Fabrication of length-controlled polymer nanopillars using poly(dimethylsiloxane) filled anodised aluminium oxide templates

Fabrication of nanopillars via anodised aluminium oxide (AAO) serving as a template is cost-effective and widely used. However, control over the length of nanopillars by this method remains a challenge. Presented is a two-step wetting method to fabricate polymer nanopillars of controlled length using a poly(dimethylsiloxane) (PDMS) filled AAO template. Firstly, by filling uncured PDMS into the nanopores of AAO and then dissolving partially, the depth of the nanopores is adjusted and increases with the dissolving time. Subsequently, the second wetting step by polymeric liquid with the PDMS filled AAO template yields length-controlled nanopillars. Nanopillars of different lengths and different polymers are fabricated using this method via both melt capillary infiltration and solution wetting. It is also demonstrated that the PDMS filled AAO templates in the presented method are reusable. This method is simple, cost-effective and may facilitate applications of polymer nanopillars of controlled length.