Novel Phenylthiophene Rod-coil Block The Synthesis Of The Liquid Crystal Molecules And Performance Studies

Liquid crystals (LCs) combine order and mobility at a molecular level so that systems can take the lowest energy conformation in response to external (magnetic, electric field, chemical and mechanical) stimuli. Liquid crystals can exhibit excellent properties in many ways. The development of novel supramolecular materials with nanometer-scale architectures and the effect of these architectures on the materials'properties are currently of great interest in molecular design. Liquid crystalline assemblies of Rod-coil tri-block copolymer containing rigid rod segment and flexible coils (rod-coil molecules) provide a rich variety of different liquid crystalline structures of nanoscale dimensions. The change of hydrophobic forces, block volume fraction, molecular shape, and molecular length can have influence on the liquid crystalline behavior of dissymmetrical ABC (Coil-Rod-Coil), asymmetrical ABA (Coil-Rod-Coil) and BAB (Rod-Coil-Rod) tri-block copolymers. The unconventional mesophases are introduced; include smectic,2D columnar,3D cubic and tetragonal phases.In this thesis novel rod-coil triblock amphiphilic molecules consisting of a rigid 2-phenylthiophene core, with a polar flexible tri(oxylethylene) moieties coil attached to the phenyl ring and one or two alkyl chains attached to the thiophene ring at the other side have been synthesized by using Ni(II) and Pd(0) catalyzed coupling reaction as key steps. The tri (oxylethylene) moieties were terminated with hydroxyl group or polymerizable acryl group which allowing the rod-coil monomers to polymerize into side chain polymers, or sodium carboxylate group. The thermotropic and solvent induced liquid crystalline behavior of these compounds was investigated by polarized optical microscopy. Thereby the influence of the length and the number of the alkyl chains as well as the influence of the terminal groups attached on the tri (oxylethylene) moities in the mesophase behavior were investigated. Rod coil side chain polymers and sodium carboxylate trioxaether derivatives with one alkyl chain or cyano substituent formed smecticA phases; Sodium carboxylate trioxaether derivative with two adjacent long alkyl chains has thermotropic columnar mesophases. LC phase can be induced and stabilized by adding water in these Liquid crystals molecules. While UV and PL have been determined in these Liquid crystals molecules.The intential application of these compounds as elecroopticle materials are predicted.