Synthesis Of MnO₂@PANI Composites And Its Microwave Absorption Properties

MnO₂@PANI composites with four shapes of square,solid sphere,hollow sphere and sea urchin were prepared by using MnSO₄·H₂O,KMnO₄ and aniline?AN?as raw materials,and their electromagnetic wave absorption properties were studied.The composites were characterized by XRD?X-ray diffraction analyzer?,FT-IR?Fourier transform infrared spectrometer?,SEM?scanning electron microscopy?,TEM?transmission electron microscopy?and VNA?vector network analyzer?.The results are as follows:?1?The MnSO₄·H₂O was used as the manganese source to prepare the MnCO₃.The MnCO₃ precursor was calcined in air to obtain the cube MnO₂.APTES?3-aminopropyltriethoxysilane?and PVP?polyvinylpyrrolidone?were used to modify the surface of cube MnO₂ to induce in situ polymerization of aniline on the surface of cube MnO₂.Finally,cube MnO₂@PANI?CMP?composites were obtained.The effects of morphology and structure of the composites,mass ratio of MnO₂ to PANI on the microwave absorbing properties of the composites were studied.The results show that:The MnO₂ is a square material with a side length of 1.5-2?m and maintains the morphology of the MnCO₃ precursor well.After compounding with PANI,a core-shell composite is obtained.The absorbing performance test shows that the addition of PANI significantly enhances the absorbing properties of the composites,and the absorbing property first increases and then decreases with the increase of PANI mass ratio.When the mass ratio reaches 1:3,the maximum reflection loss of the composite at 6.16 GHz is-36.49 dB,and the matching thickness is 4 mm.?2?Solid sphere MnO₂ were synthesized by calcining the MnCO₃ precursor and hollow sphere MnO₂ was prepared by self-template method of MnCO₃.The solid sphere MnO₂ and hollow sphere MnO₂ modified by APTES and PVP were compounded with PANI to obtain solid sphere MnO₂@PANI?SMP?and hollow sphere MnO₂@PANI?HMP?composites.The effects of morphology and structure of the composites,mass ratio of MnO₂ to PANI on the microwave absorbing properties of the composites were studied.The results show that the diameter of the solid sphere and hollow sphere MnO₂ is 2-2.5?m.After the solid sphere MnO₂ and hollow sphere MnO₂ are combined with PANI,the electromagnetic wave absorption performance of the composite is significantly enhanced,and the performance of both is better than that of the cube MnO₂@PANI composite.When the mass ratio of MnO₂ to PANI in the solid sphere MnO₂@PANI composite is 1:3,the maximum reflection loss value of the composite at 6.8 GHz is-40.46 dB,the matching thickness is 4 mm;when the mass ratio of MnO₂ to PANI in hollow sphere MnO₂@PANI composite is 1:3,the composite has 4.56 GHz broadband absorption,and the maximum reflection loss at 8.48 GHz is-52.06 dB,and the matching thickness is 3 mm.?3?Urchin-like MnO₂ was prepared by hydrothermal method using KMnO 4 as manganese source.APTES and PVP were used to modify the surface of urchin-like MnO₂.Urchin-like MnO₂@PANI?UMP?composites were synthesized by in-situ polymerization of aniline.The morphology and structure of the composites,the mass ratio of MnO₂ to PANI,and the microwave absorption properties of the composites were studied.The results show that urchin-like MnO₂ is composed of MnO₂ nanorods.The length and diameter of MnO₂ nanorods are in the range of 600-700 nm and 20-50nm,respectively.When the mass ratio of MnO₂ to PANI in the urchin-like MnO₂@PANI composite is 1:4,the composite has an effective absorption bandwidth of 6 GHz,the maximum reflection loss at-10.24 GHz is-40.95 dB,and the matching thickness is 3 mm.?4?The absorbing properties of the four morphologically structured MnO₂@PANI composites are as follows:hollow sphere composites are optimal,due to the hollow structure can cause multiple reflection loss and interfacial polarization of electromagnetic waves;secondly,urchin composites,MnO₂ The nanorod can be used as an antenna receiver to receive more electromagnetic waves into the material for loss;the electromagnetic wave absorption performance of the solid sphere MnO₂@PANI and the cube MnO₂@PANI composite is weak.Figures[22]Tables[10]References[104].