Engineering a robust, multifunctional superhydrophobic/oleophobic microporous aluminum surface via a two-step chemical etching process

Abstract

Surfaces with unique wettability properties are gaining attention for their widespread applications. Particularly, superhydrophobic surfaces, known for their remarkable water-repellent properties and low adhesion, have gained substantial interest in recent years owing to their versatile applications. Despite their versatile applications, the durability of such surfaces faces challenges like mechanical abrasion, chemical deterioration, and environmental factors, limiting their effectiveness in real-world scenarios. In this study, we successfully fabricated a mechanically robust, cost-effective, and easy-to-process superhydrophobic surface on an aluminum substrate using a two-step chemical etching process. Initially, the hierarchical microporous (HMP) structure was created through chemical etching, followed by the deposition of a self-assembled layer of PFOTS onto the fabricated aluminum substrate, attaining superhydrophobic and oleophobic properties. The surface exhibits remarkable superhydrophobicity with a water contact angle of 162°, while coupled with oleophobic characteristics against a wide spectrum of oils with surface tensions ranging from 21.5–63.3 mN m − 1. We conducted comprehensive characterizations of surface morphology and chemical composition, while also investigating the impact of surface morphology on wettability, physicochemical stability, and antibacterial properties. Mechanical testing revealed that the surface maintained its superhydrophobicity even after undergoing linear abrasion for a distance of 120 cm under an applied pressure of 12.25 kPa. Furthermore, the surface displayed self-cleaning, and anti-fouling, along with significant antibacterial properties against Staphylococcus aureus bacteria, creating a 23 mm zone of inhibition. We believe the proposed method will inspire the fabrication of large-scale superhydrophobic metallic surfaces endowed with multifunctional properties, making them highly suitable for a wide range of industrial applications.