Water-based peeling of thin hydrophobic films

TL;DR

This paper demonstrates that slow water dipping can peel off hydrophobic thin films from surfaces via capillary forces, enabling effective removal and transfer of such coatings.

Contribution

It introduces a novel capillary peeling method that uses slow water immersion to remove and transfer hydrophobic thin films from substrates.

Findings

Capillary peeling is more effective at lower dipping velocities.

Lower viscosity water enhances peeling efficiency.

The process allows flawless transfer of films onto the water surface.

Abstract

Inks of permanent markers and water-proof cosmetics create elastic thin films upon application on a surface. Such adhesive materials are deliberately designed to exhibit water-repellent behavior. Therefore, patterns made up of these inks become resistant to moisture and cannot be cleaned by water after drying. However, we show that sufficiently slow dipping of such elastic films, which are adhered to a substrate, into a bath of pure water allows complete removal of the hydrophobic coatings. Upon dipping, the air-water interface in the bath forms a contact line on the substrate, which exerts a capillary-induced peeling force at the edge of the hydrophobic thin film. We highlight that this capillary peeling process is more effective at lower velocities of the air-liquid interface and lower viscosities. Capillary peeling not only removes such thin films from the substrate but also transfers them flawlessly onto the air-water interface.