Prospects\nfor the Use of Al/Mg Cocatalysts (Alk<sub><i>n</i></sub>AlCl<sub>3</sub>–<i><sub>n</sub></i> + Alk<sub>2</sub>Mg) in the Polymerization of Olefins.\nStudies of the Int

Based on previously accumulated experimental material\non the use\nof {<i>n</i>Et<sub>2</sub>AlCl + Bu<sub>2</sub>Mg} mixtures\nfor the activation of Ti postmetallocene precatalysts for ethylene\npolymerization, an attempt is made to find the reason for the universal\nactivating ability of such cocatalysts by analyzing the chemical processes\noccurring during the interaction of alkylaluminum chlorides and dibutylmagnesium. <sup>1</sup>H and <sup>27</sup>Al NMR spectroscopy data indicate that\nin nonsolvating media the formation of ionic products (with which\nearlier the unique activating ability of Al/Mg activators was associated)\ndoes not occur. The “true” Al/Mg cocatalysts are uncharged\nadducts of MgCl<sub>2</sub> with alkylaluminum chlorides and/or trialkylaluminum.\nIt was shown that all used Al/Mg cocatalyst compositions are capable\nof activating a model titanium dichloride complex with a saligenin\nligand with varying efficiencies. The product of the ethylene polymerization\nis an ultrahigh molecular weight polymer (<i>M</i><sub>v</sub> from 1.1 to 5.1 × 10<sup>6</sup> Da); the latter is evidenced\nby the possibility of solid-phase processing of nascent polymer powders\ninto high-strength, high-modulus tapes (breaking strength up to 2.4\nGPa and elastic modulus up to 112 GPa).