RESUMO
We report on a simple and effective way to attach thin polymer films to solid surfaces. The system is based on a thermosensitive sulphonyl azide derivative that is immobilized to SiO(2) surfaces via chlorosilane anchoring group and subsequently covered with a polymer film. Upon heating the sulfonyl azide decomposes, leading to a C-H insertion reaction from the adjacent polymer chain resulting in a covalent attachment of the polymer to the surface. Any nonbound polymer can be removed by extraction. The method allows to attach a wide spectrum of polymers to solid surfaces. The film thickness of the monolayers can be tuned by adjusting the molecular weight of the polymer used and to some extent, the thermolysis conditions. The film thickness increases linearly with the radius of gyration of the polymers used for attachment. We have successfully attached thin layers of poly (styrene), poly (dimethylacryl amide) and poly (heptadecafluorodecylacrylate).
RESUMO
The synthesis of methyl methacrylate (MMA) brush from the surface of magnetite nanoparticles (core-shell structure), from initiator moieties anchored covalently to the nanoparticles, via room temperature atom transfer radical polymerization (ATRP) is described. The surface-initiated polymerization was carried out from a surface-confined initiator containing a 2-bromoisobutyrate moiety with Cu(I)Br/PMDETA catalytic system. The initiator moiety was covalently anchored to the nanoparticles via a two step modification reaction scheme. Controlled polymerization was observed if ethyl-2-bromoisobutyrate (2-EiBrB) was added as a free/sacrificial initiator. A linear increase of molecular weight and a narrow molecular weight distribution of the PMMA formed in solution, provide evidence for a controlled surface-initiated polymerization, leading to surface-attached polymer brushes under mild conditions. The grafted PMMA provides good stability and dispersibility for the nanoparticles in organic solvents.
