Copolymerization of norbornene and n-butyl methacrylate catalyzed by bis-(β-ketoamino)nickel(II)/B(C6F5)3 catalytic system

Abstract

Copolymerization of norbornene with n-butyl methacrylate (n-BMA) was carried out with catalytic systems of bis-(β-ketoamino)nickel(II) complexes Ni{RC(O)CHC[N(naphthyl)]CH3}2 (R = CH3, CF3) and B(C6F5)3 in toluene and exhibited high activity for both catalytic systems. Influence of the catalyst structure and comonomer feed content on the polymerization activity as well as on the incorporation rates were investigated. The catalysis was proposed to involve the insertion mechanism of norbornene and n-BMA catalyzed by bis-(β-ketoamino)nickel(II)/B(C6F5)3 catalytic systems, and the decreasing polymerization activity with an increasing content of n-BMA in the feedstock composition could be attributed to the competition of carbonyl group coordination onto the Ni(II) active center instead of the olefin double bond. The reactivity ratios were determined to be r n-BMA = 0.095 and r norbornene = 12.626 by the Kelen–TUdOs method. The copolymer films prepared show good transparency in the visible region. The vinyl-addition copolymerizations of norbornene and n-BMA, catalyzed by bis-(β-ketoamino)nickel(II) complex Ni{RC(O)CHC[N(naphthyl)]CH3}2 (R = CH3, CF3)/B(C6F5)3, led to a significant incorporation percentage of poly(n-butyl methacrylate) in the resulting copolymer with good solvent solubility and transparency. The complex Ni{RC(O)CHC[N(naphthyl)]CH3}2 with R = CF3 substitute exhibit higher catalytic activity than that with R = CH3 substitute in the presence of B(C6F5)3 as cocatalyst for the copolymerization.