Structure of solution of colloid and hydrogen bonding fluid near a semipermeable membrane

Abstract

The local fluid structure of a solution consisting of colloid particles and hydrogen bonding(HB) fluid se-parated from pure solvent by a semipermeable membrane was investigated, where the colloid particles and HB fluid serve as solute and solvent, respectively. In this paper, the semipermeable membrane allows the passage of solvent molecules but not solute particles, and therefore, it provides a nano-confinement for colloid particles. The density profiles of the two species near the semipermeable membrane were determined via density functional theory(DFT) for classical fluids. Based on the predicted density profiles under various conditions, the effects of HB strength, func-tionality, total bulk density, density fraction and the size ratio of two species on the fluid structure were discussed. As an application, the osmotic pressures of the system were also presented. It is shown that the local structure and osmotic pressure can be efficiently regulated by these factors due to the competition between the excluded volume interactions and the HB interaction. The present results are expected to be helpful to study the osmotic phenomena and relevant problems on the nanoscale.