Paper-Based Probes with Visual Response to Vapors from Nitroaromatic Explosives: Polyfluorenes and Tertiary Amines

Area of Science:

• Materials Science
• Analytical Chemistry
• Polymer Science

Background:

• Nitroaromatic compounds are known fluorescence quenchers and form colored complexes.
• Paper offers potential as a substrate for macromolecular detection systems.
• Cationic polymers can be immobilized on slightly negatively charged paper surfaces.

Purpose of the Study:

• To develop paper-based sensors for nitroaromatic explosive detection.
• To investigate the use of different polymers, including polyDMAEMA and polyfluorenes, as sensing materials on paper.
• To achieve selective and visually identifiable detection of explosive vapors.

Main Methods:

• Impregnating paper strips with fluorene-phenylene copolymer, bisfluorene-based cationic polyelectrolyte, and poly(2-(dimethylamino)ethyl methacrylate) (polyDMAEMA).
• Exposing polymer-coated paper sensors to nitroaromatic vapors, including 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT).
• Observing and quantifying fluorescence quenching and visual color changes under natural light.

Main Results:

• Conjugated polymers showed non-selective fluorescence quenching with nitroaromatic vapors.
• PolyDMAEMA-coated papers exhibited a selective visual response to 2,4,6-trinitrotoluene (TNT).
• Detection was possible at low concentrations (790 ppbv TNT or 277 ppbv DNT), though exposure time was a factor.

Conclusions:

• Poly(2-(dimethylamino)ethyl methacrylate) (polyDMAEMA) coated paper offers a selective visual sensor for TNT and DNT vapors.
• Paper-based sensors provide a cost-effective and accessible platform for explosive detection.
• Further research is needed to optimize sensor performance and address limitations related to exposure time.