CN114381160B

CN114381160B - Modified graphene oxide, preparation method thereof and coating

Info

Publication number: CN114381160B
Application number: CN202210086203.1A
Authority: CN
Inventors: 陈强; 赵悦菊; 郭淼; 王建辉; 郑永立; 石金彪; 赵春风; 谢熙威; 郭渊; 李星伟
Original assignee: Beijing Guodian Futong Science and Technology Development Co Ltd
Current assignee: Beijing Guodian Futong Science and Technology Development Co Ltd
Priority date: 2022-01-25
Filing date: 2022-01-25
Publication date: 2023-02-10
Anticipated expiration: 2042-01-25
Also published as: CN114381160A

Abstract

The invention discloses a modified graphene oxide, wherein zinc is grafted on the surface of the modified graphene oxide through a silane coupling agent, one end of the silane coupling agent is connected with the graphene oxide, the other end of the silane coupling agent is connected with the zinc, and the surface of the modified graphene oxide has a hydrophobic micro-nano structure; preparing a silane coupling agent aqueous solution and an ethanol dispersion of zinc powder, mixing and reacting to obtain solid powder of which the silane coupling agent is grafted on the surface of the zinc powder, adding the obtained solid powder and graphene oxide into N, N-dimethylformamide for reaction, filtering and drying to obtain modified graphene oxide; the modified graphene oxide is used for a coating, the coating comprises, by weight, 20-40 parts of an active diluent, 40-70 parts of an oligomer containing acrylate double bonds, 1-5 parts of fluorine-containing acrylate, 0.5-5 parts of modified graphene oxide, 1-5 parts of a photoinitiator, 0.1-3 parts of a leveling agent, 0.1-3 parts of an antifoaming agent and 0.1-3 parts of a dispersing agent, and the obtained coating has excellent anticorrosion performance under triple effects of a labyrinth effect of the modified graphene oxide, a super-hydrophobic air cushion and electrochemical protection of zinc.

Description

Modified graphene oxide, preparation method thereof and coating

Technical Field

The invention relates to graphene oxide, in particular to modified graphene oxide, a preparation method thereof and a coating.

Background

Corrosion refers to the destruction of a material by chemical or electrochemical reaction with the environment. Such damage results in loss and failure of material properties, resulting in waste of resources and even equipment accidents. Both metallic and non-metallic materials can corrode from the action of environmental media. Anticorrosion principle 1 and shielding effect of the anticorrosion material: the physical principle of corrosion prevention is to isolate a protected material from an external corrosive medium by using a corrosion-prevention coating, and a film-forming agent is used to obtain a compact corrosion-prevention coating to isolate the damage of a corrosive substance to the protected material, namely, the shielding effect. 2. Corrosion inhibition: the chemical principle of corrosion prevention is to neutralize harmful acid-base substances into neutral harmless substances so as to protect materials in the corrosion-resistant coating from being damaged by the corrosive substances. 3. Chemical action: the electrochemical action of corrosion prevention means that some special substances are added into the antirust coating, so that when water and oxygen pass through the antirust coating, a reaction can be generated to form corrosion prevention ions, the surfaces of metals such as steel and the like are passivated, and the aim of corrosion prevention is achieved. The anticorrosion mechanism of the anticorrosive paint is that a shielding layer is formed on the surface of the metal to prevent water and oxygen from contacting with the surface of the metal, if the corrosion inhibitor anticorrosive paint is added into the paint, the anticorrosive paint has the function of corrosion retarding, and when the electrochemically active pigment and filler are added into the paint, the paint has the function of barrier and electrochemical protection, such as zinc-rich primer.

Graphene oxide is a novel two-dimensional material with a single-layer sheet structure formed by carbon atoms, has high strength, good toughness, large specific surface area and good chemical and thermal stability, and has certain advantages in metal corrosion prevention due to the characteristics. The lamellar structures of the graphene oxide are stacked and staggered layer by layer, a complex network shielding structure can be formed in the coating, infiltration, permeation and diffusion of corrosive media, namely a labyrinth effect, can be effectively inhibited, and the physical barrier property of the coating can be improved, so that corrosion is slowed down.

When the graphene oxide is applied to the coating, due to pi-pi coupling of the graphene oxide, the graphene oxide is easy to agglomerate and is easy to agglomerate due to large van der Waals force and high specific surface area. After the graphene oxide is agglomerated, a labyrinth permeation path with a barrier effect is not formed in a coating corresponding to the coating, the compactness of the coating is reduced after the graphene oxide is agglomerated, and pores are formed in an agglomeration area to aggravate permeation of corrosive gas, so that corrosion of the base material is accelerated. In addition, the agglomerated graphene oxide is directly connected with the base material to form the primary battery, so that the base material is promoted to be corroded in advance.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide modified graphene oxide capable of inhibiting the agglomeration of graphene oxide; the second purpose of the invention is to provide a preparation method of the modified graphene oxide, and the third purpose of the invention is to provide a coating containing the modified graphene oxide.

The technical scheme is as follows: according to the modified graphene oxide, zinc is grafted on the surface of the graphene oxide through a silane coupling agent, one end of the silane coupling agent is connected with the graphene oxide, and the other end of the silane coupling agent is connected with the zinc; the surface of the modified graphene oxide has a hydrophobic micro-nano structure.

The graphene oxide has micron-scale folds, and the surface of the modified graphene oxide is attached with nano zinc particles to form a nano mastoid structure and a hydrophobic micro-nano structure similar to the lotus leaf surface. The hydrophobic structure is easy to damage under the action of external force, the modified graphene oxide provided by the invention fixes zinc powder on the surface of the graphene oxide in a covalent bond mode through a silane coupling agent, the combination is relatively stable, and the hydrophobic structure has certain wear resistance.

The mass ratio of the zinc to the silane coupling agent to the graphene oxide is 1.03-0.08. The silane coupling agent is used as a connector of zinc powder and graphene oxide, the grafting efficiency between the zinc powder and the graphene oxide is influenced by the dosage of the silane coupling agent, when the dosage of the silane coupling agent is too low, less zinc is grafted on the surface of the graphene oxide, when the dosage of the silane coupling agent is too much, a self-condensation reaction is easy to occur, the silane coupling agent and the zinc are not favorably grafted, and the formation of a hydrophobic micro-nano structure on the surface of the modified graphene oxide is not favorably realized under the two conditions; when the addition amount of the graphene oxide is too much, the grafting amount of the zinc powder on the surface of the graphene oxide is relatively small, and when the use amount of the graphene oxide is too low, the excessive modified zinc powder is easily caused, and the modified zinc powder cannot be effectively grafted on the surface of the graphene, so that the formation of a hydrophobic micro-nano structure on the surface of the modified graphene oxide is influenced.

The preparation method of the modified graphene oxide is characterized by comprising the following steps:

(1) Preparing a silane coupling agent aqueous solution, adjusting the pH value to 8-10, and stirring to prehydrolyze the silane coupling agent in water; the pH value of the system is adjusted to be alkaline, alkoxy silicon in the silane coupling agent is hydrolyzed to form a silanol bond, silanol is easily dehydrated and condensed to form insoluble substances when the pH value is too high and the alkalinity is too strong or too low and the acidity is too weak, and the reaction speed is too slow when the pH value is neutral, so that the production is not facilitated. The hydrolysis equation is as follows (taking gamma-aminopropyltriethoxysilane KH550 silane coupling agent as an example):

(2) Adding zinc powder into ethanol to obtain dispersion.

(3) Mixing the liquid of (1) and (2), and reacting for 1-4 hours at 40-70 ℃; in the reaction process, a silanol group in the silane coupling agent and a hydroxyl group on the surface of the zinc powder are subjected to dehydration condensation and are connected to the surface of the zinc powder through a covalent bond, the reaction is slow when the reaction temperature is too low, and the silane coupling agent can be hydrolyzed automatically when the temperature is too high; centrifuging the reaction solution after the reaction is finished, washing to remove the unreacted silane coupling agent, and drying to obtain solid powder of which the silane coupling agent is grafted on the surfaces of the zinc powder particles; the reaction equation is as follows (taking gamma-aminopropyl triethoxy silane KH550 silane coupling agent as an example):

(4) Adding the solid powder prepared in the step (3) into N, N-Dimethylformamide (DMF), dispersing, adding graphene oxide, continuing to disperse uniformly, heating to 80-150 ℃, reacting for 4-8 hours, filtering, and drying to obtain modified graphene oxide solid powder; DMF is a good solvent of graphene oxide, is beneficial to the dispersion stability of the graphene oxide, and has a high boiling point and is suitable for medium-high temperature reaction; the reaction temperature is controlled to be 80-150 ℃, at the temperature, an amino functional group at the other end of the silane coupling agent and an epoxy functional group in the graphene oxide are subjected to ring-opening reaction, the graphene oxide and the zinc powder are connected together through the silane coupling agent, the reaction temperature is too low to facilitate the reaction, and the molecular structure of the silane coupling agent is easily damaged when the reaction temperature is too high. The reaction equation is as follows (taking gamma-aminopropyl triethoxy silane KH550 silane coupling agent as an example):

preferably, the mass fraction of the silane coupling agent aqueous solution in the step (1) is 3-20%; when the content of the silane coupling agent is too high, silanol after hydrolysis of the silane coupling agent is subjected to polycondensation, and the reaction efficiency is low due to too low content.

Preferably, the mass fraction of the zinc powder in the dispersion liquid in the step (2) is 5-25%; too low zinc powder content can lead to reduced production efficiency, and too high zinc powder content is not beneficial to the grafting reaction.

Preferably, in the step (4), the mass of the N, N-dimethylformamide is 50-70 times of the total mass of the solid powder, so that the reaction efficiency is reduced due to excessive solvent, the solvent is too little, and the dispersion is not uniform, which is not favorable for the reaction.

The coating disclosed by the invention contains the modified graphene oxide.

The coating comprises, by weight, 20-40 parts of an active diluent, 40-70 parts of an oligomer containing acrylate double bonds, 1-5 parts of fluorine-containing acrylate, 0.5-5 parts of modified graphene oxide, 1-5 parts of a photoinitiator, 0.1-3 parts of a leveling agent, 0.1-3 parts of an antifoaming agent, and 0.1-3 parts of a dispersant. Wherein the oligomer containing acrylate double bond and the reactive diluent are subjected to polymerization reaction under the action of a photoinitiator and illumination. The modified graphene oxide has a hydrophobic micro-nano structure, and is beneficial to formation of super-hydrophobic property on the surface of a coating after the coating is coated; the graphene oxide serves as a blocking filler in the coating, and the formation of a labyrinth effect of the graphene oxide is facilitated; in addition, the zinc powder grafted on the modified graphene can play an electrochemical protection role on the substrate. The reactive diluent acts to reduce the viscosity of the coating. The fluoroacrylate is used to reduce the surface energy of the coating.

Preferably, the oligomer is one or more of epoxy acrylate, polyurethane acrylate and polyester acrylate.

Preferably, the photoinitiator is one or more of a free radical type initiator 2-hydroxy-2-methyl-1-phenyl-1-acetone, 1-hydroxycyclohexyl phenyl ketone, (2,4,6-trimethylbenzoyl chloride) diphenyl phosphine oxide and phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide.

The preparation method of the coating comprises the following steps:

(1) Adding a reactive diluent into the oligomer to disperse the oligomer into a uniform and stable solution;

(2) Adding a dispersing agent, fluorine-containing acrylate, modified graphene oxide, a leveling agent and a defoaming agent into the solution prepared in the step (1), and uniformly dispersing; grinding by a sand mill to fully mix solid and liquid to form uniform dispersion liquid;

(3) Adding photoinitiator, and avoiding ultraviolet light from dispersing uniformly at normal temperature to prevent polymerization reaction from being initiated under ultraviolet light.

After the coating is sprayed, an ultraviolet lamp is used for irradiating to enable the photoinitiator to crack to generate free radicals, and the free radicals initiate polymerization reaction to form the coating.

The invention mechanism is as follows: according to the invention, graphene oxide is modified, and nano zinc particles are grafted on the surface of graphene oxide, so that on one hand, the graphene oxide agglomeration can be inhibited after the nano zinc particles are grafted on the surface of the graphene oxide, and the zinc powder particles grafted on the surface of the graphene oxide hinder the stacking of graphene oxide lamella, so that pi-pi conjugation cannot be formed between the graphene oxide lamellae, thus the agglomeration of the graphene oxide can be prevented, the uniform distribution of the graphene oxide in the coating is promoted, and the labyrinth effect of the graphene oxide is enhanced; on the other hand, under the supporting action of graphene oxide, a hydrophobic micro-nano structure can be formed on the surface of the graphene oxide grafted with zinc powder, air can be wrapped in the hydrophobic micro-nano structure to form an air film, a corrosive medium is isolated from a metal substrate, and water vapor is prevented from permeating into the surface of the substrate, so that the redox reaction of metal is effectively reduced, and the corrosion is prevented, namely the air cushion effect; meanwhile, zinc grafted on the graphene oxide can play an electrochemical protection role on the base material. The coating has excellent corrosion resistance under the triple effects of the labyrinth effect of the modified graphene oxide, the air cushion effect of the hydrophobic micro-nano structure and the electrochemical protection of zinc.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: (1) After the nano zinc particles are grafted on the surface of the modified graphene oxide, the graphene agglomeration can be inhibited, and the labyrinth effect of the graphene oxide is enhanced; (2) The surface of the modified graphene oxide has a hydrophobic micro-nano structure and super-hydrophobic property; (3) The preparation method of the modified graphene oxide is simple and easy to operate; (4) The coating contains modified graphene oxide, so that after the coating forms a coating, the hydrophobic angle is 158-168 degrees, the fog-salt resistant time is 500-600 hours, and the coating has excellent corrosion resistance; (5) the preparation method of the coating is simple; (6) The coating is a photo-curing coating, and has the advantages of high curing speed, no solvent volatilization and mild curing conditions.

Drawings

Fig. 1 is a scanning electron microscope image of modified graphene oxide prepared in example 1 of the present invention;

FIG. 2 is a graph of the energy spectrum analysis of the modified graphene oxide prepared in example 1 of the present invention;

fig. 3 is a thermogravimetric analysis diagram of the modified graphene oxide prepared in example 1 of the present invention.

Detailed Description

The technical scheme of the invention is further explained by combining the attached drawings.

Example 1

The preparation method of the modified graphene oxide comprises the following steps:

(1) Preparing gamma-aminopropyl triethoxysilane KH550 (silane coupling agent) aqueous solution with the mass fraction of 3%, adjusting the pH value to 8, and carrying out ultrasonic treatment for 20min to prehydrolyze the silane coupling agent in water;

(2) Adding zinc powder into ethanol to prepare dispersion liquid containing 5 mass percent of zinc powder;

(3) Adding the liquid prepared in the step (1) into the liquid prepared in the step (2), reacting for 4 hours at 40 ℃, centrifuging, washing with ethanol to remove unreacted silane coupling agent, and drying to obtain solid powder grafted on the surface of the zinc powder by the silane coupling agent, namely the silane coupling agent modified zinc powder;

(4) Adding the solid prepared in the step (3) into N, N-dimethylformamide, dispersing, adding graphene oxide, continuously dispersing uniformly, heating to 80 ℃ for reacting for 8 hours, filtering, and drying to obtain modified graphene oxide; wherein the mass of the N, N-dimethylformamide is 50 times of the total mass of the solid powder;

wherein the mass ratio of the zinc powder to the silane coupling agent to the graphene oxide is 1.

Example 2

(1) Preparing an N- (beta-aminoethyl) -3-aminopropyl methyl dimethoxy silane KH602 (silane coupling agent) aqueous solution with the mass fraction of 15%, adjusting the pH value to 9, and carrying out ultrasonic treatment for 20min to prehydrolyze the silane coupling agent in water;

(2) Adding zinc powder into ethanol to prepare a dispersion liquid containing 15% of the zinc powder by mass;

(3) Adding the liquid prepared in the step (1) into the liquid prepared in the step (2), reacting for 2 hours at 55 ℃, centrifuging, washing with ethanol to remove unreacted silane coupling agent, and drying to obtain solid powder of which the silane coupling agent is grafted on the surface of the zinc powder, namely the silane coupling agent modified zinc powder;

(4) Adding the solid prepared in the step (3) into N, N-dimethylformamide, dispersing, adding graphene oxide, continuously and uniformly dispersing, heating to 105 ℃, reacting for 6 hours, filtering, and drying to obtain modified graphene oxide; wherein the mass of the N, N-dimethylformamide is 60 times of the total mass of the solid powder;

wherein the mass ratio of the zinc powder to the silane coupling agent to the graphene oxide is 1.06.

Example 3

(1) Preparing 20 mass percent of N- (beta-aminoethyl) -3-aminopropyltrimethoxysilane KH792 (silane coupling agent), adjusting the pH value to 10, and carrying out ultrasonic treatment for 20min to prehydrolyze the silane coupling agent in water;

(2) Adding zinc powder into ethanol to prepare a dispersion liquid containing 25% of the zinc powder by mass;

(3) Adding the liquid prepared in the step (1) into the liquid prepared in the step (2), reacting for 1 hour at 70 ℃, centrifuging, washing with ethanol to remove unreacted silane coupling agent, and drying to obtain solid powder of which the silane coupling agent is grafted on the surface of the zinc powder, namely the silane coupling agent modified zinc powder;

(4) Adding the solid prepared in the step (3) into N, N-dimethylformamide, dispersing, adding graphene oxide, continuously and uniformly dispersing, heating to 150 ℃, reacting for 4 hours, filtering, and drying to obtain modified graphene oxide; wherein the mass of the N, N-dimethylformamide is 70 times of the total mass of the solid powder;

wherein the mass ratio of the zinc powder to the silane coupling agent to the graphene oxide is 1.08.

Comparative example 1

On the basis of example 2, the mass ratio of zinc powder, silane coupling agent and graphene oxide was adjusted to 2.06.

Comparative example 2

On the basis of example 2, the mass ratio of zinc powder, silane coupling agent and graphene oxide was adjusted to 1.

Comparative example 3

Example 4

The coating comprises, by weight, 20 parts of triethylene glycol diacrylate (reactive diluent), 40 parts of epoxy acrylate (oligomer), 1 part of fluorine-containing acrylate, 0.5 part of modified graphene oxide, 1 part of 2-hydroxy-2-methyl-1-phenyl-1-acetone (photoinitiator), 0.1 part of BYK377 (flatting agent), 0.1 part of BYK1790 (defoaming agent) and 0.1 part of BYK2013 (dispersant); wherein the modified graphene oxide is the modified graphene oxide prepared in example 1.

The preparation method of the coating comprises the following steps: (1) Adding a reactive diluent into the oligomer to disperse into a uniform and stable solution; (2) Adding a dispersing agent, fluorine-containing acrylate, modified graphene oxide, a leveling agent and a defoaming agent into the solution prepared in the step (1) in sequence, and uniformly dispersing; (3) Adding photoinitiator, and dispersing uniformly at normal temperature under the condition of avoiding ultraviolet light.

Example 5

The coating comprises, by weight, 30 parts of hydroxyethyl acrylate (a reactive diluent), 55 parts of polyurethane acrylate (an oligomer), 3 parts of fluorine-containing acrylate, 3.5 parts of modified graphene oxide, 3 parts of 1-hydroxycyclohexyl phenyl ketone, 2 parts of BYK377 (a leveling agent), 2 parts of BYK1790 (an antifoaming agent) and 2 parts of BYK2013 (a dispersing agent); wherein the modified graphene oxide is the modified graphene oxide prepared in example 2.

The preparation of the coating was the same as in example 4.

Example 6

The coating comprises, by weight, 40 parts of ethoxyethoxyethyl acrylate (active diluent), 70 parts of epoxy acrylate and polyester acrylate, 5 parts of fluorine-containing acrylate, 5 parts of modified graphene oxide, (2,4,6-trimethylbenzoyl chloride) diphenylphosphine oxide and 5 parts of phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide (photoinitiator), 3 parts of BYK377 (leveling agent), 3 parts of BYK1790 (defoaming agent) and 3 parts of BYK2013 (dispersant); wherein the modified graphene oxide is the modified graphene oxide prepared in example 3.

The preparation of the coating was carried out as in example 4.

Comparative example 4

On the basis of the embodiment 5, the modified graphene oxide is changed into the common graphene oxide, and the rest conditions are not changed.

Comparative example 5

On the basis of example 5, the modified graphene oxide was changed to zinc powder, and the remaining conditions were unchanged.

Comparative example 6

On the basis of example 5, the modified graphene oxide prepared in comparative example 1 was used as the modified graphene oxide, and the rest conditions were unchanged.

Comparative example 7

On the basis of example 5, the modified graphene oxide prepared in comparative example 2 was used as the modified graphene oxide, and the rest conditions were unchanged.

Comparative example 8

On the basis of example 5, the modified graphene oxide prepared in comparative example 3 is adopted as the modified graphene oxide, and the rest conditions are unchanged.

Structural characterization of modified graphene oxide

As shown in fig. 1, it can be seen from a scanning electron microscope image that graphene oxide has micrometer-scale wrinkles, and a large number of nanoparticles are attached to the surface of graphene oxide to form a nanometer-scale "papilla" structure, which is similar to a hydrophobic micro-nano structure on the surface of a lotus leaf, i.e., the modified graphene oxide surface has a hydrophobic micro-nano structure.

From the spectral data of fig. 2, it can be seen that the nanoparticles contain a large amount of zinc element, indicating that the nanoparticles are zinc powder particles.

As can be seen from FIG. 3, the silane coupling agent modified zinc powder heated to 400 ℃ had almost no weight loss, while the boiling point of gamma-aminopropyltriethoxysilane KH550 (silane coupling agent) was 217 ℃, indicating that there was no free KH550 in the modified zinc powder. The thermal weight loss of the graphene oxide at 250 ℃ is 40%, the ratio of the graphene oxide in the modified mixture is about 50%, the theoretical thermal weight loss is 20%, and fig. 3 shows that the actual thermal weight loss of the modified graphene oxide is 5%. This is because the thermal stability is improved after the epoxy group on the surface of the graphene oxide is modified to react with the amino group in KH550. The data in fig. 2 and fig. 3 show that zinc powder is effectively grafted on the surface of graphene oxide through KH550.

Paint Performance testing

The coatings of examples 4-6 and comparative examples 4-8 were coated on the surface of a carbon steel substrate, the coating on the surface of the substrate was irradiated with an ultraviolet lamp at normal temperature, after the coating on the surface of the substrate was completely dried, irradiation was stopped, and the coating performance was tested after standing at normal temperature for 24 hours.

The hydrophobic angle and fog salt resistance time of the cured coating were tested, and the hydrophobic angle was tested using a contact angle measuring instrument (OCA 20). The salt spray resistance is tested by using a salt spray corrosion test box, the salt spray test is tested according to GB/T110125-2012, and the test results are shown in Table 1.

TABLE 1 comparison of coating Properties of different examples

Name (R)	Angle/degree of hydrophobicity	Angle/degree of drainage after 90 times of rubbing	Salt spray resistance time/hour
				Example 4	158	150	500
Example 5	163	156	600
				Example 6	168	158	550
Comparative example 4	105	95	120
				Comparative example 5	102	93	72
Comparative example 6	136	95	360
				Comparative example 7	98	94	144
Comparative example 8	112	93	268

The larger the hydrophobic angle is, the stronger the hydrophobicity of the coating is, the more difficult the water vapor is to penetrate into the coating, so the better the corrosion resistance is, and the super-hydrophobic property of the coating is generally realized by the combined action of a hydrophobic structure and low surface energy. The coating disclosed by the invention contains modified graphene oxide with a hydrophobic micro-nano structure, so that the coating has super-hydrophobic performance. Generally, a hydrophobic structure is easily damaged under the action of an external force, while zinc powder modified graphene oxide fixes zinc powder on the surface of graphene oxide in a covalent bond mode through a silane coupling agent, so that the combination is relatively stable, and the hydrophobic structure has certain wear resistance.

As can be seen from examples 4 to 5 in table 1, the hydrophobicity of the coating material increases with the increase in the amount of the modified graphene oxide and the fluorine-containing acrylate. The salt spray resistance is increased and then reduced along with the increase of the using amount of the modified graphene oxide, because the content of the modified graphene oxide is increased, and the content of the oligomer and the reactive diluent is relatively reduced, the compactness of a coating formed after the coating is cured is reduced, and the corrosion resistance is slightly reduced.

In the comparative example 4, the modified graphene is replaced by the common graphene oxide, the common graphene oxide does not have a hydrophobic micro-nano structure, the coating is applied to a coating, the coating does not have super-hydrophobic performance, the water vapor barrier property is poor, and meanwhile, the graphene oxide is not modified and is easy to agglomerate, so that the salt spray resistance of the coating is poor.

In comparative example 5, the modified graphene oxide was replaced with zinc powder, the coating did not contain the modified graphene oxide, and the coating did not have super-hydrophobic property after curing, and in addition, the coating did not have the barrier effect of graphene oxide, and corrosive media could directly permeate into the surface of the substrate, so the corrosion resistance was poor.

In comparative example 6, the coating was prepared using the modified graphene oxide prepared in comparative example 1. In comparative example 1, the zinc powder was excessive in the process of preparing the modified graphene oxide, so that the excessive zinc powder could not be grafted on the surface of the graphene oxide by the silane coupling agent, but was combined with the graphene oxide by adsorption. The modified graphene is used for the coating, and the proportion of the modified graphene with the hydrophobic micro-nano structure is relatively reduced, so that the hydrophobicity and the salt spray resistance of the coating are reduced. The zinc powder adsorbed on the surface of the graphene oxide is not in covalent bond connection with the graphene, and is easy to fall off when being rubbed by external force, so that the prepared coating is poor in wear resistance.

In comparative example 7, the coating was prepared using the modified graphene oxide prepared in comparative example 2. In comparative example 2, excessive silane coupling agent in the process of preparing modified graphene oxide causes the silane coupling agent to be easy to generate polycondensation reaction, so that zinc powder is not favorable for grafting on the surface of graphene oxide, and a hydrophobic micro-nano structure cannot be formed. The modified graphene oxide is used for coating to form a coating, and the hydrophobicity, the wear resistance and the corrosion resistance of the coating are all reduced.

In comparative example 8, the coating was prepared using the modified graphene oxide prepared in comparative example 3. In the comparative example 3, in the process of preparing the modified graphene oxide, the graphene oxide is excessive, the relative grafting rate of zinc powder is low, and a hydrophobic micro-nano structure cannot be formed. The modified graphene oxide is used for coating to form a coating, and the hydrophobicity, the wear resistance and the corrosion resistance of the coating are reduced.

Claims

1. The modified graphene oxide is characterized in that zinc is grafted on the surface of the graphene oxide through a silane coupling agent, one end of the silane coupling agent is connected with the graphene oxide, the other end of the silane coupling agent is connected with the zinc, and the surface of the modified graphene oxide has a hydrophobic micro-nano structure; wherein, silanol groups in the silane coupling agent and hydroxyl groups on the surface of the zinc powder are subjected to dehydration condensation and are connected to the surface of the zinc powder through covalent bonds; performing ring-opening reaction on an amino functional group at the other end of the silane coupling agent and an epoxy functional group in the graphene oxide, and connecting the graphene oxide and the zinc powder together through the silane coupling agent; the mass ratio of the zinc to the silane coupling agent to the graphene oxide is 1.03 to 0.08; the modified graphene oxide is prepared by the following method: (1) Preparing a silane coupling agent aqueous solution, adjusting the pH value to 8 to 10, and stirring to prehydrolyze the silane coupling agent in water; (2) adding zinc powder into ethanol to prepare a dispersion liquid; (3) Mixing the liquids in the steps (1) and (2), reacting at 40-70 ℃ for 1~4 hours, centrifuging, washing to remove unreacted silane coupling agent, and drying to obtain solid powder of the silane coupling agent grafted on the surface of the zinc powder; (4) Adding the solid powder into N, N-dimethylformamide, dispersing, then adding the graphene oxide solid powder, continuing to disperse uniformly, heating to 80-150 ℃ to react for 4~8 hours, filtering, and drying to obtain the modified graphene oxide.

2. The modified graphene oxide according to claim 1, wherein in the step (1), the mass fraction of the aqueous solution of the silane coupling agent is 3 to 20%.

3. The modified graphene oxide according to claim 1, wherein in the step (2), the mass fraction of the zinc powder in the dispersion liquid is 5 to 25%.

4. The modified graphene oxide according to claim 1, wherein the mass of N, N-dimethylformamide in step (4) is 50 to 70 times of the total mass of the solid powder.

5. A coating, characterized by: comprising the modified graphene oxide according to claim 1.

6. The coating according to claim 5, characterized by comprising 20 to 40 parts of active diluent, 40 to 70 parts of oligomer containing acrylate double bonds, 1~5 parts of fluorine-containing acrylate, 0.5 to 5 parts of modified graphene oxide, 1~5 parts of photoinitiator, 0.1 to 3 parts of leveling agent, 0.1 to 3 parts of defoaming agent and 0.1 to 3 parts of dispersing agent by weight.

7. The coating of claim 6, wherein the oligomer is one or more combinations of epoxy acrylate, urethane acrylate, and polyester acrylate.

8. The coating of claim 6, wherein the photoinitiator is one or more of the group consisting of the free radical initiator 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexyl phenyl ketone, (2,4,6-trimethylbenzoyl chloride) diphenyl phosphine oxide, and phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide.