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Polymers 2018, 10(8), 863; https://doi.org/10.3390/polym10080863

Assignment of Regioirregular Sequences in the 13C NMR Spectrum of Syndiotactic Polypropylene

Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Via Cintia, 80126 Napoli, Italy
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Received: 9 July 2018 / Revised: 1 August 2018 / Accepted: 2 August 2018 / Published: 4 August 2018
(This article belongs to the Special Issue Polymer Stereochemistry)
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Abstract

The 13C NMR microstructure of a polypropylene (PP) sample is a fundamental source of information on its properties, and also a ‘fingerprint’ of the catalytic species used to produce it. Likely due to a much greater technological importance, isotactic polymers (i-PP) have been more thoroughly investigated that syndiotactic ones (s-PP). In this paper, we report the first full assignment of regioirregular sequences in s-PP samples made with two well-known molecular catalysts, namely a Cs-symmetric (cyclopentadienyl)(fluorenyl) ansa-zirconocene and a fluxional bis(phenoxyimine)Ti species. The results shed more light on the mechanism of chain propagation at the two catalysts, and open the door to the investigation of more elusive cases like the formation of s-PP blocks in the presence of multi-sited heterogeneous Ziegler-Natta systems. View Full-Text
Keywords: syndiotactic polypropylene; 13C NMR spectroscopy; regiodefects; high temperature cryoprobe; Cs-simmetric ansa-zirconocenes; bis(phenoxyimine)Ti catalysts syndiotactic polypropylene; 13C NMR spectroscopy; regiodefects; high temperature cryoprobe; Cs-simmetric ansa-zirconocenes; bis(phenoxyimine)Ti catalysts
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Cipullo, R.; Vittoria, A.; Busico, V. Assignment of Regioirregular Sequences in the 13C NMR Spectrum of Syndiotactic Polypropylene. Polymers 2018, 10, 863.

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