Induced changes in the molecular weight of polybutadiene using alkyllithium-alkyl halide complexes
| Autor: | A. F. Halasa, H. E. Adams |
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| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | Journal of Polymer Science Part C: Polymer Symposia. 30:169-179 |
| ISSN: | 1935-3065 0449-2994 |
| DOI: | 10.1002/polc.5070300121 |
| Popis: | It has been demonstrated that gel permeation chromatography is useful in studying the reaction of aliphatic chloride, such as CCl4 and secondary-butyl chloride, with polybutadiene. These materials produce an increase in average molecular weight of the polymer and the concomitant change in distribution assists in verification of the proposed mechanism of reaction. Reaction is assumed to proceed through intermediate formation of radicals. If live polymer is used, both allyl and alkyl radicals are produced. Allyl radicals readily dimerize while alkyl radicals attack double bonds in the backbone of the chain to produce crosslinking. Quite different distributions result from these two reactions. Molecular weight distributions of polymers produced by reacting either CCl4 or secondary-butyl chloride with live polymer indicate the predominant reaction to be dimerization of allyl radicals. On the other hand, the crosslinking reaction occurs exclusively if dead polymer is reacted with secondary butyl chloride. In this case, it is necessary to add a strong base, such as n-butyllithium, to obtain the molecular weight increase. |
| Databáze: | OpenAIRE |
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