Formation of A Stable, Hydrophobic Self-Assembled Monolayer on Mica Via Vapor Deposition

Although much is known about macroscopic surfaces and drops at the millimeter scale, electrowetting at the nanoscopic level is not fully understood. The goal of the project is to create a smooth, stable surface to be employed in electrowetting measurements. Contact angle measurements and Atomic Force Microscopy were employed to study the stability of perfluorinated siloxane films made from the FDTS precursor (CF3(CF2)7(CH)2SiCl3), a self-assembling monolayer, on the surface of mica. Using vapor-phase deposition, we determined the important experimental variables needed to achieve robust hydrophobic films. We investigated the importance of post-reaction annealing on the stability of the film and saw no significant effect. However, a significant increase in the stability of the monolayer coating was observed when successive cycles of reaction and pumping were employed. In addition, the hydrophobic films were found to be more stable when stored in air than in water.