Nematic Bendsplay Elastisity of Cyanophenyl Compozmds with Different Terminal Groups

Abstract

The elastic properties of nematic compounds with terminal cyanoaromatic and containing cycles aliphatic groups were investigates. The terminal group structure has essential influence on the bend K3 and splay K1 elastic constants and their temperature dependences. The ninth and tenth members of 4-cyanophenyl 4′-n-alkyloxybenzoate series (nCPh) and cyanobiphenyl ether with ethylenebutylcyclohexane terminal group show pretransitional divergence of K3 in the vicinity of the nematic-smectic phase transition. Outside pretransitional temperature region the alternatation from odd to even n in nCPh series is accompanied by positive jumps of the K3/K1 and change of the character of its temperature dependence. A striking unmonotonous temperature dependence of the elastic splay constant K1 was founded for cyanobiphenyl ether with butylcyclohexane terminal group. The occurrence of frozen striped texture in a smectic phase after the nematic-smectic transition in the presence of magnetic field was found for all nematics with the temperature divergence of K3. Distance between stripes was the less, the More magnetic induction.