Electrorheological behavior of suspensions of camphorsulfonic acid (CSA) doped polyaniline nanofibers in silicone oil

Abstract

The electrorheological (ER) effect is known as the enhancement of the apparent viscosity upon application of an external electric field applied perpendicular to the flow direction. Suspensions of polarizable particles in non-conducting solvents are the most studied ER fluids. The increase in viscosity observed in the suspensions is due to the formation of columns that align with the electric field. This work presents the ER behavior of suspensions, in silicone oil, of camphorsulfonic acid (CSA) doped polyaniline (PANI) nanofibers. The ER properties of the suspensions were investigated with a rotational rheometer, to which an ER cell was coupled, in steady shear, and electrical field strengths up to 2 kV mm−1. The effects of the electric field strength, content of nanostructures and viscosity of the continuum phase, in the shear viscosity and yield stress, were investigated at room temperature. As expected, the ER effect increases with the increase of the electric field as well as with the increase of content of nanofibers and it decreases with the increase of the oil viscosity. The suspensions present giant ER effects (higher than 2 orders of magnitude increase in viscosity for low shear rates and high electric fields), showing their potential application as ER smart materials.

Recent Progress on Electroactive Polymers: Synthesis, Properties and Applications

“…Another type of ionic EAP is represented by electrorheological fluids (ERFs). ERFs most often consist of inorganic particles in suspension with a liquid, though there is also ongoing research on hybrid ERFs that include organic and inorganic materials [33]. These are defined for their ability to change viscosity in the presence of an electric field.…”

“…Due to their ability to turn electric charge into mechanical energy, applications of ERFs primarily include valves, clutches, and robotic components. For these purposes, ERFs can be fabricated into various structures [33][34][35]. Polyaniline (PANI) is advantageous for such applications since it can be added to the matrix as nanoparticles (0D), as nanowires or nanotubes (1D), as nanosheets or nanobelts or films (2D), and as a hierarchical nanostructures (3D) [36][37][38].…”

The electrorheological performance of polyaniline-based hybrid particles suspensions in silicone oil: influence of the dispersing medium viscosity

“…According to this model reported elsewhere [4], the strength of the interaction between two polarized particles in a Newtonian fluid (the origin of the yield stress) is mainly attributed to the dielectric constant mismatch between particle and medium, but is also influenced by the particle microstructure. Hence, parameters a and b are affected by all these variables [8,9,35].…”

“…Among these materials, conducting polymers have received considerable attention based on their advantages such as a wide range of working temperature, facile variation in conductivity, intrinsic polarizability, low cost and relatively low current density. In particular, polyaniline (PANI) is one of the conducting polymers most frequently used in ER fluids because it meets the above mentioned list of desirable properties [8][9][10]. Despite that, both nano/microstructured PANI hybrids have also been developed in order to improve further its limited ER performance.…”

Enhanced Electrorheological Response of Cellulose: A Double Effect of Modification by Urea-Terminated Silane

“…Polymer-based ER materials are attractive candidates as they can overcome some drawbacks of inorganics, but they have relatively lower ER effects. Chemical modification and composite methods have been applied to enhance the ER effects of polymer-based ER materials [39,40,41,42].…”