Wettability Modification of Nanomaterials by Low-Energy Electron Flux

Controllable modification of surface free energy and related properties (wettability, hygroscopicity, agglomeration, etc.) of powders allows both understanding of fine physical mechanism acting on nanoparticle surfaces and improvement of their key characteristics in a number of nanotechnology applications. In this work, we report on the method we developed for electron-induced surface energy and modification of basic, related properties of powders of quite different physical origins such as diamond and ZnO. The applied technique has afforded gradual tuning of the surface free energy, resulting in a wide range of wettability modulation. In ZnO nanomaterial, the wettability has been strongly modified, while for the diamond particles identical electron treatment leads to a weak variation of the same property. Detailed investigation into electron-modified wettability properties has been performed by the use of capillary rise method using a few probing liquids. Basic thermodynamic approaches have been applied to calculations of components of solid–liquid interaction energy. We show that defect-free, low-energy electron treatment technique strongly varies elementary interface interactions and may be used for the development of new technology in the field of nanomaterials

Compressed Metal Powders that Remain Superhydrophobic After Abrasion

Superhydrophobic “lotus effect” materials are typically not sufficiently robust for most real world applications because their small surface features are both easily damaged and vulnerable to fouling. Here, a method for preparing a new type of superhydrophobic (θ > 162°) composite material by compression of superhydrophobic metal particles is reported. This material, which has no natural analogue, has low-surface-energy microstructures extending throughout its whole volume. Removing its outer layer by abrasion or cutting deep into it does not result in loss of superhydrophobicity because it merely exposes a fresh portion of the underlying superhydrophobic material. The high contact angle is therefore retained even after accidental damage, and vigorous abrasion can be used to restore hydrophobicity after fouling