Fabrication of semiconducting polyaniline/nano-silica nanocomposite particles and their enhanced electrorheological and dielectric characteristics

The Electric Field Responses of Inorganic Ionogels and Poly(ionic liquid)s

Ionic liquids (ILs) are a class of pure ions with melting points lower than 100 °C. They are getting more and more attention because of their high thermal stability, high ionic conductivity and dielectric properties. The unique dielectric properties aroused by the ion motion of ILs makes ILs-contained inorganics or organics responsive to electric field and have great application potential in smart electrorheological (ER) fluids which can be used as the electro-mechanical interface in engineering devices. In this review, we summarized the recent work of various kinds of ILs-contained inorganic ionogels and poly(ionic liquid)s (PILs) as ER materials including their synthesis methods, ER responses and dielectric analysis. The aim of this work is to highlight the advantage of ILs in the synthesis of dielectric materials and their effects in improving ER responses of the materials in a wide temperature range. It is expected to provide valuable suggestions for the development of ILs-contained inorganics and PILs as electric field responsive materials.

The preparation and electrorheological behavior of bowl-like titanium oxide nanoparticles

Bowl-like titanium oxide nanoparticles were successfully prepared by a simple solvothermal method using absolute ethanol and isopropanol as the cosolvent. Ostwald ripening coupled with the inner-stress-induce effect were assumed to play an important role in the formation of this unique bowl-like morphology. The morphological evolution from solid nanosphere to bowl-like nanoparticle was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Besides, the structural characteristics of the as-synthesized TiO₂ nanoparticles were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and thermogravimetric analysis (TGA). Moreover, a rotational rheometer was operated to examine the electrorheological (ER) effect. Excellent ER properties were achieved when the TiO₂ particles were dispersed in silicone oil under an external electric field.

Core/shell-structured, covalently bonded TiO2/poly(3,4-ethylenedioxythiophene) dispersions and their electrorheological response: the effect of anisotropy

Higher surface area, rod-to-rod interactions and conducting thin shell induced covalently-bonded core/shell nanorod-TiO₂/PEDOT nanocomposite to show stronger ER activity and higher recovery after stress loading compared to particulate one.

From terpyridine-based assemblies to metallo-supramolecular polyelectrolytes (MEPEs)

Introducing metal ion coordination as bonding motive into polymer architectures provides new structures and properties for polymeric materials. The metal ions can be part of the backbone or of the side-chains. In the case of linear metallo-polymers the repeat unit bears at least two metal ion receptors in order to facilitate metal-ion induced self-assembly. If the binding constants are sufficiently high, macromolecular assemblies will form in a solution. Likewise, polymeric networks can be formed by metal ion induced crosslinking. The metal ion coordination sites introduce dynamic features, e.g. for self-healing or responsive materials, as well as additional functional properties including spin-crossover, electro-chromism, and reactivity. Terpyridines have attracted attention as receptors in metallo-polymers due to their favorable properties. It is well suited to assemble linear rigid-rod like metallo-polymers in case of rigid ditopic ligands. Terpyridine binds a large number of metal ions and are readily functionalized giving rise to a plethora of available ligands as components in metallo-polymers. By the judicious choice of the metal ions, the design of the ligands, the counter ions and the boundary conditions of self-assembly, the final structure and properties of the resulting metallo-polymers can be tailored at all length scales. Here, we review recent activities in the area of metallo-polymers based on terpyridines as central metal ion receptors.

Electrorheological fluids based on metallo-supramolecular polyelectrolyte-silicate composites

We present an innovative concept for the design of electrorheological fluids (ERF) based on a dispersed phase of rigid-rod-shaped metallo-supramolecular polyelectrolytes (MEPE) intercalated in mesoporous SBA-15 silica. While applying an electric field to this composite dispersed in silicone oil, rheological measurements reveal a strong increase in the storage modulus, indicating the solidification of the fluid. Besides the strong electrorheological effect and the low current densities, we note that the required amount of MEPE is five times lower than in comparable host-guest ERFs. Composites based on mononuclear complexes do not show a comparable electrorheological effect.