AUSTRALIA - JAPAN SYMPOSIUM

AUSTRALIA - JAPAN SYMPOSIUM ON EARTH SYSTEMS SCIENCE
AND ON NANOMATERIALS

Canberra, 21 November 2006

Super hydrophobicity through engineering nanoscale surface roughness
Professor Robert Norman Lamb, University of New South Wales

Professor Lamb received his BSc PhD in Chemistry from the University of Melbourne followed by a PhD in Physics from the Cavendish Laboratory, University of Cambridge. He has published 165 papers in surface science and hold 31 patents in the area of thin films and coating for applications in Photonics and Materials. He has a major interest in surfaces as templates for the Nanotechnology revolution.

Creating 'new' and useful properties from combinations of 'old' materials is one of the promises of the 'NANO' revolution.

An example is in this work where the chemical synthesis and physics of novel hybrid organic/inorganic thin films that act as 'non stick' superhydrophobic coatings will be described.

Superhydrophobicity generally refers to surfaces with water contact angle (θ) >150°. Fabrication of superhydrophobic coatings has become a rapidly expanding area of research over the last few years, due primarily to their self-cleaning ability. The two key attributes to be considered in the 'chemical design' of such interfaces are the chemical composition and physical structure. In this work we describe coatings in which the nanostructural roughness is manipulated to create superhydrophobicity from (chemically) low (θ <90°) contact angle materials. These have fabricated surfaces based on relatively common chemical components without the use of fluorinated groups which are usually common in such coatings.

Scanning Electron Microscopy reveals that roughness is generated by homogeneous coverage of the coating over the surface with agglomeration of particulates within the film. The relationship between micro/nanostructure and wettability is of considerable importance.

This demonstration of 'nano' behaviour to dramatically modify the thin film coatings is an example of what is presently described as nanotechnology and represents considerable savings in energy both in environmentally friendly fluorofree processing and natural self cleaning.