Magnetic properties and morphology of block copolymer templated ferrimagnetic CoFe/sub 2/O/sub 4/ nanoparticles

We synthesized the block copolymer of poly(norbornene-dicarboxcylic acid) and poly(norbornene) at room temperature, using ring opening metathesis polymerization. We then templated the CoFe/sub 2/O/sub 4/ nanoparticles within the polymer matrix, utilizing the self-assembled nature of the block copolymer. We used transmission electron microscopy, superconducting quantum interference device magnetometry, and X-ray powder diffraction to investigate the morphology and magnetic properties of the nanocomposites. The nanocomposite films are ferrimagnetic at room temperature. The CoFe/sub 2/O/sub 4/ nanoparticles are spherical and have an average radius of 8.7/spl plusmn/0.4 nm. The nanoparticles are uniformly distributed within the polymer matrix with a nanoparticle density of 110/sup 9/ particles/cm/sup 2/.