# Phase separation and folding in swelled nematoelastic films

## TL;DR

This paper investigates how nematoelastic films deform and fold when exposed to an isotropic solvent, focusing on phase boundaries, shape changes, and hierarchical folding patterns in different geometries.

## Contribution

It introduces a model for the interphase boundary structure and computes equilibrium shapes and folding patterns in swelled nematoelastic films.

## Key findings

- Boundary structure influences line tension and shape deformation.
- Folding patterns emerge near phase boundaries due to differential expansion.
- Hierarchical folding is most prominent on cylindrical shells.

## Abstract

We explore reshaping of nematoelastic films upon imbibing an isotropic solvent under conditions when isotropic and nematic phases coexist. The structure of the interphase boundary is computed taken into account the optimal nematic orientation governed by interaction of gradients of the nematic order parameter and solvent concentration. This structure determines the effective line tension of the boundary. We further compute equilibrium shapes of deformed thin sheets and cylindrical and spherical shells with the rectilinear or circular shape of the boundary between nematic and isotropic domains. A differential expansion or contraction near this boundary generates a folding pattern spreading out into the bulk of both phases. The hierarchical ordering of this pattern is most pronounced on a cylindrical shell.