Electrorheological properties of carbon nanotubes-coated monodisperse polymeric microspheres

Monodisperse polymeric microspheres coated by single- and multi-wall carbon nanotubes were prepared and applied to electrorheological (ER) fluids. First, functionalized carbon nanotubes (fCNTs) were prepared by the chemical oxidation method. Then, the polymeric particles were functionalized by incorporating glycidyl methacrylate. Epoxy rings on the particles surface were modified to amine groups by reacting them with 3-aminopropyl trimethoxysilane. Finally, particles with attached fCNTs were prepared by covalent bonding between carboxylic acid groups on the fCNTs and amine groups on the particles. The polymeric microspheres with attached fCNTs were characterized by scanning electron microscopy, infrared spectroscopy, optical microscopy and thermal analysis. The ER properties of the fCNTs-modified microspheres were measured under controlled electric fields. The ER properties of different fCNTs (single-wall versus multi-wall carbon nanotubes) were compared. Although the amount of fCNTs anchored on the surfaces of the microspheres was less than 3 wt% of polymeric polymers, good ER properties were obtained for the fCNTs-coated particles.