Wetting behavior of polymer coated nanoporous anodic alumina films: transition from super-hydrophilicity to super-hydrophobicity.

We show that nanoporous anodic alumina films, with pore diameters in the range 10-80 nm, can be transformed from being very hydrophilic (or super-hydrophilic) to very hydrophobic (or super-hydrophobic) by coating the surface with a thin (2-3 nm) layer of a hydrophobic polymer. This dramatic transformation happens as a result of the interplay between surface morphology and surface chemistry. The coated surfaces exhibit 'sticky' hydrophobicity as a result of ingress of water into the pores by capillary action.