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Investigation of the microstructure of poly(propylene) in dependence of the polymerization temperature for the systems i Pr[3‐RCpFlu]ZrCl 2 /MAO, with R = H, Me, Et, i Pr, t Bu, and i Pr[IndFlu]ZrCl 2 /MAO
Author(s) -
Kleinschmidt Ralph,
Reffke Matthias,
Fink Gerhard
Publication year - 1999
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/(sici)1521-3927(19990501)20:5<284::aid-marc284>3.0.co;2-f
Subject(s) - metallocene , polymerization , tacticity , cyclopentadienyl complex , substituent , polymer chemistry , propene , chemistry , stereospecificity , specific rotation , materials science , polymer , catalysis , organic chemistry
With six different metallocenes, namely i Pr[CpFlu]ZrCl 2 I , i Pr[3‐MeCpFlu]ZrCl 2 II , i Pr[3‐EtCpFlu]ZrCl 2 III , i Pr[3‐ i PrCpFlu]ZrCl 2 IV , i Pr[IndFlu]ZrCl 2 V and i Pr[3‐ t BuCpFlu]ZrCl 2 VI propene polymerizations were carried out at different polymerization temperatures. MAO was used as a cocatalyst for all polymerizations. In case of metallocenes II, III and IV an increase in isotacticity with increasing polymerization temperature was observed. This is due to the increased rotation and, as a consequence, to the increased steric demand of the substituent at the cyclopentadienyl residue. With metallocene V a catalyst of in principle the same type was synthesized, but rotation of the substituent is not possible. Here, in the contrary, the assumed effect was observed, that the stereospecificity of the metallocene decreases, while raising the polymerization temperature. In metallocene I there is no rotatory substituent at the cyclopentadienyl residue and therefore a more stereoirregular polymer is formed at higher polymerization temperatures. Metallocene VI produces poly(propylene) with slightly increased isotacticity at higher polymerization temperature.