Texture transitions in the liquid crystalline alkyloxybenzoic acid 6OBAC

TL;DR

This study investigates the complex texture transitions in the liquid crystalline compound 6OBAC, revealing a unique nematic sub-phase transition originating directly from a crystal phase through image processing techniques.

Contribution

It is the first to demonstrate texture transitions in a nematic phase directly from a crystal phase in 6OBAC using image processing.

Findings

Identification of two nematic sub-phases with different textures.

First observation of a texture transition from crystal to nematic phase.

Application of image processing to distinguish crystal and nematic textures.

Abstract

The 4,n-alkyloxybenzoic acid 6OBAC has a very rich variety of crystalline structures and two nematic sub-phases, characterised by different textures. It is a material belonging to a family of liquid crystals formed by hydrogen bonded molecules, the 4,n-alkyloxybenzoic acids indicates the homologue number). The homologues with n ranging from 7 to 13 display both smectic C and N phases. In spite of the absence of a smectic phase, 6OBAC exhibits two sub-phases with different textures, as it happens in other materials of the homologue series which possess the smectic phase. This is the first material that exhibits a texture transition in a nematic phase directly originated from a crystal phase. Here we present the results of an image processing assisted optical investigation to characterise the textures and the transitions between textures. This processing is necessary to discriminate between crystal modifications and nematic sub-phases.