Enhanced dispersion stability of shear thickening fluid based on PS@ZIF-8 core‒shell nanospheres and ionic liquids for functional applications

Material failure caused by load impacts frequently results in significant economic losses and negative effects. The application expansion of shear thickening fluid (STF) under special impact conditions is expected to lead to the design of a prospective impact-resistant structure because of its shear thickening effect, with an instantaneous response and reversible viscosity change. Herein, core–shell nanospheres (PS@ZIF-8) were synthesized using polystyrene (PS) nanoparticles as the base template. PS@ZIF-8 was used as the unique dispersed phase and was introduced uniformly into hydroxyl-functionalized ionic liquids (ILs) via simple ball mill dispersion to obtain novel STF systems. The performance of novel STF systems, such as the critical shear viscosity and peak viscosity, could be enhanced with increasing PS@ZIF-8 content. Importantly, the STF systems retained a significant shear thickening effect even after several shear scanning cycles because of the interaction between the dispersed phase (PS@ZIF-8) and the dispersion medium (ILs). The structural stability of PS@ZIF-8 in ionic liquids was also investigated, and the STF suspensions exhibited excellent stability in quantitative comparison experiments after centrifugal disruption at 8,000 r/min and standing for 60 days. In addition, a loading impact experimental method was developed to better investigate the anti-impact-wear performance of STF systems filled with limited space. The results of the tests revealed that the novel STF systems had outstanding flexibility in terms of energy absorption capacity and impact wear resistance. This study provides a strategy to prevent material failure under load impact and highlights the potential of these novel STF systems for designing efficient and stable impact-resistant structures.