(284i) Production of Surface-Active Polymer Janus Colloids Via Flash Nanoprecipitation

Anisotropic polymer nanocolloids such as Janus and patchy particles have generated significant interest for their unique self-assembly behavior and potential life science and optical applications. However, a scalable processing platform, able to generate kilograms of material per day, and one which is flexible enough to produce a range of nanocolloid morphologies with the same equipment is highly desirable in order to implement these materials on industrial scales. Here, we demonstrate our ability to produce such anisotropic polymer nanocolloids using Flash NanoPrecipitation (FNP) as well as their utility as Pickering emulsion stabilizers. Anisotropic nanocolloids are generated via FNP when blends of polymers in solution precipitate and phase separate upon rapid mixing with a poor solvent. By making simple modifications to the components in the inlet streams, we are able to produce anisotropic particles with different morphologies and surface functionalities. Interestingly, these nanocolloids remain stable without the use of surfactants or other stabilizing agents due to electrostatic repulsion between them. Further functionalization and modification of the nanocolloid surface can then be performed to generate hybrid polymer-inorganic Janus nanocolloids or amphiphilic Janus particles which have one hydrophobic and one hydrophilic surface domain. Such nanocolloids adsorb strongly to oil-water interfaces and can be employed to stabilize Pickering emulsions.