Abstract:
Herein, we report a novel nanosilica-based shear-thickening fluid, whose shear-thickening performance
has been largely augmented by surface functionalizing silica employing silane chains. The functionalized
shear-thickening colloids were transparent; this suggested that they have promise for application.
An enhancement in viscosity was observed by over an order of magnitude by the usage of functionalized
particles, which could be explained on the basis of enhanced hydroclustering and an order-to-disorder
transition of the particles due to physical bonding of the silane with the base polymer. It was also
observed that the shear-thickening behavior was grossly modified due to the presence of the
functionalized nanoparticles. Oscillatory analysis showed that the functionalized colloids exhibited an
improved dynamic response, with enhanced elastic behavior under variant strain and frequency
conditions. Additionally, impact resistance tests revealed that the thickening of the viscosity upon impact
was augmented by over an order of magnitude; this established these functionalized colloids as
excellent candidates for liquid armors. The viscoelastic behavior was modeled based on the Cox–Merz
formalism. Additionally, three-element viscoelastic modeling was performed, and it was observed that
while the silica-based colloids conformed to the predominantly viscous model, the functionalized
system transited to a predominantly elastic model. The present article can have important implications
for the design and engineering of shear-thickening fluids employing nanomaterials.
