Mechanism of Isomerization in the Cationic Polymerization of Isobutylene
| Autor: | Philip Dimitrov, Jun Hua, Rudolf Faust, Sándor Kéki, Jack Emert |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Isobutylene
chemistry.chemical_classification Olefin fiber Polymers and Plastics Organic Chemistry Cationic polymerization Living cationic polymerization Photochemistry Catalysis Inorganic Chemistry chemistry.chemical_compound Hydrocarbon chemistry Polymer chemistry Materials Chemistry Time-of-flight mass spectrometry Isomerization |
| Zdroj: | Macromolecules. 44:1831-1840 |
| ISSN: | 1520-5835 0024-9297 |
| DOI: | 10.1021/ma102645w |
| Popis: | The complex mechanism of the carbocationic rearrangements leading to a variety of olefin (exo-, endo-, tri-, and tetra-substituted) end groups in the cationic polymerization of isobutylene (IB) catalyzed by ethylaluminum dichloride (EtAlCl2) in nonpolar solvents in the temperature range of −40 to 25 °C was studied by model ionization experiments employing poly(isobutylene chloride) (PIB-Cl) of low molecular weight (Mn ∼ 1000−2000) obtained by living cationic polymerization. Ionizations were performed with EtAlCl2 in hydrocarbon media to mimic a conventional cationic polymerization of IB, but in the presence of a proton trap to suppress reprotonation of the first formed olefin and subsequent decomposition of the resulting PIB cation. In the absence of a proton trap, ionization of PIB-Cl resulted in about 70% of tri-substituted olefin end groups in the studied temperature range. The exo and endo olefin end-group content was negligible. MALDI and APPI TOF MS indicated that the tri-substituted PIB olefins con... |
| Databáze: | OpenAIRE |
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