Single- or double-layered porous films consisting of polysulfone (PSF) and cerium-activated yttrium silicate (CAYS) were prepared through the phase inversion of polymeric solutions. For a single-layered structure, a casting solution including n-methylpyrrolidone (NMP) as a solvent was cast on a glass substrate and solidified by immersing into a nonsolvent bath. In a double-layered structure, the bottom layer is a dense PSF film, prepared by vacuum coagulation of a methylene chloride/PSF solution. The top layer was formulated by coagulating the NMP solution, cast over the dense film, in a nonsolvent bath. The morphology and the radionuclide detection efficiency of the prepared films were significantly affected by the nonsolvent coagulants used. The water-coagulated, double-layered film showed a relatively clear-cut interface between the two layers, indicating the rapid coagulation of the second layer. On the contrary, the film coagulated by isopropanol retained well-developed sponge structures highly intertwined in the interface, associated with the delayed precipitation of the second layer. When spotted on the prepared films, radionuclides stayed mainly on the top surface of the isopropanolcoagulated film, but went deep into the substructure of the film coagulated with water. In comparison with the monolayered films, the double-layered ones improved the detection capacity of the spotted radionuclides, owing to the dense support layer. (c) 2005 Wiley Periodicals, Inc.