Phase diagrams and mixing enthalpies of binary liquid‐crystalline systems exhibiting a semectic A phase

Abstract

The induced smectic A phase which appears in binary liquid crystalline systems has been investigated. Phase diagrams, clearing enthalpies, heat capacities and mixing enthalpies of two binary mixtures of a terminal polar component and of a weakly polar one are presented. The influence of the alkyl chain length, steric and EDA-type interactions on the formation of induced smectic A phase are discussed.Die induzierte smektische A Phase, die in binlren flussig-kristallinen Systemen auftritt, wurde untersucht. Phasendiagramme, Klarenthalpien, Warmekapazitaten und Mischungsenthalpien von zwei biniiren Mischungen einer polaren mit einer schwachen polaren Komponente werden vorgestellt. Der EinfluB der Alkylkettenlinge, der sterischen und EDA-Wechselwirkung auf die Bildung induzierter smektischer A Phasen wird diskutiert.

Phase diagrams of a binary smectic-A mixture

“…a temperature vs composition phase diagram for a mixture of two low molar mass liquid crystals ͑4-nitropentyl-4Ј octyloxybenzoate and 4-n-hexyloxyphenyl-4Ј-n-decyloxy-benzoate͒ 15,16 in comparison with the calculated coexistence curves for the nematic and induced smectic coexistence phase boundaries. The closed circles are the experimental data points 15,16 and the solid lines represent the calculated coexistence curves using T SN,1 ϭ61°C and T NI,1 ϭ68°C and T SN,2 ϭ83°C and T NI2 ϭ89°C of the constituents from the experiment. 16 The ␣ 1 and ␣ 2 values were computed to be ␣ 1 ϭ0.943 and ␣ 2 ϭ0.953, respectively.…”

“…The closed circles are the experimental data points 15,16 and the solid lines represent the calculated coexistence curves using T SN,1 ϭ61°C and T NI,1 ϭ68°C and T SN,2 ϭ83°C and T NI2 ϭ89°C of the constituents from the experiment. 16 The ␣ 1 and ␣ 2 values were computed to be ␣ 1 ϭ0.943 and ␣ 2 ϭ0.953, respectively. The composition of the azeotrope was estimated to be I AZ ϭ0.42 from the experimental phase diagram that in turn gives cϭ1.185, and thus the c parameter is no longer an adjustable parameter in the present case.…”

“…The predictive capability of the present combined FH/MSM model for determining the coexistence regions of the binary smectic-A mixture has been tested rigorously with the reported smectic phase diagram. 15,16…”