Spontaneous Room-Temperature Polymerization of Carbon Disulfide in Water Microdroplets

Water microdroplets have emerged as extraordinary reaction vessels in which ultrahigh electric fields at the air-water interface generate reactive radicals and hydrated electrons, enabling transformations inaccessible in bulk solution. However, microdroplet-induced free-radical polymerization has remained virtually unexplored. Here we demonstrate that aqueous microdroplets induce the rapid, room-temperature polymerization of carbon disulfide (CS₂) into a poly(carbon sulfide) solid. The reaction consumes CS₂ completely without catalysts at room temperature. Comprehensive characterization reveals a highly cross-linked polymer composed of conjugated C═C and C-S networks with incorporated hydrogen. Radical quenching and online mass spectrometry experiments reveal a mechanism involving electron transfer at the droplet interface, initiating stepwise CS₂ radical polymerization pathway. Gram-scale preparation is readily achieved through through small-scale parallel reactions. This discovery establishes first microdroplet-mediated polymerization for polymer synthesis and offers a viable strategy for CS₂ pollutant valorization.