Luminescent mesogen jacketed poly(1-alkyne) bearing lateral terphenyl with hexyloxy tail

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Abstract

Mesogen jacketed liquid crystalline poly(1-alkyne) and poly(1-phenyl-1-alkyne) linked pendants of terphenyl mesogens with hexyloxy tails at the waist position ([BOND]{RC[DOUBLE BOND]C[BOND] [(CH2)3OOC-terpheyl-(OC6H13)2]}n[BOND], where R[DOUBLE BOND]H, PHATP(OC6)2; R[DOUBLE BOND]C6H5, PPATP(OC6)2) were synthesized. The influences of structural variations on the thermal, mesomorphic, and luminescent properties were investigated. Polymerizations of all monomers are carried out by WCl6-Ph4Sn catalysts successfully. The polymers are stable (Td ≥ 340 °C) and soluble in common solvents. The monomers and polymers show enantiotropic SmA phases in the heating and cooling processes, and the lateral side chains of the mesogenic units are perpendicular to the main chain. The “jacket effect” of chromophoric terphenyl core “shell” around the main chain also contributes to polymers with high photoluminescence, and the pendant-to-backbone energy transfer path is involved in the luminescence process of this polymers. In comparison with monosubstituted polyacetylene PHATP(OC6)2, the disubstituted polyacetylene PPATP(OC6)2 shows better photoluminescence in both THF solution and film, and exhibited about 40 nm red-shifted than PHATP(OC6)2, indicating that the “jacket effect” of terphenyl mesogens forces poly(1-phenyl-1-alkyne) backbone to extend in a more planar conformation with a better conjugation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

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