In situ synthesis of core-shell nanocomposites based on polyaniline/Ni-Zn ferrite and enhanced microwave absorbing properties

Core-shell nanocomposites based on polyaniline/Ni-Zn ferrite (PANI-NZFO) were successfully fabricated by a method of in situ oxidative polymerization, and the aggregation of Ni-Zn ferrite (NZFO) nanospheres can be controlled through adjusting the weight ratio of NZFO/aniline (NZFO/ANI). As a result, the sample with NZFO/ANI weight ratio of 3:100 exhibits the optimal reflection loss (RL) value of - 46.5 dB. Particularly, PANI-NZFO present excellent dielectric loss (0.18 < tan delta(e) < 0.35) due to the coating of PANI. TEM images show the core-shell structure of PANI-NZFO and the dispersibility of NZFO is favorable. In order to avoid the NZFO nanospheres from being damaged by the acid, their surface was firstly grafted with amidogen (-NH2). Simultaneously, it is clear that the NZFO nanospheres haven't been destroyed during the process of coating, which has been confirmed by XRD patterns, and a formation mechanism was designed. FTIR spectra indicate that the coating observed in TEM images is exactly polyaniline (PANI). The effects of NZFO/ANI weight ratio (or conductivity), volume fraction (of PANI-NZFO/paraffin containing PANI-NZFO) and layer thickness on microwave absorbing properties were investigated at room temperature in the frequency range of 0-18 GHz.