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

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