Pulsed Plasma Polymerization of Perfluorooctyl Ethylene for Transparent Hydrophobic Thin Coatings

Herein we report on the deposition of transparent hydrophobic thin coatings by radio frequency plasma polymerization(PP) of perfluorooctyl ethylene(PFOE) in both pulsed and continuous wave(CW) modes.The chemical compositions of the resulting PP-PFOE coatings were confirmed by means of Fourier transform infrared spectroscopy(FT-IR) and X-ray photoelectron spectroscopy(XPS).The thicknesses and surface morphologies of the coatings were examined using surface plasmon resonance spectroscopy and atomic force microscopy.The surface wetting properties and optical transmittance were measured using a water contact angle goniometer and UV-vis spectroscopy.The FT-IR and XPS data showed that the PP-PFOE coatings deposited in the pulsed mode had a higher retention of CFgroups compared to those from the CW mode.While the water contact angle of the freshly deposited PP-PFOE from the pulsed mode showed a decrease from 120 degrees to 111 degrees in the first two days,it then remained almost unchanged up to 45 days.The UV-vis data indicated that a PP-PFOE coating 30.6 nm thick had a light transmittance above 90%in the UV and visible ranges.The deposition rates under various plasma conditions are also discussed.