Pickering Emulsion Stabilized by Metal-Phenolic Architectures: A Straightforward In Situ Assembly Strategy

Interfacial self-assembly has been a powerful driving force for fabricating functional and therapeutic carriers in emulsion systems. Herein, we reported a straightforward metal-phenolic supramolecular architecture, directly absorbed and cross-linked at the surfaces of oil drops and acted as the regulator between the oil and water interface to stabilize the emulsion systems. The results showed that the diverse interfacial properties and emulsion stability were tuned by the kinds and concentrations of polyphenols as well as the ratios of polyphenols to metal ions. Concretely, the TA-Fe³⁺ (coordinated by tannin acid and Fe³⁺)- or EGCG-Fe³⁺ (coordinated by EGCG and Fe³⁺)-based solid particles exhibited an increasing amount of interfacial adsorption with an increase in both polyphenol and metal ion concentrations or ratios of Fe³⁺ to polyphenols, and as a consequence of which, the prepared corresponding emulsions displayed enhanced emulsion stability and diverse interfacial characteristics. The rheological measurement results also exhibited that there was an increasing trend in both G' and G″, with enhanced concentrations or ratios of Fe³⁺ to polyphenols. Generally, our study not only highlighted a straightforward strategy for the directly interfacial fabrication of emulsions to improve their stability but also advanced the understanding of broadening the application scope of the metal-phenolic networks.