Abstract

Currently, there is a considerable demand for materials with inter-balanced dielectric properties to replace the existing traditional insulators in variegated electronic appliances over the range of audio and radio frequency. In the current work, a one-step facile electrospun (E-spun) technique is adopted to fabricate a non woven mat consisting of nano-scale conducting fibers of polyaniline (PANI) and gold nanoparticles (AuNPs) using polyvinyl alcohol (PVA) as a binder. The influence of different amounts of the AuNP solution on the size and distribution of fibers was investigated using high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). The dielectric constant, losses, AC conductivity and modulus of nanofibers were investigated over a wide frequency and temperature range of 0.1 Hz to 10 MHz and -40 degrees C to 60 degrees C respectively by means of Broadband Dielectric Spectroscopy (BDS). AC conductivity varies as a function of frequency, according to Jonscher's power law (JPL), and the behavior of the temperature dependent frequency exponent using JPL suggests that the Correlated Barrier Hopping (CBH) is the dominant charge transport mechanism for conducting nanofibrous nonwoven mats. By using the CBH model the maximum barrier height, hopping distance and density of state (DOS) were calculated for the whole temperature range. The incremental increase from 1.6 x 10(-6) S cm(-1) to 2.5 x 10(-6) S cm(-1) with increasing amounts of AuNP solution was noticed and is ascribed to the corresponding increased conducting network and reduced trapping centers in the mat. Dielectric constant increases with both increased loading of nanoparticle solution in the mat and the increased temperature, which may be attributed to enhanced interfacial polarization. Shifting and broadening of well-defined peaks were observed in the imaginary part of the dielectric modulus spectrum, indicating Maxwell-Wargner-Sillars (MWS) interfacial polarization. Effective electromagnetic (EM) shielding was also evaluated for all compositions and a sharp peak of 22.99 dB (>99%) at 11.18 GHz was noticed for a 0.5 mm thick mat of the composite. This was observed to be dependent on the concentration of AuNPs and the thickness of the mat.