Preparation and characterization of PEG-Dex macromolecular schiff base particles and their application on the stabilization of water-in-water emulsion

In this study, polyethylene glycol (PEG) and dextran (Dex) were chemically modified to obtain amino-functionalized PEG (PEG-(NH₂)₂) and oxidized dextran (ODex). They were subsequently reacted via -NH₂ and -CHO groups to synthesize a macromolecular Schiff base particle. The structures, morphologies, and thermal properties of the macromolecular Schiff base particle were characterized using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetry analysis (TGA). The macromolecular Schiff base particle was then employed as a stabilizer to stabilize Dex/PEG water-in-water (W/W) emulsions, and the effects of stabilizer composition, concentration, and dextran oxidation degree on emulsion phase separation and microstructure were investigated. The results from the laser particle size analyzer indicate that the macromolecular Schiff base stabilizers have particle sizes ranging from 100 to 200 nm and exhibit an interpenetrating network structure, as observed in SEM images. A decrease in emulsion droplet size was observed with increasing mass ratio of PEG-(NH₂)₂ to ODex, ODex oxidation degree, and stabilizer concentration. Rheological analysis showed that the viscosity of W/W emulsions decreased with increasing shear rate. Contact angle measurements indicated that the macromolecular Schiff base stabilizers preferentially interacted with the continuous phase of PEG, thereby promoting emulsion stability.