Simulation study of the link between molecular association and reentrant miscibility for a mixture of molecules with directional interactions

The reentrant liquid-liquid miscibility of a symmetrical mixture with highl y directional bonding interactions is studied by Gibbs ensemble Monte Carlo simulation. The resulting closed loop of immiscibility and the correspondi ng lower critical solution temperature are shown to be a direct consequence of the dramatic increase in association between unlike components as the t emperature is lowered. Our exact calculations for an off-lattice system wit h a well-defined anisotropic potential confirm the findings of previous the oretical studies.