Synthesis and Characterization of Isobutylene-Based Ammonium and Phosphonium Bromide Ionomers

Abstract

The preparation of isobutylene-based ionomers through displacement of halide from brominated poly(isobutylene- co -isoprene) (BIIR) by triphenylphosphine (PPh 3 ) and N, N -dimethyloctylamine (DMOA) is demonstrated. While the resulting phosphonium and ammonium bromide salts (IIR-PPh 3 Br and IIR-NR 3 Br, respectively) possess dynamic mechanical properties that are comparable to thermoset vulcanizates, the elastomeric network is the result of ion-pair aggregation. Evidence of intra- and intermolecular aggregation provided by dynamic mechanical and dilute solution viscosity analyses is reinforced by studies of 1 H NMR spin−spin relaxation, which demonstrate the reduced mobility of those polymer chain segments proximal to the phosphonium bromide functionality within IIR-PPh 3 Br.