Spiny polyaniline (PANI) spheres (urchin-like) were coated on a poly(tetrafluoroethylene) (PTFE) membrane via a counter-diffuse interfacial oxidation polymerization of aniline in an aqueous medium. The produced composite membrane has both unexpected superhydrophilicity and conductivity. The microstructure and morphology of the composite membrane were characterized by FTIR, UV-vis, XRD, TGA, and SEM. Effects of reagent concentrations and polymerization time on the membrane morphology and properties were studied systematically. A possible formation mechanism of the urchin-like polyaniline nanospheres on PTFE surface has been briefly discussed. The co-effect of both spherical micelles formed by Nafion and nanofibrous micelles formed by aniline/p-toluenesulfonic acid was considered to be a reason to produce the urchin-like PAN! nanospheres. The PTFE/Nafion/PANI composite membrane showed a convertible hydrophilic/hydrophobic feature via adjusting acidity/alkalinity of an aqueous medium and also was able to adsorb heavy metal-ions from the medium. (c) 2012 Elsevier Inc. All rights reserved.