Molecular engineering of liquid-crystalline polymers by living polymerization. Part 18.—Sc* Mesophase in copolymers of (2S, 3S)-(+)-2-chloro-3-methylpentyl 4′-(ω-vinyloxyalkoxy)biphenyl-4-carboxylate with undecanyl and octyl alkyl groups

Abstract

The synthesis and living cationic polymerization of (2S, 3S)-(+)-2-chloro-3-methylpentyl 4′-(11-vinyloxyundecanyl-oxy)biphenyl-4-carboxylate (15-11) and (2S, 3S)-(+)-2-chloro-3-methylpentyl 4′-(8-vinyloxyoctyloxy)biphenyl-4-carboxylate (15-8) have been described. Poly(15-11)s and poly(15-8)s with degrees of polymerization (DP) up to 25 and polydispersities lower than 1.15 were synthesized and characterized by differential scanning calorimetry (DSC) and thermal optical polarized microscopy. Over the entire range of molecular weights poly(15-11)s and poly(15-8)s exhibit enantiotropic smectic A (SA) and chiral smectic C (SC*) mesophases. In addition, all poly(15-11)s exhibit a crystalline phase. Poly(15-8)s are non-crystallizable. However, poly(15-8)s with a DP higher than 12 exhibit an unidentified Sx mesophase. Poly(15-11-co-15-8)X/Y( where X/Y represents the molar ratio of monomer 15-11 to monomer 15-8) with DP of ca. 15 and polydispersities lower than 1.11 were also synthesized and characterized. Both the SA and SC* mesophases of these copolymers exhibit continuous dependences of composition.