Polysaccharide-dependent depletion strategy to fabricate pickering emulsion gels

Understanding the associations between polysaccharide depletion and emulsion gelation is of great importance for achieving stable Pickering emulsion gels, but there is inconsistency in the relevant studies. In this work, we report a versatile strategy, by using depletion attractions of anionic polysaccharides - hyaluronic acid and sodium alginate, to realize the gelation of Pickering emulsions stabilized with various particles of different characteristics. The depletion interactions imposed by different ratios of a polysaccharide were demonstrated to be conducive to the formation of emulsion gels. With a higher addition of polysaccharides, emulsions underwent (1) enhanced interfacial adsorption at weak depletion, (2) bridging flocculation at moderate depletion, and (3) depletion flocculation at high depletion, which all led to the arrested dynamics and gelation of Pickering emulsions. The prepared emulsion gels exhibited good stabilities and favorable rheological properties including high gel strength, shear sensitivity, and thermostability. The universality of this study was further confirmed by using different types of Pickering stabilizers as well as oil phases. The polysaccharide-dependent depletion provides a simple strategy to design Pickering emulsion gels with tunable rheological behaviors for varied purposes.