Stable superhydrophobic films with a contact angle of 151 +/- 2 degrees were prepared on zinc substrates by a simple immersion technique into a methanol solution of hydrolyzed 1H,1H,2H,2H-perfluorooctyltrichlorosilane [CF3(CF2)5(CH2)2SiCl3, PFTS] for 5 days at room temperature followed by a short annealing at 130 degrees C in air for 1 h. The superhydrophobic film provides an effective corrosion-resistant coating for the zinc interface when immersed in an aqueous solution of sodium chloride (3% NaCl) for up to 29 days. The corrosion process was investigated by following the change of the water contact angle over time and by electrochemical means. The results are compared to those of unprotected zinc interfaces.

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The paper reports on the optical properties of ZnO nanostructures elaborated on a zinc foil substrate by a simple chemical approach. The doping type and density of the ZnO nanostructures were evaluated using electrochemical impedance spectroscopy. XRD diffraction patterns and Raman spectroscopy were used to study the structural properties evolution upon thermal annealing at 300 °C for 1 h in air. Their optical properties, probed by low temperature photoluminescence and room temperature cathodoluminescence (CL), are correlated to their electronic and structural properties. The luminescence of the nanorods is dominated by a broad near band edge emission located in the blue-violet region of the optical spectrum. Analysis of the CL spectra and monochromatic CL images show that the main luminescence has an extrinsic origin, which is tentatively assigned to nitrogen impurities.

A systematic study of the self-diffusion coefficient in hard-sphere fluids, Lennard-Jones fluids, and real compounds over the entire range of gaseous and liquid states is presented. First an equation is proposed for the self-diffusion coefficient in a hard-sphere fluid based on the molecular dynamics simulations of Alder et al. (J. Chem. Phys. 1970, 53, 3813) and Erpenbeck and Wood (Phys. Rev. A 1991, 43, 4254). That expression, extended to the Lennard-Jones fluids through the effective hard-sphere diameter method, represents accurately the self-diffusion coefficients obtained in the literature by molecular dynamics simulations, as well as those determined experimentally for argon, methane, and carbon dioxide. A rough Lennard-Jones expression, which contains besides the diameter σLJ and energy εLJ the translational−rotational factor, A D (which could be correlated with the acentric factor), is adopted to describe the self-diffusion in nonspherical fluids. The energy parameter is estimated using a correlation obtained from viscosity data, and the molecular diameter is obtained from the diffusion data themselves. The equation represents the self-diffusion coefficients with an average absolute deviation of 7.33%, for 26 compounds (1822 data points) over wide ranges of temperature and pressure.

Superhydrophobic surfaces were obtained on copper and galvanized iron substrates by means of a simple solution-immersion process: immersing the clean metal substrates into a methanol solution of hydrolyzed 1H,1H,2H,2H-perfluorooctyltrichlorosilane (CF3(CF2)5(CH2) 2SiCl3, FOTMS) for 3-4 days at room temperature and then heated at 130 degrees C in air for 1 h. Both of the resulting surfaces have a high water contact angle (CA) of larger than 150.0 degrees as well as a small sliding angle (SA) of less than 5 degrees . The formation and structure of the superhydrophobic surfaces were characterized by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectrometry (EDX). SEM images showed that both of the resulting surfaces exhibited special hierarchical structure. The special hierarchical structure along with the low surface energy leads to the high surface superhydrophobicity.

In this paper, on the basis of our recent works on self-diffusion coefficients of Lennard-Jones and real fluids, prediction and correlation models are proposed for the representation of tracer diffusivities of solutes in liquids and supercritical fluids. It has been found that with the parameters obtained from self-diffusion data (the Lennard-Jones energy and diameter) it is possible to predict the tracer coefficients with acceptable accuracy by means of simple combining rules. Moreover, two correlation models involving only one binary parameter (for energy and diameter corrections, respectively) are proposed. Both models exhibit accuracies well inside the experimental uncertainties and give results comparable to the two-parameter Dymond-modified Hildbrand−Batschinski equation.

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Zinc, silicon, and steel superhydrophobic surfaces were prepared by a simple solution-immersion technique. In the case of zinc, the method consists of dipping of the substrate in a prehydrolyzed methanol solution of 1H,1H,2H,2H-(perfluorooctyl)trichlorosilane [CF(3)(CF(2))(5)(CH(2))(2)SiCl(3), PFTS] for 24 h at 50 degrees C. Micron-sized spheres (1.7-2 microm in diameter) were formed on the zinc substrate at 50 degrees C, while a featureless coating was obtained when the solution-immersion process was conducted at room temperature. When the reaction was performed at room temperature, the formation of superhydrophobic coatings took several days (up to 5 days). In contrast, immersion of silicon or steel substrates in the PFTS/methanol solution led to the formation of hydrophobic interfaces even for a prolonged immersion period at 50 degrees C. The formation of superhydrophobic surfaces on silicon and steel surfaces was only possible if a zinc foil was added in the PFTS/methanol solution containing the silicon or steel substrate. X-ray photoelectron spectroscopy analysis was used to characterize the resulting surfaces and to underline a plausible reaction mechanism.