In situ thermolysis of magnetic nanoparticles using non-hydrated iron oleate complex

A novel strategy for the fabrication of nanostructured materials based on preparation of metallic surfactants is presented and some examples are demonstrated in this article. The suggested synthetic procedure of metal oleate is universal, potentially able to produce bulk quantities, and can be applicable to the synthesis of other metal oxide and metal nanoparticles. In general, organometallic compounds are quite expensive and are mostly classified as a highly toxic substance. In this study, we used simple, inexpensive, and eco-friendly approaches to prepare the metallic surfactants. As an example, non-hydrated iron oleate (FeOl) complexes are prepared as precursors for the in situ-fabricated superparamagnetic iron oxide nanoparticles (SPIONs) by thermolysis. The different coordination of the non-hydrated FeOl complexes are directly relating to the competition between nucleation and crystal growth. The in situ preparation of SPIONs involves the reaction of metal nitrate and carboxylic acid at 120 °C to synthesize the non-hydrated FeOl complexes and following the thermolysis of FeOl at 300 °C in non-coordination solvent. The coordination modes and distinct thermal behaviors of intermediates non-hydrated FeOl complexes are comparatively investigated by means of thermo-analytic techniques complimented by differential scanning calorimetry, thermal gravimetric analysis (TGA) and infrared spectroscopy (FTIR). The potential chemical structures of non-hydrated FeOl and their reaction mechanism by thermolysis were elucidated. The resulting lipid-coated SPIONs were characterized by transmission electron microscope, FTIR, differential temperature analysis, and TGA. These data suggested a bimodal interaction of organic shell and nanoparticle surface, with chemically absorbed inner layer and physically absorbed outer layer of carboxylic acid.