Preparation of monodisperse silica-polyacrylamide hybrid particles with snowman or core-shell morphologies using a microfiuidic device

Hybrid particles composed of organic and inorganic parts offer unique properties owing to their physical and chemical constitution and are desirable in different applications, such as drug delivery, cosmetics, sensors, optics, and electronics. In this study, microfluidics-based preparation of monodisperse silica-polyacrylamide (PAAM) hydrogel hybrid particles with snowman or core-shell morphologies is reported. Monodisperse droplets of sodium silicate solution (water glass) were prepared using a microfluidic device, and an aqueous solution of sodium hydrogen carbonate (NaHCO3) and acrylamide (AAM) was transferred to the droplets. The reaction between sodium silicate and NaHCO3 created separate silica-rich and AAM-rich phases, forming snowman or core-shell structures, depending on the AAM concentration. These morphologies were fixed via photopolymerization of AAM. Moreover, when dispersed into an aqueous ethanol solution, the size of the PAAM hydrogel part could be easily tuned by varying the ethanol concentration.