Superomniphobic, transparent, and antireflection surfaces based on hierarchical nanostructures.

Optical surfaces that can repel both water and oil have much potential for applications in a diverse array of technologies including self-cleaning solar panels, anti-icing windows and windshields for automobiles and aircrafts, low-drag surfaces, and antismudge touch screens. By exploiting a hierarchical geometry made of two-tier nanostructures, primary nanopillars of length scale ∼ 100-200 nm superposed with secondary branching nanostructures made of nanoparticles of length scale ∼ 10-30 nm, we have achieved static contact angles of more than 170° and 160° for water and oil, respectively, while the sliding angles were lower than 4°. At the same time, with respect to the initial flat bare glass, the nanotextured surface presented significantly reduced reflection (<0.5%), increased transmission (93.8% average over the 400 to 700 nm wavelength range), and very low scattering values (about 1% haze). To the authors' knowledge, these are the highest optical performances in conjunction with superomniphobicity reported to date in the literature. The primary nanopillars are monolithically integrated in the glass surface using lithography-free metal dewetting followed by reactive ion etching,1 while the smaller and higher surface area branching structure made of secondary nanoparticles are deposited by the NanoSpray2 combustion chemical vapor deposition (CCVD).

Functionalized Surfaces with Tailored Wettability Determine Influenza A Infectivity.

Surfaces contaminated with pathogenic microorganisms contribute to their transmission and spreading. The development of "active surfaces" that can reduce or eliminate this contamination necessitates a detailed understanding of the molecular mechanisms of interactions between the surfaces and the microorganisms. Few studies have shown that, among the different surface characteristics, the wetting properties play an important role in reducing virus infectivity. Here, we systematically tailored the wetting characteristics of flat and nanostructured glass surfaces by functionalizing them with alkyl- and fluoro-silanes. We studied the effects of these functionalized surfaces on the infectivity of Influenza A viruses using a number of experimental and computational methods including real-time fluorescence microscopy and molecular dynamics simulations. Overall, we show that surfaces that are simultaneously hydrophobic and oleophilic are more efficient in deactivating enveloped viruses. Our results suggest that the deactivation mechanism likely involves disruption of the viral membrane upon its contact with the alkyl chains. Moreover, enhancing these specific wetting characteristics by surface nanostructuring led to an increased deactivation of viruses. These combined features make these substrates highly promising for applications in hospitals and similar infrastructures where antiviral surfaces can be crucial.

Monolithically integrated micro- and nanostructured glass surface with antiglare, antireflection, and superhydrophobic properties.

Hierarchical micro- and nanostructured surfaces have previously been made using a variety of materials and methods, including particle deposition, polymer molding, and the like. These surfaces have attracted a wide variety of interest for applications including reduced specular reflection and superhydrophobic surfaces. To the best of our knowledge, this paper reports the first monolithic, hierarchically structured glass surface that combines micro- and nanoscale surface features to simultaneously generate antiglare (AG), antireflection (AR), and superhydrophobic properties. The AG microstructure mechanically protects the AR nanostructure during wiping and smudging, while the uniform composition of the substrate and the micro- and nanostructured surface enables ion exchange through the surface, so that both the substrate and structured surface can be simultaneously chemically strengthened.

Ultrastable and atomically smooth ultrathin silver films grown on a copper seed layer.

An effective method to deposit atomically smooth ultrathin silver (Ag) films by employing a 1 nm copper (Cu) seed layer is reported. The inclusion of the Cu seed layer leads to the deposition of films with extremely low surface roughness (<0.5 nm), while it also reduces the minimum thickness required to obtain a continuous Ag film (percolation thickness) to 3 nm compared to 6 nm without the seed layer. Moreover, the Cu seed layer alters the growth mechanism of the Ag film by providing energetically favorable nucleation sites for the incoming Ag atoms leading to an improved surface morphology and concomitant lower electrical sheet resistance. Optical measurements together with X-ray diffraction and electrical resistivity measurements confirmed that the Ag film undergoes a layer-by-layer growth mode resulting in a smaller grain size. The Cu seeded Ag growth method provides a feasible way to deposit ultrathin Ag films for nanoscale electronic, plasmonic and photonic applications. In addition, as a result of the improved uniformity, the oxidation of the Ag layer is strongly reduced to negligible values.