Rebound Suppression of a Droplet Impacting on a Supersolvophobic Surface by a Small Amount of Polymer Additives

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 multibody dissipative particle dynamics simulations. Either the long 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 the 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.