Poly(propene-co-norbornene)s with high molar masses, tunable norbornene contents and properties, in high yield by ketimide-modified half-titanocene catalysts

Abstract

The ketimide-modified half-titanocene catalysts, Cp’TiCl₂(N=CtBu₂ [Cp’ = C₅H₅(1), C₅Me₅ (2), Me₃SiC₅H₄ (3)], afforded high molecular weight copolymers of propene (P) and norbornene (N) with efficient N incorporation in the presence of MAO. The poly(P-co-N)s obtained were studied in detail by determining microstructure and comonomer contents by ¹³C-NMR spectra, molar masses, thermal and mechanical properties. The ketimide Cp’TiCl₂(N=CtBu₂) catalysts 1 and 3 exhibited higher catalytic activities and yielded the copolymers with higher N contents and molar mass than the ketimide-modified Cp*TiCl₂(N=CtBu₂) (2); the resultant copolymer by catalyst 1 contained 61.7 mol % of N and M_w equal to 657 kg mol^-1 possessing uniform composition. The copolymers show very different tensile behaviours passing from ductile and tough materials to stiff and fragile ones as N content increases.