Reactive Ionomers: N-vinylimidazolium Bromide Derivatives of Poly(isobutylene-co-isoprene) and Poly(isobutylene-co-para-methylstyrene)
Ozvald, Adam Michael
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Ionomers bearing reactive ion-pair functionality are a novel class of materials that have been prepared. The N-alkylation of N-vinylimidazole by poly(isobutylene-co-isoprene) produced the reactive ionomer product in good yield, through a solvent-borne process. Solvent-free conditions can also be used to produce reactive ionomers by the N-alkylation of N-vinylimidazole by poly(isobutylene-co-para-methylstyrene). Characterization of these derivatives was carried out with the assistance of model compounds, and showed excellent agreement with 1H NMR spectra. These reactive ionomers readily crosslink with peroxide at elevated temperatures and in the absence of peroxide they have excellent thermal stability. The amount of crosslinking can be altered based on the vinyl content of the material, to target various applications. N-alkylation of N-vinylimidazole can be carried out concurrently with a non-reactive N-alkylimidazole to achieve desired vinyl contents and tailor the physical properties of these materials. These materials contain both ionic and covalent crosslink networks, and this hybrid network structure provides these materials with unique crosslink structures and stress relaxation properties. Conventional rubber fillers are compatible with these novel reactive ionomers. Carbon black and precipitated silica have no adverse effects on the peroxide crosslinking of the elastomers and a constant peroxide loading can be used regardless of the filler loading. Payne analysis shows good filler dispersion at low filler loading; however, there is some evidence of reticulate filler network formation at high filler loadings.