Superwetting Patterned Membranes with an Anisotropy/Isotropy Transition: Towards Signal Expression and Liquid Permeation

Abstract

Superwetting membranes with responsive properties have attracted heightened attention because of their fine-tunable surface wettability. However, their functional diversity is severely limited by the "black-or-white" wettability transition. Herein, we describe a coating strategy to fabricate multifunctional responsive superwetting membranes with SiO2/octadecylamine patterns. The adjustable patterns in the responsive region are the key factor for functional diversity. Specifically, the coated part of the membrane displayed a superhydrophobicity/superhydrophilicity transition at different pH values, whereas the uncoated part exhibited invariant superhydrophilicity. On the basis of this anisotropy/isotropy transition, the membranes can serve as either responsive permeable membranes or signal-expression membranes, thus enabling the responsive separation and permeation of liquids with satisfactory separation efficiency (>99.90 %) and flux (ca. 60 L m(-2) h), as well as real-time liquid signal expression with alterable signals.