Capillary and anchoring effects in thin hybrid nematic films and connection with bulk behavior

TL;DR

This paper investigates how capillary and anchoring effects influence the behavior of thin hybrid nematic films, revealing complex phase transitions and their connection to bulk properties using a molecular model.

Contribution

It introduces a detailed analysis of hybrid nematic films with antagonistic anchoring, highlighting the interaction between anchoring transitions and capillary isotropic-nematic transitions.

Findings

Existence of step-tilt, biaxial phase and transition to linear tilt configuration.

Connection of step-like phase with bulk isotropic phase as film thickness increases.

Proposal of possible global surface phase diagrams.

Abstract

By means of a molecular model, we examine hybrid nematic films with antagonistic anchoring angles where one of the surfaces is in the strong anchoring regime. If anchoring at the other surface is weak, and in the absence of wetting by the isotropic phase, the anchoring transition may interact with the capillary isotropic-nematic transition in interesting ways. For general anchoring conditions on this surface we confirm the existence of the step-tilt, biaxial phase and the associated transition to the linear, constant-tilt-rotation, configuration. The step-like phase is connected with the bulk isotropic phase for increasing film thickness so that the latter transition is to be interpreted as the capillary isotropic-nematic transition. Finally, we suggest possible global surface phase diagrams.