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Non-spherical, highly uniform polystyrene particles as colloidal building blocks
The Lee Lab has expanded on previous research on Janus particles to develop a method for synthesizing non-spherical particles with uniform shape using seeded emulsion polymerization. Linear polystyrene particles are used as a seed for emulsion polymerization of a linear sacrificial polymer that is removed through acid hydrolysis to generate non-spherical polystyrene particles. Polymerization occurs upon placing the emulsion in an oil bath. The organic phase is removed to yield intermediate Janus particles, where one side is polystyrene and the other side is the sacrificial polymer that is subsequently removed.
Particle shape is determined by interfacial tension among the three phases of polystyrene, sacrificial polymer, and surfactant. Biconvex, plato-convex and concavo-convex particles can be produced by selecting different sacrificial polymers and surfactants, as well as by adjusting the polymer volume ratio.