Temperature effect on the magneto-rheological behavior of magnetite particles dispersed in an ionic liquid

Cross-Linking and Evaluation of the Thermo-Mechanical Behavior of Epoxy Based Poly(ionic Liquid) Thermosets

Poly(ionic liquids) (PILs) and ionenes are polymers containing ionic groups in their repeating units. The unique properties of these polymers render them as interesting candidates for a variety of applications, such as gas separation membranes and polyelectrolytes. Due to the vast number of possible structures, numerous synthesis protocols to produce monomers with different functional groups for task-specific PILs are reported in literature. A difunctional epoxy-IL resin was synthesized and cured with multifunctional amine and anhydride hardeners and the thermal and thermomechanical properties of the networks were assessed via differential scanning calorimetry and dynamic mechanical analysis. By the selection of suitable hardeners, the glass transition onset temperature (Tg,onset) of the resulting networks was varied between 18 °C and 99 °C. Copolymerization of epoxy-IL with diglycidyl ether of bisphenol A (DGEBA) led to a further increase of the Tg,onset. The results demonstrate the potential of epoxy chemistry for tailorable PIL networks, where the hardener takes the place of the ligands without requiring an additional synthesis step and can be chosen from a broad range of commercially available compounds.

Nano-MRF: A Material for Damping Application

A magnetorheological fluid (MR), a suspension of micron-sized magnetic particles in a carrier fluid, has vast applications in the field of vibration dampers, seismic vibration dampers, shock absorbers, clutches, break system, vehicle suspensions, seat suspensions, Robotics, design of buildings and bridges etc. The biggest issue in MR fluid is the settling of particles under gravity. To overcome this, one of the approaches is to mix micron size particles in a magnetic fluid (MF) known as Nano-MRF. In the present paper, we report a technique to synthesis Nano-MRF suspension having high stability under gravitation as well as magnetic field. X-ray diffraction (XRD) and dynamic light scattering are used to characterize the solid/liquid system. Magnetic and Magnetorheological properties are studied and results indicate that: instead of decreasing stress with increasing temperature we have observed an increase until 40°C and thereafter, it decreases. This is explained based on, inter and intra particles/chain interaction as well as synergetic effect between small and large sized magnetic dispersion.

New frontiers in materials science opened by ionic liquids

Ionic liquids (ILs) including ambient-temperature molten salts, which exist in the liquid state even at room temperature, have a long research history. However, their applications were once limited because ILs were considered as highly moisture-sensitive solvents that should be handled in a glove box. After the first synthesis of moisture-stable ILs in 1992, their unique physicochemical properties became known in all scientific fields. ILs are composed solely of ions and exhibit several specific liquid-like properties, e.g., some ILs enable dissolution of insoluble bio-related materials and the use as tailor-made lubricants in industrial applications under extreme physicochemical conditions. Hybridization of ILs and other materials provides quasi-solid materials, which can be used to fabricate highly functional devices. ILs are also used as reaction media for electrochemical and chemical synthesis of nanomaterials. In addition, the negligible vapor pressure of ILs allows the fabrication of electrochemical devices that are operated under ambient conditions, and many liquid-vacuum technologies, such as X-ray photoelectron spectroscopy (XPS) analysis of liquids, electron microscopy of liquids, and sputtering and physical vapor deposition onto liquids. In this article, we review recent studies on ILs that are employed as functional advanced materials, advanced mediums for materials production, and components for preparing highly functional materials.