Towards the description of water adsorption in slit-like nanochannels with grafted molecular brushes. Density functional theory

TL;DR

This study uses density functional theory to analyze how water adsorbs in nanochannels with grafted polymer brushes, focusing on the effects of grafting density and temperature on brush structure and water interface properties.

Contribution

It introduces a theoretical model combining density functional theory with a pearl-necklace polymer brush model to study water adsorption in nanochannels.

Findings

Polymer brush height depends on grafting density.

Interface structure varies with temperature and grafting density.

Brushes exhibit shrinking and swelling behavior upon adsorption.

Abstract

We have explored a model for adsorption of water into slit-like nanochannels with two walls chemically modified by grafted polymer layers forming brushes. A version of density functional method is used as theoretical tools. The water-like fluid model adopted from the work of Clark et al. [Mol. Phys., 2006, 104, 3561] adequately reproduces the bulk vapour-liquid coexistence envelope. The polymer layer consists of chain molecules in the framework of pearl-necklace model. Each chain molecule is chemically bonded to the pore walls by a single terminating segment. Our principal focus is in the study of the dependence of polymer layer height on grafting density and in the microscopic structure of the interface between adsorbed fluid and brushes. Thermal response of these properties upon adsorption is investigated in detail. The results are of importance to understand shrinking and swelling of the molecular brushes in the nanochannels.