In this study, we examined various alkylaluminums, including triethylaluminum (TEA), triisobutylaluminum (TIBA), and diethylaluminum chloride (DEAC), as cocatalysts for the activation of ethylene polymerizations in the presence of a fluorinated Fujita group invented titanium (FI-Ti) catalyst, bis[N-(3-tert-butylsalicylidene)-2,3,4,5,6-pentafluoroanilinato] titanium(IV) dichloride (complex 1). DEAC, because of the strong Lewis acidity, was an efficient cocatalyst for activating complex 1 for the ethylene polymerizations, whereas TEA and TIBA as cocatalysts could hardly polymerize ethylene. The effects of the polymerization temperature and Al/Ti molar ratio on the formation of active species, properties, and molecular weight of the resulting polyethylene were investigated. In the complex 1/DEAC catalyst system, the oxidation states of Ti active species were determined by electron paramagnetic resonance. The results demonstrated that Ti(IV) active species were inclined to polymerize ethylene and yielded high-molecular-weight polyethylene. Comparatively, Ti(III) active species resulted from the reduction of Ti(IV) by DEAC and afforded oligomers. Moreover, the bigger steric bulk for the cocatalysts was necessary to achieve ethylene living polymerization with the fluorinated FI-Ti catalyst. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
If you can't find a tool you're looking for, please click the link at the top of the page to "Go to old article view". Alternatively, view our Knowledge Base articles for additional help. Your feedback is important to us, so please let us know if you have comments or ideas for improvement.