Polymerization of norbornene by modified Ziegler‐catalysts

Abstract

Abstract For the polymerization of norbornene, three modes of reaction have been known: vinyl polymerization (I) and ring‐opening polymerizations giving trans (II) and cis (III) double bonds. In the present study, the polymerization by modified Z IEGLER type catalysts was carried out. Modification was obtained by the addition of several L EWIS base compounds as the third component to the binary system of metal alkyl and titanium tetrachloride. The AlEt 3 /TiCl 4 (2.5/1), AlEt 3 /TiCl 4 (1/1), and LiAlEt 3 Bu/TiCl 4 (2.5/1) systems induce the norbornene polymerization giving polymers consisting mostly of the units (I) + (II), (I) and (II), respectively. These three systems were transformed by the addition of some L EWIS bases into the species which give high molecular weight polymers consisting exclusively of the ring‐opened units (II) and (III). The modification by L EWIS base is prominent in the region of the base/TiCl 4 ratio of 2 to 4.