Binary Mixtures of Polar Smectics A₁ with a Nematic Gap and Nematic Reentrant Phase

Abstract

Phase diagrams (T=f(x)) are determined for binary mixtures composed of p-alkoxybenzoyloxy-p'-cyanoazobenzenes (nOBCAB) and isothiocyanatophenyl 4-(trans-4n-alkylcyclohexyl) benzoates (nTPCHB). It is shown that in these mixtures the smectic phase of OBCAB is destabilized and a nematic gap, as well as the reentrant nematic phase appear. The generalized conclusion is drawn that such behaviour is typical for mixtures in which one of the components belongs to a homologous series whose members with shorter aliphatic chains reveal the smectic A₁ phase and those with longer chains the A_d one, and the other component is a smectic A₁ of lower polarity.