Stick-jump mode in surface droplet dissolution

TL;DR

This paper introduces and analyzes a new stick-jump dissolution mode for small surface droplets, supported by experiments and theory, expanding understanding of droplet evaporation behaviors.

Contribution

It identifies and characterizes the novel stick-jump mode in droplet dissolution, providing experimental evidence and theoretical predictions for this previously unrecognized behavior.

Findings

Discovery of the stick-jump mode in small droplets

Experimental validation of the mode's occurrence

Theoretical prediction of dissolution times in this mode

Abstract

The analogy between evaporating surface droplets in air to dissolving long-chain alcohol droplets in water is worked out. We show that next to the three known modi for surface droplet evaporation or dissolution (constant contact angle mode, constant contact radius mode, and stick-slide mode), a fourth mode exists for small droplets on supposedly smooth substrates, namely the stick-jump mode: intermittent contact line pinning causes the droplet to switch between sticking and jumping during the dissolution. We present experimental data and compare them to theory to predict the dissolution time in this stick-jump mode. We also explain why these jumps were easily observed for microscale droplets but not for larger droplets.