Key Words:ETHYLENE POLYMERIZATION; CATALYTIC PERFORMANCE; OLEFIN POLYMERIZATION; BLOCK-COPOLYMERS; BEARING; OLIGOMERIZATION; ACTIVATORS; DISCOVERY; FAMILY; ALKYL
Abstract:The development of metal catalysts with high activity and thermal stability but with the requirement of a small amount of MAO as a cocatalyst is highly desired for polyolefin industrial application. In this contribution, a series of phenoxy-imine-amine compounds were prepared and used as NNO-tridentate ligands (LH1-LH6: LH = 2,6-(R-1)(2)-C6H3-NH-C6H4-N-C-3,5-(R-2)(2)-C6H2-OH; LH1: R-1 = Pr-i, R-2 = Bu-t; LH2: R-1 = Me, R-2 = Bu-t; LH3: R-1 = H, R-2 = Bu-t; LH4: R-1 = F, R-2 = Bu-t; LH5: R-1 = Me, R-2 = H; LH6: R-1 = Me, R-2 = Cl) to support chromium complexes CrCl2L(THF) (Cr1(THF)-Cr6(THF)). Upon activation with only 200 equivalents of Al(MAO), these Cr complexes exhibited extremely high activity toward ethylene polymerization and an unprecedented activity as high as 1.18 x 10(8) g(PE) mol(-1)(Cr) h(-1) was obtained using Cr2(THF)/MAO. Moreover, these Cr catalysts exhibited high thermal stability, with respect to both the activity and the molecular weight. At 100 degrees C, Cr2(THF)/MAO showed a remarkable activity of 1.01 x 10(8) g(PE) mol(-1)(Cr) h(-1) and produced polyethylene with a high molecular weight of 24.6 x 10(4) g mol(-1). Therefore, the newly developed NNO-tridentate Cr complexes exhibiting unprecedented activity and excellent thermal stability but only requiring a small amount of MAO (as low as Al/Cr = 100) as a cocatalyst are very promising in the polyolefin industry.
Volume:13
Issue:13
Translation or Not:no