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The styrene polymerization initiated by benzoyl peroxide (BPO) in the presence of N-tert-butyl-á-isopropylnitrone as nitroxide precursor is well-controlled provided that a pre reaction between the nitrone and BPO is carried out in suitable conditions prior to polymerization at a higher temperature. Electron Spin Resonance (ESR) spectroscopy was implemented to probe the nitroxides formed during both steps; i.e. the pre-reaction and polymerization, and to get crucial information regarding the structure of the nitroxides responsible for the polymerization control. ESR studies combined with first principles calculations have evidenced that nitroxides observed during the pre-reaction in the presence of styrene and during the polymerization steps consist of a mixture of two macronitroxides. One is formed by the addition of a growing polystyrene chain to the nitrone as would be expected. However, the second one results from the addition of a polystyrene chain to tert-butyl nitroso that is in-situ formed presumably by decomposition of the first macronitroxide type. Fil: Detrembleur, Christophe. University of Liege, Center for Education and Research on Macromolecules; Bélgica; Fil: Clément, Jean-Louis. Universités d'Aix-Marseille, Laboratoire Chimie Provence; Francia; Fil: Sciannaméa, Valérie. University of Liege, Center for Education and Research on Macromolecules; Bélgica; Fil: Jérôme, Christine. Institut Charles Sadron; Francia; Fil: Catala, Jean-Marie. Institut Charles Sadron; Francia; Fil: Gigmes, Didier. Universités d'Aix-Marseille, Laboratoire Chimie Provence; Francia; Fil: Autissier, Laurent. Universités d'Aix-Marseille, Laboratoire Chimie Provence; Francia; Fil: Botek, Edith. University of Namur, Laboratoire de Chimie Théorique; Bélgica; Fil: Zarycz, Maria Natalia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Centro de Ecologia Aplicada del Litoral (i); Argentina; University of Namur, Laboratoire de Chimie Théorique; Bélgica; Fil: Champagne, Benoît. University of Namur, Laboratoire de Chimie Théorique; Bélgica |
