‘Fish-scale’-mimicked stretchable and robust oil-wettability that performs in various practically relevant physically/chemically severe scenarios

Abstract

Stretchable biomimicked special wettability—particularly ‘lotus-leaf’-inspired superhydrophobicity—has emerged as an important avenue for designing various smart and advanced materials. In this context, artificial fish-scale-inspired superoleophobicity—extreme oil-repellency under water—is another important and highly relevant special wettability with regards to its various prospective and relevant applications in practical scenarios. Highly water-compatible hierarchical topographic materials that confer extreme oil-repellency under water are commonly synthesized using polymeric soft hydrogel and brittle metal-oxide coatings that are generally fragile towards both applied tensile stress and chemically harsh aqueous exposures. Thus, designing of stretchable ‘fish-scale’-inspired artificial interfaces is highly challenging, and examples of such stretchable interfaces are rare in the literature. Herein, a highly stretchable (150% strain) and physically/chemically durable underwater superoleophobic interface was developed via simple and strategic integration of covalently cross-linked ‘reactive’ multilayers with a stretchable fibrous substrate. This as-synthesized interface with bio-mimicking wettability remained unaltered under various harsh physical and chemical conditions, including successive (1000 times) tensile deformations, different physical abrasion tests, prolonged exposure (30 days) to UV irradiation, exposures to high and low temperatures (100 °C and 10 °C) and severely complex aqueous phases. Thus, this approach provided a durable and highly stretchable oil-repellent interface that would be useful in various submarine-related and biomedical applications, including prevention of oil contamination, oil/water separations, and anti-bio fouling coating on flexible medically relevant substrates (e.g., catheter balloon). Furthermore, the as-synthesized material was successfully applied to the gravity-driven eco-friendly separation of oil/water mixtures under severe physical/chemical conditions (e.g., extreme conditions of temperatures, tensile strain, pH, sea water, and river water). This study provides a facile and robust strategy for various potential outdoor applications of this biomimicked special wettability.