Effects of water-soluble co-solvent on properties of W/O pickering emulsions

Effects of water-soluble co-solvents(WSCs)on the properties of water/oil Pickering emulsions were investigated. Pickering emulsions were prepared in the system of 1,2,4-trimethylbenzene(TMB)/ hydrophobic silica/ water with varied concentrations of WSCs(ethanol, acetic acid and glycerin). Mean droplet diameter distributions of the obtained emulsions were studied to investigate the effects of WSCs types and concentrations. The results demonstrated that mean droplet diameter distributions decreased at first and then increased with the increase of WSC concentration. Moreover, the effect of WSC concentration on the phase inversion locus was further investigated. At the same time, infrared radiation(IR)spectrometer was used to investigate the mechanism. The results showed that the WSC attaching on hydrophobic silica changed the wettability of the particles, which facilitated the formation and phase inversion of the emulsion. The hydrogen bonds between the co-solvent groups attaching on the solid particles made a great effect on the droplet size of the emulsion and strengthened the interaction among emulsifiers. Overall, proper WSC was in favor of the stability of Pickering emulsion.