Fabrication of polypyrrole/nano-exfoliated graphite composites by in situ intercalation polymerization and their microwave absorption properties

Polypyrrole/nano-exfoliated graphite composites were synthesized using an in situ intercalation polymerization of pyrrole into the layers of expanded graphites. The morphologies and nanostructures of obtained composites were characterized by field emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. Results showed that the in situ intercalation polymerization of pyrrole cation into the layers of expanded graphites could separate graphite into nano-exfoliated graphite sheets. The interactions between polypyrrole and the graphite sheet were also confirmed by Fourier transformed infrared spectroscopy. The fabricated nanocomposites polypyrrole/nano-exfoliated graphite-1.5 showed obvious improvement in microwave absorption compared with those of the polypyrrole or the expanded graphite itself. With a thickness of 2.7 mm, the optimal absorption peak reached -48 dB at 13.4 GHz and the bandwidth corresponding to the reflection loss at -10 dB was 3.4 GHz (from 13.2 to 16.6 GHz). The minimum RL reached -34 dB with a thickness of 2.5 mm for Polypyrrole/nano-exfoliated graphite-1.5. Moreover, it could be observed that the absorption bandwidth with RL below -10 dB was obtained in the frequency range of 5-18 GHz for polypyrrole/nano-exfoliated graphite-1.5 with a thickness of 2-5 mm. This would open a path toward the fabrication of microwave absorption materials of light-weight. (C) 2014 Elsevier Ltd. All rights reserved.