Microfluidic Synthesis and Surface Engineering of Colloidal Nanoparticles\n

Microfluidic Synthesis and Surface Engineering of Colloidal Nanoparticles
There has been considerable research interest over the last decade in fabricating core-shell materials with tailored optical and surface properties. For example, core-shell particles of silica and titania have drawn attention due their potential for trapping light at specific frequencies. This optical property depends on the formation of nanolayers on nano- or micro-cores. To obtain useful particles, these layers need to be uniform and even. These layered particles also need to be distinct and monodispersed. While nanolayer formation is successful in batch reactions, nonuniformity, agglomeration, and secondary nucleation often occur. We have developed microfluidic routes for synthesis and surface-coating of colloidal silica and titania particles.

The chief advantages of a microfluidic platform are precise control over reactant addition and mixing and continuous operation. Microfluidic chemical reactors for the synthesis and overcoating of colloidal particles. We have studied a SEM micrograph of silica particles synthesized in a microreactor operated in segmented gas-liquid flow mode. We also show a silica nanoparticle coated with a thick shell of titania. We have fabricated integrated devices combining synthesis and overcoating to enable continuous multi-step synthesis of core-shell particles.