Regulating Radical Flux in Frontal Polymerization.

In this study, we investigate the temperature dependence of radical flux in frontal radical polymerization (FRaP) for the generation of linear polymers. Linear polymers derived from FRaP under ambient pressure have historically been challenging, as the kinetics of polymerization have been outcompeted by polymer flow. Here, we demonstrate that tuning the initiator activation temperature unlocks linear polymer formation, enabling solution-state polymer characterization and providing deeper insight into the fundamental thermo-kinetic processes governing frontal polymerization. Furthermore, we introduce a multi-initiator formulation that enables sequential radical generation, mitigating premature termination while affording control over the radical flux and thermal profile of the propagating front. Collectively, these results highlight initiator selection as an important parameter governing radical flux, front stability, and the thermal characteristics of FRaP systems.