1
|
Penczek S, Szymanski R, Duda A. Polymerizations with contribution of covalent and ionic species. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/masy.19950980116] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
2
|
Charleux B, Moreau M, Vairon JP, Hadjikyriacou S, Faust R. Model kinetic study of TiCl4
-induced ionization of polyisobutene capped with diphenylethylene application to the synthesis of block copolymers. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/masy.19981320105] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
3
|
|
4
|
Vairon JP, Rives A, Bunel C. Direct observation and stability of active species in cationic polymerization: A reexamination of the polymerization of styrene initiated by triflic acid. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/masy.19920600109] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
5
|
Leiterer J, Panne U, Thünemann AF, Weidner SM. Container-less polymerization in acoustically levitated droplets: an analytical study by GPC and MALDI-TOF mass spectrometry. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2011; 3:70-73. [PMID: 32938112 DOI: 10.1039/c0ay00390e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Molecular masses and end groups of polystyrene (PS) formed in a novel container-less polymerization strategy, based on levitated droplets in an acoustic trap, were determined by Gel Permeation Chromatography (GPC) and Matrix-assisted Laser Desorption/Ionization Time of Flight Mass spectrometry (MALDI-TOF MS).
Collapse
Affiliation(s)
- Jork Leiterer
- BAM Bundesanstalt für Materialforschung und -prüfung, Richard-Willstätter-Str. 11, 12489, Berlin, Germany.
| | - Ulrich Panne
- BAM Bundesanstalt für Materialforschung und -prüfung, Richard-Willstätter-Str. 11, 12489, Berlin, Germany.
- Humboldt-Universitaet zu Berlin, Department of Chemistry, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | - Andreas F Thünemann
- BAM Bundesanstalt für Materialforschung und -prüfung, Richard-Willstätter-Str. 11, 12489, Berlin, Germany.
| | - Steffen M Weidner
- BAM Bundesanstalt für Materialforschung und -prüfung, Richard-Willstätter-Str. 11, 12489, Berlin, Germany.
| |
Collapse
|
6
|
Cozens FL, Kanagasabapathy VM, McClelland RA, Steenken S. Lifetimes and UV-visible absorption spectra of benzyl, phenethyl, and cumyl carbocations and corresponding vinyl cations. A laser flash photolysis study. CAN J CHEM 1999. [DOI: 10.1139/v99-210] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Benzyl (4-MeO, 4-Me, and 4-methoxy-1-naphthylmethyl), phenethyl (4-Me2N, 4-MeO, 3,4-(MeO)2, 4-Me, 3-Me, 4-F, 3-MeO, 2,6-Me2, parent, and 4-methoxy-1-naphthylethyl) and cumyl (4-Me2N, 4-MeO, 4-Me, parent) cations have been studied by laser flash photolysis (LFP) in 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoroisopropanol (HFIP). In most cases styrene or α-methylstyrene precursors were employed for the phenethyl and cumyl ions, the intermediate being obtained by solvent protonation of the excited state. Benzyl cations were generated by photoheterolysis of trimethylammonium and chloride precursors. While a 4-MeO substituent provides sufficient stabilization to permit observation of cations in TFE, cations with less stabilizing substituents usually require the less nucleophilic HFIP. Even in this solvent, the parent benzyl cation is too short-lived (lifetime <20 ns) to be observed. When generated in HFIP, phenethyl cations can be seen to react with unphotolyzed styrene, giving rise to dimer cations that are observed to grow in as the initial phenethyl cation decays. The dimer cations, in common with the oligomer cations seen in cationic styrene polymerization, have a λmax 15-20 nm higher than the monomer and react with both solvent and styrene several orders of magnitude more slowly. This stabilization relative to the phenethyl may reflect an interaction with the aryl group present at the gamma-carbon. Cations 4-MeOC6H4C+(R)-CH3 (R = Me, Et, i-Pr, t-Bu, cyclopropyl, C6H5, 4-MeOC6H4) were generated in TFE via the photoprotonation route. The alkyl series shows that steric effects are important in the decay reaction. The cation with R = cyclopropyl is a factor of 1.5 less reactive than the cation where R = phenyl. Several vinyl cations have also been generated by photoprotonation of phenylacetylenes. ArC+=CH2 has a reactivity very similar to that of its analog ArC+H-CH3, the vinyl cation being slightly (factors of 2-5) shorter-lived. For the various series of cations, including vinyl, substituents in the aryl ring have a consistent effect on the λmax, a shift to higher wavelength relative to hydrogen of 15 nm for 4-Me, 30 nm for 4-MeO, and 50 nm for 4-Me2N.Key words: photogenerated carbocations, carbocation lifetime, styrene, photoprotonation.
Collapse
|