This work examines the functionalization of sugar maple (Acer saccharum) and black spruce (Picea mariana) wood surfaces using an atmospheric‐pressure dielectric barrier discharge in He and He/HMDSO (hexamethyldisiloxane) gas mixtures. Wood samples were placed on one of the electrodes and the plasma was sustained by applying a 3.5 kV peak‐to‐peak voltage at 12 kHz. Analysis of the discharge stability through current–voltage (I–V) characteristics revealed a filamentary behaviour, in sharp contrast with the homogeneous He discharge obtained with a glass sample. Optical emission spectroscopy performed near the wood vicinity revealed strong N2 and ${\rm N}_{{\rm 2}}^{{\rm + }} $ emissions, suggesting that wood outgassing plays an important role in the evolution of the discharge regime. Analysis of the surface wettability through water contact angle (WCA) measurements indicated that freshly sanded wood samples treated in He/HMDSO plasmas became more hydrophobic with WCAs in the 120°–140° range depending on treatment time and wood species. Attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy measurements on samples exposed to He/HMDSO plasmas revealed the deposition of hydrophobic Si(CH3)3‐O‐Si(CH3)2, Si(CH3)3 and Si(CH3)2 functional groups as well as an increase of the CH‐to‐OH band intensity ratio. For relatively thick coatings, the WCA following natural aging under uncontrolled conditions remained constant at 132° ± 3° which highlights the stability of the plasma‐deposited thin films, a very promising result for structural and decorative outdoor applications.

Ultraviolet (UV) light is high-energy radiation that induces degradation of organic compounds, such as wood. To prevent UV damage, several strategies have been used, including creating a UV light barrier at the wood surface. The most common strategy is to apply a coating to the wood surface. However, coating alone may not be effective enough to protect wood exposed outdoors. For example, clear coatings often contain additives to protect the material from UV radiation (hindered amine light stabilizers, quenchers, UV absorbers). This article reports work on the photostability of wood surfaces coated with waterborne nanocomposite urethane-acrylate systems in outdoor conditions. The wood color variation of sugar maple (Acer saccharum Marsh) was measured following accelerated aging. Different types of nanoparticles (ZnO, CuO) were used in water in predispersed and powder forms. Once cured, the nanoparticle dispersions were characterized by transmission electron microscopy. The best photoprotection was obtained with ZnO predispersed in water. Our major conclusion is that ZnO nanoparticles are better than CuO nanoparticles as additives intended to reduce the discoloration of clear-coated wood exposed outdoors. The highest increase in gloss was achieved with the mixture of inorganic and organic UV absorbers, which appear to show synergistic behavior.

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