Exchange Kinetics of Reprocessable Vulcanization Networks Regulated by Inverse Vulcanization Copolymers

The reprocessing and recycling of vulcanized rubbers remain challenging because conventional vulcanization networks are irreversible. Here, we designed a modified sulfur crosslinker via inverse vulcanization to regulate the exchange kinetics of vulcanization networks, thereby governing the mechanical recovery behavior of reprocessed rubbers. Copolymers of sulfur and thioctic acid (CSTA), synthesized via inverse vulcanization, were employed to crosslink butadiene-styrene rubber. After vulcanization, thioctic acid (TA) introduces dynamic disulfide bonds into the conventional vulcanization networks, enabling thermally activated network rearrangement while preserving the overall crosslinked structure. Kinetic analysis revealed that increasing the TA content accelerated network exchange and significantly lowered the apparent activation energy for network rearrangements. Correspondingly, the recovery of the mechanical properties after reprocessing improved with increasing TA content. These results establish a clear correlation between vulcanization network exchange kinetics and macroscopic mechanical performance, providing a kinetic basis for the design of reprocessable vulcanization networks and offering a promising route toward recyclable high-performance rubber materials.