Electron-Induced Superhydrophobicity of Nanoparticles

Controllable modification of nanoparticles wettability allows both understanding fine physical mechanism acting on their surfaces, and improvement of key properties in a number of nanotechnology applications. The modification of nanoparticles generating superhydrophobic state arouses especially a strong interest, since various physical phenomena, such as such as sticking, agglomeration, friction of nanoparticles are defined by wettability properties. Today the developed technologies mainly apply diverse modification methods changing chemical identity of nanoparticle surfaces by means of intermediate layers of different chemical nature. We developed a new concept based on defect free low energy electron-induced surface energy modification. It has been found that electronirradaited ZnO-nanoparticles strongly change their wettability from superhydrophilic to superhydrophobic state.1,2 Pronounced variation of wettability from high hydrophilic state to superhydrophobic has been observed in ZnO-nanoparticles (the average particle size was 200 nm), irradiated by low energy electrons (300eV). The untreated nanopaticles easily adsorb the deposited water droplets and water, wetting the nanoparticles, penetrates inside ZnO-nanopowder in a short time ~0.2sec (Fig.1). Electron irradiation dramatically changes the water droplet behavior on the ZnO nanopaticle sample surface (Fig.2). The water does not wet the surface and does not