Research On The Preparation And Properties Of Superamphiphobic Materials Based On Aluminum

Surface wettability is one of the most important properties for solid materials, and an efficient wettability control of solid surface is of great value for both fundamental research and practical application. Since the discovery of the “lotus leaf effect”, materials with super-wettability have drawn much attention. Surfaces with a high water contact angles(CA) particularly larger than 150o are usually called superhydrophobic surface. Louts leaf,a representative example of superhydrophobic surfaces in nature can achieve a water CA of 161o. In recent years, inspired by the various superhydrophobic surfaces on plants or animals, the fabrication of artificial surfaces has made great progress. Biomimetic research indicates that two crucial factors govern the surface wetting behavior. One is the surface roughness represented by various morphological structures, and the other is the surface composition which greatly determines the surface free energy. So, only surfaces with rough morphological structures and low surface free energy can achieve superhydrophobicity. Nowadays, materials with super-wettability have been widely used in many fields, such as self-cleaning, anti-icing/fogging, anti-corrosion, water-collection, drag reduction, oil/water separation, etc. As one of the most important metals, aluminum and its alloys play an irredfplaceable role in daily life. Introducing super-repellency property onto aluminum surface will greatly improve the superficial comprehensive performance, and enlarge the application area. Great progress has been achieved in fabricating superamphiphobic surfaces on aluminum, but some emergent challenges that constrict their widespread, effectively practical applications still exist. One is that most of these reported superamphiphobic surfaces show poor repellency toward low-surface-tension liquids, especially those with a ultralow surface tension less than 25 mN/m(such as dodecane, octane). Another problem is that most of these superamphiphobic surfaces lack of chemical stability and mechanical durability under various severe chemical and physical damages. The poor chemical stability and fragile mechanical durability are still remained urgent issues for the superhydrophobic(superamphiphobic) surfaces. When superhydrophobic(superamphiphobic) surfaces are exposed to some rigorous conditions such as high temperature, a humid environment, hot liquids, strong acid/alkali solutions, oils and solvents contamination etc, the required surface patterns and low-surface-energy layer would be damaged and contaminated, which result in losing super-repellency. Here in this work, we have employed a simple, easy-implemented, and effective approach to fabricate superamphiphobic aluminum surfaces that not only show super-repellency toward octane with very low surface tension, but also have good chemical stability and mechanical durability. The main works are shown as follows:1. Individual nanopore surface and individual microstep surface were fabricated using a simple anodic process and acid etching respectively, and their wettabilities were characterised and compared.2. Superamphiphobic aluminum surfaces with hierarchical micro/nanostructures were successfully achieved by the combination of acid etching and anodic oxidation. We carefully controlled the pore-widening time to tune the morphology structures, and obtained the hierarchical nanowire surface after 16 min’s pore-widening(H-NW-16 surface) which displayed a perfect super-repellency towards various oil droplets. Moreover, H-NW-16 surface can achieve high CA of 151°, and low SA of 12° for octane whose surface tension is only 22 mN/m.3. Various chemical reagents(hot acid/alkali solution, organic solvent, boiling water, etc.) and physical damages(sandpaper abrasion, adhesive tape peeling, blade scratching, etc.) were applied on the as-prepared H-NW-16 surface to test the surface’s stability. It’s proved that the superamphiphobic H-NW-16 surface presented remarkable stability and resistances when exposed to various severely chemical and physical damages. So, the final superamphiphobic surfaces are believed to find very promising and widespread applicability.