Roughness surface of raspberry-shaped silica nanoparticles effect on shear thickening colloidal suspensions

Control over the surface roughness of silica nanoparticles can offer exciting opportunities to increase the rheological properties of the silica-based shear thickening fluids. Designing surface roughness as a significant tool indicates the possibility of connecting distinct rheological phenomena and surface chemical functionalized materials. We have experimentally synthesized two kinds of silica nanoparticles with different particle size and different functional groups at the end, which can be combined via chemical covalent coupling to generate raspberry-shaped silica nanoparticles. The dynamic viscosity of the shear thickening fluids was evaluated by rheological experiments. And the maximum impact force of puncture and drop hammer experiments were performed for composite shear thickening materials with different factors. The results showed that the essential contribution of silica nanoparticles surface roughness and covalent force illustrate that stress-activated frictional contacts can play a key role in this shear thickening phenomena. We tried to propose a damage mechanism of the shear thickening materials. The results indicate that the roughness, morphology and diameter of particles, the thickening effect of shear thickening fluids with higher volume fraction, the increase of both the number of layers and the impregnation content can significantly improve the mechanical properties of the materials.