A sensitive thermal dehydrochlorination method has been used to determine quantitatively the HC1 arising from -CH2C(CH3)2Cl endgroups in polyisobutylenes synthesized by BCl3 as the co-initiator. Quantitative endgroup analyses provided number-average molecular weights, Mn, and functionality, Fn. Select data obtained by this endgroup analysis is in agreement with those obtained by osmometry, GPC, and NMR techniques; indeed, Mn's obtained by this dehydrochlorination technique appears to be more accurate (2-3% error) than conventional methods (-5- 10% error). The rate of HC1 loss from -CHZC(CH-)ZC-termini is first order in HCl with an AEa of 19.1 kcal/mol in the 170-200 C range. This relatively low activation energy is most likely due to internal strain in the -CHZC(CH-)ZCHZC-(CH3)zCl endgroup. These studies quantitatively substantiate earlier conclusions in regard to the mechanism of endgroup formation in BC13 coinitiated isobutylene polymerization.
|Number of pages||10|
|Journal||Journal of Macromolecular Science: Part A - Chemistry|
|Publication status||Published - Jan 1981|
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