Electrostatic Co-Assembly of Iron Oxide Nanoparticles and Polymers: Towards the Generation of Highly Persistent Superparamagnetic Nanorods

We report a protocol that allowed us to fabricate nanoparticle aggregates from anionically coated 7 nm iron oxide nanocrystals and cationic-neutral block copolymers. The control of electrostatics resulted in the elaboration of spherical clusters or of highly persistent nanostructured rods, with lengths between 1 and 50 mu m (see figure). The rods were shown to be superparamagnetic.