Fabrication And Properties Of Luminescent Composite Films Based On Quantum Dots

The increasingly serious environmental pollution has affected the living quality and threated the heath of people.Therefore,rapid and sensitive detection methods of pollutants have attracted wide attention.Quantum dots?QDs?have been widely used in material detection with the unique size-dependence and remarkable photoluminescence?PL?properties.At present,most QDs for detection are dispersed in solvent with higher sensitivity but inconvenient transportation and storage which limits its application.Luminescent QDs films have the advantages of convenient transportation and storage,but some disadvantages still exist,such as the decreased PL intensity and lower sensitivity in detection.So it is being of great research significance for environment analysis to develop a kind of luminescent film with higher stability,remarkable PL intensity and higher sensitivity in detection based on QDs.In this thesis,QDs/polymer luminescent films with excellent PL properties were prepared through the electrospinning technology and dip-coating method.And the application of luminescent films in detection was explored.The main contents are as follows:?1?Branched polyethyleneimine?PEI?,a polymer with a large number of amino groups,was chosen as the surface modifier to change CdSe/CdxZn1-xS QDs synthesized in organic phase to QDs-PEI by ligands exchange.And then electrospinning technique was used to prepare?QDs-PEI?/PA6 fluorescent composite films,which PL intensity was turned by different additive content of QDs.It was found that the composite film has great sensitivity for 2,4,6trinitrophenol?TNP?.The detecting limit by naked eyes was 100 ng/mL.At the concentration of 50-100 ng/mL,it could realize the sensitive and quantitative determination of TNP by the luminescent?QDs-PEI?/PA6 film.?2?Nylon 6?PA6?fibrous films were prepared by electrospinning technology and then dip-coated with QDs to fabricate the luminescent composite films.The luminescent films not only have stable PL properties,but also are easy access to the detected samples because QDs are combined to the surface of nanofibers,not embedded in the interior.It was found that the composite film has great sensitivity for Cu²⁺and the detection limit under naked eyes was 80?M.At the concentration of 10-150?M,it could realize the sensitive and quantitative determination of Cu²⁺by the luminescent PA6@QDs film.?3?QDs_g/PVDF film with green luminescence was prepared by CdSe/Cd_x Zn_1-x-x S QDs?QDs_g?and PVDF by electrospinning technique.Then the?QDsg/PVDF?@QDsr dual fluorescent composite film was prepared by combining composite film with CdSe/CdS/ZnS QDs?QDsr?by dip-coating method.It was showed that the composite film has great sensitivity for Cu²⁺with the decrease of red luminescence while the PL intensity of green luminescence was nearly unchanged.The detection limit under naked eyes was 30?M.At the concentration of 10-100?M,it could realize the sensitive and quantitative determination of Cu²⁺by the luminescent?QDs_g/PVDF?@QDs_r.