Magnetic applications of polymer gels

In this paper we report results of both, material preparation and magnetic characterisation, on CoFe2O4 particles of nanometric size formed by in-situ precipitation within polymer gels. The size of the particles was controlle d within a very narrow volume distribution and its average value was shifte d from 2 to 10 nm. The existence of nanoparticles showing, at room temperat ure, coercive field values between 500 and 900 Oe and saturation magnetisat ions of about 500 emu/cm(3), suggest to use these systems to get magnetic r ecording media with ultra high density. Poly(vinyl alcohol)(PVA) and Polyst yrene (PS) films were prepared from this nanocomposite material. After a ma gnetic field treatment nanoparticles within the PVA films are free to rotat e in response to an applied magnetic field. This PVA based nanocomposite fi lm portends a new class of magnetic material with very little or no electri cal and magnetic loss.