Structural and textural diversity during phase separation of binary mixtures of smectic and isotropic fluids

Phase separation due to thermally induced demixing in multicomponent liquid-liquid systems is a near-ubiquitous phenomenon; the same can be said regarding precipitation of solids from solution, whether as crystalline or amorphous materials. Here, we explore an intermediate scenario that has been little studied to date. We examine the demixing of structured fluids, liquid crystals, in binary mixtures with solvents. Simple binary mixtures of a smectic-forming mesogen with a long-chain aliphatic solvent show remarkable diversity in phase-separated structures. The structures result from the interplay among interfacial tension, mesogen anchoring, viscosity, and mesophase elasticity, which are parameterized by the composition and temperature of the system. We show that various morphologies can result, including thread-like LC filaments, singly- and doubly-twisted threads, and nematic or smectic droplets with associated defect textures. These results highlight the rich diversity of end-states that are accessible due to the combination of structural anisotropy and fluidity of the LC component.