Novel bidentate phosphine modified Pd(acac)(2)/BF3OEt2 catalyst system for the homopolymerization of alkylnorbornenes and copolymerization with norbornene

Abstract

The Pd(acac)(2) + nPh(2)P(CH2)(m) PPh2 + 25BF(3)OEt(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(2)P(CH2)(4)PPh2 + 25BF(3)OEt(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.), i.e. improving the processability. The introduction of bidentate phosphine ligand to the Pd(acac)(2) + 25BF(3)OEt(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. (c) 2005 Elsevier B.V. All rights reserved.