Tailoring Heat Transfer at Silica-Water Interfaces via Hydroxyl and Methyl Surface Groups

TL;DR

This study uses molecular dynamics simulations to show how surface functionalization with hydroxyl and methyl groups on silica surfaces significantly affects wetting, adhesion, water molecule orientation, and heat transfer efficiency at the silica-water interface.

Contribution

It reveals how changing surface groups from methyl to hydroxyl enhances heat transfer and alters interfacial properties, providing a method to tailor thermal transport at solid-liquid interfaces.

Findings

Hydroxyl groups increase adhesion energy up to eightfold.

Surface functionalization influences water molecule orientation.

Manipulating functional group concentrations can tailor heat transfer.

Abstract

Efficient thermal transport across solid-liquid interfaces is essential for optimizing heat dissipation in modern technological applications. This study employs molecular dynamics (MD) simulations to investigate the impact of surface functionalization on heat transfer at the silica/water interface. It has been shown that the surface functionalization changes significantly the wetting characteristics of silica surface: from one hand hydroxyl groups render such surfaces more hydrophilic, while methyl groups more hydrophobic. Here, we reveal that modifying the surface functionalization from methylated to hydroxylated groups results in: (i) up to an approximately eightfold increase in adhesion energy, (ii) a reorientation of interfacial water molecules to align perpendicular to the surface normal, (iii) a reduction in the liquid depletion length near the interface, and (iv) an overall enhancement of interfacial heat conduction. We quantify interfacial thermal resistance through the calculation of the contribution of each functional group to the total heat flux, providing insights into the physical mechanisms governing heat transfer at functionalized interfaces. We demonstrated that manipulation of the concentrations of the functional groups can be used to tailor interfacial thermal transport.