Highly magnetic sensitivity of polymer nanocomposite hydrogels based on magnetic nanoparticles

A new polymer nanocomposite hydrogels (polymer NC gels) consisted of triblock copolymers and Fe₃O₄ nanoparticles were synthesized by the in-situ polymerization method. The polymer NC gels showed good mechanical properties and high sensitivity to magnetic field. The tensile and compression strength of polymer NC gel with low content of 1.0 wt% was about 64.0 KPa and 3.1 MPa, respectively. Moreover, the relative sensitivity (8.1 kPa/mT), high absolute (ca. 4.87 MPa), and relative magnetorheological effect (6600%) of the polymer NC gels with low content of 1.0 wt% were also observed, respectively. These results were attributed to unique multiple hierarchical structure of polymer NC gel, which was composed of cross-linking polymer network and micro magnetic fluid unit. The character provided its magnetic sensitivity of magnetorheological fluids and rubber-like elasticity of magnetorheological elastomers, together. The work did not only synthesize a new polymer gels with good mechanical properties, but also provided a universal route for the rational design of magnetorheological materials with high magnetic sensitivity for various applications.