Growth of Polyaniline Nanoneedles on MoS2 Nanosheets, Tunable Electroresponse, and Electromagnetic Wave Attenuation Analysis

The purpose of this work was to fabricate highperformance dielectric materials for electrorheological (ER) application and electromagnetic (EM) wave attenuation. Commercial MoS2 bulks were exfoliated into nanosheets via combination of ball-milling and bath sonication procedures, which were used as the template for in situ grafting of PANI nanoneedles (PANI-NDs) to afford MoS2/PANI-NDs. The length diameter (LID) ratio of PANI-NDs on MoS2 nanosheets was feasibly tuned via modulating the polymerization time. Therefore, the tunable electrical conductivity and dielectric properties of the obtained MoS2/PANI-NDs were achieved. Compared with bare MoS2 nanosheets, MoS2/PANI-NDbased ER fluids constructed more robust fibril-like structure governed by the external electric energy and exhibited higher dynamic yield stress (186.8 Pa at 3 kV/m_m) with wider applied electric field strength (0-3.0 kV/mm). Furthermore, as a novel EM wave absorbing material, the maximum reflection loss (RL) values of MoS2 nanosheets reached 44.4 dB at 11.48 GHz with the thickness of 3.0 mm, while the similar RL values of MoS2/PANI-NDs (-44.8 dB) reached 14.5 GHz with the thickness of only 1.6 mm. The broad effective EM absorption bandwidth (RL values less than -10 dB) for MoS2/PANI-NDs was observed owing to the synergistic effect of PANI-NDs and MoS2 nanosheets.