Enhancement of electrical conductivity in polypyrrole–carbon black nanocomposites synthesized via UV irradiation at low filler loading below the percolation threshold

Carbon black (CB)-doped Polypyrrole (PPy) composites containing 3 wt.%, 6 wt.%, and 8 wt.% CB were synthesized via UV-assisted in situ polymerization in 1, 2-dichlorobenzene (o-DCB) to investigate electrical conductivity enhancement at low filler loading in the sub-percolation regime.UV irradiation enabled controlled polymer growth and CB dispersion, promoting interfacial interactions within the PPy matrix. UV–visible spectroscopy showed a red shifted π–π* transition (∼300 nm) and enhanced visible absorption, indicating charge delocalization. FTIR and Raman analyses confirmed PPy/CB interfacial coupling and doping induced structural modifications. SEM analysis revealed morphological modification of the PPy matrix with carbon black incorporation, accompanied by changes in aggregation behavior and structural heterogeneity at higher CB loadings. Thermogravimetric analysis demonstrated improved thermal stability due to the barrier effect of dispersed CB particles. Electrical measurements using two probe V–I characteristics (−50 to +50 V) showed an increase in conductivity from 4.61 × 10 −7 to 9.52 × 10 −7 S·cm −1 with increasing CB content, despite remaining below the percolation threshold. These results highlight UV assisted synthesis as an effective approach for developing multifunctional PPy/CB nanocomposites for antistatic coatings, resistive sensing materials, and low-leakage flexible electronic systems.