Liquid crystal phase nanogel heating paint and preparation method thereof

Abstract

The application relates to the technical field of heat paint, and discloses liquid crystal phase nanogel heat paint and a preparation method thereof. The liquid crystal phase nanogel heat paint comprises a high-concentration nanomaterial dispersion liquid, and the high-concentration nanomaterial dispersion liquid is obtained by dispersing high-concentration nanomaterials and a dispersant. The high-concentration nanomaterials comprise nanomaterials and a solvent. The nanomaterials comprise component A. The component A is carbon nanotubes. The mass-volume ratio of the nanomaterials and the solvent is 2-20 mg / mL. The temperature during the dispersion is less than 15 DEG C. The energy density injected during the dispersion is greater than 20 J / mL. Through the technical scheme, the problem of low conductivity of the heat paint in the related art is solved. The heat paint prepared by the application can be prepared at normal temperature and normal pressure and coated on a substrate. The light transmittance and flexibility can be controlled according to practical requirements. Compared with traditional heat paint or electrothermal coating, the heat paint has a wider application scene and a simpler preparation process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat paint, in particular, relates to a liquid crystal phase nanogel heat paint and a preparation method thereof. BACKGROUND

[0002] At present, the paint used in the fields of furniture, automobile, building, interior decoration and the like is mainly paint and latex paint and the like, and these paints have low transparency, which limits their application scenarios, especially cannot be applied to scenarios such as glass, mirror, electronic equipment, protective screen of optical devices and the like which need to maintain the perspective characteristics of the substrate. Some special paints, such as polyurethane, epoxy resin and the like, although have light transmission. However, these materials as insulators cannot generate electrothermal effect through Joule heat, which means that they cannot be used for winter heating and protection of special instruments in cold conditions. On the other hand, there are some special paints on the market at present which can produce electrothermal effect by incorporating metal particles or metal wires, but due to the poor light transmission of metal, the coating constructed by these paints is often opaque, affecting the overall aesthetic appearance, and the coating constructed by these metal powder paints is often hard and brittle, lacking flexibility, limiting its performance on flexible substrates.

[0003] In the field of nanomaterials, carbon nanotubes and graphene are widely used in the preparation of transparent conductive films and flexible electrodes. Among them, some technical means adopt dispersing carbon nanomaterials in solvents to prepare conductive slurry or ink, and these conductive slurry is used to prepare transparent conductive coating (such as patent with application number CN202110345667.5 and patent with application number CN201910808072.1). However, due to the strong intermolecular force of carbon nanomaterials, it is difficult to fully disperse, especially in high-concentration dispersion liquid, a large amount of nanomaterials exist in the form of agglomerates, in which the nanowires or nanotubes are intertwined or form bundles, and it is difficult to realize oriented arrangement in the dispersion liquid or on the substrate, which is not conducive to electron transport. Although low-concentration dispersion can ensure dispersibility, it leads to low content of conductive nanomaterials in the coating, and the nanowires or nanotubes are arranged in a non-oriented network, which limits the conductivity of the coating. These factors limit the uniformity and conductivity of large-area coating, affecting the heating function.

[0004] Although some means can obtain the oriented arrangement of carbon nanotubes or other nanowires / fibers to enhance the electrical conductivity and mechanical properties of these nanotubes / nanowires, these methods are generally divided into dry and wet methods. Among them, the dry method generally directly synthesizes a nanotube / nanowire film in the growth synthesis stage by controlling the reaction conditions, and at the same time, the nanowires / nanotubes in the film are made to be oriented by controlling the flow rate of the reaction gas, the film collection speed and the pulling speed, etc. (such as CN104244689A, CN201410382307.2). Although the film constructed by this method has excellent electrical conductivity, it does not belong to the category of coatings, and its construction of conductive and electrothermal thin layer on the substrate depends on the intact and smooth transfer of the finished film to the substrate. For wet type means, generally use the dispersion liquid preparation method as described above to obtain the dispersion of nanotubes / nanowires in a specific solvent and dispersant, and then lay or deposit it on the substrate, or make fibers by spraying and pulling, etc. The nanotubes / nanowires in these dispersions can move freely and cannot form a liquid crystal phase without oriented domains, and generally need to be oriented into a thin film by shear force, capillary action, solvent evaporation speed, electromagnetic field guidance during the film forming process on the substrate (such as CN201610857060.4, CN201511032711.8, CN201811073606.2). Although these wet methods can obtain coatings and realize the oriented arrangement of nanotubes / nanowires on the substrate, they are characterized by fine adjustment of environmental conditions, solution composition, film forming process, or post-treatment of the film after film forming. It can be seen that the dispersion liquid relied on by this kind of way to construct an oriented film does not belong to a liquid crystal phase gel, and it is also difficult to construct an electrothermal coating on a building material or any surface on a large scale. Although the oriented thin film generally has excellent orientation and electrical conductivity, the realization of orientation depends on fine and complex film forming process. SUMMARY

[0005] The present application provides a liquid crystal phase nanogel heating coating and a preparation method thereof, which solves the problem of low electrical conductivity of the heating coating in the related art.

[0006] The technical scheme of the present application is as follows:

[0007] The present application provides a liquid crystal phase nanogel heating coating, which comprises a high-concentration nanomaterial dispersion liquid, wherein the high-concentration nanomaterial dispersion liquid is obtained by dispersing a high-concentration nanomaterial and a dispersant;

[0008] The high-concentration nanomaterial comprises a nanomaterial and a solvent;

[0009] The nanomaterial comprises a component A;

[0010] The component A is a carbon nanotube;

[0011] The mass-volume ratio of the nanomaterial and the solvent is 2-20 mg / mL;

[0012] The temperature during the dispersion is less than 15 DEG C.

[0013] The energy density injected during the dispersion is greater than 20 J / mL.

[0014] As a further technical solution, the high-concentration nanomaterial dispersion has a viscosity of 5-300 Pa s at 25 DEG C and a shear rate of 100 s -1 The viscosity at 25 DEG C is 0.1-10 Pa s, and the shear thinning coefficient is 0.02-1.

[0015] As a further technical solution, the mass ratio of the dispersant and the nanomaterial is 1:1-10:1; preferably, the mass ratio of the dispersant and the nanomaterial is 1:1-2:1.

[0016] In the present application, by adjusting the mass ratio of the dispersant and the high-concentration nanomaterial to 1:1-2:1, the conductivity and the heating performance of the heating paint are further improved.

[0017] As a further technical solution, the nanomaterial further comprises component B, the component B comprising a low-dimensional conductive nanomaterial other than carbon nanotubes and / or a hybrid of the low-dimensional conductive nanomaterial; preferably, the component B comprises one or more of metal nanowires, carbon nanotube-graphene hybrid, graphene, and carbon black.

[0018] As a further technical solution, the carbon nanotubes are one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, metallic carbon nanotubes, and semiconductive carbon nanotubes; the metal nanowires are one or both of silver nanowires and copper nanowires.

[0019] As a further technical solution, when the carbon nanotubes are single-walled carbon nanotubes, the mass-volume ratio of the single-walled carbon nanotubes and the solvent is 2-5 mg / mL; when the carbon nanotubes are multi-walled carbon nanotubes, the mass-volume ratio of the multi-walled carbon nanotubes and the solvent is 5-20 mg / mL.

[0020] As a further technical solution, the solvent is one or more of water, ethanol, methanol, isopropyl alcohol, toluene, N-methyl pyrrolidone, N,N-dimethylformamide, and cresol.

[0021] As a further technical solution, the dispersant is one or more of cholate surfactants, sulfonate surfactants, quaternary ammonium salt type cationic surfactants, and polymers mixed with the solvent; the polymers comprise one or more of perfluorosulfonic acid resin, polystyrene sulfonic acid, polyvinylpyrrolidone, and polyethylene glycol octylphenyl ether.

[0022] As a further technical solution, the cholate surfactant includes one or more of sodium dodecyl sulfate, sodium cholate, sodium deoxycholate, sodium hyodeoxycholate; the sulfonate surfactant includes one or more of sodium dodecyl benzene sulfonate, sodium dodecyl sulfonate.

[0023] The application further provides a preparation method of the liquid crystal phase nanogel heating paint, including the following steps: dispersing and mixing the high-concentration nanomaterial and a dispersant to obtain the liquid crystal phase nanogel heating paint.

[0024] As a further technical solution, the energy density injected during the dispersing is 50-200 J / mL; the dispersing includes ultrasonic dispersing or shearing dispersing; the effective sound energy density injected during the ultrasonic dispersing is 50-200 J / mL; the specific energy injected during the shearing dispersing is 50-200 J / mL.

[0025] In the application, by adjusting the parameters in the ultrasonic dispersing and shearing dispersing process, the conductivity and heating performance of the heating paint are further improved.

[0026] The application further provides a coating method of the liquid crystal phase nanogel heating paint, including the following steps: coating the liquid crystal phase nanogel heating paint on a substrate, and volatilizing the solvent to obtain a transparent nanometer conductive coating layer with a thickness of 50 nm-1 μm; the coating method is one of blade coating, spraying and spin coating.

[0027] As a further technical solution, when the liquid crystal phase nanogel heating paint does not include metal nanowires, 40 wt% of nitric acid can be sprayed or the coating layer can be treated with nitric acid vapor to improve the conductivity of the carbon nanotubes after the transparent electrothermal coating layer is obtained.

[0028] Compared with the traditional metal powder paint, the heating paint prepared in the application can be prepared and coated on a substrate at normal temperature and pressure, the light transmittance and flexibility can be controlled according to the practical requirements, and the heating paint has a wider application scenario and a simpler preparation process. The liquid crystal phase nanogel heating paint can build a uniform coating layer on a target substrate, and the coating layer can be as thin as nanometer level, and has good light transmittance. The nanomaterial in the built coating layer can still maintain good orientation, so that the carrier (electron and hole) transport speed in the axial direction is much higher than that in the radial direction, and the conductivity of the coating layer can be more than 10 4 S / cm. The high conductivity can generate a large number of joules in the powered state, and the electrothermal effect is excellent, so the liquid crystal phase nanogel heating paint can be applied to various fields as an electrothermal coating layer.

[0029] The working principle and beneficial effects of the application are as follows:

[0030] In the present application, the nanomaterials such as carbon nanotubes, metal nanowires, graphene, and graphene nanoribbons have excellent electrical conductivity and are ideal thermoelectric materials. The carrier (electron and hole) transport speed in these materials along the axial direction (or in the graphene plane) is much higher than that in the radial direction (or between the graphene layers). With the assistance of dispersant molecules, these nanomaterials are dispersed in the solvent from the agglomerate state to form a dispersion. Generally, these materials move freely in the dispersion without orientation. However, when the concentration of these nanomaterials is increased and sufficiently dispersed, the specific surface area of the nanomaterials increases, the total occupied space increases, and the depletion interaction between the nanomaterials is enhanced, which expels the dispersant molecules from the space between the nanomaterial molecules and causes the nanomaterial molecules to approach each other. The nanomaterial molecules tend to change from disordered arrangement to parallel arrangement to maintain the lowest free energy, thereby forming a liquid crystal phase. After the dispersion is coated on a substrate to form a film, the nanomaterial molecules can still maintain the liquid crystal phase arrangement, which allows the carrier to transport along the side-by-side arranged nanowires / nanotubes, reduces the influence of the junction resistance between the nanomaterial molecules, and enhances the electrical conductivity. Therefore, the key to realizing such a liquid crystal phase dispersion is to ensure that the nanomaterials are sufficiently dispersed at a high concentration and the free movement of the nanomaterial molecules in the dispersion is inhibited. In the present method, the type, concentration, and temperature of the nanomaterials in the dispersion stage are reasonably controlled to form a liquid crystal phase of the nanomaterials and crosslink the gel. The product obtained by the present method has high viscosity and gel-like appearance in macroscopic view, and has obvious domains and well-dispersed and oriented nanomaterials in microscopic view, which significantly improves the electrothermal performance of the heating coating. BRIEF DESCRIPTION OF DRAWINGS

[0031] The present application will be further described in detail below in conjunction with the drawings and specific embodiments.

[0032] Figure 1 The liquid crystal phase nanogel prepared in Example 1 of the present application,

[0033] In the figure: (a) is a graph of the viscosity of the nanogel versus the shear rate; (b) is a graph of the liquid crystal phase nanogel; (c) is a SEM graph of the liquid crystal phase nanogel;

[0034] Figure 2 The liquid crystal phase conductive film formed by the liquid crystal phase nanogel prepared in Example 10 of the present application,

[0035] Figure 3 The nanogel prepared in Comparative Example 1 of the present application,

[0036] In the figure: (a) is a graph of the viscosity of the nanogel versus the shear rate; (b) is a SEM graph of the nanogel;

[0037] Figure 4 The nanogel prepared in Comparative Example 2 of the present application,

[0038] In the figure: (a) is the nanogel viscosity changes with shear rate graph; (b) is the SEM of nanogel.

[0039] Figure 5 The nanogel prepared for the present application comparative example 3,

[0040] In the figure: (a) is the nanogel viscosity changes with shear rate graph; (b) is the SEM of nanogel. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0042] In the following examples and comparative examples, single-walled carbon nanotubes: average length 1 μm, tube diameter distribution 1.2~2.0 nm;

[0043] Multi-walled carbon nanotubes: average length 15 μm, tube diameter distribution 5~15 nm;

[0044] Silver nanowires: average length 20 μm, diameter distribution 25~35 nm;

[0045] Carbon nanotube-graphene hybrid: tube diameter distribution 1.2~2.0 nm, specific surface area 1200 m 2 / g;

[0046] Carbon black: particle size 30~45 nm;

[0047] Graphene: flake size 10~20 μm;

[0048] Copper nanowires: average length 20 μm, diameter distribution 40~50 nm.

[0049] In the following examples and comparative examples, the electrical heating performance of the coating will be characterized by the electrical conductivity or sheet resistance of the coating. Since the Joule heat where U is the applied voltage, is the electrical conductivity, t is the power-on time, A and L are the cross-sectional area and length of the coating. It can be seen that under the condition of constant applied voltage and coating thickness, the electrical conductivity of the coating determines the Joule heat generated per unit time and per unit area. Therefore, the electrical heating performance of the coating can be known by characterizing the electrical conductivity of the coating.

[0050] Example 1

[0051] The liquid crystal phase nanogel heating coating comprises a high-concentration nanomaterial dispersion liquid, and the high-concentration nanomaterial dispersion liquid comprises the following components: high-concentration nanomaterial, dispersant;

[0052] High concentration nanomaterial: 30 mg single-walled carbon nanotubes per 10 mL ethanol;

[0053] Dispersant: prepared by mixing perfluorosulfonic acid resin and ethanol, the mass fraction of perfluorosulfonic acid resin is 0.3wt%;

[0054] The high concentration nanomaterial is ultrasonically dispersed with the dispersant to obtain the liquid crystal phase nanogel heating coating; wherein the mass ratio of the dispersant and the nanomaterial is 1:1; wherein: the amplitude is 30% and the injected effective acoustic energy density is 80 J / mL during ultrasonic dispersion (ultrasonic instrument model SFX550, Branson).

[0055] During the dispersion process, the environmental temperature of the nanomaterial dispersion is controlled to be 10°C through a circulating cooling water system.

[0056] The liquid crystal phase nanogel obtained by ultrasonic dispersion has a viscosity far exceeding the dispersion liquid category and hardly flows downward in an inverted state, as shown in the viscosity change with shear rate graph of Figure 1 (a) and the liquid crystal phase nanogel graph of Figure 1 (b).

[0057] The liquid crystal phase nanogel heating coating is coated on a glass substrate by means of scraping, and after the solvent is volatilized, a nanometer conductive coating with a certain orientation and a thickness of 1 μm is formed, as shown in the SEM graph of the liquid crystal phase nanogel of Figure 1 (c). It can be seen that although a small amount of carbon nanotubes are distributed isotropically in the upper layer, most of the carbon nanotubes are arranged in a liquid crystal phase.

[0058] The surface of the coating is sprayed with 40wt% nitric acid to dope the carbon nanotubes and improve their conductivity.

[0059] After constructing an electrode at the edge of the coating, the heating effect is realized when electricity is passed through, and the conductivity of the nanometer conductive coating can reach 9000 S / cm.

[0060] Example 2

[0061] The liquid crystal phase nanogel heating coating comprises a high concentration nanomaterial dispersion liquid, and the high concentration nanomaterial dispersion liquid comprises the following components: high concentration nanomaterial, dispersant;

[0062] High concentration nanomaterial: 60 mg single-walled carbon nanotubes, 5 mg silver nanowires, and 5 mg carbon black per 10 mL water;

[0063] Dispersant: prepared by mixing sodium cholate and water, the mass fraction of sodium cholate is 1.4wt%;

[0064] The preparation method of the liquid crystal phase nanogel heating paint comprises the following steps:

[0065] The high-concentration nanomaterials are ultrasonically dispersed with the dispersant to obtain the liquid crystal phase nanogel heating paint; wherein the mass ratio of the dispersant to the nanomaterials is 2:1, and the effective sound energy density injected during ultrasonic dispersion is 80 J / mL.

[0066] During the ultrasonic dispersion process, the environmental temperature of the nanomaterial dispersion is controlled to be 10℃ through a circulating cooling water system.

[0067] The liquid crystal phase nanogel heating paint is coated on a glass substrate in a manner of blade coating, and after the solvent is volatilized, a nanometer conductive coating with a certain orientation and a thickness of 1 μm is formed.

[0068] The electric heating effect is realized after an electrode is constructed at the edge of the coating and is electrified, and the conductivity of the nanometer conductive coating reaches 12300 S / cm.

[0069] Example 3

[0070] The liquid crystal phase nanogel heating paint comprises a high-concentration nanomaterial dispersion liquid, and the high-concentration nanomaterial dispersion liquid comprises the following components: high-concentration nanomaterials and a dispersant.

[0071] The high-concentration nanomaterials: the nanomaterials in 10 mL of isopropyl alcohol include 10 mg of single-walled carbon nanotubes, 20 mg of multi-walled carbon nanotubes, 10 mg of copper nanowires, 9 mg of carbon nanotube-graphene hybrid, and 1 mg of graphene.

[0072] The dispersant is prepared by mixing perfluorosulfonic acid resin and isopropyl alcohol, and the mass fraction of the perfluorosulfonic acid resin is 1.0 wt%.

[0073] The preparation method of the liquid crystal phase nanogel heating paint comprises the following steps:

[0074] The high-concentration nanomaterials are ultrasonically dispersed with the dispersant to obtain the liquid crystal phase nanogel heating paint; wherein the mass ratio of the dispersant to the nanomaterials is 2:1, and the effective sound energy density injected during ultrasonic dispersion is 100 J / mL.

[0075] During the ultrasonic dispersion process, the environmental temperature of the nanomaterial dispersion is controlled to be 10℃ through a circulating cooling water system.

[0076] The liquid crystal phase nanogel heating paint is coated on a glass substrate in a manner of blade coating, and after the solvent is volatilized, a nanometer conductive coating with a certain orientation and a thickness of 1 μm is formed.

[0077] The electric heating effect is realized after an electrode is constructed at the edge of the coating and is electrified, and the conductivity of the nanometer conductive coating reaches 11200 S / cm.

[0078] Example 4

[0079] The liquid crystal phase nanogel heating paint comprises a high-concentration nanomaterial dispersion liquid, and the high-concentration nanomaterial dispersion liquid comprises the following components: a high-concentration nanomaterial and a dispersant.

[0080] The high-concentration nanomaterial comprises 150 mg of multi-walled carbon nanotubes and 20 mg of carbon nanotube-graphene hybrid in 10 mL of water.

[0081] The dispersant is prepared by mixing sodium hyodeoxycholate and sodium deoxycholate in a mass ratio of 1:1 and water, and the total mass fraction of the sodium hyodeoxycholate and the sodium deoxycholate is 1.7 wt%.

[0082] The preparation method of the liquid crystal phase nanogel heating paint comprises the following steps:

[0083] The high-concentration nanomaterial is sheared and dispersed with the dispersant to obtain the liquid crystal phase nanogel heating paint; wherein the mass ratio of the dispersant to the nanomaterial is 1:1, and the specific energy injected in the shearing and dispersing process is 80 J / mL.

[0084] In the shearing and dispersing process, the environmental temperature of the nanomaterial dispersion is controlled to be 10°C through a circulating cooling water system.

[0085] The liquid crystal phase nanogel heating paint is coated on a glass substrate by means of blade coating, and after the solvent is volatilized, a nanometer conductive coating with a certain orientation and a thickness of 1 μm is formed.

[0086] The surface of the coating is sprayed with 40 wt% nitric acid to dope the carbon nanotubes and improve the conductivity thereof.

[0087] The electrode is constructed at the edge of the coating, and the electrothermal effect is realized after being electrified, and the electrical conductivity reaches 6300 S / cm.

[0088] Example 5

[0089] The difference between this embodiment and Example 2 is only that the mass ratio of the dispersant to the high-concentration nanomaterial is 10:1.

[0090] Example 6

[0091] The difference between this embodiment and Example 2 is only that the mass ratio of the dispersant to the high-concentration nanomaterial is 1:1.

[0092] Example 7

[0093] The difference between this embodiment and Example 6 is only that the effective sound energy density injected in the ultrasonic dispersion is 250 J / mL.

[0094] Example 8

[0095] The difference between this example and Example 6 is that the effective acoustic energy density injected during ultrasonic dispersion is 50 J / mL.

[0096] Example 9

[0097] The difference between this example and Example 6 is that the effective acoustic energy density injected during ultrasonic dispersion is 200 J / mL.

[0098] Example 10

[0099] The difference between this example and Example 2 is that the electrothermal coating is constructed by spraying, and the thickness of the coating is about 50 nm, which exhibits good light transmittance, with a light transmittance of 85% at 550 nm, a film square resistance of 60 ohm / sq, and a liquid crystal phase transparent conductive film as shown in Figure 2 The conductivity can be calculated using the formula , where is the transmittance of light of a wavelength, is the square resistance of the film, is the conductivity of the film, and the photoconductivity of the carbon nanotubes is 200 S / cm. By substituting the square resistance and the light transmittance, the conductivity of the film is 7800 S / cm.

[0100] Example 11

[0101] The difference between this example and Example 2 is that the mass ratio of the dispersant to the nanomaterial is 1:2.5.

[0102] Example 12

[0103] The difference between this example and Example 2 is that the mass ratio of the dispersant to the nanomaterial is 11:1.

[0104] Comparative Example 1

[0105] The difference between this comparative example and Example 1 is that the concentration of the single-walled carbon nanotubes is 1 mg / mL, i.e., 10 mg of nanomaterial (single-walled carbon nanotubes) per 10 mL of water. After dispersion, the viscosity is low, and the carbon nanotubes are in a solution state without being crosslinked into a gel in the dispersion, as shown in the viscosity vs. shear rate graph of Figure 3 (a) and the SEM image of the nanogel of Figure 3 (b).

[0106] Comparative Example 2

[0107] The difference between this comparative example and Example 1 is that the effective acoustic energy density injected is 20 J / mL, and the carbon nanotube dispersion obtained by ultrasonic dispersion has a high viscosity. The carbon nanotube dispersion is coated on a substrate by doctor blading to form an electroconductive coating, as shown in the viscosity vs. shear rate graph of Figure 4 (a) and the SEM image of the nanogel of Figure 4SEM images of the nanogel of (b) are shown.

[0108] Comparative Example 3

[0109] The difference between the present comparative example and Example 1 is that the temperature of the dispersion system is not controlled during the dispersion process, and the temperature gradually reaches 80°C during the dispersion process. Finally, the carbon nanotube dispersion liquid has a higher viscosity and poorer dispersibility, as shown in Figure 5 The viscosity change graph of (a) with shear rate and Figure 5 The SEM images of the nanogel of (b) are shown.

[0110] The edge of the nanometer conductive coating prepared by Examples 1-12 and Comparative Examples 1-3, respectively, was constructed into an electrode to detect its conductivity, and the results are shown in the following table.

[0111]

[0112] Examples 1-4 show that the technical scheme for preparing a liquid crystal phase nanogel is suitable for a variety of different dispersion systems, including different dispersants, different nanomaterials, and different solvents corresponding to the dispersants.

[0113] Example 10 shows that the coating obtained by the present technical scheme can be used to prepare an electrothermal coating with different light transmittances.

[0114] Comparing Examples 2, 5, 6 and Examples 11, 12, the coating prepared by Examples 2, 5, and 6 has a higher conductivity, which shows that the ratio of dispersant and nanomaterial has a key influence on the electrical properties of the coating. When the ratio of dispersant is too high in Example 12, these non-conductive dispersant molecules will increase the resistance of the coating; when the ratio of dispersant is too low in Example 11, it cannot effectively disperse high-concentration nanomaterials, and the agglomerated nanomaterials have poor conductivity, resulting in an increase in the resistance of the coating.

[0115] Comparing Example 1 with Comparative Example 1, the coating prepared by Example 1 has a higher conductivity, which shows that the concentration of nanomaterials is a key factor for forming a liquid crystal phase gel. In Comparative Example 1, the concentration is below the defined range, and the carbon nanotubes cannot be crosslinked with each other in the dispersion, so the dispersion remains in a solution state, and the nanotubes move freely in the solution and cannot form a nematic phase arrangement. Therefore, although the nanotubes are well dispersed in the nanometer coating constructed in Comparative Example 1, the random arrangement of nanotubes and the X-type junctions in the network film are not conducive to carrier transport, and the conductivity is not as good as that of Example 1.

[0116] Compared with Comparative Example 2, the coating prepared in Example 1 has higher conductivity, which indicates that the dispersion condition is very important for the formation of the liquid crystal phase nanogel. In Comparative Example 2, the effective acoustic energy density for dispersion is low, which leads to that most of the carbon nanotubes are not effectively dispersed, and these carbon nanotubes exist in the form of bundles and cannot spontaneously form a liquid crystal phase. In the coating layer prepared by using the dispersion as the coating, there is no domain of oriented arrangement of the carbon nanotubes, and the conductivity of the agglomerated nanomaterials is also poor, which leads to that the conductivity of the coating layer is much lower than that of Example 1.

[0117] Compared with Comparative Example 3, the coating prepared in Example 1 has higher conductivity, which indicates that the environmental temperature during the dispersion process is crucial for the formation of the liquid crystal phase gel. During the ultrasonic dispersion process, the temperature continuously increases due to the inevitable conversion of part of the external energy input into heat energy dissipation through friction. On the one hand, the rapid evaporation of the solvent leads to the continuous change of the concentration; on the other hand, the increase of the temperature leads to the decrease of the dispersion efficiency. The agglomeration of the carbon nanotubes at high temperature is also not conducive to the improvement of the dispersibility. For example, the dispersion of the carbon nanotubes in the solvent is shown in FIG. 2. Figure 5 (b) It can be seen that the dispersibility of the carbon nanotubes in the coating is poor, most of the carbon nanotubes exist in the form of agglomerates and bundles, and there is no single carbon nanotube, and the conductivity of the coating layer constructed thereby is low.

[0118] The above only describes the preferred embodiments of the present application and should not be used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A liquid crystal phase nanogel heating coating, characterized in that, The invention includes a high-concentration nanomaterial dispersion, which is obtained by dispersing high-concentration nanomaterials and a dispersant. The high-concentration nanomaterials include nanomaterials and solvents; The nanomaterial includes component A; Component A is carbon nanotubes; The mass-to-volume ratio of the nanomaterial to the solvent is 2~20 mg / mL; The temperature during dispersion is less than 15°C; The energy density injected during dispersion is greater than 20 J / mL; The mass ratio of the dispersant to the nanomaterial is 1:1 to 10:

1.

2. The liquid crystal phase nanogel heating coating according to claim 1, characterized in that, The high-concentration nanomaterial dispersion has a viscosity of 5~300 Pa·s at 25℃ and a shear rate of 100s⁻¹. -1 The viscosity is 0.1~10 Pa·s, and the shear thinning coefficient is 0.02~1.

3. The method for preparing a liquid crystal phase nanogel heating coating according to claim 1, characterized in that, The mass ratio of the dispersant to the nanomaterial is 1:1 to 2:

1.

4. The liquid crystal phase nanogel heating coating according to claim 3, characterized in that, The nanomaterials also include component B, which comprises low-dimensional conductive nanomaterials other than carbon nanotubes and / or hybrids of the low-dimensional conductive nanomaterials.

5. The liquid crystal phase nanogel heating coating according to claim 4, characterized in that, Component B includes one or more of the following: metal nanowires, carbon nanotube-graphene hybrids, graphene, and carbon black.

6. The liquid crystal phase nanogel heating coating according to claim 5, characterized in that, The carbon nanotubes are one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, metallic carbon nanotubes, and semiconducting carbon nanotubes; the metallic nanowires are one or two of silver nanowires and copper nanowires.

7. The liquid crystal phase nanogel heating coating according to claim 1, characterized in that, When the carbon nanotubes are single-walled carbon nanotubes, the mass-to-volume ratio of single-walled carbon nanotubes to solvent is 2~5 mg / mL; when the carbon nanotubes are multi-walled carbon nanotubes, the mass-to-volume ratio of multi-walled carbon nanotubes to solvent is 5~20 mg / mL.

8. The liquid crystal phase nanogel heating coating according to claim 1, characterized in that, The solvent is one or more of water, ethanol, methanol, isopropanol, toluene, N-methylpyrrolidone, N,N-dimethylformamide, and cresol.

9. The liquid crystal phase nanogel heating coating according to claim 1, characterized in that, The dispersant is obtained by mixing one or more of the following: bile salt surfactants, sulfonate surfactants, quaternary ammonium salt cationic surfactants, and polymers with a solvent; the polymer includes one or more of perfluorosulfonic acid resins, polystyrene sulfonic acid, polyvinylpyrrolidone, and polyethylene glycol octylphenyl ether.

10. A method for preparing a liquid crystal phase nanogel heating coating according to any one of claims 1 to 9, characterized in that, Includes the following steps: The high-concentration nanomaterials and dispersant are dispersed and mixed to obtain a liquid crystal phase nanogel heating coating.

11. The method for preparing a liquid crystal phase nanogel heating coating according to claim 10, characterized in that, The energy density injected during dispersion is 50~200J / mL.

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