Hierarchically porous polymers with controllable pore size were generated through a novel polymer blending strategy in an A/B/C-B-C ternary blend system. Polylactide/high-density polyethylene/poly(styrene-ethylene/butylene-styrene) triblock copolymer (PLA/HDPE/SEBS) was used as a model system to demonstrate this technique. During melt blending, the SEBS was driven into the HDPE phase owing to the presence of the PE block in the copolymer. With proper volume fractions of PLA/HDPE/SEBS (e.g., 50/25/25), a bi-modal, dual co-continuous morphology was obtained and hierarchically porous polymeric materials were further generated by selectively removing the PLA and SEBS phases. Annealing and compositional variation were further employed to control the pore size and it is shown that the length scales of the two co-continuous morphologies can be controlled independently. (C) 2014 Elsevier Ltd. All rights reserved.