Influence of the preparation conditions on the morphology of polyaniline electrodeposited by the pulse galvanostatic method

The pulse galvanostatic method (PGM) and galvanostatic method (GM) were used to electrodeposit polyaniline (PANI) in H2SO4 solutions. Scanning electron microscopy studies showed that PANI prepared with GM had a granular morphology similar to other researchers' results, whereas nanofibular PANI was prepared with PGM. Furthermore, the relationship between the synthetic conditions and morphology of PANI electrodeposited by PGM was investigated. Under some preparation conditions (i.e., mean current density of PGM = 1-4 mA cm(-2), ratio of the on-pulse period to the off-pulse period = 0.25-10, temperature = 10-30degreesC, and experimental frequency = 10-1000 Hz), nanofibular PANI was obtained, whereas flake PANI or granular PANI was prepared under other conditions. Nanosize PANI could result from the highly polarized current of the pulse current signal. The appropriate pulse peak current during the on-pulse period not only produced high electrochemical polarization but also did not lead to overoxidation of PANI; meanwhile, the monomer at the electrode/solution interface could be sufficiently supplied during the off-pulse period. (C) 2004 Wiley Periodicals, Inc.