Pressurized liquid in nanopores: a modified Laplace-Young equation.

Abstract

In the current study, we analyze the motion of pressurized water molecules in nanopores of a well-crystallized, hydrophobic zeolite using both experiment and molecular dynamics simulation. It is discovered that, contradictory to the prediction of the classic Laplace-Young equation, the required infiltration pressure is highly dependent on the infiltration volume. A modified Laplace-Young equation is developed to take into consideration the effective solid-liquid interfacial tension, the thermal energy exchange, as well as the variation in configuration of confined liquid molecules. The last two factors are significant only when the nanopore diameter is comparable with the liquid molecule size. It is also remarkable that the infiltrated liquid molecules, when confined in the nanoenvironment, could transform from a single-chain conformation to a double-helical structure as the pressure increases, accompanied by an abrupt system free energy change that leads to different pressure-induced transport behaviors.