Exploring the cylindrical photo-bending shape in polydomain nematic glass

TL;DR

This paper investigates how polarized light induces various bending shapes in polydomain nematic glass, explaining experimental phenomena and predicting conditions for cylindrical and other shapes based on material parameters.

Contribution

It introduces a homogenized model for photo-induced deformation in polydomain nematic glass, explaining the formation of cylindrical and other bending shapes under polarized light.

Findings

Cylindrical bending occurs under specific illumination conditions.

Bending shapes depend on Poisson ratio and light intensity.

The model predicts multiple possible shapes in a parameter space.

Abstract

This paper explores different photo-bending shapes in polydomain nematic glass. The motivation is to explain the phenomenon in experiment [1] under polarized light in which a nematic film curls into an circular arc, like part of a cylindrical surface. Polarized light triggers photo-isomerization and therefore makes liquid crystals (LCs) contract along their directors. We apply the Sachs limit to homogenize the deformation of polydomain LC glass. Photo-strain can be either contraction or expansion through the material. Bending shapes can be anticlastic, bowl-shaped and cylindrical affected by Poisson ratio and illumination intensity. An explanation for the cylindrical bend and ways to observe other shapes are given in a parameter plane.