Clean Block Copolymer Microparticles from Supercritical CO2: Universal Templates for the Facile and Scalable Fabrication of Hierarchical Mesostructured Metal Oxides

Metal oxide microparticles with well-defined internal mesostructures are promising materials for a variety of different applications, but practical routes to such materials that allow the constituent structural length scales to be precisely tuned have thus far been difficult to realize. Herein, we describe a novel platform methodology that utilizes self-assembled block copolymer (BCP) microparticles synthesized by dispersion polymerization in supercritical CO2 (scCO2) as universal structure directing agents for both hydrolytic and nonhydrolytic sol–gel routes to metal oxides. Spherically structured poly(methyl methacrylate-block-4-vinylpyridine) (PMMA-b-P4VP) BCP microparticles are translated into a series of the corresponding organic/inorganic composites and pure inorganic derivatives with a high degree of fidelity for the metal oxides TiO2 and LiFePO4. The final products are comprised of particles close to 1 μm in size with a highly ordered internal morphology of interconnected spheres between 20–40 nm ...