Revolutionizing protective materials: Ultrahigh peak viscosity through MOF-enhanced shear thickening fluid for advanced soft body armor

The incorporation of shear thickening fluid (STF) into aramid fabric has emerged as a compelling strategy to augment the protective attributes of aramid-based soft body armor. The peak viscosity of STF assumes a pivotal role in shaping the efficacy of this enhancement. In this study, we present an innovation in the design and synthesis of an ultrahigh peak viscosity STF using metal-organic framework (MOF)/SiO 2 nanoparticles as the core constituents. The remarkable enhancement in peak viscosity of MOFs/SiO 2 -based STF, taking ZIF-8 as an exemplary MOFs material, is attributed to the pronounced interparticle contact friction facilitated by the rugged surface morphology of the ZIF-8/SiO 2 nanoparticles. Therefore, ZIF-8/SiO 2 -based STF (62.5 wt.%) demonstrates a peak viscosity approximately 3938 times greater than that of conventional SiO 2 -based STF (62.5 wt.%). This extraordinary STF formulation has been successfully employed in aramid fabric-based soft body armor, resulting in a significantly advancement in protective performance. Compared to Kevlar fabric impregnated with SiO 2 -based STF (62.5 wt.%), the utilization of ZIF-8/SiO 2 -based STF (62.5 wt.%) results in substantial and scientifically significant improvements in key mechanical parameters. These include a notable 15.4 % increase in maximum stabbing force, a remarkable 29.5 % augmentation in maximum yarn pull-out force, a 24.3 % boost in maximum yarn tensile strength, and a 204.5 % enhancement in maximum fabric tensile strength. This research underscores the profound impact of synergizing ZIF-8 and SiO 2 within the STF matrix, and significantly improves the protective abilities of SiO 2 -based STF-impregnated Kevlar fabrics, which provides a new route to design STF-impregnated ballistic fabric with high protective performance.