Periodic nanocomposites: A simple path for the preferential self-assembly of nanoparticles in block-copolymers

The use of diblock copolymers as chemical templates for the self-assembly of patterned and periodic materials has been the focus of extensive research in recent years. In this current work we show how a “one-pot” solution synthesis, which is based solely on the differences in the chemical reactivity of the two blocks towards metallic moiety, can be extended to create 1-, 2- and 3-dimensional ordered arrays of nanoparticles, conforming to the microstructure of the diblock copolymer. Chromium oxide nanoparticles (Cr₂O₃) synthesized in a poly(styrene-b-methyl methacrylate) diblock copolymer solution form, after solvent evaporation and annealing, thin films consisting of a periodic composite material. We show that the preferential incorporation of the Cr₂O₃ nanoparticles into the diblock copolymer through the direct polymer block - metal interactions does not hinder the self-assembly mechanism or the thermodynamically-driven microstructure formation of the diblock copolymer. Results show that the preferential segregation that occurred as early as the mixing stage of the reaction components was maintained throughout the annealing stage and the formation of the bulk ordered composite material.