Here we describe a facile yet effective
route for the fabrication
of crystal-like polymer microdiscs with a huge bump at the surrounding
edge through hydrodynamic instabilities of emulsion droplets containing
hydrophobic polymer and cosurfactant <i>n</i>-octadecanol
(OD). This strategy allows for the generation of polymer particles
with tunable size and shape by tuning the cosurfactant concentration,
emulsion droplet size, and/or solvent evaporation rate. The generation
of polystyrene (PS) microdiscs is balanced by the interfacial instabilities
of emulsion droplets, crystallization of OD, and capillary flow. Our
approach can be extended to different hydrophobic polymers and allows
for the functionalization of the discs with tunable chemical/physical
properties by incorporating functional species. By introducing magnetic
nanoparticles, we have been able to manipulate the spatial orientation
of the magnetic microdiscs via an external magnetic field. We anticipate
this simple and versatile route to be useful for the design and fabrication
of well-defined microparticles for potential applications in the fields
of targeting, separation, sensing, drug delivery, and formation of
advanced materials
