Here we developed a novel and facile microfluidic approach to produce W–O Janus droplets with a wide operating range (Ca number and volume ratio of the two dispersed phases). We then used this approach to fabricate hydrophilic–hydrophobic anisotropic Janus particles (HHAJPs). The volume ratio of the two dispersed phases and the exposure area of a specific phase could be adjusted by controlling the surfactant concentration in the continuous phase and the volume flow ratio of the two liquids. The HHAJPs could be distributed in an ordered and stable manner on oil–water interface, indicating their potential application as interface stabilizer and phase transfer catalyst.
