Thermoreversible cross-linking of ethylene/propylene copolymers based on Diels–Alder chemistry: the cross-linking reaction kinetics†
Designing reversibly cross-linked polymer materials is of great importance for repeated processing. In this work, a Diels–Alder (DA) reaction between furan and maleimide was utilized to achieve thermoreversible cross-linking of ethylene/propylene rubber (EPR) by first constructing EPR with furyl pendent groups and then adding bismaleimide molecules as a cross-linking agent. The kinetics of the cross-linking reaction was detected using the rheological test, and the apparent kinetic rate coefficient (kCL) and Arrhenius activation energy (Ea, CL) of the cross-linking reaction were determined. By adjusting the furyl content of EPR and the molecular structure of the bismaleimide, the influence of the furan/maleimide ratio as well as the bismaleimide structure on the Ea, CL value was investigated, which might provide support for the efficient realization of reversible cross-linking in polymers and the repeated processing of materials via DA chemistry.