화학공학소재연구정보센터
Journal of the American Chemical Society, Vol.122, No.8, 1593-1601, 2000
Molecular design of nonchiral bent-core liquid crystals with antiferroelectric properties
Novel bent-core (banana-shaped) liquid crystals without Schiff-base units have been synthesized and investigated by polarized light optical microscopy, differential scanning calorimetry, X-ray scattering, and electrooptical investigations. These molecules are 4-(4-alkylbenzoyloxy)benzoates and 4-(4-alkoxybenzoyloxy)benzoates of resorcinol, 3,4'-dihydroxybiphenyl, and 4,4"-dihydroxy-1,1':3',1"-terphenyl. Three different mesophases were found depending on the molecular structure and the length of the terminal alkyl chains: a rectangular columnar phase, a highly ordered low-temperature mesophase, and an antiferroelectric switchable fluid smectic mesophase designated as SmCPA. The influence of the molecular structure on the occurrence of the SmCPA phase was investigated. The spontaneous polarization of these molecules is quite high (P-S = 500-700 nC cm(-2)) and specially those molecules with long alkyl chains and short bent-core structures have low melting points and broad regions of this switchable mesophase. Furthermore, first examples of antiferroelectric switchable bent-core molecules with semifluorinated terminal chains will be described.