In situ synthesis of cobalt nanoparticles in functionalized liquid crystalline polymers

Abstract

Magnetic hybrid liquid crystal composites have been obtained by thermal decomposition of a cobalt coordination precursor in the presence of a liquid crystal polymer and functional molecules (acid or amine) interacting with the precursor. The final materials contain anisotropic and/or spherical nanoparticles depending on the reaction conditions. They are all mesomorphous and ferromagnetic at ambient temperature. The role of the macromolecular chains as stabilizers of the nanoparticles has been examined. Apart from stabilizing, the polymer chains also prevent the easy access of the functional molecules to the surface of the nanoparticles, necessary to obtain anisotropic objects. Last but not least, the ferromagnetic behavior of the nanoobjects is shown to be enhanced by the presence of the liquid crystal phase: the nano-objects easily align by application of a 3 T magnetic field.