Facile synthesis of one-dimensional self-assembly oligo(o-phenylenediamine) materials by ammonium persulfate in acidic solution

The one-dimensional (1-D) self-assembly oligo(o-phenylenediamine) (OoPD) was prepared successfully by just mixing o-phenylenediamine (oPD) and ammonium persulfate (APS) in acidic solution at room temperature. The morphology and structure of the OoPD as-prepared were characterized by SEM, FTIR, NMR and MS. Results showed that the product was identified as dimer and trimer with the phenazine-like structure. Especially the OoPD synthesized by oxidant APS in the acidic solution showed self-assembly behaviors to form definite 1-D microfibrils. Increasing the solution pH after the oxidative oligomerization can effectively improve the 1-D microstructure's rigidity. A possible formation mechanism was proposed.