High-toughness seawater low-temperature environment self-repairing epoxy coating as well as preparation method and application thereof

Abstract

The invention discloses a high-toughness seawater low-temperature environment self-repairing epoxy coating as well as a preparation method and application thereof. The preparation method comprises the following steps: providing a modified epoxy adaptive network material; the modified epoxy adaptive network material is prepared from epoxy resin, polyol, diisocyanate and a monomer containing dynamic chemical bonds through a reaction. Providing a modified Ti < 3 > C < 2 > T < x > two-dimensional nanosheet; the modified Ti < 3 > C < 2 > T < x > two-dimensional nanosheet is obtained by modifying Ti < 3 > C < 2 > T < x >-MXene by using dopamine and a modifier containing a quadruple hydrogen bond motif; and mixing the modified epoxy adaptive network material with the modified Ti < 3 > C < 2 > T < x > two-dimensional nanosheets, and carrying out an interface ordered cross-linking reaction, so as to prepare the high-toughness seawater low-temperature environment self-repairing epoxy coating. The high-toughness seawater low-temperature environment self-repairing epoxy coating provided by the invention has multiple types of dynamic chemical bonds, has excellent properties of thermosetting resin and thermoplastic resin, and shows high toughness and self-repairing characteristics.

Description

Technical Field

[0001] The present invention belongs to the technical field of self-healing coatings, and particularly relates to a high-strength and tough self-healing epoxy coating for seawater low-temperature environment, its preparation method and application. Background Art

[0002] Epoxy resins are widely used in fields such as coatings, adhesives, and structural components due to their excellent mechanical strength, chemical corrosion resistance, and thermal properties. Currently, the development of ultra-strong and tough epoxy resins with the ability to autonomously repair local damages and defects at room temperature has become a hot topic in the field of high-end intelligent manufacturing, because this can extend the service life of materials and improve the reliability and durability of functional devices, achieving sustainable development of the environment. However, the contradiction between strength, toughness, and room-temperature self-healing ability caused by the covalent cross-linked structure of epoxy resins seriously hinders their further application in high-performance composite materials. Generally, their maximum elongation rate (ε max ) is between 1% and 10%, and the tensile toughness is lower than 5 MJ·m -3 . For decades, researchers have been working hard to improve the toughness of epoxy resins. However, developing strategies that can simultaneously improve the mechanical strength and toughness of thermosetting resins remains challenging.

[0003] The coexistence of high strength and toughness as well as a certain repair ability after damage is a characteristic that often appears in biological systems. Inspired by biological structures, researchers have carried out a large number of studies to improve performance by introducing nano-fillers or constructing covalent adaptable networks. Covalent adaptable networks are polymers cross-linked by reversible covalent bonds (including disulfide bonds, oxime-carbamate bonds, and Diels-Alder adducts, etc.). It can dynamically dissociate or reversibly cross-link under specific conditions, and has self-healing and plasticity similar to thermoplastic resins. However, in traditional covalent adaptable networks, due to the strong dynamic covalent bonds and high bond energy, it is difficult to achieve self-healing under mild conditions. In addition, the addition of nano-fillers limits the mobility of polymer molecular chains, resulting in limited self-repair performance and posing challenges to simultaneously optimizing toughness and self-repair ability.

[0004] In recent years, ultrathin two-dimensional titanium carbide (Ti 3 C 2 T x )-MXene nanosheets have attracted much attention due to their excellent mechanical properties, outstanding electrical conductivity, and tunable surface chemistry. However, Ti 3 C 2 T xIts high hardness and limited interfacial compatibility with the polymer matrix hinder its effective use in practical applications. Currently, there is still a lack of effective methods to integrate these rigid two-dimensional materials with polymer networks to fabricate self-healing materials. Therefore, developing a coating that can self-repair its mechanical properties and corrosion protection functions in various environments such as room temperature, seawater, and low temperature is an urgent problem to be solved. Summary of the Invention

[0005] The main object of the present invention is to provide a high-strength and tough self-healing epoxy coating for seawater and low-temperature environments, its preparation method and application, which successfully balance the contradiction among high mechanical strength, high toughness and self-healing ability in the self-healing coating, so that it can be applied to the field of metal surface corrosion protection in marine environments and flexible sensors.

[0006] To achieve the foregoing invention object, the technical solutions adopted by the present invention include:

[0007] The embodiment of the present invention provides a preparation method of a high-strength and tough self-healing epoxy coating for seawater and low-temperature environments, which includes:

[0008] Providing a modified epoxy adaptable network material; the modified epoxy adaptable network material contains any one or a combination of main-chain hydrogen bonds, side-chain quadruple hydrogen bonds, and disulfide bonds; the modified epoxy adaptable network material is prepared by reacting epoxy resin, polyol, diisocyanate, and monomers containing dynamic chemical bonds;

[0009] Providing modified Ti 3 C 2 T x two-dimensional nanosheets; the modified Ti 3 C 2 T x two-dimensional nanosheets are obtained by modifying Ti 3 C 2 T x -MXene with dopamine and a modifier containing a quadruple hydrogen bond motif;

[0010] And, mixing the modified epoxy adaptable network material with the modified Ti 3 C 2 T x two-dimensional nanosheets to undergo an interfacial ordered crosslinking reaction to prepare a high-strength and tough self-healing epoxy coating for seawater and low-temperature environments.

[0011] The embodiment of the present invention also provides a high-strength and tough self-healing epoxy coating for seawater and low-temperature environments prepared by the foregoing preparation method, and the high-strength and tough self-healing epoxy coating for seawater and low-temperature environments has a biomimetic inverse nacreous layer structure.

[0012] The embodiment of the present invention also provides an application of the aforementioned high-strength and tough seawater low-temperature environment self-healing epoxy coating in the fields of metal surface coating self-healing-corrosion protection or flexible sensors in seawater low-temperature environments.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] (1) In the self-healing epoxy coating provided by the present invention, through the interfacial ordered crosslinking strategy, the modified epoxy adaptation network and modified Ti 3 C 2 T x There is a high-density quadruple hydrogen bond crosslinking at the interface between two-dimensional nanosheets, and then under evaporation-induced assembly, the modified two-dimensional nanosheets are arranged in a parallel manner in the epoxy coating, thereby improving the mechanical strength and toughness of the coating; its tensile strength is 20-35 MPa, and the toughness is 90-220 MJ·m -3 ;

[0015] (2) Due to the hydrophobic protection of the epoxy covalent network on various types of dynamic chemical bonds, the high-strength and tough seawater low-temperature environment self-healing epoxy coating provided by the present invention has rapid self-healing ability at room temperature, low temperature (~0 °C) and seawater environment (3.5 wt.% sodium chloride);

[0016] (3) After the high-strength and tough seawater low-temperature environment self-healing epoxy coating provided by the present invention is cut into two sections and contacted at room temperature for 0.5-12 h, its tensile strength can be restored by 80-92%, and when contacted at 0 °C for 0.5-12 h, its tensile strength can be restored by 60-84%. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is the synthesis route diagram of the modified epoxy adaptation network obtained in Example 1 of the present invention;

[0019] Figure 2 It is the scanning electron microscope image of the high-strength and tough seawater low-temperature environment self-healing epoxy coating containing parallel arranged modified Ti 3 C 2 T x nanosheets in Example 1 of the present invention;

[0020] Figure 3It is the stress-strain curve diagram of the tensile test of the high-strength and tough seawater low-temperature environment self-healing epoxy coating prepared in Example 1 of the present invention;

[0021] Figure 4 It is the scanning electron microscope image of the high-strength and tough seawater low-temperature environment self-healing epoxy coating prepared in Example 1 of the present invention after being cut into two sections and contacting at room temperature for different times;

[0022] Figure 5 It is the stress-strain curve diagram of the tensile test of the high-strength and tough seawater low-temperature environment self-healing epoxy coating prepared in Example 1 of the present invention after being cut into two sections and contacting at room temperature and 0 °C for 2 h respectively;

[0023] Figure 6a - Figure 6b It is the local electrochemical impedance diagram of the self-healing behavior of the high-strength and tough seawater low-temperature environment self-healing epoxy coating prepared in Example 1 of the present invention in a simulated seawater low-temperature environment (~0 °C);

[0024] Figure 7 It is the diagram of the resistance change of the sensor assembled with the high-strength and tough seawater low-temperature environment self-healing epoxy coating prepared in Example 1 of the present invention at different bending angles in the air / water environment. Detailed implementation manners

[0025] In view of the defects of the prior art, the inventors of this case have proposed the technical solution of the present invention through long-term research and a large number of practices. The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] Specifically, as an aspect of the technical solution of the present invention, a preparation method of a high-strength and tough seawater low-temperature environment self-healing epoxy coating includes:

[0027] Providing a modified epoxy adaptable network material; wherein, the modified epoxy adaptable network material contains any one or a combination of main-chain hydrogen bonds, side-chain quadruple hydrogen bonds, and disulfide bonds; the modified epoxy adaptable network material is prepared by reacting epoxy resin, polyol, diisocyanate, and a monomer containing a dynamic chemical bond;

[0028] Providing modified Ti 3 C 2 T x Two-dimensional nanosheets; wherein, the modified Ti 3 C 2 T x Two-dimensional nanosheets are modified Ti 3C 2 T x -obtained from MXene;

[0029] And, mixing the modified epoxy adaptable network material with modified Ti 3 C 2 T x two-dimensional nanosheets to carry out an interfacial ordered crosslinking reaction, and obtaining a high-strength and tough seawater low-temperature environment self-healing epoxy coating.

[0030] In some preferred embodiments, the preparation method of the modified epoxy adaptable network material specifically includes: blending a polyol, a diisocyanate, an organic solvent and a monomer containing a dynamic chemical bond, and stirring at 50-120 °C for 1-6 h to obtain a prepolymer; adding a monomer containing an epoxy group to the prepolymer and stirring at 70-90 °C for 2-4 h to obtain an epoxy prepolymer; finally, adding a polyetheramine curing agent to the epoxy prepolymer to obtain the modified epoxy adaptable network material.

[0031] In some preferred embodiments, the preparation method specifically includes:

[0032] Mixing a polyol, a diisocyanate, a monomer containing a dynamic chemical bond, and an organic solvent and stirring at 50-120 °C for 1-6 h to obtain a prepolymer;

[0033] Adding a monomer containing an epoxy group to the prepolymer and stirring at 70-90 °C for 2-4 h to obtain an epoxy prepolymer;

[0034] And, adding a polyetheramine curing agent to the epoxy prepolymer to obtain the modified epoxy adaptable network material.

[0035] Further, the polyol includes polytetrahydrofuran and / or polypropylene glycol, and is not limited thereto.

[0036] Furthermore, the polytetrahydrofuran has different molecular weights, for example: PTMEG-250, PTMEG-650, PTMEG-1000, PTMEG-2000, PTMEG-3000.

[0037] Furthermore, the polypropylene glycol has different molecular weights, for example: PPG-400, PPG-1000, PPG-2000.

[0038] Further, the diisocyanate includes an alicyclic diisocyanate and / or an aliphatic diisocyanate; the alicyclic diisocyanate includes any one or a combination of isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate (HMDI), toluene-2,5-diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI); the aliphatic diisocyanate includes hexamethylene diisocyanate (HDI) and / or L-lysine diisocyanate (LDI), and is not limited thereto.

[0039] Further, the monomer containing a dynamic chemical bond includes a monomer containing a side-chain quadruple hydrogen bond motif and / or a monomer containing a disulfide bond; the monomer containing a side-chain quadruple hydrogen bond motif includes a ureido-4-pyridone (UPy) chain extender; the monomer containing a disulfide bond includes any one or a combination of 4,4'-diaminodiphenyl sulfide, 2,2'-diaminodiphenyl sulfide, 3,3'-dihydroxydiphenyl disulfide, and is not limited thereto.

[0040] Furthermore, the preparation method of the ureido-4-pyridone (UPy) chain extender includes:

[0041] Take 11.72 g of UPy (40 mmol) and 6.3 g of 2-amino-2-methyl-1,3-propanediol (60 mmol), mix them, add 420 mL of chloroform, and reflux for 5 h under a nitrogen atmosphere; after the reaction is completed, filter the product and wash it 3 times with chloroform; then transfer the solid to a beaker and add 200 mL of DMF to completely dissolve it; subsequently, centrifuge to take the supernatant (9000 rpm, 10 min), and add 500 mL of ether to precipitate it; finally, filter by suction and wash it 3 times with acetone, and vacuum dry it at 60 °C for 12 h to obtain the UPy chain extender (i.e., the ureido-4-pyridone (UPy) chain extender).

[0042] Further, the organic solvent includes any one or a combination of N,N-dimethylformamide, butyl acetate, dichloromethane, and is not limited thereto.

[0043] Further, the monomer containing an epoxy group includes any one or a combination of glycidol, glycidyl ether, resorcinol diglycidyl ether, and is not limited thereto.

[0044] Further, the polyetheramine curing agent includes any one or a combination of polyetheramine curing agent D230, polyetheramine curing agent D400, polyetheramine curing agent T403, and is not limited thereto.

[0045] Further, the molar ratio of the polyol to the monomer containing a dynamic chemical bond is 5:1 to 2:1.

[0046] Further, the molar ratio of the sum of the polyol and the monomer containing a dynamic chemical bond to the diisocyanate is 1:2 to 1:3.

[0047] Further, the mass-volume ratio of the polyol to the organic solvent is 2 g:1 mL to 5 g:1 mL.

[0048] In some preferred embodiments, the preparation method specifically includes:

[0049] Disperse Ti 3 C 2 T x -MXene nanosheets in Tris-buffer, then mix with dopamine and stir-react at 40 - 80 °C for 12 - 30 h, and then perform centrifugation to obtain dopamine-modified Ti 3 C 2 T x , and finally disperse it in N,N-dimethylformamide to obtain a dopamine-modified Ti 3 C 2 T x dispersion;

[0050] And, add a modifier containing a quadruple hydrogen bond motif to the dopamine-modified Ti 3 C 2 T x dispersion and reflux-react at 80 - 120 °C for 12 - 20 h to obtain modified Ti 3 C 2 T x two-dimensional nanosheets.

[0051] Further, the mass ratio of dopamine to Ti 3 C 2 T x -MXene nanosheets is 2:1 to 1:4.

[0052] Further, the concentration of the dopamine-modified Ti 3 C 2 T x dispersion is 1 - 20 mg / mL.

[0053] Further, the pH value of the Tris-buffer is 8.5.

[0054] Further, the mass ratio of the modifier containing a quadruple hydrogen bond motif to the dopamine-modified Ti 3 C 2 T x is 1:1 to 1:10.

[0055] Further, the Ti 3 C 2 Tx - The diameter of the MXene nanosheets is 0.2 - 5 μm, and the thickness is 0.6 - 15 nm.

[0056] Furthermore, the modifier containing a quadruple hydrogen bond motif includes, but is not limited to, ureido-4-pyridone (UPy).

[0057] In some preferred embodiments, the preparation method specifically includes: mixing the modified epoxy adaptable network material with modified Ti 3 C 2 T x two-dimensional nanosheets to undergo an interfacial ordered cross-linking reaction, and curing under the condition of evaporation-induced assistance to obtain a high-strength and tough seawater low-temperature environment self-healing epoxy coating.

[0058] Furthermore, the mass ratio of the modified epoxy adaptable network material to modified Ti 3 C 2 T x two-dimensional nanosheets is 1000:1 - 50:1.

[0059] Furthermore, the temperature used for the evaporation-induced assistance is 30 - 120 °C.

[0060] Furthermore, the time for the curing treatment is 24 - 72 h.

[0061] In some preferred embodiments, the preparation method of the high-strength and tough seawater low-temperature environment self-healing epoxy coating includes the following steps:

[0062] S1. Provide a modified epoxy adaptable network material

[0063] Introduce one or a combination of main-chain hydrogen bonds, side-chain quadruple hydrogen bonds, and disulfide bonds into the epoxy covalent network. After adding a curing agent to complete the curing reaction, a modified epoxy adaptable network material is obtained;

[0064] S2. Provide modified Ti 3 C 2 T x two-dimensional nanosheets

[0065] Add a modifier containing a quadruple hydrogen bond motif to the dopamine-modified Ti 3 C 2 T x dispersion liquid, and after reflux reaction, obtain modified Ti 3 C 2 T x two-dimensional nanosheets;

[0066] S3. Prepare a high-strength and tough seawater low-temperature environment self-healing epoxy coating

[0067] Mix the modified epoxy adaptable network material and modified Ti3 C 2 T x Two-dimensional nanosheets are crosslinked orderly at the interface and cured with the assistance of evaporation-induced to obtain a high-strength and tough epoxy coating with self-healing property in a low-temperature seawater environment.

[0068] Preferably, in step S1, the modified epoxy adaptable network material is preferably epoxy resin, and the preparation method of the modified epoxy adaptable network includes: blending polyol, diisocyanate, organic solvent and a monomer containing dynamic chemical bonds, and stirring at 50-120 °C for 1-6 h to obtain a prepolymer; adding a monomer containing an epoxy group to the prepolymer and stirring at 70-90 °C for 2-4 h to obtain an epoxy prepolymer; finally, adding a polyetheramine curing agent to the epoxy prepolymer and mixing to obtain epoxy resin.

[0069] Furthermore, the polyol includes at least one of polytetrahydrofuran (different molecular weights: PTMEG-250, PTMEG-650, PTMEG-1000, PTMEG-2000, PTMEG-3000) and polypropylene glycol (different molecular weights: PPG-400, PPG-1000, PPG-2000).

[0070] Furthermore, the diisocyanate includes one of alicyclic diisocyanate and aliphatic diisocyanate; more preferably, the alicyclic diisocyanate includes isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate (HMDI), toluene-2,5-diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), etc.; more preferably, the aliphatic diisocyanate includes hexamethylene diisocyanate (HDI), L-lysine diisocyanate (LDI), etc.

[0071] Furthermore, the organic solvent includes at least one of N,N-dimethylformamide (DMF), butyl acetate, and dichloromethane.

[0072] Furthermore, the monomer containing dynamic chemical bonds includes at least one of a chain extender containing ureido-4-pyridone (UPy) with a side-chain quadruple hydrogen bond motif and a diphenyl sulfide monomer containing a disulfide bond.

[0073] Furthermore, the monomer containing an epoxy group includes one of glycidol, glycidyl ether, and resorcinol diglycidyl ether.

[0074] Furthermore, the polyetheramine curing agent includes one of D230, D400, and T403 monomers.

[0075] Furthermore, the molar ratio of one or two combinations of the polyol and the monomer containing dynamic chemical bonds is 5:1 to 2:1.

[0076] Furthermore, the molar ratio of the total amount of the polyol + the monomer containing a dynamic chemical bond to the diisocyanate is 1:2 to 1:3.

[0077] Furthermore, the mass concentration of the polyol / organic solvent is 2 g / mL to 5 g / mL.

[0078] Preferably, in step S2, the mass ratio of the modifier containing a quadruple hydrogen bond motif to the dopamine-modified Ti 3 C 2 T x is 1:1 to 1:10; the mass ratio of the dopamine to the Ti 3 C 2 T x -MXene nanosheets is 2:1 to 1:4.

[0079] Furthermore, the dopamine-modified Ti 3 C 2 T x dispersion is a 1-20 mg / mL dopamine-modified Ti 3 C 2 T x / DMF dispersion; wherein, the diameter of the Ti 3 C 2 T x -MXene nanosheets is 0.2-5 μm, and the thickness is 0.6-15 nm.

[0080] Preferably, in step S3, the mass ratio of the modified epoxy adaptable network to the modified Ti 3 C 2 T x nanosheets is 1000:1 to 50:1.

[0081] Preferably, the temperature of the evaporation-induced assistance is 30-120 °C, and the curing time is 24-72 h.

[0082] In some more specific embodiments, the method for preparing the high-strength and tough seawater low-temperature environment self-healing epoxy coating includes the following steps:

[0083] 1) Preparation of the modified epoxy adaptable network material: Blend polyol, diisocyanate, organic solvent, and a monomer containing a dynamic chemical bond, and stir at 50-120 °C for 1-6 h to obtain a prepolymer; add a monomer containing an epoxy group to the prepolymer and stir at 70-90 °C for 2-4 h to obtain an epoxy prepolymer; finally, add a polyetheramine curing agent to the epoxy prepolymer and mix to obtain the modified epoxy adaptable network material;

[0084] 2) Modified Ti 3 C 2T x Two-dimensional nanosheets: A modifier containing a quadruple hydrogen bond motif is added to dopamine-modified Ti in a mass ratio of 1:1 to 1:10 3 C 2 T x in the dispersion liquid, and the mixture is refluxed at 80 - 120 °C for 12 - 20 h;

[0085] 3) Preparation of a high-strength and tough seawater low-temperature environment self-healing epoxy coating: A modified epoxy adaptable network material and modified Ti 3 C 2 T x nanosheets are mixed in a mass ratio of 1000:1 to 50:1, and cured at 40 - 100 °C for 10 - 60 h to obtain a high-strength and tough seawater low-temperature environment self-healing epoxy coating with a biomimetic nacre-inverse structure.

[0086] Another aspect of the embodiments of the present invention also provides a high-strength and tough seawater low-temperature environment self-healing epoxy coating prepared by the aforementioned preparation method, and the high-strength and tough seawater low-temperature environment self-healing epoxy coating has a biomimetic nacre-inverse structure.

[0087] In some preferred embodiments, due to the hydrophobic protection of the epoxy covalent network on various types of dynamic chemical bonds, the high-strength and tough seawater low-temperature environment self-healing epoxy coating has rapid self-healing ability at room temperature, low temperature (∼0 °C) and seawater environment (3.5 wt.% sodium chloride).

[0088] In some preferred embodiments, the high-strength and tough seawater low-temperature environment self-healing epoxy coating includes: a modified epoxy adaptable network material and modified Ti 3 C 2 T x two-dimensional nanosheets, wherein the modified Ti 3 C 2 T x two-dimensional nanosheets are arranged in a parallel manner in the epoxy coating through high-density quadruple hydrogen bonds at the interface between the two-dimensional nanosheets and the modified epoxy adaptable network material.

[0089] In some preferred embodiments, the high-strength and tough seawater low-temperature environment self-healing epoxy coating has various types of dynamic chemical bond networks and a hydrophobic epoxy covalent network.

[0090] Furthermore, the various types of dynamic chemical bonds are formed by combining any two or three of the introduced main-chain hydrogen bonds, side-chain quadruple hydrogen bonds, disulfide bonds, and interfacial hydrogen bonds.

[0091] Furthermore, due to the protection of the hydrophobic epoxy covalent network on various types of dynamic chemical bonds, the high-strength and tough seawater low-temperature environment self-healing epoxy coating exhibits rapid self-healing ability in various environments such as room temperature, low temperature, and seawater; the low-temperature condition is -10°C to 3°C; the seawater is a simulated seawater salinity water-based solution system containing 0.1 to 10 wt% brine.

[0092] Furthermore, the side-chain quadruple hydrogen bonds are obtained by introducing monomers containing side-chain quadruple hydrogen bond motifs in the molecular chain segments into the modified epoxy adaptable network.

[0093] Furthermore, the disulfide bonds are obtained by introducing monomers containing disulfide bonds into the modified epoxy adaptable network.

[0094] Furthermore, the interfacial quadruple hydrogen bonds are obtained by embedding modified Ti 3 C 2 T x Two-dimensional nanosheets to form interfacial hydrogen bonds.

[0095] In some preferred embodiments, the repair functions of the high-strength and tough seawater low-temperature environment self-healing epoxy coating include self-healing of mechanical properties and / or self-healing of corrosion protection functions in seawater low-temperature environments.

[0096] In some preferred embodiments, the tensile strength of the high-strength and tough seawater low-temperature environment self-healing epoxy coating is 20 to 35 MPa, and the toughness is 90 to 220 MJ·m -3 。

[0097] In some preferred embodiments, the tensile strength repair efficiency of the high-strength and tough seawater low-temperature environment self-healing epoxy coating at room temperature is 80 to 92%.

[0098] In some preferred embodiments, the tensile strength repair efficiency of the high-strength and tough seawater low-temperature environment self-healing epoxy coating at 0°C is 60 to 84%.

[0099] Another aspect of the embodiments of the present invention also provides an application of the aforementioned high-strength and tough seawater low-temperature environment self-healing epoxy coating in the fields of metal surface coating self-healing-corrosion protection or flexible sensors in seawater low-temperature environments.

[0100] Furthermore, the temperature of the seawater low-temperature environment is -10°C to 3°C; the seawater in the seawater low-temperature environment is a simulated seawater salinity water-based solution system containing 0.1 to 10 wt% brine.

[0101] The present invention prepares a high-strength and tough seawater low-temperature environment self-healing epoxy coating by synergistically combining main-chain hydrogen bonds, side-chain quadruple hydrogen bonds, disulfide bonds, and interfacial hydrogen bonds. Among them, modified Ti 3C 2 T x Due to the introduction of high-density quadruple hydrogen bonds at the interface, the nanosheets are arranged in a parallel manner in the epoxy coating. The self-healing epoxy coating exhibits high mechanical strength, excellent toughness, and rapid self-healing ability under low-temperature seawater environment due to the synergistic effect of multiple types of dynamic chemical bonds and the biomimetic inverse nacre structure, as well as the hydrophobic protection of the epoxy covalent network for chemical bonds; specifically, the tensile strength of the self-healing epoxy coating is 20-35 MPa, and the toughness is 90-220 MJ·m -3 ; and the tensile strength of the epoxy coating cut into two sections can recover 80-92% after contacting for 0.5-12 h at room temperature, and can recover 60-84% after contacting for 0.5-12 h at 0 °C, successfully balancing the contradiction among high mechanical strength, strong toughness, and self-healing ability in the self-healing coating.

[0102] The technical solution of the present invention will be further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. These embodiments are implemented on the premise of the technical solution of the invention, and the detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0103] The experimental materials used in the following embodiments can be purchased from conventional biochemical reagent companies without special instructions.

[0104] The UPy chain extender and the preparation method of UPy used in the following examples are all prepared by the following methods:

[0105] The preparation method of the UPy chain extender includes: taking 11.72 g of UPy (40 mmol) and 6.3 g of 2-amino-2-methyl-1,3-propanediol (60 mmol), mixing them, adding 420 mL of chloroform, and refluxing for 5 h under a nitrogen atmosphere; after the reaction is completed, filtering the product and washing it 3 times with chloroform; then transferring the solid to a beaker and adding 200 mL of DMF to completely dissolve it; subsequently, centrifuging and separating to take the supernatant (9000 rpm, 10 min), adding 500 mL of ether to precipitate it; finally, filtering with suction and washing it 3 times with acetone, and drying it in vacuo at 60 °C for 12 h to obtain the UPy chain extender;

[0106] The preparation method of UPy includes: taking 10 g of 6-methylisocytosine (80 mmol) and 80.64 g of hexamethylene diisocyanate (HDI, 480 mmol) in a single-neck flask, refluxing and reacting at 100 °C for 12 h under a nitrogen atmosphere; after the reaction is completed, precipitating it with 400 mL of pentane, filtering and washing it 3 times with acetone, and drying it in vacuo at 50 °C for 12 h to obtain UPy powder.

[0107] Example 1

[0108] A preparation method of a high-strength and tough self-healing epoxy coating for seawater at low temperature. In this example, epoxy resin is used as the matrix material for illustration. Refer to Figure 1 , which is the preparation roadmap of the high-strength and tough self-healing epoxy coating for seawater at low temperature. As shown in Figure 1 , PTMEG-1000 (polytetrahydrofuran, molecular weight 1000 g / mol), UPy chain extender containing side-chain quadruple hydrogen bond motifs, 4,4'-diaminodiphenyl sulfide containing disulfide bonds, IPDI (isophorone diisocyanate), and DMF (N,N-dimethylformamide) are mixed and reacted at 80 °C for 3 h under a nitrogen atmosphere to obtain a prepolymer; then a monomer containing an epoxy group is introduced into the prepolymer and stirred continuously at 80 °C for 3 h to obtain an epoxy prepolymer; finally, a polyetheramine curing agent is added to the epoxy prepolymer and mixed to obtain an epoxy adaptable network; the modified Ti 3 C 2 T x two-dimensional nanosheets are mixed with the modified epoxy adaptable network and cured to obtain the high-strength and tough self-healing epoxy coating for seawater at low temperature.

[0109] Specifically, the preparation method includes the following steps:

[0110] 1. Preparation of the modified epoxy adaptable network: Take 96 g of PTMEG-1000 (96 mmol), 4.776 g of UPy chain extender (12 mmol), 2.98 g of 4,4'-diaminodiphenyl sulfide (12 mmol), 53.35 g of IPDI (240 mmol), and 40 mL of DMF and mix them. React at 80 °C for 3 h under a nitrogen atmosphere to obtain a prepolymer; after the reaction, add 17.78 g of glycidol (240 mmol) and continue to react at 80 °C for 3 h to obtain an epoxy prepolymer; finally, add 13.8 g of D230 (60 mmol) and mix to obtain a modified epoxy adaptable network containing main-chain hydrogen bonds, side-chain quadruple hydrogen bonds, and disulfide bonds;

[0111] 2. Modification of Ti 3 C 2 T x two-dimensional nanosheets: Add UPy containing quadruple hydrogen bond motifs with a mass ratio of 1:5 to the 1 mg / mL dopamine-modified Ti 3 C 2 T x / DMF dispersion liquid, reflux and react at 100 °C for 16 h to obtain modified Ti 3 C 2 T x two-dimensional nanosheets; among them, the mass ratio of dopamine to Ti 3 C 2 T x is 1:2;

[0112] Among them, the preparation method of dopamine-modified Ti 3 C 2 T x includes: taking 0.8 g of Ti 3 C 2 T x -MXene nanosheets and adding them to 400 mL of Tris-buffer with pH = 8.5 for ultrasonic dispersion for 30 min, then adding 0.4 g of dopamine and stirring at 60 °C for 24 h; after the reaction, the solution is centrifuged and washed 3 times with deionized water and DMF respectively to obtain dopamine-modified Ti 3 C 2 T x nanosheets.

[0113] 3. Preparation of a high-strength and tough seawater low-temperature environment self-healing epoxy coating: Mixing the modified epoxy adaptable network and modified Ti 3 C 2 T x two-dimensional nanosheets with a mass ratio of 200:1, curing at 40 °C and 50 °C for 12 h respectively first, and then curing at 60 °C for 30 h to obtain a high-strength and tough seawater low-temperature environment self-healing epoxy coating with an interfacial quadruple hydrogen bond and a biomimetic nacreous layer structure.

[0114] Refer to Figure 1 , which is the synthesis route diagram of the modified epoxy adaptable network described in this example;

[0115] As Figure 2 shown is the scanning electron micrograph of the high-strength and tough seawater low-temperature environment self-healing epoxy coating provided in this example. Obviously, the modified Ti 3 C 2 T x two-dimensional nanosheets are arranged in the epoxy resin in a parallel arrangement. The design of this biomimetic structure and the introduction of high-density quadruple hydrogen bonds at the epoxy / Ti 3 C 2 T x interface are beneficial to improving the mechanical strength and toughness of the epoxy self-healing coating.

[0116] Refer to Figure 3 , which is the stress-strain curve of the mechanical property tensile test of the high-strength and tough seawater low-temperature environment self-healing epoxy coating in this example. As can be seen from the figure, its ultimate tensile strength and toughness are as high as 34.5 MPa and 210.75 MJ·m -3 , respectively, showing excellent toughness.

[0117] After the self-healing material was cut into two sections and contacted for 2 hours at room temperature and 0 °C respectively, the ultimate tensile strength of the material could be restored by 90.4% and 81.5% respectively. This shows the synergistic effect of the main-chain hydrogen bonds, side-chain quadruple hydrogen bonds, disulfide bonds and interfacial hydrogen bonds in the epoxy adaptation network of this example, and thus has fast self-healing ability at room temperature and low temperature.

[0118] See Figure 4 and Figure 5 , which are the scanning electron microscope images of the self-healing material after being cut into two sections and contacted at room temperature for 2 hours and the tensile test stress-strain curves after being repaired at different temperatures respectively.

[0119] This example also investigated the self-healing behavior of the self-healing coating in a low-temperature simulated seawater environment (~0 °C, 3.5 wt.% brine). As Figure 6a - Figure 6b shown, the autonomous repair of the coating corrosion protection function can also be achieved in the low-temperature seawater environment, showing excellent self-healing ability in the water environment and low-temperature environment.

[0120] By virtue of the high conductivity of the modified Ti 3 C 2 T x two-dimensional nanosheets and the excellent tensile properties and water environment-insensitive characteristics of the self-healing epoxy coating, an underwater sensor was assembled, which can show sensitive and stable resistance change behaviors at different finger bending angles in the air / water environment. As Figure 7 shown.

[0121] In summary, the high-strength and tough seawater low-temperature environment self-healing epoxy coating prepared in this example has broad application prospects in the fields of marine environment metal surface corrosion protection, flexible sensors, etc.

[0122] Example 2

[0123] A preparation method of a high-strength and tough seawater low-temperature environment self-healing epoxy coating includes the following steps:

[0124] 1. Preparation of the modified epoxy adaptation network: Take 100 g of PPG-2000 (polypropylene glycol, molecular weight 2000 g / mol, 50 mmol), 2.388 g of UPy chain extender (6 mmol), 0.993 g of 2,2'-diaminodiphenyl sulfide (4 mmol), 45.05 g of HMDI (dicyclohexylmethane-4,4'-diisocyanate, 180 mmol) and 50 mL of butyl acetate and mix them. React at 50 °C for 6 hours under a nitrogen atmosphere to obtain a prepolymer; after the reaction is completed, add 46.85 g of glycidyl ether (180 mmol), and continue to react at 90 °C for 2 hours to obtain an epoxy prepolymer; finally, add 12 g of D400 (30 mmol) and mix to obtain a modified epoxy adaptation network containing main-chain hydrogen bonds, side-chain quadruple hydrogen bonds and disulfide bonds;

[0125] 2. Ti 3 C 2 T x Modification of two-dimensional nanosheets: UPy containing quadruple hydrogen bond motifs with a mass ratio of 1:1 was added to 10 mg / mL dopamine-modified Ti 3 C 2 T x / DMF dispersion, and the reflux reaction was carried out at 120 °C for 12 h to obtain modified Ti 3 C 2 T x two-dimensional nanosheets; wherein, the mass ratio of dopamine to Ti 3 C 2 T x is 2:1;

[0126] 3. Preparation of high-strength and tough seawater low-temperature environment self-healing epoxy coating: Mix the modified epoxy adaptable network and modified Ti 3 C 2 T x two-dimensional nanosheets with a mass ratio of 1000:1, and cure at 120 °C for 24 h to obtain a high-strength and tough seawater low-temperature environment self-healing epoxy coating with interfacial quadruple hydrogen bonds and a biomimetic inverse nacre structure.

[0127] The mechanical properties and self-healing ability of the epoxy self-healing coating prepared in this example are equivalent to those of Example 1.

[0128] Example 3

[0129] A preparation method of a high-strength and tough seawater low-temperature environment self-healing epoxy coating, comprising the following steps:

[0130] 1. Preparation of modified epoxy adaptable network: Take 20 g of PTMEG-250 (molecular weight 250 g / mol, 80 mmol), 6.368 g of UPy chain extender (16 mmol), 6.008 g of 3,3'-dihydroxydiphenyl sulfide (24 mmol), 52.25 g of TDI (toluene-2,5-diisocyanate, 300 mmol) and 10 mL of dichloromethane and mix them. React at 120 °C for 1 h under a nitrogen atmosphere to obtain a prepolymer; after the reaction, add 46.85 g of resorcinol diglycidyl ether (150 mmol) and continue to react at 70 °C for 4 h to obtain an epoxy prepolymer; finally, add 33.75 g of T403 (75 mmol) and mix to obtain a modified epoxy adaptable network containing main-chain hydrogen bonds, side-chain quadruple hydrogen bonds and disulfide bonds;

[0131] 2. Ti 3 C 2 T xModification of two-dimensional nanosheets: Add UPy containing a quadruple hydrogen bond motif with a mass ratio of 1:10 to the dopamine-modified Ti in a 20 mg / mL dispersion in DMF, and reflux and react at 80 °C for 20 h to obtain the modified Ti 3 C 2 T x / DMF dispersion, and reflux and react at 80 °C for 20 h to obtain the modified Ti 3 C 2 T x two-dimensional nanosheets; wherein, the mass ratio of dopamine to Ti 3 C 2 T x is 1:4;

[0132] 3. Preparation of a high-strength and tough self-healing epoxy coating for seawater at low temperatures: Mix the modified epoxy adaptable network and the modified Ti 3 C 2 T x two-dimensional nanosheets with a mass ratio of 50:1, and cure at 30 °C for 72 h to obtain a high-strength and tough self-healing epoxy coating with interfacial quadruple hydrogen bonds and a biomimetic inverse nacre structure for seawater at low temperatures.

[0133] Example 4

[0134] A method for preparing a high-strength and tough self-healing epoxy coating for seawater at low temperatures, comprising the following steps:

[0135] 1. Preparation of the modified epoxy adaptable network: Take 60 g of PTMEG-3000 (molecular weight 3000 g / mol, 20 mmol), 3.98 g of UPy chain extender (10 mmol), 11.312 g of LDI (L-lysine diisocyanate, 50 mmol) and 12 mL of DMF and mix them. React at 100 °C for 2 h under a nitrogen atmosphere to obtain a prepolymer; after the reaction is completed, add 15.62 g of resorcinol diglycidyl ether (50 mmol) and continue to react at 75 °C for 3.5 h to obtain an epoxy prepolymer; finally, add 10 g of D400 (25 mmol) and mix to obtain a modified epoxy adaptable network containing main-chain hydrogen bonds and side-chain quadruple hydrogen bonds;

[0136] 2. Modification of Ti 3 C 2 T x two-dimensional nanosheets: Add UPy containing a quadruple hydrogen bond motif with a mass ratio of 1:3 to the dopamine-modified Ti 3 C 2 T x / DMF dispersion, and reflux and react at 90 °C for 18 h to obtain the modified Ti 3 C 2 T x two-dimensional nanosheets; wherein, the mass ratio of dopamine to Ti 3 C 2 Tx The mass ratio is 1:1;

[0137] 3. Preparation of a high-strength and tough epoxy coating with self-healing property in low-temperature seawater environment: Mix a modified epoxy adaptable network and modified Ti 3 C 2 T x two-dimensional nanosheets with a mass ratio of 100:1, cure at 60 °C for 56 h, and obtain a high-strength and tough epoxy coating with self-healing property in low-temperature seawater environment and having an interfacial quadruple hydrogen bond and a biomimetic nacreous layer structure.

[0138] Example 5

[0139] A preparation method of a high-strength and tough epoxy coating with self-healing property in low-temperature seawater environment, comprising the following steps:

[0140] 1. Preparation of a modified epoxy adaptable network: Take 100 g of PTMEG-2000 (molecular weight 2000 g / mol, 50 mmol), 3.184 g of UPy chain extender (8 mmol), 1.987 g of 4,4′-diaminodiphenyl sulfide (8 mmol), 29.343 g of IPDI (132 mmol) and 25 mL of DMF, mix them, and react at 60 °C for 5 h in a nitrogen atmosphere to obtain a prepolymer; after the reaction is completed, add 41.237 g of resorcinol diglycidyl ether (132 mmol), and continue to react at 85 °C for 2.5 h to obtain an epoxy prepolymer; finally, add 7.59 g of D230 (33 mmol) and mix to obtain a modified epoxy adaptable network containing main-chain hydrogen bonds, side-chain quadruple hydrogen bonds and disulfide bonds;

[0141] 2. Modification of Ti 3 C 2 T x two-dimensional nanosheets: Add UPy containing a quadruple hydrogen bond motif with a mass ratio of 1:8 to a 15 mg / mL dopamine-modified Ti 3 C 2 T x / DMF dispersion liquid, reflux and react at 110 °C for 14 h to obtain modified Ti 3 C 2 T x two-dimensional nanosheets; wherein, the mass ratio of dopamine to Ti 3 C 2 T x is 1:3;

[0142] 3. Preparation of a high-strength and tough epoxy coating with self-healing property in low-temperature seawater environment: Mix a modified epoxy adaptable network and modified Ti 3 C 2 T xThe two-dimensional nanosheets were mixed and cured at 80 °C for 48 h to obtain a high-strength and tough seawater low-temperature environment self-healing epoxy coating with interfacial quadruple hydrogen bonds and a biomimetic inverse nacre structure.

[0143] Comparative Example 1

[0144] A preparation method of a room-temperature self-healing epoxy coating includes the following steps:

[0145] Take 96 g of PTMEG-1000 (96 mmol), 4.776 g of UPy chain extender (12 mmol), 2.98 g of 4,4′-diaminodiphenyl sulfide (12 mmol), 53.35 g of IPDI (240 mmol) and 40 mL of DMF and mix them. React at 80 °C for 3 h under a nitrogen atmosphere to obtain a prepolymer; after the reaction is completed, add 17.78 g of glycidol (240 mmol) and continue to react at 80 °C for 3 h to obtain an epoxy prepolymer; finally, add 13.8 g of D230 (60 mmol), stir well and pour it into a mold, cure at 40 °C and 50 °C for 12 h respectively, and then cure at 60 °C for 30 h to obtain a modified epoxy coating containing main-chain hydrogen bonds, side-chain quadruple hydrogen bonds and disulfide bonds.

[0146] After the prepared epoxy coating is contacted for 2 h at room temperature and 0 °C respectively, the ultimate tensile strength of the material can be restored by 92.4% and 84.1% respectively, showing a rapid self-healing ability; however, its ultimate tensile strength and toughness value are relatively low, which are 20.2 MPa and 94.4 MJ·m -3 .

[0147] Comparative Example 2

[0148] A preparation method of a room-temperature self-healing epoxy coating includes the following steps:

[0149] Take 100 g of PPG-2000 (polypropylene glycol, molecular weight 2000 g / mol, 50 mmol), 2.388 g of UPy chain extender (6 mmol), 0.993 g of 2,2′-diaminodiphenyl sulfide (4 mmol), 45.05 g of HMDI (dicyclohexylmethane-4,4’-diisocyanate, 180 mmol) and 50 mL of butyl acetate and mix them. React at 50 °C for 6 h under a nitrogen atmosphere to obtain a prepolymer; after the reaction is completed, add 46.85 g of glycidyl ether (180 mmol) and continue to react at 90 °C for 2 h to obtain an epoxy prepolymer; finally, add 12 g of D400 (30 mmol), stir well and pour it into a mold, and cure at 120 °C for 24 h to obtain a modified epoxy coating containing main-chain hydrogen bonds, side-chain quadruple hydrogen bonds and disulfide bonds.

[0150] The result of this comparative example is comparable to that of Comparative Example 1, having room-temperature self-healing ability, but with poor mechanical properties.

[0151] Comparative Example 3

[0152] A method for preparing an epoxy coating includes the following steps:

[0153] Take 60 g of PTMEG-3000 (molecular weight 3000 g / mol, 20 mmol), 3.98 g of UPy chain extender (10 mmol), 11.312 g of LDI (L-lysine diisocyanate, 50 mmol) and 12 mL of DMF, mix them, and react at 100 °C for 2 h under a nitrogen atmosphere to obtain a prepolymer; after the reaction is completed, add 15.62 g of resorcinol diglycidyl ether (50 mmol), and continue to react at 75 °C for 3.5 h to obtain an epoxy prepolymer; finally, add 10 g of D400 (25 mmol), stir well and pour it into a mold, and cure at 60 °C for 56 h to obtain a modified epoxy coating containing main-chain hydrogen bonds and side-chain quadruple hydrogen bonds.

[0154] The result of this comparative example is comparable to that of Comparative Example 1, having room-temperature self-healing ability, but poor mechanical properties.

[0155] Comparative Example 4

[0156] A method for preparing a self-healing epoxy coating includes the following steps:

[0157] Take 96 g of PTMEG-1000 (96 mmol), 4.776 g of UPy chain extender (12 mmol), 2.98 g of 4,4′-diaminodiphenyl sulfide (12 mmol), 53.35 g of IPDI (240 mmol) and 40 mL of DMF, mix them, and react at 80 °C for 3 h under a nitrogen atmosphere to obtain a prepolymer; after the reaction is completed, add 17.78 g of glycidol (240 mmol), and continue to react at 80 °C for 3 h to obtain an epoxy prepolymer; then, add 13.8 g of D230 (60 mmol) to obtain a modified epoxy adaptable network containing main-chain hydrogen bonds, side-chain quadruple hydrogen bonds and disulfide bonds; finally, mix the modified epoxy adaptable network and Ti 3 C 2 T x -MXene two-dimensional nanosheets in a mass ratio of 200:1, first cure at 40 °C and 50 °C for 12 h respectively, and then cure at 60 °C for 30 h to obtain a self-healing epoxy coating.

[0158] Compared with Comparative Example 1, this comparative example does not form interfacial quadruple hydrogen bonds and a biomimetic inverse nacreous layer structure, and the nanosheets are not evenly dispersed; its ultimate tensile strength is less than 20 MPa, and the samples broken into two sections need to be in contact at room temperature for 12 h to recover more than 80% of the mechanical strength.

[0159] Comparative Example 5

[0160] A preparation method of an epoxy coating, comprising the following steps:

[0161] Take 17.78 g of glycidyl (240 mmol) and 13.8 g of D230 (60 mmol) and mix them to obtain an epoxy network; then mix the epoxy network and modified Ti 3 C 2 T x two-dimensional nanosheets with a mass ratio of 200:1, cure at 40 °C and 50 °C for 12 h respectively, and then cure at 60 °C for 30 h to obtain an epoxy coating.

[0162] Among them, the modification method of Ti 3 C 2 T x two-dimensional nanosheets is as follows: add UPy containing a quadruple hydrogen bond motif with a mass ratio of 1:5 to a 1 mg / mL dopamine-modified Ti 3 C 2 T x / DMF dispersion liquid, reflux and react at 100 °C for 16 h to obtain modified Ti 3 C 2 T x two-dimensional nanosheets; among them, the mass ratio of dopamine to Ti 3 C 2 T x is 1:2;

[0163] Among them, the preparation method of dopamine-modified Ti 3 C 2 T x includes: take 0.8 g of Ti 3 C 2 T x -MXene nanosheets and add them to 400 mL of Tris-buffer buffer solution with pH = 8.5, ultrasonically disperse for 30 min, then add 0.4 g of dopamine, and stir at 60 °C for 24 h; after the reaction is completed, centrifuge the solution and wash it 3 times with deionized water and DMF respectively to obtain dopamine-modified Ti 3 C 2 T x nanosheets.

[0164] In the prepared epoxy coating, the modified Ti 3 C 2 T x two-dimensional nanosheets are unevenly dispersed, the material has high mechanical strength but low toughness and no self-healing ability.

[0165] Comparative Example 6

[0166] A preparation method of a self-healing epoxy coating, comprising the following steps:

[0167] 96 g of PTMEG-1000 (96 mmol), 5.96 g of 4,4'-diaminodiphenyl sulfide (24 mmol), 53.35 g of IPDI (240 mmol) and 40 mL of DMF were mixed and reacted at 80 °C for 3 h under a nitrogen atmosphere to obtain a prepolymer; after the reaction, 17.78 g of glycidol (240 mmol) was added and the reaction was continued at 80 °C for 3 h to obtain an epoxy prepolymer; finally, 13.8 g of D230 (60 mmol) was added, and after sufficient stirring, it was poured into a mold and cured at 40 °C and 50 °C for 12 h respectively, and then cured at 60 °C for 30 h to obtain a modified epoxy coating containing main-chain hydrogen bonds and disulfide bonds.

[0168] This comparative example has a self-healing ability comparable to that of Comparative Example 1, but has poor mechanical properties.

[0169] In summary, the present invention prepares a high-strength and tough seawater low-temperature environment self-healing epoxy coating by synergistically combining main-chain hydrogen bonds, side-chain quadruple hydrogen bonds, disulfide bonds, and interfacial hydrogen bonds. Among them, the modified Ti 3 C 2 T x nanosheets are arranged in the epoxy coating in a parallel arrangement due to the introduction of high-density quadruple hydrogen bonds at the interface. The self-healing epoxy coating exhibits high mechanical strength, excellent toughness, and rapid self-healing ability in a seawater low-temperature environment due to the synergistic effect of multiple types of dynamic chemical bonds and the biomimetic nacre-inverse structure, as well as the hydrophobic protection of the epoxy covalent network for chemical bonds; specifically, the tensile strength of the self-healing epoxy coating is 20-35 MPa, and the toughness is 90-220 MJ m -3 ; and the tensile strength of the epoxy coating cut into two sections can recover 80% to 92% after contacting at room temperature for 0.5 to 12 h, and can recover 60% to 84% after contacting at 0 °C for 0.5 to 12 h. The contradiction between high mechanical strength, high toughness, and self-healing ability in the self-healing coating is successfully balanced.

[0170] In addition, the inventors of this case also referred to the foregoing embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and all obtained relatively ideal results.

[0171] It should be understood that the technical solutions of the present invention are not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solutions of the present invention without departing from the spirit of the present invention and the scope protected by the claims falls within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength and tough seawater low-temperature environment self-repairing epoxy coating, characterized in that: include: A modified epoxy adaptive network material is provided; wherein the modified epoxy adaptive network material comprises any one or more combinations of main chain hydrogen bonds, side chain quadruple hydrogen bonds, and disulfide bonds; the modified epoxy adaptive network material is prepared by reacting epoxy resin, polyol, diisocyanate, and monomers containing dynamic chemical bonds; Provide modified Ti3C2T x Two-dimensional nanosheet; wherein the modified Ti3C2T x The two-dimensional nanosheets are made of dopamine, a modifier containing a quadruple hydrogen bond motif, and Ti3C2T x -MXene obtained; And, the modified epoxy adaptive network material and the modified Ti3C2T x The two-dimensional nanosheets are mixed to produce an orderly interfacial cross-linking reaction to produce a high-strength and tough self-healing epoxy coating that can withstand low-temperature seawater environments.

2. The preparation method according to claim 1, characterized in that: Specifically include: The polyol, diisocyanate, monomer containing dynamic chemical bonds and organic solvent are mixed and stirred at 50-120° C. for 1-6 hours to prepare a prepolymer; Adding a monomer containing an epoxy group to the prepolymer and stirring the mixture at 70 to 90° C. for 2 to 4 hours to obtain an epoxy prepolymer; And, a polyetheramine curing agent is added to the epoxy prepolymer to prepare a modified epoxy adaptive network material.

3. The preparation method according to claim 2, characterized in that: The polyol includes polytetrahydrofuran and / or polypropylene glycol; And / or, the diisocyanate includes alicyclic diisocyanate and / or aliphatic diisocyanate; the alicyclic diisocyanate includes any one or more combinations of isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, toluene-2,5-diisocyanate, 4,4'-diphenylmethane diisocyanate; the aliphatic diisocyanate includes hexamethylene diisocyanate and / or L-lysine diisocyanate; And / or, the monomer containing dynamic chemical bonds includes a monomer containing a side chain quadruple hydrogen bond motif and / or a monomer containing a disulfide bond; the monomer containing a side chain quadruple hydrogen bond motif includes a urea-4-pyridone chain extender; the monomer containing a disulfide bond includes any one or more combinations of 4,4′-diaminodiphenyl sulfide, 2,2′-diaminodiphenyl sulfide, and 3,3′-dihydroxydiphenyl disulfide; And / or, the organic solvent includes any one or more combinations of N,N-dimethylformamide, butyl acetate, and dichloromethane; And / or, the epoxy group-containing monomer includes any one or more combinations of glycidol, glycidyl ether, and resorcinol diglycidyl ether; And / or, the polyetheramine curing agent includes any one or more combinations of polyetheramine curing agent D230, polyetheramine curing agent D400, and polyetheramine curing agent T403; and / or, the molar ratio of the polyol to the monomer containing dynamic chemical bonds is 5:1 to 2:1; And / or, the molar ratio of the sum of the polyol and the monomer containing dynamic chemical bonds to the diisocyanate is 1:2 to 1:3; And / or, the mass volume ratio of the polyol to the organic solvent is 2g:1mL to 5g:1mL.

4. The preparation method according to claim 1, characterized in that: Specifically include: Ti3C2T x -MXene nanosheets were dispersed in Tris-buffer, mixed with dopamine and stirred at 40-80°C for 12-30h, and then centrifuged to obtain dopamine-modified Ti3C2T x , and finally dispersed in N,N-dimethylformamide to obtain dopamine-modified Ti3C2T x Dispersion liquid; and adding a modifier containing a quadruple hydrogen bonding motif to the dopamine-modified Ti3C2T x The dispersion was refluxed at 80-120°C for 12-20h to obtain modified Ti3C2T x Two-dimensional nanosheets.

5. The preparation method according to claim 4, characterized in that: The dopamine and Ti3C2T x -The mass ratio of MXene nanosheets is 2:1 to 1:4; And / or, the dopamine-modified Ti3C2T x The concentration of the dispersion is 1 to 20 mg / mL; And / or, the modifier containing quadruple hydrogen bond motif and dopamine modified Ti3C2T x The mass ratio is 1:1~1:10; and / or, the Ti3C2T x -MXene nanosheets have a diameter of 0.2 to 5 μm and a thickness of 0.6 to 15 nm; And / or, the modifier containing a quadruple hydrogen bonding motif comprises ureido-4-pyridone.

6. The preparation method according to claim 1, characterized in that: Specifically include: Modified epoxy adaptive network material and modified Ti3C2T x The two-dimensional nanosheets are mixed to produce an orderly interfacial cross-linking reaction, and are cured under evaporation-induced auxiliary conditions to produce a high-strength and tough self-healing epoxy coating in a low-temperature seawater environment.

7. The preparation method according to claim 6, characterized in that: The modified epoxy adaptable network material and the modified Ti3C2T x The mass ratio of the two-dimensional nanosheets is 1000:1 to 50:1; And / or, the temperature used for the evaporation induction assistance is 30 to 120°C; And / or, the curing treatment time is 24 to 72 hours.

8. The high-toughness seawater low-temperature environment self-repairing epoxy coating prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The high-strength and tough seawater low-temperature environment self-repairing epoxy coating has a bionic anti-pearl structure.

9. The high-toughness seawater low-temperature environment self-repairing epoxy coating according to claim 8, characterized in that: The high-strength and toughness self-repairing epoxy coating in low-temperature seawater environment has a tensile strength of 20 to 35 MPa and a toughness of 90 to 220 MJ.m- 3 ; And / or, the tensile strength repair efficiency of the high-toughness seawater low-temperature environment self-repairing epoxy coating at room temperature is 80-92%; And / or, the tensile strength repair efficiency of the high-toughness seawater low-temperature environment self-repairing epoxy coating at 0°C is 60-84%.

10. Application of the high-strength and tough seawater low-temperature environment self-repairing epoxy coating according to claim 8 or 9 in the field of metal surface coating self-repairing-corrosion protection or flexible sensors in seawater low-temperature environments.

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