Phenomenological Model of Wetting Charged Dielectric Surfaces and its Testing with Plasma-Treated Polymer Films and Inflatable Balloons

TL;DR

This paper presents a phenomenological model linking electrical charge density on plasma-treated polymer surfaces to their wetting behavior, supported by experiments on polymer films and inflatable balloons.

Contribution

It introduces a new theory connecting surface charge density to contact angle changes and validates it through experiments with plasma-treated polymers and balloons.

Findings

Charge density influences wetting regime transitions.

Surface charge leakage correlates with hydrophobic recovery.

Plasma treatment enhances surface energy and wettability.

Abstract

Plasma treatment of polymer films results in their electrical charging, which in turn gives rise to an increase in their surface energy. The process results in pronounced hydrophilization of the polymer surfaces. A phenomenological theory relating the change in the apparent contact angle of charged solids to the surface density of the electrical charge is introduced. Partial wetting, inherent for polymer films, becomes possible until the threshold surface density of the electrical charge is gained. The predictions of the theory are illustrated by plasma-treated polymer films and inflatable latex balloons. Deflating the plasma treated latex balloons resulted in an essential increase in the surface charge density of the latex. This increase switched the wetting regime from partial to complete wetting. The kinetics of hydrophobic recovery follows the kinetics of the electrical charge leakage from the surfaces of the plasma treated polymers. The characteristic time of the surface charge leakage coincides with the time scale of the decay of the electret response of plasma treated polymer films.