MWCNTs/PMMA/PS composites functionalized PANI: electrical characterization and sensing performance for ammonia detection in a humid environment

Abstract This work aims to develop stable and reliable sensor films based on polyaniline (PANI) composites able to detect ammonia in a humid environment. For the preparation, PANI is hosted in poly(methyl methacrylate)(PMMA)/polystyrene (PS) blends matrix and to optimize the electrical properties, multi-walled carbon nanotubes (MWCNTs) are added into the matrix. The preparation method alternating heating and ultrasonic treatment leads to good dispersion and ensure stable films. The materials are characterized by infrared (IR) spectroscopy, scanning electron microscopy (SEM) and electrical characterizations. The temperature-dependent electrical measurement showed that PANI governed the electrical properties in the composites. The resistive sensors based on such composites are tested for ammonia detection and the composite based especially on PANI/PMMA/PS/MWCNTs shows the best sensor performances, with a linear sensitivity in the 5–20 ppm range, a limit of detection (LOD) averaging 830 ppb and response and recovery time estimated to 270 and 630 s, respectively. Furthermore, it presents repeatable responses and very good stability in a humid environment as well as long-term stability. The preparation way is an essential point to reach these performances that result from a synergetic contribution of all elements.