CO2-responsive Pickering emulsion stablized by modified silica nanoparticles: A dissipative particle dynamics simulation study

Dissipative particle dynamics (DPD) simulations were applied to investigate the effect of SiO2 nanoparticles (SNPs) modified with different tertiary amine chain length and concentration on O/W emulsion properties, the influence mechanism was also revealed from the molecular level. On this basis, the influence of the modified SNPs volume fraction in the emulsion system was studied. The results showed that with the increase number of tertiary amine chain alkyl carbon, the stability of the original emulsion system was first enhanced and then weakened while the responsiveness of the protonated emulsion system was first weakened and then slightly enhanced, the number of tertiary amine chains modified on SNPs has the same influence rule on emulsion performance, which was determined by the hydrophobicity of modified SNPs. In addition, with the increase of the modified SNPs volume fraction in the emulsion system, the stability of the emulsion is gradually enhanced. However, when the volume fraction of SiO2 exceeds 3%, the amplitude of stability enhancement decreases. The increase in the interaction energy between oil droplets in the equilibrium process is caused by emulsion fusion, which in turn is affected by SNPs. The repulsive force between oil and water is greater than that between two oil drops, which is the reason for the oil drop fusion. The presence of SNPs can reduce the repulsive force between oil and water to different degrees, thus slowing down the fusion of emulsion.