In order to obtain efficient microwave absorbers that possess high conductivity, dielectric and magnetic properties, hexanoic acid doped polyaniline (PAni) nanocomposites which contain different ratios of ferum (II) oxide (Fe3O4) and titanium dioxide (TiO2) nanoparticles were successfully prepared by in situ chemical polymerization through template free method. Chemical structure, conductivity, morphology, thermal stability, magnetic properties, and amorphous/crystalline behavior of PAni nanocomposites were characterized by Fourier transform infrared spectrometer (FTIR), four point probe, field emission scanning electron microscope (FESEM), thermal gravimetric analysis (TGA), vibrating samples magnetometer (VSM), and X‐ray diffractometer (XRD), respectively. From this study, conductivity was significantly improved from 8.48 × 10−4−1.23 × 10−2 S/cm for PAni nanocomposites without any chemical treatment (during addition of Fe3O4) to 3.58 × 10−2−4.77 × 10−2 S/cm for those with chemical treatment. PAni nanocomposites with chemical treatment show a narrow sharp reflection loss (RL) peak with high absorption (−48.9 dB) at lower frequency due to the limited individual Fe3O4 nanoparticles outside the nanorods/nanotubes as proved by the new proposed mechanism (Fig. ), while it shows a broad RL peak with poor absorption (−13 dB) at higher frequency for those without chemical treatment. The novelty of this research has been focused on PAni with chemical treatment which yield better microwave absorption property (99.999% absorption), combination of high conductivity (3.58 × 10−2−4.77 × 10−2 S/cm), high heterogeneity and moderate magnetization (Ms = 8.87–28.49 emu/g) compare to the PAni without chemical treatment. POLYM. COMPOS., 34:1186–1194, 2013. © 2013 Society of Plastics Engineers

Hexanoic acid (HA) doped polyaniline (PAni) nanocomposites which consist of different contents of untreated double wall carbon nanotubes (u‐DWNT) and carboxyl treated DWNT (c‐DWNT) with titanium dioxide nanoparticles were successfully prepared using template‐free method. Fourier transform infrared, ultraviolet‐visible and X‐ray diffractometer spectra clearly confirmed the chemical structure of PAni nanocomposites. Thermal stability, morphology, conductivity, magnetic properties and reflection loss of PAni nanocomposites were characterized by thermogravimetric analyzer, field emission scanning electron microscope, four‐point probe, vibrating sample magnetometer and microwave vector network analyzer, respectively. From this study, it is shown that electrical conductivity of PAni nanocomposites with u‐DWNT possessed higher conductivity (1.23 × 10–1 to 1.31 × 100 S/cm) compared to c‐DWNT (3.43 × 10–2 to 4.48 × 10–1S/cm). PAni/HA/TiO2/DWNT nanocomposites with 20% of c‐DWNT have been covered by PAni layers to form the highest amount of nanorods/nanotubes. Hence, it shows high heterogeneity that will enhance the dielectric permittivity and contribute to a more disordered motion of charge carriers along the PAni backbone. Therefore, it will eventually contribute to good microwave absorption and potentially apply as an efficient electromagnetic interference shielding material in cell phones. POLYM. COMPOS., 39:1283–1291, 2018. © 2016 Society of Plastics Engineers