Analysis of transport phenomena during plasma deposition of hydrophobic coatings on porous cellulosic substrates in plane‐to‐plane dielectric barrier discharges at atmospheric pressure

In this study, four‐layer stacks of bleached, unrefined Kraft papers are exposed to a plane‐to‐plane dielectric barrier discharge at atmospheric pressure operated in a glow‐like discharge regime and sustained in a mixture of hexamethyldisiloxane and helium gases. Scanning electron microscopy confirms that the plasma‐deposited coating follows the roughness of the porous cellulosic substrate. Whereas fairly spatially homogeneous coatings are obtained on silicon, significant variations of the coatings' thickness, organic content, and water contact angle are observed along the gas flow lines on the Kraft paper. These effects are even more important in the presence of substrate outgassing. In addition, plasma‐generated species sequentially penetrate down to the fourth layer of the cellulosic substrate, rendering surfaces hydrophobic with very low water absorption kinetics.