On the polymerization of p-phenylenediamine

1,4-Phenylenediamine polymerizes under oxidation with potassium persulfate to yield a polyquinoxaline, a material having a ladder structure and a fully oxidized state somewhat similar to that shown by pernigraniline. The structure assignment to the polymer is based on the comparison of the electronic spectra of pernigraniline with that of poly-p-phenylenediamine which show a strict analogy. Also the FT-IR and the H-NMR spectra support the proposed ladder structure composed an alternating sequence of benzenoid and quinoniimine moieties linked together by -NH- and =N- bridges. The specific conductivity of compressed pellets of the polymer is 6.3 x 10(-6) S/cm. On the other hand p-phenylenediamine does not polymerize during cyclic voltammetric studies but gives only low molecular weight oligomers and similar results are obtained by using ozone as oxidizing agent in place of potassium persulfate.