Energy storage and surface protection properties of dianiline co-polymers

Abstract

Conducting co-polyanilines of alkyl/alkoxy substituted anilines with dianiline, namely poly(OT–DA), poly(OA–DA) and poly(DMA–DA), have been synthesized chemically from o-toluedine(OT), o-anisidine(OA), 2,6-dimethylaniline(DMA) and N-phenyl-p-phenylenediamine (DA). These co-polyanilines were characterized by spectral, thermal and electrochemical techniques. The conductivities of phosphoric acid (PA) doped co-polydianilines are 2.26 × 10⁻¹ S cm⁻¹ for poly(OT–DA), 7.94 × 10⁻² S cm⁻¹ for poly(OA–DA) and 9.25 × 10⁻² S cm⁻¹ for poly(DMA–DA) at room temperature. The thermal stability of co-polymers is higher in the doped state than in the emeraldine base state. A capacitor has been fabricated using these polymers using stainless steel electrodes. The specific capacitance of the device is 177 F g⁻¹ for poly(OT–DA)–PA, 110 F g⁻¹ for poly(OA–DA)–PA and 121 F g⁻¹ for poly(DMA–DA)–PA at 1 mA cm⁻² current density. The anti-corrosion behaviour of co-polydianilines (EB state) coated on mild steel (MS) electrode was investigated by Tafel polarization method and the corrosion rate is found to be 2.07 × 10⁻⁶ mm per year for poly(OT–DA)–EB, 1.42 × 10⁻⁵ mm per year for poly(OA–DA)–EB and 5.3 × 10⁻⁴ mm per year for poly(DMA–DA)–EB.