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

MnO2/doped polyaniline (PANI) is prepared by an in situ polymerization method using gamma-MnO2 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 MnO2/PANI are partially crystalline in nature and spherical in pattern with grain sizes of 50-70 nm. MnO2 particles are successfully decorated with doped PANI. MnO2/PANI displays moderate electric conduction, excellent dielectric losses, and microwave absorption capabilities. Compared to pure MnO2, the dielectric and reflection loss properties of MnO2/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 MnO2 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, MnO2/PANI composites are found to be a promising microwave absorption material. (C) 2011 Elsevier B.V. All rights reserved.