Shape memory polymer actuator with graphene-ferromagnetic nanoparticle hybrid

Abstract

This paper reports a novel shape memory polymer (SMP) actuator by incorporating a graphene-ferromagnetic nanoparticle hybrid (G-Fe hybrid) to attain both the magnetic properties and enhanced physical properties of the SMP. To do that, shape memory polyurethane was selected since this polymer is a well-known biocompatible material. The G-Fe hybrid was synthesized by microwave irradiation, and the magnetic-responsive shape memory polymer was fabricated by incorporating the G-Fe hybrid into a thermo-responsive polyurethane (SMP-G-Fe) composite by solution casting. Because the magnetic nanoparticles were uniformly decorated on the surface of the graphene flakes, the loading amount of magnetic nanoparticles could be effectively adjusted by changing the initial feeding weight ratio of the metal precursor to the reduced graphene oxide (RGO). The G-Fe hybrid was homogeneously distributed in the shape memory polyurethane matrix. The Young’s modulus and thermal conductivity of the polyurethane containing the G-Fe hybrid were higher than those of the polyurethane containing magnetite ($Fe_3O_4$). Lastly, the SMP-G-Fe composite was actuated by applying an alternating magnetic field, and it showed an improved shape memory effect as compared with SMP mixed with the same amount of $RGO/Fe_3O_4$. The proposed novel shape memory polymer actuator has many possible uses in the biomedical field, such as for medical stents.