Depletion-driven four-phase coexistences in discotic systems

Abstract

Free volume theory (FVT) is a versatile and tractable framework to predict the phase behaviour of mixtures of platelets and non-adsorbing polymer chains in a common solvent. Within FVT, three principal reference phases for the hard platelets are considered: isotropic (I), nematic (N), and columnar (C). We derive analytical expressions that enable us to systematically trace the different types of phase coexistences revealed upon adding depletants and confirm the predictive power of FVT by testing the calculated diagrams against phase stability scenarios from computer simulation. A wide range of \textit{multi}-phase equilibria is revealed, involving two-phase isostructural transitions of all phase symmetries (INC) considered as well as the possible three-phase coexistences. Moreover, we identify the system parameters, relative disk shapes and colloid-polymer size ratios, at which four-phase equilibria are expected. These involve a remarkable coexistence of all three phase states commonly encountered in discotics including isostructural coexistences I${}_1$-I${}_2$-N-C, I-N${}_1$-N${}_2$-C, and I-N-C${}_1$-C${}_2$.

23 pages, 9 figures, Molecular Physics, Frenkel Special Issue (2018)

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Cited by in corpus (7)

• Defying the Gibbs Phase Rule: Evidence for an Entropy-Driven Quintuple Point in Colloid-Polymer Mixtures
• Gravity-induced phase phenomena in plate-rod colloidal mixtures
• Algebraic equations of state for the liquid crystalline phase behavior of hard rods
• Phase Behaviour of Binary Hard-Sphere Mixtures: Free Volume Theory Including Reservoir Hard-Core Interactions
• Sedimentation of colloidal plate-sphere mixtures and inference of particle characteristics from stacking sequences
• Self-assembly and entropic effects in pear-shaped colloid systems: I. Shape sensitivity of bilayer phases in colloidal pear-shaped particle systems
• Self-assembly and entropic effects in pear-shaped colloid systems: II. Depletion attraction of pear-shaped particles in a hard sphere solvent