Use of plasma polymerized highly hydrophobic hexamethyldissilazane (HMDS) films for sensor development

Hexamethyldissilazane (HMDS) plasma polymerized films can be used in a wide variety of applications due to the facility on plasma polymerization of HMDS molecule and the high resistance to acid or basic corrosion of the formed film. Nonetheless, the hydrophobic character, as well as the possibility of adsorption of organic molecules, did not receive attention yet. In this work HMDS plasma polymerized films, presenting high organic character, were obtained in order to analyze their properties as sensors for organic compounds in N2 and aqueous solutions. lms showed to be not only highly resistant to corrosion in a wide scan of pH, but also presented high water contact angle (approximately 90°). The organic character of the films leads to a high adsorption characteristic for polar and non-polar compounds. The water contact angle measurements vary for 2-propanol aqueous solutions from 90° (0% of 2-propanol) to about 0° (50% of 2-propanol). MDS films were deposited on two different substrates, dielectric and porous silicon (PS), two main issues were found. The films suffered degradation by heating and porous silicon was planarized by the plasma deposition, as shown by infrared spectroscopy, optical and Raman microscopy. tion on piezoelectric quartz crystal (PQC) showed adsorption of polar and non-polar organic compounds carried by N2 and chloroform aqueous solutions. ilms deposited on silicon were electrically characterized showing quickly and reversible response for 2-propanol carried by N2. In saturated environment, the electrical current increases about five times when a range of −5 to 0 V was applied. For n-hexane drops, no reversible electrical characteristics were found. Although some issues were revealed, HMDS highly hydrophobic films showed promising characteristics for sensor development.