Point Carbon Fluorescent Silica Compound And Its Interaction With The Paper

The China has a long history and lots of cultural relics. As a special carrier of cultural information record, paper cultural relics have left a precious spiritual wealth for human history. Precious antique calligraphy and painting, orphan book manuscripts, documents and so on, have high value of research and conservation. However, with the passage of time and the changes of environmental conditions, the physical and chemical properties of these vast rare and precious paper cultural relics have changed. Paper relics have showed different degrees of "pathological changes", such as turning yellow, mildew, pulverization, brittle fracture, and serious pigment discoloration. Many precious paper cultural relics, which mostly exit in the form of orphan, once damaged, will not be able to be repaired again. In order to protect the cultural relics effectively and permanently, researchers have to obtain accurate information on the surface of the paper relics firstly. Paper acidity, as one of the most important information on the surface of paper, which can influence the physical and chemical properties of paper, is such necessary for the protection and restoration of cultural relics.Carbon dots, as a new type of carbon-based nanomaterials, have superior biocompa--tibility and optical performance. Many researchers devote their effort to synthesize the carbon dots, and a series of synthetic methods for carbon dots have been developed. Now, Carbon dots have been widely used in the field of life science, such as bioimaging, DNA and protein detection, bio-labeling, gene transfer and so on. However, the research work concerned the interaction between carbon dots and paper fibers has not been reported.This thesis consists of review part and research report.In review section, the thesis mainly introduces the preparation methods, properties and application of carbon dots. The preparation methods by top-down and bottom-up routes, surface modification by passivation treatment or doping semiconductor quantum dots and the application in the field of life analysis are mainly summarized.The research report section mainly includes the following two aspects:1. The preparation of pH-sensitive fluorescent carbon dots and its application for sensing the surface pH of the cellulose paper. The pH-sensitive fluorescent carbon dots, which were prepared with ascorbic acid by hydrothermal synthesizing route, were applied to the determination of pH on the surface of paper. The sensing performances of the carbon dots to pH on the surface of paper, the removal efficiency, interactions as well as the influence of carbon dots on the properties of paper were investigated, respectively. On the basis of the above research results, we successfully established a new method for sensing pH on the surface of paper by the in-situ and nondestructive way.2. The synthesis of Carbon dots/Silica nanocomposites and its interaction with cellulose paper.The amino-functionalized fluorescent carbon dots were firstly synthesized by using citric acid as the carbon source and PEI as passivation agent. Then, in the reverse microemulsion system, carbon dots were successfully doped in silica nanoparticles through the interaction between positively charged amino groups of carbon dots carrier and the negatively charged silanol groups of silica matrix. The stability of fluorescent performance of carbon dots was improved by the shielding effect of silica shell, which paved a new way to the application of carbon dots in the complex environment analysis. In addition, the interaction between Carbon dots/Silica nanocomposites and cellulose paper was further investigated and our results showed that this nanocomposites did not present any obviously damage effect on the surface of the paper relics.