Elaborately aligning bead-shaped nanowire arrays generated by a superhydrophobic micropillar guiding strategy

Abstract

Bead-shaped 1D structures are of great interest due to their unique applications in mesoscopic optics/electronics and their specific ability to collect tiny droplets. Here, a novel method to fabricate aligning bead-shaped nanowire arrays assisted by highly adhesive superhydrophobic surfaces based on a micropillar guiding strategy is presented. Different from previous fabrication techniques, bead-shaped nanowires generated in this method are strictly oriented in a large scale. Rayleigh instability, which occurs at ultralow polymer concentration, can introduce bead-shaped nanowires at the cost of structural strength. Thus, PS spheres are more suitable to serve as bead building blocks to generate firm bead-shaped nanowire arrays. The bead number is tunable by tailoring the polystyrene-sphere/polyvinyl-formal ratio. Furthermore, as-prepared bead-shaped nanowires have the unique ability to directionally drive tiny drops and collect coalesced microdroplets when placed in mist. With an increase in humidity, the nanowires show a segmented swelling behavior in the "bead" parts whereas the "joint nanowire" parts remain the same. Because such bead-shaped nanowires are formed regularly, collected microdroplets upon the beads would not interact with each other. The findings offer new insight into the alignment of bead-shaped nanostructures and might provide promising opportunities in fundamental research and for industrial applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.