Research On Preparation And Modification Of Structure Color Film Based On SiO₂

The photonic crystal structure color is derived from the interaction between its own long-range ordered periodic structure and light.Therefore,compared with traditional pigments,it has a lot of advantages,such as non-toxic,environmental friendly,high saturation,and never fade.However,the photonic crystal structure is anisotropic,and the central wavelength of the photonic forbidden band changes with the crystal orientation.Hence,the structural color will change with the different viewing angles,which is called iridescent.To solve the problem,researchers have broken the long-range order of photonic crystals to obtain short-range ordered and long-range disordered amorphous photonic crystal structures.This structure can diffuse the scattered light in any direction in space.It can suppress iridescence by increasing the diffuse reflection of light and reducing the directivity of the reflected light.However,the short-range ordered region obtained by this traditional amorphization method is very small,and the order degree of structure is too low to inevitably reduces the saturation and brightness of the structural color.Besides,it is difficult to carry out industrialized mass production as the preparation process is complicated.Therefore,it is significant for the practical application of photonic crystal structural color materials in color display and related fields that the saturation and brightness of the structural color can be ensured while eliminating the iridescence.This paper finds that a polycrystalline structure composed of nanospheres can effectively eliminate iridescence and improve the brightness and saturation of the structure color.Based on this,non-iridescent structure color films with superhydrophobic properties are prepared on a variety of white substrate surfaces and wetting and self-cleaning properties of them are investigated.The main work of this paper is as follows:(1)Using St(?)ber method,five kinds of silica nanospheres with different particle sizes were prepared by changing the amount of ethanol.The surface morphology,dispersibility,particle size uniformity and phase structure were investigated by field emission scanning,particle size statistics and XRD analysis.(2)Introduce the concept of polycrystals into structural colors,and propose that the polycrystalline structure composed of nanospheres can eliminate iridescence and improve the brightness and saturation of structural colors,which have been successfully verified through experiments:taking silica nanospheres as self-assembly block,structural color film with polycrystalline structure was prepared by adjusting the self-assembly time of the nanospheres.The surface morphology,micro-structure and optical properties of films were investigated by field emission scanning,optical pictures,surface roughness and reflection spectra.It is proved that the structured color film is non-iridescent with high quality saturation and brightness.(3)Based on(2),a certain amount of graphene nanosheets were doped into the silica nanospheres suspension to prepare high-quality non-iridescent structured films on a variety of white substrates(PVC,aluminum sheet,paper,glass).The graphene nanosheets were characterized by SEM,XRD,reflection spectrum and optical pictures,and the optimal doping amount of graphene was determined.(4)The surface of stucture color films was modified by 1H,1H,2H,2H-perfluorooctyltriethoxysilane with low surface energy and non-iridescent structure color films with super hydrophobic properties were prepared on various substrates.Surface chemical analysis of the films before and after hydrophobic treatment were performed by XPS and infrared spectroscopy;the wettability of the film surface was characterized by a contact angle meter,the contact angle reached 150oand the roll angle is 3o.Besides,the film also showed good self-cleaning performance.