3D-Polypyrrole Hydro-Sponge Thin Films for Electrochemical Applications

Conducting polymers have been targeted as research interest in many publications and it is possible to find applications in drug delivery systems, artificial muscles, artificial neurons, tissue engineering, supercapacitors, etc.  All this interest about conducting polymers comes from their unique properties such as, high conductivity, chemical stability, versatility and biocompatibility. At the present moment, not only the properties of the materials are important but also the ability to control their morphology is a goal, because this can lead to the improvement of the materials to be applied in different technologies. This work reports the controlled electrochemical synthesis of polypyrrole hydro-sponges (Ppy-HS) thin films nanostructured with methyl orange (MO) template. The Ppy-HS thin film was synthesized on a gold surface using chronoamperometry. The synthesis was performed in 5 mmol L-1 MO aqueous solution to which 35 μL of distilled pyrrole (Py) were added to a final volume of 10 mL. The pH of the solution was adjusted to 2 by the addition of HCl. A three electrodes system was mounted using gold, Ag/AgCl/NaCl-3M electrode and platinum as work, reference and auxiliary electrodes, respectively. Different Ppy-HS thin films were synthesized at 0.6 V using different electrochemical charge of polymerization. Scanning Electron Microscopy (SEM) characterization showed that the Ppy-HS presents a microfibrillar structure organized as a 3D material. However, it is possible to control the morphology of the Ppy-HS by the electrochemical charge of polymerization. Under the microfibrillar there is a compact layer with the typical granular structure of Ppy. After that, the increase of the electrochemical charge used in the polymerization results in the increase of the density of the microtubules to form a 3D structure. The 3D porous structure makes the Ppy-HS a very interesting material for many technological applications. The material presents good elastic properties, high water uptake, and enhanced electroactivity. All these characteristics allows the application of PPy-HS in biosensors, drug delivery, tissue engineering and in other areas. In this work, the Ppy-HS is being explored in storage energy field. This material shows a specific capacitance of 800 F/g, which is much higher compared with no-strucutured Ppy and comparable to other materials applied in the field. References: Daí, T.; Lu, Y. J. Mat. Chem. 2007, 17, 4797. Antonio, J. L. S.; Lira, L. M.; Gonçales, V. R.; Córdoba de Torresi, S. I. Electrochim. Acta 2013, 101, 216.