The influence of van der Waals forces on droplet morphological transitions and solvation forces in nanochannels

TL;DR

This paper investigates how van der Waals forces influence droplet shape transitions and solvation forces in nanochannels, revealing the effects of microscopic interactions on macroscopic behavior.

Contribution

It introduces a mesoscopic approach incorporating van der Waals forces via an effective interface potential to analyze droplet morphology and solvation forces in nanochannels.

Findings

Contact angle depends on droplet volume and channel width.

Droplet shape transition occurs with increasing volume.

Solvation force can be attractive or repulsive depending on channel width.

Abstract

The morphological phase transition between a sessile and lenticular shapes of a droplet placed in a nanochannel is observed upon increasing the droplet volume. The phase diagram for this system is discussed within the macro- and mesoscopic approaches. On the mesoscopic level, the van der Waals forces are taken into account via the effective interface potential acting between the channel walls and the droplet. We discuss the contact angle dependence on the droplet volume and the distance between the walls; this angle turns out to be smaller than the macroscopic Young's angle. The droplet presence induces the solvation force acting between the channel walls. It can be both attractive and repulsive, depending on the width of the channel.