Fluorescent Polyacetylene Thin Film Sensor for Nitroaromatics

Abstract

The fluorescence from thin films of poly[1-phenyl-2-(4-trimethylsilylphenyl)ethyne] (PTMSDPA) is strongly quenched by the vapors of a variety of nitroaromatic compounds present at levels ranging from parts-per-million to parts-per-billion in air. The quenching is believed to arise because of the formation of charge-transfer complexes between the electron-poor nitroaromatic quenchers and the electron-rich poly(bis-aryl acetylene). The fluorescence quenching response rate increases as the PTMSPDA film thickness decreases (80 nm → 3 nm) and as the vapor pressure of the nitroaromatic quencher increases. These observations imply that the fluorescence quenching response rate is determined by the rate by which the nitroaromatic compound permeates the PTMSDPA film. The high permeability and large free volume of PTMSDPA are believed to enhance the properties of the material in the application as a thin-film fluorescence sensor for nitroaromatic compounds.