Copolymerizations of ethylene with 1-hexene overansa-metallocene diamide complexes

Abstract

We have performed copolymerizations of ethylene with 1-hexene using various ansa-metallocene compounds in the presence of the non-coordinative [CPh 3 ][B(C 6 F 5 ) 4 ] ion pair as a cocatalyst. The metallocenes chosen for this study are isospecific metallocene diamide compounds, rac-(EBI)Zr(NMe 2 ) 2 [1, EBI = ethylene-1,2-bis(1-indenyl)], rac-(EBI)Hf(NMe 2 ) 2 (2), rac-(EBI)Zr(NC 4 H 8 ) 2 (3), and rac-(CH 3 ) 2 Si(1-C 5 H 2 -2-CH 3 -4-t C 4 H 9 ) 2 Zr(NMe 2 ) 2 (4), and syndiospecific metallocene dimethyl compounds, ethylidene(cyclopentadienyl)(9-fluorenyl) ZrMe 2 [5, Et(Flu)(Cp)ZrMe 2 ] and isopropylidene(cyclopentadienyl)(9-fluorenyl)ZrMe 2 [6, iPr(Flu)(Cp)ZrMe 2 ]. The copolymerization rate decreased in the order 4 > 1 ~ 3 > 2 > 5 > 6. The reactivity of 1-hexene decreased in the order 2 > 6 > 1 ~ 3 ~ 5 > 4. We characterized the microstructure of the resulting poly(ethylene-co-1-hexene) by 13 C NMR spectroscopy and investigated various other properties of the copolymers in detail.

Stepwise synthesis of a Zr–C–Si main chain polymer precursor for ZrC/SiC/C composite ceramics

“…It was thus worthy to deeply analyze the polymerization mechanism, namely the role of Cp 2 Zr( ii ) and ·MgCl active species in constructing a polymeric chain. Since zirconocene compounds are commonly used as olefin polymerization catalysts, 24–26 we believed the mechanism of coordination insertion polymerizations of 1-olefin by metallocenes 18,19 would inspire our understanding on the role of Cp 2 Zr( ii ) in creating a polymeric structure in PZCS-1, and the synthesis path was shown in Fig. S1c.…”

Copolymerization of ethylene and 1-hexene using (n-BuCp)2ZrCl2 catalyst activated by the cross-linked MAO supported cocatalyst

“…There have been many efforts towards finding more efficient catalysts to produce copolymers having desired physical properties. [7][8][9] Ziegler-Natta catalysts produce copolymers with wide molecular weight distribution (MWD) and short chain branching distribution (SCBD) because of multiple active sites. In contrast, homogeneous metallocenes are single-site catalysts and produce very uniform copolymers with a narrow MWD and SCBD.…”