Fabrication of Cobalt Oxide-Block Copolymer Nanostructured Hybrid Films via a Mixed Solvent System

The synthesized cobalt oxide (CoO) nanosheets embedded within a polymer matrix hold significant potential for applications in sensors, organic electronics, catalysis, organic photovoltaics, and energy storage devices. Using a facile and efficient preparation technique, we combine an organometallic cobalt(II) precursor, a polystyrene-block-polymethyl methacrylate (PS-b-PMMA) diblock copolymer (DBC), and organic solvents to ensure complete dissolution of all components without inducing precipitation or micro-phase separation in the liquid phase. Through a straightforward thermal annealing process, the cobalt salt within the DBC thin films undergoes decomposition, resulting in the formation of CoO nanosheets with a uniform and dense distribution pattern matching the morphology of the DBC. Fourier transform infrared spectroscopy (FTIR) confirms selective phase separation of the cobalt salt within the DBC, while x-ray photoelectron spectroscopy (XPS) indicates the conversion of the salt into CoO. The morphology of the CoO/DBC hybrid films is characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM), and x-ray scattering techniques. This study demonstrates a simple and effective route to prepare a well-defined arrangement of metal oxide clusters, achieving a highly confined particle self-assembly process compared to alternative solution-based methods.