Ultra-thin films based on random copolymers containing perfluoropolyether side chains

Abstract

Random copolymers were synthesised by copolymerizing methylmethacrylate and perfluoropolyetherur-ethanemethacrylate monomers, differing for the structural unit of the fluorinated chain, its end group and its molecular weight. The copolymers obtained had similar molecular weight and polydispersity, with a fluorine content between 5 and 10% wt/wt; they showed remarkable features such as biphasicity with coexistence of soft domains made of the perfluoropolyether chains and hard domains due to the methylmethacrylate backbone: the glass transition temperature T-g of the soft and hard phases was T-g1<90 degrees C and T-g2 congruent to 110 degrees C respectively. All the copolymers were highly hydrophobic: water contact angle was always higher than 105 degrees. The copolymers were used for the preparation of ultra thin films by spin coatings: by atomic force microscopy and X-ray reflectivity the thickness was found in the range of 20-400 angstrom depending on the spinning conditions, in particular the concentration of the spun solutions. The films were also highly smooth, with a roughness lower than 5 angstrom. © 2012, Elsevier Ltd.