Doping of poly(o-phenylenediamine): Spectroscopy, voltammetry, conductivity and band gap energy

Abstract

In the present work, poly(o-phenylenediamine) (PoPDA) were synthesized by the chemical oxidation reaction of o-phenylenediamine (o-PDA) with ammonium persulfate ((NH4)2S2O8) (APS) as the oxidant. The chemical structure of the synthesized ladder type polymer was confirmed by UV–vis., FTIR, 1H NMR and TGA measurements. The synthesized polymer was doped by HCl, Cu(II), H3BO3, Fe(III), and I2 chemical agents. The doped forms of the polymer were examined by cyclic voltammetry (CV), UV–vis. absorption and FTIR spectroscopy. The HOMO, LUMO levels and band gap energies of the doped and undoped forms of the PoPDA were calculated by using UV–vis. adsorption and CV data. The band gap energy of undoped PoPDA was found as 2.25eV. In general the all dopants increased the band gap energy of the PoPDA. Also, the electrical conductivities of doped and undoped forms of PoPDA were measured. The electrical conductivity of undoped PoPDA was measured as 7.18×10−7S/cm. It was found that Fe(III) doping increased the electrical conductivity of PoPDA, while HCl, Cu(II), H3BO3 and I2 dopings decreased the electrical conductivity. The doped PoPDA polymer samples exhibited different optic, voltammetric and band gap behaviors.