An oxidation-induced fluorescence turn-on approach for non-luminescent flexible polyimide films

Abstract

To develop stimuli-responsive polymers with highly comprehensive properties, sulfide-containing polyimides with relatively simple structures were designed and synthesized. The polyimides were found to have infrequent oxidation-induced fluorescence turn-on effects by being soaked in hydrogen peroxide (H₂O₂). The high contrast ratios of fluorescence quantum yield, from not being detected to up to 9.1%, were observed before and after reacting with H₂O₂. Varied emission wavelengths could be achieved by tailoring the monomer structure. This H₂O₂-sensitive phenomenon was believed to be the result of the inhibition of charge-transfer effects in the polyimide molecular structure by turning sulfide (donor) into sulfone (acceptor) in the diamine moiety. Furthermore, these tough and thermally stable polyimide films accomplished fluorescence turn-on characteristics without sacrificing their original comprehensive performance of good flexibility and transparency, indicating their potential in high-performance H₂O₂ sensors, data-security and anti-counterfeit materials.