Characterization and analysis of DINCH:MEH-PPV:PVC polymeric blends for application in 3D dosimetry

The use of radiation in medicine is currently one of the best sources of control and therapeutic treatments. In this context, the development of dosimeters capable of measuring, verifying and monitoring such processes in space is of great importance. This work aimed to develop a three - dimensional luminescent system that presents real - time optical response when exposed to non-ionizing radiation. To achieve this objective, a 3D system (on the order of cm³) based on poly [2-methoxy, 5- (2'-ethylhexyloxy) -β-phenylene-oxyene (MEH-PPV) was prepared in a colorless, inert and non-toxic matrix of polyvinyl chloride (PVC) and diisononyl cyclohexane-1,2-dicarboxylate plasticizer (DINCH). The MEH-PPV was chosen because of photo-oxidation effects that result in color variation when exposed to non-ionizing radiation. Thus, for the purposes of systematic evaluation of the optical response of DINCH: MEH-PPV: PVC structures, films (area ~ 1 cm²) and cylinders (diameter ~ 5 mm, height ~ 10 mm) were initially exposed to blue light (LED, λ_max = 450 nm). The material showed noticeable variation of color with the exposure time (i.e., naked eye sensitivity). The FTIR and UV-Vis spectrometry confirmed that the effect of photo-oxidation in MEH-PPV, is mainly due to the replacement of vinyl C=C by the ketone C=O bonds. The photodegradation mechanism of the MEH-PPV polymer, which results in a color change of the material from red to colorless, is an excellent response tool for the absorbed dose in real time. These results leave no doubt as to the potential of luminescent polymers for the development of three-dimensional solid systems applied to measurement and verification of a radiation field. (author)