Selective growth of magnetic nanoparticles in domains of block copolymer films, and in polyelectrolyte multilayers

Abstract

Nonagglomerated cobalt, iron, iron-cobalt, and cobalt-nickel alloy nanoparticles, some of which exhibit significant room-temperature magnetic coercivity, have been produced by thermal decomposition of organometallic complexes in a bulk film of P(S-b-2VP). The particles are patterned on the nanoscale: they reside within the P2VP domains of the block copolymer morphology. These results are made possible by the selective sequestration of organometallic complexes into these domains in amounts sufficient to nucleate and grow substantial quantities of nanoparticles, some of which are larger than the size required for ferromagnetic behavior. Nonagglomerated metallic nanoparticles have also been produced inside polyelectrolyte films by the growth of palladium nucleating sites followed by the use of an electroless plating bath. Control of particle size and spatial distribution has been demonstrated. The effect of electroless bath chemistry on particle composition has been examined.