Preparation method of photo-thermal anti-icing / deicing slurry, photo-thermal anti-icing / deicing slurry and application

Abstract

The invention discloses a preparation method of photo-thermal anti-icing / deicing slurry, the photo-thermal anti-icing / deicing slurry and application. The preparation method comprises the following steps: in the presence of a basic catalyst, mixing an aqueous dispersion of nanocellulose with a polymer-based photo-thermal material monomer for reaction to obtain a first mixed solution; and mixing the first mixed solution with a water repellent agent solution, carrying out a grafting reaction, and carrying out centrifugal washing to obtain the photo-thermal anti-icing / deicing slurry. After the slurry prepared by the method is used for forming a coating, the problem that an anti-freezing surface is difficult to maintain an anti-freezing state in a long-time use state or a low-temperature and high-humidity environment can be well solved, and in addition, the coating can realize anti-icing and deicing, water and water proofing, thermal management, ultraviolet radiation prevention, photo-thermal sterilization, oil-water separation and the like of a solid surface.

Description

Technical Field

[0001] The present invention relates to the field of photothermal anti-icing. More specifically, it relates to a preparation method of a photothermal anti-icing / de-icing slurry, a photothermal anti-icing / de-icing slurry and applications thereof. Background Art

[0002] Ice formation is a common phenomenon in nature. However, in some cases, icing and ice accretion on surfaces can cause serious property losses and even endanger human lives. Icing on traffic roads can lead to slippery road surfaces and traffic accidents; icing on the surfaces of new energy sources such as wind turbine blades and solar cells will reduce their energy conversion efficiency; icing on transmission lines and transmission tower surfaces will increase power consumption and increase the surface load weight, and in severe cases, it will cause large-scale power outages due to falling and breaking; icing on the aircraft surface will affect the aerodynamic shape and reduce the operational stability. The traditional de-icing methods currently used mainly include electrothermal de-icing, chemical anti-icing, mechanical de-icing, etc. These methods not only have complex and expensive equipment, but also consume a large amount of energy and pollute the environment. Melting ice and removing ice by converting sunlight into heat based on photothermal materials is undoubtedly more economical and environmentally friendly.

[0003] Recently, anti-icing surfaces that suppress surface icing and reduce ice adhesion by regulating surface properties have attracted the attention of researchers. Compared with traditional de-icing methods, anti-icing surfaces have the advantages of low cost, low energy consumption, environmental friendliness and easy implementation. They mainly include superhydrophobic surfaces that mimic lotus leaves (contact angle greater than 150°, rolling angle less than 10°), super-slippery surfaces that mimic Nepenthes, and biomimetic antifreeze protein (AFPs) surfaces. Among them, the non-wetting and self-cleaning superhydrophobic surface can weaken the heat exchange between water droplets and the surface through the air layer and remove water droplets in time through the self-cleaning ability to inhibit icing; the super-slippery surface can greatly reduce the adhesion force of water droplets or ice cubes by injecting lubricating liquids into the porous microstructures, making de-icing easier; the biomimetic antifreeze protein surface can control the properties of interfacial water and inhibit icing by regulating the hydrophobic and hydrophilic parts. However, if these anti-icing surfaces are in a long-term use state or in a low-temperature and high-humidity environment, their surfaces will eventually ice up and fail.

[0004] Therefore, the composite anti-icing / de-icing surface combining the novel anti-icing surface and the photothermal material is an important direction for future development. At present, the preparation of the composite anti-icing surface mainly disperses the photothermal material in the superhydrophobic coating, that is, uses nano materials such as carbon, metal or metal oxide to jointly construct the rough surface of the superhydrophobic coating, and then performs low surface energy modification. However, these preparation methods are usually cumbersome, require a large amount of toxic organic solvents, fluorine-containing and silicon-containing substances, and are harmful to the human body and the environment. In addition, metal nano materials themselves also have toxicity and structural instability, and carbon materials often show poor solution processability due to the lack of surface functional groups. When they are compounded with the polymer matrix, agglomeration will occur due to weak interfacial interaction, which is not conducive to the mechanical stability and photothermal performance of the coating. Polymer photothermal materials such as polypyrrole, polythiophene and polydopamine and their derivatives have the advantages of molecular level structure design, good solution processability, strong light absorption, high photothermal conversion efficiency and biocompatibility. They can simplify the preparation process while ensuring the photothermal performance and have good biocompatibility. As the most abundant biological material on the earth, nanocellulose has the advantages of rich sources, good biocompatibility, excellent mechanical properties, high aspect ratio, large specific surface area, and rich surface hydroxyl groups, which are easy to modify. Based on these advantages, there are many studies on using it for hydrophobic modification and preparing superhydrophobic surfaces. However, there are almost no further studies on using it to prepare anti-icing surfaces. It should be noted that superhydrophobic surfaces are often different from anti-icing surfaces. Appropriate microstructures and low surface energy substances can greatly reduce the solid-liquid contact area and act as a thermal barrier by capturing the air layer, thereby reducing the solid-liquid heterogeneous nucleation rate and achieving the effect of delaying ice formation; while inappropriate structures will greatly reduce the anti-icing performance, and even promote ice nucleation instead. Summary of the Invention

[0005] Based on the above facts, the purpose of the present invention is to provide a preparation method of a photothermal anti-icing slurry, a photothermal anti-icing / de-icing slurry and its application, so as to solve the problem that the anti-icing surface is difficult to maintain the anti-icing state during long-term use or in a low temperature and high humidity environment. In addition, the coating can achieve anti-icing and de-icing of solid surfaces, waterproof and hydrophobic, thermal management, anti-ultraviolet irradiation, photothermal sterilization and oil-water separation, etc.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] On the one hand, the present invention provides a preparation method of a photothermal anti-icing / de-icing slurry, and the preparation method includes the following steps:

[0008] In the presence of an alkaline catalyst, mix and react an aqueous dispersion of nanocellulose with a polymer-based photothermal material monomer to obtain a first mixed solution;

[0009] After mixing the first mixture with the hydrophobic agent solution, a grafting reaction is carried out and centrifugal washing is performed to obtain the photothermal anti-icing / de-icing slurry.

[0010] In this preparation method, in the reaction for preparing the first mixture, the polymer-based photothermal material monomer polymerizes on the surface of nanocellulose to obtain the polymer-based photothermal material, which is coated on the surface of nanocellulose. This method overcomes the drawbacks of the existing coating method, which mostly immerses the solid surface in the aqueous solution of the polymer-based photothermal material monomer for dip coating. However, the dip coating method has disadvantages such as the substrate size being limited by the container, the coating thickness being difficult to control, and it being unfavorable for subsequent hydrophobic modification. At the same time, this preparation method overcomes the common drawbacks of conventional anti-icing surfaces: after long-term use or in a low-temperature and high-humidity environment, ice will eventually form on its surface and it will fail.

[0011] Furthermore, the addition amount of the alkaline catalyst is controlled to make the aqueous dispersion of nanocellulose weakly alkaline.

[0012] Furthermore, the pH of the mixture of the alkaline catalyst and the aqueous dispersion of nanocellulose is 8 - 12, preferably 7 - 9.

[0013] Furthermore, the concentration of the aqueous dispersion of nanocellulose is (0.3 - 0.5) g / 100 ml.

[0014] Furthermore, the aqueous dispersion of nanocellulose is prepared by the following method:

[0015] The aqueous dispersion of nanocellulose with a mass concentration of 0.1% - 10%, preferably 1% - 3%, is ultrasonically dispersed in deionized water to obtain it; wherein, the volume of deionized water is 50 - 200 ml, and an example is 100 ml.

[0016] Furthermore, the ultrasonic dispersion is carried out by an ultrasonic probe of a cell disruptor, with a power of 100 - 1000 W, and examples are 300 W, 400 W, 500 W. Furthermore, the ultrasonic dispersion time is 1 - 10 min, and examples are 4 min, 5 min, 6 min.

[0017] Furthermore, in the aqueous dispersion of nanocellulose, the diameter of nanocellulose is 1 - 100 nm, preferably 2 - 20 nm; the length of nanocellulose is 10 - 300 μm, preferably 30 - 200 μm.

[0018] Furthermore, in the aqueous dispersion of nanocellulose, the nanocellulose is lignocellulose, and the mass percentage content of lignin in this lignocellulose is 1.99%, and the diameter is 4.6 ± 1.9 nm.

[0019] Further, the alkaline catalyst is selected from one of sodium hydroxide, potassium hydroxide, and tris(hydroxymethyl)aminomethane.

[0020] Further, the monomer of the polymer-based photothermal material is selected from one of pyrrole, dopamine, thiophene, and aniline, and preferably dopamine.

[0021] Further, the mass ratio of the nanocellulose to the monomer of the polymer-based photothermal material is 1:(0.2 - 2), and preferably 1:(0.6 - 1.5). Too much or too little amount of the monomer of the polymer-based photothermal material will affect the subsequent grafting reaction and the photothermal performance of the coating.

[0022] Further, the mixing reaction is carried out at room temperature, and the time of the mixing reaction is preferably 12 - 36 h.

[0023] Further, in the hydrophobic agent solution, the hydrophobic agent is selected from at least one of octadecylamine, octadecanethiol, polytetrafluoroethylene, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, polyhedral oligomeric silsesquioxane, polydimethylsiloxane, and octadecyltrimethoxysilane.

[0024] Further, in the hydrophobic agent solution, the solvent is selected from one or more of ethyl acetate, ethanol, N,N-dimethylformamide (DMF), and toluene.

[0025] Further, the mass ratio of the nanocellulose to the hydrophobic agent is 1:(0.5 - 5), and preferably 1:(0.5 - 4.5).

[0026] Further, the temperature of the grafting reaction is 25 - 70 °C, and the time is 12 - 36 h. The preferred temperature of the grafting reaction is 45 - 55 °C, more preferably 50 - 55 °C, and the preferred time of the grafting reaction is 20 - 30 h.

[0027] Further, the centrifugal washing is carried out by a centrifuge, the rotation speed is 5000 - 10000 rpm, and exemplarily 6000 rpm, 70000 rpm, 80000 rpm. Further, the centrifugal time is 5 - 30 min, and exemplarily 10 min, 15 min, 20 min.

[0028] Further, the above mixing is stirring mixing. For example, the stirring rate of the stirring mixing is 100 - 1000 rpm, preferably 400 - 800 rpm, and exemplarily 500 rpm.

[0029] In the second aspect, the present invention provides a photothermal anti-icing / de-icing slurry, which is prepared by the preparation method described in the first aspect above.

[0030] In a third aspect, the present invention provides a photothermal anti-icing / de-icing coating, which is obtained by coating the photothermal anti-icing / de-icing slurry prepared by the preparation method described in the first aspect or the photothermal anti-icing / de-icing slurry described in the second aspect on a substrate and drying it.

[0031] Furthermore, the drying temperature is 25-120°C, such as 25-100°C.

[0032] In this technical solution, after the slurry is applied, it can be quickly dried and formed at room temperature. Exemplarily, the drying time is 1-20 minutes, such as 5-15 minutes, 10 minutes, etc.

[0033] Furthermore, the substrate is selected from paper products, fabrics, glass or ceramic products.

[0034] Furthermore, the coating method includes but is not limited to scraping, spraying, spin coating, etc.

[0035] Furthermore, the coating amount of the photothermal anti-icing / de-icing coating is 1-30g / m 2 Exemplary coating amounts include, but are not limited to, 1-30 g / m 2 , 10-30g / m 2 , 10-20g / m 2 , 15-30g / m 2 , 15-20g / m 2 , 15-20g / m 2 wait.

[0036] Furthermore, the dry film thickness of the photothermal anti-icing / de-icing coating is 25-40 microns, preferably 25-35 microns, 30-35 microns, etc.

[0037] In a fourth aspect, the present invention provides the use of the photothermal anti-icing / de-icing slurry prepared by the preparation method described in the first aspect or the photothermal anti-icing / de-icing slurry described in the second aspect in the coating of paper products, fabrics, glass or ceramic products.

[0038] Furthermore, the photothermal anti-icing / de-icing slurry is used for coating glass, aluminum sheets, paper, wood or fabric.

[0039] The beneficial effects of the present invention are as follows:

[0040] After the photothermal anti-icing / de-icing slurry prepared by the preparation method of the present invention is coated on a substrate to form a coating, the obtained coating can achieve the functions of self-cleaning, delayed icing and de-icing; the coating has excellent ultraviolet absorption ability and can be applied to ultraviolet protection; the coating has excellent photothermal conversion ability and can rapidly heat up under the irradiation of light with a solar intensity of 1 sun (1000 W / ㎡). Specifically, the coating mainly realizes the superhydrophobic photothermal function in the following ways: a. Nanocellulose has a high aspect ratio and is easy to construct the multi-level micro-nano structure required for a superhydrophobic coating; b. The formed polymer-based photothermal material is coated on the nanocellulose through hydrogen bonds to endow the coating with photothermal ability; c. The hydrophobic agent undergoes a grafting reaction with the polymer-based photothermal material to reduce the surface energy of the coating and endow the coating with superhydrophobic properties.

[0041] In the preparation method of the photothermal anti-icing / de-icing slurry provided by the present invention, the raw materials used are biomass materials, the hydrophobic agent used is a non-toxic substance, and the solvent used is also environmentally friendly, without the need for cumbersome wastewater treatment procedures; no waste is generated during the whole preparation process, solving the problem of environmental pollution of the existing anti-icing / de-icing coatings; in addition, the process is simple and only requires step-by-step stirring and mixing of the materials, without special treatments such as high temperature and high pressure. Description of the Drawings

[0042] The following further details the specific embodiments of the present invention with reference to the drawings.

[0043] Figure 1 Show the static water contact angle image on the surface of the coating prepared in Example 1.

[0044] Figure 2 Show the scanning electron microscope image on the surface of the coating prepared in Example 1.

[0045] Figure 3 Show the transmittance and reflectance of the coatings prepared in Example 1 (3ODA-PDA@CNF), Comparative Example 1 (PDA@CNF), Comparative Example 2 (CNF / ODA) and the glass slide (GLASS) in the ultraviolet-visible-infrared band.

[0046] Figure 4 Show the change of the surface temperature of the coatings prepared in Example 1 (3ODA-PDA@CNF), Comparative Example 1 (PDA@CNF) and the glass slide (GLASS) with time under the irradiation of one sun intensity.

[0047] Figure 5 Show the icing time and state of water droplets on the surface of the coatings prepared in Example 1 (3ODA-PDA@CNF), Comparative Example 1 (PDA@CNF) and the glass slide (GLASS) at -15°C.

[0048] Figure 6 Show the ice formation time and state of the water droplets on the surface of the coating prepared in Example 1 at -30 °C under sunlight irradiation.

[0049] Figure 7 Show the ice formation time and state of the water droplets on the surface of the coating prepared in Example 1 under different temperatures and sunlight irradiation.

[0050] Figure 8 Show the melting conditions of the surfaces of Example 1 (3ODA - PDA@CNF), Comparative Example 1 (PDA@CNF), and the glass slide (GLASS) that were pre - frozen by ice cubes and then irradiated by sunlight. Detailed implementation mode

[0051] To illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments and drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0052] Example 1

[0053] A method for preparing a nanocellulose - based photothermal anti - icing / de - icing slurry, specifically including the following steps:

[0054] 1) Take 21.05 g of an aqueous dispersion of nanocellulose with a mass fraction of 1.9 wt% (in this aqueous dispersion, the diameter of the nanocellulose is 2 - 20 nm and the length is 30 - 200 μm), pour it into deionized water and dilute it to 100 ml;

[0055] 2) Use an ultrasonic cell disruptor to ultrasonically disperse the nanocellulose until it is evenly dispersed;

[0056] 3) Add 0.12 g of tris (hydroxymethyl) aminomethane to the nanocellulose dispersion and adjust the nanocellulose dispersion to weakly alkaline (pH about 8.5);

[0057] 4) Add 0.4 g of dopamine to the weakly alkaline nanocellulose dispersion, and stir at room temperature for 24 h to form a first mixed solution;

[0058] 5) Take 1.2 g of octadecylamine in ethanol, stir at 50 °C until dissolved, then pour it into the first mixed solution and continue to stir for 24 h to form a second mixed solution;

[0059] 6) Centrifuge and wash the second mixed solution with ethanol several times to remove the unreacted dopamine and octadecylamine, and obtain the photothermal anti - icing / de - icing slurry.

[0060] A method for preparing a nanocellulose - based photothermal anti - icing / de - icing coating, including the following steps:

[0061] Pour the obtained photothermal anti-icing / de-icing slurry into a spray gun and spray it on a glass substrate. After drying at room temperature, a coating with a coating amount of about 16 g / m 2 is obtained.

[0062] Examples 2-8

[0063] Same as Example 1, the difference is that: in step 5), the amounts of octadecylamine are 0.4 g, 0.6 g, 0.8 g, 1.0 g, 0.2 g, 1.4 g, and 1.6 g respectively.

[0064] Example 9

[0065] A method for preparing a nanocellulose-based photothermal anti-icing / de-icing slurry, specifically comprising the following steps:

[0066] 1) Take 21.05 g of an aqueous dispersion of nanocellulose with a mass fraction of 1.9 wt% (in this aqueous dispersion, the diameter of the nanocellulose is 2-20 nm and the length is 30-200 μm), pour it into deionized water and dilute it to 100 ml;

[0067] 2) Use an ultrasonic cell disruptor to ultrasonically disperse the nanocellulose until it is evenly dispersed;

[0068] 3) Add tris(hydroxymethyl)aminomethane to the nanocellulose dispersion to adjust the nanocellulose dispersion to weakly alkaline (pH about 8.5);

[0069] 4) Add 0.24 g of dopamine to the weakly alkaline nanocellulose dispersion, stir at room temperature for 24 h to form a first mixed solution;

[0070] 5) Take 0.72 g of octadecylamine in ethanol, stir at 50 °C until dissolved, then pour it into the first mixed solution and continue to stir for 24 h to form a second mixed solution;

[0071] 6) Centrifuge and wash the second mixed solution several times with ethanol to remove the unreacted dopamine and octadecylamine to obtain the photothermal anti-icing / de-icing slurry.

[0072] A method for preparing a nanocellulose-based photothermal anti-icing / de-icing coating, comprising the following steps:

[0073] Pour the photothermal anti-icing / de-icing slurry into a spray gun and spray it on a glass substrate. After drying at room temperature, a coating with a coating amount of about 16 g / m 2 is obtained.

[0074] Example 10

[0075] A method for preparing a nanocellulose-based superhydrophobic photothermal anti-icing / de-icing coating, specifically comprising the following steps:

[0076] 1) Take 21.05 g of an aqueous dispersion of nanocellulose with a mass fraction of 1.9 wt% (in this aqueous dispersion, the diameter of the nanocellulose is 2 - 20 nm and the length is 30 - 200 μm), pour it into deionized water and dilute it to 100 ml;

[0077] 2) Ultrasonically disperse the nanocellulose with an ultrasonic cell disruptor until it is uniformly dispersed;

[0078] 3) Add tris(hydroxymethyl)aminomethane to the nanocellulose dispersion to adjust the nanocellulose dispersion to weakly alkaline (pH about 8.5);

[0079] 4) Add 0.32 g of dopamine to the weakly alkaline nanocellulose dispersion, and stir at room temperature for 24 h to form a first mixture;

[0080] 5) Take 0.96 g of octadecylamine in ethanol, stir at 50 °C until dissolved, then pour it into the first mixture and continue to stir for 24 h to form a second mixture;

[0081] 6) Centrifuge and wash the second mixture with ethanol several times to remove the unreacted dopamine and octadecylamine, and obtain the photothermal anti-icing / de-icing slurry.

[0082] A method for preparing a nanocellulose-based photothermal anti-icing / de-icing coating, comprising the following steps:

[0083] Pour the photothermal anti-icing / de-icing slurry into a spray gun, spray it on a glass substrate, and dry it at room temperature to obtain a coating with a coating amount of about 16 g / m 2 of the coating.

[0084] Example 11

[0085] A method for preparing a nanocellulose-based superhydrophobic photothermal anti-icing / de-icing coating, specifically comprising the following steps:

[0086] 1) Take 21.05 g of an aqueous dispersion of nanocellulose with a mass fraction of 1.9 wt% (in this aqueous dispersion, the diameter of the nanocellulose is 2 - 20 nm and the length is 30 - 200 μm), pour it into deionized water and dilute it to 100 ml;

[0087] 2) Ultrasonically disperse the nanocellulose with an ultrasonic cell disruptor until it is uniformly dispersed;

[0088] 3) Add tris(hydroxymethyl)aminomethane to the nanocellulose dispersion to adjust the nanocellulose dispersion to weakly alkaline (pH about 8.5);

[0089] 4) Add 0.48 g of dopamine to the weakly alkaline nanocellulose dispersion, and stir at room temperature for 24 h to form a first mixture;

[0090] 5) Take 1.44 g of octadecylamine and dissolve it in ethanol. Stir at 50 °C until dissolved, then pour it into the first mixed solution and continue stirring for 24 h to form a second mixed solution.

[0091] 6) Centrifuge and wash the second mixed solution with ethanol several times to remove unreacted dopamine and octadecylamine, obtaining the photothermal anti-icing / de-icing slurry.

[0092] A method for preparing a nanocellulose-based photothermal anti-icing / de-icing coating, comprising the following steps:

[0093] Pour the photothermal anti-icing / de-icing slurry into a spray gun and spray it on a glass substrate. After drying at room temperature, a coating with a coating amount of about 16 g / m 2 is obtained.

[0094] Example 12

[0095] A method for preparing a nanocellulose-based superhydrophobic photothermal anti-icing / de-icing coating specifically comprises the following steps:

[0096] 1) Take 21.05 g of an aqueous dispersion of nanocellulose with a mass fraction of 1.9 wt% (in this aqueous dispersion, the diameter of the nanocellulose is 2 - 20 nm and the length is 30 - 200 μm), pour it into deionized water and dilute it to 100 ml.

[0097] 2) Use an ultrasonic cell disruptor to ultrasonically disperse the nanocellulose until it is uniformly dispersed.

[0098] 3) Add tris(hydroxymethyl)aminomethane to the nanocellulose dispersion to adjust the nanocellulose dispersion to be weakly alkaline (pH about 8.5).

[0099] 4) Add 0.56 g of dopamine to the weakly alkaline nanocellulose dispersion and stir at room temperature for 24 h to form a first mixed solution.

[0100] 5) Take 1.68 g of octadecylamine and dissolve it in ethanol. Stir at 50 °C until dissolved, then pour it into the first mixed solution and continue stirring for 24 h to form a second mixed solution.

[0101] 6) Centrifuge and wash the second mixed solution with ethanol several times to remove unreacted dopamine and octadecylamine, obtaining the photothermal anti-icing / de-icing slurry.

[0102] A method for preparing a nanocellulose-based photothermal anti-icing / de-icing coating, comprising the following steps:

[0103] Pour the photothermal anti-icing / de-icing slurry into a spray gun and spray it on a glass substrate. Dry at room temperature to obtain a coating with a coating amount of about 16 g / m 2 is obtained.

[0104] Comparative Example 1

[0105] This comparative example provides a photothermal slurry and a coating, and the preparation method is as follows:

[0106] 1) Take 21.05 g of an aqueous dispersion of nanocellulose with a mass fraction of 1.9 wt% (in this aqueous dispersion, the diameter of the nanocellulose is 2 - 20 nm and the length is 30 - 200 μm), pour it into deionized water and dilute it to 100 ml;

[0107] 2) Use an ultrasonic cell disruptor to ultrasonically disperse the nanocellulose until it is evenly dispersed;

[0108] 3) Add tris(hydroxymethyl)aminomethane to the nanocellulose dispersion to adjust the nanocellulose dispersion to weakly alkaline (pH around 8.5);

[0109] 4) Add 0.4 g of dopamine to the weakly alkaline nanocellulose dispersion, stir at room temperature for 24 h to form a mixed solution;

[0110] 5) Centrifuge and wash the mixed solution with deionized water several times to remove the unreacted dopamine, and obtain the final slurry;

[0111] 6) Pour part of the slurry into a spray gun, spray it on the substrate, and dry it to obtain a coating with a coating amount of about 16 g / m 2 of the coating.

[0112] The obtained coating surface is smooth and black, has a photothermal effect, but is hydrophilic on the surface.

[0113] Comparative Example 2

[0114] This comparative example provides a slurry and a coating, and the preparation method is as follows:

[0115] 1) Take 21.05 g of an aqueous dispersion of nanocellulose with a mass fraction of 1.9 wt% (in this aqueous dispersion, the diameter of the nanocellulose is 2 - 20 nm and the length is 30 - 200 μm), pour it into deionized water and dilute it to 100 ml;

[0116] 2) Use an ultrasonic cell disruptor to ultrasonically disperse the nanocellulose until it is evenly dispersed;

[0117] 3) Take 1.2 g of octadecylamine in ethanol, stir at 50 °C until dissolved, then pour it into the above-mentioned nanocellulose dispersion, and continue to stir for 24 h to form a mixed solution;

[0118] 4) Centrifuge and wash the mixed solution with ethanol several times to remove the unreacted octadecylamine, and obtain the final slurry;

[0119] 5) Pour part of the slurry into a spray gun, spray it on the glass substrate, and dry it at room temperature to obtain a coating with a coating amount of about 16 g / m2 coating

[0120] The obtained coating has a smooth surface and appears white, does not have a photothermal effect, and is hydrophilic on the surface.

[0121] Comparative Example 3

[0122] This comparative example provides a hydrophobic photothermal slurry and coating, and the preparation method is as follows:

[0123] 1) Take 0.4 g of dopamine and add it to 100 ml of deionized water;

[0124] 2) Take tris(hydroxymethyl)aminomethane and add it to the above solution to adjust the dopamine solution to be weakly alkaline (pH about 8.5);

[0125] 3) After stirring for 24 h, a polydopamine aqueous solution is formed;

[0126] 4) Take 1.2 g of octadecylamine in ethanol, stir at 50 °C until dissolved, then pour it into the polydopamine aqueous solution and continue to stir for 24 h to form a mixed solution;

[0127] 5) Centrifuge and wash the mixed solution with ethanol several times to remove unreacted dopamine and octadecylamine to obtain the final slurry;

[0128] 6) Pour part of the slurry into a spray gun and spray it on a glass substrate, and obtain black powder particles after drying at room temperature.

[0129] A coating cannot be formed, and the surface of the substrate is in a state of black powder accumulation, but water droplets can reach a superhydrophobic state on the powder.

[0130] Comparative Example 4

[0131] This comparative example provides a hydrophobic photothermal slurry and coating, and the preparation method is as follows:

[0132] 1) Take 21.05 g of an aqueous dispersion of nanocellulose (CNF) with a mass fraction of 1.9 wt%, pour it into deionized water and dilute it to 200 ml;

[0133] 2) Add 0.24 g of tris(hydroxymethyl)aminomethane to the nanocellulose dispersion to adjust the CNF dispersion to be weakly alkaline (pH about 8.5), and at the same time add 0.4 g of dopamine and 1.2 g of octadecylamine;

[0134] 3) Ultrasonically disperse the above mixed solution with an ultrasonic cell disruptor for 10 min;

[0135] 4) Then stir at 50 °C for 24 h;

[0136] 5) Centrifuge and wash the above mixed solution with deionized water several times to remove unreacted dopamine hydrochloride and octadecylamine to obtain the final slurry;

[0137] 7) Pour part of the slurry into the spray gun and spray it on the glass substrate. After drying at room temperature, the coating amount is about 16g / m 2 coating.

[0138] The resulting coating surface appears black and cannot achieve the state of light and heat anti-icing / de-icing.

[0139] Experimental Example 1-Hydrophobicity Test

[0140] In this experimental example, the hydrophobicity of the glass substrate coatings of various embodiments and comparative examples was tested.

[0141] The specific test method for hydrophobicity (contact angle) is as follows:

[0142] A 3 μL droplet was placed on the coating surface at an appropriate speed. After the droplet remained on the coating surface for 3 seconds, the contact angle was measured. The test results are shown in Table 1.

[0143] Table 1

[0144]

[0145] The static water contact angle image of the coating surface prepared in Example 1 is as follows Figure 1 shown.

[0146] The scanning electron microscope images of the coating surface at different magnifications are as follows Figure 2 As shown, from Figure 2 It can be seen that the coating surface is rough and porous, and nanoscale protrusions appear at high magnification. Therefore, it has a multi-level micron / nano structure, which is conducive to the construction of a superhydrophobic surface.

[0147] Summary: By varying the amount of added components, the surface microstructure and surface energy of nanocellulose-based superhydrophobic photothermal anti-icing / de-icing coatings can be manipulated, resulting in coatings with varying wettability. Examples 1, 7, 8, 11, and 12 achieve superhydrophobicity. In Comparative Example 1, since the hydrophobic agent ODA was not added, and since both CNF and PDA are hydrophilic, the resulting coating is also hydrophilic. In Comparative Example 2, since PDA was not added, although ODA was present, it was unable to graft with CNF. A small amount of ODA was present as a blend in the CNF / ODA coating, exhibiting hydrophilicity.

[0148] Experimental Example 2-Light Absorption Ability Test

[0149] The light absorption capacity of Example 1, Comparative Example 1, Comparative Example 2 and the glass substrate was tested in the full spectrum range (2500-200 nm) using a UV-visible-infrared spectrophotometer with an integrating sphere accessory.

[0150] Summary: As Figure 3 shown, for Example 1 and Comparative Example 1 with polydopamine added, their transmittance is almost 0 in the ultraviolet-visible light range, and the transmittance in the near-infrared region (760 nm - 1000 nm) is less than 40%, indicating that they have excellent absorption ability for light in this wavelength band, so their surfaces are black; for Comparative Example 2 without polydopamine added, its reflectance in the visible-near-infrared range is higher than 60%, and the transmittance is also higher than 30%, indicating that it does not have good absorption ability for light in this wavelength band, so its surface is white; for the glass substrate, its transmittance in the visible-infrared range is about 90%, so it is in a transparent state.

[0151] Experimental Example 3 - Photothermal Performance Test

[0152] The photothermal performance of Example 1, Comparative Example 1 and the glass substrate was tested.

[0153] The specific test method is as follows: Place the coated substrate or the glass substrate on a foam board (to reduce heat transfer), turn on the solar simulator to irradiate it, and while timing, use an infrared camera to take pictures of it, and record the change value of the surface temperature (°C) over time.

[0154] The test results are shown in Table 2.

[0155] Table 2

[0156]

[0157] Summary: As shown in Table 2 and Figure 4 shown, under the irradiation of simulated sunlight with a solar intensity of 1 sun (100 mW / cm 2 ²), for Comparative Example 1, due to the presence of polydopamine, its final equilibrium temperature can reach 64.8 °C; for Example 1, it can be heated from 20 °C to nearly 60 °C in 4 minutes, and its final equilibrium temperature can reach about 65.3 °C; for the glass substrate, even after 10 minutes of irradiation, its temperature change is small. This result shows that the nanocellulose-based superhydrophobic photothermal coating has excellent photothermal conversion ability, which is consistent with the results of Experimental Example 2.

[0158] Experimental Example 4 - Anti-icing Performance Test

[0159] The anti-icing performance of Example 1, Comparative Example 1 and the glass substrate was tested.

[0160] The specific test method is as follows: Place the coated substrate or the glass substrate on a hot and cold stage, use a pipette to take 20 μL of water droplets and place them on the solid surface. After the droplets are stable, let the cold stage cool down to the set temperature at a rate of 30 °C / min, and use a camera device to record until the droplets are completely frozen.

[0161] Summary: (1) AsFigure 5 (Left) As shown, when the set temperature is -15°C, for the hydrophilic glass substrate and Comparative Example 1, since the water droplets fully spread on it, they completely freeze in about 40 s. For the coating prepared in Example 1, since the superhydrophobic coating can capture the air layer, greatly reducing the contact area and heat transfer coefficient between the water droplets and the solid surface, after 7200 s, the water droplets still do not completely freeze, demonstrating excellent anti-icing performance at low temperatures for a long time. It should be noted that although the contact angle of the water droplets gradually decreases due to frosting on the surface of the superhydrophobic coating at low temperatures, it still has the effect of delaying ice formation.

[0162] (2) Figure 5 (Right) shows the ice formation time of water droplets on the surface of the coating prepared in Example 1 at different low temperatures. When the set temperature is -20°C, the water droplets completely freeze after 96 s. When the set temperature is further lowered to -25°C or even -30°C, the water droplets freeze immediately, indicating that the ice nucleation temperature on the surface of this coating is about -20°C.

[0163] Experimental Example 5 - Photothermal Anti-icing Performance Test

[0164] The photothermal anti-icing performance of Example 1 was tested.

[0165] The specific test method is the same as that in Experimental Example 4, but before the cold stage cools down, first irradiate the coating prepared in Example 1 with simulated sunlight at 100 mW / cm 2 for 10 minutes, and then keep irradiating and start to cool down.

[0166] Summary: As Figure 6 shown, even when the set temperature of the cold stage is -30°C, there is no sign of ice formation on the surface of the coating after 7200 s for the water droplets, demonstrating excellent anti-icing performance at low temperatures for a long time, indicating that the combination of superhydrophobic and photothermal properties has an excellent effect of delaying ice formation.

[0167] After adjusting the set temperature of the cold stage to -15°C, -20°C, and -25°C and conducting this experiment, the results are as Figure 7 shown, and it can be seen that there is no sign of ice formation on the surface of the coating after 7200 s for the water droplets.

[0168] Experimental Example 6 - Photothermal De-icing Performance Test

[0169] The photothermal de-icing performance of Example 1 and the glass substrate was tested.

[0170] The specific test method is as follows: Place the coatings prepared in Example 1 and Comparative Example 1 and the glass substrate in a -20°C refrigerator for pre-cooling. At the same time, place the pre-frozen cylindrical ice cubes on the surface of the samples and freeze them in the refrigerator for 12 h. After 12 h, the ice cubes will freeze on the surface of the samples. After placing the samples vertically, irradiate them with 100 mW / cm2 Irradiate with simulated sunlight and record the observations. The results are as Figure 8 shown.

[0171] Summary: As can be seen from Figure 8 , for the small icicles on the glass (with a volume of 2.12 cm 3 and a thickness of 0.4 cm), there is no change even after 600 s of irradiation; while for the small icicles on the surface of Example 1, they slide off within 100 s of irradiation; even when using larger icicles on the surface of Example 1 (with a volume of 18.09 cm 3 and a thickness of 1.0 cm), they continuously melt and slide off within 900 s, indicating that it has excellent photothermal de-icing ability.

[0172] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, based on the above description, other different forms of changes or modifications can be made. It is impossible to list all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A preparation method of a photothermal anti-icing / de-icing slurry, characterized in that, It includes the following steps: Under the condition of the presence of an alkaline catalyst, a water dispersion of nanocellulose is mixed and reacted with a polymer-based photothermal material monomer to obtain a first mixed solution; After mixing the first mixed solution with a hydrophobizing agent solution, grafting reaction and centrifugal washing are carried out to obtain the photothermal anti-icing / de-icing slurry.

2. The preparation method according to claim 1, characterized in that, The concentration of the water dispersion of nanocellulose is (0.3 - 0.5) g / 100 ml.

3. The preparation method according to claim 1, characterized in that, In the water dispersion of nanocellulose, the diameter of nanocellulose is 1 - 100 nm, preferably 2 - 20 nm; the length of nanocellulose is 10 - 300 μm, preferably 30 - 200 μm; or In the water dispersion of nanocellulose, the nanocellulose is lignocellulose, and the mass percentage of lignin in the lignocellulose is 1.99%, and the diameter is 4.6 ± 1.9 nm.

4. The preparation method according to claim 1, characterized in that The alkaline catalyst is selected from one of sodium hydroxide, potassium hydroxide, and tris(hydroxymethyl)aminomethane.

5. The preparation method according to claim 1, characterized in that, The polymer-based photothermal material monomer is selected from one of pyrrole, dopamine, thiophene, and aniline; and / or The mass ratio of the nanocellulose to the polymer-based photothermal material monomer is 1:(0.2 - 2), preferably 1:(0.6 - 1.5).

6. The preparation method according to claim 1, characterized in that, In the hydrophobizing agent solution, the hydrophobizing agent is selected from at least one of octadecylamine, octadecanethiol, polytetrafluoroethylene, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, polyhedral oligomeric silsesquioxane, polydimethylsiloxane, and octadecyltrimethoxysilane; and / or In the hydrophobizing agent solution, the solvent is selected from one or more of ethyl acetate, ethanol, N,N-dimethylformamide, and toluene; and / or The mass ratio of the nanocellulose to the hydrophobizing agent is 1:(0.5 - 5), preferably 1:(0.5 - 4.5); and / or The temperature of the grafting reaction is 25 - 70 °C, and the time is 12 - 36 h.

7. A photothermal anti-icing / de-icing slurry, characterized in that, It is prepared by the preparation method described in any one of claims 1 - 6.

8. A photothermal anti-icing / de-icing coating, characterized in that, It is obtained by coating the photothermal anti-icing / de-icing slurry prepared by the preparation method described in any one of claims 1 - 6 or the photothermal anti-icing / de-icing slurry described in claim 7 on a substrate and drying.

9. The photothermal anti-icing / de-icing coating according to claim 8, wherein The coating amount of the photothermal anti-icing / de-icing coating is 1-30 g / m 2 .

10. Application of the photothermal anti-icing / de-icing slurry prepared by the preparation method described in any one of claims 1 - 6 or the photothermal anti-icing / de-icing slurry described in claim 7 in the coating of paper products, fabrics, glass, or ceramic products.

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