Tritium labeled polyethyl and polypropyl siloxanes. Synthesis and self-radiolytic effects

Radioluminescent light sources with tritium labelled polymers represent an attractive technological alternative to the Beta Light sources. In this paper the alchyl and alchyl-phenyl siloxanes with application in radio-luminescent sources industry were investigated. Ethyl-1,2-T2, ethyl-1,2-T2 phenyl, propyl-2,3-T2, propyl-2,3-T2 phenyl siloxanes were synthesized by tritiation of vinyl and allyl chloro-silanes, followed by isotope dilution with SiCl4 or phenyl chloro-silanes and hydrolysis in ethyl ether solution and thermal polycondensation. The specific activities obtained were of 200 ± 20 Ci/g. The primary external effects were investigated by irradiation of unlabeled polymers using a 60 Co gamma source with an absorbed dose rate of 3 kGy/h at absorbed dose between 10 and 100 kGy. Irradiated samples were analyzed by ESR method. Self-radiolytic effects in labelled polymers were investigated by the analysis of the relative decrease of radioactivity after 365 days of storage in thin layer and at vacuum. Obtained results suggest a low stability of tritiated ethyl and propyl siloxanes. The presence of phenyl groups increases the stability, especially in the case when the phenyl and labelled alchyl groups are positioned at different Si atoms. The experimental results were compared with those obtained by modeling of self-radiolytic processes by quantum mechanical methods. (authors)