Reinforcing the Hydrophobicity of Polymeric Surfaces from Fluorinated Star Polymers and Nanogels

Nanogels and starlike arm-first polymer based on 1H.1H.2H.2H-perfluorodecylacrylate were designed by controlled radical cross-linking copolymerization in solution, using ethyl 2-[(phenylcarbonothioyl)sulfanyl]propanoate as a reversible chain transfer agent. Investigations into (lie structure of these fluorinated branched polymers by means of atomic force microscopy (AFM), differential scanning calorimetry, and polarized Optical microscopy revealed it crystalline organization which decreased its the cross-link density increased. Films were prepared from these branched architectures by coating on various substrates. Their properties were studied in comparison with films prepared from linear homologues. Contact angle measurements showed similar hydrophobicity after coating. However a significant decrease of hydrophobicity was observed after annealing in the case of films prepared from linear Polymers, whereas it was almost preserved for films corresponding to branched architectures. For films of same thickness, this observation was due to an important dewetting of the substrate in the case of linear polymers whereas this phenomenon was inhibited in the case of branched architectures, as revealed by optical micro copy and AFM analyses.