Dielectric characteristics of multiwall carbon nanotube-filled polyaniline

The dielectric properties of in-situ polymerized polyaniline-multiwalled carbon nanotubes (PANI/MWCNTs) nanocomposite sample were analyzed as a function of temperature (153–353 K) and applied frequency (1 Hz–1000 KHz) over a wide range. To introduce heterogeneity in PANI, MWCNTs (4 wt%) were embedded into the PANI matrix during the polymerization, whereas, to control the electrical conductivity, the synthesized material was reduced via chemical treatment with ammonia. FTIR spectroscopy studies confirm the synthesis of PANI/MWCNTs nanocomposite in lower conducting (emeraldine base) dielectric state. X-ray diffraction (XRD) pattern of the prepared sample reveals the semi-crystalline nature. Thermogravimetric analysis (TGA) investigation indicates that synthesized sample is more stable even at 800 °C. The dielectric studies reveal that the static dielectric constant of the prepared sample enhances with the enhancement in temperature and found to decrease with applied frequency. The enhancement in dielectric constant with temperature may be associated with the enhancement in mobility of the electric dipoles in the conducting polymer. The dielectric constant for the reduced PANI/MWCNTs composite (i.e. ∼1170) is high as compared to reduced pristine PANI (i.e. ∼538). The value of dc electrical conductivity has been decreased from 77 S/cm to 7.81x10−10 S/cm due to reduction of PANI/MWCNTs nanocomposite which indicates the enhancement in dielectric properties. The ac electrical conductivity of synthesized nanocomposite was also found to enhance with an increase in operating temperature, which may be endorsed to the enhancement in activated trapped charge carriers' concentration.