Influence of in-situ reaction on luminescent properties of samarium-complex/hydrogenated acrylonitrile-butadiene composites

In this work, acrylato(1,10-phenanthroline)bis(2-thenoytrifluoroacetonato) samarium(III) [Sm(TTA)2(AA)(Phen)] [Sm-AAPhen; TTA = 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, AA = acrylic acid, Phen = 1,10-phenanthroline] has been synthesized for the first time, which combines the good fluorescence property of Sm(TTA)3(Phen) and the reactivity of acrylic acid with radicals. The uncured composites were prepared by adding different amounts of the Sm(TTA)3(Phen) complex and a certain amount of peroxide into hydrogenated acrylonitrile-butadiene rubber (HNBR). The cured composites were prepared by vulcanizing the uncured composites at 160 °C under a pressure of 15 MPa for 20 min. Fourier Transform Infrared (FTIR) spectra show that the intensity of peaks assigned to reactive CC bond decreases after the curing process, verifying that the in-situ reaction (including polymerization and grafting) of Sm-AAPhen initiated by peroxide radicals took place during the cross-linking of the HNBR matrix. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) observations show that the dispersion dimension of the cured composite is far finer than that of the uncured composite. Wide-angle X-ray diffraction (WAXD) testing shows that the crystallinity of Sm-AAPhen in the composites was absent dramatically after the curing process, implying that most of crystalline Sm-AAPhen complex took part in the in-situ reaction and formed the non-crystalline poly(Sm-AAPhen). The dispersion phase of cured Sm-AAPhen/HNBR composites is composed of completely almost nanometer-sized poly(Sm-AAPhen) and few residual Sm-AAPhen particles with significantly reduced dimensions. The fluorescent intensity, lifetime and quantum yields of the cured composite are much higher than that of the uncured one with the same Sm-AAPhen content due to the in-situ reaction.