Side chain liquid crystalline polymers containing siloxane spacer: 7. Syntheses and properties of polyimides and polyamides containing a mesogenic side chain connected with a disiloxane linkage

Abstract

Preparations of polyimides and polyamides containing a mesogenic group in the side chain connected with a siloxane bond in the spacer component were carried out. A 3,5-diaminobenzyloxy-type monomer having a mesogen consisting of a p'-substituted biphenyl benzoate group was prepared by means of hydrosilylation of 1-[3-43,5-dinitrobenzyloxy)propyl]-1,1,3,3-tetramethyldisiloxane with a mesogenic allyloxy compound, followed by catalytic reduction of the two nitro groups. The polyimides were synthesized by polycondensation of the diamine monomers with 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), followed by chemical imidization. The polyamides were also synthesized by polycondensation of the diamine monomers with dicarboxylic dichloride compounds, i.e., terephthaloyl dichloride, oxalyl dichloride, malonyl dichlonride, succinyl dichloride, glutaryI dichloride, adipoyl dichloride, pimeloyI dichloride and azelaoyl dichloride. The structural effects on the thermal properties of the polymers were investigated. The obtained polyamides having an aliphatic group in the main chain exhibited an enantiotropic smectic mesophase at around 100-150C, while no mesophase was observed for the polyimides and a polyamide having an aromatic backbone.

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