Evidence of Hopping Charge Transport and Interfacial Polarization in Carbon Black Doped Polypyrrole Nanocomposites: A Broadband Dielectric Study

ABSTRACT This study investigates dielectric relaxation, electrical conductivity, and charge transport mechanisms in pristine polypyrrole (PPy) and carbon black (CB)–doped polypyrrole (PPy/CB) composites synthesized via in situ polymerization. Structural and morphological characterization using XRD, FTIR, Raman spectroscopy, and SEM confirms the successful incorporation and homogeneous dispersion of CB within the PPy matrix. Broadband dielectric spectroscopy (BDS) measurements carried out over the frequency range of 10 −1 –10 7 Hz reveal a systematic evolution of dielectric and transport behavior with increasing CB content. The dielectric constant ( ε ′) decreases with CB loading, indicating a transition from polarization dominated dielectric behavior to conduction dominated electrical response. DC conductivity increases markedly from nearly insulating pristine PPy to 0.032 S cm −1 for the PPy/CB composite containing 10 wt% CB. The frequency dependent AC conductivity follows Jonscher's universal power law with exponent values between 0.5 and 0.7, suggesting charge transport via localized hopping in a disordered system. Cole–Cole model analysis confirms broad, non‐Debye relaxation processes across all compositions. The combined σ ′– σ ″ dispersion, impedance ( Z ′– Z ″) behavior, and asymmetric relaxation parameters provide clear evidence that charge transport is governed by frequency activated hopping and strong interfacial Maxwell–Wagner–Sillars polarization at PPy–CB interfaces. These enhanced dielectric and electrical properties highlight the potential of PPy/CB nanocomposites for electronic, sensing, and energy storage applications.