The Emergent Nematic Phase in Ionic Chromonic Liquid Crystals

Chromonic liquid crystals exhibit a unique self-assembly process which is of both theoretical and practical interest. A characteristic feature of chromonics is the occurrence of molecular association through stacking at extremely low concentrations. Experimental evidence has suggested that this process is approximately isodesmic across a broad concentration range. Another important aspect of these phases is a separation of energy scales for elastic deformation that leads to novel bulk morphologies and defect arrangements. To date, only a handful of computational studies have managed to reproduce crucial aspects of chromonic phases, with ionic chromonics treated only by expensive fully atomistic simulations. Here, we present a simple model based on the competition between long-range repulsions and short-range anisotropic attractions capable of capturing all features of the chromonic phase. Molecular simulations of coarse-grained mesogens are used to map out the phase behavior and explore how structural and energetic anisotropies influence their ordering and response. This work presents the first computational investigation into the nematic elasticity of these phases and demonstrates key correlations between elastic response and stack growth.