Tuning the protonation and oxidation of polyaniline–zeolite composites by argon plasma treatment

Conducting polymers (CPs) like polyaniline (PANI) are considered for sensing applications due to the π -electrons in their backbone acting as doping sites for charge carriers. The conductivity of PANI is attributed to its emeraldine form, which consists of a bipolaron and polaron transition. The stability and conductivity of PANI, however, depend on the selected synthesis approach. This study investigated the feasibility of enhancing the protonation of PANI by incorporating Na-Zeolite and plasma treatment. The formation of PANI within the pores and surface of Na-Zeolite was confirmed by micrographs in SEM, and the dominance of PANI over Na-Zeolite features was confirmed in both IR and Raman spectra. The degree of oxidation, obtained by measuring the IR absorbance ratio of the deconvoluted Q and B rings in the 1546 cm − 1 and 1469 cm − 1 , respectively, confirmed the emeraldine form of PANI in the PANI/Na-Zeolite (PNZ) composites with a degree of oxidation range of 44.68 ± 0.35 % to 52.16 ± 0.93%. After plasma treatment, the degrees of oxidation of PANI in the PNZ composites increased to a range of 57.49 ± 0.38 % to 59.16 ± 0.14 %. This increase was attributed to the protonation of PANI, which is primarily caused by the e − , Ar + ions, and the generated reactive species like H + ions. The transformation of PANI, in the plasma-treated PNZ composite, into the emeraldine salt was confirmed by the presence of polaron (shoulder at 430 nm) and bipolaron (600 to 800 nm absorption band) cationic transitions in the UV–Vis spectra. The increased cationic characteristics of the plasma-treated PNZ composite were then evaluated for its biosensing ability using glucose as the test analyte. The resulting LOD range (2.12 ± 0.66 to 3.59 ± 0.009 mM) of plasma-treated PNZ composites is lower compared to both the standard and diabetic glucose level ranges of 3.9 to 5.6 mM and > 7.0 mM, respectively. The results of this study showed the potential of plasma-treated PNZ composite for biosensing applications.