Surface-engineered caterpillar-like silica nanocomposites for enhanced interparticle friction and interlock in shear thickening suspension

This study presents a novel method for fabricating surface-engineered caterpillar-like silica nanocomposites by combining rod-like nanorods with spherical nanoparticles to control aspect ratios and surface functionalization. This unique design facilitates functional assembly at the nanoscale. Additionally, we developed an innovative composite by encapsulating polyurethane elastomers within shear thickening fluid (STF)-impregnated Kevlar, significantly enhancing the flexibility and durability of the resulting STF/Kevlar/PU composite. Microstructural and chemical modifications were characterized, and detailed rheological analysis revealed a 165 % increase in viscosity and a substantial rise in storage modulus from 91.56 to 18,640 Pa, indicating improved surface morphology and roughness. These enhancements promoted stronger interparticle friction and rotational motion during flow. Impact resistance tests further demonstrated a 314 % increase in peak impact force, driven by frictional interactions between the dispersed caterpillar-like particles. The results confirmed that surface roughness and adhesive forces play a critical role in activating stress-dependent frictional contacts, a key mechanism behind the improved performance. These findings highlight the potential of these composites for mitigating penetration injuries and offer precise control over the shear-thickening transition in engineering applications, making them promising candidates for lightweight protective materials.