Ethylene polymerization was conducted with bis(cyclopentadienyl)zirconium dichloride (1) and racdimethylsilylenebis(indenyl)zirconium dichloride (2) combined with trialkylaluminum (AlR3; R = methyl (Me), ethyl (Et), isobutyl (iBu))/triphenylcarbenium tetrakis(pentafluorophenyl)borate (Ph3CB(C6F5)4) or tris(pentafluorophenyl)borane (B(C6F5)3) to study the effect of cocatalysts on polymerization rate (R(p)). When AlMe3 was used, no activity or very low activity was observed with both zirconocenes regardless of the borane compounds used. The replacement of AlMe3 to AlEt3 or AliBu3 with 1-AlR3/Ph3CB(C6F5)4 caused polymerization and induction time was observed to reach the maximum R(p). Especially in the case of using AlEt3, it took about 30 min to show the activity. When B(C6F5)3 was used, AlEt3 was not effective but AliBu3 gave the highest activity among all the combinations of AlR3 and the borane compounds. In the case of polymerization with 2 using Ph3CB(C6F5)4, high activity was observed with both AlEt3 and AliBu3 without any induction period. When B(C6F5)3 was used instead of Ph3CB(C6F5)4, very low activity was observed with AlEt3. On the other hand, high activity was observed with AliBu3, and the maximum R(p) was found at the beginning of the polymerization. The effect of AlR3 on the formation of active species was discussed based on these results.
- Cation- forming reagent
- Ethylene polymerization
- Zirconocene catalyst
ASJC Scopus subject areas
- Process Chemistry and Technology
- Physical and Theoretical Chemistry