Recyclable Polymeric Thin Films and Water-Soluble Polymeric Probes for the Colorimetric/Fluorometric Sensors in Solution and Vapor Phase

Abstract

We developed a thin polymeric probe for the vapor-phase sequential colorimetric detection of a nerve agent mimic and ammonia with high selectivity and sub-ppm sensitivity. The free-radical polymerization (FRP) of N-(4-benzoylphenyl)acrylamide (BPAm), N,N-dimethylacrylamide (DMA), and (E)-2-(methyl(4-(pyridine-4yldiazenyl)phenyl)amino)ethyl acrylate (MPDEA, M1) were copolymerized to yield [p(BPAm-co-DMA-co- MPDEA)], herein P1. P1 exhibited selective sensing properties toward a mimic of the nerve agent, diethyl chlorophosphate (DCP), in the pure aqueous media. The pyridine groups of P1 was quaternized into quaternary ammonium salt upon the addition of DCP, accompanied by the color change from yellow to pink due to the enhancement of the intramolecular charge transfer (ICT) effect. The in situ generated quaternized P1, herein P2, after DCP sensing was used to detect ammonia selectively via dequaternization in the aqueous media, reverting the color of the solution from pink back to its original color, yellow. The surface-immobilized P1 film was prepared and employed for the vapor-phase detection of DCP, demonstrating that DCP as low as 2 ppm was detectable. In the film system, the pyridine groups of P1 were quaternized with DCP due to the absence of water, upon the addition of DCP vapor, accompanied by a color change from yellow to red. Ammonia vapor was also successfully detected by P2 film via ammonia-triggered removal of the quaternized phosphates. The entire system is reversible due to alternating exposure of this film to DCP and ammonia resulted in the corresponding color changes. While the vapor-phase sequential colorimetric detection of DCP and ammonia was repeated over five cycles, this polymeric film has been recycled. |An important reactive oxygen species (ROS), hydrogen peroxide (H2O2), plays a significant role in many biological systems. Here, a new water-soluble polymeric probe modified with pyrene and boronic acid has been designed and synthesized for H2O2 detection. Glycidyl methacrylate (GMA) and N,N-dimethylacrylamide (DMA) copolymerized by reversible addition-fragmentation chain-transfer (RAFT) polymerization to yield poly(glycidyl methacrylate-co-dimethylacrylamide) [p(GMA-co-DMA)](P1). The subsequent ring-opening reaction between secondary amine of (3-((pyren-1-ylmethyl)amino)phenyl)boronic acid with the epoxide unit of P1 yielded P2. In the presence of H2O2, the pyrene-boronic acid (Py-BA) group can transform into green fluorescent by changing boronic acid into the phenol group. Furthermore, the emission color of P2 change in a different pH and the sensing just leaning by a certain pH range. The compound exhibited an interesting fluorescence change with a quenched emission intensity at low pH but enhanced emission intensity at high pH unlike the fluorescent chemosensors using a normal PET process. This system has d-PET fluorescence transduction (PET, photoinduced electron transfer with fluorophore as the electron donor of the electron transfer). Given certain pH range H2O2 detection abilities, this polymeric probe promotes the development of new insights for stimuli-responsive water-soluble polymers with fluorescence sensing behaviors.