Surface properties of networks containing fluorinated acrylic monomers

The surface properties of acrylic films, obtained through UV curing of bisphenol-A-dihydroxyethyl diacrylate (BHEDA) mixed with fluorinated acrylic monomers, were investigated. Three fluorinated acrylates were selected in order to vary the film composition, namely: 2-(n-perfluorooctylsulphonamido-N-butyl)ethyl acrylate, 2-(n-perfluorooctylsulphonamido-N-ethyl)ethyl acrylate and 2-(n-perfluorooctyl)ethyl acrylate. They were used at concentrations ranging from 0.01 to 1% w/w. The bulk of the films obtained after UV curing was not influenced by the additive as far as the thermal and mechanical properties are concerned. In contrast, the surface properties, examined by measuring the advancing and the receding contact angle with different solvents and evaluating the surface tension, were deeply modified notwithstanding the low concentration of the additive. The change was found to be dependent on the type of monomer and its concentration. Moreover, a clear influence of the substrate in contact with the polymeric film was pointed out. The following substrates were examined: glass, high-density polyethylene and polytetrafluoroethylene; it was shown that the substrate polarity strongly influences the surface properties of the films. X-ray photoelectron spectroscopy analyses allowed the obtaining of the surface composition of the films prepared in the different conditions and could provide a clear interpretation of the previous results