Fabrication of superparamagnetic cobalt nanoparticles-embedded block copolymer microcapsules

A facile synthetic route for the preparation of block copolymer microcapsules with cobalt magnetic nanoparticles (MPs) embedded in the polymer shells is reported. The preparation involved first the Co2+ reduction to produce cobalt nanocrystals (similar to 13 nm in size). This was followed by the formation of thin polymeric coatings on the surface of Co nanoparticles owing to van der Waals attractive forces between the oxygen atoms in the block copolymer and the Co atoms and the self-assembly of capsule shells simultaneously. XRD, FT-IR, FE-SEM, TEM, and TGA were used for the characterization of the obtained hollow microcapsules. The experiments show that the reaction time and copolymer concentration are the crucial factors affecting the phase of the products. The excellent dispersibility of the products in most common solvents originates from amphiphilic nature of the block copolymer. The hybrid microcapsules are superparamagnetic at room temperature under existence of MPs and could be moved and collected with an external magnetic field, which makes these products a good candidate for multifunctional directed materials in biotechnological application.