Deposition of fluorocarbon groups on wood surfaces using the jet of an atmospheric-pressure dielectric barrier discharge

• Published in: Wood science and technology 2017-11, Vol.51 (6), p.1339-1352
• Main Authors: Levasseur, O., Vlad, M., Profili, J., Gherardi, N., Sarkissian, A., Stafford, L.
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; Ceramics; Composites; Contact angle; Current voltage characteristics; Dielectric barrier discharge; Dimensional stability; Emission spectroscopy; Glass; Hydrophobicity; Life Sciences; Machines; Manufacturing; Natural Materials; Optical emission spectroscopy; Organic chemistry; Original; Photoelectron spectroscopy; Photoelectrons; Plasma; Plasma enhanced chemical vapor deposition; Plasmas (physics); Precursors; Pressure; Processes; Sanding; Spectrum analysis; Voltage; Wood Science & Technology
• ISSN: 0043-7719; 1432-5225
• DOI: 10.1007/s00226-017-0958-x

This work reports the functionalization of sugar maple ( Acer saccharum ) wood surfaces following their exposure to the jet of an atmospheric-pressure dielectric barrier discharge operated in either Ar or N 2 with C 3 F 8 (octafluoropropane) as the growth precursor for plasma-enhanced chemical vapour deposition. Analysis of the current–voltage characteristics (I–V) revealed a filamentary behaviour in all conditions. While more intense current peaks were observed after addition of C 3 F 8 in Ar, a decrease in the discharge current was seen in N 2 /C 3 F 8 plasmas. Optical emission spectroscopy showed the apparition of a CF 2 + continuum and CF 2 rovibrational bands between 225 and 350 nm with increasing applied voltage and precursor concentration in the Ar plasmas; a feature ascribed to the presence of plasma-generated C 3 F 8 fragments. In such conditions, water contact angle (WCA) measurements indicated that freshly sanded wood samples became highly hydrophobic, with WCAs in the 140° range and excellent dimensional stability for a period of up to 125 days. X-ray photoelectron spectroscopy revealed that such behaviours result from the deposition of highly hydrophobic CF x groups on the surface. On the other hand, no increase in surface hydrophobicity was observed following exposure to the jet of N 2 /C 3 F 8 plasmas, probably due to their much lower precursor fragmentation levels.