Functional group tolerance of AOTEMPO-mediated peroxide cure chemistry

Abstract Delayed onset formulations for the peroxide-initiated crosslinking of a range of commodity polymers are described. 4-Acryloyloxy-2,2,6,6,-tetramethylpiperidin- N -oxyl (AOTEMPO) is effective for controlling the crosslinking dynamics and yields of linear low density polyethylene (LLDPE), poly(ethylene- co -vinyl acetate) (EVA), poly(ethylene- co -propylene) (EPR), and poly(ethylene- co -propylene- co -ethylidenenorbornadiene) (EPDM). However, the cure additive is inefficient for butadiene-based materials such as 1,2-polybutadiene (vinyl-BR) and cis -1,4-poly(butadiene) ( cis -BR), since macroradical trapping by AOTEMPO stunts diene-monomer oligomerization, thereby eliminating multiple crosslinks that cannot be restored by a single polymer-bound acrylate group. Additional crosslink yield losses arise from allylic alkoxyamine instability, the details of which are revealed by independent 1 H NMR and rheology studies.