PVDF/CFO-anchored CNTs ternary composite system with enhanced EMI shielding and EMW absorption properties

Lightweight, flexible electromagnetic interference (EMI) shields and electromagnetic wave (EMW) absorbers with low filler and improved impedance matching is the subject of intense global research. In this work, CoFe2O4@CNTs hybrids are synthesized in situ by solvothermal method and then the flexible PVDF/CoFe2O4@CNTs composites are prepared by solution casting. The content of CNT's in the CoFe2O4@CNTs hybrids was varied between 1 and 5 wt% of the CFO. These nano-inclusions (CoFe2O4/CFO) decorated CNTs) were dispersed in polyvinylidene fluoride (PVDF) with 7 wt%, 10 wt% and 15 wt%. The prepared systems were characterized using X-ray diffractometry, FTIR spectroscopy, transmission electron microscopy, vibrating samples magnetometry and vector network analyzer. TEM results show well dispersed CFO nanoparticles uniformly attached to the walls of CNTs, thus confirming their functionalization. Good impedance matching, which is a prerequisite for EMW absorption was observed for 7 wt% CFO@CNTs hybrid in PVDF which resulted in shielding effectiveness of 12.68 dB corresponding to 94.65% attenuation at a thickness of 1.88 mm. Moreover, EMW absorption properties of PVDF/CFO@CNTs composites were also studied by backing with metallic conductor where the same sample also showed the best minimum reflection loss (RLmin) of -26.09 dB at 11.26 GHz (bandwidth is 0.48 GHz). Excellent absorption properties are attributed to good impedance matching, effective dielectric and magnetic loss mechanisms and formation of 3D conductive networks which facilitates multiple reflection and scattering mechanism. (C) 2022 Elsevier B.V. All rights reserved.