Dimerization of polar smectics A₁ with a terminal cyano group in the matrix of smectics A₁ of lower polarity

Abstract

Binary mixtures have been studied of polar compounds with smectic A₁ phases belonging to the following series: 4-cyanobiphenyl 4-yl 4′-n-alkylbiphenyl-4-carboxylate (CBnAB) and 4-(trans-4-n-decylcyclohexyl) benzoates (10XPCHB) with X = F, NCS, COCH₃. In these systems a strong destablization of the smectic A₁ phase is observed on the side of the CBnAB component and an enhancement of the smectic A₁ phase on the side of 10XPCHB. It is shown that the anomalous behaviour of the mixtures of two A₁ smectics with a similar layer spacing is due to the dimerization of CBnAB in the matrix of 10XPCHB which is of lower polarity.