Synthesis of polyaniline by chemical oxidative polymerization and characteristic of conductivity and reflection for various strong acid dopants

Herein, polyaniline (PANI) is synthesized via chemical oxidative polymerization of aniline monomer with ammonium persulfate as initiator by maintaining the flow rate and stirring for 8 h at room temperature. Particle sizes up to 54.716 μm are obtained, with a viscosity reaching 1.87 mPa-s at 270 min. The highest temperature during polymerization was 32 °C at 210 min. Thus, the polymer molecules undergo propagating process to form polymer chains. Fourier transform infrared spectroscopy confirms the presence of the PANI molecule, which reveals a complete reaction when the double-bond peak at 3442 cm⁻¹ disappears from the spectrum and new peaks appear corresponding to benzoic and quinoid molecules at 1300-1600 cm⁻¹. This ensures that all aniline molecules are converted to PANI with no residual. We conclude that PANI is synthesized via oxidative polymerization. The electrical conductivity of PANI is driven by protonic acids. The conductivity increases upon adding protonic acids as a strong acid-doping agent. Thus, PANI-HClO₄ exhibits best conductivity. The best material candidate for a microwave-absorbing material is thus PANI-EB because it has the highest reflection loss at -29.69 dB at 11.812 GHz, whereas PANI-HClO₄ has only -2.74 dB reflection loss at 12.400 GHz.