CN113150640B

CN113150640B - Cerium ion-loaded two-dimensional nanomaterial-based self-healing barrier dual-function coating and preparation method and application thereof

Info

Publication number: CN113150640B
Application number: CN202110556503.7A
Authority: CN
Inventors: 暴宁钟; 姚环东; 沈丽明; 燕克兰; 吴健
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2021-05-21
Filing date: 2021-05-21
Publication date: 2021-10-26
Anticipated expiration: 2041-05-21
Also published as: CN113150640A

Abstract

The invention discloses a cerium ion loaded two-dimensional nanomaterial-based self-healing barrier dual-function coating and a preparation method and application thereof, and the coating comprises 2-10 parts of a cerium ion loaded two-dimensional nanomaterial, 40-60 parts of bio-based resin, 5-15 parts of polyvinyl acetal, 5-10 parts of polymethylhydrosiloxane, 4-10 parts of a curing agent and 0.005-0.03 part of an anti-flash rust agent. The coating prepared by the invention takes the bio-based resin as a main component, reduces the dependence on petrochemical resources and is more environment-friendly, and the rare earth metal is taken as a corrosion inhibitor, so that the pollution to the environment is less. The coating prepared by the invention has specific polydopamine and corrosion inhibitor release behavior under corresponding pH conditions, and a bio-based coating with long-term stable and efficient corrosion resistance can be obtained by adjusting the contents of the two-dimensional nano material, the polydopamine and the cerium ions.

Description

Cerium ion-loaded two-dimensional nanomaterial-based self-healing barrier dual-function coating and preparation method and application thereof

Technical Field

The invention belongs to the field of coatings, and relates to a cerium ion-loaded two-dimensional nanomaterial-based self-healing barrier dual-function coating, and a preparation method and application thereof.

Background

Metal materials occupy an important position in the field of materials due to excellent mechanical properties and processability, but metal corrosion suffered in practical application brings huge economic loss, environmental damage and potential safety problems. The application of organic coatings to metal surfaces is the most common and effective method of metal protection. However, pure polymer coatings are difficult to achieve long-term effective corrosion protection in practical environmental applications due to inherent defects. The addition of fillers to pure polymer coatings is a reliable modification method that can effectively improve the long-term corrosion resistance of the coatings.

The traditional filler plays a role in obstructing and prolonging the permeation path of corrosive media in the coating, thereby improving the corrosion resistance of the coating. However, in practical applications, the area of the coating after breakage can greatly reduce the metal protection capability of the coating. In fact, a coating with long-term high-efficiency corrosion resistance must have both high barrier property and self-healing corrosion resistance. The main two mechanisms for realizing the self-repairing of the coating are that the physical barrier of the coating is recovered by closing the defects of the damaged area of the coating, or the corrosion reaction at the defects of the coating is inhibited by adding a corrosion inhibitor. Conventional corrosion inhibitors such as chromate and the like have excellent corrosion inhibiting effects, but have been banned in industrial production due to their toxicity. Under the development background of increasingly advocating green environmental protection, some rare earth metals and compounds thereof are considered to be corrosion inhibitors with development prospects. However, coating defects due to the incompatibility of the corrosion inhibitor and the polymer instead provide a new permeation pathway for the corrosive medium.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to solve the technical problem of incompatibility of a corrosion inhibitor and a polymer in the prior art, and provides a cerium ion loaded two-dimensional nano material based self-healing barrier dual-function coating, wherein a high-performance bio-based coating is obtained by adding a cerium ion loaded two-dimensional nano material into a bio-based coating.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a cerium ion supported two-dimensional nanomaterial-based self-healing barrier dual-function coating comprises the following components in parts by mass:

2-10 parts of a cerium ion-loaded two-dimensional nanomaterial;

40-60 parts of bio-based resin;

5-15 parts of polyvinyl acetal;

5-10 parts of polymethylhydrosiloxane;

4-10 parts of a curing agent;

0.005-0.03 part of flash rust inhibitor.

The cerium ion-loaded two-dimensional nanomaterial is prepared by the following steps:

(1) fully dispersing a two-dimensional nano material in deionized water to obtain a mixture A;

(2) adding dopamine into the mixture A, and uniformly mixing to obtain a mixture B;

(3) adding a trihydroxymethyl aminomethane buffer solution into the mixture B, adjusting the pH value to 7-10, and fully mixing to obtain a mixture C;

(4) adding water-soluble cerium salt into the mixture C, adjusting the pH value to 3-7, and fully mixing to obtain a mixture D;

(5) and centrifugally washing the mixture D by using deionized water to remove unreacted impurities, and drying to obtain the catalyst.

Specifically, in the step (1), the two-dimensional nanomaterial is selected from any one or a combination of more than two of hexagonal boron nitride, graphene, molybdenum disulfide, graphene oxide and tungsten disulfide; mixing the two-dimensional nano material and deionized water according to the mass ratio of 0.1-10%, and stirring for 5-30 minutes by combining ultrasound and machinery.

In the step (2), the mass ratio of the dopamine to the two-dimensional nano material in the step (1) is 5: 1-1: 5, ultrasonic and mechanical stirring for 5-60 minutes.

In the step (3), the mass of the trihydroxymethyl aminomethane in the trihydroxymethyl aminomethane buffer solution is 2% -10% of the mass of the two-dimensional nano material, and ultrasonic and mechanical mixing is combined for 1-10 minutes; and after the pH value is adjusted, ultrasonic and mechanical stirring are combined for 10-30 hours.

In the step (4), the water-soluble cerium salt is selected from any one of cerium methanesulfonate, cerium sulfate, cerium phosphate, cerium acetate and cerium nitrate; the mass ratio of the water-soluble cerium salt to the two-dimensional nano material in the step (1) is 5: 1-1: 5, stirring for 1-10 minutes by combining ultrasound and machinery; after the pH value is adjusted, the mixture is stirred for 0.5 to 3 hours by ultrasonic and mechanical combination.

In the step (5), the centrifugation speed is 3000-10000 r/min, the centrifugation time is 3-10 minutes, and the drying temperature is controlled at 50-100 ℃.

Firstly, the dopamine-loaded two-dimensional nanomaterial is obtained through the adsorption effect of dopamine on the two-dimensional nanomaterial. Secondly, under the alkaline condition, dopamine undergoes oxidation-polymerization reaction to obtain the poly-dopamine-coated two-dimensional nanomaterial. And finally, the cerium ions are successfully loaded on the surface of the two-dimensional nano material coated by the polydopamine through the electrostatic attraction effect of the polydopamine and the cerium ions.

Strong adsorbability of dopamine to the two-dimensional nanomaterial and oxidative polymerization of dopamine under an alkaline condition to obtain the polydopamine-coated two-dimensional nanomaterial. And then the two-dimensional nano material with good cerium ion loading is obtained through the electrostatic attraction effect between the cerium ions and the polydopamine.

Preferably, the bio-based resin is selected from any one of bio-based polybenzoxazine resin, bio-based epoxy resin and bio-based phenolic resin.

Preferably, the curing agent is toluenesulfonic acid or cardanol aminal; the anti-flash rust agent is tripolyphosphate ester.

The invention further provides a preparation method of the cerium ion loaded two-dimensional nano material based self-healing barrier dual-function coating, which comprises the steps of firstly adding the bio-based resin, the polyvinyl acetal and the polymethylhydrosiloxane into the organic solvent for mixing, then adding the cerium ion loaded two-dimensional nano material for uniformly mixing, and finally adding the curing agent and the anti-flash rust agent for uniformly mixing.

Furthermore, the invention also claims the application of the cerium ion supported two-dimensional nanomaterial-based self-healing barrier bifunctional coating as a surface coating of a metal material.

The poly-dopamine-coated cerium ion-supported two-dimensional nano-material has a uniform arrangement direction in the coating. The wear resistance and corrosion resistance of the coating prepared on the surface of the metal material by the vertical suspension method are superior to those of the coating which is not prepared by the method, because the oriented cerium ion loaded two-dimensional nano material can provide a longer corrosion ion permeation path and can bear more external load under the same content.

Has the advantages that:

1. the two-dimensional nano material in the coating can play a passive barrier role in the bio-based coating, and can block and prolong the permeation path of corrosive media. Cerium ions can play an active self-healing role in the bio-based coating, which can adsorb on the cathode region and form hydroxide precipitates to suppress the reaction rate of the cathode. The polydopamine can play an additional role in protection in the bio-based coating, and can generate electrostatic attraction with metal ions of a protected metal substrate in an anode area to form a coordination complex. Under the alkaline pH condition, due to the electrostatic repulsion action between polydopamine and graphene oxide, the wrapped polydopamine film can be partially peeled off, so that free polydopamine is released. Under acidic conditions, the electrostatic attraction between polydopamine and cerium ions is reduced, resulting in an increase in the concentration of free cerium ions. Thus polydopamine and cerium ions have specific release behavior under different pH conditions.

2. The coating prepared by the invention takes the bio-based resin as a main component, reduces the dependence on petrochemical resources and is more environment-friendly, and takes the rare earth metal as a corrosion inhibitor, so that the pollution to the environment is less. The coating prepared by the invention has specific polydopamine and corrosion inhibitor release behavior under corresponding pH conditions, and a bio-based coating with long-term stable and efficient corrosion resistance can be obtained by adjusting the contents of the two-dimensional nano material, the polydopamine and the cerium ions.

Drawings

The foregoing and/or other advantages of the invention will become further apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

Fig. 1 is a graph of polydopamine release from graphene oxide-polydopamine after soaking for 24h under different pH conditions in example 3.

Fig. 2 is a graph of the release of cerium ions from graphene oxide-polydopamine-cerium ions after soaking for 24h under different pH conditions in example 3.

FIG. 3 is an electron microscope scan of (a) a pure bio-based epoxy coating (comparative example 1) and (b) a bio-based epoxy composite coating with added graphene oxide-polydopamine-cerium ions (example 2) with scratches after soaking in a 3.5 wt% aqueous sodium chloride solution for 24 hours, rinsing with deionized water and drying.

Detailed Description

The invention will be better understood from the following examples.

Example 1

(1) Respectively weighing hexagonal boron nitride and deionized water, mixing the hexagonal boron nitride and the deionized water according to the mass ratio of 1%, and mechanically stirring for 5 minutes by ultrasonic combination of 500r/min to obtain a mixture A; (2) adding dopamine into the mixture A, wherein the mass ratio of the dopamine to the hexagonal boron nitride is 5: 1, mechanically stirring for 30 minutes by combining ultrasonic and 500r/min to obtain a mixture B; (3) adding a trihydroxymethyl aminomethane buffer solution into the mixture B, wherein the mass of the trihydroxymethyl aminomethane is 2% of that of the hexagonal boron nitride, mechanically stirring for 5 minutes by ultrasonic combination at 500r/min, then adding a hydrochloric acid aqueous solution to adjust the pH value to 9, and mechanically stirring for 10 hours at 300r/min to obtain a mixture C; (4) adding cerium nitrate into the mixture C, wherein the mass ratio of the cerium nitrate to the hexagonal boron nitride is 5: 1, mechanically stirring for 5 minutes at 500r/min by ultrasonic combination, then adding a hydrochloric acid aqueous solution to adjust the pH value to 5, and stirring for 0.5 hour by ultrasonic combination to obtain a mixture D; (5) and (3) centrifugally washing the mixture D with deionized water for three times at the centrifugal speed of 3000r/min for 3min, and then drying in an oven at 50 ℃ for 10h to obtain the cerium ion-loaded two-dimensional nanomaterial.

Adding 45 parts of bio-based phenolic resin, 15 parts of polyvinyl acetal and 10 parts of polymethylhydrosiloxane into ethanol, and mechanically stirring for 60min at 1000r/min to obtain a mixture E; adding 3 parts of cerium ion-loaded hexagonal boron nitride into the mixture E, and mechanically stirring for 10min by ultrasonic combination at a speed of 500r/min to obtain a mixture F; adding 4 parts of p-toluenesulfonic acid and 0.01 part of tripolyphosphate into the mixture F, and mechanically stirring for 10min by ultrasonic combination at 500r/min to obtain a mixture G, namely the cerium ion-loaded two-dimensional nano material-based self-healing barrier dual-function coating; and (3) immersing a Q235 metal substrate into the mixture G, and then vertically hanging at 60 ℃ for 12h to obtain the directionally-arranged self-healing barrier dual-function coating with pH response release polydopamine and cerium ions.

Example 2

(1) Respectively weighing graphene oxide and deionized water, mixing the graphene oxide and the deionized water according to the mass ratio of 1%, and mechanically stirring for 5 minutes by ultrasonic combination at 800r/min to obtain a mixture A; (2) adding dopamine into the mixture A, wherein the mass ratio of the dopamine to the graphene oxide is 2: 1, mechanically stirring for 40 minutes at 700r/min by ultrasonic combination to obtain a mixture B; (3) adding a trihydroxymethyl aminomethane buffer solution into the mixture B, wherein the mass of the trihydroxymethyl aminomethane is 3% of that of the graphene, mechanically stirring for 5 minutes by ultrasonic combination at 1000r/min, then adding a hydrochloric acid aqueous solution to adjust the pH value to 8, and mechanically stirring for 16 hours at 500r/min to obtain a mixture C; (4) adding cerium sulfate into the mixture C, wherein the mass ratio of the cerium sulfate to the graphene is 3: 1, mechanically stirring for 5 minutes at 700r/min by ultrasonic combination, then adding a hydrochloric acid aqueous solution to adjust the pH value to 6, and stirring for 2 hours by ultrasonic combination to obtain a mixture D; (5) and centrifuging and washing the mixture D with deionized water for three times at the centrifugal speed of 5000r/min for 4min, and drying in an oven at the temperature of 60 ℃ for 12h to obtain the cerium ion-loaded graphene oxide.

Adding 50 parts of bio-based epoxy resin, 10 parts of polyvinyl acetal and 10 parts of polymethylhydrosiloxane into acetone, and mechanically stirring for 30min at 2000r/min to obtain a mixture E; adding 7 parts of cerium ion-loaded graphene oxide into the mixture E, and mechanically stirring for 10min by ultrasonic combination at 800r/min to obtain a mixture F; adding 10 parts of cardanol aminal and 0.005 part of tripolyphosphate into the mixture F, and mechanically stirring for 20min by ultrasonic combination at 700r/min to obtain a mixture G, namely the cerium ion-loaded two-dimensional nano material-based self-healing barrier dual-function coating; and (3) immersing a Q235 metal substrate into the mixture G, and then vertically hanging the substrate at 80 ℃ for 15 hours to obtain the directionally-arranged self-healing barrier dual-function coating with pH response release polydopamine and cerium ions.

Example 3

(1) Respectively weighing graphene oxide and deionized water, mixing the graphene oxide and the deionized water according to the mass ratio of 1%, and mechanically stirring for 6 minutes by ultrasonic combination at 1000r/min to obtain a mixture A; (2) adding dopamine into the mixture A, wherein the mass ratio of the dopamine to the graphene oxide is 1: 1, mechanically stirring for 50 minutes at 800r/min by ultrasonic combination to obtain a mixture B; (3) adding a trihydroxymethyl aminomethane buffer solution into the mixture B, wherein the mass of the trihydroxymethyl aminomethane is 5% of that of the graphene oxide, mechanically stirring for 10 minutes at 800r/min by ultrasonic combination, then adding a hydrochloric acid aqueous solution to adjust the pH value to 8, and mechanically stirring for 20 hours at 700r/min to obtain a mixture C; (4) adding cerium nitrate into the mixture C, wherein the mass ratio of the cerium nitrate to the graphene oxide is 1: 1, mechanically stirring for 8 minutes at 800r/min by ultrasonic combination, then adding a hydrochloric acid aqueous solution to adjust the pH value to 4, and stirring for 3 hours by ultrasonic combination to obtain a mixture D; (5) and centrifuging and washing the mixture D with deionized water for three times at the centrifuging speed of 6000r/min for 4min, and then drying in an oven at the temperature of 80 ℃ for 15h to obtain the cerium ion-loaded graphene oxide.

Adding 60 parts of bio-based polybenzoxazine resin, 10 parts of polyvinyl acetal and 6 parts of polymethylhydrosiloxane into xylene, and mechanically stirring for 20min at 3000r/min to obtain a mixture E; adding 10 parts of cerium ion-loaded two-dimensional nano material into the mixture E, and mechanically stirring for 20min by ultrasonic combination at 900r/min to obtain a mixture F; adding 5 parts of p-toluenesulfonic acid and 0.02 part of tripolyphosphate into the mixture F, and mechanically stirring for 30min by ultrasonic combination at 800r/min to obtain a mixture G, namely the cerium ion-loaded two-dimensional nano material-based self-healing barrier dual-function coating; and (3) immersing a Q235 metal substrate into the mixture G, and then vertically hanging the substrate at 150 ℃ for 18h to obtain the directionally-arranged self-healing barrier dual-function coating with pH response release polydopamine and cerium ions.

The solution (mixture C) with the graphene oxide-polydopamine nanoparticles was dispersed in deionized water, the pH was adjusted, and the solution was left for 24 hours and then subjected to uv spectroscopy, with the results shown in fig. 1. FIG. 1 shows that the absorbance of polydopamine at 286nm is related to the concentration of polydopamine. The absorption peak intensity of polydopamine gradually increased with increasing pH, indicating that alkaline pH promoted the release of polydopamine. Thus, polydopamine has a specific release behaviour under different pH conditions.

Meanwhile, the solution (mixture D) with the graphene oxide-polydopamine-cerium ion nanoparticles is dispersed in deionized water, the pH is adjusted, and an ultraviolet spectrum test is performed after the solution is left for 24 hours, and the result is shown in fig. 2. FIG. 2 shows that the absorbance of cerium ions at 252nm is related to the concentration of cerium ions. Under acidic conditions, an absorption peak appears in an ultraviolet spectrum of cerium ions, and the smaller the pH value is, the greater the intensity of the absorption peak is, which indicates that the acidic conditions promote the release of the cerium ions. Under alkaline conditions, no absorption peak appears in the ultraviolet spectrum of the cerium ions, which indicates that the alkaline conditions inhibit the release of the cerium ions. Thus, cerium ions have a specific release behavior under different pH conditions.

Comparative example 1

(1) Adding 50 parts of bio-based epoxy resin, 10 parts of polyvinyl butyral and 5 parts of polymethylhydrosiloxane into ethanol, and mechanically stirring for 50min at 900r/min to obtain a mixture A; (2) adding 8 parts of cardanol aminal and 0.03 part of tripolyphosphate into the mixture A, and mechanically stirring for 20min by ultrasonic combination at 1000r/min to obtain a mixture B; (3) the Q235 metal substrate was immersed in mixture B and then hung vertically at 70 ℃ for 15h to obtain a coating.

Comparative example 2

(1) Adding 45 parts of bio-based phenolic resin, 8 parts of polyvinyl butyral, 5 parts of polymethylhydrosiloxane and 3 parts of cerium nitrate into ethanol, and mechanically stirring for 60min at the speed of 800r/min to obtain a mixture A; (2) adding 5 parts of p-toluenesulfonic acid and 0.01 part of tripolyphosphate into the mixture A, and mechanically stirring for 30min by ultrasonic combination at 1000r/min to obtain a mixture B; (3) the Q235 metal substrate was immersed in mixture B and then hung vertically at 80 ℃ for 13h to obtain a coating.

The coating samples obtained in examples 1-3 and comparative examples 1-2 were tested for friction and corrosion performance, and the specific test method was as follows:

the experimental equipment used for the friction performance testing was a UMT-2 friction wear tester in the United states. The friction element is a GCr15 steel ball with the diameter of 10mm and the hardness of HRC 62-65. The experimental conditions are room temperature, external load 2N, reciprocating frequency 5Hz, reciprocating length 5mm, friction time 60min and sample thickness 85 +/-5 μm.

The corrosion performance was tested using electrochemical ac impedance techniques. The test was performed using a conventional three-electrode system, in which the reference electrode was a silver/silver chloride electrode, the counter electrode was a platinum sheet electrode, the sample to be tested was a working electrode, and the electrolyte was a 3.5 wt% aqueous solution of NaCl. In thatAfter the open-circuit potential of the coating is stabilized, setting the test frequency range to be 10^-2～10⁵Hz, the amplitude of the alternating voltage is 20 mV. The thickness of the sample is 85 +/-5 mu m, the test period is 200 days, and the experimental result is shown in table 1.

TABLE 1

As can be seen from the data in Table 1, the effect of directly adding cerium ions is not significantly improved. The promotion of the coating by the small amount of the cerium ion-loaded two-dimensional nano material is limited. Excessive cerium ion-loaded two-dimensional nanomaterial easily causes agglomeration, thereby reducing the lifting effect on the coating. In addition, compared with a pure coating, the performance of the composite coating only added with cerium ions is not improved much.

The bio-based epoxy resin composite coating added with graphene oxide-polydopamine-cerium ions in example 2 and the pure bio-based epoxy resin coating in comparative example 1 are taken, dried and cured, the coating is scratched through on the surface of the coating (the scratch size is 1mm × 10mm), the coating is soaked in 3.5 wt% sodium chloride aqueous solution, and after 24 hours, the coating is washed by deionized water and dried, and the coating is subjected to scanning shooting by an electron microscope, and the result is shown in fig. 3.

The results show that in the scratched areas of the pure bio-based epoxy coating, the corrosion products are mostly granular iron oxides. In the scratch area of the bio-based epoxy resin composite coating added with the graphene oxide-polydopamine-cerium ions, the shape of the corrosion product is converted into a sheet or plate-shaped substance, which shows that the polydopamine and cerium ions participate in the corrosion reaction and reduce the generation of iron oxide.

The invention provides a cerium ion supported two-dimensional nanomaterial-based self-healing barrier bifunctional coating, and a preparation method and an application concept and method thereof, and a plurality of methods and ways for realizing the technical scheme are provided. All the components not specified in the present embodiment can be realized by the prior art.

Claims

1. The cerium ion supported two-dimensional nanomaterial-based self-healing barrier dual-function coating is characterized by comprising the following components in parts by mass:

2-10 parts of a cerium ion-loaded two-dimensional nanomaterial;

40-60 parts of bio-based resin;

5-15 parts of polyvinyl acetal;

5-10 parts of polymethylhydrosiloxane;

4-10 parts of a curing agent;

0.005-0.03 part of flash rust inhibitor;

the two-dimensional nano material loaded with cerium ions is prepared by the following steps:

(5) centrifugally washing the mixture D by deionized water to remove unreacted impurities, and drying to obtain the catalyst;

in the step (1), the two-dimensional nano material is selected from any one or a composition of more than two of hexagonal boron nitride, graphene and graphene oxide; mixing a two-dimensional nano material and deionized water according to a mass ratio of 0.1-10%, and stirring for 5-30 minutes by combining ultrasound and machinery;

in the step (2), the mass ratio of the dopamine to the two-dimensional nano material in the step (1) is 5: 1-1: 5, stirring for 5-60 minutes by combining ultrasound and machinery;

in the step (3), the mass of the trihydroxymethyl aminomethane in the trihydroxymethyl aminomethane buffer solution is 2% -10% of the mass of the two-dimensional nano material, and ultrasonic and mechanical mixing is combined for 1-10 minutes; after the pH value is adjusted, ultrasonic and mechanical stirring are combined for 10-30 hours;

2. The cerium-ion-loaded two-dimensional nanomaterial-based self-healing barrier dual-function coating according to claim 1, wherein in the step (5), the centrifugation speed is 3000-10000 r/min, the centrifugation time is 3-10 minutes, and the drying temperature is controlled to be 50-100 ℃.

3. The cerium-ion-supported two-dimensional nanomaterial-based self-healing barrier bifunctional coating of claim 1, wherein the bio-based resin is selected from any one of bio-based polybenzoxazine resin, bio-based epoxy resin and bio-based phenolic resin; the curing agent is toluenesulfonic acid or cardanol aminal; the anti-flash rust agent is tripolyphosphate ester.

4. The preparation method of the cerium ion-loaded two-dimensional nanomaterial-based self-healing barrier dual-function coating as claimed in claim 1, wherein the preparation method comprises the steps of adding and mixing bio-based resin, polyvinyl acetal and polymethylhydrosiloxane into an organic solvent, adding and mixing the two-dimensional nanomaterial loaded with cerium ions, and adding and mixing the curing agent and the anti-flash rust agent to obtain the cerium ion-loaded two-dimensional nanomaterial-based self-healing barrier dual-function coating.

5. The application of the cerium ion supported two-dimensional nanomaterial-based self-healing barrier bifunctional coating as defined in claim 1 as a surface coating of a metal material.