A Review on Potential Mechanically Resistant Materials for Optical Multifunctional Surfaces: Bioinspired Surfaces with Advanced Properties

Abstract Mimicking naturethrough nanostructuring allows the creation of multifunctional surfaces withremarkable properties, such as anti‐reflectivity, high optical transmittanceand controlled wettability, enabling anti‐icing or anti‐fogging behaviors. These multifunctionalsurfaces have gained significant interest in civil and military domains. However,integrating them into real‐life applications faces challenges related tocost, high‐throughput large‐scale compatible nanofabrication techniques, andtheir mechanical resistance. While sub‐wavelength patterning improves the optical performance,it often comes at the cost of compromising the mechanical resistance. As opticalperformance improves, mechanical resistance tends to deteriorate, and viceversa. To address this challenge, taking inspiration from the lotus leafstructure, where patterns are covered by a thin 2D wax film, covering thepatterns of structured surfaces with a protective layer can be a viablesolution. This protective layer should enhance the mechanical resistance of thesurface without compromising its multifunctional capabilities. This reviewhighlights the most suitable materials that can be employed as protectivecoatings and their potential to enhance the resistance of structured surfaces.The fundamental concept behind the creation of multifunctional optical surfacesis discussed, followed by a comprehensive examination of mechanical tests thatcan be utilized to characterize their mechanical behavior. This review aims topave the way for the development of durable multifunctional optical surfaces,making them more amenable to industrial applications.