Mechanical testing and reinforcing mechanisms of a magnetic field-sensitive hydrogel prepared by microwave-assisted polymerization

A novel magnetic field-sensitive composite hydrogel was prepared by microwave-assisted polymerization of salecan and 3-acrylamidopropyl trimethylammonium chloride in the presence of Fe3O4@tannic acid (TA) nanoparticles. FT-IR spectroscopy confirmed the formation of the copolymer structure. XRD patterns clearly showed the crystal planes of Fe. TGA verified that incorporation of Fe3O4@TA nanoparticles into the copolymer matrix greatly enhanced the thermal stability of the composite hydrogel. The water uptake, retention, saturation magnetization and pore size can be well modulated by changing Fe3O4@TA content. More importantly, mechanical tests revealed that the compressive and storage moduli were significantly improved by the introduction of Fe3O4@TA nanoparticles or application of external magnetic field, probably due to the particles alignment and subsequent structural rearrangement of polymer chains under the magnetic field. The reinforcement mechanism reported here offers a universal strategy for enhancing the comprehensive mechanical properties of polysaccharide-based materials.