Quantification and Physics of Cold Plasma Treatment of Organic Liquid Surfaces

TL;DR

This paper investigates how cold plasma treatment alters the surface energy of silicone oils and castor oil, introducing two methods for quantification based on contact angle measurements and electret response analysis.

Contribution

It presents two independent methods to quantify plasma-induced surface energy changes in organic liquids, linking contact angles and electret responses to surface modifications.

Findings

Plasma treatment increases oil/air surface energy.

Derived an expression relating contact angle to surface energy.

Measured electret response to assess plasma effects.

Abstract

Plasma treatment increases the surface energy of condensed phases: solids and liquids. Two independent methods of the quantification of the influence imposed by a cold radiofrequency air plasma treatment on the surface properties of silicone oils (polydimethylsiloxane) of various molecular masses and castor oil are introduced. Under the first method the water droplet coated by oils was exposed to the cold air radiofrequency plasma, resulting in an increase of oil/air surface energy. An expression relating the oil/air surface energy to the apparent contact angle of the water droplet coated with oil was derived. The apparent contact angle was established experimentally. Calculation of the oil/air surface energy and spreading parameter was carried out for the various plasma-treated silicone and castor oils. The second method is based on the measurement of the electret response of the plasma-treated liquids.