Magnetic gels are the new generation of “smart” composite materials. They consist of a polymer medium and nano- or micro- dimensional magnetic particles embedded within it. These composites are frequently used in magnetically controlled shock absorbers, stabilizers, safety system and mechanical stress amplifiers. They can also be used in engineering and biotechnology for the regeneration of biological tissues.
A major feature of magnetic gels is their ability to change their elastic properties under the influence of moderately strong magnetic fields, which are easily provided in laboratories. But the dependence of elastic characteristics of these materials on the external field remains a poorly studied issue. Recently, the physical nature of the dependencies was investigated by a professor of the Ural Federal University, Alexander Zubarev.
Magnetic gels are a relatively “young” type of composite multifunctional material. The first studies on their synthesis date back to the late 1980s and early 1990s. But major studies on these materials really only started ten years ago.
Depending on the area of their applications, magnetic gels are manufactured on the basis of both synthetic and biological polymers. The size of the embedded magnetic particles varies from scores of nanometers to scores of microns. One of the most interesting features of magnetic gels is their ability to change their mechanical properties by several times and even orders of magnitude under the influence of moderate magnetic fields that are easily created in laboratories and in industry.
The unique properties are based on the ability of magnetic particles to preserve the most energetically favorable mutual position in a magnetic field of a given magnitude. When the material is deformed, this arrangement is disrupted, but the particles, under the influence of magnetic interaction forces, tend to return to it. This generates an additional, and often strong, elastic reaction of the material to its deformation. The ability to control the elastic response of a magnetic gel with a magnetic field is very promising for many industrial and medical technologies.
It has been demonstrated that the magnetoelastic phenomena in magnetic gels are largely determined by the initial spatial arrangement of the particles in the carrier polymer. In the new work of Andrei Zubarev, the deformations of a polymer sample with an initial homogeneous spatial distribution of magnetizable particles were investigated.
The result achieved by Zubarev and his colleagues reveals the peculiarities of change in the mutual arrangement of particles under the influence of the field and the general deformation of the composite, the influence of these features on the elasticity coefficients of the material. The theory predicts the possibility of a radical increase of the stiffness of the composite in the external field.
In the future, scientists are going to work with materials that are synthesized in an external magnetic field. In this case, the particles, under the influence of magnetic attraction, form different structures that greatly strengthens both the elastic properties of the material and the magnetomechanical phenomena in it.
The paper on this research was presented at the conference IBEREO 2017 in Valencia, Spain.