Development of polyurethane-based superhydrophobic coatings on steel surfaces.

In this study, a superhydrophobic coating on steel surface has been developed with polyurethane, SiO2 nanoparticles and hexadecyltrimethoxysilane by using a spin-coating technique. Characterization of the coated steel surface was done by using the contact angle measurement technique, scanning electron microscopy and Fourier transform infrared spectroscopy. With a water tilt angle of 4° ± 2° and static contact angle of 165° ± 5°, the coated surface shows a superhydrophobic and self-cleaning nature. Chemical, thermal, mechanical stability tests and droplet dynamic studies were done to evaluate performance of the coating. Excellent self-cleaning, anti-fogging and anti-corrosion properties of coated steel surfaces make them ideal for industrial applications. This article is part of the theme issue 'Bioinspired materials and surfaces for green science and technology (part 3)'.

Facile approach to develop anti-corrosive superhydrophobic aluminium with high mechanical, chemical and thermal durability.

Durable, superhydrophobic and self-cleaning aluminium surfaces with high corrosion resistance are desirable in many industrial applications. In this study, a facile approach is used to produce aluminium surfaces with superhydrophobicity with a low tilt angle by creating desired roughness structure by immersing in NaOH solution followed by lowering the surface energy by immersing in hexadecyltrimethoxysilane solution. The coated samples show water contact angle of 164 ± 7° and tilt angle of 5 ± 1°. Droplet dynamics of the coated surfaces was investigated. Surfaces exhibited self-cleaning properties. In addition, mechanical, chemical and thermal stability tests were performed. Electrochemical tests of coated surfaces demonstrated anti-corrosion properties with low corrosion current density and high corrosion potential. This article is part of the theme issue 'Bioinspired materials and surfaces for green science and technology'.

Surface Modification of Cotton Fabric Using TiO2 Nanoparticles for Self-Cleaning, Oil-Water Separation, Antistain, Anti-Water Absorption, and Antibacterial Properties.

Superhydrophobicity is of interest for practical applications such as water repellency, self-cleaning, stain resistance, antibacterial properties, and oil-water separation. In this work, a superhydrophobic coating on cotton fabric is prepared by simple immersion in TiO2 nanoparticles and perfluorodecyltriethoxysilane solution. Its antiwetting properties, surface morphology, and functionality are characterized. The cotton fabric shows superhydrophobicity with a water static contact angle of 169.3 ± 2.1° and tilt angle of 6.3 ± 2.0°. The coating is also characterized by performing stability tests, and it shows excellent mechanical durability, chemical stability, and thermal stability. Additionally, the water droplet dynamic on the coated surface is also studied. The coated cotton fabric exhibits excellent self-cleaning, stain resistance, rust stain resistance, anti-water absorption, and antibacterial properties. It can also be used in oil-water separation with a high separation efficiency and excellent reusability.

Freshwater production via efficient oil-water separation and solar-assisted water evaporation using black titanium oxide nanoparticles.

Fabrication of a multipurpose superhydrophobic mesh via modification of a galvanized steel mess using black titanium oxide nanoparticles and perfluorodecyltriethoxysilane is reported. Modified mesh exhibits superhydrophobicity with a water static contact angle of 157° ± 2 along with a tilt angle of 5° ± 1 and suitable chemical, thermal, mechanical stability, and self-cleaning ability. The droplet dynamic behavior of superhydrophobic mesh revels the impact velocity is 1.5 ms-1 for splashing of the water droplet. The developed mesh is studied for freshwater generation from oily water and seawater via efficient oil-water separation and solar evaporation, respectively. A proficiency of 99% and 88% is achieved for oil-water separation from mixture and emulsion, respectively. Solar evaporation efficiency of 64% and 76% are recorded under low-intensity light (225 Wm-2) and natural sunlight (591 Wm-2), respectively, from distilled water. For seawater, the evaporation efficiency of 69% is achieved under natural sunlight. Present approach can be applied to any size and shape of the mesh and has great industrial applications.