1. Assignment of Regioirregular Sequences in the 13C NMR Spectrum of Syndiotactic Polypropylene
- Author
-
Antonio Vittoria, Vincenzo Busico, Roberta Cipullo, Cipullo, Roberta, Vittoria, Antonio, and Busico, Vincenzo
- Subjects
Chain propagation ,Materials science ,Polymers and Plastics ,Bis(phenoxyimine)Ti catalyst ,Cs-simmetric ansa-zirconocenes ,010402 general chemistry ,01 natural sciences ,bis(phenoxyimine)Ti catalysts ,Article ,Catalysis ,regiodefects ,lcsh:QD241-441 ,syndiotactic polypropylene ,chemistry.chemical_compound ,13C NMR spectroscopy ,Cyclopentadienyl complex ,lcsh:Organic chemistry ,Tacticity ,high temperature cryoprobe ,Polypropylene ,chemistry.chemical_classification ,010405 organic chemistry ,Cs-simmetric ansa-zirconocene ,Chemistry (all) ,General Chemistry ,Polymer ,Carbon-13 NMR ,Microstructure ,Regiodefect ,0104 chemical sciences ,Crystallography ,chemistry - Abstract
The 13C NMR microstructure of a polypropylene (PP) sample is a fundamental source of information on its properties, and also a &lsquo, fingerprint&rsquo, 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.
- Published
- 2018