Microwave Absorption Properties of Polyaniline/Titanium Dioxide (PAni/TiO2) Doped with Different Types of Fullerenes

Abstract

In this work, Polyaniline/titanium dioxide (PAni/TiO2) nanocomposites without and with addition of fullerene such as pristine fullerene (C60) and small gap fullerene (S.G.F) were prepared through template‐free method by using hexanoic acid (HA) as a dopant. FTIR and UV‐Vis spectra confirmed the chemical structure of conjugated PAni and indicated that the resulted PAni is in conducting state. The existence of fillers in PAni nanocomposites were confirmed by the characteristic peaks of TiO2 and fullerene in XRD pattern. Based on FESEM images obtained, nanocomposites formulated with C60 (PAni/HA/TiO2/C60) formed the nanorods/nanotubes and microrods/microtubes with the biggest diameter (240 nm), followed by PAni with S.G.F (PAni/HA/TiO2/S.G.F) and PAni without the addition of fullerene (PAni/HA/TiO2) with diameter of 180 nm and 160 nm, respectively. Besides, PAni/HA/TiO2/C60 also possessed the highest electrical conductivity of 1.708 × 10−1 S/cm as compared to PAni/HA/TiO2/S.G.F and PAni/HA/TiO2 (4.531 × 10−3 S/cm to 1.439 × 10−2 S/cm). Microwave absorption studies of PAni nanocomposites were carried out by using Microwave Vector Network Analyzer (MVNA) in the frequency range of 0.5–18.0 GHz. Among all nanocomposites, PAni/HA/TiO2/C60 exhibited a narrow and the highest reflection loss (RL) peak of −61.3 dB at 9 GHz due to the highest conductivity (1.708 × 10−1 S/cm), dielectric permittivity (0.46) and heterogeneity of PAni (larger amount of nanorods/nanotubes and microrods/microtubes) that have induced more disordered motion of charge carrier along the backbone of PAni. Thus, it eventually enhanced the molecular polarization such as greater space charge relaxation and hopping of confined charges.