Reactions of N-Alkylbenzaldimines with Brominated Poly(isobutylene-co-isoprene): New Delayed Onset Cure Chemistry

Reactions of N-alkylbenzaldimines with allylic bromides are used to prepare bromobutyl thermosets with unique control over cross-linking rates and extents. Whereas the repeated N-alkylation of aliphatic primary amines cross-links brominated poly(isobutylene-co-isoprene) (BIIR) too quickly to support standard rubber compounding and processing operations, imine formulations are shown to be inactive at 100 °C but highly reactive at conventional cure temperatures. Imine activation by direct hydrolysis, Bronsted-acid-catalyzed hydrolysis, and N-alkylation/hydrolysis pathways are examined as are substitutent effects on imine nucleophilicity and BIIR cure performance.