The advancement of autonomous radiological and nuclear (RN) search to counter nuclear threats will require robust, low cost, lightweight and low power radiation sensors with neutron-gamma discrimination and superior energy resolution capabilities. To achieve this, photo detectors such as photomultiplier tubes (PMTs) or photodiodes will couple with scintillators having tailored properties. Here we show that robust plastic scintillators can be made from polymers loaded with high-Z materials, fluorescent molecules showing thermally activated delayed fluorescence (TADF). TADF-emitters can potentially harvest 100% of the excitations produced internally in response to neutron/gamma ray interactions, and represent a low-cost all-organic alternative to the use of phosphorescent or fluorescent molecules. We have developed a series of scintillators from cross-linked polymer of vinyltoluene-bismuth methacrylate (BisMet) and a light-emitting molecule - 2,4,5,6-Tetra(9H-carbazol-9-yl) isophthalonitrile (4CzIPN), displaying thermally activated delayed fluorescence (TADF). The polymerization of vinyltoluene monomer mixed with different compositions of BisMet and 1 wt.% of 4CzIPN yielded highly transparent solid polymers with no observable glass transition temperature (Tg) until the polymer's decomposition temperature. The scintillators exhibited intense green fluorescence characterized by fluorescence spectroscopy. Early experiments and Monte Carlo simulations show that these scintillators can yield good energy resolution at shapes that can be processed into embedded-system level components for autonomous RN search platforms.

Robust organic scintillators from cross-linkable bismuth compounds and thermally activated delayed fluorescent dyes

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.