Template-free electrochemical synthesis of superhydrophilic polypyrrole nanofiber network

In this work, a superhydrophilic polypyrrole (PPy) nanofiber network is electrochemically synthesized in an aqueous solution by using phosphate buffer solution (PBS) in the absence of templates, surfactants and structure-directing molecules. FESEM, X-ray diffraction, UV-visible absorption, and contact angle measurement were employed to characterize the nanofiber network. The effect of synthetic conditions including pH, oxidation potential and concentrations of phosphate, pyrrole (Py) and dopant ClO4- on the PPy nanostructure is systematically investigated. A mechanism for the nanofiber formation in an aqueous solution without assistance of any "hard" and "soft" template is proposed, in which the presence of the hydrogen bonding between phosphate and Py oligomers is essential to producing the ID nanofiber structure, and the electrostatic interactions between ion dopant and Py oligomers lead to an irregular nanostructure. This is a simple, environmentally friendly and one-step approach to fabricate a PPy film with unique nanostructure and chem-physical properties, which can have great potential in various applications such as sensors, electronics, and energy source systems.