Molecular Dynamics Simulations and Experimental Studies of the Microstructure and Mechanical Properties of a Silicone Oil/Functionalized Ionic Liquid-Based Magnetorheological Fluid

Abstract

Magnetorheological (MR) fluids are smart materials that show enormous potential in vibration control, mechanical engineering, etc. However, the effects of the solid–liquid interface strength and the interaction strength between carrier liquid molecules on the mechanical properties and sedimentation stability of MR fluids have always been unresolved issues. This work presents a new type of MR fluid that has a novel carrier liquid, i.e., silicone oil (SO) mixed with a hydroxyl-functionalized ionic liquid (IL-OH). An all-atomic Fe/SO/IL-OH interface model for studying the relationship between mechanical properties and interface strength and intermolecular interactions is established. On the basis of simulation results and theoretical analyses, the mechanical properties and sedimentation stability of the SO/IL-OH-based MR fluids are thoroughly investigated by experiments. The results show that functional ionic liquids significantly improve the mechanical properties and sedimentation stability of MR fluids. These results are essentially attributed to the stronger solid–liquid interface strength, van der Waals forces, and hydrogen bonds between the silicone oil and the functional ionic liquid. The explicit results not only help elucidate the numerous phenomena involved in the research process for MR fluids at the atomic scale but also provide insightful information on the fabrication of high-performance MR fluids.

A novel coarse-grained modeling and simulation for the microstructure evolution of ferrofluids

“…Over the past few years, the experimental studies of FF have yielded fruitful achievements. The rheological properties and sedimentation stability of FF have been improved by changing particle morphology [12,13], preparing MPs with high intensity of magnetization [14][15][16], adding reinforcing phase [17][18][19], etc. As an important characteristic reflecting the rheological behavior of FF, the microstructure has also been studied by some researchers.…”

“…To make the MPs emit bright green fluorescence, their surface was modified by polyethylenimine, and then combined with Alexa 488 fluorescent probe. However, this affects the adsorption of carrier liquid molecules on the surface of MPs, and the interaction between carrier liquid and MPs has been proven to have a significant influence on the mechanical properties of the suspensions [19,23]. Therefore, it is not only difficult to observe the real-time dynamic changes of MPs under a magnetic field, but also difficult to capture the arrangement details of MPs in the chain structure of FF through experimental methods.…”