Colloidal Synthesis of Metallodielectric Janus Matchsticks

Metallodielectric Janus particles, due to their dual composition and anisotropic properties, have found applications in catalysis, actuation, and optical applications. Their practical applications are limited by the difficulty of controlling their structures while allowing mass production. In this work, we introduce a gram-scale synthesis of matchstick-shaped metallodielectric Janus particles, which feature a gold-coated silica sphere and a straight silica rod. SiO2 Janus matchsticks are synthesized in one batch by growing amine-functionalized SiO2 spheres at the end of SiO2 rods. The amine groups on the sphere surface provide nucleation sites for the chemical deposition of a gold nanolayer that yields the Au-SiO2 Janus matchsticks. We show that the aspect ratio of the Janus matchsticks can be controlled by the length of the SiO2 rods. As both silica growth and gold coating can be performed in large reaction volumes, gram-level metallodielectric Janus matchsticks can be produced for potential use as functional colloidal materials.