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.