Di-Urethane Cross-linked Poly(oxyethylene)/Siloxane Nanohybrids Doped With Eu(CF3SO3)3

Abstract

ABSTRACTAttractive sol-gel derived di-urethane cross-linked poly(oxyethylene), POE/siloxane hybrids (di-urethanesils) doped with europium triflate, Eu(CF3SO3)3 were examined by Fourier Transform mid-infrared (FT-IR), Raman (FT-Raman) and Photoluminescence spectroscopies with the main goal of elucidating the chemical environment of the cations in these materials. In these hybrids the POE chains contain about 13 oxyethylene repeat units. Samples with compositions ∞ > n ≥ 5 (where n indicates the ratio of (OCH2CH2) moieties per Eu3+ion) were investigated. The FT-IR and FT-Raman data obtained provided unequivocal evidence that the ether oxygen atoms of the polymer chains start to interact with the Eu3+ ions at n = 20. The presence of a crystalline POE/Eu(CF3SO3)3 complex was detected at n ≥ 20. Photoluminescence results demonstrated that the doped di-urethanesils studied here are room temperature (RT) efficient full-color emitters. Two distinct cation local sites were unequivocally identified at n = 200 and 20. These Eu3+ local coordination sites involve the oxygen atoms of the urethane carbonyl groups and weakly coordinated Eu3+/CF3SO3 ionic species. For the most concentrated hybrid (n=5) evidences of a third local-environment probably involving the oxygen atoms of the polymer chains was observed.