Hydrophobic-Hydrophilic Character of Hexamethyldisiloxane Films Polymerized by Atmospheric Pressure Plasma Jet

This paper reports on polymerization of hexamethyldisiloxane (HMDSO) using an atmospheric pressure dielectric barrier discharge plasma jet. The aim of the study is to contribute to the knowledge of thin film deposition using a low cost technique of atmospheric pressure plasma. The monomer HMDSO was used as a precursor for polymerization. The discharge was powered using a laboratory made resonant power supply working with sinusoidal voltage signal at a frequency of 8 kHz. The coatings were characterized using Fourier transform infrared spectroscopy, atomic force microscopy, growth rates and surface free energy measurements. The hydrophobic nature of the films was found to be decreased with increasing the plasma power. Fourier transform infrared spectroscopy gave an indication of the dominated inorganic content of the surface at higher discharge. An average growth rate of 220 nm min(-1) was achieved at a monomer flow rate of 5 sccm and discharge power of 12.5 W. The films obtained using plasma jet were found to be stable in aqueous media and well adhered with substrate.