Electrosynthesis of poly(o-phenylenediamine) in ionic liquid and its properties

Ionic liquid 1-ethyl-3-methylimidazolium bromide ([EMIM]Br) and N-methylimidazolium tetrafluoroborate ([HMIM]BF₄) have been used as solvent and electrolyte for the electropolymerization of o-phenylenediamine at glassy carbon electrode by cyclic voltammetry. It was found that monomer was more easily oxidized in ionic liquid than acidic aqueous solution, and oxidative potential was reduced by 0.725 and 0.455 V, respectively. Electrode modified with poly(o-phenylenediamine) (PPD) has obvious electrochemical activity in acid solution (pH 1-4). The apparent diffusion coefficient (D _app) of PPD film is measured by chronocoulometry and chronoamperometry. The polymer structure is measured by UV and IR. IR spectrometry reveals that poly(o-phenylenediamine) has phenazine ring structure. The heat stability of polymer is observed from thermogravimetry.