Wetting and adhesion of superhydrophobic surfaces

Background

The wetting of superhydrophobic surfaces has attracted large attention during the last years and today several theories are now available for describing the interplay between surface structure and wetting by water droplets. Most of these theories are base on the Cassie Baxter theory for wetting of rough and heterogeneous surfaces but other approaches based on minimization of the free energy of wetting of the surfaces are also available. Apart from this theoretical development there has also been a dramatic development of techniques for preparation of superhydrophobic surfaces but there is still a lack of environmentally friendly and fast methods for the preparation of durable superhydrophobic surfaces. In the present work the Rapid Expansion Supercritical Carbondioxide (RESS) technique will be used to prepare superhydrophobic surfaces and in the present subproject techniques will be developed for detailed characterization of the surface structure of the prepared surfaces and how this can be related to both the dynamic and static wetting properties of the surfaces. Efforts will also be devoted to evaluate the durability of the surfaces by determining the adhesive behavior of the prepared surfaces.

Objectives

• Methods for structure characterization of superhydrophobic surfaces
• Methods for determining the static and dynamic wetting of superhydrophobic surfaces
• Semiempirical models relating the structure and wetting of the surfaces
• Methods and models for describing the adhesive properties of the prepared surfaces

Activities

• Evaluation of different methods for detailed characterization of the surface structure of the superhydrophobic surfaces
• Identification of equipment needed for determining the static and dynamic wetting of the prepared surfaces. Focus will both on photography and dynamic modulation of the wetted surfaces.
• Development of a theoretical model for describing both the dynamic and static wetting behavior of the superhydrophobic surfaces
• Use of contact mechanical methods for characterizing the adhesive properties of superhydrophobic surfaces.

Time frame of the subproject

This subproject will start in December 2009 and continue as a PhD project for 4.5 years.