Crystal Templating with Mutually Miscible Solvents: A Simple Path to Hierarchical Porosity

Ice templating, a route where ice crystals are used to template macroporosity, has been used to process a variety of materials with one level of macropores. We demonstrate here a variant of ice templating based on the solidification of mutually miscible solvents. The solidification of different phases, each defined by their own size and morphology, provides a simple one-step processing route for materials with hierarchical porosity defined by up to three levels of macroporosity. These concepts are demonstrated with both ceramic (yttria-stabilized zirconia) and polymer (polyvinyl alcohol) materials.