[en] In this article, we compare two routes for carrying out in situ nitroxide-mediated polymerization of styrene using the C-phenyl-N-tert-butylnitrone (PBN)/2,2-azobis(isobutyronitrile) (AIBN) pair to identify the best one for an optimal control. One route consists in adding PBN to the radical polymerization of styrene, while the other approach deals with a prereaction between the nitrone and the free radical initiator prior to the addition of the monomer and the polymerization. The combination of ESR and kinetics studies allowed demonstrating that when the polymerization of styrene is initiated by AIBN in the presence of enough PBN at 110 °C, fast decomposition of AIBN is responsible for the accumulation of dead polymer chains at the early stages of the polymerization, in combination with controlled polystyrene chains. On the other hand, PBN acts as a terminating agent at 70 °C with the formation of a polystyrene end-capped by an alkoxyamine, which is not labile at this temperature but that can be reactivated and chain-extended by increasing the temperature. Finally, the radical polymerization of styrene is better controlled when the nitrone/initiator pair is prereacted at 85 °C for 4 h in toluene before styrene is added and polymerized at 110 °C.
Center for Education and Research on Macromolecules (CERM)
Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS ; Fonds pour la formation à la Recherche dans l'Industrie et dans l'Agriculture (Communauté française de Belgique) - FRIA ; Politique Scientifique Fédérale (Belgique) = Belgian Federal Science Policy ; The "CNRS" ; The "Commissariat Général aux Relations Internationales de la Communauté Wallonie-Bruxelles (CGRI), to the Fond National de la Recherche Scientifique (FNRS) (Belgium), and to the Centre National de la Recherche Scientifique (CNRS) (France) for the support of a scientific collaboration program