commensurate change in the LC alignment and therefore, in the set of refractive indices of the LC film. Using this effect we could reversibly write information into the LC cell. The size of our test structure was in the range of 50 μm. The stored information was read out by optical waveguide microscopy [W. Hickel and W. Knoll, Appl. Phys. Lett. 57, 1286 (1990)]; the storing times were in the range of several hours.

FT-IR Study of Molecular Orientation and Anisotropy in "Command Surfaces" Formed by Langmuir-Blodgett Films of Azobenzene Amphiphilic Polymers

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFT-IR Study of Molecular Orientation and Anisotropy in "Command Surfaces" Formed by Langmuir-Blodgett Films of Azobenzene Amphiphilic PolymersNorihisa Katayama, Yukihiro Ozaki, Takahiro Seki, Takashi Tamaki, and Keiji IriyamaCite this: Langmuir 1994, 10, 6, 1898–1902Publication Date (Print):June 1, 1994Publication History Published online1 May 2002Published inissue 1 June 1994https://doi.org/10.1021/la00018a047RIGHTS & PERMISSIONSArticle Views330Altmetric-Citations48LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts Get e-Alerts

Command surfaces, 6 Azimuthal orientation of liquid crystals photo‐controlled by an azobenzene pendent polymer

Photoirradiation of a thin film of a homopolymer of 4-methacryloyloxyazobenzene with linearly polarized visible light, followed by cell fabrication, was found to generate a homogeneous alignment of nematic liquid crystals. In contrast, no alignment regulation was attained when the cell fabrication is made before photoirradiation, suggesting that the photo-induced persistent reorientation of the azo-chromophore is disturbed by penetration of the liquid crytal molecules into the polymer film to enhance the randomization of the oriented azobenzene chromophores

"Command surfaces" of Langmuir-Blodgett films. Photoregulations of liquid crystal alignment by molecularly tailored surface azobenzene layers

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT"Command surfaces" of Langmuir-Blodgett films. Photoregulations of liquid crystal alignment by molecularly tailored surface azobenzene layersTakahiro Seki, Masako Sakuragi, Yuji Kawanishi, Takashi Tamaki, Ryoichi Fukuda, Kunihiro Ichimura, and Yasuzo SuzukiCite this: Langmuir 1993, 9, 1, 211–218Publication Date (Print):January 1, 1993Publication History Published online1 May 2002Published inissue 1 January 1993https://doi.org/10.1021/la00025a041RIGHTS & PERMISSIONSArticle Views1203Altmetric-Citations243LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts Get e-Alerts

Reversible alignment change of liquid crystals induced by photochromic molecular films, 15. Convenient methods to prepare “command surfaces” by surface‐selective modification of thin films of poly(vinyl alcohol) with azobenzene units

AbstractA thin film of poly(vinyl alcohol) (PVA of different saponification degree) coated on a glass plate was subjected to a surface‐selective introduction of azobenzene moieties by treatment with a solution of 4‐(4‐hexylphenylazo) phenoxyacetyl chloride/pyridine or 4‐(4‐hexylphenylazo) phenoxybutanal /ptoluenesulfonic acid. Cells were fabricated by sandwiching a nematic liquid‐crystalline material between two surface‐modified glass plates. Alternating exposure to UV and visible light causes a reversible alignment of the liquid crystal molecules. Rubbing of the surface‐modified PVA resulted in an improved optical quality of the cell and enabled us to construct a photoresponsive twisted nematic cell. The advantages of the present method for preparing “command surfaces” are discussed from a practical point of view.

Photochemical alignment regulation of a nematic liquid crystal by Langmuir-Blodgett layers of azobenzene polymers as "command surfaces"

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotochemical alignment regulation of a nematic liquid crystal by Langmuir-Blodgett layers of azobenzene polymers as "command surfaces"Takahiro Seki, Takashi Tamaki, Yasuzo Suzuki, Yuji Kawanishi, Kunihiro Ichimura, and Koso AokiCite this: Macromolecules 1989, 22, 8, 3505–3506Publication Date (Print):August 1, 1989Publication History Published online1 May 2002Published inissue 1 August 1989https://doi.org/10.1021/ma00198a056RIGHTS & PERMISSIONSArticle Views295Altmetric-Citations68LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (302 KB) Get e-Alerts Get e-Alerts