Multibioinspired Janus membranes with superwettable performance for unidirectional transportation and fog collection

Abstract

Heterogeneous wetting surfaces have played an important impact for droplet manipulation in various aspects, such as fundamental research, domestic and industrial production. Here, inspired by the asymmetric hierarchical structure of cactus spines, the interleaved lyophilic/lyophobic (LI/LO) micropattern of beetle back, slippery liquid-infused porous surface of Nepenthes plants, and directional pumping performance of emergent aquatic plants, we designed a multibioinspired Janus membrane with heterogeneous wetting and interpenetrating structure. The multibioinspired Janus membrane was fabricated by employing combined strategies of spraying and etching, which exhibits a liquid unidirectional manipulation behaviour for highly efficient fog collection. Moreover, Cu(OH)2 nanofibers and ZnO-tetrapod from tip to root with LI wetting, LO wetting, and slippery abilities are constructed by adjusting the deposited site of low-energy silicone oil during the dewetting process. And liquid droplets can be gathered to the micropore bumps from all directions and spontaneously permeate through micropores to LI Cu(OH)2 nanofibers as a reservoir without extra force. As a result, droplet can only transport by capillary force and slippery properties, which generates from the Janus membrane with array bumps and a layer of film infused with lubricant. This Janus membrane with high water collection efficiency and excellent recyclability has the promising candidates for a broad field of applications, including liquid separation, droplets manipulation, and other ranges.