Engineering hybrid microgels as particulate emulsifiers for reversible Pickering emulsions

Thermo-responsive microgels are unique stabilizers for stimuli-sensitive Pickering emulsions that can be switched between the state of emulsification and demulsification by changing the temperature. However, directly temperature-triggering the phase inversion of microgel-stabilized emulsions remains a great challenge. Here, a hybrid poly(N-isopropylacrylamide)-based microgel has now been successfully fabricated with tunable wettability from hydrophilicity to hydrophobicity in a controlled manner. Engineered microgels are synthesized from an inverse emulsion stabilized with hydrophobic silica nanoparticles, and the swelling-induced feature can make the resultant microgel behave like either hydrophilic or hydrophobic colloids. Remarkably, the phase inversion of such microgel-stabilized Pickering emulsions can be in situ regulated by temperature change. Moreover, the engineered microgels were capable of stabilizing water-in-oil Pickering emulsions and encapsulation of enzymes for interfacial bio-catalysis, as well as rapid cargo release triggered by phase inversion.

Automated summary

This paper successfully fabricated a hybrid poly(N-isopropylacrylamide)-based microgel with tunable wettability from hydrophilicity to hydrophobicity through temperature regulation. By synthesizing engineered microgels in inverse emulsions stabilized with hydrophobic silica nanoparticles and utilizing swelling-induced feature, the microgel can undergo phase inversion with temperature change, stabilizing Pickering emulsions and achieving stability of water-in-oil emulsions with encapsulated enzymes.