Pickering emulsion fabricated smart polyaniline/clay composite particles and their tunable rheological response under electric field

Conducting polyaniline (PANI)/attapulgite (ATP) nanocomposite particle was fabricated via Pickering emulsion polymerization and adopted as a candidate material for a polymer/inorganic -based electrorheological (ER) fluid. Scanning electron microscope and transmission electron microscope demonstrated that the PANI were covered compactly with rod-shaped ATP. Flow, viscoelastic, and yielding characteristics of the PANI/ATP ER fluid, where the synthesized particle was dispersed evenly in silicone oil, were assessed by a rotational rheometer under applied external electric field. The PANI/ATP ER fluid was found to exhibited typical ER characteristics, and the flow curves were scaled appropriately using a modified Mason number for a qualitative description of the rheological behavior of the ER fluid. All three different yield stresses measured from different methods showed a conduction mechanism with a slope of 1.5. In addition, complex viscosity determined by both Cox-Merz rule and its modified Cox-Merz rule were compared with shear viscosity measured under a steady-shear condition. The equivalence between the shear and complex viscosities was also appeared in a strain sweep test for this ER fluid.