Surfactant-stabilized emulsions have emerged as versatile materials within which to study and design chemotactic colloidal motion, interactions, and collective behavior. Conventionally, active droplets exhibit self-propulsion and pairwise repulsion due to Marangoni flows generated by solubilization processes and/or the solubilization products raising the droplet’s interfacial tension. Here, we present emulsions with the opposite behavior, namely that solubilization and/or its products decrease the interfacial tension and cause droplets to attract and cluster. We systematically characterize the influence of oil structure, nonionic surfactant structure, and surfactant concentration on the interfacial tensions and Marangoni flows of solubilizing oil-in-waterdrops. Three regimes corresponding to droplet “attraction”, “repulsion” or “inactivity” are identified and the chemical trends leading to these behaviors are discussed. We believe these studies contribute to a new fundamental understanding of solubilization processes in emulsions and provide guidance as to how chemical parameters can be used to influence the dynamics and chemotactic interactions between active droplets.

Modulating chemotactic behaviors of solubilizing oil droplets

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.