Interfacial Transport Control of Chiral Symmetry Breaking in Confined Sodium Chlorate Droplets

Chiral symmetry breaking (CSB) in crystallization is commonly achieved through strong mechanical perturbations or temperature cycles, whereas the role of interfacial transport remains less understood. Here, we investigate CSB during antisolvent crystallization of aqueous sodium chlorate droplets confined in a dodecane/ethanol/Span 80 system, using surfactant concentration to regulate interfacial transport. Increasing Span 80 concentration progressively delays observable crystallization onset, consistent with slower supersaturation development within the droplet. Crystal growth exhibits a transition from a faster early-stage regime to a slower late-stage regime, consistent with depletion of the finite solute reservoir and the resulting competition between nucleation and growth. These kinetic effects translate directly into chiral outcomes, increasing the critical droplet volume for exclusively single-handed crystallization. Interfacial-tension measurements and molecular dynamics simulations reveal a close correspondence between the critical droplet volume and interfacial surfactant coverage. Together, the results support a mechanistic framework in which surfactant-controlled interfacial transport governs supersaturation development and thereby determines CSB outcomes through nucleation−growth competition. This work establishes interfacial transport as a key factor controlling CSB in confined antisolvent crystallization systems.