In Situ Characterization and Interfacial Viscoelastic Properties of Pickering Emulsions Stabilized by AIE-Active Modified Alginate and Chitosan Complexes

Pickering emulsions stabilized by polysaccharide–polysaccharide complexes are attractive in many applications. However, how interface films formed by soft particles affect the stability of Pickering emulsions has not been well explored. Herein, we designed aggregation-induced emission (AIE)-active modified alginate (Alg-AIE)/chitosan (CS) polyelectrolyte complex (Alg-AIE/CS complex) colloidal particles that are used to stabilize Pickering emulsions. To explore the relationship between the interface film structure and emulsification properties, the microstructure of emulsions was directly visualized by a combination of confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The wetting properties of Alg-AIE/CS complexes were regulated by changing the amount of CS, which further regulated the aggregation behavior of the interface. The interfacial adsorption behavior of the particles and the physical stability of the emulsions were determined by combining stability analysis and employing a quartz crystal microbalance with dissipation monitoring (QCM-D). The results showed that the addition of CS resulted in more Alg-AIE/CS complexes that could be adsorbed at the oil–water interface, forming thicker and stronger viscoelastic interface films, which improved the stability of the emulsion. Most importantly, in situ visualization technology provided a new way to understand the interfacial properties of Pickering emulsions.