High-performance shear thickening of polystyrene particles with poly(HEMA)

Abstract

Spherical polystyrene particles with poly(2-hydroxyethyl methacrylate) shells (PSt-PHEMA particles) were developed as a shear thickening fluid additive. The influence of PSt-PHEMA particle structure on the rheological properties of the shear thickening fluid was investigated. To determine the monomer ratio yielding the most effective shear thickening behavior, PSt-PHEMA particles with different ratios of styrene(St) and 2-hydroxyethyl methacrylate(HEMA) were synthesized using surfactant-free emulsion polymerization followed by dispersion into ethylene glycol to form a shear thickening fluid. The colloidal suspension containing PSt-PHEMA particles made with 4/1 ([St]/[HEMA]) exhibited the strongest shear thickening effect, with a maximum viscosity of 2800 Pa s. Our results suggest that hydroxyl groups and charged groups on the particle surface can strongly influence the rheological behavior of a particle-based shear thickening fluid.