Texture transitions in binary mixtures of 6OBAC with compounds of its homologous series

TL;DR

This study investigates texture transitions in binary mixtures of 6OBAC with homologous series compounds, revealing persistent texture transitions in the nematic phase despite mixing-induced disorder.

Contribution

It demonstrates that texture transitions occur in binary mixtures of 6OBAC with other homologous compounds, extending understanding of phase behavior in liquid crystal mixtures.

Findings

Texture transitions are observed in binary mixtures despite microscopic disorder.

Binary mixtures show broadened smectic and nematic temperature ranges.

Texture transition temperature varies locally in mixtures with different chain lengths.

Abstract

Recently we have observed in compounds of the 4,n-alkyloxybenzoic acid series, with the homologous index n ranging from 6 to 9, a texture transition in the nematic range which subdivides the nematic phase in two sub-phases displaying different textures in polarised light analysis. To investigate a persistence of texture transitions in nematic phases, we prepared binary mixtures of 4,6-alkyloxybenzoic acid (6OBAC) with other members (7-,8-,9-,12-, 16OBAC) of its homologous series. Binary mixtures exhibit a broadening in the temperature ranges of both smectic and nematic phases. A nematic temperature range of 75 C is observed. In the nematic phase, in spite of the microscopic disorder introduced by mixing two components, the polarised light optics analysis of the liquid crystal cells reveals a texture transition. In the case of the binary mixture of 6OBAC with 12OBAC and with 16OBAC, that is of compounds with monomers of rather different lengths, the texture transition temperature is not homogeneous in the cell, probably due to a local variation in the relative concentrations of compounds.