Anisotropic networks, elastomers and gels

Abstract

Anisotropic networks, elastomers and gels exhibit piezoelectric, pyroelectric, ferroelectric and NLO properties of potential interest for use in many electro-optic devices for optical communication and processing technologies. The formation, properties and applications of such anisotropic, mainly liquid crystalline, networks are described. If some of the molecules in a liquid mixture contain at least two reactive groups which can be either photochemically or thermally polymerized, then crosslinked, anisotropic networks, elastomers and gels can be produced. Solid macroscopically aligned elastomers or networks can be formed as required beforehand or simultaneously by orientation of the sample. Anisotropic gels consist of a solid anisotropic network and non-covalently bonded, but strongly oriented domains of low molar mass liquid crystals. Anisotropic networks, elastomers and gels can be prepared from preformed amorphous or liquid crystalline polymers incorporating additional reactive groups, which can be macroscopically oriented in the liquid crystalline state and then ® xed by additional crosslinking reactions. Reversible networks, elastomers and gels can be prepared either non-covalently or covalently by thermally reversible linkages between, for example, side group polymers and low molar mass molecules, neither of which necessarily exhibit liquid crystalline properties in the pure state.

Bioinspired underwater locomotion of light-driven liquid crystal gels

“…We postulate that anisotropic plasticized LCNs (i.e., LCGs) can alleviate these problems. Previously, the electro-optical behavior of these materials in confined geometries has been extensively studied (43)(44)(45), and a few reports have focused on their potential as free-standing actuators (23,46,47). In LCGs, the LC molecules and cross-linked networks self-assemble into nanoscale composites with a highly coupled thermomechanical response (44).…”

Morphological studies of a hydrogen-bonded LC polymer obtained by photopolymerization in LC solvents

“…Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions 1. Introduction LC polymer networks or LC elastomers have attracted considerable attention because of their unique properties [1][2][3][4]. Of particular interest are non-display applications such as second harmonic generation [5,6], piezoelectricity [7,8], electrostriction [9], as tunable laser sources [10], and thermally stimulated anisotropic deformation [11,12].…”

Anisotropic network formation by the photopolymerization of new monomers derived from 4‐hydroxybenzenethiol

“…However, most reported liquid-crystal monomers exhibit a mesophase at high temperatures, and this hinders the preparation of films. 14 Here we describe the synthesis, thermotropic properties, and photoinitiated polymerization of liquidcrystal diacrylates under UV light for the preparation of anisotropic networks. Moreover, the dichroic ratio for specific groups of the networks were determined with FTIR linear dichroism.…”