Molecular Weight and Functionality Determination of Polyisobutylenes Containing Tertiary Chlorine Chain Ends by Thermal Dehydrochlorination |
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| Authors: | Béla Iván Joseph P Kennedy Tibor Kelen Ferenc Tüdos |
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| Institution: | 1. Institute of Polymer Science, The University of Akron , Akron, Ohio, 44325;2. Central Research Institute for Chemistry of the Hungarian Academy of Sciences , 1525 Budapest, POB 17, Hungary |
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| Abstract: | A sensitive thermal dehvdrochlorination method has been used to determine quantitatively the HCl arising from -CH2C(CH3)2Cl endgroups in polyisobutylenes synthesized by BCb as the co-initiator. Quantitative endgroup analyses provided number-average molecular weights, M n and functionality, F n. Select M n data obtained by this endgroup analysis is in agreement with those obtained by osmometry, GPC, and NMR techniques; indeed, M n's obtained by this dehydrochlorination technique appears to be more accurate (2-3% error) than conventional methods (～5-10% error). The rate of HCl loss from -CH2C(CH3)2Cl termini is first order in HCl with an ΔEa 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 -CH2C(CH3)2CH2C(CH3)2Cl endgroup. These studies quantitatively substantiate earlier conclusions in regard to the mechanism of endgroup formation in BC13 coinitiated isobutylene polymerization. |
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