Enhancing the Electrorheological Effect of Crosslinked Poly(ionic liquid)s by Copolymerizing with Acrylonitrile

Poly(ionic liquid)s (PILs) are polyelectrolytes that can produce a strong anhydrous electrorheological (ER) effect, which overcomes the limitation of the hydrous ER effect of classic polyelectrolytes. Crosslinking PILs can further broaden the working temperature range of the ER effect of PILs by increasing or eliminating the glass transition temperature. However, the crosslinked network also easily restricts the ion movement and decreases the interfacial polarization and ER effect of PILs. In this paper, we propose a chemical way to enhance the ion movement and ER effect through the copolymerization of crosslinked PILs with polar acrylonitrile (AN). The structure of the obtained copolymers was characterized by different techniques; the dielectric properties of the copolymer particles in suspensions were analyzed by dielectric spectroscopy, and the ER effect of suspensions of copolymer particles was measured by a rheometer under electric fields. It showed that the copolymerization of crosslinked PILs with an appropriate small amount of AN could enhance the ER effect, which originates from the enhancement of the interfacial polarization rate of crosslinked PILs due to the decrease in the activation energy of ions by polar AN copolymerization.