UV-Catalytic Preparation of Polypyrrole Nanoparticles Induced by H₂O₂

As a green oxidant, H₂O₂ can be used to induce the polymerization of pyrrole. This approach avoids the issue of metal residue in the polymer caused by metal oxidants, whereas the reaction efficiency is low and the corresponding reaction mechanism not clear. In this study, uniform polypyrrole (PPy) nanoparticles were prepared using H₂O₂ as an oxidant under UV irradiation in the presence of polyvinylpyrrolidone (PVP). The morphology characterization indicated that the spherical PPy nanoparticles were capped by a PVP shell. Through the investigation of reaction process, it was found that the photolysis of H₂O₂ led to the formation of hydroxyl radicals, which then initiated the oxidative polymerization of pyrrole. The coalescence of small PPy particles formed nanoparticles which were stabilized by PVP. The effects of several reaction conditions on the polymerization rate and the size distribution of nanoparticles were investigated in detail, including radiation intensity (0-30 W), temperature (0-50 °C), and the concentrations of PVP (5-20 g/L), H₂O₂ (0.06-0.6 M), H₂SO₄ (0-0.22 M), and the monomer pyrrole (0.03-0.2 M), respectively. UV-catalytic preparation of PPy nanoparticles induced by H₂O₂ is an effective and environmentally friendly approach, which could be expected to be extended to other conductive polymers.