| The fluorescent molecules,as a new type of polyurethane chain extender,were then linked to the main chain or side chain of waterborne polyurethane through chemical reaction,and the polymer fluorescent materials needed in daily production were prepared.Initial polymer fluorescent materials are mostly obtained by blending,and they often encounter some problems,such as their heat resistance is relatively unstable,the preparation process is complicated,and the wastewater discharged from the preparation is easy to pollute the environment and harm human health.Therefore,in order to meet the market demand of environmental protection,safety and high efficiency and the needs of social and economic development,we are required to develop waterborne polyurethane fluorescent materials that are in line with the development of green economy.By inserting fluorescent micromolecules with fluorescent properties into waterborne polyurethane chains,this paper synthesized fluorescent polymers with excellent properties such as strong fluorescence,high heat resistance,good film-forming property,difficult color migration,and environmental friendliness,and realized the polymerization and water solubility of micromolecules,thus becoming an environmentally friendly polymer material.Not only can it overcome the shortcomings of traditional polymer fluorescent materials and small molecule fluorescent materials,but it can also broaden the application fields of waterborne polyurethane,such as optical devices,coatings,anti-counterfeiting and so on.The main research works are as follows:(1)By hydrothermal method,a kind of highly fluorescent hybrid silicon quantum dots(znoSiQDs)was synthesized,which was introduced into polyurethane chain as chain extender,and the waterborne polyurethane fluorescent emulsion of hybrid silicon quantum dots(znoSiQDs-WPU)was prepared by modified acetone method.This paper analyzed the structure and performance of znoSiQDs-WPU by infrared spectroscopy(FT-IR),thermogravimetric analysis(TGA)and fluorescence spectroscopy(FL),et al.Research shows that znoSiQDs has been successfully grafted into polyurethane chain,and znoSiQDs-WPU has excellent optical properties and thermal stability.At the same time,znoSiQDs-WPU can shield ultraviolet rays from 300 nm to 400 nm,and it has good application potential in the fields of optical devices,functional coatings and ultraviolet shielding.(2)A nitrogen-doped carbon dots(N-CQDs)was successfully prepared by hydrothermal method,and it was introduced into polyurethane chain as chain extender.A nitrogen-doped carbon dots waterborne polyurethane fluorescent emulsion(N-CQDs-WPU)was prepared by modified acetone.It was proved that nitrogen-doped carbon dots were successfully bonded into waterborne polyurethane chain by FT-IR,FL,XRD and UV-Vis,et al.The results show that N-CQDs-WPU has excellent film-forming property,thermal stability and optical properties.Its fluorescence intensity is reversible to temperature and has the function of shielding ultraviolet rays.It has a great application prospect in ultraviolet protection,anti-counterfeiting or other functional coatings.(3)By synthesizing a kind of 4-(diethylamino)phenylfluorone(4-DSAF),which was grafted into polyurethane chain as chain extender,4-(diethylamino)phenylfluorone waterborne polyurethane fluorescent emulsion(4-DSAF-WPU)was synthesized by modified acetone method.In this paper,Fourier transform infrared spectroscopy(FT-IR),fluorescence spectroscopy(FL),XRD and other characterization methods were used to analyze,which showed that 4-(diethylamino)phenylfluorone(4-DSAF)was successfully grafted into polyurethane chain.It is shown that 4-DSAF-WPU has excellent film-forming property,fluorescence property and thermal stability,and can emit bright red fluorescence under the irradiation of ultraviolet rays with wavelength of 365 nm,and the fluorescence intensity decreases obviously with the increase of 4-DSAF content,which is mainly caused by fluorescence quenching.At the same time,the introduction of 4-DSAF enhances the thermal stability of waterborne polyurethane.The research shows that the fluorescence intensity is reversible to temperature.The three different waterborne polyurethane fluorescent emulsions were synthesized in this paper,namely,the blue-fluorescent waterborne polyurethane emulsion of hybrid silicon quantum dots,the blue fluorescent waterborne polyurethane emulsion of nitrogen-doped carbon dots and the red fluorescent waterborne polyurethane emulsion of 4-(diethylamino)phenylfluorone.This paper studies the luminescent properties,light absorption properties and thermal stability of fluorescent emulsion.It provides a new research idea for the application and development of waterborne polyurethane fluorescent materials.Because it is a green and environmentally friendly polymer material,it has excellent film-forming properties and good optical properties.It has great potential in the fields of ultraviolet protection,functional coating,architectural coating and anti-counterfeiting.Figure [41] table [12] reference [180]... |
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