Research On The Mechanism Of Structural Colors With Micro-nano Structures And Its Applications On Fibers

Structural color, also called physical color, is produced by light interference, diffraction andscattering in the special micro-nano structures. Structural color can be presented in the fiber byimitating the structures of natural organisms, which is expected to overcome the problems of thewater waste and pollution in the textile printing and dyeing. The research of the relations betweenthe structural color and micro-nano structures, and the feature of color development in differentstructures, actually contributes to the development of bionic structure color products and theadvancement of micro-nano optical technology.To begin with the mechanism of color development of micro-nano structures, this thesisexplores thin film interference and its color feature, the microscopic structures of butterfly scalesand the chromogenic mechanism, the optical properties of artificial structure color products, also,designs and optimizes the bionic structural color in the polymer fiber. The main research contentsand conclusions are as follows:(1) This thesis has simulated the reflection features of single layer film and multilayer thinfilm by FDTD Solutions, and analyzed the influence of structure parameters on the color. In singlelayer film, the greater the film refractive index is, the greater its reflectivity is. Incident anglechanges will affect the location of the spectrum, which will change corresponding color. In themultilayer film, when the difference between refractive indexes of two thin films is large, with theincreasing of the number of layers, the biggest reflectivity increases rapidly. While the differenceis small, then it increases slowly. But when the number of the layers is large enough, themaximum reflectivity is very big, even up to100%. In addition, the reflectivity of multilayermembrane is closely related to the light incident angle. When the sum of the optical thicknesses of two thin layers remains unchanged, their ratio change has no effect on the structural color. Theresearch provides reference for the design of artificial structure color membranous material.(2) Through scanning electron microscopy (SEM), very fine structure could be observed onthe surfaces of the blue area scales of Sasakia charonda and yellow area scales of Papilio xuthus.By transmission electron microscope (TEM) observation on their cross section structure, thecorresponding structural parameters was obtained, then the structure model was established, andoptical simulation was done and analyzed. Through analysis and calculation, the structural color,corresponding to the structure model of the blue area scales of Sasakia charonda, was literallybright blue, which was in accordance with the sample color. While the structural color in themodel of Papilio xuthus presented high-saturation yellow, which was also matched the samplecolor. Both structural models provided a good reference for the design of artificial structural colorproducts.(3) Structural coloration mechanism was analyzed in the artificial structural color products.Observed by scanning electron microscopy, Angelina fiber was a kind of structural color fiberwith layered structure in the cross section, and the thickness of each layer of polymer wascarefully designed, just like Morphotex fiber, both were due to thin film interference to coloration.This thesis also analyzed the optical characteristics of the blazed grating. CD disk was a kind ofrough blazed grating, and it focused the diffraction light on the groove surface direction andstrengthened intervention, shinning substantially. Different diffraction angles produced differentprincipal maximum stripes, when it came to composite white light with different wavelengths,diffraction of lights were dispersed and formed a rainbow.(4) Based on the structural coloration theory and samples analysis, this thesis designedstructural color fiber with special microscope structure by biomimetic method. Inspired by thestructure of sea mice bristles, this thesis designed a kind of fiber with honeycomb structure, whichwas well combined with square lattice and triangular lattice structures, adopting densely arranged,green color, as a good structural color, was finally obtained. The color was stable and not affectedby the light incident angle.