Electrorheological Fluid Based on Rare Earth Inclusion Complex of β-Cyclodextrin

An electrorheological (ER) fluid was made from an insulating liquid medium containing either a semi-conductive particulate material or a semi-conductive liquid material. The rheological properties of an ER fluid could reversibly change under an external electric field with the electric field strength. In this paper, a novel semi-conductive particulate material which could be used as an ER material, a rare earth (RE) inclusion complex of β-cyclodextrin, was synthesized. The nontoxic and facile β-cyclodextrin (β-CD), as well as Y(NO3)3 and p-toluenesulfonic acid (PTA) were chosen as starting materials. The relationship between the ER effect and conductivity and dielectric property, and the influence of the relationship between these properties and frequency in an ac electric field on the ER effect of a suspension were investigated. Comparing the complex with β-CD and the inclusion compound between β-CD and PTA, the suspension of the complex, of which the values of conductivity and dielectric constant and dielectric loss tangent were the largest, had the best ER performance, and no visible current was found to flow through the ER suspension in the applied electric field of 4.2 kV·mm−1, which was advantageous in its application as an ER fluid.