PPV Polymerization through the Gilch Route: Diradical Character of Monomers |
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| Authors: | Dr Jelena D Nikolić Dr Sebastian Wouters Dr Julia Romanova Dr Akihiro Shimizu Prof Dr Benoît Champagne Prof Dr Thomas Junkers Prof Dr Dirk Vanderzande Prof Dr Dimitri Van Neck Prof Dr Michel Waroquier Prof Dr Veronique Van Speybroeck Prof Dr Saron Catak |
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| Institution: | 1. Center for Molecular Modeling, Ghent University, Technologie Park 903, Zwijnaarde, 9052 (Belgium);2. Faculty of Science, University of Kragujevac, 12 Radoja Domanovi?a, 34000 Kragujevac (Serbia);3. Current address: Department of Chemistry, Princeton University, Frick Chemistry Laboratory, Princeton, New Jersey 08544 (USA);4. Laboratoire de Chimie Théorique, University of Namur, Rue de Bruxelles 61, 5000 Namur (Belgium);5. Current address: Advanced Technology Institute, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH. (UK);6. Current address: Department of Synthetic and Biological Chemistry, Kyoto University, Kyoto, (Japan);7. Institute for Materials Research (imo‐imomec), Hasselt University, Martelarenlaan 42, 3500 Hasselt (Belgium);8. IMEC, IMOMEC Ass. Lab., Universitaire Campus, Wetenschapspark 1, 3590 Diepenbeek (Belgium);9. Department of Chemistry, Bogazici University, Bebek, Istanbul, 34342 (Turkey) |
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| Abstract: | Despite various studies on the polymerization of poly(p‐phenylene vinylene) (PPV) through different precursor routes, detailed mechanistic knowledge on the individual reaction steps and intermediates is still incomplete. The present study aims to gain more insight into the radical polymerization of PPV through the Gilch route. The initial steps of the polymerization involve the formation of a p‐quinodimethane intermediate, which spontaneously self‐initiates through a dimerization process leading to the formation of diradical species; chain propagation ensues on both sides of the diradical or chain termination occurs by the formation of side products, such as 2.2]paracyclophanes. Furthermore, different p‐quinodimethane systems were assessed with respect to the size of their aromatic core as well as the presence of heteroatoms in/on the conjugated system. The nature of the aromatic core and the specific substituents alter the electronic structure of the p‐quinodimethane monomers, affecting the mechanism of polymerization. The diradical character of the monomers has been investigated with several advanced methodologies, such as spin‐projected UHF, CASSCF, CASPT2, and DMRG calculations. It was shown that larger aromatic cores led to a higher diradical character in the monomers, which in turn is proposed to cause rapid initiation. |
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| Keywords: | density functional calculations diradicals polymerization radicals reaction mechanisms |
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