Synthesis and characterization of a novel difunctional fluorinated acrylic oligomer used for UV-cured coatings

A novel dimethacrylate terminated, poly(2,2,3,4,4,4-hexafluorobutyl acrylate (MATHFA), was synthesized in four-step procedure, and the structures were characterized by FT-IR and 1H NMR spectra. The fluorinated acrylic oligomer was employed as reactive surface additives and copolymerized with bisphenol-A epoxy methacrylate (EMA) in UV-curable formulation to improve the surface properties of UV-cured films. The influence of MATHFA concentration and length, i.e. the number of repeat units on the bulk and surface properties of the films were investigated. Contact angle measurements showed that the high hydrophobic surfaces on the air side of films were obtained by the introduction of fluorinated oligomers in very low amount (less than 1.3 wt.%) in the UV-curable mixed formulation, while the glass side did not changed. The surface composition and the surface enrichment factors measured by X-ray photoelectron spectroscopy (XPS) confirmed the selective enrichment of fluorinated moieties at the outermost surface of cured films and also proved the longer MATHFA was easier to concentrate on the air side than that of shorter MATHFA.