Preparation of electro-optical active liquid crystal microdomains by the sol-gel process

Abstract Thin films containing liquid crystal droplets have been prepared by trapping of a solution of commercial mixture Phase 5 in a polymerizing ethyl-triethoxysilane. These films show sensible optical response to external electrical fields and temperature. Droplet sizes vary from ≈0.5 to 3 μm. The microdomain orientation is related to an ordering effect of the liquid crystal director produced by the ethyl groups at the walls of the pores. Reversible nematic liquid crystal ↔ isotropic liquid phase transitions are also observed by evolution of laser diffraction patterns and by heating in a microscope plate between crossed polarizers.

[1]  Sumio Sakka,et al.  Glasses from metal alcoholates , 1980 .

[2]  O. Lavrentovich,et al.  Self-organization of polymer dispersed nematic droplets , 1990 .

[3]  Yoshio Kobayashi,et al.  The high dispersion of organic dye into a transparent alumina film and its applications to photochemical and non-photochemical hole burnings☆ , 1989 .

[4]  L. Hench,et al.  The sol-gel process , 1990 .

[5]  J. W. Doane,et al.  Field controlled light scattering from nematic microdroplets , 1986 .

[6]  Youichi Kurokawa,et al.  Preparation of a transparent alumina film doped with organic dye by the sol-gel process , 1988 .

[7]  Claudio Rottman,et al.  Doped sol-gel glasses as chemical sensors , 1990 .

[8]  H. Namikawa,et al.  Photochemical hole‐burning study of 1,4‐dihydroxyanthraquinone doped in amorphous silica prepared by alcoholate method , 1985 .

[9]  Emil Wolf,et al.  Principles of Optics: Contents , 1999 .

[10]  D. Avnir,et al.  Applications of the sol-gel process for the preparation of photochromic information-recording materials: synthesis, properties, mechanisms , 1989 .

[11]  J. William Doane,et al.  Response times and voltages for PDLC light shutters , 1989 .

[12]  L. Blinov.  Electro-optical and Magneto-optical Properties of Liquid Crystals , 1983 .

[13]  New Non-Reorientational Optical Nonlinear Effect in MBBA , 1987 .

[14]  Paul S. Drzaic,et al.  Droplet shape and reorientation fields in nematic droplet/polymer films , 1989 .

[15]  C. Brinker.  Sol-gel science , 1990 .

[16]  G. Chidichimo,et al.  Electrooptic properties of polymer dispersed liquid crystals , 1989 .

[17]  Samo Kralj,et al.  Proton N.M.R. lineshape in nematic microdroplets , 1989 .

[18]  David Avnir,et al.  Biochemically active sol-gel glasses: The trapping of enzymes ☆ , 1990 .

[19]  Renata Reisfeld,et al.  The nature of the silica cage as reflected by spectral changes and enhanced photostability of trapped Rhodamine 6G , 1984 .

[20]  Optically Induced Reorientation in Nematic Cylindrical Structures , 1985 .

[21]  M. Yamane,et al.  Preparation of a gel from metal alkoxide and its properties as a precursor of oxide glass , 1978 .

[22]  P. Drzaic.  Polymer dispersed nematic liquid crystal for large area displays and light valves , 1986 .

[23]  David Avnir,et al.  Effects of the changes in the properties of silica cage along the gel/xerogel transition on the photochromic behavior of trapped spiropyrans , 1988 .

[24]  Bruce Dunn,et al.  Rigidochromism as a probe of gelation and densification of silicon and mixed aluminum-silicon alkoxides , 1989 .

[25]  Renata Reisfeld,et al.  Organic fluorescent dyes trapped in silica and silica-titania thin films by the sol-gel method: photophysical, film and cage properties , 1985 .

[26]  Yoshio Kobayashi,et al.  A transparent alumina film doped with laser dye and its emission properties , 1988 .

[27]  G. W. Gray.  Molecular structure and the properties of liquid crystals , 1962 .