Controlled assembly of FePt nanoparticles monolayer on solid substrates.

The surface wettability is one of the most important factors to control the morphology of nanoparticle arrangement on the solid substrates. The various morphologies of FePt nanoparticles were fabricated on different substrates with different wetting surfaces by the Langmuir-Blodgett (LB) technology at large scale. A highly ordered structure and a dense arrangement of FePt nanoparticle monolayer were obtained on different substrates with contact angle up to 66°. The air pockets could be presented between the nanoparticles and solid substrate by theoretical analysis, because FePt nanoparticles had hydrophobic surface. A net structure of FePt nanoparticles on solid substrates could be also obtained by controlling about 45° contact angles of their surfaces. This method potentially opens up a new approach to controlling assembly of nanoparticle monolayer on solid substrates by change of the wettability on the surfaces of solid substrate and provides a promising thin film which may exhibit the excellent ultra high density magnetic recording properties.