Janus nanoparticles are a subcategory of nanoparticles that interact with solution in two or more ways, because these particles have an asymmetric makeup they can be very versatile. In this study, we synthesized silica coated gold Janus nanoparticles with a variety of morphologies.  By creating more eccentric structure, we were able to synthesize 'nanotadpoles', which has gold nanospheres as cores and silica are coated on its surface with long silica tail. The gold nanoparticle was synthesized by using a modified successive seed mediated growth, in which an initial seed is created by citric acid reduction and then growth is continued with additional gold salt. With this method, the gold nanoparticle can be obtained with sizes ranging from 15 nm up to 110nm. The AuNPs were then used to synthesis the Janus nanoparticles by using a ligand competition method, in which two ligands disperse onto the AuNP and only allow for limited nucleation of silica onto the particle. After ligands exchanging, pH is adjusted to condense silica on the surface of the AuNP. The level of eccentricity and the amount of silica nucleation points can be controlled by the concentration of ligands and solvent ratio. In addition, by adjusting ligand concentration, pH, and growth time, the morphology of silica overgrowth can vary greatly. Finally, the synthesized tadpole structure is studied in the liquid crystal systems which shows an interesting non-equilibrium motion behavior.

Morphology-controlled growth of Janus nanoparticles

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