Ethylene-norbornene copolymerization by rare-earth complexes and by carbon nanotube-supported metallocene catalysis

E-N copolymerization with a number of half-sandwich rare-earth metal compounds [M(?5-C5Me4SiMe2R)(?1-CH2SiMe3)2(L)] (M?=?Sc, Y, Lu) has been achieved. Mainly atactic alternating EN copolymers are obtained with all catalytic systems. Interestingly, copolymers arising from [Sc(?5-C5Me4SiMe2C6F5)(?1-CH2SiMe3)2(THF)]/[/[Ph3C][B(C6F5)4] possess narrower molar mass distributions than those from [Sc(?5-C5Me4SiMe3)(?1-CH2SiMe3)2(THF)]/[Ph3C][B(C6F5)4]. In addition, homogeneous surface coating of multi-walled carbon nanotubes is accomplished for the first time by in situ E-N copolymerization as catalyzed by rac-Et(Ind)2ZrCl2/MMAO-3A anchored onto the carbon nanotube surface. The copolymerization reaction allows for the destructuration of the native nanotube bundles. The relative quantity of EN copolymer can be tuned up as well as the norbornene content in the formed copolymers and accordingly their glass transition temperature. By melt blending with an ethylene-vinyl-co-acetate copolymer (27 wt.-% vinyl acetate comonomer) matrix, high performance polyolefinic nanocomposites are obtained.