Physics

Wetting

Nanotechnology

Organic chemistry

Analytical Chemistry (journal)

Surface modification

Engineering

X-ray photoelectron spectroscopy

Nanoparticle

Composite material

Fourier transform infrared spectroscopy

Chemistry

Materials science

Hexamethyldisiloxane

Tetraethyl orthosilicate

Plasma-enhanced chemical vapor deposition

Chemical vapor deposition

Quantum mechanics

Plasma

Chemical engineering

Contact angle

Nanomaterials

Nanoparticles are coated in-flight with a plasma-enhanced chemical vapor deposition (PECVD) process at ambient or elevated temperatures (up to 300 °C). Two silicon precursors, tetraethyl orthosilicate (TEOS) and hexamethyldisiloxane (HMDSO), are used to produce inorganic silica or silica-organic shells on Pt, Au and TiO₂ particles. The morphology of the coated particles is examined with transmission electron microscopy (TEM) and the chemical composition is studied with Fourier-transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). It is found that both the precursor and certain core materials have an influence on the coating composition, while other parameters, such as the precursor concentration, aerosol residence time and temperature, influence the morphology, but hardly the chemical composition. The coated particles are used to demonstrate simple applications, such as the modification of the surface wettability of powders and the improvement or hampering of the photocatalytic activity of titania particles.

Characterization and Applications of Nanoparticles Modified in-Flight with Silica or Silica-Organic Coatings