We have made triblock terpolymer membranes of polylactide, polydimethylacrylamide and polystyrene that self-assemble into a cylindrical structure.  The lactide block is then removed by etching, giving membranes with relatively monodisperse 14 nm pores.  An example is shown below.  In the cylindrical structure, these pores show gas mass transfer and liquid flow quantitatively consistent with Knudsen diffusion and with the Hagen-Poiseuille law, respectively.  Using the related bicontinuous gyroid structure, the polymers promise easily manufactured thin films with tunable nanopores from 2 to 100 nm in diameter