Tree root-inspired robust superhydrophobic coatings with high permeation for porous structures

Superhydrophobic coatings have tremendous potential for protecting porous structures from corrosion. However, the weak adhesion and poor abrasion resistance have long been challenges for their real-life applications. Inspired by tree roots, we prepared a robust superhydrophobic coating by spraying fluorinated nanodiamonds (FNDs) on a permeable epoxy coating. The epoxy can not only coat the surface but also permeate deeply inside a porous substrate and consolidate in situ as tree roots in soil. Thus, the structure is thoroughly reinforced where the pull-off strength reaches 9.4 MPa for concrete. On the other hand, the surface is covered with immobilized FNDs, forming a superhydrophobic surface. Thanks to the ultra-hard FNDs, the coating surface has high abrasion resistance and its superhydrophobicity holds even after 100 abrasion cycles. Moreover, it exhibits self-cleaning, anti-icing, and anticorrosion performance. It is promising in protecting various porous structures such as concrete, wood, and untreated corroded steel.

Superhydrophobic Al2O3–Polymer Composite Coating for Self-Cleaning Applications

Superhydrophobic coatings have a huge impact in various applications due to their extreme water-repellent properties. The main novelty of the current research work lies in the development of cheap, stable, superhydrophobic and self-cleaning coatings with extreme water-repellency. In this work, a composite of hydrothermally synthesized alumina (Al2O3), polymethylhydrosiloxane (PMHS) and polystyrene (PS) was deposited on a glass surface by a dip-coating technique. The Al2O3 nanoparticles form a rough structure, and low-surface-energy PHMS enhances the water-repellent properties. The composite coating revealed a water contact angle (WCA) of 171 ± 2° and a sliding angle (SA) of 3°. In the chemical analysis, Al2p, Si2p, O1s, and C1s elements were detected in the XPS survey. The prepared coating showed a self-cleaning property through the rolling action of water drops. Such a type of coating could have various industrial applications in the future.

Surface Characteristics of Silicon Nanowires/Nanowalls Subjected to Octadecyltrichlorosilane Deposition and n-octadecane Coating

In this study, nanowires/nanowalls were generated on a silicon wafer through a chemical etching method. Octadecyltrichlorosilane (OTS) was deposited onto the nanowire/nanowall surfaces to alter their hydrophobicity. The hydrophobic characteristics of the surfaces were further modified via a 1.5-μm-thick layer of n-octadecane coating on the OTS-deposited surface. The hydrophobic characteristics of the resulting surfaces were assessed using the sessile water droplet method. Scratch and ultraviolet (UV)-visible reflectivity tests were conducted to measure the friction coefficient and reflectivity of the surfaces. The nanowires formed were normal to the surface and uniformly extended 10.5 μm to the wafer surface. The OTS coating enhanced the hydrophobic state of the surface, and the water contact angle increased from 27° to 165°. The n-octadecane coating formed on the OTS-deposited nanowires/nanowalls altered the hydrophobic state of the surface. This study provides the first demonstration that the surface wetting characteristics change from hydrophobic to hydrophilic after melting of the n-octadecane coating. In addition, this change is reversible; i.e., the hydrophilic surface becomes hydrophobic after the n-octadecane coating solidifies at the surface, and the process again occurs in the opposite direction after the n-octadecane coating melts.

Optimization of the surface properties of nanostructured Ni–W alloys on steel by a mixed silane layer

Optimization of the surface properties of nanostructured Ni–W coatings on steel by a mixed silane layer.

Tunable wettability of hierarchical structured coatings derived from one-step synthesized raspberry-like poly(styrene-acrylic acid) particles

Hierarchical structured coatings were fabricated by the assembly of raspberry-like P(S-AA) particles and their wettability could be tuned from hydrophilic to superhydrophobic.

Superhydrophobic surfaces developed by mimicking hierarchical surface morphology of lotus leaf

The lotus plant is recognized as a ‘King plant’ among all the natural water repellent plants due to its excellent non-wettability. The superhydrophobic surfaces exhibiting the famous ‘Lotus Effect’, along with extremely high water contact angle (>150°) and low sliding angle (<10°), have been broadly investigated and extensively applied on variety of substrates for potential self-cleaning and anti-corrosive applications. Since 1997, especially after the exploration of the surface micro/nanostructure and chemical composition of the lotus leaves by the two German botanists Barthlott and Neinhuis, many kinds of superhydrophobic surfaces mimicking the lotus leaf-like structure have been widely reported in the literature. This review article briefly describes the different wetting properties of the natural superhydrophobic lotus leaves and also provides a comprehensive state-of-the-art discussion on the extensive research carried out in the field of artificial superhydrophobic surfaces which are developed by mimicking the lotus leaf-like dual scale micro/nanostructure. This review article could be beneficial for both novice researchers in this area as well as the scientists who are currently working on non-wettable, superhydrophobic surfaces.

Electrospun hybrid fibers with substantial filler contents formed through kinetically arrested phase separation in liquid jet

This study reports polyhedral oligomeric silsesquioxane (POSS)-based hybrid fibers of architectural hierarchy and compositional heterogeneity.