• PDF / 669,722 Bytes
• 8 Pages / 595.276 x 790.866 pts Page_size
• 2 Downloads / 189 Views

DOWNLOAD

REPORT

---

Thermal behavior of the highly luminescent poly(3-hydroxybutyrate):Eu(tta)3(H2O)2 red-emissive complex D. F. Parra • P. L. Forster • R. Łyszczek A. Ostasz • A. B. Lugao • Z. Rza˛czyn´ska

•

Received: 18 September 2012 / Accepted: 19 February 2013 Ó Akade´miai Kiado´, Budapest, Hungary 2013

Abstract The aim of this study has been to gain a fundamental understanding of the mechanisms governing thermal degradation of luminescent poly(3-hydroxybutyrate) (PHB). PHB was doped with diaquatris(thenoyltrifluoroacetonate) europium(III) complex, [Eu(tta)3(H2O)2], and different luminescent systems were obtained. The thermal-stability of the luminescent films was discussed and the products of decomposition were analyzed. Thermal degradation of PHB:Eu(tta)3x % systems (x = 0, 1, 5, 10, and 15 %) was elucidated by means of thermogravimetric analysis (TG), the thermal-stability decreases with the increase of europium complex concentration. The PHB polymer decomposed with evolution of carbon dioxide and 2-butenoic acid molecules. The TG–FTIR results, of the gaseous degradation products of PHB in nitrogen atmosphere, indicated that the polymer is stable at temperatures up to 200 °C. Polymer matrix at concentrations above 5 % decomposed with evolution of water molecules among the other gaseous products, which implied the presence of a hydrated complex in the system. The luminescent films showed more flexibility due to a loss in crystallinity, which suggested a potential usefulness in technical applications.

D. F. Parra (&)  P. L. Forster  A. B. Lugao Chemistry and Environmental Centre, Energy and Nuclear Research Institute, National Nuclear Energy Commission; IPEN/CNEN-SP, Av. Prof. Lineu Prestes, 2242, Sa˜o Paulo, SP 05508-000, Brazil e-mail: [email protected] R. Łyszczek  A. Ostasz  Z. Rza˛czyn´ska Department of General and Coordination Chemistry, The Faculty of Chemistry, Maria Curie-Skłodowska University, 20-031 Lublin, Poland

Keywords Lanthanides  Poly(3-hydroxybutyrate)  Thenoyltrifluoroacetonate  Thermal behavior

Introduction The lanthanide b-diketonates are widely used in the development of luminescent materials due to monochromatic emission as one of their intrinsic properties. The narrow emission bands arising from the 4f-transitions and long lifetimes make these ions unique among the luminescent coordination compounds [1]. One of the most studied lanthanide b-diketonates is the precursor complex diaquatris(tenoytrifluoroacetonate)europium(III) [Eu(tta)3(H2O)2]. For the Eu3? complexes, energy is primarily transferred from the ligand triplet to the 5D0 level leading to luminescent transitions to the ground state manifold 7 FJ (J = 0–4) which are observed in the red spectral region. The most intense transition of Eu3? is the 5D0 ? 7F2, corresponding to a red emission band at 613 nm [2]. The high luminescence is due to the efficient energy transfer via the triplet state (T) from the tta ligand to the emitter 5D0 level of the Eu3? ion. The tta- anion acts as an excellent bidentate chelate which protects the lanthanide