Bio-Based Interpolyelectrolyte Complexes for the Stabilization of Pickering-like Emulsions

Abstract

This work studies the stabilization of Pickering-like emulsions using dispersions of interpolyelectrolyte complexes (IPECs) formed by chitosan (CS) and sodium alginate (ALG), two polymers from natural resources, as the aqueous phase and soybean oil as the oil phase. The ability of these bio-based IPECs to form stable emulsions was evaluated by varying the compositional ratio of CS to ALG (Z-ratio) and the oil volume fraction (ϕo). Turbidity, zeta potential, and dynamic light scattering measurements revealed the dependence of IPEC properties on the Z-ratio, with phase separation observed near stoichiometric ratios. Phase diagram analysis showed that stable oil-in-water (O/W) and water-in-oil (W/O) emulsions could be obtained under certain combinations of the Z-ratio and ϕo. Emulsion stability increased with higher Z-ratios due to increased interfacial activity of the complexes and reduced coalescence. Emulsions with high ϕo exhibited transitions from discrete droplets to bicontinuous interfacially jammed emulsion gels (bijels), suggesting tunable morphologies. These results highlight the potential of CHI-ALG IPECs as eco-friendly and efficient stabilizers of Pickering-like emulsions for applications in food, cosmetics and pharmaceuticals.