Applied Surface Science, Vol.255, No.22, 9000-9005, 2009
Modification of polycarbonate surface properties by nano-, micro-, and hierarchical micro-nanostructuring
Polycarbonate surfaces were patterned with nanopillars, microbumps, or nanopillars superimposed on microbumps. Patterning was achieved by applying nanoporous anodized aluminum oxide (AAO) membranes, microstructured aluminum foil, or anodic alumina on microstructured aluminum as mold inserts in injection molding. The effect of the different-sized structures on properties of the polycarbonate surface was investigated in contact angle measurements with water and oleic acid. The water contact angle increased from 82 degrees on the smooth surface to 139 degrees on the hierarchical micro nanostructure. The transmittance of the polycarbonate increased with nanopatterning, while the reflection properties of the polycarbonate surface decreased. Reflection was lowest for the nanostructure with 53 nm pillar diameter and 77 nm interpillar distance. Values ranged from 0.6 to 1.1% over the whole wavelength range of visible light, which was 4-5% units lower than the corresponding values for the smooth polycarbonate. (C) 2009 Elsevier B. V. All rights reserved.