(406e) Formation of Multi-Nanoemulsions for Colloidal Synthesis

Authors: 
Zhang, M., University of California, Santa Barbara
Malo de Molina, P., University of California, Santa Barbara
Helgeson, M. E., University of California, Santa Barbara
Mitragotri, S., University of California
In recent years, complex emulsions â?? i.e., droplets with internal structure â?? have generated great research interest due to their potential applications in materials,foods,cosmetics, pharmaceuticals,and chemical separations. Microfluidic methods have already demonstrated the ability to create micron- and larger scale complex emulsions with breathtaking sophistication and control, as well as compartmentalize encapsulation of molecules within them. However, scaling the size of such droplets to the nanoscale has been extremely challenging due to limitations on the devices and energies required to produce nanoscale droplets, i.e. nanoemulsions. Here, we report the ability to fabricate complex water-in-oil nanoemulsions of various morphologies, and use them as templates for forming complex structured nanoparticles. To produce complex morphologies, we combine high-energy emulsification methods with co-surfactant pairs possessing highly asymmetric molecular geometry. The former aids the generation of nanoscale droplets, and the latter influences their morphology through frustrated interfacial curvature, resulting in the reproducible generation of nanoscale core-shell and multi-core shell morphologies. The size, stability, internal morphology and chemical compartmentalization of these complex nanoemulsions have been quantified using a combination of scattering, optical microscopy and cryogenic-transmission electron microscopy techniques. We show that complex droplet morphologies are retained upon the addition of various material pre-cursors, and that the droplets are stable over the time scales required for material chemistry, thereby enabling their use as templates for complex nanoparticles. By devising and understanding new processes to make complex nanoemulsions, and particles within them, we hope to demonstrate their use as a powerful and facile tool for generating unique nanostructures with many potential applications in nanotechnology.
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