Investigation on the effects of SiO2 nanoparticles with different surface affinity on the viscoelasticity of wormlike micelles

The effects of both hydrophilic and hydrophobic SiO 2 nanoparticles (NPs) on the viscoelasticity of stearyltrimethylammonium bromide/sodium salicylate wormlike micelles (WLMs) solutions were investigated. The micelle-nanoparticle junctions obviously increased the contour length L c of the WLMs to facilitate the viscoelasticity of WLMs solution, which could be reflected by cryo-TEM images and Maxwell model. The effects of SiO 2 NPs on the zero-shear viscosity and the flow activation energies of WLMs with different surfactant alkyl chain lengths were explored in the controlled experiments. It was found that the viscoelasticity of WLMs/NPs mixture was associated with the strength of the hydrophobic effect between the SiO 2 NPs and surfactant molecules in the micelle-nanoparticle junction. The number densities of micelle-nanoparticle junction in hydrophilic and hydrophobic SiO 2 NPs systems were calculated by the mathematical model to confirm our proposed hypothesis.