title: Interfacial Polymerization on Dynamic Complex Colloids: Creating Stabilized Janus Droplets.
abstract: Complex emulsions, including Janus droplets, are becoming increasingly important in pharmaceuticals and medical diagnostics, the fabrication of microcapsules for drug delivery, chemical sensing, E-paper display technologies, and optics. Because fluid Janus droplets are often sensitive to external perturbation, such as unexpected changes in the concentration of the surfactants or surface-active biomolecules in the environment, stabilizing their morphology is critical for many real-world applications. To endow Janus droplets with resistance to external chemical perturbations, we demonstrate a general and robust method of creating polymeric hemispherical shells via interfacial free-radical polymerization on the Janus droplets. The polymeric hemispherical shells were characterized by optical and fluorescence microscopy, scanning electron microscopy, and confocal laser scanning microscopy. By comparing phase diagrams of a regular Janus droplet and a Janus droplet with the hemispherical shell, we show that the formation of the hemispherical shell nearly doubles the range of the Janus morphology and maintains the Janus morphology upon a certain degree of external perturbation (e.g., adding hydrocarbon-water or fluorocarbon-water surfactants). We attribute the increased stability of the Janus droplets to (1) the surfactant nature of polymeric shell formed and (2) increase in interfacial tension between hydrocarbon and fluorocarbon due to polymer shell formation. This finding opens the door of utilizing these stabilized Janus droplets in a demanding environment.
authors.affiliation: Department of Chemistry and Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology , Cambridge Massachusetts 02139, United States.
authors.forename: Yuan
authors.identifier: http://orcid.org/0000-0001-8676-1203
authors.initials: Y
authors.lastname: He
authors.affiliation: Department of Chemistry and Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology , Cambridge Massachusetts 02139, United States.
authors.forename: Suchol
authors.initials: S
authors.lastname: Savagatrup
authors.affiliation: Department of Chemistry and Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology , Cambridge Massachusetts 02139, United States.|Department of Materials Science and Engineering and Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Lauren D
authors.identifier: http://orcid.org/0000-0002-3287-3602
authors.initials: LD
authors.lastname: Zarzar
authors.affiliation: Department of Chemistry and Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology , Cambridge Massachusetts 02139, United States.
authors.forename: Timothy M
authors.identifier: http://orcid.org/0000-0002-3577-0510
authors.initials: TM
authors.lastname: Swager
keywords: Janus droplets; dynamic complex colloids; interfacial polymerization; morphological stability; optical properties