A number of chemical transformations have been found to undergo acceleration in confined environments when compared to the bulk. In particular, charged microdroplets produced by electrospray ionization (ESI) have been found to accelerate reactions by as much 10,000 times. Despite the growing body of literature demonstrating acceleration in charged microdroplets many questions about the mechanism of this acceleration remain. In this work, a series of experiments were performed to correlate microdroplet size, solute concentration, evaporative effects, and the presence of surfactant with observed acceleration in a model hydrazone formation reaction occurring in an ESI plume. In addition, super resolution microscopy was employed to obtain accurate microdroplet size information. It was found that decreasing droplet size and decreasing solute concentration both resulted in increases in reaction acceleration. Furthermore, addition of surfactant to the ESI solution resulted in enhanced acceleration. Microscopy data indicated that surfactants serve to reduce droplet size by lowering surface tension, resulting in a higher surface to volume ratio when compared to droplets without surfactant. This result, taken with the aforementioned droplet size and solute concentration studies, points to a surface mediated mechanism of reaction acceleration.<br/>

Reaction acceleration in charged microdroplets: Scratching the surface

2019 Fall National Meeting

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