Study on the preparation and application of structural colored silk fabrics based on photonic crystals
The photonic crystal structure can produce vivid and bright colors by interacting with light in interference,diffraction and scattering with its own physical structure.Compared with traditional chemical dyeing,structural colors have enormous potential application value in the field of textile coloring because of their bright luster and environmental friendliness.Numerous studies show that self-assembly of colloidal microspheres on the surface of textiles to construct photonic crystal structures to generate structural colors is an effective method for preparing structural color textiles,especially represented by impregnation methods such as gravity deposition and vertical deposition.However,the impregnation method has disadvantages of low efficiency and high energy consumption,which limits its promotion and application.Therefore,it is urgent to develop preparation technology with high preparation efficiency and low equipment requirements.In addition to the preparation technology,the performance of textile substrates is also an important factor affecting the development of structural colors based on photonic crystals.Numerous studies have found that the background color of the substrate has a significant impact on the brightness of the structural colors of photonic crystals.It is unanimously found that a black background is most conducive to constructing photonic crystals with bright structural colors,while photonic crystals constructed on a white background have the darkest structural colors.At present,the most common practice is to first dye the textile substrate with black materials,and then the treated textile is used as the substrate to construct photonic crystals.Pre-coloring not only increases the preparation process,but also consumes energy and time.It is a hot research topic to obtain bright structural colors based photonic crystals quickly and efficiently on white textile substrates.Vacuum-assisted filtration is a method that utilizes the negative pressure generated during vacuum pumping to achieve solid-liquid separation.It has the advantages of simple operation,high preparation efficiency,and simple equipment.Based on this,if the colloidal microsphere dispersion is treated as filtrate,the process of colloidal microsphere stacking to form photonic crystals happens to be the process of microsphere loading on the textile substrate.This provides a possibility for constructing photonic crystal color structures on textile substrate via vacuum-assisted filtration method.To construct structural colors based on photonic crystals on white silk fabrics,the article used poly(methyl methacrylate)(P(St-MAA)colloidal microspheres as the basic building blocks of the photonic crystal structure,and a structural color generation assembly solution was prepared by adapting acidic black dyes,then the vacuum-assisted filtration and hand drawing methods were respectively proposed to achieve the color generation of photonic crystal structures on white silk fabrics.First,the influence of the dosage of microsphere assembly solution on the structural coloration in the vacuum-assisted filtration process was investigated.The motion mechanism of microsphere forming photonic crystals on silk fabrics under vacuum-assisted filtration conditions was explored.Afterwards,the rainbow effect of photonic crystal structure on colored silk fabrics was discussed.Finally,in order to achieve patterned color generation of photonic crystal structures on silk fabrics,the application effect of the hand drawing method in color generation of photonic crystal structures on silk fabrics was studied.The characteristics of black color absorbing transmitted and scattered light outside the photonic bandgap can enhance the color saturation of photonic crystal structural colors.This paper used acidic black dyes as absorbing materials,and mixed them with P(St-MAA)colloidal microspheres to form a structural color assembly solution.The photonic crystal color structure was constructed on white silk fabrics by using vacuum-assisted filtration and hand drawing methods to achieve the coloring of silk fabrics.The results show that in the vacuum-assisted filtration process,when the dosage of assembly solution is 2.4 L/m2,223 nm P(St-MAA)colloidal microspheres can simultaneously construct photonic crystals with brighter structural colors on both sides of the silk fabric.At this time,the peak reflectivity of the front and back sides of the structural colored silk fabric is about 18%,suggesting double-sided coloring of the silk fabric is achieved.By comparing the arrangement of 295 nm P(St-MAA)colloidal microspheres on the silk fabric at different times,it is found that the microspheres preferentially construct photonic crystal structures on the opposite side of the silk fabric,meaning that the assembly process of P(St-MAA)colloidal microspheres is"reverse first and then forward".The photonic crystal structure constructed on the silk fabric via vacuum-assisted filtration can obtain structural colors with low iridescent effect,which is similar to the coloring effect of conventional dyes or pigments,and is expected to partially replace traditional dyes or pigments in coloring.By hand drawing,P(St-MAA)colloidal microsphere assembly solutions with particle sizes of 197 nm,223 nm,245 nm,and 295 nm are used as structural colorants to prepare patterned photonic crystal structural colors of monochrome,bicolor,and multi-color on the silk fabric,achieving personalized processing of structural colors.The vacuum-assisted filtration method and hand drawing method provide new ways for the rapid preparation of structural colored textiles based on photonic crystals.The results of this study will contribute to providing a practical basis for the application of photonic crystal structure coloring in textile coloring.