Advanced Materials: TechConnect Briefs 2015Advanced Materials TechConnect Briefs 2015

Nanocomposite Materials Chapter 6

Non-conductive ferromagnets based on core double-shell nanocomposites for radio-electric applications

H. Takacs, B. Viala, V. Hermán, J.-H. Tortai, F. Duclairoir, J. Alarcon Ramos, P.-H. Jouneau, H. Okuno and G. Tallec
CEA, France

pp. 364 - 367

Keywords: nanocomposites, nanoparticles, magnetic, graphene, surface functionalization

We report a novel flexible nanotechnology for consumer product engineering as a complementary approach from solid-state manufacturing techniques based on metallic nanoparticles and graphene chemistries. We describe two chemical routes for producing closely-packed disordered assemblies of cobalt/polystyrene nanocomposites for RF applications. The nanocomposites are based on core double-shell magnetic metallic nanoparticles coated with graphene densely dispersed into a polymeric matrix. The first route is based on the non-covalent grafting of a commercial pyrene-terminated polystyrene to the nanoparticles followed by the encapsulation of the functionalized nanoparticles inside a polystyrene matrix. In the second route, polystyrene is synthesized in situ by sonochemistry and covalently bonds to the nanoparticles before encapsulation. Polymer shell is of low molecular weight in order to form nanometer spacer between nanoparticles to avoid electric percolation while promoting magnetic dipolar coupling. Micron films are obtained by spin-coating on silicon wafers. We report on microstructure, homogeneity and uniformity (≤ 5%) of films as a function of nanoparticle weight fraction determined by thermal analysis (up to 600°C). Finally quasi-static magnetic and dynamic radio-electric results are shown and conclude on the achievement of highly magnetized (≥ 0.5T) films with negligible high frequency Joule loss up to 10GHz.