Construction And Application Of Composite Fluorescence Materials Based On Cellulose And Phosphor

With the progress of the society and technology, resources and environment have become increasingly important in the global sustainable development. Because of the decline of oil and coal reserves, and the more attention on the problem of the environment pollution, it is preferable to exploit and apply the renewable resources. Cellulose, a kind of the most abundant renewable resource in the world, is synthesized by photosynthesis reached 5000 tons every year. In other words, cellulose is the inexhaustible and renewable organic resource. Besides, cellulose possessing high molecular weight and crystallinity,outstanding biodegradability, excellent biocompatibility and good mechanical properties, is one of the most promising materials. Composite fluorescent materials based on cellulose are a type of new functional materials through physical or chemical method combining cellulose and luminescent materials, which not only have the characteristics of natural polymer, but also give its unique luminescence properties. At present, the study on cellulose composite fluorescent materials are in the initial stage, and explores the different types of cellulose fluorescent materials with special application value have attracted the extensive attention of researchers. In this work, different composite luminescent materials based on cellulose have been synthesized, and the structure, properties and applications of products are in depth studied. The main contents include the following three points:Firstly, the cellulose/Sr2Si5N8: Eu2+ films have been synthesized through the dissolution of Na OH/Urea solution via a simple physics method. In the experiment, the cross sectionand free surface of the hybrid films are analyzed, suggesting that the strong interaction between the cellulose solution and Sr2Si5N8: Eu2+ particles. At the same time, with the addition of Sr2Si5N8: Eu2+, compared to the pure cellulose film, the hybrid films show more excellent mechanical properties. In addition, from the point on the application in sunlight conversion, the hybrid film can effectively absorb ultraviolet light(below 400 nm), and then convert it to red light(600-700 nm).Secondly, the combination method of the cellulose and the carbon dots has been studied in the solution of N-methylmorpholine-N-oxide(NMMO). From the analysis of Fourier transform infrared spectrum, it confirms that a part of the hydroxyls are gradually oxidized to carboxyl during the dissolution of cellulose in NMMO solution firstly, and then they are reacted to the amide groups on the surface of CDs, leading to the carbon-nitrogen bond.Moreover, the combination mechanization comes up. Then, the fluorescence properties of the composite are studied with the change of temperature, indicating that the emission intensity decreased nearly linearly with increasing temperature from 200 to 420 K,presenting a fluorescent sensing capacity for temperature. And the correlation coefficient is calculated, about 0.99, which shows the great potential in temperature sensing.Finally, the transparent sunlight conversion films based on carboxymethyl cellulose(CMC) and carbon dots(CDs) have been developed for the first time through dispersion of CDs in CMC aqueous solution. From the analysis of Fourier transform infrared spectrum,the hydrogen bonds interaction is formed between the CMC solution and the CDs, whose surfaces are containing lots of polar groups. Moreover, the results from mechanical property test confirm that the strong interaction is formed in the hybrid films. At the same time, a series of spectroscopic properties are tested. And it presents that the composite films can efficiently convert ultraviolet light to blue light free from the absorption of visible light,expected to apply in the field of agricultural planting for sunlight conversion.