γ-MnO2/polyaniline composites: Preparation, characterization, and applications in microwave absorption

Abstract MnO 2 /doped polyaniline (PANI) is prepared by an in situ polymerization method using γ-MnO 2 as the addition agent and hydrochloric acid as the doping agent. Products are characterized by FT-IR, UV–vis, XRD, and TEM. Conductivity, electromagnetic properties, and microwave absorption properties are first discussed on the basis of structural characterization. The as-prepared products of MnO 2 /PANI are partially crystalline in nature and spherical in pattern with grain sizes of 50–70 nm. MnO 2 particles are successfully decorated with doped PANI. MnO 2 /PANI displays moderate electric conduction, excellent dielectric losses, and microwave absorption capabilities. Compared to pure MnO 2 , the dielectric and reflection loss properties of MnO 2 /PANI composites exhibit significant improvements, with an effective absorption band at 5 GHz under −10 dB and maximum reflection loss of −21 dB at 13.56 GHz. Pure MnO 2 shows an effective absorption band of 3 GHz under −10 dB and a maximum reflection loss of −14.20 dB at 11.5 GHz. Thus, MnO 2 /PANI composites are found to be a promising microwave absorption material.