Porous polymer composites

A method of forming a porous polymer composition without the use of phase separation, a poragen or a blowing agent, comprising:

• mixing a first polymer with a first solvent that is miscible with said first polymer and a particulate filler at a first concentration to form a first polymer composition, wherein the first concentration of particulate filler in the first polymer composition is below a mechanical percolation threshold;
• removing the first solvent from the first polymer composition to concentrate the first polymer and the 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 first concentration and the mechanical percolation threshold during first solvent removal;
• wherein the first polymer is poly(styrene-b-ethylene-co-butylene-b-styrene);
• and
• further wherein removing the first solvent from the polymer composition concentrates that filler in the first polymer above the mechanical percolation threshold of the filler in the first polymer forcing fibrils to form between filler particles and the produces a porous polymer composition with an interconnected pore structure that provides mass transport through the polymer composition without the use of phase separation, a poragen or a blowing agent.