Shun-Tian Jia

Large-area fabrication of superhydrophobic surfaces for practical applications: an overview

Abstract This review summarizes the key topics in the field of large-area fabrication of superhydrophobic surfaces, concentrating on substrates that have been used in commercial applications. Practical approaches to superhydrophobic surface construction and hydrophobization are discussed. Applications of superhydrophobic surfaces are described and future trends in superhydrophobic surfaces are predicted.

Washable and Wear-Resistant Superhydrophobic Surfaces with Self-Cleaning Property by Chemical Etching of Fibers and Hydrophobization

Superhydrophobic poly(ethylene terephthalate) (PET) textile surfaces with a self-cleaning property were fabricated by treating the microscale fibers with alkali followed by coating with polydimethylsiloxane (PDMS). Scanning electron microscopy analysis showed that alkali treatment etched the PET and resulted in nanoscale pits on the fiber surfaces, making the textiles have hierarchical structures. Coating of PDMS on the etched fibers affected little the roughening structures while lowered the surface energy of the fibers, thus making the textiles show slippery superhydrophobicity with a self-cleaning effect. Wettability tests showed that the superhydrophobic textiles were robust to acid/alkaline etching, UV irradiation, and long-time laundering. Importantly, the textiles maintained superhydrophobicity even when the textiles are ruptured by severe abrasion. Also colorful images could be imparted to the superhydrophobic textiles by a conventional transfer printing without affecting the superhydrophobicity.

Superhydrophobic cotton fabrics prepared by sol-gel coating of TiO2 and surface hydrophobization.

Abstract By coating fibers with titania sol to generate a dual-size surface roughness, followed by hydrophobization with stearic acid, 1H,1H,2H,2H-perfluorodecyltrichlorosilane or their combination, hydrophilic cotton fabrics were made superhydrophobic. The surface wettability and topology of cotton fabrics were studied by contact angle measurement and scanning electron microscopy. The UV-shielding property of the treated fabrics was also characterized by UV-vis spectrophotometry.

Lasting and self-healing superhydrophobic surfaces by coating of polystyrene/SiO2 nanoparticles and polydimethylsiloxane

Maintaining hierarchical roughness and a low surface energy property are keys to long lasting superhydrophobic surfaces. By spraying polystyrene/SiO2 core/shell nanoparticles as a coating skeleton and polydimethylsiloxane as hydrophobic interconnection, lasting and self-healing superhydrophobic surfaces were fabricated. The coating exposed new roughening structures during the rubbing process, thus maintaining a suitable hierarchical roughness, favouring a superhydrophobic property of the surface. Also, the superhydrophobicity of a damaged surface from an air plasma treatment could be automatically restored in 12 h at room temperature or by heat curing and tetrahydrofuran treatment, which helped with the release of hydrophobic polystyrene. This strategy may find practical applications in all kinds of substrates because spray coating is a simple process, and the obtained surfaces possess lasting superhydrophobicity.

Fabrication of Robust and Antifouling Superhydrophobic Surfaces via Surface-Initiated Atom Transfer Radical Polymerization

Superhydrophobic surfaces were fabricated via surface-initiated atom transfer radical polymerization of fluorinated methacrylates on poly(ethylene terephthalate) (PET) fabrics. The hydrophobicity of the PET fabric was systematically tunable by controlling the polymerization time. The obtained superhydrophobic fabrics showed excellent chemical robustness even after exposure to different chemicals, such as acid, base, salt, acetone, and toluene. Importantly, the fabrics maintained superhydrophobicity after 2500 abrasion cycles, 100 laundering cycles, and long time exposure to UV irradiation. Also, the surface of the superhydrophobic fabrics showed excellent antifouling properties.

Preparation of superhydrophobic surfaces on cotton textiles

Abstract Superhydrophobic surfaces were fabricated by the complex coating of silica nanoparticles with functional groups onto cotton textiles to generate a dual-size surface roughness, followed by hydrophobization with stearic acid, 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane or their combination. The wettability and morphology of the as-fabricated surfaces were investigated by contact angle measurement and scanning electron microscopy. Characterizations by transmission electron microscopy, Fourier transformation infrared spectroscopy, and thermal gravimetric analysis were also conducted.

Self-roughened superhydrophobic coatings for continuous oil–water separation

Hydrophobic polydimethylsiloxane based coatings were self-roughened on textiles via a nonsolvent-induced phase-separation method. The self-roughened coatings have superior durability in superhydrophobicity. The obtained superhydrophobic and superoleophilic materials were demonstrated as excellent filters for continuous oil–water separation. The work showed large-scale and practical application for consecutive collection of oil from water.

Fabrication of robust superhydrophobic surfaces by modification of chemically roughened fibers via thiol–ene click chemistry

Superhydrophobic fabrics were fabricated by creation of roughening structures through alkali etching of fibers, modification with mercapto silanes and hydrophobization via thiol–ene click chemistry. Alkali etching resulted in nanoscale pits on the fiber surfaces roughening the fabrics with hierarchical structures, and improved the affinity of fibers for mercapto silanes. The click reaction between dodecafluoroheptyl methacrylate and sulfhydryl fibers lowered the surface energy, making the fabrics superhydrophobic with superoleophilicity. The as-obtained superhydrophobic fabrics showed excellent chemical robustness even after exposure to different chemicals, such as acid, base, salt, acetone, and toluene. Importantly, the fabrics maintained superhydrophobicity after 4500 abrasion cycles, 200 laundering cycles, as well as long time exposure to UV irradiation. The fabrics could be applied in oil/water separation due to their superhydrophobic and superoleophilic properties.

UV-durable superhydrophobic textiles with UV-shielding properties by coating fibers with ZnO/SiO2 core/shell particles

ZnO/SiO(2) core/shell particles were fabricated by successive coating of multilayer polyelectrolytes and then a SiO(2) shell onto ZnO particles. The as-prepared ZnO/SiO(2) core/shell particles were coated on poly(ethylene terephthalate) (PET) textiles, followed by hydrophobization with hexadecyltrimethoxysilane, to fabricate superhydrophobic surfaces with UV-shielding properties. Transmission electron microscopy and ζ potential analysis were employed to evidence the fabrication of ZnO/SiO(2) core/shell particles. Scanning electron microscopy and thermal gravimetric analysis were conducted to investigate the surface morphologies of the textile and the coating of the fibers. Ultraviolet-visible spectrophotometry and contact angle measurement indicated that the incorporation of ZnO onto fibers imparted UV-blocking properties to the textile surface, while the coating of SiO(2) shell on ZnO prohibited the photocatalytic degradation of hexadecyltrimethoxysilane by ZnO, making the as-treated PET textile surface show stable superhydrophobicity with good UV-shielding properties.

Biomimetic superhydrophobic surfaces by combining mussel-inspired adhesion with lotus-inspired coating

Superhydrophobic surfaces on PET textiles were fabricated by combined bioinspiration from the strong adhesion of marine mussels and the two-scale structure of lotus leaves under mild conditions. Dopamine can spontaneously polymerize in alkaline aqueous solution to form a thin adhesive layer of polydopamine (PDA) wrapping on the micro-scale fibers. The as-formed thin PDA layer worked as a reactive template to generate PDA nanoparticles decorated on the fiber surfaces, imparting the textiles with excellent UV-shielding properties as well as a hierarchical structure similar to the morphology of the lotus leaf. After further modification with perfluorodecyl trichlorosilane, the textiles turned superhydrophobic with a water contact angle higher than 150°. Due to the strong adhesion of PDA to a wide range of materials, the present strategy may be extendable to fabrication of superhydrophobic surfaces on a variety of other substrates.