Fiber-Optic Detection of Explosives Using Readily Available Fluorescent Polymers

A series of simple fluorescent polymers were readily synthesized by palladium-catalyzed Suzuki Coupling reactions of dibromoterephthalates containing the small methyl and large cholesteryl esters with bisboronic esters derived from alkylated fluorene and N-hexyldiphenylamine. The polymers had an inherent viscosity ranging from 0.25 to 0.74 dL/g and were characterized by spectroscopic methods. The glass transition temperatures for these polymers ranged from 90 to 104 degrees C, and the decomposition temperatures were in a range of 291-435 degrees C in nitrogen. All the polymers emit around 450-530 nm with the absolute fluorescence quantum efficiencies up to 6 1 The polymers were tested for detection of the vapor of explosive analyte (2,4-dinitrotoluene) as a thin film coated oil glass substrate and on optic-fiber tips. Explosive detection using the polymer-coated optic-fiber probe has been demonstrated to be fast and sensitive, with the fluorescence quenching efficiency reaching 49% within 25 s or 61% within the first minute.