ISOBUTYLENE-RICH IMIDAZOLIUM IONOMERS: INFLUENCE OF ION-PAIR DISTRIBUTION AND COUNTER-ANION STRUCTURE

Abstract

ABSTRACT New chemistry for overcoming the limitations of nonpolar elastomers is detailed, with particular emphasis on improving interfacial adhesion and the intensity of polymer–filler interactions. The chemical modification of brominated poly(isobutylene-co-isoprene) and brominated poly(isobutylene-co-para-methyl styrene) is used to introduce small amounts of imidazolium bromide functionality. Unlike conventional isobutylene-rich elastomers, ionomer derivatives bearing vinylimidazolium bromide groups are peroxide curable. The ultimate cross-link density, along with accompanying thermoset properties, can be tailored by changing the amount and distribution of N-vinylimidazolium and N-butylimidazolium functionality. Moreover, the counteranion can be exchanged from bromide to sulfonate or vinylsulfonate to further optimize adhesive, tensile, and stress relaxation properties. Bromide exchange anionic montmorillonite clay platelets can yield thermoset ionomer nanocomposites with a high degree of reinforcement despite a relatively low filler loading.