Caracterização de materiais luminescentes : estudo de blendas poliméricas PC/PMMA dopadas com complexos de terras-raras e compósitos de copolímeros acrílicos PEGDA/TEGDMA com nanopartículas de ZnO

Abstract

Many areas of science have recently shown a growing interest in developing methods for obtaining new materials emitting electromagnetic radiation in the UV /VIS region based on electronic transitions of metal ions using different polymeric materials as hosts. In this thesis, the synthesis, production and characterization of photoluminescent copolymer materials obtained from two different doping processes are presented: (1) using organic ß-diketonate complexes of rare earths and (2) by the in situ reduction of zinc oxide nanoparticles. Initially, the methods are described for the production of films of blends with different mass fractions between bisphenol-A polycarbonate (PC) and poly (methyl methacrylate) (PMMA) doped with lanthanide (III) acetylacetonate complexes [Ln(ACAC)3; Ln = Er, Tb, Dy, I] and europium (III) thenoyltrifluoroacetonate [Eu(TTA)3], and steps to obtain zinc oxide (ZnO) nanoparticles grafted on acrylic copolymer matrix of polyethylene glycol diacrylate (PEGDA) and triethylene glycol dimethacrylate (TEGDMA) from the in situ reduction of precursor zinc thenoyltrifluoroacetonate [Zn(HTTA)2] in hydrazine reflux system. Pure and doped polymer films have high transparency and were characterized by various physico-chemical techniques, such as X-ray diffractrometry (XRD), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Photoacoustic Spectroscopy (PAS), Infrared Spectroscopy (FTIR), Photoluminescence spectroscopy (PL) and Time Resolved Fluorescence (TRF). The analysis of FTIR verified the synergetic effect system PC/PMMA and PEGDA/TEGDMA, and the incorporation of appropriate dopants. From the thermal analysis, we can note an apparent miscibility between the acrylic copolymers and blends, as well as increased thermal stability of the host due to the incorporation of the dopant. XRD analysis verified the formation of hexagonal wurtzite structure of ZnO nanoparticles without affecting the crystallinity of the polymer matrix. Studies by PAS spectroscopy, PL and FRT showed that the dopants were effectively incorporated into polymer matrices, with electronic transitions of metal ions Ln3+ and Zn2+, suggesting that the polymer matrices act as an sensitizer.