A dual latent catalyst for achieving a broad gelation window and creep resistance in epoxy vitrimers

The emergence of epoxy vitrimers has revolutionized epoxy thermosets by endowing them with recyclability via dynamic bond exchange, thereby promoting sustainable material lifecycles and supporting the circular economy. However, the inevitable use of catalysts in the formulation of epoxy vitrimers introduces practical processing challenges (narrowing the gelation window) and poses a critical risk of creep under service conditions. Here, we report a dual latent catalyst based on 1,5,7-triazabicyclo[4.4.0]dec-5-ene tetraphenylborate, which operates through two distinct activation thresholds with stepwise increasing activity. This dual latent catalyst is universally compatible with widely adopted epoxy formulations and enables independent and sequential control over both network curing and dynamic bond exchange reactions. Below 80 °C, TBD-TPB is inert to both curing and bond exchange, expanding the gelation window and preserving low viscosity for compatibility with standard industrial protocols. Above 90 °C, TBD-TPB selectively activates the curing reaction while suppressing bond exchange, guaranteeing effective network formation and creep resistance. Only upon heating to 210 °C, TBD-TPB undergoes structural transformation to become highly active toward bond exchange, enabling complete material recycling and reuse. This unique dual latent catalytic behavior offers a versatile strategy to advance the practical manufacturing of high-performance vitrimers or dynamic polymers.