阅读说明：本技术 电场可控二氧化硅胶体自组装结构变色器件的制备方法 (Preparation method of electric field controllable silicon dioxide colloid self-assembly structure color-changing device ) 是由 刘志福 任瑛琪 房永征 侯京山 于 2021-08-13 设计创作，主要内容包括：本发明公开了电场可控二氧化硅胶体自组装结构变色器件的制备方法：以正硅酸乙酯、乙醇和氨水为起始原料,制备了不同粒径的二氧化硅胶体,通过蒸发乙醇浓缩乳液。将浓缩后乳液与碳酸丙烯酯和ETPTA混合,蒸干乙醇后将混合液滴入3D打印的“三明治”器件中。在两侧电极ITO导电玻璃施加电压,制得颜色可逆、电场响应结构变色器件。本发明无需染料和电化学反应即可制备具有良好的颜色可逆性、原料简单易得、透明度高的器件,在显示、颜色传感领域有重要的发展前景。(The invention discloses a preparation method of a color-changing device with an electric field controllable silicon dioxide colloid self-assembly structure, which comprises the following steps: taking ethyl orthosilicate, ethanol and ammonia water as starting raw materials, preparing silicon dioxide colloids with different particle sizes, and concentrating the emulsion by evaporating ethanol. And mixing the concentrated emulsion with propylene carbonate and ETPTA, evaporating ethanol to dryness, and dripping the mixed solution into a 3D printed sandwich device. And applying voltage to the ITO conductive glass on the two side electrodes to prepare the color-changing device with the reversible color and the electric field response structure. The invention can prepare the device with good color reversibility, simple and easily obtained raw materials and high transparency without dye and electrochemical reaction, and has important development prospect in the fields of display and color sensing.)

1. A preparation method of a color-changing device with an electric field controllable silicon dioxide colloid self-assembly structure is characterized by comprising the following steps:

step 1): TEOS is used as a starting material, ethanol is used as a solvent, ammonia water is used as a reagent for adjusting pH, and silica colloidal crystals with different particle sizes are prepared through reaction; then washing the mixture with water, washing with alcohol, centrifuging and ultrasonically treating the mixture for many times; dispersing the silicon dioxide colloidal crystals in ethanol, and then concentrating in an oven through thermal evaporation to obtain a concentrated solution;

step 2): adding PC and hydrogel into the concentrated solution, heating in an oil bath, and evaporating ethanol to obtain an electric field controllable structure discoloration solution;

step 3): designing a model and printing in a 3D mode, dropping the color-changing liquid with the electric field controllable structure into the model, respectively inserting two copper sheets into the model, connecting the two copper sheets with a positive electrode and a negative electrode, and observing the color response time by adjusting voltage.

2. The method for preparing the electric field controllable color-changing device with the silicon dioxide colloid self-assembly structure according to claim 1, wherein in the step 1), the volume ratio of TEOS, ethanol and ammonia water is 2-7: 72-88: 3.5 to 9; the reaction temperature is 25-60 ℃, and the reaction time is 2-3 h; the particle size of the silicon dioxide colloidal crystal is 200-350 nm; the temperature of the oven is 25-40 ℃, and the concentration of the concentrated solution is 0.1-0.3 g/mL.

3. The method for preparing a color-changing device with an electric field controllable silica colloid self-assembled structure according to claim 1, wherein in the step 2), the hydrogel is ETPTA, PEGPEA or PEGDA; the proportion of the silicon dioxide concentrated solution, the PC and the hydrogel is 0.5-2 mL: 50-60 μ L: 15 mu L of the solution; the temperature of the oil bath is 90 ℃, and the heating time is 0.5-2 h.

4. The method for preparing a color-changing device with an electric field controllable silica colloid self-assembled structure according to claim 3, wherein the hydrogel is ETPTA.

5. The method for preparing a color-changing device with an electric field controllable silica colloid self-assembled structure according to claim 1, wherein in the step 3), the voltage is applied within the range of 0 to 3V, and the time for applying the voltage each time is not more than 30 s; the color response time is 15-30 s.

6. The method for preparing a color-changing device with an electric field controllable silica colloid self-assembled structure according to claim 1, wherein in the step 3), the mold has a size of 1cm x 1mm and a thickness of 0.1 mm.

7. The method for preparing a color-changing device with an electric field controllable silica gel self-assembly structure according to claim 1, wherein the color-changing device with an electric field controllable silica gel self-assembly structure is a sandwich structure.

Technical Field

The invention relates to a novel structural color-changing device, in particular to a preparation method of a mixed electric field controllable structural color-changing solution of ETPTA and colloidal silicon dioxide and a device.

Background

The self-assembled silica colloidal sphere is a photonic crystal, is a periodic micro-scale structural material, can control the absorption and reflection of photons, and presents different structural colors after white light irradiation due to the existence of a conduction band and a forbidden band. Based on this characteristic, photonic crystals are widely used for color displays, inks and paints, lasers, filters, solar cells, sensors, and the like.

The electric field control structure color-changing liquid is a novel intelligent material, and can move and gather together to the positive pole along the electric field direction under low voltage due to the negative charge of silica colloidal particles, so that the particle spacing and the lattice spacing are reduced, the structural color is changed, and the electric field control structure color-changing liquid has the advantages of environmental friendliness, fastness, low cost, easiness in obtaining materials and the like. The electric field controllable structure color-changing liquid has reversible color and stable property under lower voltage and power, does not need oxidation-reduction reaction, and has important development prospect in display. For example, a new type of two-sided electrochromic device developed by the just-assigned group of Zhao Shi, exhibits a distinctly different colored state on one side than the other when different voltages are applied. This is achieved by inserting optically thin (4-8 nm) metal layers with complex refractive indices into a typical electrochromic structure. (Adv mater.2021,2007314: 1-10). The current traffic lights often need to apply 220V voltage to change color, consuming a large amount of energy. If the color-changing liquid is changed into the color-changing liquid with the electric field controllable structure, the color can be changed in a short time only by the voltage below 3V.

The electrochromic material commonly used is mainly an amorphous tungsten oxide film. For example, Yao uses atmospheric solution deposition (APSD) as an alternative to conventional sputter deposition processes to deposit Al ³⁺Chimerization into WO₃In the thin film, the cycle life is improved due to its smaller radius and multi-electron redox reaction (Nano energy.2020,68: 104350). Although the material has low near infrared transmittance, the visible light transmittance also drops sharply, thereby influencing the lighting capability of the coated glass window. In addition, the chemical properties of tungsten oxide films are heavy due to the instability of the amorphous structureAfter the reoxidation reduction reaction is circulated, the reaction is changed violently, and the color change characteristic of the electric field controllable structure gradually disappears, so that the service life of the circulation is not long.

At present, tungsten trioxide is covered on conductive glass usually on a glass substrate by means of magnetron sputtering or evaporation, but the method has high preparation cost and difficulty, and particularly for products with curved surfaces, the defect is more prominent, and the application of electrochromic materials in large-scale production is also limited.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the electric field controllable structure color-changing material in the prior art has the problems of short cycle service life, low light transmittance, high preparation cost and high difficulty.

In order to solve the technical problems, the invention provides a preparation method of a color-changing device with an electric field controllable silicon dioxide colloid self-assembly structure, which comprises the following steps:

Step 1): TEOS is used as a starting material, ethanol is used as a solvent, ammonia water is used as a reagent for adjusting pH, and silica colloidal crystals with different particle sizes are prepared through reaction; then washing the mixture with water, washing with alcohol, centrifuging and ultrasonically treating the mixture for many times; dispersing the silicon dioxide colloidal crystals in ethanol, and then concentrating in an oven through thermal evaporation to obtain a concentrated solution; the silica colloid ball ensures the tightness of the container in the preparation process, and ensures the monodispersity of colloid synthesis through the surface pressure formed by gas generated by the solution in the reaction process.

Step 2): adding PC and hydrogel into the concentrated solution, heating in an oil bath, and evaporating ethanol to obtain an electric field controllable structure discoloration solution;

step 3): designing a model and printing in a 3D mode, dropping the color-changing liquid with the electric field controllable structure into the model, respectively inserting two copper sheets into the model, connecting the two copper sheets with a positive electrode and a negative electrode, and observing the color response time by adjusting voltage.

Preferably, in the step 1), the improvement of the silica colloidal crystal is adoptedThe preparation method comprises the following steps of (1) preparation; the volume ratio of TEOS, ethanol and ammonia water is 2-7: 72-88: 3.5 to 9; the reaction temperature is 25-60 ℃, and the reaction time is 2-3 h; the particle size of the silicon dioxide colloidal crystal is 200-350 nm; the temperature of the oven is 25-40 ℃, and the concentration of the concentrated solution is 0.1-0.3 g/mL.

Preferably, in the step 2), the hydrogel is ETPTA, PEGPEA or PEGDA; the proportion of the silicon dioxide concentrated solution, the PC and the hydrogel is 0.5-2 mL: 50-60 μ L: 15 mu L of the solution; the temperature of the oil bath is 90 ℃, and the heating time is 0.5-2 h.

More preferably, the hydrogel is ETPTA.

Preferably, in the step 3), the voltage application range is 0-3V, and the time for applying the voltage every time does not exceed 30 s; the color response time is 15-30 s.

Preferably, in the step 3), the size of the model is 1cm × 1cm × 1mm, and the thickness is 0.1 mm.

Preferably, the electric field controllable silicon dioxide colloid self-assembly structure color-changing device is of a sandwich structure. The device is designed to be of a sandwich structure, and the problem of uneven liquid film distribution caused by surface tension is solved.

The preparation process is simple and convenient, the required equipment is simple, and the environment is friendly; the synthesized electric field controllable structure color-changing liquid has the characteristics of adjustable color, high light transmittance, repeated utilization for many times, strong conductivity and stable property. The method of the invention expands the application fields of display, color sensing and the like.

Drawings

FIG. 1 is a schematic diagram of the color change of the present invention;

FIG. 2 is a device assembly diagram of the present invention;

FIG. 3 is an SEM image of silica having a particle size of 225 nm;

FIG. 4 is a color change response diagram of the electrochromic liquid at 2.5V;

FIG. 5 is a display comparison of a traffic light and the present invention;

FIG. 6 is a 3D model layout.

Detailed Description

In order to make the invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.

Example 1

This example provides a method for preparing a color-changing liquid with an electric field controllable structure, which is used to prepare a silica colloidal crystal with a particle size of 350 nm.

TEOS, ethanol and ammonia water are mixed according to the material ratio of 2 mL: 88 mL: 9mL of the mixture is mixed, the reaction is carried out for 2 hours at the temperature of 25 ℃, and then the mixture is subjected to water washing, alcohol washing, centrifugation and ultrasound for many times; finally dispersing the colloidal crystal in pure ethanol until the concentration is 0.2 g/mL;

and (3) mixing the silicon dioxide concentrated solution, PC and ETPTA according to the material ratio of 1 mL: 60 μ L of: reacting 15 mu L in an oil bath at 90 ℃ for 1.5h, and evaporating ethanol to obtain the green electric field controllable structure discoloring liquid. The assembly schematic diagram of the sandwich structure device is shown in fig. 2, the upper layer and the lower layer are made of conductive ITO glass, the middle interlayer is a color-changing region, the assembly liquid is dripped into a model, positive and negative electrodes are respectively clamped on two copper sheets, and 0-3V voltage is applied for 30 s.

Fig. 1 is a schematic diagram of the color change of the electric field regulation structure, and it can be seen from the diagram that the distance and the structure of the colloid balls change before and after the electric field is applied. Since the surface of the colloid sphere has charges, the colloid sphere is generally selectively moved to the positive electrode, thereby generating a self-assembly phenomenon locally. The self-assembled colloid ball reflects light waves and changes color, and the size, the distance and the wavelength of the colloid ball have a certain relation according to the Bragg principle, so that the color of the device changes along with the change of an electric field. Meanwhile, the materials used by the invention are all green, non-toxic and harmless, and are ideal color-changing devices. The principle can also be called as the self-assembly of the colloid ball regulated and controlled by the electric field, and provides theoretical reference value for preparing energy-saving and efficient color-changing devices.

Example 2

This example provides a method for preparing a color-changing liquid with an electric field controllable structure, which is to prepare a silica colloidal crystal with a particle size of 225nm, and its SEM is shown in fig. 3.

TEOS, ethanol and ammonia water are mixed according to the material ratio of 2 mL: 88 mL: 9mL of the mixture is mixed, the reaction is carried out for 2 hours at the temperature of 45 ℃, and then the mixture is subjected to water washing, alcohol washing, centrifugation and ultrasound for many times; finally dispersing the colloidal crystal in pure ethanol until the concentration is 0.2 g/mL;

And (3) mixing the silicon dioxide concentrated solution, PC and ETPTA according to the material ratio of 1 mL: 60 μ L of: reacting 15 mu L in an oil bath at 90 ℃ for 2h, and evaporating ethanol to obtain the red electric field controllable structure color-changing liquid.

The assembled droplets are dropped into a model as shown in fig. 2, and combined with a 3D printing model as shown in fig. 6, a voltage of 2.5V is applied for 30s, and the color change is shown in fig. 4. The fast response can occur at low voltages, enabling a red to green transition.

Example 3

This example provides a method for preparing a color-changing liquid with an electric field controllable structure, which is used to prepare a silica colloidal crystal with a particle size of 215 nm.

TEOS, ethanol and ammonia water are mixed according to the material ratio of 2 mL: 88 mL: 9mL of the mixture is mixed, the reaction is carried out for 2 hours at the temperature of 50 ℃, and then the mixture is subjected to water washing, alcohol washing, centrifugation and ultrasound for many times; finally dispersing the colloidal crystal in pure ethanol until the concentration is 0.2 g/mL;

and (3) mixing the silicon dioxide concentrated solution, PC and ETPTA according to the material ratio of 1 mL: 60 μ L of: reacting 15 mu L in an oil bath at 90 ℃ for 2h, and evaporating ethanol to obtain the yellow electric field controllable structure discoloring liquid.

The yellow electric field controllable structure color-changing liquid can be used as a basic model of a rapid response traffic light under low voltage by combining with the embodiment 2, as shown in fig. 5.