Ian Wark Research Institute
ARC Special Research Centre
ARC Special Research Centre
Research Area: Physics, chemistry, chemical engineering, surface engineering
Degree: Honours
Supervisor: A/Prof Rossen Sedev
Description: The contact angle q that a liquid drop forms when placed on a solid substrate reflects the balance between the solid/vapour, solid/liquid and liquid/vapour interfacial tensions. Rough surfaces (e.g. the Lotus leaf, duck feathers, a compact disc surface) are extremely important practically, however, the vast majority of scientific literature describing roughness has either been theoretical or, if experimental, qualitative rather than quantitative in nature. In particular the effect of controlled nanoroughness on both static and dynamic wettability is not understood. We ask the question: at what level does roughness influence contact angle? Can this be designed to control liquid movement or friction?
Chemically homogeneous surfaces can be prepared by coating slides, rods and large particles with thin, smooth, amorphous organic and inorganic coatings. Surface roughness can be altered at the macro level by incorporating various amounts of small particles into special coatings and/or by decorating surfaces with
"craters", droplets and even bubbles.
At the nanoroughness level, self assembled monolayers can be used to create nanosteps of several nm in height. Domains can be formed via photolithography, stamping and Langmuir-Blodgett techniques. The properties and behaviour of these surfaces and their various applications will be investigated using pure liquids, where the molecular size is varied as well as complex fluids where the component concentration and type (eg droplets, polymers or surfactants) can be varied. This project is strongly connected to major European research networks. The project could lead on to doctoral studies.
References
1. M Fabretto, R Sedev and J Ralston, 'Advancing, Receding and Vibrated Contact Angles on Rough Hydrophobic Surfaces', Proceedings of the Third International Symposium on Contact Angle, Wettability and Adhesion, (K.L. Mittal, Ed.) (2002).
2. CI Priest, K Jacobs and J Ralston, 'A Novel Approach to the Formation
of Smooth Gold Surfaces', Langmuir, 18, No. 6, 2438-2440 (2002).
