Anionic polymerization of styrene in tetrahydropyran under an electric field periodically reversed
✍ Scribed by G. Pizzirani; M. Di Maina; M. Palla; P. Giusti
- Publisher
- Elsevier Science
- Year
- 1977
- Tongue
- English
- Weight
- 378 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0014-3057
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✦ Synopsis
A~traet--The anionic polymerization of living polystyryl di-sodium salt was investigated in tetrahydropyran (THPI at 25:. under high vacuum either in the absence or in the presence of an electric field with either constant or periodically reversed polarity over a wide range of frequencies. The application of an electric field with constant polarity increased the apparent rate constant of propagation. It increased in fact the term k~_~ K~ 2 (where k~_~ is the rate constant of propagation of free ions and K o is the dissociation constant of ion-pairs) whereas it left unaffected the rate constant of propagation of ion-pairs k~± t. The observed effect of the field did not change appreciably if the polarity of the field was reversed with a frequenc) up to ca. 0.134 Hz. At frequencies of reversal above ca. 0.16 Hz, the enhancement of the polymerization rate due to the electric field became negligible. The observed field effects are interpreted in terms of electrolytic phenomena and of the possibility of growing macroanions assuming a more extended conformation in which the living ends become more accessible to the monomer.