Smectic-A and Smectic-C Phases and Phase Transitions in Liquid Crystal-Aerosil Gels

TL;DR

This study investigates how aerosil gel networks influence phase transitions in a specific liquid crystal, revealing significant disorder effects and altered transition behaviors.

Contribution

It provides detailed experimental insights into the effects of aerosil-induced disorder on smectic phase transitions in liquid crystals.

Findings

Aerosil gel significantly alters nematic to Smectic-A transition.

The Smectic-A to Smectic-C transition is fundamentally changed by aerosil.

Correlation lengths follow a power-law dependence on aerosil density.

Abstract

High-resolution X-ray scattering studies of the nonpolar thermotropic liquid crystal 4-n-pentylphenylthiol-4'-n-octyloxybenzoate (\bar{8}S5) in aerosil gel nano-networks reveal that the aerosil-induced disorder significantly alters both the nematic to Smectic-A and Smectic-A to Smectic-C phase transitions. The limiting Smectic-A correlation length follows a power-law dependence on the aerosil density in quantitative agreement with the limiting lengths measured previously in other Smectic-A liquid crystal gels. The Smectic-A to Smectic-C liquid crystalline phase transition is altered fundamentally by the presence of the aerosil gel. The onset of the Smectic-C phase remains relatively sharp but there is an extended coexistence region where Smectic-A and Smectic-C domains can exist.