The Fabric Coloring Application Of Structural Color Based On Single-crystal Cu₂O Spheres

Traditional dyeing/pigment coloring of fabrics has the problems such as complicated dyeing process,large water consumption,high cost of wastewater treatment,and easy fading after long-term light exposure.In contrast,the structural colors generated by the light and nanostructure interactions have the advantages of eco-friendliness,bright colors,and anti-fading.It is expected to overcome the high pollution and high energy consumption situation of traditional industries,and open a new chapter in fabric coloring.Therefore,coloring the textile fibers using structural colors has been demonstrated by researchers.In recent years,the structural-colored fabrics have mainly been concerned with the low-refractive spheres such as the Si O₂or polymer to produce colors,which were assembled by depositing the multilayered photonic crystal or amorphous structures on the surface of the fabric.However,the colors obtained by the photonic crystal structure are brilliant but angle-dependent,while the color generated by the amorphous structure is weak.Meanwhile,the thickness（～6-10μm）of the color-generating layers of the two structures above were usually too large to meet the color fastness standard.Thus,developing a method to color fibers with brilliant,non-iridescent,high-fastness structural color output remains a challenge.In this work,based on the strong Mie scattering of single-crystal cuprous oxide（Cu₂O）spheres in the visible light range,a coloring strategy for structural-colored polyester fabrics that can produce beautiful,non-iridescent,and high color fastness colors was developed.Firstly,the coloring of polyester fabrics by single-crystal Cu₂O spheres was studied.Single-crystal Cu₂O spheres with particle sizes ranging from 165 nm to 275 nm were prepared as the building blocks,which were deposited on the surface of polyester fabrics pretreated with commercial binder（polyacrylate）by the spraying method.Due to the higher refractive of the Cu₂O spheres（n～2.7）and its strong Mie scattering ability in the visible light range,～0.6μm of the disordered Cu₂O spheres aggregates on the surface of fibers can produce the visible,beautiful,non-iridescent structural colors with large scales,which is much thinner than the two structures mentioned above.Polyester fabrics with purple,cyan,green,yellow-green,yellow,or orange structural colors can be obtained by simply changing the size of the single-crystal Cu₂O spheres.In addition,the double-sided coloring or colorful pattern of polyester fabrics can also be realized by spraying the different sizes of Cu₂O spheres on the two sides or different areas of the polyester fabrics.Besides,the designed thin layer composed of Cu₂O spheres and a small amount of binder on the surface of fibers greatly improved the color fastness.The dry rubbing,wet rubbing,and light fastness of structural-color polyester fabrics can reach grades 5,4,and 6,respectively.Hence,the obtained structural-colored polyester fabrics with Cu₂O spheres and a small amount of binder can be resistant to external forces such as rubbing,photobleaching,washing,rinsing,stretching,and other external mechanical forces.Further,in order to better play the advantages of structural-color fabrics,the strategy of the aggregating color of single-crystal Cu₂O spheres was extended to the dyeing of aramid fabrics whose surface is chemically inert.As expected,the structural-colored aramid fabrics with vivid non-iridescent bright colors and high color fastness were prepared.By changing the size of single-crystal Cu₂O spheres,the aramid fabrics could be dyed in purple,cyan,green,yellow,or orange structural colors,respectively.Moreover,through a simple coloring craft adjustment,the structural colors on the aramid fabrics could be“Janus”or pattern.After 70hours of simulated sunlight test,the structural color of the Cu₂O-dyed aramid fabric sample has no fading phenomenon and has excellent light fastness.Subsequently,the dry rubbing and wet rubbing fastness of the aramid fabrics with structural color can reach grades 5 and 4.It was sufficient for the prepared aramid fabrics to resist the damage of external forces such as friction,bending,rubbing,and other external mechanical forces.Not only could this strategy make up for the shortcomings of conventional dyeing technology for aramid coloring,but also provided new ideas for overcoming the dyeing difficulty of the other fabrics just like aramid.