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Making our World Safer: HKUST Researchers Develop New Chemosensor for Explosive Detection that Doubles as Optical Limiter

In this ultra security-conscious age, Prof Benzhong Tang, Chair Professor of Chemistry at HKUST and his research team, after years of painstaking research, have achieved a major breakthrough in his search for new polymerization reactions and new functional materials that are the answers to the prayers of security authorities. These groundbreaking discoveries are detailed in Polymer Chemistry, a prestigious journal of the Royal Society of Chemistry.

In layman terms, what the research team led by Prof Tang has developed is new polymer material that makes for a promising fluorescent chemosensor for explosives detection. The idea behind this is that whereas the compound is non-emissive or weakly fluorescent in solution, it becomes strong emitter when aggregated in poor solvents and in the solid state. The polymer exhibits high thermal stability even in temperature reaching 400°C in nitrogen and air. That said, the emission of the polymer in the solution and aggregated states can be quenched efficiently by picric acid, and the explosives TNT and DNT with large quenching constants.

On top of these breathtaking discoveries, the research team also devised a novel polymerization approach to upgrade the structure of organic light emitting materials to three dimensions, rendering it a more nimble sensor for explosives. The agent is applicable in security systems, screening for explosives under any circumstances, thus heightening the detection capability of security systems. "In the past, the explosives can go undiscovered once wrapped up in plastics." Prof Tang said, "With our newly-invented technique, the loopholes of the existing screening mechanisms can be plugged with ease."

Prof Tang pointed out that the polymer can also be used as an optical limiter. Taking on nonlinear optical properties, it can extenuate the transmittance at an ideal level, which is to offer high transmittance at low inputs but low transmittance at high laser doses. The optical limiting property, coupled with its high thermal stability and good processability, make the polymer a promising candidate material for high-tech applications.

Amongst Prof Tang's research team members were Dr Rongrong Hu, Dr Jacky W Y Lam and Dr Jianzhao Liu. Also helping with the research were Prof Matthew M F Yuen of the Department of Mechanical Engineering, Dr Herman H Y Sung and Prof Ian D Williams of the Department of Chemistry, as well as Prof Zhounan Yue and Prof Kam Sing Wong of the Department of Physics.