Isotactic-specific polymerization of propene with an iron-based catalyst: polymer end groups and regiochemistry of propagation |
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Authors: | Claudio Pellecchia Mina Mazzeo Daniela Pappalardo |
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Institution: | Dipartimento di Chimica, Università di Salerno, I-84081 Baronissi (SA), Italy |
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Abstract: | Prevailingly isotactic poly(propylene) samples were prepared with a homogeneous catalytic system based on a bis(imino)pyridyl Fe(II) derivative and methylaluminoxane. The polymer microstructure is in agreement with Bernoullian statistics of dyad formation, implicating a “chain-end” mechanism of steric control. The latter is operative even at polymerization temperatures as high as +50°C. NMR analysis of polymer end groups indicates that chain growth proceeds via 2,1 monomer insertion. The last two findings are unprecedented for isotactic-specific polymerization of propene and are reasonably related to each other. |
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