Dual-Functional Superhydrophobic Textiles with Asymmetric Roll-Down/Pinned States for Water Droplet Transportation and Oil–Water Separation

Abstract

Superhydrophobic surfaces with tunable adhesion from lotus-leaf to rose-petal states have generated much attention for their potential applications in self-cleaning, anti-icing, oil-water separation, microdroplet transportation, and microfluidic devices. Herein we report a facile magnetic-field-manipulation strategy to fabricate dual-functional superhydrophobic textiles with asymmetric roll-down/pinned states on the two surfaces of the textile simultaneously. Upon exposure to a static magnetic field, fluoroalkylsilane-modified iron oxide (F-FeO) nanoparticles in polydimethylsiloxane (PDMS) moved along the magnetic field to construct discrepant hierarchical structures and roughnesses on the two sides of the textile. The positive surface (closer to the magnet, or P-surface) showed a water contact angle up to 165°, and the opposite surface (or O-surface) had a water contact angle of 152.5°. The P-surface where water droplets easily slid off with a sliding angle of 7.5° appeared in the "roll-down" state as Cassie mode, while the O-surface was in the "pinned" state as Wenzel mode, where water droplets firmly adhered even at vertical (90°) and inverted (180°) angles. The surface morphology and wetting mode were adjustable by varying the ratios of F-FeO nanoparticles and PDMS. By taking advantage of the asymmetric adhesion behaviors, the as-fabricated superhydrophobic textile was successfully applied in no-loss microdroplet transportation and oil-water separation. Our method is simple and cost-effective. The fabricated textile has the characteristics of superhydrophobicity, magnetic responsiveness, excellent chemical stability, adjustable surface morphology, and controllable adhesion. Our findings conceivably stand out as a new tool to fabricate functional superhydrophobic materials with asymmetric surface properties for various potential applications.

Nonflammable and Magnetic Sponge Decorated with Polydimethylsiloxane Brush for Multitasking and Highly Efficient Oil–Water Separation

“…As displayed in Figure c, the XRD spectrum of PDMS‐Fe 3 O 4 @MF exhibited main diffraction peaks of Fe 3 O 4 NPs at 30.1°, 35.5°, 43.1°, 57.0°, and 62.6°, which strongly demonstrated the codeposition of magnetic Fe 3 O 4 nanofillers. And due to that, both the PDA‐Fe 3 O 4 @MF and PDMS‐Fe 3 O 4 @MF exhibited effective magnetic responsibility.…”

Magnetoresponsive Surfaces for Manipulation of Nonmagnetic Liquids: Design and Applications

“…[84,106,107] For example, Yang et al fabricated a superhydrophobic surface with a dense array of magnetic micropillars for controlling droplet adhesion. Such property can be used to capture and release droplets, enabling transferring droplets from one surface to another.…”

Chemically Resistant, Electric Conductive, and Superhydrophobic Coatings

“…Incorporation of particles in water drop to eventually clean the surface is clearly visible. [41,42] Furthermore, surfaces with different adhesive properties can be used for carrying different reactions in confined volumes. The snapshots from the video are shown in Figure 3b.…”