Synthetic Metals 161 (2011) 1682–1685 Contents lists available at ScienceDirect Synthetic Metals j o ur nal homep ag e: www.elsevier.com/locate/synmet Synthesis of polypyrrole–Nafion composite films by gas phase electroformation Abdulazeez. T. Lawal a,∗ , Gordon G. Wallace b a Department of Education and Training, NSW 2000, Main street, Blacktown, Australia b IPRI University of Wollongong, NSW 2522, Australia a r t i c l e i n f o Article history: Received 1 February 2011 Received in revised form 1 June 2011 Accepted 3 June 2011 Available online 16 July 2011 Keywords: Composite Polypyrrole Gas phase Nafion Electroformation a b s t r a c t Nafion was introduced into polypyrrole (PPy) matrix by gas phase electrochemical polymerisation. This produced a uniform, homogeneous and conductive thin film of composite polymer. The films (PPy/Nafion) also show surface features of highly ordered structural regularity. The composites obtained were char- acterised by cyclic voltammetry (CV) and redox performance were investigated. The relationship of the anodic current of the composite with the various experimental parameters such as concentration of Nafion, current density, polymerisation time and temperature were investigated. Anodic current increases with the Nafion concentration, polymerising time, temperature and current density. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved. 1. Introduction Polypyrrole (PPy), polyaniline (PANi), and polythiophene (PT) are all -conjugated conducting polymers. They have attracted a great deal of attention as electronic conductors. They are usu- ally polymerised and simultaneously doped using electrochemical techniques in solution. Among these conducting polymers, PPy has superiority over other conducting polymers for commercial appli- cations because of its unique properties, such as good electrical conductivity, excellent environmental stability and ease of prepa- ration [1–4]. Conducting polymer composites have been used as gas sensitive materials, with the advantages of low cost, easy preparation, high sensitivity and sensing at room temperature. Han et al. and Winey et al. [5,11] synthesised composite PPy-CNT using electrochemical deposition method. In recent years, conduct- ing polymer/inorganic nanoparticles composites were fabricated in order to improve gas sensor sensitive properties. Forming compos- ite with polymers has been used for improving sensing capabilities of NH 3 and HCl gas sensors. For example, polypyrrole/Nafion com- posite were used as fuel cells [6–9] and were also used in a solid polymer electrolyte battery [6,10]. Recently, a variety of methods have been used for producing composites from the combination of carbon nanotubes (CNTs) with conducting polymers [11–15]. Han et al. [11] synthesised composite films of PPy-CNT using the ∗ Corresponding author. Tel.: +61 242742664. E-mail address: Abdulazeez.lawal@det.nsw.edu.au (Abdulazeez.T. Lawal). electrochemical deposition method. An et al. [15] fabricated a CNT- PPy composite by chemical polymerisation of the pyrrole monomer with a CNT. The gas sensitivity of this composite was about 10 times higher than that of PPy. Lee et al. directly synthesized PPy-CNTs composite films, hav- ing high conductivity and uniformity, by depositing polymerisation in the gas-phase [13]. The conductive polypyrrole was filled as a matrix material between the CNT networks by self-organization of the pyrrole monomer. A composite of multi-walled carbon nan- otubes (MWCNTs) and polypyrrole (PPy) has been synthesized by vapour phase polymerisation, and characterized by Fourier trans- formed infrared spectra, Raman spectra, thermal gravimetric anal- ysis, X-ray diffraction study and scanning electron microscopy [11]. Spin coating, solvent casting, ink-jet printing, chemical oxida- tion and single dip of substrate into polymerising aqueous solution are the most common methods used for depositing ultra thin and even conducting polymer film on a substrate. PPy is not soluble in most solvents; thus it is difficult to deposit PPy using most of these techniques. Electrochemical polymerisation which usually gives thin coating of high quality has thus been used for depositing PPy onto a conducting substrate [11,16,17]. Vapour phase polymerisa- tion is another fast method of depositing thin and uniform film. It has been proven to be the most efficient method to achieve uniform coating [18]. Mohammadi et al. [18] conducted the first studies of vapour phase polymerisation of conducting PPy using iron (1 1 1) chloride H 2 O 2 as oxidants at low pressure and several other researchers used normal pressure for their vapour phase polymerisation [3,18,20–23]. 0379-6779/$ – see front matter. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.synthmet.2011.06.003