New insight into degradation mechanisms of conductive and thermally resistant polyaniline films

Abstract

Conductive polyaniline (PANI) coatings find application in various fields, such as electrostatic dissipation, anticorrosion coatings, actives delivery, batteries, and solar control. Improving the thermal and electrical stability of PANI coatings at high temperatures and challenging environments is of growing interest. In this study, a novel polymer blend formulation was developed by adding polyurethane (PU) and sulfonyldiphenol (SDP) to a dinonylnaphthalene sulfonic acid (DNNSA)-doped PANI matrix. Films of the PANI-PU/SDP formulation and unmodified PANI control films were prepared on ITO glass substrates using spin coating, followed by thermal treatment. Characterization of the films was performed using thermogravimetric analysis-mass spectrometry (TGA-MS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) with depth profiling. Results showed that unmodified PANI films aged at 150 °C exhibited rapid thermo-oxidative degradation, resulting in a significant loss in electrical conductivity after 24 h. The inclusion of PU and SDP remarkably improved the thermal stability of the films, maintaining desirable conductivity levels over a week. ToF-SIMS depth profiling helped identify potential degradation mechanisms and monitor changes in chemical composition throughout the film thickness. This study provides insights into the functionality, optimization, and deployment of these new film types.