Synthesis and Applications of Anisotropic Colloidal Dimers

Anisotropic particles have attracted lots of attention due to their wide applications in optical display, emulsion stabilization, biomedical imaging, and drug delivery. We have successfully synthesized colloidal dimers with properties targeting for three different applications: directed-assembly under electric fields, colloidal surfactants, and self-propelling micro-motors. Colloidal dimers with geometric anisotropy showed interesting assembly behavior, such as chiral structures and Ising-like crystals, under electric fields. Dimers with interfacial or compositional anisotropy could also be used as colloidal surfactants. Stimuli-responsiveness was also incorporated into colloidal surfactants by adding functional polymers such as poly(N-isopropylacrylamide) and poly(acrylic acid). Self-propelling motors can also be made from dimers in which one lobe is coated by platinum. These dimers exhibited both linear and circular movement in a mixture of hydrogen peroxide and water.