FePt nanocrystals embedded in methylmethacrylate polymers

A simple, controlled and reproducible procedure is reported to obtain polymerized methylmethacrylate by embedding monodisperse Fe₆₀Pt₄₀ nanoparticles. The magnetic properties of the composite material can be controlled by the magnetic properties and the concentration (up to 0.3 wt%) of the starting nanoparticle dispersions. SQUID magnetometry measurements of FePt-doped methylmethacrylate polymers show superparamagnetic behavior at room temperature confirming the homogeneous particle distribution and the non-occurrence of agglomerates inside the polymeric matrix also observed by transmission electron microscopy. Even at the highest concentration the average particle distances are so large that no particle interactions play a role.