Effect of charge on the stabilization of water-in-water emulsions by thermosensitive bis-hydrophilic microgels

Hypothesis: Molecular surfactants are not able to stabilize water-in-water (W/W) emulsions, unlike nano or micro-particles, which can achieve this in some cases. However, the effect of electrostatic interactions between particles on the emulsion stability has rarely been investigated. We hypothesize that introducing charges mod-ifies the stabilization capacity of particles and renders it both pH-and ionic strength-dependent. Experiments: Charge was introduced into bis-hydrophilic and thermoresponsive dextran/polyN-iso-propylacrylamide microgels by replacing a small fraction of polyN-isopropylacrylamide with acrylic acid groups. The size of the microgels was obtained by dynamic light scattering. The stability and microstructure of dextran/ poly(ethyleneoxide)-based W/W emulsions, was studied as a function of pH, NaCl concentration and temperature using confocal microscopy and by analytical centrifugation.