Micro-nano fiber film based on structural color and preparation method thereof

Abstract

The application provides a kind of micro-nano fiber membrane based on structural color and its preparation method.Nano microspheres are added to solvent, and dispersed by magnetic stirring and ultrasonic treatment to obtain a dispersion with a mass fraction of 1-5wt%;black material is added to N,N dimethylformamide, and after ultrasonic treatment, acetone and polyvinylidene fluoride are added to obtain a spinning solution;using electrospinning process, a micro-nano fiber membrane is prepared;the nano microsphere dispersion is deposited on the electrospun membrane doped with black material by gravity to obtain a micro-nano fiber membrane based on structural color.The micro-nano fiber membrane provided by the application can present different colors on the gray-black membrane with different particle sizes of micro-nano microspheres, its preparation method is simple, the structural color prepared does not need any dye, the color is uniform and bright, the black material in the micro-nano fiber membrane can effectively reduce multiple incoherent scattering in the structural color material, improve color saturation, and prevent color from photobleaching.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of structural color materials, and different colors are presented by co-assembling nanomicro spheres and micro-nanofiber membranes based on their unique structures. BACKGROUND

[0002] From the perspective of materials, nanostructured color only needs to control the nanostructure morphology and geometry to generate structural color using various materials (metal, dielectric, semiconductor, etc.). In contrast, pigments and dyes require specific chemical composition and molecular electronic structure to produce specific colors. Traditional conventional dyes may undergo molecular degradation due to photobleaching, heating, etc., but if the structure of the nanostructured color remains intact, the color can exist all the time.

[0003] In recent years, relevant personnel have begun to study the coloring technology of micro-nanofiber membranes, enriching the research direction of nanofiber membranes. The research on nanofiber coloring mainly concentrates in foreign countries, and most of the coloring uses synthetic dyes, which often causes serious environmental pollution. Moreover, due to the small size of electrospun micro-nanofibers, there is little research on their dyeing performance, and existing dyeing processes will face new challenges.

[0004] Before the present application was made, Chinese invention patent CN110983456A disclosed a preparation method of a composite structure colored nanofiber membrane. Dyes with different chemical structures were coated inside a polymer nanomicro sphere matrix through the high-speed shearing action of fine emulsion ultrasonic, and after removing the volatile solvent under sealed reduced pressure conditions, the solvent-type dyes were uniformly dispersed in the water phase with the help of the polymer carrier with uniform particle distribution. The prepared dye / polymer composite nanodispersion can directly obtain nanofibers with different colors by means of electrospinning. However, its operation is complex, and the use of high polymers and dyes will pollute the environment. Chinese invention patent CN113461985A provides a preparation method of a high-brightness high-adhesion low-angle-dependent structural color film, in which different proportions of epoxy resin pre-gel are doped in an ethanol solution of monodisperse silica nanomicro spheres, and the solution is dropped on substrates of different materials, and a temperature control platform is used for heating to evaporate and self-assemble to form a structural color film. The technical scheme adopted has the following limitations: the doped epoxy resin and gel will penetrate into the gaps of the silica microspheres, changing the refractive index of the structural color and the color, and the preparation process is complex. SUMMARY

[0005] The present application provides a micro-nanofiber membrane based on structural color and a preparation method thereof, which are simple to operate and have high saturation, high brightness and high adhesion.

[0006] In order to achieve the above-mentioned application purposes, the present application adopts the following technical solutions:

[0007] Provided is a preparation method of a micro-nano fiber membrane based on structural color, comprising the following steps:

[0008] (1) adding nano microspheres into a solvent of ethanol or water, and performing magnetic stirring and ultrasonic dispersion to obtain a dispersion liquid with a mass fraction of 1-5 wt%; the nano microspheres have a particle size of 150-420 nm and a monodisperse index of ≤0.1; the solvent is ethanol or water;

[0009] (2) adding a black material into N,N-dimethylformamide at a mass concentration of 0.1-5%, and performing ultrasonic treatment for 30-60 min; adding acetone at a mass ratio of N,N-dimethylformamide:acetone of 3:2, and then adding polyvinylidene fluoride at a mass concentration of 8-16%; performing magnetic stirring treatment at a water bath temperature of 40-60℃ for 3-6 h, and naturally cooling to room temperature to obtain a spinning liquid; and using an electrostatic spinning process to prepare a micro-nano fiber membrane;

[0010] (3) under room temperature conditions, immersing the micro-nano fiber membrane in ethanol, and then placing the micro-nano fiber membrane in a flat-bottomed container; slowly pouring the dispersion liquid prepared in step (1) at 50-70 mL / cm 2 on the surface of the micro-nano fiber membrane, and standing for 20-48 h to uniformly deposit the nano microspheres on the micro-nano fiber membrane under the action of gravity to obtain a micro-nano fiber membrane based on structural color.

[0011] The nano microspheres are silica nano microspheres prepared by the St ber method.

[0012] The black material is one of carbon nanotubes, carbon black, polydopamine and graphene, or any combination thereof.

[0013] The process conditions of electrostatic spinning are as follows: a voltage of 13-18 KV, an inner diameter of a spinning needle of 0.51±0.02 mm, a silicon oil paper receiver fixed on a roller, a distance between the needle and the receiver of 15-20 cm, a roller rotation speed of 200 rpm / min, and a spinning liquid advancing rate of 1-1.5 mL / h.

[0014] The technical scheme further comprises a micro-nano fiber membrane based on structural color prepared by the above preparation method.

[0015] The nano microspheres provided by the application are nanosilica, which is prepared by the classical Stober method. The specific preparation method is as follows: 3-10 mL of ammonia water, 8-30 mL of deionized water and 50-120 mL of anhydrous ethanol are uniformly mixed for 5-20 min, and tetraethyl orthosilicate (TEOS) is added twice, 1-2 mL of TEOS is added first time, and 3-10 mL of TEOS is added after 15 min. The solution is stirred at a speed of 300-700 rpm, and the temperature is 20-35 DEG C, and the reaction is carried out for 4-10 h. After the reaction is completed, the reaction solution is centrifuged at a centrifugal speed of 5000-8000 rpm for 5 min, the upper clear liquid is poured out, and then the microspheres are dispersed again with deionized water or anhydrous ethanol, and the cleaning is carried out for three times. After drying in an oven, the nanosilica microspheres required for preparing structural color are obtained.

[0016] The application adopts an electrospinning process to prepare micro-nano fiber membranes containing black materials, and different mass ratios of black materials can be added in the spinning solution to adjust the lightness of the gray-black micro-nano fiber membranes prepared. Since the black material has strong light absorption in the visible light range, it can effectively reduce the multiple incoherent scattering of the structural color material deposited on the membrane, prevent photobleaching, and has strong light absorption in the visible light range, thereby reducing the reflectivity of the material at non-resonant wavelengths and increasing the saturation of the structural color.

[0017] The application uses a more green and environmentally friendly way to dye micro-nano fiber membranes compared with traditional dyeing, which is physical coloring rather than chemical coloring. The use of black materials can effectively reduce the multiple incoherent scattering in the structure and improve the color saturation, and has a wide spectrum of strong light absorption in the visible light range. By adjusting the amount of black pigment, the saturation and brightness of the structural color material can be efficiently controlled, making the structural color material highly customizable.

[0018] The application adopts a simple and easy-to-operate method to construct structural color on the micro-nano fiber membrane. The colloidal microspheres are dispersed in the solvent, and the microspheres will slowly deposit on the substrate micro-nano fiber membrane under the action of gravity. The method is simple and easy to operate, and the required equipment is simple. At the same time, the micro-nano fiber membrane contains black materials, which can adjust the color of the structural color material and improve the brightness of the structural color.

[0019] The application combines structural color with micro-nano fiber membranes. Due to the disordered and porous characteristics of the micro-nano fiber membrane, a structural color film with high adhesion and double-sided coloring can be prepared. Although the structural color material has the advantages of bright color, environmental friendliness and never fading, the background light and stray light outside the photonic band gap (PBG) make the structural color dark. Therefore, by doping black pigment material in the micro-nano fiber membrane, the incoherent scattered light can be absorbed, and the structural color is brighter.

[0020] The PVDF doped black material micro-nano fiber membrane obtained by electrostatic spinning is a hydrophobic membrane, and because the fiber has less polar group and water-soluble group on the macromolecular chain, in the initial self-assembly process, the colloidal microspheres are more inclined to fill the gap between the fibers, and the residual nanoscale microspheres in the dispersion liquid can actively participate in the subsequent self-assembly, which is helpful to manufacture ordered photonic crystals and obtain bright structural color.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] (1) The present application is based on combining the non-fading, environmentally friendly structural color with the micro-nano fiber membrane, and doping the black material in the micro-nano fiber membrane, which can effectively reduce the multiple incoherent scattering in the structural color material, and has strong light absorption ability in the visible light region, thereby improving the color saturation.

[0023] (2) The preparation method of the present application is simple, does not have special requirements for equipment, is not limited by the substrate material, and can assemble the structural color on the substrate in the vessel under room temperature conditions, and can present different colors according to the change of the assembled nanoscale microspheres, which is beneficial to the application of the structural color material in the coloring of the micro-nano fiber membrane. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The scanning electron microscope image and the hydrated particle size diagram of the nanoscale silicon dioxide with an average particle size of about 220 nm provided for the embodiment 1 of the present application are shown in the following figure:

[0025] Figure 2 The scanning electron microscope image and the hydrated particle size diagram of the nanoscale silicon dioxide with an average particle size of about 260 nm provided for the embodiment 2 of the present application are shown in the following figure:

[0026] Figure 3 The scanning electron microscope image and the hydrated particle size diagram of the nanoscale silicon dioxide with an average particle size of about 295 nm provided for the embodiment 3 of the present application are shown in the following figure:

[0027] Figure 4 The reflection spectrum diagram of the nanoscale silicon dioxide with different particle sizes provided for the embodiments of the present application deposited on the micro-nano fiber membrane is shown in the following figure. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be further described below in combination with the drawings and embodiments.

[0029] Embodiment 1

[0030] The present embodiment provides a micro-nano fiber membrane based on structural color, and the preparation process thereof includes the following steps:

[0031] (1) The St ber method, 3 mL of ammonia water, 10 mL of deionized water, 70 mL of anhydrous ethanol are uniformly mixed, and then 4 mL of tetraethyl silicate (TEOS) is added; the obtained solution is stirred at a rotation speed of 500 rpm, and the temperature is kept at 35 DEG C for 4 h; after the reaction is completed, centrifugal treatment is carried out at a centrifugal speed of 8000 rpm for 5 min, the product is washed with ethanol or deionized water for 3 times, and then silica microspheres are prepared, and are dried and stored.

[0032] Referring to the accompanying drawings Figure 1 The scanning electron microscope image (a) and the laser nanoparticle size analyzer for measuring the hydrated particle size of the silica nanomicrospheres by a dynamic light scattering method (b) of the prepared nano-silica in this embodiment are shown in the figure; it can be seen from the figure b that the average particle size of the obtained silica microspheres is about 220 nm; and the measured monodisperse index PDI is 0.060.

[0033] (2) Carbon nanotubes are added into N,N-dimethylacetamide (DMF) at a mass concentration of 1.2%, ultrasonic treatment is performed for 30 min, a certain amount of acetone (the mass ratio of DMF to acetone is 3:2) is added, polyvinylidene fluoride (PVDF) is added at a mass concentration of 14%, and magnetic stirring is performed in a water bath at 40 DEG C for 6 h until the PVDF is completely dissolved; after the stirring is completed, the temperature is cooled to room temperature, and a spinning solution is obtained.

[0034] (3) The spinning solution is injected into a 20 mL syringe, a 21-gauge needle (an inner diameter of 0.51±0.02 mm) is connected, and the needle is placed on a spinning machine; silicon oil paper is attached to a drum to receive the spinning solution, the distance between the needle and the receiving drum is adjusted to 16 cm, the rotation speed of the drum is 200 rpm / min, the advancing rate of the pusher is 1.0 mL / h, and the voltage is 16 KV; and an electrospinning process is used to obtain a micro-nano fiber membrane.

[0035] (4) The micro-nano fiber membrane is placed in a 70 mm culture dish, 20 mL of a silica dispersion solution with an ethanol dispersion mass fraction of 1.5 wt% is poured into the culture dish, and the micro-nano fiber membrane is obtained after natural sedimentation for 24 h at room temperature.

[0036] Referring to the accompanying drawings Figure 4 The reflectance spectra of different particle size nano-silica deposited on the micro-nano fiber membrane provided by the embodiments of the present application are shown in the figure, and it can be seen from the figure that Figure 4 It can be seen that the average particle size of the silica microspheres in this embodiment is about 220 nm, and the micro-nano fiber membrane with blue structural color is obtained.

[0037] Embodiment 2

[0038] (1) St The Ber process involves mixing 3 mL of ammonia, 10 mL of deionized water, and 75 mL of anhydrous ethanol until homogeneous, then adding 4 mL of tetraethyl orthosilicate (TEOS). The solution is stirred at 500 rpm and reacted at 28°C for 4 hours. After reaction, the mixture is centrifuged at 7000 rpm for 5 minutes, washed three times with ethanol or deionized water, and then dried and stored. (See appendix.) Figure 2 Figure 1 shows a scanning electron microscope image (a) of the nano-silica prepared in this embodiment and a laser nanoparticle size analyzer measuring the hydrated particle size of the silica nanospheres by dynamic light scattering method (b). As shown in Figure 1, the average particle size of the silica microspheres obtained in this embodiment is about 260 nm and the monodispersity index (PDI) is 0.053.

[0039] (2) Take 1.2% carbon nanotubes by mass, add N,N dimethylformamide (DMF) and sonicate for 30 min. Add PVDF at a mass-volume ratio of 14% relative to the solution. Add a certain amount of acetone (DMF:acetone mass ratio of 3:2) and magnetically stir in a water bath at 40℃ for 6 h until PVDF is completely dissolved. After stirring, cool to room temperature.

[0040] (3) Inject the spinning solution into a 20mL syringe, attach a No. 21 needle (inner diameter 0.51±0.02), place it on the spinning machine, attach silicone paper to the roller to receive it, adjust the distance between the needle and the receiving cylinder to 16cm, the rotation speed of the roller to 200rpm / min, the propulsion rate of the pusher to 1.0mL / h, and the voltage to 16KV.

[0041] (4) Place the spun micro / nanofiber membrane in a 70 mm petri dish, add 20 mL of a 2.0 wt% silica dispersion dispersed in ethanol, and allow it to settle naturally at room temperature for 24 h. See Appendix. Figure 4 In this embodiment, a micro / nanofiber membrane with a structural color of green was obtained.

[0042] Example 3

[0043] (1) Through St The Ber process involves mixing 3 mL of ammonia, 10 mL of deionized water, and 70 mL of anhydrous ethanol until homogeneous, then adding 5 mL of tetraethyl orthosilicate (TEOS). The solution is stirred at 500 rpm and reacted at 28°C for 4 hours. After reaction, the mixture is centrifuged at 6500 rpm for 5 minutes, washed three times with ethanol or deionized water, and then dried and stored. (See appendix.) Figure 3The scanning electron microscope image (a) and the laser nanoparticle size analyzer for measuring the hydrated particle size of the silica nanomicrospheres by dynamic light scattering method (b) of the nanosilica prepared for the present embodiment; as can be seen from the b figure, the average particle size of the silica microspheres obtained in the present embodiment is about 295 nm; the monodisperse index PDI is measured to be 0.096.

[0044] (2) After adding 1.4% carbon nanotubes by mass ratio to N,N dimethylformamide (DMF) and ultrasonic treatment for 30 min, 14% PVDF by mass volume ratio of the solution was added, a certain amount of acetone (mass ratio of DMF:acetone is 3:2) was added, and magnetic stirring was carried out in a water bath at 40°C for 6h until the PVDF was completely dissolved. After stirring, it was cooled to room temperature at room temperature.

[0045] (3) The spinning solution was injected into a 20 mL syringe, a 21 gauge needle (inner diameter 0.51±0.02mm) was connected, and it was placed on the spinning machine, silicon oil paper was pasted on the drum to receive it, the distance between the needle and the receiving drum was adjusted to 16 cm, the rotating speed of the drum was 200 rpm / min, the advancing rate of the pusher was 1.0 mL / h, and the voltage was 16KV.

[0046] (4) The micro-nano fiber membrane obtained by spinning was placed in a 70 mm culture dish, 20 mL of 1.5wt% silica dispersion liquid dispersed with ethanol was poured into it, and it was naturally settled for 24h at room temperature. See the attached Figure 4 The micro-nano fiber membrane with purple red structural color was prepared in the present embodiment.

Claims

1. A method for preparing micro / nanofiber membranes based on structural color, characterized in that... Includes the following steps: (1) Add nanospheres to solvent ethanol or water, and disperse them by magnetic stirring and ultrasonication to obtain a dispersion with a mass fraction of 1-5 wt%; the nanospheres have a particle size of 150-420 nm and a monodispersity index ≤0.1; the solvent is ethanol or water; (2) Add the black material to N,N dimethylformamide at a mass concentration of 0.1-5% and sonicate for 30-60 min; add acetone at a mass ratio of N,N dimethylformamide:acetone of 3:2, and then add polyvinylidene fluoride at a mass concentration of 8-16%; stir magnetically in a water bath at a temperature of 40-60℃ for 3-6 h, and cool naturally to room temperature to obtain the spinning solution; use electrospinning process to prepare micro / nanofiber membranes; (3) At room temperature, the micro / nanofiber membrane, after being moistened with ethanol, is placed in a flat-bottomed dish, and the dispersion prepared in step (1) is added at a ratio of 50-70 mL / cm³. 2 Slowly pour the mixture onto the surface of the micro / nanofiber membrane and allow it to stand for 20–48 hours. Under the influence of gravity, the nanospheres are uniformly deposited on the micro / nanofiber membrane, resulting in a micro / nanofiber membrane based on structural color.

2. The method for preparing a micro / nanofiber membrane based on structural color according to claim 1, characterized in that: The nanospheres are made using St Silica nanospheres prepared by the ber method.

3. The method for preparing a micro / nanofiber membrane based on structural color according to claim 1, characterized in that: The black material is one of carbon nanotubes, carbon black, polydopamine, and graphene, or any combination thereof.

4. The method for preparing a micro / nanofiber membrane based on structural color according to claim 1, characterized in that: The electrospinning process conditions are as follows: voltage 13-18KV, spinneret inner diameter 0.51±0.02mm, silicone paper receiver fixed on roller, distance from needle to receiver 15-20cm, roller rotation speed 200rpm / min, and spinning solution propulsion rate 1-1.5mL / h.

5. A micro / nanofiber membrane based on structural color obtained by the preparation method according to claim 1.

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