Phase transitions in nanoconfined fluids: Synergistic coupling between soft and hard matter

Abstract

We report recent theoretical developments in the study of gas-liquid transitions of fluids confined to deformable mesoporous materials. Due to a synergistic coupling the phase behavior of the confined soft matter phase is significantly affected by the deformation of the confining material which in turn is deformed as a result of phase changes occurring in the confined phase. If the confined fluid is gas-like its wetting characteristics affect the strain isotherm such that the pore may expand or contract as more gas is adsorbed prior to capillary condensation. Directly at capillary condensation the pore abruptly shrinks on account of fluid-substrate attraction. If the density of the confined liquid-like phase is then enhanced further the pore expands again. This expansion allows one to determine nanomechanical properties of the confining solid directly from the deformation isotherm. In the future it might be possible to fabricate sensors that allow one to measure mechanically changes in thermodynamic properties of confined soft matter phases.