Polypyrrole Nanofibrous Aerogel for Pressure Sensing and Anionic Contaminant Remediation

We report the fabrication of a conductive nanofibrous aerogel (NFA) by coating polypyrrole (PPy) onto a mechanically resilient polyacrylonitrile/polyvinylpyrrolidone (PAN/PVP) NFA framework via low-temperature oxidative polymerization. The PPy forms a conformal layer on individual nanofibers, generating continuous three-dimensional conductive pathways. The resulting hybrid combines the robust framework of the NFA with the conductivity and chemistry of PPy, enabling stable pressure sensing and effective sorption of anionic contaminants from water. Systematic variation of the oxidant-to-monomer ratio and polymerization time reveals how PPy coating morphology and loading influence the sensing and adsorption performance. Optimized samples exhibit a sensitivity of 5 kPa^{- 1} and a gauge factor of 0.32 within 0%-5% strain for low-pressure piezoresistive sensing. When integrated into a wearable format, the NFA enables real-time motion detection, while tolerating large compressive strains and maintaining shape recoverability up to 70% under repeated loading. It also exhibits strong affinity for metanil yellow, an azo dye commonly found in industrial effluents that adversely impacts aquatic ecosystems. Removal efficiencies are maintained across varying pHs (3-9), with maximum adsorption of ∼98 observed at pH 5. Adsorption is reversible, with comparable uptake sustained over multiple cycles. Overall, the PPy-coated NFA establishes a tunable, multifunctional platform for both pressure sensing and water remediation.