Impact of nanoparticles concentration on the properties of a reversible emulsion stabilized by pH-responsive cationic surfactant

An experimental investigation was conducted to evaluate the impact of silica nanoparticles concentration on a pH-responsive emulsion system in terms of its emulsification, phase inversion mechanisms and long-term stability. Also, the adsorption studies of the pH-responsive emulsifier and the nanoparticles were evaluated in order to comprehend the synergism between the nanoparticles and the emulsifier. The sorption of the emulsifier onto the surfaces of the nanoparticles caused wettability alteration enabling the nanoparticle to act as nanocomposite emulsifier. It was found out that the emulsions undergoes phase inversion upon treating it with a minimum of 1 ml of 0.5 M HCl and also increasing the nanoparticles concentration had no noticeable effect on the phase mechanism, However, the nanoparticles cannot stabilized the O/W formed after the phase inversion. The presence of the nanoparticles improves the thermal stability of the reversible emulsion and also protects the emulsions against the presence of NaBr and otherwise for salts like NaCl and Na2SO4. These outcomes reveal the various properties of a pH-responsive emulsion which are affected by the presences of nanoparticles in order to fully control stimuli-responsive emulsions to our advantage.