Magnetic Field-Responsive Smart Polymer Composites

Abstract

AbstractThe 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.Combination of magnetic and elastic properties leads to a number of striking phenomena that areexhibited in response to impressed magnetic fields. The magnetic particles couple the shape and the elasticmodulus with the external magnetic field. Giant deformational effects, high elasticity, anisotropic elasticand swelling properties, and quick response to magnetic fields open new opportunities for using such materialsfor various applications. Since the magnetic fields are convenient stimuli from the point of signal control,the magnetoelasts are promising smart materials in engineering due to their real-time controllable elasticproperties.More recently, increasing interest has been devoted to exploration of multiresponsive magnetic polymers,which exhibit sensitivity to several external stimuli. Micro- and nanospheres that combine both magnetic,temperature, and pH sensitivity were also elaborated and studied. These new results provide novel possibilitiesfor preparation of more complex magnetic field-responsive materials like membranes with on/off switchingcontrol.In this article, we review recent advances in mechanical and swelling behavior of magnetic field-responsivesoft materials, including flexible polymer networks and gels.Anisotropic elastomersFerrogelsMagnetic compositesMagnetic latexesStress–strain dependenceTemporary reinforcementVibration and shock absorber