Structure and magnetic properties of polymer microspheres filled with magnetite nanoparticles

The structure and magnetic properties of collagen microspheres tilled with magnetite nanoparticles arc studied. The average interparticle separation in the polymer matrix and the size of magnetite nanoparticles before and after the introduction of the nanoparticles into the matrix are determined using electron microscopy. The magnetization curve of the microspheres has a superparamagnetic character. The magnetite nanoparticles undergo no aggregation during the synthesis of microspheres and are event distributed over the matrix. The magnetic susceptibility data for magnetic polyiner microspheres ot'different diameters suggest that, at small diameters ( < 300 mum), all ofthe nanoparticics, aligned in chains, contribute to magnetization; at large diameters, some of the chains give way to clusters, the chains are shorter, and, accordingly, the susceptibility is lower.