Fabrication of Versatile Janus Microparticles through Geometry and Surface Chemistry Control

Amphiphilic Janus particles typically comprise two distinct hemispheres with spatially dispersed physicochemical properties. The anisotropic structure and physicochemical properties of Janus particles can be exploited for various applications. However, their preparation typically requires complex and sophisticated processes and expensive equipment to control the formation of different structures and chemical compositions. Herein, a simple synthetic approach for the facile fabrication of versatile Janus particles with efficient control of the Janus ratio and wettability based on particle fixation at a three-phase interface and photopolymerization is reported. Agarose gel and surfactant are used to control the surface-coated boundaries of the Janus particles through the equilibrium of a floating microparticle at the fluid interface. poly(propylene glycol) diacrylate or poly( N -isopropylacrylamide) coating on polystyrene-based microparticles allows easy control of the chemical functionality of the particle surfaces. Depending on the particle morphology and wettability, the interfacial behavior between two immiscible liquids can be adjusted, which allows the stabilization of Pickering emulsions that encapsulate independent oil droplets in water or vice versa. This facile approach has the potential to enable more efficient mass production of Janus particles and their use in various applications, such as biomedical and environmental engineering.