Hexamethyldisiloxane-plasma coating of wood surfaces for creating water repellent characteristics

Southern yellow pine wood surfaces were modified under cold plasma conditions in order to create water repellent characteristics. The surface chemistry of the plasma "polymerized" hexamethyldisiloxane (PHMDSO) deposited onto wood surfaces was investigated using Electron Spectroscopy for Chemical Analysis (ESCA) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR). The presence of a crosslinked macromolecular structure, based on Si-O-Si and Si-O-C linkages was detected. Pyrolysis Mass Spectroscopy (MS) was carried out to investigate the nature of the building blocks of the plasma generated macromolecular structure. Plasma modified samples exhibited very high water contact angle values (contact angle = 130 degrees) in comparison to the unmodified samples (contact angle less than or equal to 15 degrees), indicating the presence of a hydrophobic surface. Atomic Force Microscopy (AFM) images, collected both from unmodified and HMDSO-plasma modified samples, indicate the progressive growth of the plasma "polymer", resulting in the deposition of a smooth layer at 10 minutes treatment time. Differential Thermal Analysis (DTA) indicated high thermal stability of the PHMDSO.