Functional star-like polystyrenes as organic supports of MeDIP(2,6-iPrPh)(2)FeCl2 catalyst toward ethylene polymerization
Résumé
Star-like polystyrenes composed of a microgel core with functionalized arms have been designed and used as organic supports for a tridentate bis(imino)pyridinyl iron catalyst toward ethylene polymerization. In a first approach, star-like polystyrenes bearing a few number of ethylene oxide units at the periphery of each arm have been prepared to immobilize, through nucleophilic interactions, common aluminum-based activators [methylaluminoxane or trimethylaluminum (TMA)]. A second strategy is based on the synthesis of star-like PS with arms ended either by a benzophenone or a benzoic acid function. Indeed, the reaction of TMA with these functional microgels leads to the in situ formation of alkoxide aluminum-based species at the periphery of the star-like microgels. All these functional PS microgels have been used as supports to immobilize and activate the MeDIP(2,6-iPrPh)(2)FeCl2 catalyst toward ethylene polymerization. High catalytic activities and polyethylene beads of spherical morphology, constituted of polyethylene chains of monomodal molar mass distribution have been obtained, thanks to the organic support.