A porous membrane, The porous membrane includes a triblock copolymer of the formula ABC, the porous membrane comprising a plurality of pores; wherein the A block has a Tg of 90 degrees Celsius or greater and is present in an amount ranging from 30% to 80% by weight, inclusive, of the total block copolymer; wherein the B block has a Tg of 25 degrees Celsius or less and is present in an amount ranging from 10% to 40% by weight, inclusive, of the total block copolymer and wherein the C block is a water miscible hydrogen-bonding block immiscible with each of the A block and the B block; wherein the porous membrane comprising a first major surface and an opposed second major surface, wherein the first major surface is a nanostructured surface.