Temperature dependence of copolymerization parameters in ethene/1-octene copolymerization using homogeneousrac-Me2Si(2-MeBenz[e]Ind)2ZrCl2/MAO catalyst

Abstract

Ethene was copolymerized with 1‐octene using homogeneous MAO‐activated rac‐Me2Si(2‐MeBenz[e]Ind)2ZrCl2 at constant ethene concentration with temperature varying between 0 and 60°C to determine a temperature dependence of copolymerization parameters. At constant 1‐octene and ethene concentration (constant ethene/1‐octene feed molar ratio) 1‐octene incorporation decreased with increasing temperature. Furthermore, when ethene/1‐octene molar ratio was varied by varying the temperature keeping 1‐octene concentration and ethene pressure constant, increasing temperature accounted for lower molecular masses without affecting 1‐octene incorporation. An explanation for the observed temperature dependence of the copolymerization parameters is presented, considering the solution‐enthalpy of the gaseous ethene in the solvent. In all cases amorphous poly(ethene‐co‐1‐octene) with 1‐octene content varying between 20 and 40 mol % was obtained. © 1997 John Wiley & Sons, Inc.

Phenoxide-Modified Half-Titanocenes Supported on Star-Shaped ROMP Polymers as Catalyst Precursors for Ethylene Copolymerization

“…It is worth noting that the 1-hexene contents in the resultant copolymers, which were estimated by 13 C NMR spectra (described below, Figure ), prepared by star 1 (38.2 mol %, run 20) were slightly higher than those by 1′-Cl (32.7 mol %, run 28), and poly­(NBE)-Ti (33.7 mol %, run 23) . As was observed for 1′-Cl , the 1-hexene contents increased upon increasing the polymerization temperature (25 → 50 °C; 41.7 and 42.0 mol %, runs 24 and 25); this is a trend opposite to that of the ordinary metallocene catalysts, for which 1-hexene (α-olefin) incorporation in the ethylene copolymerization is strongly influenced by the polymerization temperature (decreased at high temperature). ,, These clearly indicate that unique characteristics in the homogeneous system ,, can be preserved even in the star polymer supported catalyst ( star 1 ).…”

“…These values are close to those for the unsupported Cp*TiCl 2 (O-2,6- i Pr 2 C 6 H 3 ) ( 1′-Cl , 2.69, run 28) − , and poly­(NBE)-Ti (2.64, run 23) but smaller than those for the linked half-titanocene [Me 2 Si­(C 5 Me 4 )­(N t Bu)]­TiCl 2 ( r E = 3.42), , which has been known to be an efficient catalyst for ethylene copolymerization. ,, As observed in the unsupported catalyst ( 1′-Cl ), − , the r E value for star 1 was not affected by the polymerization temperature. As described above, this is a trend opposite to that for the ordinary metallocene catalysts, in which the 1-hexene (α-olefin) incorporation is strongly influenced by the polymerization temperature ( r E value increases at high temperature). ,, …”

“…Figure shows a selected 13 C NMR spectrum for the resultant polymers prepared in the ethylene/1-hexene copolymerization by star 1 –MAO catalyst (run 24). All resonances could be assigned according to previous reports, − ,,, and resonances corresponding to 1-hexene isolated and alternating incorporations (alternating 1-hexene insertion, shown by T EHE , αγ, and ββ in Figure ) in addition to the repeated insertion (shown by T HHE and αα) were observed in the spectrum. These results thus clearly indicate that the resultant polymer is poly­(ethylene- co -1-hexene) with random 1-hexene incorporation, as described below.…”

“…Moreover, star 1 exhibited efficient 1-hexene incorporation in ethylene/1-hexene copolymerization, affording the copolymers with unimodal molecular weight distributions. Importantly, star 1 showed rather better 1-hexene incorporation in comparison to the unsupported catalyst Cp*TiCl 2 (O- i Pr 2 C 6 H 3 ) ( 1′-Cl ) − , and poly­(NBE)-Ti , whereas the r E values in these catalysts are close ( r E = 2.36–2.80) and small in comparison to the ordinary linked half-titanocene [Me 2 Si­(C 5 Me 4 )­(N t Bu)]­TiCl 2 ( r E = 3.42). , The r E values by star 1 were not affected by the polymerization temperature, which is a trend opposite to that for ordinary metallocene catalysts. ,, Their microstructure analysis revealed that this would be due to rather higher r H values leading to a rather higher percentage of a 1-hexene repeat (dyads, HH) sequence.…”

meso- and rac-Diastereomers of 1- and 2-tert-Butyldimethylsiloxy- Substituted Ethylenebis(indenyl)zirconium Dichlorides for Formation of Short- and Long-Chain Branched Polyethene

“…This indicates that 1-hexene had a tendency toward isolated monomer insertion along polymer chains. A comparison with literature values reveals that the comonomer reactivites of meso-1 and meso-2 are comparable to that of racdimethylsilylenebis(benz[e]indenyl)zirconium dichloride, 41 which is considered to be a highly efficient copolymerization catalyst. The improved copolymerization ability of the meso-catalysts over their racemic congeners is probably steric in origin, although difficult to rationalize due to the additional steric hindrance induced by the siloxy substituents.…”