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LC Cell (lc + cell)

Distribution by Scientific Domains

Polymers and Materials Science	85%

Selected Abstracts

Photogeneration of High Pretilt Angles of Nematic Liquid Crystals by Non-Polarized Light Irradiation of Azobenzene-Containing Polymer Films,

ADVANCED FUNCTIONAL MATERIALS, Issue 3 2004
S. Furumi
Abstract A vertical-alignment (VA) cell of nematic liquid crystals (LCs) was prepared using photoirradiated thin films of a poly(methacrylate) with mesogenic moieties of 4-trifluoromethoxyazobenzene as the side chains. Optical anisotropy was generated by oblique irradiation of the azobenzene-containing polymer films with non-polarized UV light, followed by annealing treatment to enhance the photodichroism, which displayed thermal stability. The combination of oblique exposure to non-polarized UV light and subsequent annealing treatment brought about high pretilt angles of nematic LCs so that a photoaligned VA LC cell was fabricated. The photopatterned LC cell exhibited electro-optical properties with excellent optical quality when a voltage was applied even after heating at 100,°C for several hours. [source]

UV-Curable Azobenzene Polymer Bearing Photo-Crosslinkable Moiety for Stabilization of Photo-Fabricated Surface Relief Structure

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2002
Tatsumi Kimura
Abstract In order to find a new class of photo-processable liquid crystalline (LC) aligning material, five kinds of new maleimide-based copolymers bearing both azobenzene and cinnamate moieties with different functionalization ratio have been synthesized. The properties of these five copolymers were compared regarding physical and chemical properties that are required for our aim. The photo-induced surface relief (PSR) gratings could be fabricated on the films of these copolymers using an Ar+ laser (,,=,488 nm), and were successfully immobilized and bleached by UV-light irradiation that causes photo-crosslinking of the cinnamate moiety and photo-degradation of the azobenzene moiety, respectively. The PSR inscription rate and the thermal stability have been investigated regarding the functionalization ratio between cinnamate and azobenzene side chain. The residual ratio of the PSR structure after UV-curing was increased with increasing photo-crosslinkable moiety. It was confirmed that the UV-cured PSR grating structure becomes transparent at visible wavelength and was able to align LC molecules parallel to the grating direction. Polarized optical microscope image of LC cell aligned by the PMPDC 21-18 film with UV-cured PSR structure (0°). [source]

Liquid crystal alignment property of n -alkylthiomethyl- or n -alkylsulfonylmethyl-substituted polystyrenes

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 12 2009
Hyo Kang
Abstract We synthesized a series of n -alkylthiomethyl-substituted polystyrenes (#T-PS, #,=,4, 8, 12, and 16) and n -alkylsulfonylmethyl-substituted polystyrenes (#S-PS, #,=,4, 8, 12, and 16), where # is the number of carbon atoms in the n -alkyl side group of the polymers, using polymer analogous reactions to investigate their liquid crystal (LC) alignment properties. In general, the LC cell fabricated using the polymer film having a longer n -alkyl side group, a thioether linkage group, and a higher molar content of n -alkyl side group showed homeotropic LC alignment behavior with a pretilt angle of about 90°. The homeotropic alignment behavior was well correlated with the surface energy of the polymer films; when the positive dielectric anisotropic LC (ZLI-5900-000 from Merck) and negative dielectric anisotropic LC (MLC-7026-000 from Merck) were used to fabricate the LC cells, homeotropic alignment was observed when the surface energy values of the polymer were smaller than about 25 and 32,mJ/m2, respectively. Copyright © 2009 John Wiley & Sons, Ltd. [source]

The haemopoietic growth factor, Flt3L, alters the immune response induced by transcutaneous immunization

IMMUNOLOGY, Issue 1 2002
Maria E. Baca-Estrada
Summary Topical application of antigen induces antigen-specific humoral and cellular immune responses. In this study we examined whether expansion of dendritic cells (DC) by Flt3 ligand (Flt3L) treatment influences the induction of immune responses following transcutaneous immunization. Mice were treated intraperitoneally with Flt3L or phosphate-buffered saline (PBS) and immunized transcutaneously with hen egg lysozyme (HEL). Flt3L-treated mice developed lower HEL-specific cellular and humoral immune responses than PBS-treated mice. However, in the presence of cholera toxin (CT), a potent adjuvant for mucosal and transcutaneous immunization, Flt3L-treated mice developed significantly higher cellular and humoral immune responses to HEL when compared to PBS-treated mice. We assessed whether the immunomodulatory effects of CT were a result of activation of epidermal dendritic cells (Langerhans' cells; LC). Our results indicate that within 8,12 hr of topical application of CT, epidermal LC cells lose their dendritic morphology and become rounder in appearance. In addition, we observed enhanced expression of major histocompatibility complex (MHC) class II, and of adhesion molecules CD11c and intracellular adhesion molecule-1 (ICAM-1). Our observations support the concept that the state of activation of DC in the skin is central to the regulation of immune responses. This information is relevant to the design of effective transcutaneous vaccination strategies. [source]

4-Alkylphenoxymethyl-Substituted Polystyrenes for Liquid Crystal Alignment Layers

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 11 2009
Hyo Kang
Abstract We synthesized a phenoxymethyl-substituted polystyrene (PHP) and a series of 4-alkylphenoxymethyl-substituted polystyrenes, where the alkyl group is (CH2)nH (n,=,1, 2, 4, 6, and 8), using polymer analogous reactions, in order to study the effect of the phenoxymethyl and 4-alkylphenoxymethyl side groups on the liquid crystal (LC) alignment properties. The LC cell fabricated with the rubbed PHP film exhibited homogeneous planar and perpendicular LC alignment with respect to the rubbing direction. On the contrary, the LC cells made from the 4-alkylphenoxymethyl-substituted polystyrenes showed homeotropic LC alignment behaviors even at a very high rubbing density of 250, regardless of the length of the alkyl groups. Previously, n -alkylsulfonylmethyl-substituted polystyrenes with alkyl groups having more than 8 carbons (n,>,8) showed homeotropic LC alignment behavior. Therefore, the additional phenoxy group in the side chain was found to improve the homeotropic LC aligning ability of the polystyrene derivatives. [source]