Electrical and Dielectric Properties of Polyaniline Doped with Carboxyl‐Functionalized Multiwalled Carbon Nanotube

Polyaniline nanocomposites containing various concentrations of carboxylic acid functionalized multiwalled carbon nanotubes (PANI/c‐MWCNT) were synthesized by in situ chemical oxidation polymerization of aniline monomer using ammonium persulfate in the absence of any added acids. The electrical conductivity measurements evidenced the effect of COOH groups of c‐MWCNTs on PANI units. The morphology of PANI/c‐MWCNT nanocomposites was studied using transmission electron microscopy and scanning electron microscopy techniques. The uniform and thick coating of PANI on the c‐MWCNT surface was observed. The electrical conductivity of PANI/c‐MWCNT (3 wt%) nanocomposite is recorded about three orders of magnitude higher than that of pure PANI. In addition, the increase in the conductivity with respect to temperature revealed the semiconductor behavior of the nanocomposites. Similarly, the dielectric permittivity of the nanocomposites enhanced from 3.34 to 10.2 at 1 kHz as the c‐MWCNT concentration increased from 0.5 to 3 wt%. The loss tangent was still low (<0.025) even at a higher concentration of c‐MWCNT, i.e., 3 wt%. The response of permittivity to temperature is increased with increasing the c‐MWCNT concentration in the nanocomposite.