Hydrophobic films by atmospheric plasma curing of spun-on liquid precursors

Hydrophobic coatings have been produced on glass and acrylic samples by using a low-temperature atmospheric pressure plasma to polymerize liquid fluoroalkylsilane precursors. The fluoroalkylsilane precursor was dissolved in isooctane and spun onto the substrate at 550 rpm. The sample was then exposed to the reactive species generated from a nitrogen plasma. The plasma was operated with 2.3 vol % N2 in helium at 7.4 W/cm2 at a radio frequency of 27.12 MHz. The total and polar component of the coating's surface energy was found to equal 11.0 and 1.2 dyn/cm, respectively. Average water contact angles of 110 degrees and 106 degrees were measured on the coated glass and acrylic surfaces, respectively. X-ray photoelectron spectroscopy revealed that, after treatment, the fluoroalkyl ligands remained intact on the Si atoms, with a F/C atomic ratio of 2.23.