SYNOPSISPropene was polymerized a t 40°C and 2-bar propene in toluene using methylalumoxane (MAO) activated ra~-Me~Si(Benz[e]Indenyl)~Zr C12 (BI) a n d rac-Me2Si(2-Me-Ben~[e]Indenyl)~ZrCl~ (MBI). Catalyst BI/MAO polymerizes propene with high activity to afford low molecular weight polypropylene, whereas MBI/MAO is less active and produces high molecular weight polypropylene. Variation of reaction conditions such as propene concentration, temperature, concentration of catalyst components, and addition of hydrogen reveals that the lower molecular weight polypropylene produced with BI/MAO results from chain transfer to propene monomer following a 2,l-insertion. A large fraction of both metallocene catalyst systems is deactivated upon 2,l-insertion. Such dormant sites can be reactivated by H2-addition, which affords active metallocene hydrides. This effect of H2addition is reflected by a decreasing content of head-to-head enchainment and the formation of polypropylene with n-butyl end groups. Both catalysts show a strong dependence of activity on propene concentration that indicates a formal reaction order of 1.7 with respect to propene. MBI/MAO shows a much higher dependence of the activity on temperature than BI/MAO. At elevated temperatures, MBI/MAO polymerizes propene faster than BI/ MAO. 0 1995 John Wiley & Sons, Inc.
Cationic metallocene/borate catalysts, generated from
zirconocene dimethyl compounds,
L
n
ZrMe2, and anilinium borate,
[HNMe2Ph]+[B(C6F5)4]-,
were used to polymerize 5-amino-1-pentenes
and one 4-amino-1-butene with dimethyl, diethyl, diisopropyl, or
diphenyl substitution patterns on
nitrogen. The monomer
5-(N,N-diisopropylamino)-1-pentene showed the
highest activity with
Cp*2ZrMe2/borate and was used for all further investigations. The catalytic
system Cp*2ZrMe2/borate was 4
times
more active than the corresponding methylaluminoxane-based system and
180 times more active than
the heterogeneous system,
TiCl3/Al(i-Bu)3. 1-Hexene
and 5-(N,N-diisopropylamino)-1-pentene
were
polymerized with Cp*2ZrMe2 and
rac-ethylenebis(tetrahydroindenyl) zirconium dimethyl,
rac-EB(THI)ZrMe2. Polymerization of both monomers with
Cp*2ZrMe2 displayed similar activities.
Hexene polymerizations with rac-EB(THI)ZrMe2 were
30 times more active than those with aminopentene.
5-(N,N-Diisopropylamino)-1-pentene polymerizations gave rise to isotactic
poly(aminopentene) with C
2
symmetric
catalysts, syndiotactic polymer with a C
s
symmetric catalyst, and atactic polymer with achiral
catalyst
precursors.
Metallocene/borate catalysts, generated from zirconocene dimethyl compounds, L
n
ZrMe2,
and anilinium borate, [HNMe2Ph]+[B(C6F5)4]-, were used to copolymerize 5-N,N-diisopropylamino-1-pentene with 1-hexene and 4-methyl-1-pentene. The selected zirconocenes, bis(pentamethylcyclopentadienyl)zirconium(IV) dimethyl (Cp*2ZrMe2) and rac-ethylenebis(4,5,6,7-tetrahydroindenyl)zirconium(IV)
dimethyl (rac-EB(THI)ZrMe2), provided atactic and isotactic materials, respectively. The isotactic polymers
produced were amorphous or crystalline depending of the monomer. The calculated reactivity ratios for
the copolymerization of 5-N,N-diisopropylamino-1-pentene with 1-hexene and metallocene rac-EB(THI)ZrMe2 indicate that this system approximates an ideal azeotropic copolymerization with r
1 = 1.11
and r
2 = 0.87. Estimates for the reactivity ratios for the copolymerization of 5-N,N-diisopropylamino-1-pentene with 4-methyl-1-pentene were r
1 = 3 and r
2 = 1 for rac-EB(THI)ZrMe2 and r
1 = 5 and r
2 = 0.5
for Cp*2ZrMe2. The polymerization of 1-hexene in the presence of the saturated 1-N,N-diisopropylaminopentane with rac-EB(THI)ZrMe2/borate was compared with analogous copolymerizations of 1-hexene/5-N,N-diisopropylamino-1-pentene. The aminopentene was more effective than the aminopentane in
inhibiting the rate of total monomer conversion, implicating both intra- and intermolecular mechanisms
for inhibition by the amine. Copolymers of 4-methyl-1-pentene/5-N,N-diisopropylamino-1-pentene produced
with rac-ethylenebisindenyl zirconium(IV) dimethyl (rac-EBIZrMe2)/borate have higher decomposition
temperatures with increasing amounts of aminopentene. This copolymer can be protonated with HCl to
yield a methanol-soluble material.
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