Journal of Polymer Science Part A: Polymer Chemistry, Vol.38, No.19, 3631-3655, 2000
Chiral recognition in molecular and macromolecular pairs of (S)- and (R)-1-cyano-2-methylpropyl-4 '-{[4-(8-vinyloxyoctyloxy)benzoyl]oxy}biphenyl-4-carboxylate enantiomers
(S)-1-Cyano-2-methylpropyl-4'-{[4-(8-vinyloxyoctyloxy)benzoyl]oxy}biphenyl-4-carboxylate [(S)-11] and (R)-1-cyano-2-methylpropyl-4'-{[4-(8-vinyloxyoctyloxy)benzoyl] oxy}biphenyl-4-carboxylate [(R)-11] enantiomers, both greater than 99% enantiomeric excess, and their corresponding homopolymers, poly[(S)-11] and poly[(R)-11], with well-defined molecular weights and narrow molecular weight distributions were synthesized and characterized. The mesomorphic behaviors of (S)-11 and poly[(S)-11] are identical to those of (R)-11 and poly[(R)-11], respectively. Both (S)-11 and (R)-11 exhibit enantiotropic S-A, S*(C), and S-X (unidentified smectic) phases. The corresponding homopolymers exhibit S-A and S*(C) phases. The homopolymers with a degree of polymerization (DP) less than 6 also show a crystalline phase, whereas those with a DP greater than 10 exhibit a second S-X phase. Phase diagrams were investigated for four different pairs of enantiomers, (S)-11/(R)-11, (S)-11/poly[(R)-11], and poly[(S)-11]/poly[(R)-11], with similar and dissimilar molecular weights. In all cases, the structural units derived from the enantiomeric components are miscible and, therefore, isomorphic in the S-A and S*(C) phases over the entire range of enantiomeric composition. Chiral molecular recognition was observed in the S-A and S-X phases of the monomers but not in the S-A phase of the polymers. In addition, a very unusual chiral molecular recognition effect was detected in the S*(C) phase of the monomers below their crystallization temperature and in the S*(C) phase of the polymers below their glass-transition temperature. In the S*(C) phase of the monomers above the melting temperature and of the polymers above the glass-transition temperature, nonideal solution behavior was observed. However, in the S-A phase the monomer-polymer and polymer-polymer mixtures behave as an ideal solution.