Electric field effects and electroinitiation in cationic polymerizations

Giusti, P.

doi:10.1002/macp.1974.021750408

Makromol. Chem.

1974

DOI: 10.1002/macp.1974.021750408

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Electric field effects and electroinitiation in cationic polymerizations

P. Giusti

Abstract: The results obtained by various authors in the study of cationic polymerizations carried out in the presence of an electric field of high strength, that we propose to call "electro-influenced polymerizations", are shortly reviewed.The most relevant results obtained in the author's laboratories, for the "electroinfluenced" cationic polymerization of anethole, isobutyl vinyl ether and cyclohexyl vinyl ether with constant or periodically reversed field polarity are illustrated.The analogies between these results … Show more

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Cited by 8 publications

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Persistent problems and recent progress in the field of cationic polymerization

Sigwalt

1974

Makromol. Chem.

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Some of the most important unsolved problems of cationic polymerizations are reviewed together with the most significant progress made recently.In the field of initiation reactions, there are more and more data showing that initiation ofethylenic monomers by Friedel Crafts catalysts does not always necessitate a coinitiator. The different hypotheses already put forward to explain these "direct initiations" are discussed and a new mechanism is proposed. The mechanisms of termination and transfer reactions are also examined.Concerning the mechanisms of propagation reactions, the difficulties in determining the concentration of active centers are outlined. Some progress was made by using stable carbocations as initiators, but some discrepancies between the results are discussed (existence of apparently negative activation energies). The different types of active species in equilibrium are examined, together with the nature of the non dissociated species.The differences between the propagation rate constants over free ions, measured in systems initiated by high energy radiations or more classical cationic initiators, are also discussed. ZUSAMMENFASSUNG:Es wird ein Uberblick gegeben uber die bedeutendsten ungelosten Probleme der kationischen Polymerisation, zusammen mit den wichtigsten neuen Fortschritten.Auf dem Gebiet der Startreaktionen haufen sich die Tatsachen, die darauf hinweisen, daR die Initiierung von Athylen-Monomeren durch Friedel-Crafts-Katalysatoren nicht in allen Fallen eines Coinitiators bedarf. Bereits vorgebrachte Hypothesen, die diese ,,direkte Initiierung" erklaren, werden diskutiert, und ein neuer Mechanismus wird vorgeschlagen. AuRerdem werden der Abbruch-und der Ubertragungs-Mechanismus untersucht.Die Diskussion des Mechanismus der Wachstumsreaktionen setzt sich mit den Schwierigkeiten der Bestimmung der Konzentration der aktiven Zentren auseinander. Ein gewis-Makromol. Chem. 175, No. 4, April 1974 1017 P. Sigwalt ser Fortschritt wurde durch Verwendung stabiler Carbokationen als Initiatoren erzielt, jedoch einige Widerspriiche aus verschiedenen Ergebnissen (das Vorhandensein scheinbar negativer Aktivierungsenergien) werden diskutiert.Die verschiedenen Typen aktiver Spezies im Gleichgewicht werden untersucht, zusammen mit der Natur der nicht dissoziierten Spezies. Die Unterschiede in den Konstanten der Fortpflanzungsgeschwindigkeit iiber freie Ionen, die in Systemen gemessen wurden, die durch Bestrahlung mit hoher Energie oder durch klassische kationische Initiatoren gestartet wurden, werden ebenfalls diskutiert.* This problem is discussed in another paper of this symposium; A. Ledwith, Makromol. Chem. 175, 11 17 (1974).

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Persistent problems and recent progress in the field of cationic polymerization

Sigwalt

1974

Makromol. Chem.

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Electric field effects in the polymerization of α‐methylstyrene

1978

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We here report the boron trifluoride diethyletherate initiated polymerization of a-methylstyrene in 1,2-dichIoroethane. With platinum foil electrodes and an applied electric field of 1-3 kV/cm, the initial rate of disappearance of monomer is the same in the absence or presence of the electric field. The rate of formation of polymer at high conversions, however, decreases when the electric field is imposed. The NMR, UV absorption, and fluorescence spectra of the polymers are affected by the field, whereas the IR, ESCA spectra, and melting point of the polymer are unaffected by the field. To probe the reasons for these field effects, we obtained oxidation and reduction potentials of monomer, solvent, and initiator by polarographic or cyclic voltammetric methods. All the components of the system were easily reduced or oxidized. Also, when the anode and cathode were separated by a sintered glass disk, the amount of polymer formed in the anode compartment was greater than that in the cathode compartment. These results suggest that the observed electric field effects are due to electrochemical reactions rather than to the second Wien effect.Recently Ise et al. '-'

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Electroinitiated ionic polymerization

Giusti

1975

J. polym. sci., C Polym. symp.

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A classification of the electroinitiation processes which takes into account the nature of the electrodic processes undergone by the different substances present in the reaction mixture is proposed. Some of the most recent results obtained in the author's laboratories on both electroinitiated and electroinfluenced polymerizations are briefly described and discussed. An algebraic treatment is also illustrated, which stresses the importance of the diffusion phenomena thus far neglected by most researchers. The theoretical results of this treatment are shown to closely agree with the experimental results.

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Electric field effects and electroinitiation in cationic polymerizations

Cited by 8 publications

References 28 publications

Persistent problems and recent progress in the field of cationic polymerization

Persistent problems and recent progress in the field of cationic polymerization

Electric field effects in the polymerization of α‐methylstyrene

Electroinitiated ionic polymerization

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