membranes for fluid separation are disclosed . these membranes have a matrix layer sandwiched between an active layer and a porous support layer . the matrix layer includes 1 - d nanoparticles that are vertically aligned in a porous polymer matrix , and which substantially extend through the matrix layer . the active layer provides species - specific transport , while the support layer provides mechanical support . a matrix layer of this type has favorable surface morphology for forming the active layer . furthermore , the pores that form in the matrix layer tend to be smaller and more evenly distributed as a result of the presence of aligned 1 - d nanoparticles . improved performance of separation membranes of this type is attributed to these effects .