Novel One-Step, in Situ Thermal Polymerization Fabrication of Robust Superhydrophobic Mesh for Efficient Oil/Water Separation

Abstract

In this work, a brand new one-step in situ thermal polymerization (ISTP) preparation of highly stable polymer-coated superhydrophobic materials has been reported. On the basis of the thermal initiation and nonvolatility of an ionic liquid (IL) precursor, robust polymeric layer could be in situ generated and coated to meshes under air atmosphere, while the anchored nanoparticles could provide hierarchical micro/nanostructure. An "oxidative crosslinking" effect was found, and the possible mechanism was proposed. As expected, the obtained mesh exhibited superhydrophobicity with water CA of 158°and superoleophilicity with oil CA of 0°. Besides, the mesh showed self-cleaning effect with a low sliding angle. As for application evaluation, the mesh could act as a filter for the highly efficient separation of a series of oil−water mixtures. More importantly, the mesh exhibited excellent stability and durability toward ultrasonic, abrasion treatment, long-term storage, and even under strongly acidic, alkaline, and saline environment conditions. In summary, this work provided a novel, facile, and scalable method in the fabrication of superhydrophobic surface.

Recent Advances in Robust Superwettable Membranes for Oil–Water Separation

“…Similar to the adhesive‐mediated durable membranes, the use of covalent‐bonding‐based superwettable coatings involving various immobilized hydrogels/aggregates/complexes/particles and building blocks on porous 2D or 3D macroscopic substrates is regarded as a popular strategy for reducing damage arising from abrasion. Recently, several membranes have been developed with improved mechanical (abrasion‐resisting) robustness for the separation of oil–water mixtures . Based on a one‐step alkaline‐induced phase‐inversion process, a robust polyionized sodium polyacrylate‐grafted poly(vinylidene fluoride) (PAAS‐ g ‐PVDF) hydrogel‐coated nonwoven fabric was prepared by Gao et al and used for the separation of immiscible oil–water mixtures.…”

“…After moving forward 965 cm, the WCAs of the resultant surface ranged from 153° to 166°, and the SAs varied between 4° and 7°, indicating superior wearability, despite the 251.2 µm thickness loss (Figure c) . Micro/nanoparticles are the most popular building blocks for superwettable surfaces, and assembled membranes with enhanced mechanical‐abrasion‐resistant properties and performance have been extensively developed …”

“…Second, in addition to measuring the contact angles toward water droplets with a range of pH values and salt concentrations or oil droplets under corresponding aqueous conditions, immersion into corrosive solutions for long periods has often been used to examine the chemical resistance directly, especially before the monitoring of contact angles (Figure b). Despite the fact that superhydrophobic or superomniphobic surfaces are inherently shielded from corrosive aqueous solutions, a loss of superwettability always occurs because of the disappearance of trapped air pockets on immersion.…”

“…Finally, although the abovementioned testing strategies are based on measuring contact angles (Figure a,b) or measuring the change in oil–water (non‐corrosive) separation performance after corrosion (Figure c), which reflect chemical resistance, the practical separation of a variety of complex oil–water mixtures composed of corrosive solutions or organic solvents to imitate real harsh conditions also makes sense (Figure d). Several separation systems especially for corrosive water–oil mixtures, water–organic solvents mixtures, and corrosive water–organic solvents mixtures have been established.…”

Hydrophobic and Anti-Fouling Performance of Surface on Parabolic Morphology

“…In terms of material preparation, in recent years, inspired by surface structures like the lotus leaf self-cleaning surface and mosquito compound eyes [28], a series of superhydrophobic materials were prepared and used for oil-water separation. Some of the most used methods consist of the surface modification of metallic meshes and fabrics, with diverse techniques such as hydrothermal methods [29], leaching [30], electrochemical anodization [31], solution immersion [32,33], and thermal polymerization [34]. Li has done a series of studies on oil-water separation materials in harsh conditions [35], such as fabricating superhydrophobic CS and silica overlap coated meshes for efficient oil-water separation.…”