阅读说明：本技术 一种无虹彩结构色材料及其制备方法 (Iridescent-free structural color material and preparation method thereof ) 是由 马威 寇东辉 张淑芬 于 2021-07-14 设计创作，主要内容包括：本发明涉及一种无虹彩结构色材料及其制备方法,属于新材料制备领域,具体属于生色新材料制备领域。一种无虹彩的结构色材料,是粘附于聚合物弹性体表面碗状结构上的由两种不同折射率材料交替堆叠形成的周期性多层薄膜结构色材料。本发明可以很好地解决周期性多层光子薄膜结构色角度依存性问题,通过控制层厚可以制备得到不同颜色的无虹彩结构色材料。此方法适用的有机、无机材料广泛,在裸眼检测、智能显示等领域具有良好的应用前景。(The invention relates to a non-iridescent structural color material and a preparation method thereof, belonging to the field of new material preparation, in particular to the field of preparation of new color-generating materials. A non-iridescent structural color material is a periodic multilayer thin-film structural color material formed by alternately stacking two materials with different refractive indexes, which is adhered to a bowl-shaped structure on the surface of a polymer elastomer. The invention can well solve the problem of the angle dependence of the structural color of the periodic multilayer photonic thin film, and can prepare iridescent-free structural color materials with different colors by controlling the layer thickness. The method is suitable for wide range of organic and inorganic materials, and has good application prospect in the fields of naked eye detection, intelligent display and the like.)

1. A non-iridescent structural color material is characterized in that: the material consists of a bowl array and a periodic multilayer photonic thin film solidified on the bowl array;

the bowl array is prepared by polymer elastomer with the aid of a template;

the periodic multilayer photonic film is formed by alternately assembling two materials with different refractive indexes on a substrate;

the material is prepared by peeling a multilayer film assembled on a substrate and transferring to the surface of a bowl array.

2. The material of claim 1, wherein: the polymer elastomer is one of Polydimethylsiloxane (PDMS), polyurethane elastomer (TPU), polyolefin elastomer (TPO) or polyamide elastomer (TPEA).

3. The material of claim 1, wherein: the materials with different refractive indexes comprise inorganic materials and organic materials, wherein the inorganic materials are titanium dioxide, zirconium dioxide, zinc oxide, silicon dioxide or aluminum oxide; the organic material is a homopolymer formed by methyl methacrylate, butyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, styrene, acrylamide and N, N-methylene-bisacrylamide monomers or a copolymer formed among the monomers.

4. The material of claim 1, wherein: the substrate is one of a silicon wafer, a glass sheet or a quartz sheet.

5. The material of claim 1, wherein: the template consists of steel balls or glass beads which are orderly arranged and fixed on a plane glass plate, and the diameter of the steel balls or the glass beads is 0.1-10 mm.

6. The method for preparing the iridescent-free structural color material according to the claim 1 to 5 is characterized by comprising the following process steps:

preparing dispersion or solution of organic polymer and inorganic material;

coating a uniform sacrificial layer on the substrate, and controlling the thickness of the sacrificial layer to be 20-200 nm, wherein the sacrificial layer is a silicon oxide layer which can be etched and decomposed by hydrofluoric acid or a polymer layer which can be calcined and decomposed at high temperature;

selecting two materials with different refractive indexes in the step I, alternately assembling the materials on a sacrificial layer of a base material by adopting a spin coating, spraying or dipping method, adjusting assembly parameters to control the film thickness, drying each assembled layer for 1-120min at the temperature of 30-300 ℃, controlling the thickness of each material layer to be 20-200 nm, and controlling the stacking period to be 1-50;

fourthly, removing the sacrificial layer between the substrate and the periodic film by adopting a hydrofluoric acid etching or high-temperature calcining method to obtain a multilayer film attached to the substrate;

spreading the polymer elastomer pre-polymerization solution on a glass plate for semi-curing, compacting the semi-cured polymer elastomer on a template and completely curing, and stripping the elastomer from the template to obtain a bowl-shaped array structure;

sixthly, placing the polymer elastomer with the bowl array structure obtained in the fifth step on the surface of the periodic film with the sacrificial layer removed in the fourth step, pressing the polymer elastomer to deform the bowl array structure and completely attach the bowl array structure to the surface of the multilayer film, and peeling off the photonic film on the base material and transferring the photonic film to the bowl structure by the polymer elastomer to obtain the iridescent-structure-free color material.

7. The method as claimed in claim 6, wherein in the step (II), the sacrificial layer is prepared by spin coating, dipping or spraying a silicon oxide or polymer dispersion liquid, and the mass percentage concentration of the silicon oxide and polymer dispersion liquid is 2-30%.

8. The method according to claim 6, wherein in the step (iv), the hydrofluoric acid etching method is to soak in a hydrofluoric acid solution with a concentration of 0.5-5% for 0.5-10 min; the high-temperature calcination method is to calcine for 0.5-3 h at the temperature of 400-800 ℃.

9. The method of claim 6, wherein the color of the iridescent-free structural color is adjusted by adjusting the thickness and stacking period of the two different refractive index assembly materials.

10. The method of claim 6, wherein the diameter of the bowl array is adjusted by adjusting the diameter of the steel or glass beads on the die plate.

Technical Field

The invention belongs to the field of new material preparation, particularly belongs to the field of new color-generating material preparation, and particularly relates to a non-iridescent structural color material and a preparation method thereof.

Background

The one-dimensional photon multilayer film is a periodic micro-nano structure formed by alternately stacking two materials with different refractive indexes along one direction, has a photon band gap characteristic, can effectively regulate and control the propagation of light waves, can show visible colors when the photon band gap falls within a visible light range, is called structural colors, and has extremely high application value in the fields of optical switches, filters, solar cells, colorimetric sensing and the like. The one-dimensional periodic multilayer film has the optical properties of wide material source and easy adjustment, and has good application prospect in visual sensing and detection of environmental parameters and the like. However, the highly ordered micro-nano structure gives the color to the photonic film, and simultaneously causes the strong iridescence effect of the color of the photonic structure, namely the color of the photonic film changes along with the change of the observation angle, thereby greatly limiting the application of the color of the photonic structure in the practical colorimetric detection and color display. The existing method for preparing the iridescent-free photon film comprises the steps of depositing or sputtering a layer on the surface of microspheres or fibers and adding an inorganic film structure, or obtaining the iridescent-free photon film through self-assembly of a polymer with a specific structure. The method has limitation on the selection of multilayer film assembly materials, and has important significance and practical value in developing the method with wide applicability.

Disclosure of Invention

In order to solve the problems, the invention adopts a template method to design and prepare a polymer elastomer with a bowl structure as an assembly base material of the iridescent-free photon multilayer film structure color material, and peels off and transfers a periodic structure color film assembled on a plane to a curved surface of a bowl array structure, thereby constructing the iridescent-free structure color material with wide applicability.

The non-iridescent structural color material consists of a bowl array and a periodic multilayer photon film solidified on the bowl array, wherein the bowl array is prepared by polymer elastomer with the aid of a template, the periodic multilayer photon film is formed by alternately assembling two materials with different refractive indexes on a substrate, and the materials are prepared by peeling off the multilayer film assembled on the substrate and transferring the multilayer film onto the surface of the bowl array.

The polymer elastomer is one of Polydimethylsiloxane (PDMS), polyurethane elastomer (TPU), polyolefin elastomer (TPO) or polyamide elastomer (TPEA).

The materials with different refractive indexes comprise inorganic materials and organic materials, wherein the inorganic materials are titanium dioxide, zirconium dioxide, zinc oxide, silicon dioxide or aluminum oxide.

The organic material is a homopolymer formed by methyl methacrylate, butyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, styrene, acrylamide and N, N-methylene bisacrylamide monomers or a copolymer formed among the monomers.

The substrate is one of a silicon wafer, a glass sheet or a quartz sheet.

Further, the template consists of steel balls or glass beads which are orderly arranged and fixed on the plane glass plate, and the diameter of the steel balls or the glass beads is 0.1-10mm, preferably 1-5 mm.

The preparation method of the iridescent-free structural color material comprises the following process steps:

preparing dispersion or solution of organic polymer and inorganic material;

coating a uniform sacrificial layer on the substrate, and controlling the thickness of the sacrificial layer to be 20-200 nm, wherein the sacrificial layer is a silicon oxide layer which can be etched and decomposed by hydrofluoric acid or a polymer layer which can be calcined and decomposed at high temperature;

selecting two materials with different refractive indexes in the step I, alternately assembling the materials on a sacrificial layer of a base material by adopting a spin coating, spraying or dipping method, adjusting assembly parameters to control the film thickness, drying each assembled layer for 1-120min at the temperature of 30-300 ℃, controlling the thickness of each material layer to be 20-200 nm, and controlling the stacking period to be 1-50;

fourthly, removing the sacrificial layer between the substrate and the periodic film by adopting a hydrofluoric acid etching or high-temperature calcining method to obtain a multilayer film attached to the substrate;

spreading the polymer elastomer pre-polymerization solution on a glass plate for semi-curing, compacting the semi-cured polymer elastomer on a template and completely curing, and stripping the elastomer from the template to obtain a bowl-shaped array structure;

sixthly, placing the polymer elastomer with the bowl array structure obtained in the fifth step on the surface of the periodic film without the sacrificial layer in the fourth step, pressing the polymer elastomer to deform the bowl array structure and completely attach the bowl array structure to the surface of the multilayer film, and peeling off the photonic film on the base material and transferring the photonic film to the bowl structure by the polymer elastomer to obtain the iridescent-structure-free color material.

Further, in the step (i), the concentration of the organic polymer, the inorganic material dispersion liquid or the solution is 0.5 to 35% by mass, preferably 1 to 10% by mass.

Further, in the second step, the sacrificial layer is prepared by using a spin coating, dipping or spraying method for silicon oxide or polymer dispersion liquid, and the mass percentage concentration of the silicon oxide and polymer dispersion liquid is 2-30%.

Further, in the step (iv), the hydrofluoric acid etching method is to soak in a hydrofluoric acid solution with a concentration of 0.5-5% for 0.5-10 min.

Further, in the step IV, the high-temperature calcination method is to calcine for 0.5-3 hours at the temperature of 400-800 ℃.

The invention adjusts the color of the non-iridescent structural color by adjusting the thickness and the stacking period of the two different refractive index assembly materials.

The invention adjusts the diameter of the bowl array by adjusting the diameter of steel balls or glass beads on the template.

The invention has the beneficial effects that: the periodic multilayer photon film structure color material has the advantages of beautiful color, no iridescence effect, simple and convenient preparation method and wide application range. The invention can well solve the problem of angle dependence of the structural color of the periodic multilayer film and better shield the influence of the observation angle on the structural color of the multilayer film. The preparation method is simple and convenient, is low in cost, is suitable for wide range of organic and inorganic materials, and has good application prospect in the fields of naked eye detection, intelligent display and the like.

Drawings

FIG. 1 is a graph of the reflectance spectra of the violet iridescent multilayer photonic film obtained in example 13 at different detection angles, wherein the maximum reflectance peak of the periodic multilayer film remains substantially constant as the detection angle increases.

Detailed Description

The following non-limiting examples are presented to enable those of ordinary skill in the art to more fully understand the present invention and are not intended to limit the invention in any way.

The test methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.

Example 1

Taking steel balls with the diameter of 1mm, regularly and tightly arranging the steel balls on a glass plate, and fixing the steel balls on the glass plate by using ultraviolet curing glue to serve as a template. Uniformly mixing a Polydimethylsiloxane (PDMS) monomer and a curing agent in a mass ratio of 25:1, removing bubbles for 30min under a vacuum condition, spreading a prepolymer on a glass plate, placing the glass plate in an oven at 80 ℃ for precuring for 10min, closely attaching the precured PDMS to a steel ball template, heating the glass plate for 30min at 100 ℃ for complete curing, taking the PDMS off the template, and stripping the PDMS from the glass plate to obtain the PDMS elastomer with a bowl array structure.

40.0g of water, 1.0g of cetyltrimethylammonium bromide (CTAB) and 2.5g of a mixed monomer (mass ratio 10:1) of Methyl Methacrylate (MMA) and Acrylamide (AM) were weighed into a reaction flask and stirred for 30min under the protection of nitrogen. After heating in a water bath to 75 ℃, 45.0mg of potassium persulfate (KPS) is added into the reaction flask for reaction for 1 hour. 12.5g of the mixed liquid of MMA and AM monomers was dropped into a reaction flask at a constant rate, and then the temperature was maintained to react for 0.5 hour, thereby obtaining poly (methyl methacrylate-acrylamide) (P (MMA-AM)).

Weighing 4.0g of nano titanium oxide (TiO)₂) Dispersing the powder in 48g of deionized water, adding 48g of ethanol, and performing ultrasonic dispersion to obtain TiO₂And (3) nano sol.

Taking 10 wt% of silicon oxide (SiO)₂) And coating the aqueous dispersion on a silicon wafer by adopting a spin coating method, and heating for 5min at the temperature of 100 ℃ to obtain the silicon oxide sacrificial layer.

Taking 2.0 wt% of P (MMA-AM) aqueous dispersion and 2.0 wt% of TiO₂Nano sol of the above SiO₂And (3) alternately assembling the sacrificial layers by adopting a spin coating method, heating each layer for 10min at 180 ℃ after assembling, and circulating for three periods. Soaking the obtained composite film in 2% hydrofluoric acid solution for 1min, and taking out the film to naturally volatilize and dry the liquid.

And attaching the prepared PDMS bowl array on the surface of the multilayer photonic film, pressing the PDMS elastomer by hands, and taking down the PDMS with the bowl array to obtain the iridescent-free structural color material.

Examples 2 to 4

The procedure is the same as in example 1, but the preparation of the template by using steel balls with diameters of 1.5mm, 2.0mm and 3.0mm, respectively, and the preparation of the PDMS elastomer with a bowl structure.

Examples 5 to 6

The process is the same as example 1, but the sacrificial layer and the periodic multi-layer photonic thin film are assembled by using a glass plate and a quartz plate as a substrate instead of a silicon wafer.

Example 7

Taking steel balls with the diameter of 1mm, regularly and tightly arranging the steel balls on a glass plate, and fixing the steel balls on the glass plate by using ultraviolet curing glue to be used as a template. Uniformly mixing a PDMS monomer and a curing agent in a mass ratio of 25:1, removing bubbles for 30min under a vacuum condition, spreading a prepolymer on a glass plate, pre-curing for 10min in an oven at 80 ℃, closely attaching the pre-cured PDMS to a steel ball template, heating for 30min at 100 ℃ to completely cure the PDMS, taking the PDMS off the template, and peeling off the glass plate to obtain the PDMS elastomer with a bowl-shaped structure.

88g of toluene was charged into a three-necked flask, and 5.0g of sodium bis (2-ethylhexyl) succinate sulfonate (AOT) was dissolved, and heated to 70 ℃ to which 25mg of Azobisisobutyronitrile (AIBN) was added. 5.0g of Acrylic Acid (AA) and 0.2g of N, N-Methylene Bisacrylamide (MBA) are dissolved in 5.0g of deionized water, the monomer solution is dropwise added into the reaction solution, and the reaction is continuously stirred for 1 hour after the dropwise addition is finished, so that the target poly (acrylic acid-N, N-methylene bisacrylamide) (P (AA-MBA)) microemulsion is obtained. Adding ethanol into the product, demulsifying, filtering to obtain white solid, and dispersing in water system to obtain P (AA-MBA) nanogel water dispersion.

4.0g of nano titanium oxide powder is weighed and dispersed in 48g of deionized water, 48g of ethanol is added, and ultrasonic dispersion is carried out to obtain the titanium oxide nano sol.

And (3) coating the nano silicon oxide aqueous dispersion liquid with the concentration of 10 wt% on a silicon wafer by adopting a spin coating method, and heating for 5min at the temperature of 100 ℃ to obtain the silicon oxide sacrificial layer.

Taking 2.0 wt% of P (AA-MBA) water dispersion and 2.0 wt% of TiO₂Nano sol of the above SiO₂And (3) alternately assembling the sacrificial layers by adopting a spin coating method, heating at 180 ℃ for 10min after each layer is assembled, and circulating for three periods. Soaking the obtained composite film in 2% hydrofluoric acid solution for 1min, and taking out the film to naturally volatilize and dry the liquid.

And attaching the prepared PDMS bowl array on the surface of the multilayer photonic film, pressing the PDMS elastomer by hands, and taking down the PDMS with the bowl array to obtain the iridescent-free structural color material.

Examples 8 to 10

The procedure is the same as in example 7, but the preparation of the template using steel balls having diameters of 1.5mm, 2.0mm and 3.0mm, respectively, and the preparation of the PDMS elastomer having a bowl structure.

Examples 11 to 12

The procedure is as in example 7, except that the sacrificial layer and the periodic multi-layer photonic thin film are assembled using a glass wafer and a quartz wafer, respectively, instead of the silicon wafer as a substrate.

Example 13

Taking steel balls with the diameter of 1mm, regularly and tightly arranging the steel balls on a glass plate, and fixing the steel balls on the glass plate by using ultraviolet curing glue to be used as a template. Uniformly mixing a PDMS monomer and a curing agent in a mass ratio of 25:1, removing bubbles for 30min under a vacuum condition, spreading a prepolymer on a glass plate, pre-curing for 10min in an oven at 80 ℃, closely attaching the pre-cured PDMS to a steel ball template, heating for 30min at 100 ℃ to completely cure the PDMS, taking the PDMS off the template, and peeling off the glass plate to obtain the PDMS elastomer with a bowl-shaped structure.

88g of toluene was charged into a three-necked flask, and 5.0g of AOT was dissolved, and heated to 70 ℃ to which 25mg of AIBN was added. 5.0g of Acrylamide (AM) and 0.2g of MBA are dissolved in 5.0g of deionized water, the monomer solution is dropwise added into the reaction solution, and the reaction is continued to be stirred for 1 hour after the dropwise addition is finished, so that the target poly (acrylamide-N, N-methylene bisacrylamide) (P (AM-MBA)) microemulsion is obtained. Adding ethanol into the product, demulsifying, performing suction filtration to obtain a white solid, and re-dispersing in a water system to obtain the P (AM-MBA) nanogel water dispersion.

4.0g of nano titanium oxide powder is weighed and dispersed in 48g of deionized water, 48g of ethanol is added, and ultrasonic dispersion is carried out to obtain the titanium oxide nano sol.

And (3) coating the nano silicon oxide aqueous dispersion liquid with the concentration of 10 wt% on a silicon wafer by adopting a spin coating method, and heating for 5min at the temperature of 100 ℃ to obtain the silicon oxide sacrificial layer.

Taking 2.0 wt% of P (AM-MBA) water dispersion and 2.0 wt% of TiO₂Nano sol of the above SiO₂And (3) alternately assembling the sacrificial layers by adopting a spin coating method, heating each layer for 10min at 180 ℃ after assembling, and circulating for three periods. Soaking the obtained composite film in 2% hydrofluoric acid solution for 1min, and taking out the film to naturally volatilize and dry the liquid.

And attaching the prepared PDMS bowl array on the surface of the multilayer photonic film, pressing the PDMS elastomer by hands, and taking down the PDMS with the bowl array to obtain the iridescent-free structural color material.

Examples 14 to 16

The procedure is as in example 13, but the PDMS elastomer with a bowl structure is prepared by preparing templates using steel beads with diameters of 1.5mm, 2.0mm and 3.0mm, respectively.

Examples 17 to 18

The process is the same as example 1, but the sacrificial layer and the periodic multi-layer photonic thin film are assembled by using a glass plate and a quartz plate as a substrate instead of a silicon wafer.

Example 19

Taking steel balls with the diameter of 1mm, regularly and tightly arranging the steel balls on a glass plate, and fixing the steel balls on the glass plate by using ultraviolet curing glue to be used as a template. Uniformly mixing a PDMS monomer and a curing agent in a mass ratio of 25:1, removing bubbles for 30min under a vacuum condition, spreading a prepolymer on a glass plate, pre-curing for 10min in an oven at 80 ℃, closely attaching the pre-cured PDMS to a steel ball template, heating for 30min at 100 ℃ to completely cure the PDMS, taking the PDMS off the template, and peeling off the glass plate to obtain the PDMS elastomer with a bowl-shaped structure.

88g of toluene was charged into a three-necked flask, and 5.0g of AOT was dissolved, and heated to 70 ℃ to which 25mg of AIBN was added. 5.0gAA and 0.2g of MBA are dissolved in 5.0g of deionized water, the monomer solution is dropwise added into the reaction solution, and the reaction is continued to be stirred for 1 hour after the dropwise addition is finished, so that the target P (AA-MBA) microemulsion is obtained. Adding ethanol into the product, demulsifying, performing suction filtration to obtain a white solid, and re-dispersing in a water system to obtain a P (AA-MBA) nanogel water dispersion.

40.0g of water, 1.0g of CTAB and 2.5g of mixed monomers of MMA and AA (mass ratio of 10:1) are weighed into a reaction flask and stirred for 30min under the protection of nitrogen. After heating in a water bath to 75 ℃, 45.0mg of KPS was added to the reaction flask for reaction for 1 hour. Dropping 12.5g of the MMA and AA monomer mixed solution into a reaction bottle at a uniform speed, and then keeping the temperature for reaction for 0.5h to obtain the P (MMA-AA) copolymer microemulsion.

Taking 10 wt% of SiO₂And coating the aqueous dispersion on a silicon wafer by adopting a spin coating method, and heating for 5min at the temperature of 100 ℃ to obtain the silicon oxide sacrificial layer.

Taking 2.0 wt% of P (AA-MBA) and 2.0 wt% of P (A-MBA)MMA-AA) aqueous dispersion on SiO₂And (3) alternately assembling the sacrificial layers by adopting a spin coating method, heating at 180 ℃ for 10min after each layer is assembled, and circulating for three periods. Soaking the obtained composite film in 2% hydrofluoric acid solution for 1min, and taking out the film to naturally volatilize and dry the liquid.

And attaching the prepared PDMS bowl array on the surface of the multilayer photonic film, pressing the PDMS elastomer by hands, and taking down the PDMS with the bowl array to obtain the iridescent-free structural color material.

Examples 20 to 22

The procedure is as in example 19, but the PDMS elastomer with a bowl structure is prepared by preparing templates using steel beads with diameters of 1.5mm, 2.0mm and 3.0mm, respectively.

Examples 23 to 24

The same procedure as in example 19 was followed, except that a glass wafer and a quartz wafer were used as the substrate to assemble the sacrificial layer and the periodic multi-layered photonic thin film, respectively.

Example 25

Taking steel balls with the diameter of 1mm, regularly and tightly arranging the steel balls on a glass plate, and fixing the steel balls on the glass plate by using ultraviolet curing glue to be used as a template. Uniformly mixing a PDMS monomer and a curing agent in a mass ratio of 25:1, removing bubbles for 30min under a vacuum condition, spreading a prepolymer on a glass plate, pre-curing for 10min in an oven at 80 ℃, closely attaching the pre-cured PDMS to a steel ball template, heating for 30min at 100 ℃ to completely cure the PDMS, taking the PDMS off the template, and peeling off the glass plate to obtain the PDMS elastomer with a bowl-shaped structure.

40.0g of water, 1.0g of CTAB and 2.5g of mixed monomers of MMA and AA (mass ratio of 10:1) are weighed into a reaction flask and stirred for 30min under the protection of nitrogen. After heating in a water bath to 75 ℃, 45.0mg of KPS was added to the reaction flask for reaction for 1 hour. Dropping 12.5g of the MMA and AA monomer mixed solution into a reaction bottle at a uniform speed, and then keeping the temperature for reaction for 0.5h to obtain the P (MMA-AA) copolymer microemulsion.

4.0g of nano titanium oxide powder is weighed and dispersed in 48g of deionized water, 48g of ethanol is added, and ultrasonic dispersion is carried out to obtain the titanium oxide nano sol.

Taking 5.0 wt% of P (MMA-AA) water dispersion, coating the water dispersion on a silicon wafer by adopting a spin coating method, and heating for 5min at the temperature of 100 ℃ to obtain a P (MMA-AA) sacrificial layer.

Taking SiO with the mass fraction of 2.0 wt%₂Aqueous dispersion and 2.0 wt% TiO₂And (3) assembling the nano sol on the P (MMA-AA) sacrificial layer alternately by adopting a spin coating method, heating and treating each layer for 10min at 180 ℃ after assembling, and circulating for three periods. And placing the obtained composite membrane in a muffle furnace, calcining for 1h at 500 ℃, and removing the polymer sacrificial layer.

And attaching the prepared PDMS bowl array on the surface of the multilayer photonic film, pressing the PDMS elastomer by hands, and taking down the PDMS with the bowl array to obtain the iridescent-free structural color material.

Examples 26 to 28

The procedure is as in example 25, but the PDMS elastomer with a bowl structure is prepared by preparing templates using steel beads with diameters of 1.5mm, 2.0mm and 3.0mm, respectively.

Examples 29 to 30

The same procedure as in example 25 was followed, except that the sacrificial layer and the periodic multi-layered photonic thin film were assembled using a glass plate and a quartz plate, respectively, instead of the silicon wafer as a substrate.

Example 31

Taking steel balls with the diameter of 1mm, regularly and tightly arranging the steel balls on a glass plate, and fixing the steel balls on the glass plate by using ultraviolet curing glue to be used as a template. Uniformly mixing a PDMS monomer and a curing agent in a mass ratio of 25:1, removing bubbles for 30min under a vacuum condition, spreading a prepolymer on a glass plate, pre-curing for 10min in an oven at 80 ℃, closely attaching the pre-cured PDMS to a steel ball template, heating for 30min at 100 ℃ to completely cure the PDMS, taking the PDMS off the template, and peeling off the glass plate to obtain the PDMS elastomer with a bowl-shaped structure.

40.0g of water, 1.0g of CTAB and 2.5g of mixed monomers of MMA and AM (mass ratio 10:1) are weighed into a reaction flask and stirred for 30min under the protection of nitrogen. After heating in a water bath to 75 ℃, 45.0mg of KPS was added to the reaction flask for reaction for 1 hour. Dropping 12.5g of the MMA and AM monomer mixture into a reaction bottle at a uniform speed, and then keeping the temperature for reaction for 0.5h to obtain the P (MMA-AM) copolymer microemulsion.

Taking 5.0 wt% of P (MMA-AM) water dispersion, coating the water dispersion on a silicon wafer by adopting a spin coating method, and heating for 5min at the temperature of 100 ℃ to obtain a P (MMA-AM) sacrificial layer.

Taking SiO with the mass fraction of 2.0 wt%₂And (3) alternately assembling the aqueous dispersion and 2.0 wt% of ZnO nano sol on the P (MMA-AM) sacrificial layer by adopting a spin coating method, heating and treating each layer at 180 ℃ for 10min after assembling, and circulating for three periods. And placing the obtained composite membrane in a muffle furnace, calcining for 1h at 500 ℃, and removing the polymer sacrificial layer.

And attaching the prepared PDMS bowl array on the surface of the multilayer photonic film, pressing the PDMS elastomer by hands, and taking down the PDMS with the bowl array to obtain the iridescent-free structural color material.

Examples 32 to 34

The procedure is as in example 31, but the PDMS elastomer with a bowl structure is prepared by preparing templates using steel beads with diameters of 1.5mm, 2.0mm and 3.0mm, respectively.

Examples 35 to 36

The same procedure as in example 31 was followed, except that the sacrificial layer and the periodic multi-layered photonic thin film were assembled using a glass plate and a quartz plate, respectively, instead of the silicon wafer as a substrate.