Fabrication of Nano-Sized Hybrid Janus Particles from Strawberry-Like Hierarchical Composites

Janus nanoparticles possess amphiphilic properties and thus exhibit vast applications in the field of catalysis, drug delivery, displays, and surface/interface stabilizers. Despite several successful approaches, that were developed for micro-sized Janus particle fabrication, the achievement of nano-sized Janus particles is still facing challenges due to the difficulty with nanoscale processing. Here, new options for the preparation of Janus nanoparticles are demonstrated from strawberry-like hierarchical composites with designed surface functional groups for both "satellites" and spherical "core." The "satellites" of the hierarchical composites can be freely varied, from iron oxide to silica nanoparticles. Results from transmission electron microscopy, fourier transform infrared spectroscopy, and thermal gravimetric analysis measurements clearly prove the successful production of hybrid Janus silica nanoparticles coated by polystyrene and poly(acrylic acid). This technique demonstrates the vast flexibility of the abovementioned technique in terms of size, type, and surface chemistry design of Janus nanoparticles, which thus offers an additional approach to the current synthesis library of hybrid Janus nanoparticles.