The construction of polyaniline (PANI) chains in the interfacial polymerization was controlled by introducing isopropanol (IPA) as a co-solvent into aqueous phase. The influences of the IPA content on the morphology, microstructure and electrochemical behaviors of PANI products were investigated by field emission scanning electron microscopy, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis as well as electrical and electrochemical measurements. It is found that the growth and migration of PANI molecules strongly depended on the IPA content through tuning the hydrogen-bonding strength between PANI chains and IPA molecules. With the increasing of the IPA content, the role of IPA played on the construction of PANI chains changed gradually from promoting the formation of PANI nanofibers to inhibiting the migration of PANI molecules into aqueous phase, which would result in more irregular shaped particles. Moreover, PANI electrode at the current density of 1 A g(-1) reached its greatest specific capacitance of 539 F g(-1) at 5% IPA content, with a secondary maximum of 475 F g(-1) for 50% IPA content in aqueous phase, which were both higher than 444 F g(-1) for the nanofibers prepared in the absence of IPA. It is demonstrated that a great enhancement on the capacitive properties can be achieved by introducing a small amount of IPA which would be of benefit to promote the formation of PANI nanofibers with larger ratio of height to diameter. (C) 2017 Elsevier Ltd. All rights reserved.