Effect of polydispersity and soft interactions on the nematic versus smectic phase stability in platelet suspensions

摘要: We theoretically discuss, using density-functional theory, the phase stability of nematic and smectic ordering in a suspension platelets same thickness but with high polydispersity diameter, study influence on this stability. The are assumed to interact like hard objects, additional soft attractive repulsive interactions, meant represent effect depletion interactions due addition nonabsorbing polymer, or screened Coulomb between charged an aqueous solvent, respectively, also considered. aspect (diameter-to-thickness) ratio is taken be very high, order model solutions mineral recently explored experimentally. In regime degree orientational occurs; therefore, can as completely parallel amenable analysis via fundamental-measure theory. Our focus versus interplay, since diameter suppresses formation columnar phase. When purely hard, theory predicts continuous nematic-to-smectic transition, regardless polydispersity. However, enhances against Predictions for case where interaction added obtained mean-field perturbation one-component fluid, transition remains forces, becomes more stable range decreased. opposite behavior respect observed fact first below tricritical point. Also, demixing appears, associated critical platelet introduced temperature shifts values.