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Recent research of using poly(ionic liquid) (PIL) particles as the dispersal phase has provided a new strategy to develop a high-performance anhydrous polyelectrolyte-based electrorheological (ER) fluid. However, the working temperature range of the ER fluid of PIL particles is still narrow due to an inherently low glass transfer temperature caused by the plasticization of polyatomic organic counter ions in PILs. In this paper, we develop a new ER system based on cross-linked PIL (C-PIL) particles and demonstrate that crosslinking with a suitable degree only slightly degrades the ER properties but significantly improves the working temperature range of the ER fluid of PIL particles. By using differential scanning calorimetry, rheology, and dielectric spectroscopy, we systematically study the ER properties of C-PILs and their temperature dependence at different crosslinking levels and understand the mechanism behind the improved temperature effect. The results indicate that crosslinking can effectively increase the glass transition temperature of PIL particles and enhance local ion-motion induced interfacial polarization by suppressing the thermally promoted long-range drift of mobile counter ions in the PIL matrix, and this results in the improved temperature effect of the ER fluid of C-PIL particles.

Graphene has attracted scientific interest as a substrate or additive for developing highperformance stimuli-responsive materials. Research on graphene-based polymer dielectric composites has shown an enhanced electroresponsive electrorheological (ER) effect. However, the mechanism behind the enhanced electroresponse is still incompletely understood. Here, an investigation was performed into dielectric polarization and the ER effect of reduced graphene oxide-supported polyaniline nanoplates by comparing them with pure granular polyaniline and graphene oxide-supported polyaniline nanoplates based on dielectric spectroscopy and rheologic analysis. We discovered that both anisotropic morphology and electrical properties have dominant roles in the enhanced ER effect of reduced graphene oxide-supported polyaniline nanoplates, whereas only anisotropic morphology has a dominant role in the enhanced ER effect of graphene oxide-supported polyaniline nanoplates. The analysis also showed that reduced graphene oxide-supported polyaniline nanoplates have a good ER response to both DC and AC electric field actions in the wide shear rate region. This is highly desirable for practical engineering applications. Therefore, the analysis reveals the reason for the enhanced ER effect of reduced graphene oxide-supported polyaniline nanoplates and also may provide a guide for designing high-performance ER materials for practical engineering applications by combining the advantages of conducting a reduced graphene oxide core and ER active shell.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Due to their unique anisotropic morphology and properties, graphene-based materials have received extensive attention in the field of smart materials. Recent studies show that graphene-based materials have potential application as a dispersed phase to develop high-performance electrorheological (ER) fluids, a kind of smart suspension whose viscosity and viscoelastic properties can be adjusted by external electric fields. However, pure graphene is not suitable for use as the dispersed phase of ER fluids due to the electric short circuit caused by its high electrical conductivity under electric fields. However, graphene oxide (GO) and graphene-based composites are suitable for use as the dispersed phase of ER fluids and show significantly enhanced property. In this review, we look critically at the latest developments of ER fluids based on GO and graphene-based composites, including their preparation, electrically tunable ER property, and dispersed stability. The mechanism behind enhanced ER property is discussed according to dielectric spectrum analysis. Finally, we also propose the remaining challenges and possible developments for the future outlook in this field.

This letter presents a novel, simple approach for direct electrochemical fabrication of metallic (Au or Pt) nanopillar array on gold electrode surface, employing cysteamine as a molecular anchor and anodic aluminum oxide as template without any sputtered metal as electrical conductor. The nanopillar arrays were grew directly on the electrode surface, and the prepared nanopillar array electrodes were used directly and easily to the electrochemical application.