Synthesis of Fe3O4 nanocubes coated by spin crossover polymer (Fe3O4@SCO) shell

Abstract

The proposed research focuses on the development of a synthesis procedure to obtain nano-hybrid materials featuring magnetic properties and a core@shell structure. The core consists of magnetic nanocubes of 15 nm diameter made of iron oxide (Fe3O4). The aim is to grow on the surface of the Fe3O4 nanoparticles a shell of a [Fe(Htrz)2(trz)](BF4) polymer with spin crossover properties. On one hand, [Fe(Htrz)2(trz)](BF4) polymer exhibits, both at the micro and nanoscale, spin transition with a characteristic hysteresis behaviour centred slightly above room temperature. On the other hand, iron oxide is chosen for its ability to be externally activated by light, releasing energy in the form of heat to facilitate the polymer's spin transition. The ultimate goal of synthesizing these structures is to harness the memory effect of the spin transition polymer for application in optoelectronic devices. Various techniques are proposed for polymer coating, including rapid polymer growth on nanoparticle surfaces and a slower two-step growth method. The two-step approach appears to yield the most promising results, as it infers the polymer's formation surrounding the metal centres. High Resolution Transmission Electron Microscope images show a slight coating on the surface of Fe3O4 nanoparticles