pH-switchable pickering emulsions stabilized by polyelectrolyte-biosurfactant complex coacervate colloids

Polyelectrolyte-surfactant complexes (PESCs) have long been employed as oil-in-water (o/w) emulsions stabilizers, but never in the structure of colloidal complex coacervates providing a Pickering effect. The complexed state PESCs could make them unsuitable o/w emulsifiers, which instead require balance between and stability, amphiphilicity wettability. Here we hypothesize that are efficient stabilizers. Instead classical surfactants, employ sophorolipid (SL) biosurfactants, atypical anionic/neutral stimuli-responsive biosurfactants. Despite their tunable charge mild amphiphilic character, they can be used combination with cationic/neutral polyelectrolytes (chitosan, CHL, or poly-l-lysine, PLL) to form PESC for development biobased, also pH-switchable, emulsions. Aqueous solutions SL-CHL (or SL-PLL) emulsified dodecane. Confocal laser scanning microscopy (CLSM) electron under cryogenic conditions (cryo-SEM) demonstrate effect, while optical oscillatory rheology respectively assess emulsion formation relative viscoelastic properties. Both SL-PLL stabilize up ?oil 0.7 only pH region coacervation (6 < 9): outside this range, phase separation occurs. Rheology shows typical solid-like response mechanical recovery upon applying large deformations. CLSM cryo-SEM highlight structure, associated coacervates, oil/water interface suggest These findings effect from possibility use biobased biocompatible components, application potential cosmetics, food science, oil recovery.