组装条件对涂布法制备SiO2结构色涂层光谱性质影响研究

为了实现结构色涂层在纸张表面的快速制备，研究不同组装条件对SiO₂结构色涂层呈色效果的影响，采用快速涂布的方法，在纸张表面制备出了大面积且具有随角异色特性的结构色涂层。探讨SiO₂微球粒径、分散液浓度及涂布次数等因素对结构色涂层光学特性的影响，通过优化自组装条件和分析周期性结构构筑类型，阐明快速涂布法构建的SiO₂微球在激光打标纸上的自组装过程及结构色呈色机理。应用数码相机、3D激光共聚焦形貌测量显微镜等仪器对样品的颜色外观和微观结构进行测量，表征样品的呈色性能及表面结构。使用X-Rite MA68Ⅱ多角度分光光度仪及光纤光谱仪测量反射光谱，进而用CIEL*a*b*色度值对制备的结构色涂层的光学性能进行分析。结果表明，通过快速涂布自组装法制备所得的结构色涂层，SiO₂微球粒径尺度对样品色调影响显著，随着微球粒径的增加，反射光谱中心波长发生红移，且该涂层有角度依赖特性，当固定入射角度为45°时，随着探测方向与镜面反射方向夹角的增大，中心波长发生红移；微球溶液的浓度可以调控结构色涂层反射光谱曲线的半高宽及反射率峰值，进而影响样品的亮度和彩度，而对于光子带隙的位置无明显影响。微球浓度为4%时，样品表面呈现出基材本身的黑色，微球浓度为8%时，200，220和250 nm粒径的样品表面分别可以呈现彩度较低的蓝色、绿色、黄色，微球浓度增加到10%时，纸张表面的结构色涂层彩度提高，色调不变；随着涂布次数的增加，反射光谱曲线的半高宽变窄，且反射峰位发生蓝移，涂布次数达到3次时，反射峰位最接近于根据布拉格定律计算出的理论值，但涂布次数的增加也使得结构色涂层表面产生白色的不均匀现象。

Influence of Assembly Conditions on Spectral Properties of SiO2 Structural Color Coatings Prepared by Rapid Coating Method

In order to realize the rapid preparation of structural colors on the paper surface, and study the effect of different assembly conditions on the color rendering effect of SiO₂ structural color coatings, a rapid coating method to prepare a large area of structural color coating on paper substrates was reported, which has the characteristics of changing color with different a angle. In this article, the effects of SiO₂ microsphere particle size, dispersion concentration and coating times on the optical properties of structural color coatings were discussed. By optimizing the self-assembly conditions and analyzing the type of periodic structure construction, the self-assembly process of the SiO₂ microspheres constructed by the rapid coating method on the laser marking paper and the mechanism of the structural color rendering was clarified. The digital cameras and 3D laser confocal topography measuring microscopes were used to measure the color appearance and microstructure of the samples. The X-Rite MA68Ⅱ multi-angle spectrophotometer and optical fiber spectrometer were used to measure the reflection spectrum, and then the optical properties of the prepared structural color coatings were analyzed with CIEL*A*B* chromaticity values. The results showed that the particle size of the SiO₂ microspheres has a significant effect on the color tone of the samples. As the diameter of the microsphere increases, the center wavelength of the reflection spectrum red shifted. The coating films were angle dependent. When the incident angle was 45°, as the angle between the detection direction and the mirror reflection direction increased, the center wavelength red shifted. The concentration of the microsphere solution can adjust the half-height width and peak reflectance of the structural color coating, which in turn affects the brightness and saturation of the sample, but has no obvious effect on the position of the photonic band gap. When the concentration of microspheres was 4%, the surface of the sample showed the black color of the substrate. When the concentration of microspheres was 8%, the different structural colors of blue, green and yellow with lower chroma were adjusted by changing the diameters of SiO₂ from 200, 220 to 250 nm. When the concentration of microspheres was increased to 10%, the chroma of the structural color coating on the paper surface was improved, but the hue was unchanged. As the number of coatings increases, the half-height width of the reflection spectrum curve narrowed, and the reflection peak blue shifted. When the coating frequency reached 3 times, the peak wavelength of the reflectance was closest to the theoretical value calculated according to Bragg’s law. However, the increase in the number of coatings caused white unevenness on the surface of the structural color coating.