Synthesis of CSA-Capped Poly (Aniline-co-Aniline-2-Sulfonic Acid) Spherical Nanoparticles for Gas-Sensor Applications

We synthesized emeraldine salts of poly(aniline-co-aniline-2-sulfonic acid) capped with camphorsulfonic acid (CSA), forming spherical nanoparticles (NPs), i.e., CSA-capped P(ANi-co-ASNi), and demonstrated their efficacy as gas sensor elements. The core-shell shaped spherical NPs exhibited an average diameter of 265 nm, with the hydrophobic CSA enabling chemical interactions with the outer surface of the positively charged P(ANi-co-ASNi) particles. These interactions facilitated stable charge transport within the copolymer chains while imparting resistance to external humidity. The synthesized CSA-capped P(ANi-co-ASNi) sensors reliably detected acetone gas at concentrations as low as 1 ppm and 1% RH water vapor at ambient temperature. These sensors also exhibited enhanced stability under various conditions, including variations in temperature, humidity, and cyclic performance, outperforming the conventional pure PANi.