A substrate-friendly, sepiolite-based porous surface infused with slippery liquid with outstanding liquid repellency and metal corrosion resistance

Abstract

Slippery liquid-infused porous surfaces (SLIPSs) have considerable potential in metal corrosion prevention due to their excellent water repellency. The complex fabrication process, poor mechanical stability, and being limited by specific substrates restrict the large-scale development of SLIPS. Here, a pre-oil-infused superhydrophobic coating (SC) for SLIPS was created through careful planning of chemical interactions and micro-nano structures. It is mechanically strong and easy to prepare. Sepiolite with a natural porous structure was chosen as the raw material, bypassing the laborious pore-making process used in traditional SLIPS manufacture. Then, by infusing silicone oil into robust SC, a sturdy SLIPS was successfully created, which allowed a variety of droplets to slide smoothly at low sliding angles (3° ~ 6°) without leaving traces, exhibiting outstanding liquid repellency to some complex droplets and organic liquids. Due to the replacement of air pockets in superhydrophobic coating by silicone oil, the corrosion current density of SLIPS (2.431 × 10−7 A·cm−2) is nearly 2 orders of magnitude and 3 orders of magnitude lower than that of SC and bare Mg substrates, respectively. Thus, SLIPS indicated excellent anti-corrosion ability and longer-term stability than SC after exposure to 3.5 wt% NaCl solution. This substrate-friendly coating without damaging the substrate can be used to protect a wide variety of metallic materials, independent of specific substrates. This facile method provides guidance for the large-scale fabrication of robust smooth surfaces for expanded applications.