Super-hydrophobic coating with blue-red light dual-emission performance and preparation method thereof

Abstract

The invention discloses a super-hydrophobic coating with blue-red light dual-emission performance. The coating is prepared from the following raw materials: a high-molecular polymer, a carbon quantum dot / layered silicate super-hydrophobic composite material, a curing agent, a silane coupling agent and a solvent, the carbon quantum dot / layered silicate super-hydrophobic composite material is obtained by carrying out hydrothermal reaction on layered silicate, a nonionic surfactant, organic acid and a nitrogen-containing and sulfur-containing organic compound, generating carbon quantum dots on the surface and between layers of the layered silicate in situ, and then carrying out low surface energy treatment by the nonionic surfactant to construct a micro-nano layered structure. The coating material disclosed by the invention is a composite material with blue-red light dual emission and super-hydrophobic performance, can break through the limitation of single function and poor durability of a traditional material, provides a brand new solution for agricultural dust prevention and efficiency improvement and optical energy optimization and utilization, and has important significance and wide prospects for promoting the development of intelligent agriculture.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical materials, and in particular relates to a super-hydrophobic coating with blue and red light dual-emission performance and a preparation method thereof. Background Art

[0002] Superhydrophobic materials have shown great application value in the field of agricultural dust prevention due to their excellent self-cleaning properties. At present, traditional superhydrophobic coatings mostly use nano-silica particles dispersed in a polymer substrate, or form a "micron hill-nanothorn" structure through metal oxide etching. Although some studies have attempted to enhance the stability of micro-nano structures through chemical bonding, they still face key technical bottlenecks: under long-term wind and sand erosion or mechanical friction, the surface roughness of the coating is easily damaged, causing the contact angle to rapidly decay from the initial 150° to below 140°, and the dustproof performance is greatly reduced; at the same time, the existing coating functions are relatively simple and can only achieve basic dustproof effects, which makes it difficult to meet the complex needs of modern agriculture for light energy spectrum regulation.

[0003] Carbon quantum dots (CQDs), as an emerging material with both nanostructure construction capabilities and optical tunability, bring new directions to the functional upgrade of superhydrophobic coatings. Although existing research can construct micro-nano structures such as nano-protrusions and porous networks by regulating the size or surface functional groups of carbon quantum dots, and realize single-band fluorescence emission of blue or red light, the synergistic integration of blue-red light dual emission and superhydrophobicity still faces severe challenges. The reason is that carbon quantum dots of different sizes are prone to phase separation due to differences in particle size during the composite process. This will not only lead to the agglomeration of luminescent units and destroy the uniformity of the micro-nano structure, but also cause structural defects, resulting in a significant reduction in superhydrophobic performance (the contact angle is often less than 150°). At the same time, the blue-red light emitting units are unevenly dispersed and the intensity ratio fluctuates violently, making it difficult to meet the needs of precise spectral control. Summary of the Invention

[0004] Purpose of the invention: The first purpose of the present invention is to provide a super-hydrophobic coating with blue-red light dual emission properties, to improve the hydrophobicity and the uniformity of red and blue light emission; the second purpose of the present invention is to provide a method for preparing the super-hydrophobic coating with blue-red light dual emission properties.

[0005] Technical solution: The super-hydrophobic coating with blue-red light dual-emission properties described in the present invention comprises: a high molecular weight polymer, a carbon quantum dot / layered silicate super-hydrophobic composite material, a curing agent, a silane coupling agent, and a solvent; wherein the carbon quantum dot / layered silicate super-hydrophobic composite material is hydrothermally reacted with layered silicate, a nonionic surfactant, an organic acid, and a nitrogen-containing and sulfur-containing organic compound to in-situ generate carbon quantum dots on the surface and between layers of the layered silicate, and then subjected to low surface energy treatment with a nonionic surfactant to construct a micro-nano layered structure.

[0006] Preferably, the mass ratio of the layered silicate, the organic acid and the nitrogen and sulfur containing organic compound is 0.1-0.9: 0.2-0.6: 0.1-0.4.

[0007] Preferably, the layered silicate is montmorillonite, talc or mica.

[0008] Preferably, the organic acid is citric acid, oxalic acid or lactic acid; the nitrogen and sulfur containing organic compound is methylthiourea, diethylthiourea or thiourea. The organic acid and the nitrogen and sulfur containing organic compound generate carbon quantum dots in the hydrothermal reaction process.

[0009] The non-ionic surfactant is a fluorine-containing non-ionic surfactant perfluoroalkyl alcohol polyoxyethylene ether, a fluorocarbon surfactant or a perfluoroalkyl polyether.

[0010] The solvent in the coating raw material is acetone.

[0011] Preferably, the ratio of the high molecular polymer, the carbon quantum dot / layered silicate super-hydrophobic composite material, the curing agent, the silane coupling agent and the solvent is 0.5-1.0 g: 0.03-0.2 g: 0.2-0.6 g: 0.05-0.35 g: 5-30 mL.

[0012] The high molecular polymer is a film-forming material. The silane coupling agent is a bridging agent, which reacts with the active functional groups on the high polymer matrix on one end and with the active functional groups on the curing agent on the other end. The curing agent makes the linear high polymer into a network high polymer. The three play a role in the process of preparing the coating, making the coating more firm and better in mechanical stability.

[0013] Preferably, the high molecular polymer is an epoxy resin, a phenolic resin or a polyurethane resin; the curing agent is a polyetheramine T403, a T5000 polyetheramine or a D230 polyetheramine.

[0014] Preferably, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane or γ-methacryloyloxypropyltrimethoxysilane.

[0015] The preparation method of the super-hydrophobic coating with blue and red light dual emission performance comprises the following steps:

[0016] Step one, dissolve the layered silicate, the non-ionic surfactant, the organic acid and the nitrogen and sulfur containing organic compound in the solvent, perform a solvothermal reaction, dry after the reaction is completed, and obtain a carbon quantum dot / layered silicate super-hydrophobic composite material with blue and red light dual emission performance;

[0017] Step 2: Mix the high molecular polymer, carbon quantum dot / layered silicate super-hydrophobic composite material, curing agent, and silane coupling agent in a solvent, mix them evenly, and then spray them on the surface of the substrate to form a super-hydrophobic dustproof coating.

[0018] Preferably, the temperature of the solvothermal reaction is 180 to 250° C. More preferably, the time of the solvothermal reaction is 5 to 15 hours.

[0019] Preferably, in step 1, the solvent is ethanol.

[0020] Preferably, in step 1, the drying is oven drying at a temperature of 50 to 80° C. for 10 to 15 hours.

[0021] Preferably, in step 1, the drying step further includes sieving, and the mesh size of the sieve is 100 to 200 meshes.

[0022] Preferably, in step 2, the solvent is acetone.

[0023] Invention Mechanism: This invention utilizes a solvothermal method to in-situ grow carbon quantum dots on the surface and between layers of layered silicates. This is then modified with a fluorinated nonionic surfactant to create a low-energy micro-nanostructure, resulting in a super-hydrophobic composite material with dual blue- and red-light emission properties. This composite is then cured with a polymer to create a long-lasting, super-hydrophobic, dust-proof coating with dual blue- and red-light emission properties.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The carbon quantum dots prepared by the present invention not only participate in the construction of micro-nanostructures to achieve super-hydrophobicity, but their intrinsic optical properties also give the coating the function of red and blue light emission. The material is a composite material with both blue and red light dual emission and super-hydrophobicity; the material has achieved a leap from "single dustproof" to "dustproof + optical regulation"; (2) The super-hydrophobic dustproof coating prepared by the present invention has excellent super-hydrophobicity, and its water contact angle is 168.5±3° and the rolling angle is 1.5±0.4°; (3) The super-hydrophobic dustproof coating prepared by the present invention exhibits excellent wear resistance due to its unique hierarchical micro-nanostructure. After 200 wear cycle tests, its water contact angle is still maintained at 158.2° and the rolling angle is 6.1°. The super-hydrophobicity remains stable, which is significantly better than traditional super-hydrophobic coatings; (4) The preparation method is simple and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a scanning electron microscope (SEM) image of the superhydrophobic material with blue-red light dual emission properties prepared in Example 1;

[0026] Figure 2 This is a photoluminescence (PL) emission spectrum of the superhydrophobic material with blue and red light dual emission properties prepared in Example 1;

[0027] Figure 3 1 is a photoluminescence (PL) emission spectrum of the superhydrophobic material synthesized in Comparative Example 1;

[0028] Figure 4 The water contact angle (WCA) and sliding angle (SA) of the superhydrophobic coating with blue-red dual emission properties prepared in Example 1;

[0029] Figure 5 This is a picture of a water droplet bouncing on the super-hydrophobic coating with blue-red light dual-emission properties prepared in Example 1;

[0030] Figure 6 This is a self-cleaning analysis diagram of the super-hydrophobic coating with blue-red light dual-emission performance prepared in Example 1;

[0031] Figure 7 This is a graph showing the changes in WCA and SA during mechanical reciprocating wear of the superhydrophobic coating with blue-red light dual-emission properties prepared in Example 1 under a load of 200 g;

[0032] Figure 8 This is a graph showing the changes in WCA and SA during mechanical reciprocating wear of the superhydrophobic coating synthesized in Comparative Example 1 under a load of 200 g. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be further described below in conjunction with embodiments.

[0034] Example 1

[0035] The super-hydrophobic coating with blue-red light dual-emission performance of the present invention comprises the following steps:

[0036] Step 1: Dissolve 0.46g of montmorillonite, 0.34g of perfluoroalkylethanol polyoxyethylene ether, 0.2g of citric acid, and 0.34g of thiourea in 60mL of ethanol, then transfer to a Teflon autoclave and heat at 200°C for 8h. The heated mixed suspension is dried in a 70°C oven for 12h and passed through a 100-mesh sieve to obtain a montmorillonite / carbon quantum dot superhydrophobic composite material with blue and red dual emission properties (denoted as CDs / MMT);

[0037] Step 2: Premix 0.9 g of epoxy resin, 0.1 g of carbon quantum dots / montmorillonite superhydrophobic composite material, 0.3 g of polyetheramine T403, and 0.1 g of γ-glycidyloxypropyltrimethoxysilane in 20 mL of acetone solvent. After mechanical stirring, the mixed suspension is sprayed on the surface of the pretreated glass plate with a spray gun to form a superhydrophobic coating with blue and red light dual emission properties (denoted as ER-CDs / MMT).

[0038] Example 2

[0039] Step 1: Dissolve 0.1g of talc, 0.1g of perfluoroalkyl polyether, 0.2g of citric acid, and 0.1g of diethylthiourea in 20mL of ethanol, transfer to a Teflon autoclave, and heat at 200°C for 8h. The heated mixed suspension is dried in a 70°C oven for 11h and passed through a 100-mesh sieve to obtain a carbon quantum dot / talc superhydrophobic composite with blue-red dual-emission properties.

[0040] Step 2: Pre-mix 0.5g of phenolic resin, 0.03g of carbon quantum dot / talc super-hydrophobic composite material, 0.2g of curing agent, and 0.05g of γ-aminopropyltriethoxysilane in 5mL of acetone solvent. After mechanical stirring, the mixed suspension is sprayed on the surface of the pretreated glass plate with a spray gun to form a super-hydrophobic dust-proof coating with blue and red light dual emission properties.

[0041] Example 3

[0042] Step 1: Dissolve 0.43g of montmorillonite, 0.4g of perfluoroalkylethanol polyoxyethylene ether, 0.275g of citric acid, and 0.3g of thiourea in 50mL of ethanol, transfer to a Teflon autoclave, and heat at 195°C for 10 hours. The heated mixed suspension is dried in a 70°C oven for 12 hours and passed through a 100-mesh sieve to obtain a carbon quantum dot / montmorillonite superhydrophobic composite with blue-red dual-emission properties.

[0043] Step 2: 0.94g epoxy resin, 0.1g carbon quantum dot / montmorillonite superhydrophobic composite material, 0.35g D230 polyetheramine, and 0.1g γ-methacryloxypropyltrimethoxysilane are pre-mixed in 25mL acetone solvent, mechanically stirred evenly, and then the mixed suspension is sprayed on the surface of the pretreated glass plate with a spray gun to form a superhydrophobic dust-proof coating with blue-red light dual emission performance.

[0044] Example 4

[0045] Step 1: Dissolve 0.9g of montmorillonite, 0.7g of perfluoroalkylethanol polyoxyethylene ether, 0.6g of lactic acid, and 0.4g of methylthiourea in 70mL of ethanol, transfer to a Teflon autoclave, and heat at 200°C for 8h. The heated mixed suspension is dried in a 70°C oven for 12h and passed through a 100-mesh sieve to obtain a carbon quantum dot / montmorillonite superhydrophobic composite with blue and red dual-emission properties.

[0046] Step 2: Pre-mix 1.0 g of polyurethane resin, 0.2 g of carbon quantum dot / montmorillonite superhydrophobic composite material, 0.6 g of T5000 polyetheramine, and 0.35 g of γ-glycidyloxypropyltrimethoxysilane in 30 mL of acetone solvent. After mechanical stirring, the mixed suspension is sprayed on the surface of the pretreated glass plate with a spray gun to form a superhydrophobic dust-proof coating with blue and red light dual emission properties.

[0047] Comparative Example 1

[0048] Step 1: Dissolve 0.2g of citric acid and 0.34g of thiourea in 60mL of ethanol, then transfer to a Teflon autoclave, heat at 200°C for 8h, centrifuge to separate large particles, freeze-dry the supernatant in a vacuum oven to obtain blue fluorescent carbon quantum dots, and dissolve the carbon quantum dots in deionized water to obtain a carbon quantum dot solution.

[0049] Step 2: Add 0.34g of perfluoroalkylethanol polyoxyethylene ether and 0.46g of montmorillonite to 5g of carbon quantum dot solution (carbon quantum dot mass is 0.05g), the temperature is 60°C, reflux stirring, stirring for 12 hours, and the speed is 500r / min. The solution is placed in an oven to dry (temperature: 50°C, time: 24h), and ground through a 100-mesh sieve to obtain a carbon quantum dot / montmorillonite superhydrophobic composite material.

[0050] Step three, pre-mix 0.9g epoxy resin, 0.1g carbon quantum dot / montmorillonite superhydrophobic composite material, 0.3g polyetheramine T403, and 0.1g γ-glycidyloxypropyltrimethoxysilane in 20mL acetone solvent, stir mechanically until evenly, and spray the mixed suspension on the surface of the pretreated glass plate with a spray gun to form a superhydrophobic dust-proof coating.

[0051] Structural characterization

[0052] The structure of the super hydrophobic composite material CDs / MMT prepared in Example 1 was characterized, and the results were as follows: Figures 1 to 3 shown.

[0053] like Figure 1 As shown, carbon quantum dots are in situ grown on the surface and between layers of montmorillonite, together constructing a rough micro-nano structure.

[0054] Performance Testing

[0055] 1. Fluorescence performance test of superhydrophobic composite materials

[0056] The fluorescence emission spectra of the super-hydrophobic composite materials prepared in Example 1 and Comparative Example 1 were tested, and the results were as follows: Figure 2 and 3 shown.

[0057] like Figure 2As shown, the photoluminescence (PL) spectrum shows multiple fixed down-conversion fluorescence emission peaks at 498 nm, 593 nm and 657 nm, indicating that the CDs / MMT superhydrophobic composite material can achieve blue and red dual emission.

[0058] like Figure 3 As shown, the photoluminescence (PL) spectrum of the super-hydrophobic composite material synthesized in Comparative Example 1 shows obvious fluorescence only in the blue light range, and the fluorescence spectrum in the red light range is weak, and its fluorescence performance is not as good as that in Example 1. This is mainly because the carbon quantum dots can be evenly dispersed during the one-step synthesis in Example 1, which reduces the generation of fluorescence quenching. Therefore, the super-hydrophobic composite material synthesized in Example 1 has excellent fluorescence properties.

[0059] 2. Contact angle and rolling angle test

[0060] Test method: This experiment uses the SDA30S fully automatic contact angle meter from KRUSSG, Germany, to test the water static contact angle (WCA) and dynamic contact angle (SA) of the coating. 4 μL of deionized water is used for each test. Each sample is tested 3 to 5 times, and the average value is taken.

[0061] The test results are as follows Figure 4 shown.

[0062] like Figure 4 As shown, the water contact angle of the ER-CDs / MMT prepared in Example 1 was 168.5±3°, and the sliding angle was 1.5±0.4°, showing excellent superhydrophobic properties.

[0063] 3. Water drop bouncing test on coating surface

[0064] Test method: This experiment uses the SDA30S fully automatic contact angle meter from the German KRUSSG company to test the coating's bounce performance. For each test, 10 μL of deionized water is naturally dripped onto the surface of the super-hydrophobic coating and the dynamic image is observed. Figure 5 shown.

[0065] like Figure 5 As shown, a water droplet successfully bounced off the ER-CDs / MMT coating prepared in Example 1 three times within 170 ms. Even after the superhydrophobic surface was compressed by the needle tip, the droplet remained suspended, demonstrating the coating's ultra-low adhesion to the droplet. These properties are attributed to the resiliency achieved by squeezing air trapped within the micro-nano hierarchical structure and low-surface-energy molecules, resulting in the coating exhibiting exceptional superhydrophobicity and low adhesion properties.

[0066] 4. Coating self-cleaning performance test

[0067] Test method: Place the sample sprayed with the coating in a watch glass at an angle of 40°, place 1g of sediment in the center of the lower surface of the coating, use a rubber-tipped dropper to naturally drip water, and observe the removal of the sediment on the surface. Figure 6 shown.

[0068] like Figure 6 As shown, the self-cleaning properties of the ER-CDs / MMT coating prepared in Example 1 were evaluated using quartz sand as the contaminant. Because the coating has a rolling angle of only 1.5 ± 0.4°, a water droplet applied to the surface easily rolls into a spherical shape and collects contaminants under the influence of gravity. When the water droplet lands on the contaminated surface, it quickly rolls away the contaminants, restoring a clean surface.

[0069] 5. Coating wear resistance test

[0070] Test method: Place the glass sheet sprayed with ER-CDs / MMT coating face down on 600-grit sandpaper, place a 200g weight on the back of the glass sheet, and drag the glass sheet to perform the wear test. One cycle is forward (10cm) and backward (10cm) at a uniform speed. Measure the WCA and SA values ​​every 20 cycles. Test results are as follows: Figure 7 and Figure 8 shown.

[0071] like Figure 7 As shown in Figure 1, a sample spray-coated with CDs / MMT prepared in Example 1 was placed face-down on 600-grit standard sandpaper with a 200-g load and moved 20 cm for one abrasion cycle. After 200 abrasion cycles, the coating still exhibited excellent superhydrophobicity, with a water contact angle of 158.2° and a sliding angle of 6.1°. This robust superhydrophobicity can be attributed to the hierarchical stacking of CDs / MMT on the surface. As the top filler wears away, the next level of filler is exposed, ensuring the coating maintains its sustained superhydrophobicity.

[0072] like Figure 8 Shown, the sample face of the super-hydrophobic composite material synthesized in spraying comparative example 1 is placed on 600 mesh standard sandpaper, and load is 200g, and moves the distance of 20cm to carry out a wear cycle.Only after 100 wear cycles, coating is rapidly reduced to WCA of 138.2 °, SA>10 ° from the WCA=159.1 ° at the beginning, SA=3.9 °. It can be seen that the super-hydrophobicity of the coating is weaker than Example 1, and the wear resistance of the coating is poor, this is mainly because one pot method is taken to synthesize super-hydrophobic composite material in Example 1, it is possible to ensure that more nano-scale carbon point in-situ growth is in micron-level montmorillonite surface or interlayer, multi-level micro-nano rough structure can be formed, when the wear of top filler, next level filler can be exposed, so as to ensure that coating maintains continuous super-hydrophobicity.

Claims

1. A super-hydrophobic coating with blue-red light dual emission performance, characterized in that: The coating raw materials include: a high molecular weight polymer, a carbon quantum dot / layered silicate super-hydrophobic composite material, a curing agent, a silane coupling agent and a solvent; wherein the carbon quantum dot / layered silicate super-hydrophobic composite material is obtained by hydrothermal reaction of layered silicate, a nonionic surfactant, an organic acid and a nitrogen-containing and sulfur-containing organic compound, in situ generating carbon quantum dots on the surface and between layers of the layered silicate, and then undergoing low surface energy treatment with a nonionic surfactant to construct a micro-nano layered structure.

2. The super-hydrophobic coating with blue-red light dual emission performance according to claim 1, wherein The mass ratio of the layered silicate, the organic acid and the nitrogen-containing and sulfur-containing organic compound is 0.1-0.9:0.2-0.6:0.1-0.

4.

3. The super-hydrophobic coating with blue-red light dual emission performance according to claim 1, characterized in that The layered silicate is montmorillonite, talc or mica.

4. The super-hydrophobic coating having blue-red light dual emission performance according to claim 1, wherein The organic acid is citric acid, oxalic acid or lactic acid; the nitrogen-containing and sulfur-containing organic compound is methylthiourea, diethylthiourea or thiourea.

5. The super-hydrophobic coating having blue-red light dual emission performance according to claim 1, characterized in that: The usage ratio of the high molecular polymer, carbon quantum dot / layered silicate super-hydrophobic composite material, curing agent, silane coupling agent and solvent is 0.5-1.0 g: 0.03-0.2 g: 0.2-0.6 g: 0.05-0.35 g: 5-30 mL.

6. The super-hydrophobic coating with blue-red light dual emission performance according to claim 1, characterized in that: The high molecular polymer is epoxy resin, phenolic resin or polyurethane resin; the curing agent is polyetheramine T403, T5000 polyetheramine or D230 polyetheramine.

7. The super-hydrophobic coating with blue-red light dual emission performance according to claim 1, characterized in that: The silane coupling agent is γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane or γ-methacryloxypropyltrimethoxysilane.

8. The super-hydrophobic coating with blue-red light dual emission performance according to claim 1, characterized in that: The nonionic surfactant is a fluorine-containing nonionic surfactant perfluoroalkylethanol polyoxyethylene ether, a fluorocarbon surfactant or a perfluoroalkyl polyether.

9. A method for preparing a super-hydrophobic coating having blue-red light dual emission properties according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: dissolving a layered silicate, a fluorine-containing nonionic surfactant, an organic acid, and a nitrogen-containing and sulfur-containing organic compound in a solvent, performing a solvothermal reaction, and drying after the reaction to obtain a carbon quantum dot / layered silicate superhydrophobic composite material with blue-red light dual emission properties; Step 2: Mix the high molecular polymer, carbon quantum dot / layered silicate super-hydrophobic composite material, curing agent, and silane coupling agent in a solvent, mix them evenly, and then spray them on the surface of the substrate to form a super-hydrophobic dustproof coating.

10. The method for preparing a super-hydrophobic coating having blue-red light dual emission performance according to claim 9, wherein: The temperature of the solvent thermal reaction is 180-250°C.

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