Rebound suppression of a droplet impact on a supersolvophobic surface by a small amount of polymer additives

TL;DR

This study uses simulations to show that small amounts of polymer additives can suppress droplet rebound on supersolvophobic surfaces through mechanisms involving polymer elongation and surface wettability changes.

Contribution

It reveals a new anti-rebound mechanism and quantifies how polymer molecular weight and concentration influence droplet impact dynamics.

Findings

Polymer additives suppress droplet rebound without changing shear viscosity.

Longer polymers and higher concentrations increase rebound suppression.

Polymer adsorption and elongation force are key to anti-rebound effects.

Abstract

A small amount of polymer dissolved in a droplet suppresses droplet rebound when it impinges on a supersolvophobic surface. This work investigates impacting dynamics of a droplet of dilute polymer solution depending on the molecular weight and the concentration of the polymer by using multi-body dissipative particle dynamics simulations. Either the longer polymer or the high polymer concentration suppresses rebound of a droplet although its shear viscosity and the liquid-vapor surface tension are not different from those of a pure solvent droplet. We found a new mechanism of the anti-rebound in which the resistance is applied against the hopping motion, while behavior of the non-rebounding droplet at the earlier spreading and retraction stages is same as for the rebounding droplets. Two polymer contributions to reducing the rebound tendency are quantitatively analyzed: the alteration of the substrate wettability by the polymer adsorption and the polymer elongation force.