Halogenation of poly(isobutylene-co-isoprene) (IIR) increases its reactivity towards sulphur and other nucleophiles. Currently brominated (BIIR) and chlorinated (CIIR) derivatives are commercially available; however, an iodinated derivative has been briefly investigated. The effects of leaving group ability and microstructure on the reactivity of halogenated poly(isobutylene-co-isoprene) were studied to put iodobutyl rubber reactivity into context and to compare existing commercial products to their isomeric derivatives.
Polymers containing halomethyl (r-CIIR, r-BIIR, r-IIIR) isomers of butyl rubber were prepared from as-received BIIR to compare the effect of leaving group on thermal stability and reactivity towards nucleophilic substitution. The polymer containing (E,Z)-endo-iodomethyl isomers (r-IIIR) readily underwent nucleophilic substitution at low temperatures; however, it was sensitive towards dehydrohalogenation at temperatures above 65⁰C. At temperatures between 100⁰C and 135⁰C, the bromomethyl derivative (r-BIIR) demonstrated the best balance between reactivity toward nucleophilic substitution and dehydrohalogenation. Exceptional thermal stability at temperatures up to 190⁰C was displayed by the chloromethyl derivative (r-CIIR); however, it was unreactive at low temperatures towards certain nucleophiles. This lack of reactivity shown by r-CIIR was not consistent with all nucleophiles, as reaction dynamics with TBAAc display its variable reactivity towards nucleophilic substitution with results parallel to those of r-BIIR.
Exo-methylene allylic halides (Exo-Br, Exo-Cl) and (E,Z)-endo-halomethyl (r-BIIR, r-CIIR) isomers were vulcanized with sulphur to determine the effect of microstructure on reactivity. Results showed a clear effect of microstructure on the ability to cure with sulphur. While the Exo-Cl isomer has no ability to cure, when rearranged to its (E,Z)-endo-chloromethyl isomer curing occurs readily. Both the Exo-Cl and (E,Z)-endo-bromomethyl isomers readily vulcanize in the presence of sulphur, however Exo-Br cures to a greater extent. / Thesis (Master, Chemical Engineering) -- Queen's University, 2011-09-30 12:55:25.665
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/6819 |
| Date | 03 October 2011 |
| Creators | MCNEISH, JOANNE |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
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