Explosives Sensing with Bifunctional Luminescent Polymers
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: New spray-on films developed at UC San Diego have found recent application in portable devices that can quickly reveal trace amounts of nitrogen-based high explosives for forensic and counter-terrorism applications. Contaminated fingerprints, containing as little as 10 picograms of high explosive, leave dark shadows on the blue fluorescent films under ultraviolet irradiation. The security systems company RedXDefense has developed a portable kit based on the explosives ink detection technology that is gaining market acceptance. Detection relies on the use of silafluorene-containing polymers developed at UCSD in the Trogler group (http://www.rsc.org/Publishing/ChemTech/Volume/2008/07/Explosive_detection.asp). These polymers emit blue light when excited by ultraviolet radiation. Nitrogen-based explosive chemicals, such as TNT or RDX, quench the polymer luminescence by excited state electron transfer. Handling explosives can leave nanogram to microgram quantities stuck to fingers, hair, clothes, or vehicles. Even a small amount of the polymer, about one thousandth of a gram, is enough to detect explosives on a surface a half- square foot in area. This visual fluorimetric approach to explosives particulate detection at UCSD complements work being done at LLNL for colorimetric detection of high explosives through the use of a series of chemical reagents. This has been fielded as the Easy Livermore Inspection Test for Explosives (ELITE) (https://www.llnl.gov/str/Oct06/Reynolds.html). Our proposal seeks to extend and validate the UCSD fluorimetric approach using the rigorous LLNL field testing analytical protocol. A graduate student, Paul Martinez from UCSD, will be supported in his research seeking to make second generation polymers that detect peroxide explosives by a “turn on” fluorimetric sensor. This would make available sensing of an increasingly used class of improvised (homemade) explosives, which have already been fielded by terrorists in Europe and Palestine, where conventional high explosives are tightly controlled. On the fundamental research side, the work at UCSD will seek to prepare a novel bifunctional sensor polymer that incorporates “turn-off” and “turn-on” sensors for the nitrogen and peroxide classes of high explosives, respectively, in the same polymer chain. Validation on hazardous “real world” explosives will be done in collaboration with the LLNL group directed by Dr. Reynolds, and funding for support at their testing facility is requested. The impact of the research when completed would be 1) the synthesis of a novel bifunctional polymer; 2) demonstration of turn off and turn on sensing in a single polymer sensor; 3) an improved sensor for a broad class of nitrogen-based and peroxide-based high explosives that will have immediate practical applications in forensics and homeland security; 4) training of an underrepresented Ph.D. student in a area of current national need.