Computational mechanistic studies on persulfate assisted p-phenylenediamine polymerization
© 2022 Wiley Periodicals LLC.
| Veröffentlicht in: | Journal of computational chemistry. - 1984. - 43(2022), 19 vom: 15. Juli, Seite 1313-1319 |
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| Weitere Verfasser: | , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2022
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| Zugriff auf das übergeordnete Werk: | Journal of computational chemistry |
| Schlagworte: | Journal Article DFT energy barrier noncovalent interaction p-phenylenediamine polymerization potassium persulfate transition state |
| Zusammenfassung: | © 2022 Wiley Periodicals LLC. p-Phenylenediamine (p-PDA) is a monomer of many important polymers such as kevlar, twaron, poly-p-PDA. Most of the noticed polymers formation is initiated by a free-radical, but their polymerization mechanism is not elucidated computationally. The proposed study helps to fully understand the frequently utilized initiator/oxidant, potassium persulfate (K2 S2 O8 ) role in the aromatic diamines polymerization, which support experimental protocols, and a polymer scope. The formation of the poly-p-PDA is studied with the density functional theory (DFT) B3LYP-D3 functional using experimental polymerization parameters (0°C and aqueous media). K2 S2 O8 initiated free-radical polymerization of p-PDA is studied in detail, taking into account sulfate free-radical (SO4 - )· , SFR, persulfate anion (S2 O8 )2- , PA and K2 S2 O8 cluster, PP. The reaction mechanism is calculated as the conversion of p-PDA to free-radical, the p-PDA free-radical attack to the next p-PDA (dimerization), ammonia extrusion from the dimer adduct, the dimer adduct conversion to the free-radical (completion of p-PDA polymerization cycle) for the polymer chain elongation. Calculations show that the dimerization step is the rate-limiting step with a 29.2 kcal/mol energy barrier when SFR initiates polymerization. In contrast, the PA-assisted dimerization energy barrier is only 12.7 kcal/mol. PP supported polymerization is calculated to have very shallow energy barriers completing the polymerization cycle, i.e., dimerization (TS2K, ∆G‡ = 11.6 kcal/mol) and ammonia extrusion (TS3K, ∆G‡ = 6.7 kcal/mol) |
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| Beschreibung: | Date Revised 13.06.2023 published: Print-Electronic Citation Status PubMed-not-MEDLINE |
| ISSN: | 1096-987X |
| DOI: | 10.1002/jcc.26943 |