Pickering Emulsions Stabilized by Diblock Copolymer Worms Prepared via Reversible Addition-Fragmentation Chain Transfer Aqueous Dispersion Polymerization: How Does the Stimulus Sensitivity Affect the Rate of Demulsification?

Responsive Pickering emulsions exhibit promising application in industry owing to the integration of the high storage stability with on-demand demulsification. In this study, stimuli- responsive Pickering emulsions stabilized by poly[oligo(ethylene glycol) methyl ether methacrylate](15)-b-poly(diacetone acrylamide)(120) (E15D120) worms were indicated, in which E15D120 worms were prepared via reversible addition-fragmentation chain transfer-based aqueous dispersion polymerization using thermo-sensitive POEGMA(15) as both the stabilizer block and macro-chain transfer agent. The factors influencing the morphologies of copolymers during polymerization-induced self assembly have been investigated. A series of different morphological polymer nanoparticles including spheres, worms, and vesicles could be produced through rational synthesis. E15D120 worms demonstrated excellent emulsifying performances and could be used as emulsifiers to form n-dodecane-in-water Pickering emulsions at a low content. The formed n-dodecane-in-water Pickering emulsions revealed a slow demulsification at pH 10 or 70 degrees C or pH 10/70 degrees C combinations, and several hours were needed for the demulsification of Pickering emulsions. However, n-dodecane-in-water Pickering emulsions displayed a rapid demulsification (similar to 10 min) at an elevated temperature, such as 90 degrees C. The different demulsification rates were attributed to different sensitivities of E15D120 worms to external stimuli. Pickering emulsions integrating a rapid responsive demulsification with a slow one would be well satisfactory on different occasions.

Automated summary

Stimuli-responsive Pickering emulsions stabilized by E15D120 worms demonstrated excellent emulsifying performances and different demulsification rates under various external stimuli. Through rational synthesis, a series of different morphological polymer nanoparticles could be produced.