Ethylene-norbornene copolymerization by carbon nanotube-supported metallocene catalysis: generation of high performances polyolefinic nanocomposites

Homogeneous surface coating of multi-walled carbon nanotubes is achieved for the first time by in situ copolymerization of ethylene (E) and 2-norbornene (N) as catalyzed directly from the nanotube surface previously treated by a highly active metallocene-based complex, i.e., rac-Et(Ind)2ZrCl2/MMAO-3A. The copolymerization reaction allows for the destructuration of the native nanotube bundles, which upon further melt blending with an ethylene-vinyl acetate copolymer (27 wt.-% vinyl acetate) matrix, leads to high-performance polyolefinic nanocomposites. The microstructural analysis of the surface-coating copolymer was carried out by 13C NMR spectroscopy and allowed determination of the actual N content incorporated along the chains. Depending on the experimental conditions used (e.g., E pressure, solvent, feed N concentration) the relative quantity of E-N copolymer can be tuned, as well as the N content in the formed copolymers and accordingly their glass transition temperature.