Intelligent snowman-shaped pH-responsive Janus emulsifier: Preparation and emulsification properties

This study introduces a novel pH-responsive Janus emulsifier based on snowman-shaped NH 2 -PS@SiO 2 Janus nanoparticles, demonstrating exceptional interfacial activity and intelligent demulsification control. The synthesized particles achieved a significant reduction in oil-water interfacial tension by 15.08 mN/m at a 1 wt% concentration, while forming stable Pickering emulsions with average droplet sizes of 72.04 μm. The system exhibited rapid and reversible pH-responsive behavior: immediate demulsification occurred under acidic conditions (pH < 7) through amino group protonation, whereas alkaline conditions (pH > 7) maintained stability via deprotonation. Zeta potential measurements confirmed charge-switching capability across a pH range of 2–12, enabling four cycles of controlled emulsification-demulsification. The unique amphiphilic Janus architecture facilitated vertical anchoring at oil-water interfaces, substantially enhancing emulsion stability compared to homogeneous counterparts. This work establishes a versatile platform for smart emulsion systems requiring on-demand destabilization.