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Abstract: A composite from a broad bandgap polymer, poly(phenylene ethylene) (PPE), and nano-sized TiO2 particles was found to be able to sense 2,4,6-trinitrotoluene (TNT) for TNT sensor. Fluorescence quenching induced by charge transfer from PPE to nano-sized TiO2 was observed in toluene solution. At high TiO2 composition, a strong exciplex band occurred at 550nm. Under prolonged light irradiation at 400nm, unusual fluorescence gains took place at 460nm, companied with a very small change in the UV–vis absorbance. After 30min light irradiation, the fluorescence at 460nm reached a maximum, but the peak at 550nm disappeared. This composite showed amplified sensor response to TNT compared to the pristine PPE film, which can be potentially used as sensing material for detecting TNT based explosives. [Copyright &y& Elsevier]

Abstract: Three different poly{9,9-bis[6′(–NHBoc, –NH3 + and –NH2)hexyl]fluorene}s (PF-NHBoc, PF-NH3 + and PF-NH2) have been synthesized and characterized. Both UV–Vis and fluorescence spectroscopic results supported the interaction between the polyfluorenes and Methamphetamine Hydrochloride (MAPA) was derived from the different terminals of hexyl side chains. Among the three polyfluorenes, PF-NH2 exhibited the best sensory response to Methamphetamine Hydrochloride (MAPA) in THF arising from its –NH2 terminals. The fluorescence of PF-NH2 was immediately quenched once the MAPA was added, and the detection limit of MAPA was determined to be ∼25ng/mL. Fluorescence quenching experiments of PF-NH2 by NH4Cl and other metal ions confirmed that electrostatic interaction should make contributions to the quenching behavior, in addition, upward non-linear curvature and much higher quenching constant (K sv) in the Stern–Volmer plots for MAPA suggested some other interactions such as hydrophobic or/and hydrogen-bonding interactions dominated the analyte-induced aggregation, and such hydrophobic interaction was responsible for the sensitive selectivity. The fluorescent quenching experiments upon adding other drugs such as Pethidine Hydrochloride (PTD) and Ephedrine Hydrochloride (EPD) confirmed such selectivity, especially under the high concentration of the Stern–Volmer plots. The high sensitivity, selectivity, and its simple and fast character, made it a new and effective way for drug detection. [ABSTRACT FROM AUTHOR]

We have first demonstrated that a random laser action generated by a hybrid film composed of a semiconducting organic polymer (SOP) and TiO(2) nanoparticles can be used to detect 2,4,6-trinitrotoluene (TNT) vapors. The hybrid film was fabricated by spin-casting SOP solution dispersed with nanosized TiO(2) particles on quartz glass. The SOP in the hybrid film functioned as both the gain medium and the sensory transducer. A random lasing action was observed with a certain pump power when the size (diameter of 50 nm) and concentration (8.9 x 10(12)/cm(3)) of TiO(2) nanoparticles were optimized. Measurements of fluorescence quenching behavior of the hybrid film in TNT vapor atmosphere (10 ppb) showed that attenuated lasing in optically pumped hybrid film displayed a sensitivity to vapors of explosives more than 20 times higher than was observed from spontaneous emission. This phenomenon has been explained with the four-level laser model. Since the sensory transducer used in the hybrid polymer/nanoparticles system could be replaced by other functional materials, the concept developed could be extended to more general domains of chemical or environment detection.