Novel bidentate phosphine modified Pd(acac) 2/BF 3OEt 2 catalyst system for the homopolymerization of alkylnorbornenes and copolymerization with norbornene

Abstract

The Pd(acac) 2 + nPh 2P(CH 2) m PPh 2 + 25BF 3OEt 2, n = 1–3, m = 1–6, catalyst system has been successfully employed for the homopolymerization of 5-alkyl-2-norbornenes and their copolymerization with norbornene. For this series, the most efficient catalyst system was Pd(acac) 2 + 2Ph 2P(CH 2) 4PPh 2 + 25BF 3OEt 2. The activity of the catalyst system is comparable to that of most active late transition metal catalysts described in the literature. Bidentate phosphines containing bridges larger than 1,4-butane are likely to act as monodentate ligands. The incorporations of flexible alkyl groups onto the main chain of norbornene, as well as copolymerization of 5-alkyl-2-norbornenes with norbornene, represent a useful method for lowering the glass transition temperature ( T g), i.e. improving the processability. The introduction of bidentate phosphine ligand to the Pd(acac) 2 + 25BF 3OEt 2 system switched the carbocationic polymerization mechanism to the coordination Ziegler–Natta polymerization. The simplicity of this catalytic system composition might be of industrial importance.