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Spinel ferrites (iron cobalt oxide) were prepared by the microemulsion method at different temperatures and sodium dodecyl sulphate (SDS) surfactant concentrations. Subsequently, a quantity of the different samples were coated with an intrinsically conducting polymer (ICP) shell of polypyrrole. The polymer shell was synthesized by a chemical route after the ferrites particle production. By combining in a single material the electrical conductivity of ICPs and the magnetic properties of nanopowder ferrites, new multifunctional materials have been developed. Different CoFe2O4 grain size particles were obtained ranging from 3 to 30 nm, as determined by x-ray diffraction (XRD). Particles with grain size below a critical size exhibit a superparamagnetic behaviour. These superparamagnetic particles, without and with a conducting polymer shell, were analysed by transmission electron microscopy (TEM) to find the grains’ morphology and the growth evolution of the polypyrrole shell in the ferrites grains. The electrical conductivity of the nanocomposite was measured by the four points probe method, showing values of 120 ± 4 S cm−1 at ambient temperature. The behaviour of the magnetization and the coercivity with temperature, from nearly 0 K to the ambient, were measured in a vibrating sample magnetometer (VSM).

Resol-layered silicate nanocomposites were synthesized by intercalative polymerization of phenol and formaldehyde using layered clays such as an aminoacidmodified montmorillonite (MMT) and a commercial modified MMT (Cloisite 30B). The composites were prepared by a sequential process in which one of the reactives of the phenolic resin was reacted with the organosilicate and subsequently cured with triethylamine. The nanocomposites were studied by means of X-ray diffraction, atomic force microscopy, and thermogravimetric analysis. Results show a strong clay composition dependence on the intercalation state. The composite of resol with 2 wt % aminoacid-modified MMT content has the best dispersion of clay layers. Thermal stability of nanocomposites was slightly increased in comparison with the neat resol.

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