This paper addresses the impact of the particle initial wetting and the viscosity of the oil phase on the structure and rheological properties of direct (Oil/Water) and reverse (Water/Oil) Pickering emulsions. The emulsion structure was investigated via confocal microscopy and static light scattering. The flow and viscoelastic properties were probed by a stress-controlled rheometer. Partially hydrophobic silica particles have been employed at 1 and 4 wt.% to stabilize dodecane or paraffin-based emulsions at 20 vol.% of the dispersed phase. W/O emulsions were obtained when the particles were dispersed in the oily phase while O/W emulsions were prepared when the silica was introduced in the aqueous phase. We demonstrated that, although the particles adsorbed at the droplets interfaces for all the emulsions, their organization, the emulsion structure and their rheological properties depend in which phase they were previously dispersed in. We discuss these features as a function of the particle concentration and the oil viscosity.

The degradation of (micro)gels and fractal aggregates based on self-assembled amphiphilic triblock copolymers has been investigated in water by confocal microscopy and light scattering respectively. The triblock copolymer consisted of a central hydrophilic poly(acrylic acid) (pAA) block and two hydrophobic end blocks that contained an equal amount of randomly distributed n-butyl acrylate (nBA) and AA units. These latter units helped at tempering the hydrophobic end blocks resulting in the control and the fine tuning of the dynamics of the self-assembled triblock through the pH. Starting from a pH where the dynamics is frozen, the rate of breakup of the macroscopic gels, microgels and of fractal aggregates was measured after increasing the pH to different values. The mechanism of the breakup was found to be independent of the pH, but its rate increased exponentially with increasing pH. The degradation proceeded through the release of the polymers from the bulk into the surrounding aqueous phase.

In this study, we investigated how the formation and properties of Pickering emulsions (PEs) stabilized by zein/tannic acid particles (ZTAPs) are impacted by the method used to generate the particles, before or during emulsification. ZTAPs were obtained through two antisolvent precipitation methods (sequential and co-precipitation) across zein/tannic acid molar ratio (R) range of 1/0 to 1/30. Emulsions were prepared using four methods, either with pre-formed ZTAPs or by mixing zein and tannic acid immediately before or during emulsification. The results indicated that pre-forming the particles prior to emulsification is crucial for controlling droplet size and homogeneity, while the quantity of tannic acid plays a supporting role. Tannic acid is not only critical for emulsion stabilization but also imparts its antioxidant activity to the emulsions. This activity is also controlled by the molar ratio R of the particles and the preparation protocol. ZTAPs are promising plant-based stabilizers for emulsions in the food and pharmaceutical industries. These findings provide a better understanding of the importance of their method of production in controlling the characteristics (droplet size, stability, and antioxidant properties) of the emulsions they stabilize.