Mixtures of blue phase liquid crystal with simple liquids: elastic emulsions and cubic fluid cylinders

TL;DR

This paper numerically studies a mixture of blue phase I liquid crystal and isotropic fluid, revealing how interfacial and elastic forces influence morphology, including cubic fluid cylinders and emulsion droplets, with external electric field control.

Contribution

It introduces a detailed numerical analysis of phase separation in blue phase liquid crystals with simple fluids, highlighting morphology control via an inverse capillary number and electric fields.

Findings

Low $oldsymbol{ extit{ ext{chi}}}$ and concentration produce cubic fluid cylinders.

Higher $oldsymbol{ extit{ ext{chi}}}$ leads to slow-coarsening emulsion droplets.

Electric fields can switch between different cubic fluid cylinder phases.

Abstract

We investigate numerically the behaviour of a phase-separating mixture of a blue phase I liquid crystal with an isotropic fluid. The resulting morphology is primarily controlled by an inverse capillary number, $\chi$, setting the balance between interfacial and elastic forces. When $\chi$ and the concentration of the isotropic component are both low, the blue phase disclination lattice templates a cubic array of fluid cylinders. For larger $\chi$, the isotropic phase arranges primarily into liquid emulsion droplets which coarsen very slowly, rewiring the blue phase disclination lines into an amorphous elastic network. Our blue phase/simple fluid composites can be externally manipulated: an electric field can trigger a morphological transition between cubic fluid cylinder phases with different topologies.