Effect of Iron Oxide Nanocrystal Content on the Morphology and Magnetic Properties of Polystyrene-block-poly(methyl methacrylate) Diblock Copolymer Based Nanocomposites

Iron oxide nanocrystals, synthesized by surfactant-assisted thermal decomposition of Fe(CO)5, were selectively incorporated into the microseparated PS block phase of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer to design novel nanostructured inorganic/organic materials with magnetic properties. The colloidal synthesis led to oleic acid- and oleylamine- capped magnetic γ-Fe2O3 maghemite nanocrystals, which resulted well-dispersible in the block copolymer up to 60 wt % due to the affinity between PS block and organic surfactants. Atomic force and scanning electron microscopy confirmed that nanocomposites with nanocrystal loading lower than 40 wt % maintained cylindrical morphology, even without additional treatment applied to enhance their nanostructuration. Nanocrystals appeared well-dispersed in the nanocomposites at low contents, while nanocrystal clusters, with size depending on their loading, were observed at higher contents. At the highest nanocrystal content, the nanostru...