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Deposition of Hydrophobic Functional Groups on Wood Surfaces Using Atmospheric‐Pressure Dielectric Barrier Discharge in Helium‐Hexamethyldisiloxane Gas Mixtures
Author(s) -
Levasseur Olivier,
Stafford Luc,
Gherardi Nicolas,
Naudé Nicolas,
Blanchard Vincent,
Blanchet Pierre,
Riedl Bernard,
Sarkissian Andranik
Publication year - 2012
Publication title -
plasma processes and polymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 74
eISSN - 1612-8869
pISSN - 1612-8850
DOI - 10.1002/ppap.201100222
Subject(s) - hexamethyldisiloxane , contact angle , dielectric barrier discharge , analytical chemistry (journal) , wetting , materials science , surface modification , attenuated total reflection , atmospheric pressure , deposition (geology) , fourier transform infrared spectroscopy , maple , atmospheric pressure plasma , dielectric , composite material , plasma , chemistry , infrared spectroscopy , chemical engineering , chromatography , organic chemistry , optoelectronics , geology , oceanography , engineering , biology , paleontology , quantum mechanics , physics , sediment , botany
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 N 2 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(CH 3 ) 3 ‐O‐Si(CH 3 ) 2 , Si(CH 3 ) 3 and Si(CH 3 ) 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.