Perfluorinated Polymer Monolayers on Porous Silica for Materials with Super Liquid Repellent Properties

Abstract

We report on the preparation of water- and oil-repellent surfaces using surface-attached monolayers of perfluorinated polymer molecules. A covalent attachment of the polymer molecules to the substrate surfaces is achieved by generation of the polymer chains through starting a surface-initiated radical-chain polymerization of a fluorinated monomer. To this, self-assembled monolayers of azo initiators are attached to SiO2 substrates, which are used to kick off the polymerization reaction in situ. The growth of the fluorinated polymer brushes and the characterization of the obtained surfaces by Fourier transform infrared spectroscopy, surface plasmon spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements is described. It is shown that perfluorinated polymer films can be grown with controlled thicknesses on flat and even on porous silica surfaces, essentially without changing the surface roughness. The combination of the low surface energy coating and the surface porosity allows generation of materials which are both water and oil repellent.