Polyaniline (PANI) nanotubes were chemically synthesized with the introduction of 4-sulfobenzoic acid monopotassium salt (KSBA) into an aqueous solution. As opposed to PANI microplates synthesized in the absence of KSBA, the PANI polymerized with KSBA exhibited tubular morphology, tens of micrometers long, with a total diameter of 130-240 nm, an inner diameter of 10-100 nm, and a wall thickness of 60-70 nm. The formation yield of PANI nanotubes was as high as about 95%, and the electrical conductivity was 4.8 x 10(-1) S cm(-1). However, the PANI microplates exhibited about 10 times lower electrical conductivity of 3.1 x 10(-2) S cm(-1) than PANI nanotubes. The morphologies of the final PANIs were greatly affected by the morphologies of the oligoanilines produced with or without KSBA in the early polymerization stage. In this study, KSBA was introduced to regulate the reactant pH and to control oligoaniline morphology (with KSBA: 1D long nanosheets, without KSBA: 2D microplates). Synthetic time-resolved morphology dynamics revealed that the oligoanilines play a key role as templates for the PANI nanosheets polymerized by anilinium cations. Finally, the nanosheets transform into long PANI nanotubes through conformational changes induced by the protonation of the PANI chains in a highly acidic medium. Interestingly, the final products are a simple mixture of pure PANI nanotubes and oligoaniline complexes composed of oligoanilines and aniline sulfate salts. Thus, the oligoaniline do not grow into the PANI chains but function only as templates for the 1D PAN! formation. (C) 2010 Elsevier Ltd. All rights reserved.