  Porous materials are relevant for a broad range of technologies from
catalysis and filtration, to tissue engineering and lightweight structures.
Controlling the porosity of these materials over multiple length scales often
leads to enticing new functionalities and higher efficiency but has been
limited by manufacturing challenges and the poor understanding of the
properties of hierarchical structures. Here, we report an experimental platform
for the design and manufacturing of hierarchical porous materials via the
stereolithographic printing of stable photo-curable Pickering emulsions. In the
printing process, the micron-sized droplets of the emulsified resins work as
soft templates for the incorporation of microscale porosity within sequentially
photo-polymerized layers. The light patterns used to polymerize each layer on
the building stage further generate controlled pores with bespoke
three-dimensional geometries at the millimetre scale. Using this combined
fabrication approach, we create architectured lattices with mechanical
properties tuneable over several orders of magnitude and large complex-shaped
inorganic objects with unprecedented porous designs.
