Electromagnetic activation of a shape memory copolymer matrix incorporating ferromagnetic nanoparticles

Modified magnetite (Fe ₃O ₄) was easily mixed in a matrix of a polynorbornene-based copolymer to realize a nanocomposite of organic polymer and inorganic metal oxide nanoparticles. The crystalline structure and the diameter of the modified Fe ₃O ₄ were evaluated with X-ray diffraction and atomic force microscopy, revealing the crystalline Fe ₃O ₄ nanoparticles in the nanometer size range with an average diameter of 55 nm, a value close to that indicated by dynamic light scattering (68 nm). The transition temperature of the composite of 51 °C was determined using differential scanning calorimetry and the thermal stability and dynamic mechanical properties of the easily formed composite were investigated using thermogravimetry and dynamic mechanical analysis. The shape memory effect was evaluated in terms of shape recovery rate and speed, while thermally and electromagnetically triggered shape memory properties were documented. The recovery time triggered by Fe ₃O ₄ is 186 s.