Preparation And Fluorescence Properties Of Noble Metal-rare Earth Organic Complex/Polymer Composite Fibers

The surface plasmon resonance(SPR)of noble metal nanoparticles is a very important optical property,which applied in optics,sensing and detection.It has been a hotspot since the 1990s.Many researches showed that the photoluminescence intensity of the fluorescent molecules were higher than that of the free state when the fluorescent molecules are placed near the noble metal nanostructured materials.Metal-enhanced fluorescent(MEF)noble metal nanostructures can significantly improve the efficiency of rare earth organic complexes,and it has a good application prospect in the field of high-sensitivity fluorescence detection.In this thesis,we prepared noble metal nanoparticles with different diameters.Furthermore,the core-shell nanofibers were prepared by electrospinning.The core fiber was composed of Tb-complex and PVP.The shell fiber was composed of noble metal nanoparticles and PVP.The objective is to investigate the influence of different diameters of Ag-NPs and Au-NPs on the fluorescence properties of Tb-complex.The main contents are as follows:(1)Nanoparticles(Ag-NPs)with different particle sizes were synthesized by two different methods.PVP/Tb-complex//PVP/Ag-NPs coaxial fibers were fabricated by coaxial electrospinning technology.The influence of different sizes of Ag-NPs on fluorescence properties of PVP/Tb-complex//PVP/Ag-NPs coaxial fibers was investigated.Silver nanoparticles(Ag-NPs)with different morphologies can be prepared by stepwise seed growth method.The silver nanoparticles with different particle sizes in the range of 30-120nm were prepared.The coaxial structure of nanofibers with the same matrix was prepared by electrospinning.The diameter distribution of these fibers was narrow.The diameter of these fibers was in the range of(260-350)±20nm.Fibers were smaller in diameter by introducing silver nanoparticles(Ag-NPs)to the nanofibers.The fluorescence spectra,fluorescence lifetime and quantum efficiency of the fluorescent fibers were measured.The fluorescence intensity,the quantum efficiency increased with the increase of the particle size of the nanoparticles,but its fluorescence lifetime became smaller.(2)The spherical gold nanoparticles(Au-NPs)with different morphologies and narrow particle size distribution were prepared by the classical reduction method(Frens method).Au-NPs had a particle size ranging from 20nm to 140nm.The optimal synthetic temperature was 75?.Although there was a small amount of aggregates for gold nanoparticles,no large agglomeration appeared.PVP/Tb-complex//PVA/Au-NPs fluorescent core-shell nanofiber was prepared by coaxial electrospinning technology.The influence of different sizes of Au-NPs on fluorescence properties of PVP/Tb-complex//PVA/Ag-NPs coaxial fibers was investigated.The results showed that shell fiber diameter of the prepared fluorescent fiber was 170±20 nm and the core one was 110±20 nm.The fluorescence intensity and quantum efficiency of the fiber increased with the increase of the particle size of the nanoparticles.Compared with the fibers without Au-NPs,the fluorescence intensity of fibers with Au-NPs increased by five times and quantum efficiency was improved by two times;also,the fluorescence life becomes smaller.