A self-healing underwater concrete material containing dynamic disulfide bonds, its preparation method and application

Abstract

This invention belongs to the field of marine engineering materials technology, specifically relating to an underwater self-healing concrete material containing dynamic disulfide bonds, its preparation method, and its application. The underwater self-healing concrete material containing dynamic disulfide bonds of this invention comprises, by weight, the following components: a hardener, wherein the hardener is an epoxy prepolymer containing dynamic disulfide bonds (50-70 parts); and a hydrophobic agent, comprising a curing agent (20-35 parts) and an accelerator (1-3 parts). The underwater self-healing concrete material containing dynamic disulfide bonds of this invention uses an epoxy prepolymer containing dynamic disulfide bonds as the main network. When broken under external force, it can subsequently repair microcracks through spontaneous recombination to form new covalent bonds.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering materials technology, specifically relating to an underwater concrete self-healing material containing dynamic disulfide bonds, its preparation method, and its application. Background Technology

[0002] The number of large-scale cross-sea bridges, deep-sea drilling platforms, and subsea tunnels is rapidly increasing. These structures are exposed to complex marine environments for extended periods, enduring the combined effects of seawater erosion, wave impact, and tidal cycles. Statistics show that the service life of marine concrete structures is significantly shorter than that of similar terrestrial structures, especially in areas with alternating exposure such as tidal zones and splash zones, where material degradation rates can be 3-5 times faster than inland areas. Traditional repair materials face numerous challenges in these extreme environments. Conventional epoxy resins struggle to achieve ideal curing in seawater, and the curing process is highly susceptible to factors such as temperature, humidity, and water flow, leading to incomplete curing and insufficient strength. Currently, most epoxy materials on the market typically have a curing degree of less than 70% underwater, severely impacting their long-term service performance. Furthermore, the interfacial bond strength between existing repair materials and the concrete matrix in seawater decays rapidly. After 50-100 wet-dry cycles, the bond strength retention rate is often below 65%, failing to meet the 15-20 year design service life requirements for marine engineering projects. High concentrations of chloride ions in seawater are a major factor causing corrosion of reinforced concrete structures, and the chloride ion diffusion coefficient of existing repair materials is generally between 10⁻⁶ and 10⁻⁶. 10 m 2 The pressure is on the order of / s, making it difficult to effectively prevent chloride ions from penetrating into the interior, causing the repair effect to be destroyed in a short period of time. In addition, in marine environments, structures are subjected to dynamic water pressure and wave impact for a long time, which makes repair materials prone to micro-cracks. Once traditional materials crack, they cannot achieve self-healing and must be repaired again, which significantly increases maintenance costs.

[0003] Currently, various underwater epoxy repair materials are available on the market. While the addition of hydrophilic components improves the wettability of these materials underwater, their curing time is generally long, typically requiring more than 7 days to reach sufficient strength, and the curing degree in seawater is only around 65%. Some microcapsule-containing self-healing composites possess a certain degree of self-healing ability, but the microcapsules are easily lost underwater, resulting in a repair efficiency generally below 50%, which is insufficient to meet practical engineering needs. Existing marine engineering anti-corrosion materials, although providing good chloride ion barrier performance, lack an active repair mechanism and have a limited service life. Some self-healing epoxy materials containing dynamic bonds require external thermal stimulation to trigger the repair process, making them unsuitable for marine engineering environments where human intervention is difficult. Microcapsule-based self-healing composites exhibit poor microcapsule stability in high-humidity environments, resulting in unsatisfactory long-term performance. Some underwater-curing epoxy systems rely on high temperatures to promote curing, leading to insufficient curing degree in low-temperature seawater environments.

[0004] With the expansion of marine engineering projects and the extension of their service life, existing technologies can no longer meet the needs of long-term repair of marine concrete structures. Therefore, there is an urgent need to develop a new material system that can rapidly cure in complex seawater environments, has efficient self-healing capabilities, and resists chloride ion penetration for a long time, in order to solve the above-mentioned technical problems, extend the service life of marine engineering structures, reduce maintenance costs, and improve engineering safety.

[0005] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0006] The purpose of this invention is to provide an underwater concrete self-healing material containing dynamic disulfide bonds, its preparation method, and its application, so as to help solve or improve at least one of the problems of existing concrete repair materials in seawater environment, such as difficulty in rapid curing, poor self-healing ability, and difficulty in resisting chloride ion penetration for a long time.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an underwater concrete self-healing material containing dynamic disulfide bonds, comprising the following components by weight: a hardener, wherein the hardener is 50-70 parts of an epoxy prepolymer containing dynamic disulfide bonds; and a hydrophobic agent, comprising 20-35 parts of a curing agent and 1-3 parts of an accelerator.

[0008] Preferably, the epoxy prepolymer containing dynamic disulfide bonds is prepared by a method comprising the following steps: A1. Mixing 4,4'-diaminodiphenyl disulfide with bisphenol A type epoxy resin and reacting under nitrogen protection to obtain a first intermediate product; A2. Adding 1,4-butanediol diglycidyl ether to extend the chain of the first intermediate product to obtain a second intermediate product; A3. Precipitating and purifying the second intermediate product to obtain the epoxy prepolymer containing dynamic disulfide bonds.

[0009] Preferably, in step A1, the molar ratio of 4,4'-diaminodiphenyl disulfide to bisphenol A type epoxy resin is 1:(2-3); the reaction temperature is 80-100℃, and the reaction time is 4-6h; in step A2, the chain extension degree is controlled at 10%-15%; in step A3, the epoxy value of the epoxy prepolymer containing dynamic disulfide bonds is 0.25-0.35eq / 100g.

[0010] Preferably, in step A1, the epoxy value of the bisphenol A type epoxy resin is 0.45-0.55 eq / 100g.

[0011] Preferably, the curing agent is prepared by a method comprising the following steps: B1. mixing four-arm vinyl POSS with polyetheramine D400 and refluxing in a solvent; B2. after the refluxing reaction is completed, adding a quaternizing agent to perform quaternization modification, thereby obtaining the curing agent.

[0012] Preferably, in step B1, the molar ratio of vinyl groups in the four-arm vinyl POSS to amino groups in the polyetheramine D400 is 1:(5-8); the reflux reaction temperature is 60-80℃, and the reaction time is 24-48h; the solvent is toluene; in step B2, the quaternization modification temperature is 60-80℃, the quaternization modification time is 6-12h, and the degree of quaternization is 30%-50%.

[0013] Preferably, in step B2, the quaternizing agent includes hexadecane bromide and tetrabutylammonium bromide, the molar amount of hexadecane bromide is 30%-50% of the total molar amount of amino groups in polyetheramine D400, and the amount of tetrabutylammonium bromide is 0.5wt%-1.5wt% of the total mass of the addition product of tetra-arm vinyl POSS and polyetheramine D400 and hexadecane bromide.

[0014] Preferably, the accelerator is an esterification product of perfluoropolyether alcohol and maleic anhydride, with a degree of esterification ≥90%, a molecular weight of 2000-5000 Da, and an HLB value of 4-6.

[0015] Preferably, the hydrophobic agent further comprises self-healing microcapsules, wherein the amount of the self-healing microcapsules is 5-15 parts.

[0016] Preferably, the weight ratio of the hardener to the hydrophobic agent is 1:(0.5-1.4).

[0017] More preferably, the self-healing microcapsules are prepared by a method comprising the following steps: C1. mixing and emulsifying thiol-terminated polysulfide rubber with nano-montmorillonite; C2. coating with ethyl cellulose as the wall material by interfacial polymerization to obtain the self-healing microcapsules.

[0018] Preferably, in step C1, the mass ratio of the thiol-terminated polysulfide rubber to the nano-montmorillonite is 1:(1.5-2.5); in step C2, the pH of the interfacial polymerization reaction is 4.5-5.5.

[0019] Preferably, in step C1, the emulsification is carried out using a homogenizer with a rotation speed of 10,000-15,000 rpm; the SH content of the thiol-terminated polysulfide rubber is 2.5-3.5 mmol / g, and the thickness of the nano-montmorillonite sheets is 1-3 nm.

[0020] More preferably, the self-healing microcapsules have an average particle size of 80-150 μm, a wall thickness of 10-20 μm, and a core material content of ≥85%.

[0021] The present invention also provides a method for preparing an underwater concrete self-healing material containing dynamic disulfide bonds, which adopts the following technical solution: The method for preparing an underwater concrete self-healing material containing dynamic disulfide bonds as described above includes the following steps: (1) heating the epoxy prepolymer containing dynamic disulfide bonds to 40-50°C, adding a curing agent and stirring; (2) adding the accelerator, ultrasonically dispersing, and obtaining a mixture; (3) degassing the mixture and injecting it into a mold, and curing it in a seawater environment.

[0022] Preferably, step (2) further includes the step of adding the self-healing microcapsules.

[0023] More preferably, in step (1), after adding the curing agent, the stirring speed is 800-1200 rpm and the stirring time is 10-20 min; in step (2), the ultrasonic frequency is 40 kHz, the ultrasonic power is 0.5-1.0 W / cm³, and the ultrasonic time is 30-60 min; in step (3), the seawater temperature is 5-35℃, the flow rate is ≤1.5 m / s, and the curing time is 24-48 h.

[0024] This invention also provides the application of underwater concrete self-healing materials containing dynamic disulfide bonds, which adopts the following technical solution: the application of underwater concrete self-healing materials containing dynamic disulfide bonds as described above in the repair of concrete matrix in seawater.

[0025] Preferably, when the underwater concrete self-healing material containing dynamic disulfide bonds is applied to the repair of concrete substrates in seawater, the amount of the underwater concrete self-healing material containing dynamic disulfide bonds per square meter of concrete surface is ≥500g.

[0026] More preferably, the thickness of the repair layer is 3-10 mm.

[0027] Beneficial effects:

[0028] The underwater concrete self-healing material containing dynamic disulfide bonds of the present invention uses an epoxy prepolymer containing dynamic disulfide bonds as the main network. When it breaks under external force, it can then spontaneously recombine to form new covalent bonds, thereby repairing microcracks.

[0029] The curing agent in the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention is an environmentally responsive curing agent. It adopts a star-shaped topological structure design and is endowed with directional migration ability in the seawater environment through quaternization modification, which significantly enhances the interfacial bonding strength with the concrete matrix. After 200 dry and wet cycles, the bond strength retention rate is >85%.

[0030] The dual repair mechanism of the self-healing microcapsules and the epoxy prepolymer containing dynamic disulfide bonds in the underwater concrete self-healing material of the present invention can achieve a self-healing efficiency of over 90% for cracks with a width ≤200μm, which greatly improves the durability of marine engineering structures.

[0031] The underwater concrete self-healing material containing dynamic disulfide bonds of this invention is a gradient curing system. It can complete curing in seawater at 5-35℃ for 24-48 hours, with a curing degree of over 92%, far exceeding the level of existing technologies and meeting the rapid repair needs of marine engineering. The gradient curing system refers to the structural system in which the underwater concrete self-healing material containing dynamic disulfide bonds of this invention forms a gradually changing curing degree from the surface to the interior in a seawater environment. Specifically, when the repair material is applied to the surface of underwater concrete, due to the special design of the curing agent (quaternized ammonium modified four-arm POSS structure), it preferentially migrates and completes curing at the seawater interface. This preferential curing forms a protective layer, under which the internal components gradually complete curing, thus forming a gradient structure with decreasing curing degree from the outside to the inside. This gradient structure is beneficial for the interfacial bonding between the material and the concrete matrix, and can more effectively block the penetration of chloride ions in seawater.

[0032] The underwater concrete self-healing material containing dynamic disulfide bonds of this invention has excellent chloride ion barrier capabilities, with a chloride ion diffusion coefficient ≤2.5×10⁻⁶. -12 With a capacity of m² / s, which is 1 / 40th of existing materials, it can effectively prevent chloride ions in seawater from corroding reinforced concrete structures and extend the service life of engineering structures.

[0033] The underwater concrete self-healing material containing dynamic disulfide bonds of this invention is suitable for intelligent repair and long-term protection of concrete structures in harsh marine environments such as cross-sea bridge piers and deep-sea drilling platforms, providing an innovative solution for infrastructure maintenance in tidal zones and splash zones. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0035] The present invention will now be described in detail with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0036] This invention addresses at least one of the problems of current concrete repair materials, namely, difficulty in rapid curing in seawater environments, poor self-healing ability, and difficulty in resisting chloride ion penetration over a long period of time, by providing an underwater concrete self-healing material containing dynamic disulfide bonds.

[0037] The underwater concrete self-healing material containing dynamic disulfide bonds of this invention comprises, by weight, the following components: a hardener, which is 50-70 parts (e.g., 50, 55, 60, 65, or 70 parts) of an epoxy prepolymer containing dynamic disulfide bonds; and a hydrophobic agent, comprising 20-35 parts (e.g., 20, 25, 30, or 35 parts) of a curing agent and 1-3 parts (e.g., 1, 1.5, 2, 2.5, or 3 parts) of an accelerator. If the amount of hardener is too large (ratio exceeding 1:0.5), it will lead to: 1) insufficient cross-linking network density, reduced curing degree, and incomplete curing of the repair material in the seawater environment; 2) decreased material mechanical strength and weakened bond strength to the concrete matrix; 3) reduced self-healing efficiency because the dynamic disulfide bond density is insufficient to form an effective self-healing network; and 4) decreased chloride ion barrier performance and increased chloride ion diffusion coefficient. If the amount of hardener is too small (ratio below 1:1.4), it will lead to: 1) excessively dense cross-linked network, making the material brittle and reducing its impact resistance; 2) increased internal stress, making it prone to shrinkage cracks during curing; 3) poor fluidity during underwater construction, making it difficult to completely wet the concrete surface; 4) excessive hardener may cause local overheating, which will affect the overall performance of the material. Through experimental verification, the 1:(0.5-1.4) mixing ratio range determined in this invention can balance the above factors and achieve the best results in terms of material curing degree, bond strength, self-healing efficiency, and chloride ion barrier performance.

[0038] The underwater concrete self-healing material containing dynamic disulfide bonds of the present invention uses an epoxy prepolymer containing dynamic disulfide bonds as the main network. After the dynamic disulfide bonds break under external force, they can spontaneously recombine to form new covalent bonds, thus repairing microcracks.

[0039] The underwater concrete self-healing material containing dynamic disulfide bonds of this invention provides new ideas and technologies for the long-term repair and protection of marine engineering structures, and can promote the development of marine engineering materials. It has important theoretical significance and significant engineering application value, and has a very broad market prospect.

[0040] In a preferred embodiment of the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention, the epoxy prepolymer containing dynamic disulfide bonds is prepared by a method comprising the following steps: A1. Mixing 4,4'-diaminodiphenyl disulfide with bisphenol A type epoxy resin and reacting under nitrogen protection to obtain a first intermediate product; A2. Adding 1,4-butanediol diglycidyl ether to extend the chain of the first intermediate product to obtain a second intermediate product; A3. Precipitating and purifying the second intermediate product to obtain the epoxy prepolymer containing dynamic disulfide bonds.

[0041] In a preferred embodiment of the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention, in step A1, the molar ratio of 4,4'-diaminodiphenyl disulfide to bisphenol A type epoxy resin is 1:(2-3) (e.g., 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, or 1:3); the reaction temperature is 80-100℃ (e.g., 80℃, 85℃, 90℃, 95℃, or 100℃); and the reaction time is 4-6 h (e.g., 4 h, 4.5 h). h, 5h, 5.5h or 6h); in step A2, the chain extension degree is controlled at 10%-15% (e.g., 10%, 11%, 12%, 13%, 14% or 15%); in step A3, the epoxy value of the epoxy prepolymer containing dynamic disulfide bonds is 0.25-0.35eq / 100g (e.g., 0.25eq / 100g, 0.28eq / 100g, 0.3eq / 100g, 0.32eq / 100g or 0.35eq / 100g). If the amount of 4,4'-diaminodiphenyl disulfide in step A1 is too large (molar ratio < 1:2): it will lead to an excessively high density of dynamic disulfide bonds in the molecular chain, making the material overly sensitive and causing unexpected breakage and recombination under normal service conditions; the molecular weight distribution of the prepolymer will become wider, affecting processing performance and curing uniformity; excessive amino groups will react excessively with epoxy groups, resulting in the epoxy value of the prepolymer being lower than the design value, affecting subsequent curing reactions; the mechanical strength of the self-healing material will decrease, and its hydrolytic stability will deteriorate. If the amount of 4,4'-diaminodiphenyl disulfide is too small (molar ratio > 1:3): the density of dynamic disulfide bonds will be insufficient, the self-healing efficiency will be significantly reduced, and the self-healing requirements of cracks will not be met; the lack of sufficient flexible units in the molecular chain structure will lead to insufficient toughness and decreased impact resistance; the epoxy value will be too high, increasing internal stress during curing and easily causing shrinkage cracks; localized insufficient curing may occur during the curing process in a seawater environment.

[0042] If the chain extension is too large (>15%) in step A2: the viscosity of the epoxy prepolymer increases significantly, resulting in poor mixing uniformity with the curing agent and affecting the fluidity for underwater construction; the prepolymer molecular weight is too large, increasing the possibility of molecular chain entanglement and affecting the breaking-reorganization efficiency of dynamic disulfide bonds; it reduces the epoxy functionality, decreases the curing reactivity, and makes it difficult to achieve rapid curing in seawater environments; the free volume in the network structure after curing decreases, leading to increased material rigidity and decreased toughness. If the chain extension is too small (<10%): the prepolymer molecular weight is insufficient, resulting in low cured network density and decreased mechanical properties; the density of active epoxy groups in the material is too high, resulting in excessive heat release during the curing process, which may lead to local overheating damage; the network structure lacks sufficient flexible segments, causing the material to generate large internal stress under temperature fluctuations; it affects the interfacial compatibility with the concrete matrix, reducing bond strength and durability.

[0043] If the epoxy value of the epoxy prepolymer containing dynamic disulfide bonds is too high (>0.35eq / 100g): excessive exothermic curing reaction, especially in large-volume repairs, may lead to excessively high internal temperatures and cracks; increased curing shrinkage rate, making stress concentration more likely at the bonding interface with the concrete matrix; reduced relative content of dynamic disulfide bonds in the molecular chain, weakening self-healing ability; excessive cross-linking of the network structure, making the material brittle and reducing fatigue resistance. If the epoxy value of the epoxy prepolymer containing dynamic disulfide bonds is too low (<0.25eq / 100g): insufficient cross-linking points, resulting in an incomplete cured network structure, reduced material strength and durability; slow curing rate in seawater environment, making it difficult to meet the needs of rapid engineering repairs; insufficient degree of curing, easily affected by long-term seawater immersion, leading to material performance degradation; reduced chloride ion barrier properties, unable to effectively protect the steel reinforcement inside the concrete from corrosion.

[0044] Preferably, in step A1, the epoxy value of the bisphenol A type epoxy resin is 0.45-0.55 eq / 100g (e.g., 0.45 eq / 100g, 0.48 eq / 100g, 0.5 eq / 100g, 0.52 eq / 100g or 0.55 eq / 100g).

[0045] In a preferred embodiment of the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention, the curing agent is prepared by a method comprising the following steps: B1. Mixing tetra-arm vinyl POSS with polyetheramine D400 and refluxing in a solvent; B2. After the refluxing reaction is completed, adding a quaternizing agent to perform quaternization modification, thereby obtaining the curing agent. The four-arm vinyl POSS plays several key roles: 1) As a core framework, the POSS molecule possesses a rigid cage-like structure, providing a stable three-dimensional framework for the curing agent and forming the basis for a star-shaped topology; 2) Providing reaction sites: The vinyl functional groups on the four-arm vinyl POSS are active sites for addition reactions with polyetheramine D400, ensuring the synthesis pathway of the curing agent; 3) Enhancing interfacial compatibility: The dual characteristics of the inorganic siloxane core and organic substituents of POSS endow the curing agent with good interfacial compatibility with the concrete matrix, enhancing the bonding strength; 4) Improving durability: The POSS structure improves the thermal stability and hydrolysis resistance of the curing agent, enabling the repair material to have a longer service life in seawater environments; 5) Promoting micelle formation: The rigid structure of the POSS core, after quaternization, facilitates the formation of a stable micelle structure in seawater by the curing agent, enhancing its directional migration ability.

[0046] If the quaternization modification step in step B2 is omitted, the following serious adverse effects will occur: the curing agent loses its amphiphilic structure, cannot form micelles in seawater, and its directional migration ability is greatly reduced; the curing rate in the seawater environment is significantly slowed down, the degree of curing is insufficient, and it is difficult to meet the needs of rapid engineering repair; the interfacial bonding strength with the concrete matrix is ​​reduced, and the bond strength retention rate drops from more than 85% to less than 50% after wet and dry cycles; the chloride ion barrier efficiency is severely reduced, the chloride ion diffusion coefficient increases by 10-20 times, and it loses its ability to protect the internal steel reinforcement of the concrete; the durability in the seawater environment is greatly reduced, and the service life is shortened to less than 1 / 3 of the original design life.

[0047] The curing agent of this invention adopts a star-shaped topology design and is endowed with directional migration ability in seawater environment through quaternization modification. It can automatically form micelle structure in seawater environment (that is, the curing agent of this invention is more suitable for seawater environment than pure water; this is mainly due to the star-shaped topology and quaternization modification design of the curing agent, which makes it produce a specific response to the high salinity environment in seawater). Underwater directional migration is regulated by interfacial free energy, and anchoring is preferentially completed at the pores of concrete, which significantly enhances the interfacial bonding strength with the concrete matrix (bond strength retention rate >85% after 200 dry and wet cycles).

[0048] In a preferred embodiment of the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention, in step B1, the molar ratio of the vinyl group in the four-arm vinyl POSS to the amino group in the polyetheramine D400 is 1:(5-8) (e.g., 1:5, 1:6, 1:7 or 1:8); the reflux reaction temperature is 60-80°C (e.g., 60°C, 65°C, 70°C, 75°C or 80°C); and the reaction time is 24-48 h (e.g., 24 h). The solvent is toluene; in step B2, the quaternization modification temperature is 60-80℃ (e.g., 60℃, 65℃, 70℃, 75℃ or 80℃), the quaternization modification time is 6-12h (e.g., 6h, 7h, 8h, 9h, 10h, 11h or 12h), and the degree of quaternization is 30%-50% (e.g., 30%, 35%, 40%, 45% or 50%). In step B1, the tetravinyl group in the four-arm vinyl POSS is designed with a high excess ratio of amine groups to polyetheramine D400 (in conventional POSS modification reactions, the molar ratio of vinyl to amine groups is usually 1:1-1:3). This helps ensure that each vinyl group on the POSS reacts fully to form a complete star structure; it also retains enough free amine groups after the reaction for epoxy curing and subsequent quaternization modification; it reduces the possibility of intermolecular crosslinking, avoids gel formation, and improves the solubility and processability of the product. A lower reaction temperature (commonly 90-120℃) is used in step B1 to help suppress the thermal oxidative degradation of polyetheramine, maintain the integrity of the molecular structure, improve the selectivity of the addition reaction, reduce side reactions, and reduce the energy consumption of the reaction system, which is more in line with the concept of green chemistry. An extended reaction time (commonly 6-12 hours) is used in step B1 to help ensure the completeness of the reaction under lower temperature conditions; it allows the four vinyl groups on the POSS core to react uniformly, forming a structurally symmetrical product; and it is beneficial for a narrower molecular weight distribution and more stable performance of the product. The parameter combination in step B1 optimizes the molecular structure of the curing agent, enabling it to form an ideal micelle structure in the seawater environment after subsequent quaternization, thereby improving the material's performance in the underwater environment.

[0049] Traditional quaternization reactions typically proceed at 80-100°C for 2-4 hours, or at room temperature for 24-72 hours. The moderate reaction temperature (60-80°C) in step B2 balances reaction rate and selectivity, avoiding side reactions and degradation caused by high temperatures; protects the integrity of the POSS core structure, maintaining its rigidity; and promotes uniform quaternization, avoiding localized over-reaction. The precisely controlled reaction time (6-12 hours) in step B2 achieves a moderate degree of quaternization (30-50%), maintaining the balance of the amphiphilicity of the molecules; too short a time leads to insufficient quaternization, affecting responsiveness in seawater environments; too long a time leads to over-quaternization, disrupting the hydrophilic-hydrophobic balance of the molecular design; and provides optimal viscosity and flowability for the curing agent, suitable for underwater application. The unique catalytic system design in step B2—the addition of tetrabutylammonium bromide as a phase transfer catalyst—significantly improves reaction efficiency; allows the reaction to achieve the ideal degree of quaternization under mild conditions; reduces energy consumption; and improves the economics of the product. The above parameter combination was obtained through extensive experimental optimization. Compared with the traditional quaternization reaction process, it can more accurately control the structural characteristics of the curing agent, ensuring that it forms an ideal micelle structure in the seawater environment, and achieving directional migration and efficient curing of the concrete surface.

[0050] If the degree of quaternization is too low (<30%): the curing agent molecules lack sufficient amphiphilic characteristics, making it difficult to form a stable micelle structure in a seawater environment; the directional migration ability is significantly reduced, failing to effectively migrate and anchor to the concrete matrix interface; the interfacial bonding force with the concrete matrix is ​​insufficient, especially under wet-dry cycling conditions, the bond strength decays rapidly; the electrostatic response to chloride ions in seawater is insufficient, slowing down the curing rate and reducing the degree of curing; the chloride ion barrier performance of the formed curing network decreases, making it difficult to effectively protect the steel reinforcement inside the concrete. If the degree of quaternization is too high (>50%): excessive quaternary ammonium salt groups lead to excessive hydrophilicity of the curing agent molecules, reducing compatibility with epoxy prepolymers; phase separation is easily formed in the mixed system, affecting the uniformity of the material and the curing quality; excessively high charge density leads to increased molecular chain rigidity, reducing the toughness of the curing network; excessive water absorption and swelling in a seawater environment leads to poor material volume stability and decreased long-term service performance; excessive quaternary ammonium salt groups compete with the epoxy curing reaction, interfering with the normal curing reaction and reducing the degree of crosslinking.

[0051] Preferably, in step B2, the quaternizing agents are hexadecane bromide and tetrabutylammonium bromide. The molar amount of hexadecane bromide is 30%-50% of the total molar amount of amino groups in polyetheramine D400, and the amount of tetrabutylammonium bromide is 0.5wt%-1.5wt% (e.g., 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, or 1.5wt%) of the total mass of the addition product of tetra-arm vinyl POSS and polyetheramine D400 and hexadecane bromide. The role of hexadecane bromide as the main quaternizing agent is to: provide a hydrophobic carbon chain of appropriate length, enabling the curing agent to form an amphiphilic structure, which is beneficial for the formation of micelles in seawater; the carbon chain length (C16) can balance the hydrophilicity and hydrophobicity of the quaternary ammonium salt, optimizing the directional migration ability of the curing agent at the water-concrete interface; and provide appropriate electrostatic interaction strength to ensure effective interaction with chloride ions in seawater. The role of tetrabutylammonium bromide: As a phase transfer catalyst, it promotes the smooth progress of the quaternization reaction in a two-phase system; accelerates the quaternization reaction rate and shortens the reaction time; improves the selectivity and conversion rate of the quaternization reaction; and controls the degree of quaternization, maintaining it within the optimal range of 30%-50%. The appropriate amount of hexadecane bromide helps ensure that an appropriate proportion of amine groups in the molecule are converted into quaternary ammonium salt groups, maintaining the amphiphilic balance of the curing agent and enabling it to form an ideal micelle structure in a seawater environment. The appropriate amount of tetrabutylammonium bromide effectively catalyzes the quaternization reaction, improves reaction efficiency, and avoids side reactions that may result from excessive catalyst. Specifically, the calculation method for the amount of hexadecane is as follows: If the molar ratio of vinyl to amino groups in step B1 is 1:6, about 1 / 6 of the amino groups in polyetheramine D400 participate in the addition reaction with the four-arm vinyl POSS, and the remaining 5 / 6 of the amino groups are free amino groups; the molar number of hexadecane = total amount of free amino groups × degree of quaternization (30%-50%) = 5 / 6 of the total amount of amino groups in polyetheramine D400 × degree of quaternization (30%-50%).

[0052] In a preferred embodiment of the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention, the accelerator is an esterification product of perfluoropolyether alcohol and maleic anhydride, with an esterification degree ≥90%, a molecular weight of 2000-5000 Da, and an HLB value of 4-6. The accelerator of the present invention helps reduce interfacial tension in seawater, promotes the migration of the curing agent to the concrete matrix, and forms a chloride ion barrier. However, if the esterification degree of the accelerator is too low (<90%): excessive unreacted perfluoropolyether alcohol hydroxyl groups remain, increasing the hydrophilicity of the system and disrupting the preset hydrophobic / hydrophilic balance; reducing the compatibility between the accelerator and the epoxy system, potentially leading to phase separation and affecting mixing uniformity; weakening the interfacial tension control ability, reducing the migration efficiency of the curing agent to the concrete matrix; and resulting in an incomplete chloride ion barrier and an increased chloride ion diffusion coefficient. If the esterification degree of the accelerator is too high (>99%): more stringent reaction conditions and multiple purifications are required, significantly increasing production costs; by-reaction products may be introduced, affecting the purity and performance stability of the accelerator; performance improvement is limited in practical applications, making it uneconomical.

[0053] If the molecular weight of the accelerator is too low (<2000 Da): it has excessive volatility and fluidity, making it prone to loss in seawater environments; the chain segment length is insufficient, failing to form an effective interfacial network structure; and its compatibility with the epoxy system is reduced, potentially leading to precipitation from the system. If the molecular weight of the accelerator is too high (>5000 Da): the molecular chain is too long, increasing entanglement and reducing activity; the dispersion uniformity deteriorates, making it difficult to fully utilize the interfacial regulation function; the system viscosity increases significantly, affecting construction fluidity and concrete wettability; and the molecular chain flexibility decreases, resulting in reduced responsiveness.

[0054] If the accelerator's HLB value is too low (<4): it is too hydrophobic, making it difficult to form a stable interface in a seawater environment; it has too good compatibility with epoxy prepolymers, preventing effective migration to the interface; and it cannot promote the migration of the curing agent to the concrete matrix, thus losing its key function. If the accelerator's HLB value is too high (>6): it is too hydrophilic, causing the accelerator to preferentially interact with seawater rather than be located at the interface; it may lead to excessive water penetration into the repair material, weakening the chloride ion barrier effect; and it affects the integrity of the cured network structure, reducing the material's mechanical properties and durability.

[0055] In a preferred embodiment of the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention, the hydrophobic agent component further includes self-healing microcapsules, and the amount of self-healing microcapsules is 5-15 parts (e.g., 5 parts, 8 parts, 10 parts, 13 parts or 15 parts).

[0056] Preferably, the weight ratio of the hardener to the hydrophobic agent is 1:(0.5-1.4) (e.g., 1:0.5, 1:0.7, 1:0.9, 1:1.1, 1:1.3 or 1:1.4).

[0057] More preferably, the self-healing microcapsules are prepared by a method including the following steps: C1. Mixing and emulsifying thiol-terminated polysulfide rubber with nano-montmorillonite; C2. Encapsulating the microcapsules with ethyl cellulose as the wall material using interfacial polymerization, thus obtaining the self-healing microcapsules. The nano-montmorillonite plays the following roles: 1) Synergistic repair and enhancement: Nano-montmorillonite and thiol-terminated polysulfide rubber form a composite repair system. When the microcapsules rupture and release their contents, the montmorillonite nanosheets can form a physical barrier on the crack surface, while the thiol groups react chemically with the dynamic disulfide bonds in the epoxy matrix, achieving a physicochemical synergistic repair mechanism; 2) Enhanced space-filling capacity: The nanosheet structure of montmorillonite (sheet thickness 1-3 nm) has a high specific surface area, which can more effectively fill crack spaces, especially for narrower microcracks (<100 μm), where the filling efficiency is significantly higher than that of a single component; 3) Improved environmental stability: Nano-montmorillonite can form an intercalation composite with thiol-terminated polysulfide rubber. The nano-montmorillonite exhibits several key advantages: 1) Enhanced stability of the repair agent in seawater environments, slowing hydrolytic degradation and extending effective repair time; 2) Improved rheological properties: The nano-montmorillonite modulates the rheological properties of the repair agent, ensuring appropriate fluidity after release and allowing for full penetration into cracks; it also provides thixotropy during curing to prevent loss of the repair agent from cracks; 3) Enhanced barrier properties: The layered structure of the nano-montmorillonite creates a "maze effect" during the repair process, significantly improving the barrier properties of the repaired area against chloride ions, extending the chloride ion diffusion path by 3-5 times; 4) Catalytic effect: The active sites on the surface of the nano-montmorillonite catalyze the reaction between thiols and epoxy groups, accelerating the curing process of the repair agent in humid environments. By optimizing the ratio of nano-montmorillonite to thiol-terminated polysulfide rubber at a 1:2 mass ratio, the nano-montmorillonite can fully exert the above effects, achieving highly efficient self-repair of cracks (repair efficiency ≥90%), while providing long-lasting chloride ion barrier protection, making it a key component of the self-repairing microcapsule system of this invention.

[0058] The introduction of self-healing capsules in this invention allows the microcapsules to rupture when a crack expands to a certain width, releasing a repair agent that forms a new cross-linked network and physical barrier at the crack, jointly inhibiting further crack expansion. Specifically, the self-healing microcapsules of this invention rupture when the crack expands, releasing a mixture of thiol-terminated polysulfide rubber and nano-montmorillonite as a repair agent, forming a dual physical and chemical repair mechanism.

[0059] In a preferred embodiment of the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention, in step C1, the mass ratio of thiol-terminated polysulfide rubber to nano-montmorillonite is 1:(1.5-2.5) (e.g., 1:1.5, 1:2, or 1:2.5); in step C2, the pH of the interfacial polymerization reaction is 4.5-5.5 (e.g., 4.5, 4.8, 5, 5.3, or 5.5). However, if the proportion of thiol-terminated polysulfide rubber is too high (mass ratio > 1:1.5): the repair agent viscosity is too high, resulting in insufficient fluidity after microcapsule rupture and difficulty in fully penetrating the cracks; there are too many SH functional groups, leading to an excessively fast curing rate, causing curing to begin before sufficient penetration into the cracks; compatibility with epoxy materials decreases, affecting interfacial bonding strength; the repaired area lacks sufficient "maze effect," significantly reducing chloride ion barrier performance. If the proportion of thiol-terminated polysulfide rubber is too low (mass ratio <1:2.5): the concentration of active SH functional groups is insufficient, and the cross-linking reaction with epoxy substances is incomplete; the repair efficiency is reduced, especially the ability to repair cracks with a width >100μm is significantly insufficient; the proportion of montmorillonite is too high, which leads to a decrease in dispersibility, the formation of agglomerates, and a reduction in repair uniformity; the repaired area becomes brittle, and the fatigue resistance decreases.

[0060] Preferably, in step C1, emulsification is performed using a homogenizer with a rotation speed of 10,000-15,000 rpm (e.g., 10,000 rpm, 11,000 rpm, 12,000 rpm, 13,000 rpm, 14,000 rpm, or 15,000 rpm); the SH content of the thiol-terminated polysulfide rubber is 2.5-3.5 mmol / g (e.g., 2.5 mmol / g, 2.7 mmol / g, 2.9 mmol / g, 3.2 mmol / g, or 3.5 mmol / g); and the thickness of the nano-montmorillonite sheets is 1-3 nm (e.g., 1 nm, 2 nm, or 3 nm).

[0061] More preferably, the self-healing microcapsules have an average particle size of 80-150 μm (e.g., 80 μm, 100 μm, 120 μm, 140 μm, or 150 μm), a wall thickness of 10-20 μm (e.g., 10 μm, 13 μm, 16 μm, 18 μm, or 20 μm), and a core material content ≥85%. The selection of the particle size of the self-healing microcapsules is based on the following criteria: 1) Particle size: The particle size must be larger than the average width of the microcracks on the concrete surface (typically 50-100 μm) to ensure sufficient release of repair agent after rupture; too small a particle size (<80 μm) results in insufficient core material content, and the released repair agent is insufficient to fill the cracks; too large a particle size (>150 μm) is prone to premature rupture due to shear force during construction and affects material uniformity; a particle size range of 80-150 μm matches the average particle spacing of the epoxy material to ensure uniform distribution and effective coverage. 2) Wall thickness: It needs to be sufficiently robust to maintain integrity during processing such as stirring and ultrasonic dispersion; a wall thickness that is too thin (<10μm) is not stable enough in a seawater environment and is prone to leakage; a wall thickness that is too thick (>20μm) reduces the core material content and increases the external force required for rupture, which may affect the sensitivity of repair triggering; a wall thickness of 10-20μm provides an ideal balance between mechanical strength and rupture sensitivity. 3) Core material content: A high core material content ensures sufficient repair dosage, and a single rupture can completely fill the crack; a content that is too low (<85%) cannot provide enough repair agent, resulting in incomplete repair; a content that is too high (>95%) is difficult to achieve through conventional interfacial polymerization methods, or results in insufficient capsule wall strength; a content of ≥85% achieves the best balance between repair efficiency and preparation feasibility.

[0062] The present invention also proposes a method for preparing an underwater concrete self-healing material containing dynamic disulfide bonds. The method for preparing the underwater concrete self-healing material containing dynamic disulfide bonds according to the present invention includes the following steps: (1) heating the epoxy prepolymer containing dynamic disulfide bonds to 40-50℃ (e.g., 40℃, 42℃, 44℃, 46℃, 48℃ or 50℃), adding a curing agent and stirring; (2) adding an accelerator, ultrasonically dispersing, and obtaining a mixture; (3) degassing the mixture and injecting it into a mold, and curing it in a seawater environment.

[0063] In a preferred embodiment of the preparation method of the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention, step (2) further includes the step of adding self-healing microcapsules.

[0064] In a preferred embodiment of the preparation method of the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention, in step (1), after adding the curing agent, the stirring speed is 800-1200 rpm (e.g., 800 rpm, 900 rpm, 1000 rpm, 1100 rpm or 1200 rpm), and the stirring time is 10-20 min (e.g., 10 min, 15 min or 20 min); in step (2), the ultrasonic frequency is 40 kHz, the ultrasonic power is 0.5-1.0 W / cm³ (e.g., 0.5 W / cm³, 0.6 W / cm³, 0.7 W / cm³, 0.8 W / cm³, 0.9 W / cm³ or 1.0 W / cm³), and the ultrasonic time is 30-60 min (e.g., 30 min, 40 min, 50 min or 60 min). The stirring speed and time in step (1) have a direct impact on the material properties. Precise control of stirring speed and time is necessary to achieve the following key effects: promote the pre-reaction between the epoxy prepolymer containing dynamic disulfide bonds and the curing agent to form an appropriate initial cross-linking network structure; activate the quaternary ammonium salt groups in the curing agent molecules to improve their responsiveness in subsequent seawater environments; and control the viscosity changes of the system to ensure that the mixture has optimal subsequent processing performance.

[0065] In step (2), the main functions of ultrasonic treatment are: 1) Ultrasonic treatment is crucial for the dispersion of self-healing microcapsules: it breaks up microcapsule aggregates through sound wave energy to achieve a monodisperse state; it promotes the uniform distribution of self-healing microcapsules in epoxy materials to ensure spatial consistency of repair efficiency; it controls the interfacial bonding state between the surface of self-healing microcapsules and epoxy materials so that they can rupture accurately when cracks form; 2) Ultrasonic parameters have an important influence on the mechanism of action of migration promoters: appropriate ultrasonic energy activates migration promoter molecules and enhances their directional distribution ability at the interface; it promotes the formation of specific interactions between migration promoters and epoxy prepolymers containing dynamic disulfide bonds, thereby improving interfacial activity in the seawater environment; 3) Ultrasonic parameters directly affect material properties: the frequency (40kHz) is optimized to effectively disperse components without damaging the microcapsule structure; the power (0.5-1.0W / cm³) is controlled within the range that can effectively disperse components without causing degradation; the time (30-60min) needs to be precisely controlled to ensure sufficient dispersion without excessively damaging the microcapsule wall structure.

[0066] In a preferred embodiment of the preparation method of the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention, in step (3), the temperature of the seawater is 5-35℃ (e.g., 5℃, 10℃, 15℃, 20℃, 25℃, 30℃ or 35℃), the flow rate is ≤1.5m / s, and the curing time is 24-48h (e.g., 24h, 30h, 36h, 42h or 48h). Here, 5-35℃ refers to the optimal performance operating range of the underwater concrete self-healing material containing dynamic disulfide bonds of the present invention, rather than an absolute usage limitation. The underwater concrete self-healing material containing dynamic disulfide bonds of the present invention has excellent temperature adaptability: in environments below 5℃, the material can still cure, but the curing time will be correspondingly extended (may require 72-96 hours), and the degree of curing will be slightly reduced but still reach over 85%, which is sufficient to meet engineering requirements; in environments above 35℃, the material curing speed is accelerated, and the amount of material applied at one time needs to be controlled to avoid excessive heat release, but this will not have a significant negative impact on the final performance. This broad temperature adaptability is a significant advantage of this invention, enabling its application in both cold winters and hot summers, meeting the all-weather maintenance needs of marine engineering. In practical engineering applications, the performance at specific temperatures can be further optimized by fine-tuning the component ratios (such as slightly increasing the proportion of curing agent in low-temperature environments), further expanding the material's practical application temperature range.

[0067] This invention also proposes the application of an underwater concrete self-healing material containing dynamic disulfide bonds, and the application of the underwater concrete self-healing material containing dynamic disulfide bonds in the repair of concrete matrix in seawater according to embodiments of this invention.

[0068] Preferably, when underwater self-healing materials containing dynamic disulfide bonds are applied to the repair of concrete substrates in seawater, the amount of underwater self-healing materials containing dynamic disulfide bonds per square meter of concrete surface is ≥500g.

[0069] More preferably, the thickness of the repair layer is 3-10 mm (e.g., 3 mm, 5 mm, 7 mm, 9 mm, or 10 mm). If the repair layer thickness is too small (<3 mm), the following adverse effects will occur: 1) The protective layer is too thin, failing to provide sufficient chloride ion penetration path length, significantly reducing the chloride ion blocking effect; 2) Insufficient number of self-healing microcapsules, meaning that when cracks form, not enough microcapsules may be destroyed to release the repair agent; 3) Reduced resistance to seawater erosion and mechanical wear, shortening service life; 4) Insufficient coverage of uneven areas on the concrete substrate surface, creating protective dead zones and leading to localized repair failure; 5) Difficulty in forming a complete protective barrier, especially in harsh environments such as tidal zones and splash zones. If the repair layer is too thick (>10mm), the following adverse effects will occur: 1) Increased heat release during curing, which can easily generate internal thermal stress and lead to the formation of microcracks; 2) Increased shrinkage stress during curing of thick layers, which affects the interfacial bonding strength with the concrete matrix; 3) Significantly increased material consumption, which increases project costs and reduces economic efficiency; 4) Extended curing time, especially the time required for complete internal curing; The increased self-weight of excessively thick materials can easily cause sagging on vertical or inclined surfaces, affecting construction quality.

[0070] The following detailed description of the underwater concrete self-healing material containing dynamic disulfide bonds, its preparation method, and its application are illustrated by specific embodiments of the present invention.

[0071] The sources of the main raw materials used in the following examples:

[0072] (1) 4,4'-Diaminodiphenyl disulfide: purchased from Aladdin Reagent (Shanghai) Co., Ltd., purity ≥98%, product number B107366; (2) Bisphenol A type epoxy resin: DER™332 epoxy resin produced by DOW Chemical, epoxy value 0.50eq / 100g, viscosity 4000-6000mPa·s (25℃); (3) 1,4-Butanediol diglycidyl ether: purchased from Bailingwei Technology Co., Ltd., purity ≥99%, product number J62701; (4) Tetra-arm vinyl POSS: purchased from Hangzhou Jingrui Chemical Co., Ltd., purity ≥98%, product model JR-VPOSS4, vinyl content 4.2-4.5 mmol / g; (5) Polyetheramine D400: JEFFAMINE® D-400 produced by Huntsman Corporation, with an average molecular weight of about 400 and an amine value of 230-260 mgKOH / g; (6) Bromohexadecane: purchased from Bailingwei Technology Co., Ltd., purity ≥98%, product number B0281; (7) Tetrabutylammonium bromide: purchased from Maclean Biotechnology Co., Ltd., purity ≥99%, product number T818283; (8) Thiol-terminated polysulfide rubber: LP-3 type polysulfide rubber produced by Shenyang Chemical Research Institute Co., Ltd., which is thiol-terminated. End-capping treatment, SH content 3.0 mmol / g; Thiol end-capping treatment method: LP-3 type polysulfide rubber and mercaptoethanol are mixed in a 1:2 molar ratio in tetrahydrofuran solvent, triethylamine catalyst is added, and the reaction is carried out at 60℃ for 4 hours, and then purified; (9) Nano montmorillonite: SF-MT1000 type nano montmorillonite produced by Nanjing Xianfeng Nanomaterials Technology Co., Ltd. is used, with a sheet thickness of 1-3 nm, a specific surface area of ​​700-800 m² / g, and a cation exchange capacity of 80-90 meq / 100g; (10) Ethyl cellulose: purchased from Aladdin Reagent (Shanghai) Co., Ltd., with a viscosity of 45-55 mPa·s (5% i n80:20 toluene / ethanol, 25℃), ethoxy content 48-49.5%; (11) Perfluorinated polyether alcohol: DEMNUM series products produced by Daikin Industries, Ltd., with an average molecular weight of 3000 Da and a hydroxyl value of 37-39 mgKOH / g; (12) Maleic anhydride: purchased from Aladdin Reagent (Shanghai) Co., Ltd., with a purity ≥99%, product number M112542; (13) Conventional solvents such as toluene and acetone were purchased from Sinopharm Chemical Reagent Co., Ltd., analytical grade; (14) The seawater used in the experiment was artificially prepared standard seawater, configured according to ASTM D1141-98 standard, containing NaCl. 24.53g / L, MgCl2 5.20g / L, Na2SO4 4.09g / L, CaCl2 1.16g / L, KCl 0.695g / L, NaHCO3 0.201g / L, KBr 0.101g / L, H3BO3 0.027g / L, SrCl2 0.025g / L, NaF0.0.003 g / L, pH value 8.2 ± 0.1.

[0073] Example 1

[0074] The underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment comprises the following components by weight: 60 parts of epoxy prepolymer containing dynamic disulfide bonds, 25 parts of curing agent, 10 parts of self-healing microcapsules, and 2 parts of accelerator.

[0075] The epoxy prepolymer containing dynamic disulfide bonds was prepared using a method comprising the following steps:

[0076] A1. Mix 4,4'-diaminodiphenyl disulfide and bisphenol A type epoxy resin (epoxy value 0.50 eq / 100g) in a four-necked flask at a molar ratio of 1:2.5, purge with nitrogen, and react with mechanical stirring at 90°C for 5 hours; A2. Then add 1,4-butanediol diglycidyl ether for chain extension (at 90°C, slowly add 1,4-butanediol diglycidyl ether dropwise for chain extension, the addition time is about 30-45 minutes; after the addition is completed, continue the reaction at 90°C for 2-3 hours; the entire chain extension process is still under nitrogen). The reaction was carried out under protective atmosphere (the chain extension degree was controlled at 12%). During the experiment, the chain extension degree was monitored by sampling in real time. The monitoring method was as follows: every 30 minutes, a small sample was taken from the reaction system, and the change in molecular weight was determined by gel permeation chromatography. The chain extension reaction process was monitored by combining the epoxy value titration test. When the target chain extension degree was reached, the reaction system was quickly cooled to below 50°C to terminate the chain extension reaction. The chain extension degree (%) = [(Mn-Mn0) / Mn0] × 100%, where Mn is the current molecular weight and Mn0 is the initial molecular weight before chain extension.

[0077] A3. After the reaction was completed, the product was purified by precipitation with acetone to obtain an epoxy prepolymer containing dynamic disulfide bonds with an epoxy value of 0.30 eq / 100g.

[0078] The curing agent is prepared by a method including the following steps:

[0079] B1. Mix the four-arm vinyl POSS with polyetheramine D400 in toluene solvent at a vinyl:amine molar ratio of 1:6 and reflux at 70°C for 36 h.

[0080] B2. Subsequently, hexadecane bromide (the amount of hexadecane bromide is calculated according to the target degree of quaternization; that is, the amount of hexadecane bromide is 40% of the molar number of free amine groups in polyetheramine D400 that have not participated in the addition reaction) and tetrabutylammonium bromide catalyst (the amount of tetrabutylammonium bromide is 1.0 wt% of the total mass of the reaction product of step B1 and hexadecane bromide) are added for quaternization modification. The reaction temperature is 70℃, the reaction time is 8h, and the degree of quaternization is controlled at 40% to obtain the curing agent.

[0081] Self-healing microcapsules were prepared using a method comprising the following steps:

[0082] C1. Thiol-terminated polysulfide rubber (SH content 3.0 mmol / g) and nano-montmorillonite (sheet thickness 2 nm) were mixed and emulsified in a high-speed homogenizer (12000 rpm) at a mass ratio of 1:2 for 5 min;

[0083] C2. Then, using interfacial polymerization with ethyl cellulose as the wall material and controlling the pH value at 5.0, a coating reaction was carried out to obtain self-healing microcapsules with an average particle size of 100 μm, a wall thickness of 15 μm, and a core material content of 90%. Specifically, step C2 includes: C21. Adding 600 mL of deionized water to a 1000 mL four-necked flask, dissolving 3.0 g of polyvinyl alcohol (PVA, degree of alcoholysis 88%, phosphoric acid approximately 67,000) as an emulsifier, adding 0.5 g of sodium dodecyl sulfate (SDS) as an auxiliary emulsifier, stirring at 60 °C (400 rpm) until completely dissolved, and then cooling to room temperature; C22. Emulsification process: slowly adding the oil phase (the mixture obtained in step C1) to the aqueous phase, dispersing at a high-speed disperser (1000 rpm) for 10 minutes to form a stable O / W emulsion; C23. Preparation of the wall material solution: dissolving 6.0 g of ethyl cellulose in a mixed solvent of 60 mL cyclohexane and 20 mL dichloromethane, stirring until completely dissolved to form a wall material solution; C24. Interfacial polymerization reaction: slowly adding the wall material solution dropwise to the O / W emulsion obtained in step C22, stirring... C25. After addition, adjust the pH to 5.0 (±0.1) with dilute hydrochloric acid or a diluted aqueous solution, and react at 50°C for 3 hours. C26. Crosslinking and curing: Add 1.0 g of diethylenetriamine to the reaction system as a crosslinking agent, and continue the reaction at 50°C for 2 hours to fully crosslink and cure the wall material. C27. Post-treatment: After the reaction is complete, cool the product to the first step, collect the microcapsules by wet sieving, and wash them three times with deionized water to remove unreacted substances and surfactants. C28. Drying and sieving: Dry the collected microcapsules under vacuum at 40°C for 24 hours, and then dry sieve them through a standard sieve (80-150 μm) to collect microcapsule products that meet the particle size requirements. C29. Quality control: Measure the average particle size and wall thickness of the microcapsules using an optical microscope, and determine the core material content by thermogravimetric analysis to ensure that the microcapsules meet the design specifications.

[0084] The accelerator is the esterification product of perfluoropolyether alcohol (average molecular weight 3000 Da) and maleic anhydride, with an esterification degree of 95% and an HLB value of 5.0. The preparation method of the accelerator includes the following steps: D1. Preparation: DEMNUMS-20 perfluoropolyether alcohol (average molecular weight 3000 Da, hydroxyl value 38 mg KOH / g) produced by Daikin Industries, Ltd. is vacuum dried at 80℃ for 12 h to remove trace moisture; maleic anhydride (purity ≥99%) is purchased from Aladdin Reagent (Shanghai) Co., Ltd., and is recrystallized and purified before use; D2. Esterification reaction: 100 g of dried perfluoropolyether alcohol is added to a 250 mL three-necked flask, and nitrogen gas is introduced for protection. At 70℃, a measured amount of maleic anhydride solution (at a hydroxyl to anhydride concentration ratio of 1:1.1 molar) was added, followed by 0.5 wt% 4-dimethylaminopyridine (DMAP) as a catalyst; D3. Reaction process: Under nitrogen protection, the reaction temperature was raised to 110℃ and the reaction was stirred for 8 hours; samples were taken every 2 hours during the reaction, and the reaction progress was monitored by acid value titration; D4. Sealing treatment: After the reaction was completed, the reaction mixture was cooled to 80℃, diluted with 200 mL of dichloromethane, and then washed 3 times with 5% sodium hydroxide solution (each time...). 100 mL) to remove unreacted maleic anhydride; then wash with deionized water until neutral, and dry with anhydrous sulfuric acid; D5. Product acquisition: filter to remove desiccant, rotary evaporation to remove solvent, and finally vacuum dry at 60℃ for 24 h to obtain an accelerator product with 95% esterification degree; D6. Product characterization: confirm the completion of the esterification reaction by FTIR; determine the degree of esterification by 1H-NMR; determine the HLB value to be 5.0 by the drop ring method (a method for determining the HLB value of surfactants by measuring the diffusion behavior at the oil-water interface).

[0085] The preparation method of the underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment includes the following steps:

[0086] (1) Weigh the above components according to the ratio; heat the epoxy prepolymer containing dynamic disulfide bonds to 45°C, add the curing agent and stir at 1000 rpm for 15 min;

[0087] (2) Then add self-healing microcapsules and promoters, and ultrasonically disperse for 45 min at 40 kHz and power 0.8 W / cm³.

[0088] (3) Finally, after vacuum degassing, the material is injected into the mold (to help fix and shape the repair material on the underwater concrete surface and prevent the repair material from being lost in the seawater flow), and cured for 36 hours in a seawater environment at 20°C and a flow rate of 0.5m / s.

[0089] Example 2

[0090] The underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment differs from that in Example 1 only in the proportion of each component; all other aspects remain the same as in Example 1.

[0091] The underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment comprises the following components by weight: 50 parts of epoxy prepolymer containing dynamic disulfide bonds, 35 parts of curing agent, 15 parts of self-healing microcapsules, and 3 parts of accelerator.

[0092] Example 3

[0093] The underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment differs from that in Example 1 only in the proportion of each component; all other aspects remain the same as in Example 1.

[0094] The underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment comprises the following components by weight: 70 parts of epoxy prepolymer containing dynamic disulfide bonds, 20 parts of curing agent, 5 parts of self-healing microcapsules, and 1 part of accelerator.

[0095] Example 4

[0096] The underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment differs from that in Example 1 only in that the curing agent and self-healing microcapsules used are different from those in Example 1; all other aspects are consistent with Example 1.

[0097] Specifically: the degree of quaternization of the curing agent in this embodiment is 30%; the average particle size of the self-healing microcapsules in this embodiment is 150 μm and the wall thickness is 20 μm.

[0098] Example 5

[0099] The underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment differs from that in Example 1 only in that the HLB value of the accelerator and the curing temperature in seawater in step (3) are different from those in Example 1; all other aspects are consistent with Example 1.

[0100] Specifically: the accelerator in this embodiment has an HLB value of 4.5; in step (3) of this embodiment, curing is carried out in seawater at 10°C.

[0101] Example 6

[0102] The underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment includes the following components: 50 parts of epoxy prepolymer containing dynamic disulfide bonds, 35 parts of environmentally responsive curing agent, 15 parts of self-healing microcapsules, and 3 parts of accelerator.

[0103] The differences between this embodiment and Embodiment 1 are as follows:

[0104] (1) The preparation method of the epoxy prepolymer containing dynamic disulfide bonds in this embodiment is the same as that in Example 1, but the molar ratio of 4,4'-diaminodiphenyl disulfide to bisphenol A type epoxy resin is 1:2, and the chain extension degree is controlled to be 10%, so as to obtain an epoxy prepolymer containing dynamic disulfide bonds with an epoxy value of 0.35eq / 100g.

[0105] (2) The curing agent in this embodiment is a mixture of four-arm vinyl POSS and polyetheramine D400 in a vinyl:amine molar ratio of 1:8, and refluxed at 80°C for 48 hours; the quaternization is 30%, and other preparation conditions are the same as in Example 1.

[0106] (3) In the self-healing microcapsules of this embodiment, the SH content of thiol-terminated polysulfide rubber is 3.5 mmol / g, the average particle size is 150 μm, the wall thickness is 20 μm, and other preparation conditions are the same as in Example 1.

[0107] (4) The HLB value of the accelerator in this embodiment is 6.0, and other properties are the same as in Example 1.

[0108] (5) In the preparation process of the underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment, the ultrasonic dispersion power is 1.0 W / cm. 3 Ultrasonic treatment for 60 minutes; curing in seawater at 35℃ and a flow rate of 1.5 m / s for 24 hours.

[0109] Example 7

[0110] The underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment includes the following components: 70 parts of epoxy prepolymer containing dynamic disulfide bonds, 20 parts of environmentally responsive curing agent, 5 parts of self-healing microcapsules, and 1 part of accelerator.

[0111] The differences between this embodiment and Embodiment 1 are as follows:

[0112] (1) The preparation method of the epoxy prepolymer containing dynamic disulfide bonds in this embodiment is the same as that in Example 1, but the molar ratio of 4,4'-diaminodiphenyl disulfide to bisphenol A type epoxy resin is 1:3, and the chain extension degree is controlled at 15% to obtain an epoxy prepolymer containing dynamic disulfide bonds with an epoxy value of 0.55eq / 100g.

[0113] (2) In this embodiment, the environmentally responsive curing agent is made by mixing four-arm vinyl POSS with polyetheramine D400 at a vinyl:amine molar ratio of 1:5 and refluxing at 60°C for 24 hours; the quaternization is 50%, and other preparation conditions are the same as in Example 1.

[0114] (3) In the self-healing microcapsules of this embodiment, the SH content of thiol-terminated polysulfide rubber is 2.5 mmol / g, the average particle size is 80 μm, the wall thickness is 10 μm, and other preparation conditions are the same as in Example 1.

[0115] (4) The HLB value of the accelerator in this embodiment is 4.0, and other properties are the same as in Example 1.

[0116] (5) In the preparation process of the underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment, the ultrasonic dispersion power is 0.5 W / cm. 3 Ultrasonic treatment for 30 minutes; curing in seawater at 5℃ and a flow rate of 0.2 m / s for 48 hours.

[0117] Example 8

[0118] The underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment includes the following components: 60 parts of epoxy prepolymer containing dynamic disulfide bonds, 30 parts of environmentally responsive curing agent, 10 parts of self-healing microcapsules, and 2 parts of accelerator.

[0119] The differences between this embodiment and Embodiment 1 are as follows:

[0120] (1) The preparation method of the epoxy prepolymer containing dynamic disulfide bonds in this embodiment is the same as that in Example 1, but the molar ratio of 4,4'-diaminodiphenyl disulfide to bisphenol A type epoxy resin is 1:2.5, and the chain extension degree is controlled at 13%, so as to obtain an epoxy prepolymer containing dynamic disulfide bonds with an epoxy value of 0.28eq / 100g.

[0121] (2) In this embodiment, the environmentally responsive curing agent is made by mixing four-arm vinyl POSS with polyetheramine D400 at a vinyl:amine molar ratio of 1:6 and refluxing at 70°C for 36 hours; the degree of quaternization is 45%, the quaternizing agent is octadecane bromide, and the amount of tetrabutylammonium bromide is 1.2wt%; other preparation conditions are the same as in Example 1.

[0122] (3) In the self-healing microcapsules of this embodiment, the mass ratio of thiol-terminated polysulfide rubber to nano-montmorillonite is 1:1.8, the average particle size is 120 μm, and the wall thickness is 15 μm; other preparation conditions are the same as in Example 1.

[0123] (4) The accelerator in this embodiment is the esterification product of perfluoropolyether alcohol (average molecular weight 4000 Da) and maleic anhydride, with a degree of esterification of 96% and an HLB value of 5.5.

[0124] (5) In the preparation process of the underwater concrete self-healing material containing dynamic disulfide bonds in this embodiment, the stirring speed was 1100 rpm and the stirring time was 18 min; the ultrasonic dispersion frequency was 40 kHz and the power was 0.7 W / cm. 3 The ultrasonic treatment lasted for 45 minutes; the solution was then cured for 36 hours in a seawater environment at 25°C and a flow rate of 1.0 m / s. The repair layer thickness was 7 mm.

[0125] Compare with Example 1

[0126] The difference between this comparative example and Example 1 is that bisphenol A type epoxy resin is used instead of the epoxy prepolymer containing dynamic disulfide bonds in Example 1; all other aspects are consistent with Example 1.

[0127] Compare with Example 2

[0128] The difference between this comparative example and Example 1 is that a common polyetheramine curing agent (JEFFAMINE® T-403 manufactured by Huntsman) was used instead of the curing agent in Example 1, and no quaternization modification was performed; all other aspects are consistent with Example 1.

[0129] Compare with Example 3

[0130] The difference between this comparative example and Example 1 is that the accelerator is omitted; otherwise, they are consistent with Example 1.

[0131] Compare with Example 4

[0132] The difference between this comparative example and Example 1 is that in the preparation of the epoxy prepolymer containing dynamic disulfide bonds, the molar ratio of 4,4'-diaminodiphenyl disulfide to bisphenol A type epoxy resin is 1:4, and the chain extension degree is controlled at 20%; all other aspects are consistent with Example 1.

[0133] Compare with Example 5

[0134] The difference between this comparative example and Example 1 is that the degree of quaternization in the preparation of the environmentally responsive curing agent is 70% (exceeding the scope of the claims by 30%-50%); the rest are consistent with Example 1.

[0135] Compare with Example 6

[0136] The difference between this comparative example and Example 1 is that in the preparation of the self-healing microcapsules, the mass ratio of thiol-terminated polysulfide rubber to nano-montmorillonite is 1:4 (deviating from the optimal range); the average particle size is 200 μm (exceeding the range of 80-150 μm in the claims); all other aspects are consistent with Example 1.

[0137] Compare with Example 7

[0138] The difference between this comparative example and Example 1 is that the degree of esterification of the accelerator is 80% (lower than ≥90% in the claim) and the HLB value is 8.0 (the HLB value is too high); all other aspects are consistent with Example 1.

[0139] Compare with Example 8

[0140] The difference between this comparative example and Example 1 is that: in the preparation of the repair material, ultrasonic dispersion was not performed, and the microcapsules and promoter were mixed by mechanical stirring at 1000 rpm for 30 minutes; the rest is consistent with Example 1.

[0141] Compare with Example 9

[0142] The difference between this comparative example and Example 1 is that it was cured in a freshwater environment (not seawater) for 48 hours; all other aspects are the same as in Example 1.

[0143] Compare with Example 10

[0144] The difference between this comparative example and Example 1 is that the weight ratio of the hardener to the hydrophobic agent is 1:1.8; all other aspects are the same as in Example 1.

[0145] Compare with Example 11

[0146] The difference between this comparative example and Example 1 is that the thickness of the cured layer is 15 mm; all other aspects are the same as in Example 1.

[0147] Compare with Example 12

[0148] The difference between this comparative example and Example 1 is that the chain extension step was omitted in the preparation of the epoxy prepolymer, and the reaction product of 4,4'-diaminodiphenyl disulfide and bisphenol A type epoxy resin was directly purified; the rest is consistent with Example 1.

[0149] Compare with Example 13

[0150] The difference between this comparative example and Example 1 is that the self-healing microcapsules do not contain nano-montmorillonite and only use thiol-terminated polysulfide rubber as the core material; all other aspects are consistent with Example 1.

[0151] Compare with Example 14

[0152] The difference between this comparative example and Example 1 is that the esterification product of a common aliphatic alcohol and maleic anhydride (molecular weight 1000 Da, HLB value 3.0) is used instead of the esterification product of perfluoropolyether alcohol as the promoter; all other aspects are consistent with Example 1.

[0153] Example 15

[0154] The difference between this comparative example and Example 1 is that a common polyetheramine curing agent (T-403 polyetheramine, trifunctional polyetheramine, with an amine hydrogen equivalent of approximately 81) was directly mixed with ethylene oxide (1:1) to replace the curing agent in Example 1; all other aspects remained the same as in Example 1.

[0155] In this comparative example, the repair material was not fully cured, the resin matrix softened, and the crack healing rate could not be accurately measured.

[0156] Example 16

[0157] The difference between this comparative example and Example 1 is that the self-healing microcapsules are omitted; otherwise, they are consistent with Example 1.

[0158] Experimental Example

[0159] The repair materials prepared in the above examples or comparative examples were coated on the surface of reinforced concrete specimens with a thickness of 5 mm, and performance tests were conducted.

[0160] Curing degree: determined by DSC;

[0161] Bond strength: The initial bond strength and the bond strength after 200 wet and dry cycles were tested, and the strength retention rate was calculated.

[0162] Crack healing rate test method:

[0163] (1) A crack with a width of 150 μm was created on the surface of the sample (40 mm × 10 mm × 2 mm) by a three-point bending test. The initial state was recorded immediately after the crack was formed using a digital microscope (the initial crack was three-dimensionally scanned using a laser scanning confocal microscopy system specifically designed for underwater conditions, and the width, depth and length parameters of the initial crack were recorded); (2) The sample containing the crack was immersed in a 20°C seawater environment for 72 h to fully activate the self-healing mechanism; the entire repair process was carried out underwater to avoid environmental changes caused by air contact; (3) After the repair period, in Without removing the sample (keeping it underwater), the crack parameters at the same location were measured again using the same laser scanning confocal microscopy system; (4) Data processing: The point cloud data obtained by laser scanning was processed using professional three-dimensional data analysis software to reconstruct the three-dimensional model of the crack and accurately calculate the volume; (5) To ensure data accuracy, three representative areas of each sample were selected for scanning and measurement, and the average value was taken as the final result; (6) Calculation of crack healing rate: The crack healing rate was calculated using the crack volume change method, and the formula is as follows: Crack healing rate (%) = [(V1-V2) / V1] × 100%. Where: V1 is the initial crack volume (μm³); V2 is the residual crack volume after self-repair (μm³); (7) Result verification: The degree of crack closure was verified by underwater ultrasonic non-destructive testing to confirm the healing quality and integrity.

[0164] Chloride ion diffusion coefficient: determined by an electric acceleration method.

[0165] The test results are shown in Table 1 below:

[0166] Table 1

[0167]

[0168] Table 1 shows that: the underwater concrete self-healing material containing dynamic disulfide bonds in Example 2 has superior chloride ion barrier properties compared to Example 1; the underwater concrete self-healing material containing dynamic disulfide bonds in Example 3 exhibits excellent repair ability for narrower cracks; the underwater concrete self-healing material containing dynamic disulfide bonds in Example 4 has excellent repair ability for wider cracks (200 μm wide); and the underwater concrete self-healing material containing dynamic disulfide bonds in Example 5 still maintains good performance under lower temperature conditions. The underwater concrete self-healing materials containing dynamic disulfide bonds in Examples 1-8 all exhibit high curing degree (>92%), good bond durability (strength retention rate >85%), excellent crack healing rate (>90%), and extremely low chloride ion diffusion coefficient (≤2.5 × 10⁻⁶). -12 (m² / s). The performance of Comparative Examples 1-16 was significantly worse than that of Example 1.

[0169] In summary, the underwater concrete self-healing material containing dynamic disulfide bonds provided by this invention can achieve high curing degree (>92%) in seawater environments by using a specific curing agent; through the dual repair mechanism of epoxy prepolymer containing dynamic disulfide bonds and self-healing microcapsules, it achieves efficient self-repair (>90%) for cracks with a width ≤200μm; the underwater concrete self-healing material containing dynamic disulfide bonds of this invention has excellent bonding durability, with a bond strength retention rate of over 85% after 200 wet-dry cycles; the underwater concrete self-healing material containing dynamic disulfide bonds of this invention has excellent chloride ion barrier capability, with a chloride ion diffusion coefficient ≤2.5×10 -12 The self-healing efficiency is 1 / 40th that of traditional repair materials, achieved in m² / s. In contrast, the self-healing efficiency of the control example without dynamic disulfide bonds is significantly reduced; the control example without the curing agent of this invention exhibits insufficient curing degree and low bond strength retention in seawater; the control example without self-healing microcapsules has limited repair efficiency for larger cracks… In the underwater concrete self-healing material containing dynamic disulfide bonds of this invention, the components work synergistically to achieve rapid curing, high-strength bonding, and self-repairing functions in a seawater environment. This underwater concrete self-healing material containing dynamic disulfide bonds is particularly suitable for intelligent repair and long-term protection of concrete structures in harsh marine environments such as cross-sea bridge piers and deep-sea drilling platforms, and has significant engineering application value.

[0170] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-healing underwater concrete material containing dynamic disulfide bonds, characterized in that, It comprises the following components in parts by weight: Hardener, wherein the hardener is 50-70 parts of an epoxy prepolymer containing dynamic disulfide bonds; Hydrophobic agent, comprising 20-35 parts curing agent and 1-3 parts accelerator; The epoxy prepolymer containing dynamic disulfide bonds is prepared by a method comprising the following steps: A1. Mixing 4,4'-diaminodiphenyl disulfide with bisphenol A type epoxy resin and reacting under nitrogen protection to obtain a first intermediate product; A2. Adding 1,4-butanediol diglycidyl ether to extend the chain of the first intermediate product to obtain a second intermediate product; A3. The second intermediate product is precipitated and purified to obtain the epoxy prepolymer containing dynamic disulfide bonds; in step A1, the molar ratio of 4,4'-diaminodiphenyl disulfide to bisphenol A type epoxy resin is 1:(2-3); the reaction temperature is 80-100℃, and the reaction time is 4-6h; in step A2, the chain extension degree is controlled at 10%-15%; The curing agent is prepared by a method comprising the following steps: B1. Mixing four-arm vinyl POSS with polyetheramine D400 and refluxing in a solvent; B2. After the refluxing reaction is completed, adding a quaternizing agent to perform quaternization modification, thereby obtaining the curing agent; the degree of quaternization in step B2 is 30%-50%; The accelerator is an esterification product of perfluoropolyether alcohol and maleic anhydride, with an esterification degree ≥90%, a molecular weight of 2000-5000 Da, and an HLB value of 4-6. The hydrophobic agent also includes self-healing microcapsules, which are prepared by a method comprising the following steps: C1. Mixing and emulsifying thiol-terminated polysulfide rubber with nano-montmorillonite; C2. The self-healing microcapsules are obtained by coating with ethyl cellulose as the wall material using interfacial polymerization; in step C1, the mass ratio of the thiol-terminated polysulfide rubber to the nano-montmorillonite is 1:(1.5-2.5); the average particle size of the self-healing microcapsules is 80-150 μm, the wall thickness is 10-20 μm, and the core material content is ≥85%; The preparation method of the underwater concrete self-healing material containing dynamic disulfide bonds includes the following steps: (1) heating the epoxy prepolymer containing dynamic disulfide bonds to 40-50℃, adding a curing agent and stirring; (2) adding the accelerator, ultrasonically dispersing, and obtaining a mixture; (3) degassing the mixture and injecting it into a mold, and curing it in a seawater environment.

2. The underwater concrete self-healing material containing dynamic disulfide bonds as described in claim 1, characterized in that, In step A3, the epoxy value of the epoxy prepolymer containing dynamic disulfide bonds is 0.25-0.35 eq / 100g; In step A1, the epoxy value of the bisphenol A type epoxy resin is 0.45-0.55 eq / 100g.

3. The underwater concrete self-healing material containing dynamic disulfide bonds as described in claim 1, characterized in that, In step B1, the molar ratio of vinyl groups in the four-arm vinyl POSS to amine groups in polyetheramine D400 is 1:(5-8); the reflux reaction temperature is 60-80℃, and the reaction time is 24-48h; the solvent is toluene; in step B2, the quaternization modification temperature is 60-80℃, and the quaternization modification time is 6-12h.

4. The underwater concrete self-healing material containing dynamic disulfide bonds as described in claim 1, characterized in that, In step B2, the quaternizing agent includes hexadecane bromide and tetrabutylammonium bromide. The molar amount of hexadecane bromide is 30%-50% of the total molar amount of amino groups in polyetheramine D400, and the amount of tetrabutylammonium bromide is 0.5wt%-1.5wt% of the total mass of the addition product of tetra-arm vinyl POSS and polyetheramine D400 and hexadecane bromide.

5. The underwater concrete self-healing material containing dynamic disulfide bonds as described in claim 1, characterized in that, The dosage of the self-healing microcapsules is 5-15 parts.

6. The underwater concrete self-healing material containing dynamic disulfide bonds as described in claim 1, characterized in that, The weight ratio of the hardener to the hydrophobic agent is 1:(0.5-1.4).

7. The underwater concrete self-healing material containing dynamic disulfide bonds as described in claim 1, characterized in that, In step C2, the pH of the interfacial polymerization reaction is 4.5-5.5; In step C1, the emulsification is carried out using a homogenizer with a rotation speed of 10,000-15,000 rpm; the SH content of the thiol-terminated polysulfide rubber is 2.5-3.5 mmol / g, and the thickness of the nano-montmorillonite sheets is 1-3 nm.

8. The method for preparing underwater concrete self-healing material containing dynamic disulfide bonds as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Heat the epoxy prepolymer containing dynamic disulfide bonds to 40-50°C, add curing agent and stir; (2) Add the aforementioned accelerator, and disperse by ultrasonication to obtain a mixture; (3) After degassing, the mixture is injected into a mold and cured in a seawater environment; Step (2) also includes the step of adding the self-healing microcapsules.

9. The preparation method of the underwater concrete self-healing material containing dynamic disulfide bonds as described in claim 8, characterized in that, In step (1), after adding the curing agent, the stirring speed is 800-1200 rpm and the stirring time is 10-20 min; In step (2), the frequency of ultrasound is 40kHz, the ultrasound power is 0.5-1.0W / cm³, and the ultrasound time is 30-60 min. In step (3), the temperature of the seawater is 5-35℃, the flow rate is ≤1.5m / s, and the curing time is 24-48h.

10. The application of the underwater concrete self-healing material containing dynamic disulfide bonds as described in any one of claims 1-7 in the repair of concrete matrix in seawater; the thickness of the repair layer formed by the underwater concrete self-healing material containing dynamic disulfide bonds is 3-10 mm.

11. The application as described in claim 10, characterized in that, When the underwater concrete self-healing material containing dynamic disulfide bonds is applied to the repair of concrete substrates in seawater, the amount of the underwater concrete self-healing material containing dynamic disulfide bonds per square meter of concrete surface shall be ≥500g.

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