Light‐Driven Spatiotemporal Pickering Emulsion Droplet Manipulation Enabled by Plasmonic Hybrid Microgels

Abstract

AbstractThe past decades have witnessed the development of various stimuli‐responsive materials with tailored functionalities, enabling droplet manipulation through external force fields. Among different strategies, light exhibits excellent flexibility for contactless control of droplets, particularly in three‐dimensional space. Here, we present a facile synthesis of plasmonic hybrid microgels based on the electrostatic heterocoagulation between cationic microgels and anionic Au nanoparticles. The hybrid microgels are effective stabilizers of oil‐in‐water Pickering emulsions. In addition, the laser irradiation on Au nanoparticles creats a “cascade effect” to thermally responsive microgels, which triggers a change in microgel wettability, resulting in microgel desorption and emulsion destabilization. More importantly, the localized heating generated by a focused laser induces the generation of a vapor bubble inside oil droplets, leading to the formation of a novel air‐in‐oil‐in‐water (A/O/W) emulsion. These A/O/W droplets are able to mimic natural microswimmers in an aqueous environment by tracking the motion of a laser spot, thus achieving on‐demand droplet merging and chemical communication between isolated droplets. Such proposed systems are expected to extend the applications of microgel‐stabilized Pickering emulsions for substance transport, programmed release and controlled catalytic reactions.