Hydrogel material, method for preparing hydrogel material, and ice-repellent coating

Abstract

The present application relates to the technical field of anti-icing, and provides a water gel material for promoting ice nucleation, a preparation method of the water gel material and an anti-icing coating, which can solve at least part of the problems existing in the ice nucleation materials in the prior art. The water gel material has a polymer network structure, which is obtained by mixing and reacting a first monomer, a second monomer, a photoinitiator and a crosslinking agent in water and then solidifying. The first monomer is a compound having an enamide group, and the second monomer has an enoic acid group. Experiments prove that the water gel material provided by the present application can induce the rapid formation and growth of ice nuclei at an ambient temperature of-2 DEG C. Compared with the existing ice nucleation materials, the water gel material has a higher nucleation temperature and good optical effect, and does not affect the transparency of the material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of anti-icing, more particularly to a water gel material for promoting ice nucleation, a preparation method of the water gel material and an anti-icing coating. BACKGROUND

[0002] Ice and snow are common in our daily life, and the most common phenomenon in nature is that liquid water freezes into solid ice. In terms of ice crystal formation, nature also has its unique and ingenious method to control ice crystal formation, for example, there is a special family of proteins in the protein world. Two important branches of ice-binding proteins and nucleation proteins can affect ice crystal formation in completely opposite ways. The molecular weight of anti-icing protein is generally 3000-35000 Da, and it usually appears as a monomer protein molecule. It can be adsorbed on the surface of ice crystals, making the ice crystals curved, and according to the Kelvin effect, inhibiting the further growth of ice crystals. Anti-icing protein is one of the most efficient biological anti-icing agents at present, but the extraction of anti-icing protein from biological bodies is a very tedious and inefficient process. Although anti-icing protein can be artificially synthesized by gene expression method, its price is also very expensive. And most of the anti-icing proteins have poor stability and are easily inactivated, so they have not been widely used.

[0003] Nucleation protein, on the other hand, is much larger than anti-icing protein, with a molecular weight generally greater than 100000 Da, and often appears in the form of a multimer. Nucleation protein can promote ice nucleation, allowing ice to form at higher subzero temperatures.

[0004] In cold environments, ice and frost can cause serious problems to transportation vehicles (such as airplanes, cars), energy facilities (such as wind turbine blades, power transmission lines) and public infrastructure (such as bridges, roads), affecting their normal operation and safety. Traditional deicing methods, such as chemical deicing agents and mechanical deicing, can have adverse effects on the environment, so it is urgent to develop more environmentally friendly solutions. With the development of new materials and surface technology, it is possible to find materials that can effectively inhibit or control the ice nucleation process. The discovery and application of high-efficiency ice nucleation agents is a direct manifestation of this progress. By engineering the surface of materials, it is possible to precisely control their influence on ice nucleation and growth, thereby effectively inhibiting the adhesion and accumulation of ice.

[0005] However, the addition of some traditional ice nucleation materials can affect other properties of the coating, such as reducing transparency, which may not be desirable in some applications. Non-uniform application of traditional coatings can result in inconsistent anti-icing performance in different areas of the surface, affecting the overall effect. SUMMARY

[0006] In view of the above problems of the prior art, the technical scheme of the present application provides a hydrogel material for promoting ice nucleation, a preparation method of the hydrogel material and an ice prevention coating, which can solve at least part of the problems existing in the ice nucleation materials in the prior art.

[0007] In one aspect of the present application, a hydrogel material is provided, which has a polymer network structure obtained by curing a mixture of a first monomer, a second monomer, a photoinitiator and a crosslinking agent after reaction in water, the first monomer being a compound having an enamide group, and the second monomer having an enoic acid group.

[0008] According to the technical scheme of the present application, the hydrogel material obtained by polymerization of the first monomer and the second monomer through photoinitiation has a polymer network structure with mutual connection and close arrangement, which can ensure the hydrophilicity of the material while obtaining a large specific surface area, and the good water solubility enables the hydrogel material to have excellent hydrophilic performance. Since ice is formed by the ordered arrangement of water molecules in a low-temperature environment, the polymerized network structure can provide an effective platform and template for the arrangement of water molecules. In addition, the excellent hydrophilicity and large specific surface area of the gel enable it to adsorb more water molecules, which provides a convenient basic condition for the formation of ice. The specific size combined with the unique physicochemical properties possessed by the surface of the gel particles enables the gel particles to play a great promoting role in the ice nucleation process, thereby effectively improving the temperature at which pure water freezes into ice.

[0009] Experiments have proved that the hydrogel material provided by the present application can induce the rapid formation and growth of ice nuclei at an environmental temperature of-2℃, and compared with the existing ice nucleation materials, it has a higher nucleation temperature and good optical effect without affecting the transparency of the material.

[0010] As a preferred technical scheme of the present application, the hydrogel material is in the form of particles, and the particle size of the hydrogel material is 10-100 microns.

[0011] According to the preferred technical scheme, the small-particle-size hydrogel material can have better optical properties and be better compatible with other materials, so that the smoothness and transparency of the material can be better maintained.

[0012] As a preferred technical scheme of the present application, the first monomer is methacrylamide, and the second monomer is methacrylic acid.

[0013] According to the preferred technical scheme, methacrylamide and methacrylic acid can generate a more compact polymer network structure under the action of photoinitiated polymerization, thereby increasing the specific surface area of the hydrogel material and further promoting ice nucleation.

[0014] As a preferred technical solution of the present application, the crosslinking agent is selected from one or more combinations of dimethyl acrylamide, N,N'-methylene bisacrylamide and glutaraldehyde, and the initiator is selected from at least one of ammonium persulfate, potassium persulfate and sodium persulfate.

[0015] As a preferred technical solution of the present application, the mass fractions of the first monomer, the second monomer, the crosslinking agent and the photoinitiator in the hydrogel material are:

[0016] The first monomer is 200-800 parts by mass;

[0017] The second monomer is 200-800 parts by mass;

[0018] The crosslinking agent is 30-50 parts by mass;

[0019] The photoinitiator is 50-120 parts by mass.

[0020] According to the preferred technical solution, by controlling the ratio of the first monomer and the second monomer, the first monomer and the second monomer in the hydrogel material can form a hydrogel material with a size-controllable, uniformly polymer network structure with mutual connection and close arrangement under the action of the initiator and the promotion of the crosslinking agent, so that the hydrogel material has excellent performance in promoting ice nucleation.

[0021] The second aspect of the present application provides a preparation method of a hydrogel material, comprising the following steps:

[0022] The mixing step, the first monomer with a dilene amide group and the second monomer with an enoic acid group are weighed separately and then dissolved in water, and appropriate amounts of crosslinking agent and photoinitiator are added in sequence to obtain a first solution;

[0023] The curing step, an appropriate amount of the first solution is added dropwise into a mold and placed in a UV lamp box for curing to obtain a hydrogel material.

[0024] According to the preferred technical solution, the first monomer and the second monomer in the hydrogel material can form a hydrogel with a size-controllable, uniformly polymer network structure with mutual connection and close arrangement under the action of the initiator and the promotion of the crosslinking agent, so that the material has excellent performance in promoting ice nucleation, and also does not affect the transparency of other materials.

[0025] As a preferred technical solution of the present application, the preparation method of the hydrogel material further comprises:

[0026] The polishing step, the hydrogel material is dried in a freeze dryer and then put into a ball mill to polish to form hydrogel particles with a particle size of 10-100 μm.

[0027] According to the preferred technical solution, the pre-treatment of the freeze dryer is beneficial to the quick freeze-drying of the hydrogel material and facilitates the grinding of the ball mill.

[0028] According to the preferred technical solution, the mixing step further comprises:

[0029] The PH of the first solution is adjusted to be less than 7.

[0030] According to the preferred technical solution, the first monomer and the second monomer are more likely to emit light to initiate the polymerization reaction in an acidic environment, and the polymer network structure is formed quickly and uniformly.

[0031] According to the preferred technical solution, the solidification step is followed by:

[0032] The cleaning step comprises immersing the hydrogel material in water and then immersing the hydrogel material in cyclohexane.

[0033] According to the preferred technical solution, on the one hand, the repeated washing of water can clean the unreacted first monomer or second monomer as much as possible; on the other hand, cyclohexane can replace the water in the hydrogel, which affects the anti-icing effect of the overall material.

[0034] The third aspect of the present application provides an anti-icing coating, which comprises the hydrogel material provided in any of the technical solutions described above. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a flowchart of the method for preparing the hydrogel material provided in the embodiments of the present application. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] The embodiments of the present application provide a hydrogel material, which has a polymer network structure. The polymer network structure is formed by the interpenetration and crosslinking of a first monomer and a second monomer. Specifically, the first monomer having an enamide group, the second monomer having an enoic acid group, a photoinitiator and a crosslinking agent are mixed in water, and then irradiated and solidified (for example, ultraviolet lamp irradiation and solidification) to obtain the hydrogel material having the polymer network structure.

[0038] The polymer network structure formed by the interpenetrating crosslinking of the first monomer and the second monomer is closely arranged, such structure can ensure the hydrophilicity of the material while obtaining a larger specific surface area, and the good water solubility makes the hydrogel material have excellent hydrophilic performance.

[0039] Since ice is formed by the ordered arrangement of water molecules in a low-temperature environment, the polymer network structure can provide an effective platform and template for the arrangement of water molecules, which is conducive to guiding the controllable and uniform nucleation of water molecules. In addition, the excellent hydrophilicity and larger specific surface area of the gel enable it to adsorb more water molecules, which provides a convenient basis condition for ice formation. The specific size combined with the unique physicochemical properties possessed by the surface of the gel particles enables the gel particles to play a great promoting role in the ice nucleation process, thereby effectively improving the temperature at which pure water freezes into ice. Compared with existing ice nucleation materials, it has a higher nucleation temperature and good optical effect, and does not affect the transparency of the material.

[0040] In the present application, the specific selection of the first monomer and the second monomer is not limited, and those skilled in the art can freely select an organic compound having an enamide group as the first monomer, and select an organic compound having an enoic acid group as the second monomer. Based on the types of the first monomer and the second monomer, the photoinitiator and the crosslinking agent are selected accordingly to form a hydrogel material with a polymer network, which does not exceed the protection scope of the present application.

[0041] Preferably, the first monomer can be selected from methacrylamide; the second monomer can be selected from methacrylic acid. The molecules of methacrylamide and methacrylic acid are small, and the steric hindrance is also small, which can generate a more compact polymer network structure under the action of photopolymerization, improve the specific surface area of the hydrogel material, and further promote ice nucleation.

[0042] Further preferably, based on the specific selection of the first monomer and the second monomer, the crosslinking agent can be selected from one or more combinations of dimethylacrylamide, N,N'-methylenebisacrylamide and glutaraldehyde, and the initiator can be selected from at least one of ammonium persulfate, potassium persulfate and sodium persulfate.

[0043] Preferably, the mass fraction of the first monomer, the second monomer, the crosslinking agent and the photoinitiator in the hydrogel material can be: 200-800 parts by mass of the first monomer; 200-800 parts by mass of the second monomer; 30-50 parts by mass of the crosslinking agent; and 50-120 parts by mass of the photoinitiator. Further, the mass ratio of the first monomer and the second monomer in the hydrogel is 1-9:1-9, for example, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1 or 8:1, and the like. By controlling the ratio of the first monomer and the second monomer, the first monomer and the second monomer in the hydrogel material can form a hydrogel material with a size-controllable, uniformly polymerized network structure under the action of the initiator and the promotion of the crosslinking agent, so that the hydrogel material has excellent performance in promoting ice nucleation.

[0044] In addition, in order to meet the needs of different coating preparations and improve the optical performance of the hydrogel material in the coating, the hydrogel material is preferably controllably polished to form hydrogel particles of different particle sizes, so as to better maintain the smoothness and transparency of the material. Preferably, the particle size of the hydrogel material is 10-100 μm. The hydrogel material with small particle size can have better optical properties, better compatibility with other materials, and better maintain the smoothness and transparency of the material. Since the hydrogel material has a certain toughness, the brittleness of the hydrogel material can be further improved by freezing and the like, so as to facilitate breaking and grinding, and to maintain the particle size of the polished hydrogel particles more uniform.

[0045] The following experiments further demonstrate the anti-icing performance of the transparent thermal insulation coating provided by the embodiment.

[0046] 1. Material preparation

[0047] Figure 1 is a flowchart of the preparation method of the hydrogel material provided by the embodiment of the present application. As shown in Figure 1 , the preparation method of the hydrogel material includes the following steps:

[0048] In the mixing step S1, the first monomer with a dilenamide group and the second monomer with an enoic acid group are weighed and then dissolved in water, and then an appropriate amount of crosslinking agent and photoinitiator is added in sequence to obtain a first solution.

[0049] Preferably, in the mixing step, the pH of the first solution is adjusted to be less than 7. Specifically, the pH adjuster is selected from at least one of hydrochloric acid, sulfuric acid and phytic acid, which is not limited herein. In an acidic environment, the first monomer and the second monomer can emit a photoinitiated polymerization reaction more easily, quickly and uniformly to form a polymer network structure.

[0050] The curing step S2 is to take an appropriate amount of the first solution and drop it into the mold, and place it in the ultraviolet lamp box for curing to obtain the hydrogel material.

[0051] Preferably, the method for preparing the hydrogel material further comprises:

[0052] The polishing step S3 is to dry the hydrogel material in the freeze dryer and then put it into the ball mill to polish the hydrogel particles with a particle size of 10-100 μm. The pre-treatment of the freeze dryer is conducive to the rapid freeze-drying of the cured hydrogel material, and also facilitates the polishing of the ball mill.

[0053] Further preferably, after the curing step S2, it further comprises:

[0054] The cleaning step S4 is to first soak the hydrogel material in water, and then soak the hydrogel material in cyclohexane. On the one hand, repeated washing with water can wash as much as possible the unreacted first monomer or second monomer; on the other hand, cyclohexane can replace the water in the hydrogel to avoid the case that the residual water in the hydrogel material freezes and affects the anti-icing effect of the overall material.

[0055] In the first solution, the mass ratio of the first monomer and the second monomer to water is 5-25 wt%. By mixing the first monomer and the second monomer in this mass ratio range in water, the first monomer and the second monomer can be more fully reacted, and the yield of the hydrogel can be improved.

[0056] Specifically, in the present embodiment, first, the mixing step S1 is performed, 2 ml of methacrylic acid (second monomer) is slowly dissolved in 10 ml of ultrapure water, after a uniform temperature solution is formed, 2 g of methacrylamide (first monomer) is weighed and added to the solution and ultrasonic for 30 minutes, and the first monomer and the second monomer are fully dissolved after being shaken, 200 mg of crosslinking agent methylene bisacrylamide (BISNN;) is then added and ultrasonic for 10 minutes, and after complete dissolution, it is used as solution A. 200 mg of photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (UV-2959) is completely dissolved in 10 ml of ultrapure water as solution B. Solution B is slowly added to solution A, and constant stirring is required during the whole process. After the solution is stable, the first solution is obtained. If the PH of the first solution is greater than 7, hydrochloric acid solution is added until the PH of the first solution is less than 7.

[0057] Then, the curing step S2 is performed, the polytetrafluoroethylene mold is placed in the ultraviolet lamp box, 5 ml of the first solution is dropped into the mold, the power of the ultraviolet lamp box is adjusted to 100 w, the light exposure time is set to 30 minutes, and after the light exposure is completed, the hydrogel material is taken out when it is cooled to room temperature.

[0058] Then, a cleaning step S4 is performed, the hydrogel material obtained in the solidifying step S2 is repeatedly washed with pure water, and then is soaked in pure water for one week to remove unreacted monomers and other impurities. After the hydrogel is completely cleaned, cyclohexane is used to replace the water in the gel.

[0059] Finally, a polishing step S3 is performed, the cleaned hydrogel material is pre-frozen using liquid nitrogen, and then is dried at 80°C for 24h by a freeze dryer to obtain a dried gel material. After the obtained material is pre-crushed, it is added to the chamber of a ball mill, and different ball milling speeds are set according to different requirements to obtain corresponding gel particle materials.

[0060] In the present embodiment, the first monomer and the second monomer in the hydrogel material can form a hydrogel with a controllable size and a polymer network structure with mutual connection and close arrangement under the action of an initiator and the promotion of a crosslinking agent, so that the material has excellent performance in promoting ice nucleation and does not affect the transparency of other materials.

[0061] 2. Material characterization

[0062] In-situ ice nucleation test of hydrogel material

[0063] A gel particle powder with a mass fraction of 10% is weighed and dispersed in ultrapure water. A microsyringe is used to suck 0.2μl of the solution onto a silicon wafer to form a small droplet. The above operation is repeated until 20 small droplets are formed. The silicon wafer is placed in a cold table, and the freezing temperature of the droplets is observed and recorded in-situ by controlling the cooling rate. The nucleation temperature of the above-mentioned ice nucleation agent is-3℃. Experiments show that the hydrogel material provided in the present embodiment can induce rapid formation and growth of ice nuclei at an ambient temperature of-2℃, and has a higher nucleation temperature compared with existing ice nucleation materials.

[0064] In some other embodiments of the present application, an anti-icing coating is also provided, which comprises the hydrogel material provided in any of the above embodiments.

[0065] So far, the technical solutions of the present application have been described in conjunction with the drawings, but it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to related technical features without departing from the principles of the present application, and the technical solutions after the changes or replacements will fall within the protection scope of the present application.

Claims

1. An icephobic coating, characterized in that, The hydrogel material comprises a polymer network structure obtained by mixing a first monomer, a second monomer, a photoinitiator and a crosslinking agent in water and then curing under light, The first monomer has an olefin amide group, and the second monomer has an olefin acid group; The hydrogel material is dried in a freeze dryer and then ground in a ball mill to form hydrogel particles with a particle size of 10-100 μm; The mass fraction of the first monomer, the second monomer, the crosslinking agent and the photoinitiator in the hydrogel material is: The first monomer is 200-800 parts by mass; The second monomer is 200-800 parts by mass; The crosslinking agent is 30-50 parts by mass; The photoinitiator is 50-120 parts by mass.

2. The anti-ice coating of claim 1, wherein, The first monomer is methacrylamide, and the second monomer is methacrylic acid.

3. The anti-ice coating of claim 2, wherein, The crosslinking agent is N,N'-methylene bisacrylamide and / or glutaraldehyde, and the initiator is selected from at least one of ammonium persulfate, potassium persulfate and sodium persulfate.

4. The anti-ice coating of claim 1, wherein, The preparation method of the hydrogel material comprises: A mixing step, in which a first monomer having a dilute olefin amide group and a second monomer having an olefin acid group are weighed and then dissolved in water, and an appropriate amount of crosslinking agent and photoinitiator are added in sequence to obtain a first solution; A curing step, in which an appropriate amount of the first solution is added dropwise to a mold and cured in a UV lamp box to obtain the hydrogel material.

5. The anti-ice coating of claim 4, wherein, The preparation method of the hydrogel material further comprises: A grinding step, in which the hydrogel material is dried in a freeze dryer and then ground in a ball mill to form hydrogel particles with a particle size of 10-100 μm.

6. The anti-ice coating of claim 4, wherein, In the mixing step, it also includes: Adjusting the PH of the first solution to be less than 7.

7. The anti-ice coating of claim 4, wherein, After the curing step, it also includes: A cleaning step, in which the hydrogel material is first soaked in water and then soaked in cyclohexane.

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