On the contribution of different reaction routes to polymer formation in reversible polymerization. Oxepane and 1,3-dioxolane polymerization cases
✍ Scribed by Ryszard Szymanski
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 633 KB
- Volume
- 5
- Category
- Article
- ISSN
- 1022-1344
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✦ Synopsis
The analysis of the contributions of different propagation routes in reversible polymerization was performed. It was shown by computer simulations that material and kinetic contributions of the given propagation route can differ. An especially large difference between these quantities was found in the simulated polymerization of 1,3-dioxolane. This allowed to explain the unexpectedly large difference between the values of the apparent rate constant of propagation and the estimated rate constant of the corresponding elementary reaction of propagation in the polymerization of 1,3-dioxolane. n and leading to active centers of j-th type, ai = X i / C X i is the fraction of active centers -M& (n is the number of types of active species). A change of the type of active center in propagation is most often observed in covalent propagations of cyclic monomers, e. g., i= I kei ...-0 3 -A + 0 3 -...-O-LJ, A-(3)
for which the contribution of covalent propagation was analyzed by several authors When, however, propagations are reversible, then the equstion arises if Eq. ( 2) is still correct. The problem of computing the contribution of covalent propagation was analyzed p r e v i o u ~l y ~-~) .
In this paper it is shown that the contribution of the given propagation route in reversible polymerization can be meant differently depending on the assumed definition, and a propositon of systemizing the arising problems, allowing to avoid misunderstanding, is given. Moreover, in order to visualize better the