Porous polymer composites and methods of preparing porous polymer composites are provided herein. In some embodiments, a method for preparing porous polymer composites may include mixing a first polymer with a solvent and a particulate filler to form a first polymer composition, wherein the amount of particulate filler in the first polymer composition is below a mechanical percolation threshold; and removing the solvent from the first polymer composition to concentrate the first polymer and particulate filler into a second polymer composition having a porous structure, wherein the particulate filler concentration in the second polymer composition is increased above the mechanical percolation threshold during solvent removal.