Molecular engineering of liquid crystal polymers by living polymerization. XXII. Synthesis and characterization of binary copolymers of 11-[4-cyano-4′-biphenyl)oxy]undecanyl vinyl ether with (2S, 3S)-(+)-2-chloro-3-methylpentyl 4′-(8-vinyloxyoctyloxy)biphenyl-4-carboxylate, and of (2S, 3S)-(+)-2-chloro-3-methylpentyl 4′-(8-vinyloxyoctyloxy)biphenyl-4-carboxylate with 3-[4-cyano-4′-biphenyl)oxy]propyl vinyl ether

Abstract

The synthesis and characterization of poly{11-[(4-cyano-4′-biphenyl)oxy]undecanyl vinyl ether-co-(2S, 3S)-(+)-2-chloro-3-methylpentyl 4′-(8-vinyloxyoctyloxy)biphenyl-4-carboxylate}X/Y {poly[(6–11)-co-(15–8)]X/Y} (where X/Y represents the molar ratio of the two structural units) and poly {(2S, 3S)-(+)-2-chloro-3-methylpentyl 4′-(8-vinyloxyoctyloxy)biphenyl-4-carboxylate-co-3-[(4-cyano-4′-biphenyl)oxy]propyl vinyl ether}X/Y poly[(15–8)-co-(6–3)]X/Y} with degree of polymerization of about 20 and molecular weight distribution of about 1·1 are described. The mesomorphic behaviour of all copolymers determined from both first, second and subsequent DSC scans was discussed as a function of composition. As determined from the second DSC scans, poly(6–11) exhibits enantiotropic smectic A (S_A) and S_X (unidentified smectic), poly(6–3) enantiotropic nematic, while poly(15–8) exhibits enantiotropic S_A, chiral smectic C (S_C*) and S_X (unidentified smectic) mesophases. Poly[(6–11)-co-(15–8)]X/Y exhibit a S_A phase over the entire range of compositions and a new induced S_X phase for X/Y = 8/2 to 4/6. The S_A phase displays a continuous dependence of copolymer composition with an upward curvature. Poly[(15–8)-co-(6–3)]X/Y with X/Y from 10/0 to 3/7 displays an enantiotropic S_A mesophase with an upward curvature as their highest phase, while those with X/Y from 2/8 to 1/9 an enantiotropic cholesteric mesophase.