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

L´objectif du travail présenté dans ce manuscrit consiste à conserver les bonnes propriétés mécaniques du poly(butadiène) dihydroxytéléchélique (PBHT) tout en améliorant sa stabilité. Un des principaux verrous techniques de cette approche réside dans le fait que les doubles liaisons responsables la flexibilité du matériau sont également la cause de son vieillissement par oxydation. Les solutions proposées reposent sur l´utilisation de la métathèse comme outils de synthèse de polymères insaturés. Deux grandes voix de synthèse ont été étudiées : la polymérisation par ouverture de cycle via métathèse (ROMP) ainsi que la dépolymerisation fonctionnalisante (ADMET). Ces deux approches bien que prometteuses n’ont pas permis de sortir de la relation ciseau existante entre flexibilité et stabilité. Finalement, une solution basée sur le mélange entre deux polymères dihydroxytéléchéliques de basse température de transition vitreuse – poly(butadiene) et poly(isobutylene) a permis de répondre dans une certaine mesure aux cahier des charges. En parallèle a ces parties synthèses, une étude physique des relations structure-propriétés visant à améliorer la stabilité des oligomères a été apporté par mesure rhéologique du temps critique de réticulation. / The work reported in the following document is aiming at maintaining the good mechanical properties of diHydroxyTelechelic PolyButadiene HTPB while improving its stability. The major challenge of this approach is that the unsaturations responsible for the outstanding flexibility of the material are also rather sensitive to oxidation. The solutions presented in this study are based on the use of metathesis reactions as a tool for the design of new difunctional unsaturated oligomers. Two functionalization techniques have been investigated, on the one hand, the Ring Opening Methathesis Polymerisation (ROMP) and, on the other hand, the depolymerisation via Acyclic Diene METathesis (ADMET). Although promising, the latters proved to fall into the vicious circle consisting in simultaneously increasing the stability while losing the flexibility. Finally, a blending concept based on the mixture of two dihydroxytelechelic polymers, namely, poly(isobutylene) and poly(butadiene), could enable us to achieve our initial goal. In addition to the chapters focusing on polymer chemistry and synthesis, a physical study of the parameters influencing the aging of unsaturated oligomers have been set-up and the properties relationship using measurements of the critical time.