Molecular engineering of liquid-crystalline polymers by living polymerization. Part 13.—Synthesis and living cationic polymerization of (S)-(–)-2-methylbutyl 4′-(ω-vinyloxy)alkoxybiphenyl-4-carboxylate with undecanyl and hexyl alkyl groups

Abstract

The synthesis and living cationic polymerization of (S)-(–)-2-methylbutyl 4′-(11-vinyloxy)undecyloxybiphenyl-4-carboxylate (13–11) and (S)-(–)-2-methylbutyl 4′-(6-vinyloxy)hexyloxybiphenyl-4-carboxylate (13–6) are described. Polymers with degrees of polymerization from 4 to 26 and polydispersities ⩽ 1.10 were synthesized and characterized by differential scanning calorimetry (DSC) and thermal optical polarized microscopy. When determined from first heating and cooling DSC scans, poly(13–11) exhibits monotropic s_A, s_C* and s_X(unidentified) mesophases over the entire range of molecular weights. When determined from second and subsequent heating and first and subsequent cooling scans, poly(13–11) with degrees of polymerization ⩽ 10 exhibit enantiotropic s_A, s_C* and s_X mesophases, and crystallization on the heating scan, while those with higher degrees of polymerization exhibit enantiotropic s_A, s_C* and s_X mesophases only. Regardless of the thermal history of the sample, poly(13–16) exhibits an enantiotropic s_A phase, and the polymers with degrees of polymerization > 12 exhibit an enantiotropic s_X mesophase as well.