Predictive Design, Etch-Free Fabrication of Through-Hole Membrane with Ordered Pores and Hierarchical Layer Structure

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Ultrathin through-hole membranes with spatially ordered and monodisperse nanopores are attracting growing interests in academic studies and industrial applications. Herein, by adapting capillary driven mold-based patterning techniques, the authors present, a facile, benchtop method for the fabrication of such membranes without elaborate post-etching steps and costly instrumentations, which remain the intrinsic fabrication limitations in existing methods. The theory and experiment on the capillary driven imprint depth and timescale are in good agreement, thus providing predictive design guidelines to accurately control lateral (size, shape) and vertical (depth) dimensions of membrane pore features, using a singular master mold template. Another pressing limitation resides in the thin membrane’s difficult detachment from the substrate after patterning. The membrane implementation bottleneck is resolved by a versatile sacrificial layer mediated transfer method that not only facilitates high fidelity transfer of ultrathin membranes onto various target substrates but also enable the assembly of membranes with ideal hierarchical layer structure in which each hierarchy has ordered pore morphology and distinct function. The fabrication approach described herein paves the way for a myriad of greater membrane functions not easily achieved through conventional membranes; especially in filtration, biology, and environmental applications that require exceptional size selectivity and unhindered flow pathways.

By Him Cheng Wong,* Yue Zhang, Virgile Viasnoff,* and Hong Yee Low*