Facile Preparation of PANI-Sr Composite Flexible Thin Film for Ammonia Sensing at Very Low Concentration

Abstract

Conducting polymers, are still fascinating the industrial applications area since their discovery, particularly in the field of chemical sensors. For this purpose, flexible and highly sensitive based polyaniline-strontium (PANI-Sr) films were successfully prepared via a facile in-situ chemical polymerization process of aniline in presence of Sr (NO3)2 deposited on biaxially oriented polyethylene terephthalate (BOPET) flexible substrates with prior surface treatment using (3-aminopropyl) trimethoxysilane. Spectral, structural, morphological, and surface behavior characterizations were carried out using Fourier transform infrared spectroscopy (FTIR-ATR), X-ray fluorescence (XRF), raman spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and surface wettability. The electrical conductivity was measured by the usual four probes technique. Noticeably, the prepared films with Sr (NO3)2 ∼2 M have shown a highest conductivity of 0.3 S·cm−1 over the other samples. This conductivity feature has been exploited to test the sensitivity and the performances of the obtained films toward different type of gas. The PANI-Sr sensor demonstrates an outstanding selectivity and an excellent sensitivity towards the ammonia (498% response to 100 ppm) within a detection limit of 0.013 ppm, and a fast response/recovery time (1 s /42 s) toward 50 ppm at room temperature. The PANI-Sr sensor also showed a good reproducibility during five cycles. The interaction mechanism of PANI-Sr sensor film and the NH3 vapors was discussed basing on the impedance spectroscopy analysis results. The obtained results highlight the paramount role played by the strontium particle in enhancing the ammonia detection performances, when they are imbedded into PANI matrix through facile preparation process, and they emphasize their prominence over the similar study.