Laplace Pressure-Enabled Radical Ring-Opening Polymerization of a Thionolactone

High Resolution Image Download MS PowerPoint Slide The reactivity of radical polymerization systems is traditionally dictated by molecular design, while physical parameters such as pressure are seldom considered tools for reaction control. Here, we demonstrate that nanoscale pressure can be deliberately harnessed as a reaction design parameter to unlock otherwise inaccessible radical ring-opening pathways. Using miniemulsion polymerization as a nanoconfined reaction platform, Laplace pressure generated within nanoscale droplets enables the ring-opening copolymerization of a thionolactone monomer previously deemed inactive, yielding degradable vinyl copolymers. This pressure-assisted reactivity is further amplified by radical compartmentalization, which suppresses bimolecular termination. Independent experiments conducted in a high-pressure bulk solution confirm that pressure alone governs the observed activation, disentangling it from interfacial or confinement effects. More broadly, this work establishes pressure-enabled chemistry as a versatile strategy for expanding the accessible reaction space of radical polymerization, providing a general pathway to degradable vinyl materials without increasing molecular complexity.