A graphene oxide modified bio-based microcapsule, its preparation method and application

Abstract

The present invention belongs to the fields of graphene oxide materials, bio-based materials and self-healing coatings, and relates to a graphene oxide-modified bio-based microcapsule and its preparation method and application. The bio-based microcapsules of the present invention are microcapsule A and / or microcapsule B; both microcapsule A and microcapsule B include a capsule wall, a capsule core and an outer coating of the capsule wall; the capsule wall materials of microcapsule A and microcapsule B are the same, being polymethyl methacrylate, polysulfone or polylactic acid, and the outer coating materials of the capsule walls of microcapsule A and microcapsule B are the same, being a bio-based surfactant and GO grafted with amino molecules; the capsule core of microcapsule A includes a composition of a bio-based curing agent and GO grafted with the bio-based curing agent; the capsule core of microcapsule B includes a composition of a bio-based epoxy resin and GO grafted with the bio-based epoxy resin. The microcapsules prepared by the present invention can endow the coating with self-healing performance while improving the intrinsic barrier performance of the bio-based coating and enhancing the corrosion protection ability of the coating.

Description

Technical Field

[0001] The present invention belongs to the fields of graphene oxide materials, bio-based materials and self-healing coatings, and relates to a bio-based microcapsule modified by graphene oxide, a preparation method thereof and an application thereof. Background Art

[0002] Epoxy composite coatings have a barrier effect on the substrate due to their dense structure, and can hinder the penetration of corrosion factors, and are widely used in fields such as ocean ships, oil pipelines, and drilling platforms. However, most epoxy coating materials are petroleum-based, non-biodegradable and derived from non-renewable resources, which are likely to cause environmental pollution. With the increasing penetration of the concept of sustainable development, bio-based coatings represented by cardanol-based, castor oil-based, and soybean oil-based coatings have attracted people's attention.

[0003] However, there is still a certain gap in the anti-corrosion and mechanical properties between bio-based coatings and petroleum-based coatings. When exposed to the natural environment, the surface is more likely to be damaged by external forces to cause microcracks, greatly reducing the protection effect on the substrate, and the long-term anti-corrosion performance of the coating is severely challenged.

[0004] Self-healing coatings are one of the effective methods to extend the service life of coatings, which are divided into intrinsic self-healing and external self-healing. External self-healing mainly endows the coating with self-healing ability by loading fillers such as microcapsules, liquid core fibers, carbon nanotubes, etc. in the coating. Among them, microcapsules have been widely used due to their simple preparation process and high healing efficiency.

[0005] Existing microcapsules are mainly applied to petroleum-based coatings, and there are few specifically for bio-based coatings. In previous work, we prepared a microcapsule with a high bio-based content using cardanol-based healing agent and cardanol surfactant [Authorized Publication Number: CN115322613B]. The service life of the coating can be significantly improved through the self-healing effect. However, our experimental research found that when microcapsules are implanted in bio-based coatings, the petroleum-based polymethyl methacrylate as the capsule wall has general compatibility with bio-based materials and will form gaps with the coating. In addition, since the microcapsules encapsulate liquid core materials, they will become channels through which corrosion factors are easily penetrated. Therefore, although the above self-healing microcapsules are successfully added to bio-based coatings to endow the coatings with self-healing ability, the anti-corrosion and mechanical properties of the bio-based coatings themselves are greatly reduced. Moreover, the healing areas formed after the existing microcapsules rupture are also prone to become defects, affecting the overall performance of the coating.

[0006] GO, as a two-dimensional structural material, contains a large number of oxygen-containing functional groups: carboxyl (-COOH), epoxy group (-O-), and hydroxyl (-OH). It is easy to graft different functional groups and has been used as a filler with high barrier and mechanical properties in the field of anti-corrosion coatings. However, there are few relevant reports on its modification of microcapsules, especially in the field of modification of bio-based microcapsules. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to develop a microcapsule containing specific functionalized GO and bio-based healing agent and its efficient preparation technology applicable to bio-based microcapsules and bio-based epoxy coatings to improve the anti-corrosion and mechanical properties of bio-based coatings implanted with bio-based microcapsules, aiming at the problem that existing bio-based microcapsules cause the decline of anti-corrosion and mechanical properties of bio-based coatings.

[0008] Inventive idea: Modify and modify GO of a specific size by grafting different functional groups, adjust the hydrophilic and hydrophobic properties, and add them to the core and the outer layer of the capsule wall respectively. The core is a bio-based healing agent that has a repairing effect on the bio-based coating and modified GO grafted with the bio-based healing agent, which is encapsulated in the capsule wall material; when microcracks appear in the bio-based coating, the capsule wall of the microcapsule ruptures, releasing the core material, healing the cracked area. The modified GO material contained in the core is dispersed in the healing part to improve the anti-corrosion performance of the healing part and achieve self-healing of the coating; the outer layer of the capsule wall is modified GO (M-GO) grafted with amino molecules and a bio-based surfactant. M-GO is evenly inserted and wrapped on the outer surface of the capsule wall through electrostatic adsorption. The amino group on the modified GO can react with the bio-based resin, enhancing the binding force between the microcapsule and the bio-based coating, so that when microcracks occur in the coating, the microcapsule can be better opened, thereby releasing the healing factor and inhibiting the penetration of corrosion factors.

[0009] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0010] The present invention discloses a bio-based microcapsule modified by graphene oxide. The bio-based microcapsule is microcapsule A and / or microcapsule B; both microcapsule A and microcapsule B include a capsule wall, a core, and an outer layer of the capsule wall; the capsule wall materials of microcapsule A and microcapsule B are the same, the outer layer materials of the capsule wall of microcapsule A and microcapsule B are the same, and the core materials of microcapsule A and microcapsule B are different;

[0011] The capsule wall, its material includes polymethyl methacrylate, polysulfone or polylactic acid, preferably polymethyl methacrylate;

[0012] The outer layer of the capsule wall, its material includes a bio-based surfactant and GO grafted with amino molecules (M-GO);

[0013] The described microcapsule A, whose core material comprises a composition of a bio-based curing agent and GO grafted with a bio-based curing agent (Ami-GO);

[0014] The described microcapsule B, whose core material comprises a composition of a bio-based epoxy resin and GO grafted with a bio-based epoxy resin (E-GO).

[0015] Among them, the poly(methyl methacrylate), Mw ~ 195000; the polysulfone, Mw ~ 80000; the polylactic acid, Mw ~ 200000.

[0016] Among them, the preparation method of the GO grafted with amino molecules (M-GO) refers to the prior art: L. Zhou, P. Zhang, L. Shen, L. Chu, J. Wu, Y. Ding, B. Zhong, X. Zhang, N. Bao, Modified graphene oxide / waterborne epoxy composite coating with enhanced corrosion resistance, Prog Org Coat 172 (2022) 107100.

[0017] Among them, the preparation of the GO grafted with a bio-based curing agent (Ami-GO) can be carried out according to the following method:

[0018] (i) Ultrasonically exfoliate the GO / DMF solution with a concentration of 1 g / L at 80 kHz;

[0019] (ii) Mix the bio-based curing agent, N,N'-dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP) and the GO / DMF solution obtained in step (i), and stir at 80 °C for 24 h to obtain a reaction solution after the reaction; among them, the mass molar ratio of GO to the bio-based curing agent, N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine is 50 mg: 1.5 mmol: 1.5 mmol: 1.5 mmol;

[0020] (iii) Wash the reaction solution obtained in step (ii) with ethanol 5 - 6 times to obtain Ami-GO.

[0021] Among them, the preparation method of the grafted bio-based epoxy resin GO (E-GO) refers to the prior art: Y. Zhang, L. Chu, Z. Dai, N. Bao, M. B. de Rooij, L. Gao, W. Tan, L. Shen, Synergistically enhancing the performance of cardanol-rich epoxy anticorrosive coatings using cardanol-based reactive diluent and its functionalized graphene oxide, Prog Org Coat 171 (2022) 107060.

[0022] In some embodiments, the bio-based surfactant is any one of cardanol-based surfactants, castor oil-based surfactants, and soybean oil-based surfactants; the amino molecule in the GO grafted with amino molecules is maleic diamine or p-phenylenediamine; the bio-based curing agent is any one of cardanol-based curing agents, castor oil-based curing agents, and soybean oil-based curing agents; the bio-based epoxy resin is composed of any one of cardanol-based glycidyl ether, castor oil-based glycidyl ether, and soybean oil-based glycidyl ether and epoxy resin in any proportion.

[0023] In some embodiments, preferably, the bio-based surfactant is a cardanol-based surfactant; the amino molecule in the GO grafted with amino molecules is maleic diamine; the bio-based curing agent is a cardanol-based curing agent; the bio-based epoxy resin is composed of cardanol-based glycidyl ether and epoxy resin in a mass ratio of 3:7.

[0024] In some embodiments, the mass ratio of the bio-based curing agent to the GO grafted with the bio-based curing agent in the core material is 1:0.01 - 0.03; the mass ratio of the bio-based epoxy resin to the GO grafted with the bio-based epoxy resin in the core material is 1:0.01 - 0.03; the mass ratio of the bio-based surfactant to the GO grafted with amino molecules in the outer layer of the capsule wall is 10:0.01 - 0.03; the mass ratio of the capsule wall, the core, and the outer layer of the capsule wall is 1 - 2:1.01 - 1.03:10.01 - 10.03.

[0025] In some embodiments, preferably, the mass ratio of the bio-based curing agent to GO grafted with the bio-based curing agent in the core material is 1:0.03; the mass ratio of the bio-based epoxy resin to GO grafted with the bio-based epoxy resin in the core material is 1:0.03; the mass ratio of the bio-based surfactant to GO grafted with amino molecules in the outer coating of the capsule wall is 10:0.03; the mass ratio of the capsule wall, the core and the outer coating of the capsule wall is 1:1.03:10.03.

[0026] In some embodiments, the particle size of the microcapsules is 5 - 30 microns; among them, the microcapsules with a particle size of 5 - 30 microns can achieve the best self-healing performance of the bio-based coating. The microcapsules with appropriate size and uniform particle size are dispersed in the coating, uniformly improving the mechanical properties of the coating and ensuring the stability of the release rate after the microcapsules rupture.

[0027] Furthermore, the present invention discloses a preparation method of the above-mentioned graphene oxide modified bio-based microcapsules, which comprises the following steps:

[0028] (1) Using water as a solvent, adding a bio-based surfactant, and stirring until the solid materials are completely dissolved to obtain an aqueous solution of the emulsifier.

[0029] (2) Dissolving the bio-based curing agent and the material of the capsule wall in dichloromethane, and then adding GO grafted with the bio-based curing agent, followed by ultrasonic dispersion to obtain an oil phase; alternatively, dissolving the bio-based epoxy resin and the material of the capsule wall in dichloromethane, and then adding GO grafted with the bio-based epoxy resin, followed by ultrasonic dispersion to obtain an oil phase.

[0030] (3) Adding GO grafted with amino molecules to a part of the aqueous solution of the emulsifier obtained in step (1), and performing ultrasonic dispersion to obtain an aqueous phase.

[0031] (4) Adding the oil phase obtained in step (2) to the aqueous phase obtained in step (3), stirring and mixing uniformly to form an emulsion.

[0032] (5) Adding the emulsion obtained in step (4) to the remaining aqueous solution of the emulsifier obtained in step (1), stirring and reacting, and after the reaction is completed, post-treating the reaction solution to obtain the graphene oxide modified bio-based microcapsules.

[0033] In some embodiments, in step (1), the mass ratio of the bio-based surfactant to water is 1 - 5:100; the mass ratio of the bio-based surfactant to GO grafted with amino molecules is 10:0.01 - 0.03.

[0034] In some embodiments, preferably, in step (1), the mass ratio of the bio-based surfactant to water is 5:100; the mass ratio of the bio-based surfactant to GO grafted with amino molecules is 10:0.03.

[0035] In some embodiments, the GO of the grafted bio-based curing agent exists in the form of a mixed solution. The solvent in the mixed solution is ethanol, and the concentration of the GO of the grafted bio-based curing agent in the mixed solution is 5-10 g / L; the GO of the grafted bio-based epoxy resin exists in the form of a mixed solution. The solvent in the mixed solution is ethanol, and the concentration of the GO of the grafted bio-based epoxy resin in the mixed solution is 5-10 g / L; the GO of the grafted amino molecule exists in the form of a mixed solution. The solvent in the mixed solution is water, and the concentration of the GO of the grafted amino molecule in the mixed solution is 5-10 g / L; for the ultrasonic dispersion, the ultrasonic temperature is room temperature, and the ultrasonic frequency is 30-80 kHz.

[0036] In some embodiments, preferably, the GO of the grafted bio-based curing agent exists in the form of a mixed solution. The solvent in the mixed solution is ethanol, and the concentration of the GO of the grafted bio-based curing agent in the mixed solution is 10 g / L; the GO of the grafted bio-based epoxy resin exists in the form of a mixed solution. The solvent in the mixed solution is ethanol, and the concentration of the GO of the grafted bio-based epoxy resin in the mixed solution is 10 g / L; the GO of the grafted amino molecule exists in the form of a mixed solution. The solvent in the mixed solution is water, and the concentration of the GO of the grafted amino molecule in the mixed solution is 10 g / L; for the ultrasonic dispersion, the ultrasonic temperature is room temperature, and the ultrasonic frequency is 80 kHz.

[0037] In some embodiments, in step (2), the mass ratio of the bio-based curing agent to the capsule wall material is 1:1-2; the mass-volume ratio of the bio-based curing agent to dichloromethane is 1 g: 30 mL-50 mL; the mass ratio of the bio-based curing agent to the GO of the grafted bio-based curing agent is 1:0.01-0.03; the mass ratio of the bio-based epoxy resin to the capsule wall material is 1:1-2; the mass-volume ratio of the bio-based epoxy resin to dichloromethane is 1 g: 30 mL-50 mL; the mass ratio of the bio-based epoxy resin to the GO of the grafted bio-based epoxy resin is 1:0.01-0.03.

[0038] In some embodiments, preferably, in step (2), the mass ratio of the bio-based curing agent to the capsule wall material is 1:1; the mass-volume ratio of the bio-based curing agent to dichloromethane is 1 g: 30 mL; the mass ratio of the bio-based curing agent to the GO of the grafted bio-based curing agent is 1:0.03; the mass ratio of the bio-based epoxy resin to the capsule wall material is 1:1; the mass-volume ratio of the bio-based epoxy resin to dichloromethane is 1 g: 30 mL; the mass ratio of the bio-based epoxy resin to the GO of the grafted bio-based epoxy resin is 1:0.03.

[0039] In some embodiments, in step (3), for the aqueous emulsifier solution obtained in part of step (1), its usage amount is calculated according to the following ratio: the mass-volume ratio of the GO grafted with amino molecules to the aqueous emulsifier solution is 0.01 g to 0.03 g: 80 mL, preferably 0.03 g: 80 mL.

[0040] In some embodiments, in step (4), the mass ratio of the wall material in the oil phase to the GO grafted with amino molecules in the water phase is 1 to 2: 0.01 to 0.03; for the stirring and mixing, the stirring rate is 1000 to 2000 r / min, and the stirring time is 10 to 15 min.

[0041] In some embodiments, preferably, in step (4), the mass ratio of the wall material in the oil phase to the GO grafted with amino molecules in the water phase is 1: 0.03; for the stirring and mixing, the stirring rate is 1000 r / min, and the stirring time is 15 min.

[0042] In some embodiments, in step (5), for the stirring reaction, the stirring temperature is 30 to 50 °C, the stirring time is 3 to 5 h, and the stirring rate is 300 to 500 r / min.

[0043] In some embodiments, preferably, in step (5), for the stirring reaction, the stirring temperature is 40 °C, the stirring time is 4 h, and the stirring rate is 300 r / min.

[0044] The application of the above-mentioned graphene oxide modified bio-based microcapsules in the preparation of self-healing bio-based coatings is also within the protection scope of the present invention.

[0045] In some embodiments, the above-mentioned application is specifically: stirring and dispersing and mixing the microcapsule A, microcapsule B with the bio-based coating, and then the self-healing bio-based coating can be obtained.

[0046] In some embodiments, the bio-based coating is a cardanol coating, a castor oil coating or a soybean oil epoxy resin coating; the total mass of microcapsule A and microcapsule B in the self-healing bio-based coating is 5 to 20 wt%; the mass ratio of microcapsule A to microcapsule B is 1 to 2: 1.

[0047] In some embodiments, preferably, the bio-based coating is a cardanol coating; the total mass of microcapsule A and microcapsule B in the self-healing bio-based coating is 20 wt%; the mass ratio of microcapsule A to microcapsule B is 1: 1.

[0048] Among them, the material of the above-mentioned capsule core is a bio-based healing agent that can repair the self-healing bio-based coating and modified GO grafted with the bio-based healing agent, which is encapsulated in the capsule wall material; when microcracks appear in the self-healing bio-based coating, the capsule wall of the microcapsule ruptures, releasing the capsule core material to heal the crack area. The modified GO material contained in the capsule core is dispersed at the healing site to achieve the self-healing of the coating.

[0049] Among them, the bio-based coating is a coating layer formed by coating a bio-based paint on the surface of a metal substrate.

[0050] Among them, the above-mentioned bio-based microcapsules modified with graphene oxide are applied to the bio-based paint to obtain a self-healing bio-based coating with high corrosion resistance and self-healing ability.

[0051] Among them, preferably, the microcapsules can be added to the bio-based paint by means of stirring and dispersion. The bio-based paint added with the microcapsules is coated on the metal substrate to obtain a self-healing bio-based coating. When microcracks appear on the surface of the self-healing bio-based coating under the action of external force, the microcapsules rupture under the action of stress expansion, releasing the encapsulated healing agent and modified GO to repair the crack area and improve the corrosion resistance and mechanical properties of the bio-based coating.

[0052] Beneficial effects:

[0053] (1) The microcapsules prepared by the present invention encapsulate two kinds of repair agents and modified GO grafted with the corresponding repair agents. One is a bio-based curing agent, and the other is a bio-based epoxy resin. The two repair agents are released and cured after the microcapsules are broken to repair the crack site. At the same time, the released modified GO can enhance the barrier and mechanical properties of the healing area.

[0054] (2) The present invention modifies GO by grafting amino groups to enhance the mutual binding force between the microcapsules and the coating matrix, which helps to improve the dispersibility and healing efficiency of the microcapsules (the presence of GO when microcracks appear can cause the microcapsules to rupture quickly, thereby releasing the healing factor).

[0055] (3) The modified GO grafted with amino groups of the present invention is wrapped on the surface of the bio-based microcapsules, which can effectively hinder the penetration of corrosion factors and improve the corrosion resistance of the coating. The prepared microcapsules can improve the intrinsic barrier performance of the bio-based coating while endowing the coating with self-healing performance.

[0056] (4) The bio-based surfactant used in the present invention can improve the preparation efficiency and morphology of the bio-based microcapsules. At the same time, reference can also be made to Patent CN115322613B.

[0057] (5) The bio-based healing agent in a single microcapsule cannot react alone and has no healing effect after release. Therefore, microcapsule A and microcapsule B need to be mixed evenly and used simultaneously in the coating. When cracks appear in the coating, microcapsules A and B are broken simultaneously, releasing the encapsulated bio-based curing agent and bio-based resin inside to react and heal the cracked area. Description of the Drawings

[0058] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0059] Figure 1 Infrared spectrum of Ami-GO prepared in Example 1.

[0060] Figure 2 SEM photograph of GO-modified cardanol curing agent microcapsules prepared in Example 1.

[0061] Figure 3 Particle size distribution of GO-modified cardanol curing agent microcapsules prepared in Example 1.

[0062] Figure 4 SEM photograph of GO-modified cardanol epoxy resin microcapsules prepared in Example 1.

[0063] Figure 5 Particle size distribution of GO-modified cardanol epoxy resin microcapsules prepared in Example 1.

[0064] Figure 6 Comparison photos of the "X" scratch on the bio-based coating before and after adding the two microcapsules in Example 1.

[0065] Figure 7 Bode diagram of electrochemical impedance of the bio-based coating added with the two microcapsules in Example 1.

[0066] Figure 8 SEM photograph of cardanol curing agent microcapsules prepared in Comparative Example 1.

[0067] Figure 9 Particle size distribution of cardanol curing agent microcapsules prepared in Comparative Example 1.

[0068] Figure 10 SEM photograph of cardanol epoxy resin microcapsules prepared in Comparative Example 1.

[0069] Figure 11 Particle size distribution of cardanol epoxy resin microcapsules prepared in Comparative Example 1.

[0070] Figure 12Electrochemical impedance Bode plots of the bio-based coatings incorporating the cardanol curing agent microcapsules and cardanol resin microcapsules prepared in Comparative Example 1.

[0071] Figure 13 Electrochemical impedance Bode plots of the bio-based coatings incorporating the cardanol curing agent microcapsules and cardanol epoxy resin microcapsules prepared in Comparative Example 2. Detailed implementation manners

[0072] The present invention can be better understood according to the following examples.

[0073] The polymethyl methacrylate used in the examples of the present invention has Mw ~ 195000.

[0074] Example 1

[0075] Preparation of modified GO:

[0076] Preparation method of GO grafted with amino molecules (M-GO): The preparation method can refer to the work of Pengbo Zhang et al., L. Zhou, P. Zhang, L. Shen, L. Chu, J. Wu, Y. Ding, B. Zhong, X. Zhang, N. Bao, Modified graphene oxide / waterborne epoxy composite coating with enhanced corrosion resistance, Prog Org Coat 172 (2022) 107100. Among them, the amino molecule in the GO grafted with amino molecules is maleic diamine, and GO grafted with maleic diamine, namely M-GO, was synthesized.

[0077] Preparation method of GO grafted with bio-based epoxy resin (E-GO): The preparation method can refer to the work of Yingying Zhang et al., Y. Zhang, L. Chu, Z. Dai, N. Bao, M. B. de Rooij, L. Gao, W. Tan, L. Shen, Synergistically enhancing the performance of cardanol-rich epoxy anticorrosive coatings using cardanol-based reactive diluent and its functionalized graphene oxide, Prog Org Coat 171 (2022) 107060. GO grafted with cardanol-based epoxy resin, namely E-GO, was synthesized.

[0078] Preparation method of GO grafted with bio-based curing agent (Ami-GO):

[0079] (i) Ultrasonically exfoliate a GO / DMF solution with a concentration of 1 g / L in a flask at 80 kHz.

[0080] (ii) Mix the cardanol-based curing agent (PLR718A), N,N'-dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), and the GO / DMF solution obtained in step (i), and stir at 80 °C for 24 h to obtain a reaction solution after the reaction; among them, the dosage ratio of GO:PLR718A:DCC:DMAP is 50 mg:1.5 mmol:1.5 mmol:1.5 mmol.

[0081] (iii) Wash the reaction solution obtained in step (ii) with ethanol 5 - 6 times to obtain Ami-GO.

[0082] The infrared spectrum of Ami-GO is as Figure 1 shown, and the infrared spectrum of Ami-GO shows that GO is successfully grafted with the cardanol-based curing agent 718A.

[0083] Preparation of GO-modified cardanol curing agent microcapsules:

[0084] (1) Take 10 g of cardanol surfactant (NSF3007C) and add it to 200 g of deionized water, and stir at room temperature until the solid material is completely dissolved to obtain an aqueous solution containing 5 wt% cardanol surfactant.

[0085] (2) Add 1 g of cardanol curing agent (PLR718A) and 1 g of polymethyl methacrylate in a mass ratio of 1:1 to 30 mL of dichloromethane, and stir until completely dissolved; then add 3 mL of an ethanol mixture containing Ami-GO (the concentration of Ami-GO in the mixture is 10 g / L), and ultrasonically disperse the solid material at 80 kHz for 15 min at room temperature to obtain an oil phase.

[0086] (3) Add 3 mL of an aqueous mixture containing M-GO (the concentration of M-GO in the mixture is 10 g / L) to 80 mL of an aqueous solution containing 5 wt% cardanol surfactant (prepared in step (1)), and ultrasonically disperse the solid material at 80 kHz for 15 min at room temperature to obtain an aqueous phase.

[0087] (4) Slowly add the oil phase containing Ami-GO obtained in step (2) to the aqueous phase obtained in step (3), and mechanically stir at 1000 rpm for 15 min to form an emulsion.

[0088] (5) Pour the emulsion obtained in step (4) into 120 mL of an aqueous solution containing 5 wt% cardanol surfactant (prepared in step (1)), and stir it at 300 rpm for 4 h with an open mouth at 40 °C to completely volatilize dichloromethane, obtaining a suspension of polymethyl methacrylate-coated cardanol curing agent microcapsules. After centrifugation, washing, and vacuum drying, GO-modified cardanol curing agent microcapsules can be obtained.

[0089] As Figure 2 shown, the GO-modified cardanol curing agent microcapsules are in regular spherical shapes, and there are modified GO sheets inserted and wrapped on the outer surface of the microcapsules.

[0090] As Figure 3 shown, the average particle size of the GO-modified cardanol curing agent microcapsules is about 14 μm.

[0091] Preparation of GO-modified cardanol epoxy resin microcapsules:

[0092] (1) Take 10 g of cardanol surfactant (NSF3007C) and add it to 200 g of deionized water, and stir at room temperature until the solid material is completely dissolved, obtaining an aqueous solution containing 5 wt% cardanol surfactant.

[0093] (2) Mix 0.3 g of cardanol-based glycidyl ether (PLR602A) and 0.7 g of epoxy resin (E51) to obtain a mixture; add 1 g of the mixture and 1 g of polymethyl methacrylate to 30 mL of dichloromethane according to a mass ratio of 1:1, and stir until completely dissolved; then add 3 mL of an ethanol mixture containing E-GO (the concentration of E-GO in the mixture is 10 g / L), and ultrasonicate at 80 kHz for 15 min at room temperature until the solid material is completely dispersed, obtaining an oil phase.

[0094] (3) Add 3 mL of an aqueous mixture containing M-GO (the concentration of M-GO in the mixture is 10 g / L) to 80 mL of an aqueous solution containing 5 wt% cardanol surfactant (prepared in step (1)), and ultrasonicate at 80 kHz for 15 min at room temperature until the solid material is completely dispersed, obtaining an aqueous phase.

[0095] (4) Slowly drop the oil phase containing E-GO obtained in step (2) into the aqueous phase obtained in step (3), and mechanically stir at a speed of 1000 rpm for 15 min to form an emulsion.

[0096] (5) Pour the emulsion obtained in step (4) into 120 mL of an aqueous solution containing 5 wt% cardanol surfactant (prepared in step (1)), stir it at 300 rpm for 4 h with an open mouth at 40 °C to completely volatilize dichloromethane, and obtain a suspension of polymethyl methacrylate-coated cardanol epoxy resin microcapsules. After centrifugation, washing, and vacuum drying, GO-modified cardanol epoxy resin microcapsules can be obtained.

[0097] As Figure 4 shown, the GO-modified cardanol epoxy resin microcapsules are regular spheres, and some modified GO sheets are wrapped on the outer surface of the microcapsules.

[0098] As Figure 5 shown, the average particle size of the GO-modified cardanol epoxy resin microcapsules is about 12 μm.

[0099] Preparation of self-healing bio-based coating:

[0100] The substrate material is a steel plate. Polish the surface of the steel plate smooth with 800-mesh sandpaper, clean the surface with ethanol, and air-dry it naturally. Add the GO-modified cardanol curing agent microcapsules and GO-modified cardanol epoxy resin microcapsules prepared above to the cardanol coating at 10 wt% respectively (the dosage ratio of GO-modified cardanol curing agent and cardanol epoxy resin microcapsules is 1:1, and the addition amount of both is 10 wt%), stir evenly, and then scrape the coating on the surface of the steel plate and cure it at room temperature for 24 h to obtain a self-healing coating.

[0101] As Figure 6 shown, when "X" scratches are made on the surface of the bio-based coating containing 10 wt% GO-modified cardanol curing agent microcapsules and 10 wt% GO-modified cardanol epoxy resin microcapsules, after self-healing at room temperature for 24 h, the scratches almost completely disappear.

[0102] As Figure 7 shown, when the bio-based coating containing 10 wt% GO-modified cardanol curing agent microcapsules and 10 wt% GO-modified cardanol epoxy resin microcapsules is immersed in 3.5 wt% NaCl solution for 30 days, the Bode diagram shows that the low-frequency impedance value drops to around 5.51×10 9 Ω·cm -1 , indicating that the brine has entered the coating but has not yet contacted the substrate. Compared with the unmodified microcapsules in Comparative Example 1 and Comparative Example 2, the low-frequency impedance value of the coating is greatly improved, and the anti-corrosion ability is greatly enhanced.

[0103] Comparative Example 1: Do not add modified GO

[0104] Preparation of cardanol curing agent microcapsules:

[0105] (1) Take 10 g of cardanol surfactant (NSF3007C) and add it to 200 g of deionized water. Stir at room temperature until the solid material is completely dissolved to obtain an aqueous solution containing 5 wt% cardanol surfactant;

[0106] (2) Add 1 g of cardanol curing agent (PLR718A) and 1 g of polymethyl methacrylate in a mass ratio of 1:1 to 30 mL of dichloromethane, and stir until completely dissolved to obtain an oil phase;

[0107] (3) Slowly add the oil phase obtained in step (2) to 80 mL of the aqueous solution containing 5 wt% cardanol surfactant (prepared in step (1)), and mechanically stir at 1000 rpm for 15 min to form an emulsion;

[0108] (4) Pour the emulsion obtained in step (3) into 120 mL of the aqueous solution containing 5 wt% cardanol surfactant (prepared in step (1)), and stir at 300 rpm with an open mouth at 40 °C for 4 h to completely volatilize dichloromethane, obtaining a suspension of polymethyl methacrylate-coated cardanol curing agent microcapsules. After centrifugation, washing, and vacuum drying, cardanol curing agent microcapsules can be obtained.

[0109] As Figure 8 shown, the cardanol curing agent microcapsules are regular spheres with a smooth surface, no holes, and no depressions.

[0110] As Figure 9 shown, the average particle size of the cardanol curing agent microcapsules is about 9.8 μm.

[0111] Preparation of cardanol epoxy resin microcapsules:

[0112] (1) Take 10 g of cardanol surfactant (NSF3007C) and add it to 200 g of deionized water. Stir at room temperature until the solid material is completely dissolved to obtain an aqueous solution containing 5 wt% cardanol surfactant;

[0113] (2) Mix 0.3 g of cardanol diluent (PLR602A) and 0.7 g of epoxy resin (E51) to obtain a mixture; add 1 g of the mixture and 1 g of polymethyl methacrylate in a mass ratio of 1:1 to 30 mL of dichloromethane, and stir until completely dissolved to obtain an oil phase;

[0114] (3) Slowly add the oil phase obtained in step (2) to 80 mL of the aqueous solution containing 5 wt% anionic cardanol surfactant (prepared in step (1)), and mechanically stir at 1000 rpm for 15 min to form an emulsion;

[0115] (4) Pour the emulsion obtained in step (3) into 120 mL of an aqueous solution containing 5 wt% cardanol surfactant (prepared in step (1)), and stir it at 300 rpm for 4 h with an open mouth at 40 °C to completely volatilize dichloromethane, obtaining a suspension of polymethyl methacrylate-coated cardanol epoxy resin microcapsules. After centrifugation, washing, and vacuum drying, cardanol epoxy resin microcapsules can be obtained.

[0116] As Figure 10 shown, the cardanol epoxy resin microcapsules are regular spheres with a smooth surface, no holes, and no depressions.

[0117] As Figure 11 shown, the average particle size of the cardanol epoxy resin microcapsules is about 8.9 μm.

[0118] Preparation of self-healing bio-based coating:

[0119] The substrate material is a steel plate. The surface of the steel plate is polished smooth with 800-mesh sandpaper, and the surface is cleaned with ethanol and then air-dried naturally. The obtained cardanol curing agent microcapsules and cardanol epoxy resin microcapsules prepared above are respectively added to the cardanol-based coating at 10 wt% (the dosage ratio of cardanol curing agent and cardanol epoxy resin microcapsules is 1:1, and the addition amount of both is 10 wt%). Stir evenly, and then scrape the coating on the surface of the steel plate and cure it at room temperature for 24 h to obtain a self-healing coating.

[0120] As Figure 12 shown, for the bio-based coating added with 10 wt% cardanol curing agent using NSF3007C as an emulsifier (without adding modified GO) and 10 wt% GO cardanol epoxy resin microcapsules (without adding modified GO), after soaking in 3.5 wt% NaCl solution for 30 days, the Bode diagram shows that the resistance drops to around 1.1×10 7 Ω·cm-1, indicating that the brine has entered the coating, but the anti-corrosion performance has a certain improvement compared with the microcapsules using petroleum-based surfactant as an emulsifier in Comparative Example 2.

[0121] Comparative Example 2: Without adding modified GO, using petroleum-based surfactant as an emulsifier

[0122] Preparation of cardanol curing agent microcapsules:

[0123] (1) Take 10 g of petroleum-based surfactant (PVA) and add it to 200 g of deionized water, and stir at room temperature until the solid material is completely dissolved to obtain an aqueous solution containing 5 wt% PVA;

[0124] (2) Add 1 g of cardanol curing agent (PLR718A) and 1 g of polymethyl methacrylate to 30 mL of dichloromethane according to a mass ratio of 1:1, and stir until completely dissolved to obtain an oil phase;

[0125] (3) Slowly add the oil phase obtained in step (2) to 80 mL of an aqueous solution containing 5 wt% PVA (prepared in step (1)), and mechanically stir at 1000 rpm for 15 min to form an emulsion.

[0126] (4) Pour the emulsion obtained in step (3) into 120 mL of an aqueous solution containing 5 wt% PVA (prepared in step (1)), and stir it at 300 rpm with an open mouth at 40 °C for 4 h to completely volatilize dichloromethane, obtaining a suspension of microcapsules of polymethyl methacrylate-coated cardanol curing agent. After centrifugation, washing, and vacuum drying, the cardanol curing agent microcapsules can be obtained, with an average particle size of about 10.5 μm.

[0127] Preparation of cardanol epoxy resin microcapsules:

[0128] (1) Take 10 g of petroleum-based surfactant (PVA) and add it to 200 g of deionized water, and stir at room temperature until the solid material is completely dissolved to obtain an aqueous solution containing 5 wt% PVA.

[0129] (2) Mix 0.3 g of cardanol diluent (PLR602A) and 0.7 g of epoxy resin (E51) to obtain a mixture; add 1 g of the mixture and 1 g of polymethyl methacrylate to 30 mL of dichloromethane according to a mass ratio of 1:1, and stir until completely dissolved to obtain an oil phase.

[0130] (3) Slowly add the oil phase obtained in step (2) to 80 mL of an aqueous solution containing 5 wt% PVA (prepared in step (1)), and mechanically stir at 1000 rpm for 15 min to form an emulsion.

[0131] (4) Pour the emulsion obtained in step (3) into 120 mL of an aqueous solution containing 5 wt% PVA (prepared in step (1)), and stir it at 300 rpm with an open mouth at 40 °C for 4 h to completely volatilize dichloromethane, obtaining a suspension of microcapsules of polymethyl methacrylate-coated cardanol epoxy resin. After centrifugation, washing, and vacuum drying, the cardanol epoxy resin microcapsules can be obtained, with an average particle size of about 11 μm.

[0132] Preparation of self-healing bio-based coating:

[0133] The substrate material is a steel plate. Polish the surface of the steel plate smooth with 800-mesh sandpaper, and clean the surface with ethanol and air-dry it naturally. Add the prepared cardanol curing agent microcapsules and cardanol epoxy resin microcapsules to the cardanol-based coating at 10 wt% respectively (the doping amount of the curing agent and resin microcapsules is 1:1, and the addition amount of both is 10 wt%), stir evenly, and then scrape the coating on the surface of the steel plate and cure it at room temperature for 24 h to obtain a self-healing coating.

[0134] As Figure 13 shown, after soaking the bio-based coating added with 10 wt% of cardanol curing agent microcapsules with PVA as an emulsifier and 10 wt% of cardanol epoxy resin microcapsules with PVA as an emulsifier in a 3.5 wt% NaCl solution for 30 days, the Bode plot shows that the resistance value has dropped to 5.2×10 6 Ω·cm -1 or so, indicating that the brine has entered the coating, and the coating has been broken down by the corrosive medium and lost its anti-corrosion ability.

[0135] Comparative Example 3: Adding unmodified GO

[0136] An attempt was made to prepare bio-based curing agent microcapsules / bio-based epoxy resin microcapsules by adding unmodified graphene oxide. Due to the negative charge on the surface of unmodified GO, it is difficult to effectively encapsulate the surface of the microcapsules with the same surface electronegativity (due to the presence of surfactants). Therefore, the microcapsules encapsulated with unmodified GO were not successfully prepared.

[0137] The present invention provides an idea and method for preparing and applying graphene oxide-modified bio-based microcapsules. There are many specific methods and ways to implement this technical solution. The above description is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by existing technologies.

Claims

1. A graphene oxide modified bio-based microcapsule, characterized in that, The bio-based microcapsules are microcapsule A and / or microcapsule B; both microcapsule A and microcapsule B include a capsule wall, a capsule core, and an outer coating of the capsule wall; the capsule wall materials of microcapsule A and microcapsule B are the same, the outer coating materials of the capsule walls of microcapsule A and microcapsule B are the same, and the capsule core materials of microcapsule A and microcapsule B are different; The capsule wall, its material includes polymethyl methacrylate, polysulfone or polylactic acid; The outer coating of the capsule wall, its material includes a bio-based surfactant and GO grafted with amino molecules; Microcapsule A, its capsule core material includes a composition of a bio-based curing agent and GO grafted with the bio-based curing agent; Microcapsule B, its capsule core material includes a composition of a bio-based epoxy resin and GO grafted with cardanol-based glycidyl ether; The bio-based surfactant is a cardanol-based surfactant; The amino molecule in the GO grafted with amino molecules is maleic diamine; The bio-based curing agent is a cardanol-based curing agent; The bio-based epoxy resin is prepared by mixing cardanol-based glycidyl ether and epoxy resin in any proportion; 2. The bio-based microcapsule according to claim 1, characterized in that, In the capsule core material, the mass ratio of the bio-based curing agent to the GO grafted with the bio-based curing agent is 1:0.01 - 0.03; in the capsule core material, the mass ratio of the bio-based epoxy resin to the GO grafted with cardanol-based glycidyl ether is 1:0.01 - 0.03; in the outer coating of the capsule wall, the mass ratio of the bio-based surfactant to the GO grafted with amino molecules is 10:0.01 - 0.03; the mass ratio of the capsule wall, the capsule core and the outer coating of the capsule wall is 1 - 2:1.01 - 1.03:10.01 - 10.03; the particle size of the microcapsules is 5 - 30 microns.

3. The preparation method of the bio-based microcapsule according to any one of claims 1 to 2, characterized in that, It includes the following steps: (1) Using water as a solvent, adding a bio-based surfactant, and stirring until the solid materials are completely dissolved to obtain an aqueous surfactant solution; (2) Dissolving the bio-based curing agent and the material of the capsule wall in dichloromethane, and then adding GO grafted with the bio-based curing agent, and ultrasonically dispersing to obtain an oil phase; or, dissolving the bio-based epoxy resin and the material of the capsule wall in dichloromethane, and then adding GO grafted with cardanol-based glycidyl ether, and ultrasonically dispersing to obtain an oil phase; (3) Adding GO grafted with amino molecules to a part of the aqueous surfactant solution obtained in step (1), and ultrasonically dispersing to obtain an aqueous phase; (4) Adding the oil phase obtained in step (2) to the aqueous phase obtained in step (3), and stirring and mixing evenly to form an emulsion; (5) Adding the emulsion obtained in step (4) to the remaining aqueous surfactant solution obtained in step (1), stirring and reacting, and after the reaction is completed, post-treating the reaction solution to obtain the graphene oxide-modified bio-based microcapsules.

4. The preparation method according to claim 3, wherein In step (1), the mass ratio of the bio-based surfactant to water is 1 - 5:100; the mass ratio of the bio-based surfactant to the GO grafted with amino molecules is 10:0.01 - 0.

03.

5. The preparation method according to claim 3, characterized in that, The GO of the grafted bio-based curing agent exists in the form of a mixed solution. The solvent in the mixed solution is ethanol, and the concentration of GO of the grafted bio-based curing agent in the mixed solution is 5-10 g / L; the GO of the grafted cardanol-based glycidyl ether exists in the form of a mixed solution. The solvent in the mixed solution is ethanol, and the concentration of GO of the grafted cardanol-based glycidyl ether in the mixed solution is 5-10 g / L; the GO of the grafted amino molecule exists in the form of a mixed solution. The solvent in the mixed solution is water, and the concentration of GO of the grafted amino molecule in the mixed solution is 5-10 g / L; for the ultrasonic dispersion, the ultrasonic temperature is room temperature, and the ultrasonic frequency is 30-80 kHz.

6. The preparation method according to claim 3, wherein In step (2), the mass ratio of the bio-based curing agent to the wall material is 1:1-2; the mass-volume ratio of the bio-based curing agent to dichloromethane is 1 g: 30 mL-50 mL; the mass ratio of the bio-based curing agent to the GO of the grafted bio-based curing agent is 1: 0.01-0.03; the mass ratio of the bio-based epoxy resin to the wall material is 1:1-2; the mass-volume ratio of the bio-based epoxy resin to dichloromethane is 1 g: 30 mL-50 mL; the mass ratio of the bio-based epoxy resin to the GO of the grafted cardanol-based glycidyl ether is 1: 0.01-0.

03.

7. The preparation method according to claim 3, characterized in that In step (3), the amount of the surfactant aqueous solution obtained in part of step (1) is calculated according to the following ratio: the mass-volume ratio of the GO of the grafted amino molecule to the surfactant aqueous solution is 0.01 g-0.03 g: 80 mL.

8. The preparation method according to claim 3, characterized in that, In step (4), the mass ratio of the wall material in the oil phase to the GO of the grafted amino molecule in the water phase is 1-2: 0.01-0.03; for the stirring and mixing, the stirring rate is 1000-2000 r / min, and the stirring time is 10-15 min.

9. The preparation method according to claim 3, wherein In step (5), for the stirring reaction, the stirring temperature is 30-50 °C, the stirring time is 3-5 h, and the stirring rate is 300-500 r / min.

10. Use of the graphene oxide modified biobased microcapsules according to any one of claims 1 to 2 in the preparation of a self-healing biobased coating, characterized in that, Stir and disperse and mix the microcapsule A, microcapsule B and the bio-based coating to obtain a self-healing bio-based coating; wherein, the bio-based coating is a cardanol coating, a castor oil coating or a soybean oil epoxy resin coating; the total mass of microcapsule A and microcapsule B in the self-healing bio-based coating is 5-20 wt%; the mass ratio of microcapsule A to microcapsule B is 1-2: 1.

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