Stimuli-responsive polymer gels have received considerable attention due to their singular mechanical properties, which make them materials of choice for niche applications. Polymer gels comprising either physical or chemical cross-links can undergo controlled and reversible shape changes in response to an applied field. The stimulus or external field applied may include thermal, electrical, magnetic, pH, UV/visible light, ionic or metallic interactions or combinations thereof. The shape change can manifest itself in two-dimensional actuation, bending motion, or three-dimensional actuation, volume change. This reversible contraction and expansion of polymer gels as well as their mechanical properties are similar to that of biological muscles. This review will describe and critique some of the recent advances in the field of stimuli-responsive polymer gels including the design of new classes of polymeric gels, controlled actuation in response to external stimuli, and ability to tailor material properties for different applications.

Stimuli-responsive polymer gels

During the last few decades, magnetorheological (MR) elastomers have attracted a significant amount of attention for their enormous potential in engineering applications. Because they are a solid counterpart to MR fluids, MR elastomers exhibit a unique field-dependent material property when exposed to a magnetic field, and they overcome major issues faced in magnetorheological fluids, e.g. the deposition of iron particles, sealing problems and environmental contamination. Such advantages offer great potential for designing intelligent devices to be used in various engineering fields, especially in fields that involve vibration reduction and isolation. This paper presents a state of the art review on the recent progress of MR elastomer technology, with special emphasis on the research and development of MR elastomer devices and their applications. To keep the integrity of the knowledge, this review includes a brief introduction of MR elastomer materials and follows with a discussion of critical issues involved in designing magnetorheological elastomer devices, i.e. operation modes, coil placements and principle fundamentals. A comprehensive review has been presented on the research and development of MR elastomer devices, including vibration absorbers, vibration isolators, base isolators, sensing devices, and so on. A summary of the research on the modeling mechanical behavior for both the material and the devices is presented. Finally, the challenges and the potential facing magnetorheological elastomer technology are discussed, and suggestions have been made based on the authors’ knowledge and experience.

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A state-of-the-art review on magnetorheological elastomer devices

The combination of polymers with nano- or microsized solid materials displays novel and often enhancedproperties compared to the traditional materials. They can open up possibilities for new technologicalapplications. Materials whose physical properties can be varied by application of magnetic fields belongto a specific class of smart materials. The broad family of magnetic field-controllable soft materialsincludes ferrofluids, magneto-rheological fluids, magnetic gels, and magnetic elastomers. The magneticgels and elastomers (magnetoelasts) represent a new type of composite and consist of small magneticparticles, usually in the nanometer to micron range, dispersed in a highly elastic polymeric matrix.The magnetic particles can be incorporated into the elastic body either randomly or in ordered structure.If a uniform magnetic field is applied to the reactive mixture during the cross-linking process, particlechains form and become locked into the elastomer. The resulting composites exhibit anisotropic properties.

Magnetic Field-Responsive Smart Polymer Composites

Magnetic field sensitive functional elastomers with tuneable elastic modulus

Effect of a homogeneous magnetic field on the viscoelastic behavior of magnetic elastomers

Magnetorheological elastomer (MRE) is a new class of smart materials, whose modulus can be controlled by the applied magnetic field. In this paper, using a white light speckle technique for deformation analysis, we present the real-time dynamic deformation progress (the vector diagram of the displacement or the whole-field quantitative displacement distribution) of the MRE and the elastomer?ferromagnet composite (EFC) while the magnetic field is turned on. The experimental results verify the prediction presented in a recently published paper, (Borcea and Bruno 2001 J.?Mech.?Phys.?Solids 49 2877?919), and reveals some interesting phenomena which will give us a deeper understanding for such smart materials.

https://iopscience.iop.org/article/10.1088/0964-1726/13/2/009/pdf

Deformation in magnetorheological elastomer and elastomer?ferromagnet composite driven by a magnetic field

This paper presents an experiment testing the accelerations of a system composed of a magnetorheological elastomer (MRE) and a cuprous mass under displacement excitation. The goal of this paper is to explain the experiment and to present the experimental results (the hysteresis loops). The method of extracting field-dependent material properties of the MRE from the results and further analysis will be presented in a subsequent paper. The experimental results reveal that the mechanical behavior is nonlinear and the field-dependent behavior of the MRE is associated with the applied frequency. (The frequency domain is divided into three ranges according to the field-dependent characteristics of the MRE.) In the low frequency range, the mechanical properties of the MRE change slightly with the applied magnetic field; in the moderate frequency range, the field-dependent properties appear and they are highly nonlinear; in the high frequency range, the field-dependent properties deviate from those of the moderate frequency range, which causes the circled area of the hysteresis loops in the two measured acceleration domains to decrease with the applied magnetic field. To explain the characteristics in the low frequency range, ABAQUS code is used to calculate the zero-field property of the MRE and a point-dipole model is employed to model the field-dependent property approximately.

G Y Zhou

Papers

Deformation in magnetorheological elastomer and elastomer?ferromagnet composite driven by a magnetic field

Dynamic behavior of a magnetorheological elastomer under uniaxial deformation: I. Experiment