Superparamagnetic magnetite-polystyrene composite colloids with anisotropic structures

COLL 206

Jianping Ge, jianping@ucr.edu, Yongxing Hu, yhu002@student.ucr.edu, and Yadong Yin, yadong.yin@ucr.edu. Department of Chemistry, University of California, Riverside, 501 Big Springs Road, Riverside, CA 92521
Colloidal particles with anisotropic structures have various applications such as active components for biosensors and building blocks for photonic bandgap materials. Here we report the synthesis and assembly of superparamagnetic magnetite-polystyrene composite colloids with anisotropic structures. Magnetite colloidal particles were first synthesized using a high-temperature hydrolysis process, and then used as seeds for the subsequent emulsion polymerization process. By controlling the reaction conditions, we are able to produce magnetite-polystyrene composite colloids with various geometric shapes, including isotropic core-shell spheres, anisotropic core-shell spheres, dimers and rods. These anisotropic structures show dramatically different self-assembly behavior than isotropic structures when they are subjected to an external magnetic field, producing interesting structures such as zig-zag chains. We believe that these composite particles, with superparamagnetic property and anisotropic structures, would allow a wide range of potential applications.