Preparation And Coloration Properties Of The Structurally Colored Fiber Based On Photonic Crystals

Many materials in nature, such as opal, butterfly wings and peacock feathers, show the unique and brilliant colors. The color called "structural color" depends on the interaction of light with periodic surface of nano-structures, and the surface structure is named for photonic crystals. When light waves are modulated by periodic structures, photonic band gap will also appear. If energy could not land in a photonic band gap, it will not be able to continue to spread. Generally speaking, the color of the reflected light will change with the gap in different positions, so there are bright colors. As we all know, various important problems have been discovered in the process of coloration, including an increase in the amount of environmental pollution by the dye industry. Ways of utilizing strong structural color effects may be explored to solve this problem.To achieve the above ideas, two important processes must be studied, one is the preparation of structural colored dyes similar to the materials in the nature; the other is how to efficiently combine these with fiber or fabric combination, and design a fiber dyeing process.In this thesis, in order to prepare the structurally colored fiber with a rapid self-assmbled speed and good optical properties, SiO2PMMA, Fe3O4@C, ZnO and ZnS spheres have been prepared through the stober method, emulsion polymerization, solvothermal and coprecipitation method, respectively. The capillary force, electric field force and magnetic field force have been employed to assemble the colloidal spheres for photonic crystals on the fiber. The application of structurally colored fiber in the field of color sensor is also explored.Generally, traditional gravity sedimentation is employed for preparation of the structurally colored films on the plane surface. However, this method shows slow deposition rate and time-consuming, which greatly reduce the efficiency of preparation of structural color. Especially it is not applicable for the cuving surface of the fiber. In the open space, three dimensional photonic crystals usually show a lot of surface defects prepared by thermal evaporation self-assembly method.In second chapter, structurally colored fiber was fabricated by an isothermal heating evaporation-induced self-assembly method.Under ambient white light illumination, the fibers appear colored due to optical reflectance, which is determined by the lattice constants of the photonic crystals. SiO2with180nm,215nm and240nm in diameter were prepared by the stober method. The colloidal spheres show good monodispersity and massive surface charges, which can be dispersed in water and ethanol. By adjusting the thermal evaporation temperature and the ratio in mixed solvents, colloidal crystal layers are tunable from monolayer to multilayer. SiO2colloidal spheres exhibit a face-centered cubic structure on the surface of the fiber with a long-range order. Through the fiber spectroscopy and optical microscope test, structure color fiber displays structural colors from473nm to528nm.Due to the lack of flexibility of glass fiber, it is limited as a colored fiber in the practical application, while the polymer fiber can overcome this disadvantage. In the third chapter, SiO2and PMMA spheres were assembled on nylon (PA) fiber by the thermal evaporation method in micro-space. The fiber displays the diffraction color in natural light. And on the basis of abovementioned researches, we explore the response characteristics of fiber to the solvent with different concentrations. The study found the fiber shows red, blue, green color with reflected spectra for493nm,534nm,682nm, respectively (corresponding colloidal spheres size:215nm,240nm,295nm). The response characteristics on PMMA colloidal spheres assembled PA fiber to the ethanol solution show that spectral reflectance peaks shift gradually from521nm to566nm with the increase of ethanol content. The fiber can be as a naked eye sensor with a valuable application.Although there are a lot of advantages using capillary force assembled colloidal spheres on the fiber, the process has still needed a lot of minutes. One promising way is to introduce an external field-stimuli photonic structure onto the fiber. In the fourth chapter, structurally colored fiber was fabricated by an electrophoretic deposition method on carbon fiber. The fiber structures look like cylindrical. By applying a voltage and changing electrophoresis time, these fibers exhibit structural colors with reflectance spectra stretch-tunable in the range of visible light. The assembly time of colloidal crystal is improved from a few minutes to tens of seconds. We further developed a horizontal and continuous process to fabricate long range structurally colored fiber. Given the advantages of the device, it may be as a reference of fiber dyeing in the industry.Colloidal spheres with charges can be assembled in the electric field.The magnetic colloid spheres may be also getting colored fiber under the magnetic field.In the fifth chapter, we firstly have prepared Fe3O4@C magnetic particles using solvothermal method. The magnetic particles can be ordered in the direction of magnetic force lines under an external magnetic field. A bragg reflector has been fabricated by assemble the magnetic chains in the acetone. By emulsifying magnetic particles, and combining a micro-fluidic system with magnetic self-assembly and photopolymerization, we have synthesized a magnetochromatic fiber film with fixed structure colors. The structurally colored fiber shows good mechanical properties due to a chemical bonding between fiber and polymer, and the fracture stress is128.9cN and overmatchs the original fiber.ZnO and Ni doped ZnO colloidal spheres were prepared by solvothermal method. We studied the morphology changes of ZnO spheres by controlling the Ni2+doping concentrations. The results show that the size of Zn1-xNixO decreased with increasing Ni doping concentration, eventually forming nanoparticles assembled by nano-sheet. ZnS and ZnS@SiO2colloidal spheres were prepared by the coprecipitation method in a low temperature. ZnS spheres are uniform with an average diameter of450nm.A new idea of structurally colored fiber controllable with electric field is presented.We think the periodic structures can be changed through the electrophoretic force, and then color performance of colloidal crystals can be adjusted by changing the electric field. The imagination may serve as a way for a display micro-device based on structurally colored fiber.