(398e) Microfluidic Preparation of Janus Particles Via Non-Coflowing Stream

All creatures in nature have unique shapes, and which determines their own function. Janus particles, named after the god of gates in Roman myth, have two domains of different feature or functionality. They cover symmetric, asymmetric, dumbbell-like, snowman-like or various morphology. In this talk, we present very recent research activities in Janus particle preparation as well as a facile but robust approach for in situ synthesis of copolymer PNIPAAm-co-SPO-co-fluorophore-MBA Janus particles with a narrow size distribution by UV-directed phase separation in a PDMS-based microfluidic device. The monodisperse water-in-oil (W/O) droplets produced based on shear-force-driven break-off mechanism, are instantaneously converted to “acorn-like” Janus particles when subjected to UV irradiation in the downstream channel. The particles bear two classifiable architectures: the hollow body mainly composed of poly (MBA) shell having a smooth surface and the protruded head, is an aggregation of poly(NIPAAm-co-SPO-co-fluorophore) with relatively rough raspberry surface, and which also shows color change at variable temperature. The phase separation of poly(NIPAAm-co-SPO-co-fluorophore-MBA) to form Janus particles under the action of UV-irradiation is unidirectional and the protrusion always moves away from UV-direction. In addition, the morphology of the microparticles can be controlled by varying the MBA concentration. The Janus particles and their self-assembled structure will be discussed.