Insights into emulsion viscoelasticity correlated with particle hydrophobicity and surface charge

Pickering emulsions (PEs) stabilized by nanoparticles have shown significant potential in diverse applications. However, the complex influence of particles on PE makes it difficult to predict how particle hydrophobicity and surface charge affect viscoelastic behavior. In this work, an <i>in situ</i> hydrophobization method was employed to modify silica nanoparticles (SNPs), yielding a series of SNPs with controlled hydrophobicity and surface charge for the preparation of PEs. The findings demonstrated a significant relationship between the surface characteristics of SNPs and the viscoelasticity of PEs. Under conditions of strong electrostatic repulsion, increased hydrophobicity reduces the viscoelasticity of PEs. In contrast, when the surface charge was weak, the maximum viscoelasticity was observed at a hydrophobicity of 90°. These results clarify the mechanisms underlying PE viscoelasticity and provide valuable guidance for the rational design of tunable PEs. The established property-performance relationships offer valuable guidance for tailoring PE rheology through precise particle surface engineering.