Biomimetic polymeric superhydrophobic surfaces and nanostructures: from fabrication to applications

Abstract

Numerous research studies have contributed to the development of mature superhydrophobic systems. The fabrication and applications of polymeric superhydrophobic surfaces have been discussed and these have attracted tremendous attention over the past few years due to their excellent properties. In general, roughness and chemical composition, the two most crucial factors with respect to surface wetting, provide the basic criteria for yielding polymeric superhydrophobic materials. Furthermore, with their unique properties and flexible configurations, polymers have been one of the most efficient materials for fabricating superhydrophobic materials. This review aims to summarize the most recent progress in polymeric superhydrophobic surfaces. Significantly, the fundamental theories for designing these materials will be presented, and the original methods will be introduced, followed by a summary of multifunctional superhydrophobic polymers and their applications. The principles of these methods can be divided into two categories: the first involves adding nanoparticles to a low surface energy polymer, and the other involves combining a low surface energy material with a textured surface, followed by chemical modification. Notably, surface-initiated radical polymerization is a versatile method for a variety of vinyl monomers, resulting in controlled molecular weights and low polydispersities. The surfaces produced by these methods not only possess superhydrophobicity but also have many applications, such as self-cleaning, self-healing, anti-icing, anti-bioadhesion, oil-water separation, and even superamphiphobic surfaces. Interestingly, the combination of responsive materials and roughness enhances the responsiveness, which allows the achievement of intelligent transformation between superhydrophobicity and superhydrophilicity. Nevertheless, surfaces with poor physical and chemical properties are generally unable to withstand the severe conditions of the outside world; thus, it is necessary to optimize the performances of such materials to yield durable superhydrophobic surfaces. To sum up, some challenges and perspectives regarding the future research and development of polymeric superhydrophobic surfaces are presented.

Micro‐/Nanostructured Interface for Liquid Manipulation and Its Applications

“…Cassie–Baxter Model : The Wenzel model has a weakness that it is only suitable for the homogenous surface . Therefore, Cassie–Baxter model was developled .…”

“…Two important factors including micro‐/nanoscale hierarchical structures and materials with suitable surface energy are co‐related to the construction of superhydrophobic surface. There are two approaches to construct superhydrophobic surface, the first one is combining multiple‐scale roughness with inherently hydrophobic coatings, and the second one is the combining of re‐entrant geometry with hydrophilic surfaces . For example, Zhang et al fabricated CuO nanoneedle‐covered copper surfaces by anodization and then chemical modification with fluoroalkyl‐silane (FAS‐17) ( Figure a).…”

Reversible switch between underwater superaerophilicity and superaerophobicity on the superhydrophobic nanowire-haired mesh for controlling underwater bubble wettability

“…Therefore, the water droplet on the mesh is at the Cassie wetting state. 22,23,26 As shown in Figure 4a, the droplet is just in contact with the top peaks of the nanowires of the rough mesh, without wetting the surface microstructures. The air filled in the surface microstructure forms a trapped air cushion underneath this water droplet.…”

Facile Preparation of Hydrophobic Aluminum Oxide Film via Sol-Gel Method

“…It may be attributed to the upper nanowires and lower nanohole structures like some hills shown in SEM images of AOFs (Figure 1J). The hills, holding water on the surface, play the vital role in hydrophobic properties comparable to lotus effect (Samaha et al, 2012; Wen et al, 2017). …”