Studies of drag on the nanocomposite superhydrophobic surfaces

Abstract

Highlights• The nanocomposite thin films of stearic acid (SA)-functionalized ZnO nanoparticles incorporated in epoxy polymer matrix have been achieved.• SA-functionalization of ZnO nanoparticles in the thin films was confirmed by XRD and FTIR.• The measured rms roughness of the thin film is found to be 12 ± 1 µm with the adhesion of 5B on glass.• The wetting property shows that the surface of the film is superhydrophobic with the CA of 156 ± 4° and CAH of 4 ± 2°.• The drag reduction on the surface of superhydrophobic glass sphere is 16% lower than as-received glass sphere. AbstractThe nanocomposite thin films of stearic acid (SA)-functionalized ZnO nanoparticles incorporated in epoxy polymer matrix have been achieved. The X-ray diffraction (XRD) studies show the formation of zinc stearate on ZnO nanoparticles as the confirmation of SA-functionalization of ZnO nanoparticles in the thin films. Morphological analyses reveal the presence of micro-holes with the presence of irregular nanoparticles. The measured root mean square (rms) roughness of the thin film is found to be 12 ± 1 µm with the adhesion of 5B on both glass and aluminum substrates. The wetting property shows that the surface of the film is superhydrophobic with the contact angle of water of 156 ± 4° having contact angle hysteresis (CAH) of 4 ± 2°. The average terminal velocity in the water of the as-received glass spheres and superhydrophobic spheres were found to be 0.66 ± 0.01 m/s and 0.72 ± 0.01 m/s respectively. Consequently, the calculated average coefficients of the surface drag of the as-received glass sphere and superhydrophobic glass sphere were 2.30 ± 0.01 and 1.93 ± 0.03, respectively. Hence, the drag reduction on the surface of superhydrophobic glass sphere is found to be approximately 16% lower than as-received glass sphere.Graphical abstract

A Multi-Method Approach for Quantification of Surface Coatings on Commercial Zinc Oxide Nanomaterials

“…A modified extraction procedure using pyridine-d 4 in methanol-d 4 gave a higher recovery of stearic acid from ZnO NPs (43 µmol/g), although this value was still lower than the estimate from TGA (see below) [28]. This may be caused by the proposed strong chemical interaction between ZnO and stearic acid, since some literature reports indicate that stearic acid is covalently bonded to ZnO [29]. Therefore, we investigated a two-phase method in which stearic acid modified ZnO was first dispersed in an organic solvent (toluene, cyclohexane, and chloroform tested) and then combined with HCl (0.4 M) followed by 24 h reflux.…”

Potentiodynamic study of Al–Mg alloy with superhydrophobic coating in photobiologically active/not active natural seawater

“…If a superhydrophobic surface is A c c e p t e d M a n u s c r i p t immersed, a plastron of air is trapped, thereby avoiding water penetration and, hence, wetting [2]. Superhydrophobic surfaces for seawater applications have been investigated in order to control corrosion [3,4], biofouling growth, [5,6], and friction drag [7,8]. Thinking about navigation and hulls, the simultaneous coexistence of these properties in a unique solution sounds extremely attractive.…”

Effect of Various Surface Coatings on De-Icing/Anti-Icing Fluids Aerodynamic and Endurance Time Performances

“…The coatings were selected primarily for their facility of application, using a spray gun, over medium to large scale substrates. All the coatings are recognized to reduce the ice adhesion due to previous studies conducted at The Anti-icing Materials International Laboratory (AMIL) [3,[10][11][12][13][14].…”