Nanostructuring of surfaces using anodic alumina masks - methods, materials and properties
T. Sawitowski, F. Schulz, N. Beyer
AlCove Surfaces GmbH, DE
Keywords: surfaces, nanostructuring, nanopores, alumina
Since the discovery that cleanability is not necessarily linked to smoothness or gloss of surfaces it is interesting to take a closer look at methods allowing surfaces to be structured on a micrometer and nanometer scale. This discovery is based on the observation that plant leaves for example from the sacrificed lotus or insect wings are structured and thus exhibit an improved cleanability. Other bio-surfaces like the eyes of moths are structured as well. Those surfaces show a reduced light reflection. In all cases those surfaces are interfaces with a desired surface structure allowing the improvement of the surface properties. To achieve those improvements methods to nanostructure surfaces in the sub-500 nm range a needed. Beside very sophisticated lithographic methods the use of nanoporous alumina as a mask to structure surfaces is an easy and feasible way to create those structures on very different surfaces. The unique pore structure of anodic alumina represents an ideal and cheap master to be used. Figure 1 gives an example of a masks with 80 nm pore size. Via imprinting or injection moulding nanopillars on top of very different materials like polymers, metals or sol-gel-coatings can be created. Figure 2 shows an example of a structured PMMA surface with pillars in the size of 50 nm diameter and 100 nm height and in figure 3 a surface with 200 nm feature size in aluminium is given.
These masks either used as imprinting stamps or as masks in injection moulding give rise for a fast and easy method for sub-500 nm structuring.
NSTI Nanotech 2003 Conference Technical Program Abstract