Gas Sensing With Polymeric Materials: Improved Sensitivity and Selectivity for Acetaldehyde and Formaldehyde

Abstract

Selective detection of volatile organic compounds (VOCs) remains a critical challenge in environmental monitoring and industrial safety. This study investigates the sensitivity and selectivity of four pristine polymeric backbones—polyaniline (PANI), polypyrrole (PPy), polyvinylpyrrolidone (PVP), and polythiophene (PTh)—for the detection of acetaldehyde (Ac) and formaldehyde (F). Among these, PANI demonstrated significant sensitivity to both gases, making it a promising candidate for detecting F. Conversely, PPy and PVP exhibited pronounced sensitivity and selectivity for Ac, making them suitable for applications requiring selective Ac sensing. PTh, with negligible sorption of both analytes, can serve as a material to indicate a sensor baseline. Modifications to the PANI backbone, including poly(o-anisidine) (POANI), poly(N-methyl aniline) (PNMA), and poly(2,5-dimethyl aniline) (P25DMA), were also evaluated. While these derivatives improved Ac sensitivity, they reduced F sensitivity due to altered electrostatic interactions. Among these, P25DMA displayed a relatively higher selectivity for F, although it still needs further refinements. Binary and ternary gas mixture analyses were conducted to simulate real-world scenarios with multiple VOCs, revealing PPy and PVP as optimal materials for Ac detection, and P25DMA as a good material for detection of F. Mechanistic insights indicate that electrostatic interactions and polymer morphology significantly influence sorption behavior. This study underscores the potential of tailored polymeric materials for specific gas sensing applications and reports notable selectivity achievements for gas sensing polymers for detecting structurally and functionally diverse analytes.