Deposition of anti‐fog coatings on glass substrates using the jet of an open‐to‐air microwave argon plasma at atmospheric pressure

Abstract

AbstractThis study reports a one‐step process for the formation of anti‐fog coatings on commercial glass substrates using the jet of an open‐to‐air microwave argon plasma at atmospheric pressure with hexamethyldisiloxane (HMDSO) as the precursor for plasma‐enhanced chemical vapor deposition. Optical microscopy and broadband light transmittance measurements revealed significant precursor fragmentation and gas phase association reactions when HMDSO was injected close to the tube outlet, resulting in powder‐like, hydrophobic, and semiopaque glass surfaces. On the contrary, injection of HMDSO close to the substrate led to smoother, homogeneous, hydrophilic, and transparent glass surfaces. In addition, transmittance measurements at 590 nm in humid air according to American Society for Testing and Materials standard tests revealed superior anti‐fogging properties to plasma‐treated glass substrates. On the basis of the optical emission and absorption spectroscopy measurements, electrons, metastable argon atoms, and hot neutral argon atoms were mostly responsible for the significant precursor fragmentation close to the tube outlet, whereas the contribution of hot neutrals and ultraviolet photons became important close to the substrate.