Intelligent response protection of a multi-phase shear thickening fluid based on ZIF-8 modulated rheological properties for impact loading

The application of shear thickening fluids (STFs) in impact protection has attracted increasing attention as an innovative material capable of promptly perceiving and reacting to external stimuli. Herein, we synthesized the zeolitic imidazolium ester-like skeletal structure material ZIF-8 and employed it to create a new multi-phase STF. This involved incorporating ZIF-8 particles as a third dispersed phase and using a single-phase SiO2-based STF as the base liquid. The critical shear thickening rates of multi-phase STFs that contain ZIF-8 are lower, while their peak viscosities are higher. Additionally, a new method to characterize the mechanical properties of STF was established by constructing a light-load impact testing platform. The ZIF-8-based multi-phase STFs exhibit excellent energy dissipation ability, and an increased ZIF-8 content can improve the resistance to impact wear and energy absorption ability of the STFs. In particular, the impact crater volume is only 574 mu m3 (reduced by 89.76%) when the ZIF-8 content is 7.5 wt%. The mechanism study shows that the nanoparticles inside the multiphase STF are able to form a stable frictional contact network, thereby bolstering the shear thickening effect and rapid responsiveness during the impact process. This study introduces novel concepts for the design of impact protection materials.