A facile one-step method to synthesize SiO2@polydopamine core–shell nanospheres for shear thickening fluid

A facile one-step method was developed to synthesize core–shell structured SiO2@polydopamine (PDA) nanospheres. During the synthesis, a PDA shell was simultaneously coated on the SiO2 nanospheres to form the core–shell nanostructure. The PDA shell thickness was tunable by varying the concentration of the starting dopamine precursor. After dispersing the core–shell nanospheres into poly(ethylene glycol) 200 (PEG200), a SiO2@PDA based shear thickening fluid (STF) was obtained. In comparison to pristine SiO2, the SiO2@PDA based STF presented better ST effects and its maximum viscosity could reach as high as 194.6 Pa s. A possible enhancement mechanism was proposed in order to investigate the structural dependence of the ST effect. This high performance SiO2@PDA based STF could be widely applied in body armor and other safe-guarding areas.