Improved Electrical and Thermal Aging Properties of DBSA-Doped PANI Using MWCNT and GO

Electrical conductivity deterioration of polyaniline (PANI) at elevated temperatures has limited its applications for commercial usages. In this study we endeavored to improve the thermal aging resistance of PANI and its conductivity stability at elevated temperatures using a high molecular weight dopant, dodecylbenzenesulfonic acid (DBSA), along with the addition of carbon-based nanoparticles. DBSA-doped PANI (DBSA-PANI) and its nanocomposites with graphene oxide (PANI/GO) and multi-walled carbon nanotube (PANI/MWCNT) were prepared through in situ polymerization. The samples were aged at 90°C up to 1000 h and characterized by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), scanning electron microscopy (SEM), and electrical conductivity measurements. It was observed that electrical conductivity deteriorates more rapidly in DBSA-PANI than in GO and MWCNT nanocomposites. The FTIR results confirmed a strong retention of DBSA groups in the nanocomposites after aging, but not for DBSA-PANI. This showed more stability of DBSA dopant in PANI/GO and PANI/CNT. The characteristic time (τ), as a criterion for thermal stability, was found to be 91, 172, and 295 h for DBSA-PANI, PANI/MWCNT, and PANI/GO, respectively. It was suggested that the retardation of the de-doping process is the major reason for the higher τ value and more electrical conductivity stability of PANI/GO. The obtained thermal stability for the electrical conductivity of DBSA doped PANI/GO nanocomposites was nearly 30 times higher than that of HCl-doped PANI.