Preparation Of Carbon Dots Functional Composite Fibers And Study Of Their Properties

Organosilane functionalized Carbon dots(SiCDs)have excellent properties,but the simple form of existence greatly limits their application aspects.With the development of nano-science,SiCDs have attracted more and more attention from researchers.In this paper,the controllable preparation of Si02 composite fiber doped with high SiCDs content and its application are the main research goal.A series of SiCDs/SiO2 composite fibers with different content of SiCDs were prepared by adjusting the gelation time,acetic acid pH and concent of SiCDs.In addition,this paper explored the application of composite fiber in oil-water separation and oxygen sensing.The main research contents and results are as follows:(1)The controllable preparation of SiO2 xerogel nanofibers by combining sol-gel chemistry and electrospinning technology was successfully achived.The mechanism of methyltriethoxysilane(MTES)sol-gel process with different gelation time was studied in depth.The effects of a physical and chemical characteristic of MTES sol on the properties of as-prepared fibers were also analyzed.The research results show that the MTES sol prepared using MTES:ethanol:H2O in a molar ratio of 1:6:5 under acidic catalysis conditions has excellent spinnability in a long span of reaction time.With the increase of gelation time,the colloidal particle size,crosslinking degree and sol viscosity of the MTES sol gradually increased.MTES molecules gradually formed a linear macromolecular structure from the monomer under acid catalysis due to the incompletely hydrolysis of MTES,so these MTES sol had excellent spinnability.(2)The controllable preparation of SiCDs/SiO2 composite sols and their electrospun fiber were successfully realized by adjusting gelation time and acetic acid pH.The SiCDs content in SiCDs/SiO2 fibers was successfully increased to 30 wt%by optimizing the preparation parameters.The research results show that the SiCDs/SiO2 sol prepared by optimal parameters had good spinnability,and the SiCDs/SiO2 fibers prepared by the sol which viscosity was between 250-1000 cp had good morphology.The pH of acetic acid had important influence on spinnable time and crosslinking degree of the sol,and on the morphology,thermal stability and fluorescence intensity of as-prepared fibers.In addition,with the increase of the SiCDs content,the spinning time of the SiCDs/SiO2 sol becomed shorter,the hydrophobic properties of the fiber gradually increased,and the thermal stability decreased remarkably.The absolute quantum yield of SiCDs-20 fibers was as high as 102.98%.(3)SiCDs/SiO2 fibers have excellent oil-water separation properties.The results show that the fiber membrane has good and stable hydrophobic properties for various corrosive liquids.The oil-water separation efficiencies of SiCDs-10 was 98.5%,and its oil fluxs was 854 L·m2·s-1.The feasibility of the application of SiCDs/Si02 fibers in oil-water separation was fully verified by experiments,which laid a solid foundation for the next industrialization development.(4)The hydrophobic RuDPP@SiCDs/SiO2(Ru@SiCDs)xerogel nanofiber membrane with oxygen sensing was prepared by combining sol-gel and electrospinning technology.The results showed Ru@SiCDs fiber exhibited good oxygen sensitivity due to its hierarchical pore structure and its I0/I100 ratio was about 3.0 which was much higher than common polymer fiber.The fluorescence oxygen response curve of the fiber membrane had a good linear correlation,and the correlation coefficient R2 fitted by the Stern-Volmer equation and the Ratiometric method was as high as 0.995 and 0.998,respectively.The concentration and distribution of oxygen on the surface of the fiber membrane were read out directly by ratiometric imaging.Such a hydrophobic Ru@SiCDs fiber membrane with oxygen sensitive has potential application in the field of optical gas sensor.