Detecting β-Radiation Using a Plastic Scintillator Containing 2,5-Diphenyloxazole-Functionalized Conjugated Polyfluorene

Plastic scintillators, as a type of radioactive radiation detectors, have shown great potential in the field of nuclear radiation detection because of their well-studied scintillating property. Although much effort has been dedicated to developing plastic scintillators with high detection efficiency, materials with excellent monitoring performance are still needed. A covalent-integration strategy was implemented in the fabrication of a series of polyvinyltoluene (PVT) scintillators containing a polyfluorene-based conjugated polymer (CP) for the detection of radioactive nuclides of Sr-90 and C-14; the scintillators feature an excellent cascade energy transfer from beta radiation to the CP. To act as an antenna for β-radiation harvesting, the fluorescent dopant 2,5-diphenyloxazole (PPO) was covalently introduced to the CP side chain. The PPO-functionalized CP was embedded in PVT to fabricate the polymer-blend scintillator, showing enhanced photomultiplier-detectable signal via efficient energy transfer. The cascade energy transfer, in which the β-radiation energy was absorbed by PVT and PPO and was finally transferred to CP, was successfully demonstrated. The scintillator showed a high detection efficiency of up to 50% under Sr-90 radiation, i.e., 30% higher efficiency than a PVT-containing simple mixture of CP and PPO, and it was also better than a conventional scintillator that contained PVT and PPO.