Pickering emulsion as well as preparation method and application thereof

Abstract

The invention relates to the technical field of building material repair, in particular to Pickering emulsion and a preparation method and application thereof. The Pickering emulsion is an oil-in-water emulsion, a water phase of the Pickering emulsion comprises water, colloidal particles and water-soluble cellulose ether, and the colloidal particles and the water-soluble cellulose ether are dispersed in the water; the oil phase comprises fatty acid ester; at least part of the colloidal particles and the water-soluble cellulose ether are distributed on the surfaces of liquid drops of the oil phase, the colloidal particles and the water-soluble cellulose ether synergistically play a role of an emulsifier, hydrogen bonds are formed between the colloidal particles and the water-soluble cellulose ether, and / or both the colloidal particles and the water-soluble cellulose ether are negatively charged, so that the colloidal particles are uniformly dispersed in the water phase; the liquid drops of the oil phase are uniformly and stably dispersed in the water phase without contact coalescence. Therefore, the Pickering emulsion disclosed by the invention still has good storage stability and coalescence stability without a surfactant or an organic modifier, and also has biocompatibility and environmental friendliness.

Description

Technical Field

[0001] The present application relates to the technical field of building material repair, and in particular to Pickering emulsion and its preparation method and application. Background Art

[0002] Concrete is prone to cracks of varying degrees due to a variety of factors such as material properties, construction technology, load effects and external environment, which can weaken the overall strength and stability. It may also cause harmful substances such as chloride ions and sulfate ions to penetrate into the concrete, accelerating the deterioration of the concrete and the corrosion of steel bars. Therefore, it is particularly important to repair concrete cracks and improve its durability.

[0003] To this end, people have proposed self-repairing concrete for pipes. By imitating the distribution of vascular networks and the form of material transmission in organisms, pipes are embedded in the concrete. When the concrete cracks, the cracks extend to the internal pipes. Under the action of capillary force, gravity, surface tension and negative pressure, the repair agent is released into the cracks for repair. Moreover, the repair material can be pumped from the outside through the pipes to achieve multiple self-repairs. For example, brittle materials such as glass can be embedded before concrete pouring. For example, 3D printing technology can be used to construct a pipe template in situ after cement pouring and curing. After cement hydration is completed, a hydrophobic pipe is formed.

[0004] Among them, the latter method often requires Pickering emulsion as 3D printing ink. Pickering emulsion is an emulsion stabilized by solid particles adsorbed on the contact surface of the water phase and the oil phase. The solid particles can prevent the droplets from agglomerating and keep the emulsion stable. However, due to the surface wettability of the solid particles, these Pickering emulsions often need to undergo complex chemical modifications or use surfactants to remain stable, which is expensive and time-consuming, and may also cause harm to human health and the environment. Moreover, the rheological properties (shear thinning properties, storage modulus and loss modulus, yield stress, etc.), self-supporting strength, emulsion stability and other properties of these existing Pickering emulsions are still not ideal and cannot meet the needs of pipeline self-repairing concrete. Summary of the invention

[0005] The purpose of the present application is to provide a Pickering emulsion and a preparation method thereof, aiming to solve the technical problem in the prior art that the Pickering emulsion used for self-repairing concrete needs to be chemically modified or use a surfactant to maintain stability.

[0006] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0007] In a first aspect, the present application provides a Pickering emulsion, which is an oil-in-water emulsion, wherein the aqueous phase comprises water and colloidal particles, and a water-soluble cellulose ether, and the colloidal particles and the water-soluble cellulose ether are dispersed in water; and the oil phase comprises a fatty acid ester;

[0008] At least part of the colloidal particles and the water-soluble cellulose ether are distributed on the surface of the droplets of the oil phase, wherein hydrogen bonds are formed between the colloidal particles and the water-soluble cellulose ether and / or both carry negative charges.

[0009] The present application is an oil-in-water emulsion containing colloidal particles in the aqueous phase, wherein the aqueous phase is a continuous phase and the aqueous phase is a dispersed phase, constituting a Pickering emulsion. Moreover, the colloidal particles in the aqueous phase form hydrogen bonds with the water-soluble cellulose ether and / or both carry a negative charge, so that the colloidal particles are uniformly dispersed in the aqueous phase. At the same time, at least part of the colloidal particles and the water-soluble cellulose ether are distributed on the surface of the droplets of the oil phase, and the two synergistically act as emulsifiers, so that the droplets of the oil phase are uniformly and stably dispersed in the aqueous phase without contact and aggregation. Therefore, the Pickering emulsion of the present application does not require a surfactant or an organic modifier, and still has good storage stability and aggregation stability, and is also biocompatible and environmentally friendly.

[0010] In a second aspect, the present application provides a method for preparing the Pickering emulsion of the above-mentioned application, comprising the following steps:

[0011] The raw materials including the oil phase are added to the solution of the water phase for emulsification.

[0012] The preparation method of the present application emulsifies the above-mentioned raw materials of the oil phase and the solution of the water phase. The colloidal particles and water-soluble cellulose ethers in the water phase synergistically act as emulsifiers, and the oil phase will form droplets. At least part of the colloidal particles and water-soluble cellulose ethers are distributed on the surface of the oil phase droplets, so that the oil phase droplets are evenly and stably dispersed in the water phase without contact and aggregation, thereby obtaining the above-mentioned Pickering emulsion without the need for surfactants or organic modifiers, and can be used for pipeline self-repairing concrete. The preparation method is process-controllable, and the obtained Pickering emulsion has good storage stability and aggregation stability, and is also biocompatible and environmentally friendly.

[0013] In a third aspect, the present application provides a self-repairing concrete pipe component, including a component base and a drain pipe. The drain pipe is arranged inside the component base and connected to the outside. The drain pipe is formed by curing the Pickering emulsion as described in the above text application.

[0014] The self-repairing concrete pipe component of the present application includes a component base and an internal hydrophobic pipe. When cracks appear in the component base, a crack repair agent can be transported into the hydrophobic pipe, so that the crack repair agent flows along the hydrophobic pipe into the interior of the component base, penetrates into the cracks and fills them. The crack repair agent can repair the cracks in the component base in time. Since the hydrophobic pipe is formed by the solidification of the above-mentioned Pickering emulsion, the formed pipe is hydrophobic, and the crack repair agent will not seep out and be lost during transportation, and can reach the cracks directly. The self-repairing concrete pipe component of the present application is also biocompatible and environmentally friendly.

[0015] In a fourth aspect, the present application provides a method for preparing a pipeline self-repairing concrete component, comprising the following steps:

[0016] Constructing a pipeline template in concrete slurry, wherein the pipeline template is prepared by molding the Pickering emulsion in the above-mentioned application or the Pickering emulsion prepared by the preparation method in the above-mentioned application;

[0017] The concrete slurry containing the pipeline template is subjected to a hydration reaction to obtain a pipeline self-repairing concrete component.

[0018] The preparation method of the present application first prepares concrete slurry. Concrete slurry is a typical porous material with many interconnected micropores inside. Before the concrete slurry solidifies, the Pickering emulsion can be molded in the concrete slurry. Since the above Pickering emulsion has a certain self-supporting strength, it can be filled and combined in the concrete slurry to construct a pipeline template. Then a hydration reaction is carried out, and the water phase of the Pickering emulsion will be consumed until the oil-in-water emulsion structure is destroyed, and the fatty acid ester of the oil phase will penetrate into the surrounding concrete. When the temperature is lowered, the fatty acid ester solidifies and forms a hydrophobic pipeline in the concrete component matrix, thereby obtaining a pipeline self-repairing concrete component. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is the preparation process of the Pickering emulsion of Example 1;

[0021] Figure 2 It is the infrared spectrum test result figure of the water phase component of the Pickering emulsion of Example 3 and Example 9;

[0022] Figure 3 3. It is a graph showing the test results of the Zeta potential of the water phase in the Pickering emulsions of Examples 3, 6 to 11;

[0023] Figure 4 is a schematic diagram of the relationship between the viscosity and shear rate of the Pickering emulsions of Examples 1 to 5;

[0024] Figure 5 Schematic diagram of storage modulus and loss modulus of Pickering emulsions of Examples 1 to 5 under shear stress scanning;

[0025] Figure 6 is a schematic diagram of the relationship between the viscosity and shear rate of the Pickering emulsions of Examples 9, 10, 3, and 11;

[0026] Figure 7 is a schematic diagram of the storage modulus and loss modulus of the Pickering emulsions of Examples 9, 10, 3, and 11 under shear stress scanning;

[0027] Figure 8 is a schematic diagram of the relationship between the viscosity and shear rate of the Pickering emulsions of Examples 12, 3, 13, and 14;

[0028] Fig. 9 is a schematic diagram of the storage modulus and loss modulus of the Pickering emulsions of Examples 12, 3, 13, and 14 under shear stress scanning;

[0029] Fig.10 The preparation process of using Pickering emulsion in preparing pipeline self-repairing concrete parts according to Example 3;

[0030] Fig.11 is a schematic diagram of forming pipes of different diameters in concrete by 3D printing using Pickering emulsion in Example 3;

[0031] Fig.12 It is a comparison diagram before and after the crack repair of the pipeline self-repairing concrete component embodiment. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0033] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0034] In this application, "at least one" means one or more, "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0035] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0036] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass in the embodiment description of the present application can be μg, mg, g, kg and other mass units known in the chemical industry.

[0037] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0038] Explanation of terms in this application:

[0039] Storage stability: whether oil-water stratification occurs when the emulsion is stored for a long time.

[0040] Coalescence stability: for example, in an oil-in-water emulsion, whether the droplets of the oil phase will contact and combine to form large droplets.

[0041] Oil-water ratio: The oil-water ratio in this application refers to the volume ratio of the oil phase to the water phase.

[0042] The first aspect of the embodiment of the present application provides a Pickering emulsion, which is an oil-in-water emulsion, wherein the aqueous phase includes water and colloidal particles, and water-soluble cellulose ether, and the colloidal particles and water-soluble cellulose ether are dispersed in water; and the oil phase includes fatty acid esters;

[0043] At least part of the colloidal particles and the water-soluble cellulose ether are distributed on the surface of the droplets of the oil phase, wherein hydrogen bonds are formed between the colloidal particles and the water-soluble cellulose ether and / or both carry negative charges.

[0044] The embodiment of the present application is an oil-in-water emulsion containing colloidal particles in the aqueous phase, wherein the aqueous phase is a continuous phase and the aqueous phase is a dispersed phase, constituting a Pickering emulsion. Moreover, the colloidal particles in the aqueous phase form hydrogen bonds with the water-soluble cellulose ether and / or both carry a negative charge, so that the colloidal particles are uniformly dispersed in the aqueous phase. At the same time, at least part of the colloidal particles and the water-soluble cellulose ether are distributed on the surface of the droplets of the oil phase, and the two synergistically act as emulsifiers, so that the droplets of the oil phase are uniformly and stably dispersed in the aqueous phase without contact and aggregation. Therefore, the Pickering emulsion of the embodiment of the present application does not require a surfactant or an organic modifier, and still has good storage stability and aggregation stability, and is also biocompatible and environmentally friendly.

[0045] Pickering emulsion also has good shear thinning, thixotropy, and anti-deformation properties, and has a certain self-supporting strength, so the subsequent molding performance is good. When applied to pipeline self-repairing concrete, after the water phase of Pickering emulsion is consumed, the fatty acid ester of the oil phase will seep out and solidify, forming a hydrophobic pipeline connected to the outside world.

[0046] About the water phase:

[0047] The water phase covers the oil phase, and the water phase contains water, colloidal particles, and water-soluble cellulose ether. In some embodiments, the colloidal particles include at least one of montmorillonite, kaolin, nano-silica, laponite, and sepiolite, and sodium-based montmorillonite can be selected. These colloidal particles are dispersed in the water phase and at least partially distributed on the surface of the droplets of the oil phase, acting as an emulsifier, thereby stabilizing the droplets of the oil phase, so that the water phase and the oil phase form a Pickering emulsion. At the same time, the colloidal particles can form hydrogen bonds with the water-soluble cellulose ether, synergistically stabilize the droplets of the oil phase, and improve the storage stability and aggregation stability of the emulsion. The colloidal particles can also carry a negative charge with the water-soluble cellulose ether, reduce the Zeta potential of the water phase, improve the stability and dispersibility of the colloidal particles in the water phase, and achieve the storage stability and aggregation stability of the emulsion without a surfactant or an organic modifier, and also have biocompatibility and environmental friendliness.

[0048] In some embodiments, the Dv50 particle size of the colloidal particles can be 1 to 1000 nm. In the exemplary embodiments, it can include but is not limited to any value of 1 nm, 10 nm, 50 nm, 100 nm, 1000 nm or a range between any two values. Colloidal particles of these particle sizes are conducive to uniform dispersion in the aqueous phase, while improving the desorption energy of the colloidal particles at the oil-water interface, improving the stability of the oil phase droplets, and further improving the storage stability and aggregation stability of the emulsion.

[0049] In some embodiments, the contact angle of the colloidal particles is 20° to 25°. The contact angle of the colloidal particles reflects their wetting properties at the oil-water interface, thereby affecting the stability of the water-in-oil emulsion. In the exemplary embodiment, it may include but is not limited to any value of 20°, 22°, 24°, 25° or a range between any two values. The colloidal particles with these contact angles are advantageously wetted by the water phase first, thereby forming a stable water-in-oil emulsion, and improving the storage stability and aggregation stability of the Pickering emulsion.

[0050] In some embodiments, the concentration of the colloidal particles in the water phase is 1 wt% to 5 wt%. In the exemplary embodiment, it may include but is not limited to any value of 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt% or a range between any two values, and 3 wt% may be selected. The concentration of the colloidal particles will affect the number of colloidal particles distributed on the surface of the oil phase droplets. These concentrations enable these colloidal particles to form a monolayer-like morphology on the surface of the oil phase droplets, thereby giving full play to the role of the emulsifier, forming a stable water-in-oil emulsion, and improving the storage stability and aggregation stability of the Pickering emulsion. In addition, the colloidal particles at these concentrations also give the Pickering emulsion shear thinning, thixotropy, and deformation resistance, which is beneficial to subsequent molding.

[0051] In some embodiments, the water-soluble cellulose ether may include anionic, cationic and nonionic types, and may include at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose and ethyl cellulose. These water-soluble cellulose ethers may form hydrogen bonds with the above-mentioned colloidal particles and / or contain negative charges, and synergistically act as emulsifiers, synergistically enhance the uniform and stable dispersion of oil phase droplets in the aqueous phase, so that the storage stability and aggregation stability of the Pickering emulsion can be improved without the need for surfactants and organic modifiers, and the emulsion is also biocompatible and environmentally friendly.

[0052] In some embodiments, the concentration of the water-soluble cellulose ether in the aqueous phase is 0.1wt% to 4wt%. In the exemplary embodiment, it may include but is not limited to any value of 0.1wt%, 0.25wt%, 0.5wt%, 1wt%, 3wt%, 4wt% or any range between two values, and 3wt% may be selected. The water-soluble cellulose ethers in these proportions can form hydrogen bonds with the above-mentioned colloidal particles and / or have negative charges, thereby synergistically acting as emulsifiers to improve the storage stability and aggregation stability of the Pickering emulsion. In addition, the water-soluble cellulose ethers in these concentrations also cooperate with the colloidal particles to give the Pickering emulsion shear thinning, thixotropy, and deformation resistance, which is beneficial to subsequent molding.

[0053] In some embodiments, the pH value of the aqueous phase is 6 to 8. Changes in pH value can affect the hydrophobicity of the colloidal particles and can adjust the adsorption of the colloidal particles on the surface of the oil phase droplets. The aqueous phase with these pH values ​​can improve the storage stability and aggregation stability of the Pickering emulsion.

[0054] In some embodiments, the Zeta potential of the water phase is ≤ -20 mV, that is, the Zeta potential is negative, and the absolute value is not less than 20. In the exemplary embodiment, it may include but is not limited to any value of -20 mV, -30 mV, -35 mV or a range between any two values. The water phases with these Zeta potentials are beneficial to improving the stability and dispersibility of the colloidal particles in the water phase, and improving the storage stability and aggregation stability of the emulsion.

[0055] About the oil phase:

[0056] The oil phase containing fatty acid esters makes the oil-water interface have appropriate tension and is conducive to the interaction with the colloidal particles, so that at least part of the colloidal particles are distributed on the surface of the oil phase droplets. In some embodiments, the solid-liquid phase transition temperature of the fatty acid ester is 25 to 50°C. In the exemplary embodiment, it may include but is not limited to any value of 25°C, 30°C, 35°C, 45°C, 50°C or a range between any two values. When applied to self-repairing concrete, after the water phase of the Pickering emulsion is consumed, the fatty acid esters in the oil phase will solidify to form a hydrophobic pipeline connected to the outside world. Therefore, these fatty acid esters need to remain liquid in the emulsion and remain solid in the use scenario of the pipeline self-repairing concrete. When the emulsion is prepared and stored, ensure that the temperature is higher than the solid-liquid phase transition temperature, and the temperature in the use scenario needs to be lower than the solid-liquid phase transition temperature.

[0057] As shown in the example, the solid-liquid phase transition temperature of fatty acid ester is 28°C. When preparing and storing the emulsion, the temperature is kept above 28°C to keep it in liquid state. When applying, the final use scene temperature is less than 28°C to keep it in solid hydrophobic pipe. Therefore, the above solid-liquid phase transition temperature is suitable for common use scenes. When it is necessary to apply it to extremely hot scenes, it is necessary to select fatty acid esters with higher solid-liquid phase transition temperatures to ensure that the fatty acid esters are solid at the temperature in the use scene, and the temperature when preparing the emulsion and storing it is also adjusted accordingly.

[0058] In some embodiments, the fatty acid ester includes at least one of methyl palmitate, methyl heptadecanoate, methyl octadecanoate, methyl eicosanoate, ethyl hexadecanoate, ethyl heptadecanoate, and ethyl octadecanoate. These fatty acid esters can be used in the oil phase of Pickering emulsions and can form hydrophobic pipes after curing. Among them, the solid-liquid phase transition temperature of methyl palmitate is 28°C, and the self-repairing concrete is suitable for use scenarios with a temperature less than 28°C; the solid-liquid phase transition temperature of methyl heptadecanoate is 30°C; the solid-liquid phase transition temperature of methyl octadecanoate is between 37°C and 41°C; the solid-liquid phase transition temperature of methyl eicosanoate is between 45°C and 48°C; the solid-liquid phase transition temperature of ethyl hexadecanoate is between 24°C and 26°C; the solid-liquid phase transition temperature of ethyl heptadecanoate is 28°C; the solid-liquid phase transition temperature of ethyl octadecanoate is between 34°C and 38°C. In addition to these fatty acid esters, other homologues can also be used, and according to their corresponding solid-liquid phase transition temperatures, they can be applied to different use scenarios of pipeline self-repairing concrete.

[0059] In some embodiments, the Dv50 particle size of the oil phase droplets is 10 to 30 μm. In the exemplary examples, it may include but is not limited to any value of 10 μm, 15 μm, 20 μm, 25 μm, 30 μm or a range between any two values. The oil phase droplets of these particle sizes are conducive to uniform dispersion of the droplets in the water phase, reduce the occurrence of agglomeration, and can also cooperate with the water phase to give the Pickering emulsion shear thinning, thixotropy, and deformation resistance, which is beneficial to subsequent molding.

[0060] About Lotion:

[0061] The Pickering emulsion formed by the above-mentioned water phase and oil phase has good stability without adding surfactants or organic modifiers. In some embodiments, the oil-water ratio of the Pickering emulsion is 1: (2-5). In the exemplary embodiment, it may include but is not limited to any ratio of 1:2, 1:3, 1:4, 1:5 or a range between any two ratios, and 1:3 may be selected. These oil-water ratios are beneficial to improving the storage stability and aggregation stability of the Pickering emulsion. At the same time, these oil-water ratios are also beneficial to improving shear thinning, thixotropy, and deformation resistance, have a certain self-supporting strength, and improve the molding performance of the Pickering emulsion.

[0062] The second aspect of the present application embodiment provides a method for preparing the Pickering emulsion of the above application embodiment, comprising the following steps:

[0063] S10. Adding the raw materials including the oil phase into the solution of the water phase for emulsification treatment.

[0064] The preparation method of the embodiment of the present application emulsifies the above-mentioned raw materials of the oil phase and the solution of the water phase, and the colloidal particles and water-soluble cellulose ether in the water phase synergistically act as emulsifiers, and the oil phase will form droplets, and at least part of the colloidal particles and water-soluble cellulose ether are distributed on the surface of the oil phase droplets, so that the oil phase droplets are uniformly and stably dispersed in the water phase without contact and aggregation, so that the above-mentioned Pickering emulsion can be prepared without surfactants and organic modifiers, and can be used for pipeline self-repairing concrete. The preparation method is process-controllable, and the prepared Pickering emulsion has good storage stability and aggregation stability, and is also biocompatible and environmentally friendly.

[0065] Among them, the aqueous phase solution can be prepared first, and colloidal particles can be added to water first, and then water-soluble cellulose ether is added after uniform dispersion to obtain an aqueous phase solution. The types and amounts of colloidal particles and water-soluble cellulose ether can refer to the relevant records in the above Pickering emulsion. Then, the heated liquid fatty acid ester is added to the aqueous phase solution as the raw material of the oil phase, and the proportion can be made according to the above oil-water ratio, and finally an emulsification treatment is performed.

[0066] Emulsification treatment can be carried out by high-pressure homogenization, ultrasound, microfluidics, membrane emulsification, electric field emulsification and the like. Optionally, homogenization and emulsification can be carried out by a high-pressure homogenizer. The speed of the high-pressure homogenizer can be 10,000 to 20,000 rpm, and the homogenization time can be 5 to 20 minutes. The colostrum is prepared into a Pickering emulsion through the cavitation, turbulence and shearing effects of the machine.

[0067] A third aspect of an embodiment of the present application provides a self-repairing concrete pipe component, including a component base and a drain pipe. The drain pipe is arranged inside the component base and connected to the outside. The drain pipe is formed by curing the Pickering emulsion in the above text application embodiment.

[0068] The self-repairing concrete pipe component of the embodiment of the present application includes a component base and an internal hydrophobic pipe. When cracks appear in the component base, a crack repair agent, such as a polyurethane crack repair agent, can be transported into the hydrophobic pipe, so that the crack repair agent flows into the interior of the component base along the hydrophobic pipe, penetrates into the cracks and fills them. The crack repair agent can repair the cracks in the component base in time. Since the hydrophobic pipe is formed by curing the above-mentioned Pickering emulsion, the formed pipe is hydrophobic, and the crack repair agent will not seep out and be lost during transportation, and can reach the cracks directly. The self-repairing concrete pipe component of the embodiment of the present application is also biocompatible and environmentally friendly.

[0069] In some embodiments, the hydrophobic channel can be a common three-dimensional regular shape, such as a matrix, honeycomb, grid, spiral, etc., or an irregularly shaped channel, and can also contain many capillary channels in addition to the main channel. In some embodiments, the diameter of the hydrophobic channel is 0.6 to 3.5 mm, and in the exemplary examples, it can include but is not limited to any value of 0.6 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, or a range between any two values. The hydrophobic channels of these diameters are conducive to the delivery of the repair agent.

[0070] A fourth aspect of the present application provides a method for preparing a pipeline self-repairing concrete component, comprising the following steps:

[0071] S01. Constructing a pipeline template in a concrete slurry, the pipeline template is prepared by the Pickering emulsion prepared by the above text application example or the Pickering emulsion prepared by the above text application example preparation method by molding;

[0072] S02. The concrete slurry containing the pipeline formwork is subjected to a hydration reaction to obtain a pipeline self-repairing concrete component.

[0073] The preparation method of the embodiment of the present application first prepares concrete slurry. Concrete slurry is a typical porous material with many interconnected micropores inside. Before the concrete slurry solidifies, the Pickering emulsion can be molded in the concrete slurry. Since the above Pickering emulsion has a certain self-supporting strength, it can be filled and combined in the concrete slurry to construct a pipeline template. Then a hydration reaction is carried out, and the water phase of the Pickering emulsion will be consumed until the oil-in-water emulsion structure is destroyed, and the fatty acid ester of the oil phase will penetrate into the surrounding concrete. When the temperature is lowered, the fatty acid ester solidifies and forms a hydrophobic pipeline in the concrete component matrix, thereby obtaining a pipeline self-repairing concrete component.

[0074] [Step S01]

[0075] The concrete slurry in step S01 may be a cement-based slurry, the cement may be ordinary Portland cement, the strength may be PO 42.5 level, the concrete slurry may also contain aggregate, auxiliary cementitious materials, water reducing agent and other ingredients, and the concrete slurry may be prepared according to a water-cement ratio of 0.3 to 0.5.

[0076] In some embodiments, the emulsion molding process includes a 3D printing process, using the Pickering emulsion as printing ink, and the 3D printing process is conducive to the molding of the pipe template, and at the same time, it is conducive to the formation of the pipe template into a preset shape and size, and the pipe in the final self-repairing concrete part can be a preset shape and size, thereby improving the self-repairing effect. Since the Pickering emulsion mentioned above has a certain self-supporting strength, it can be filled and combined in the concrete slurry to construct the pipe template.

[0077] During 3D printing, the printing needle can be inserted into the concrete slurry to extrude the Pickering emulsion while adjusting the air pressure, needle movement speed and needle inner diameter according to a predetermined program to control the direction, shape, size and other parameters of the pipe template. After printing is completed, a pipe template that is connected inside and outside is formed.

[0078] In addition, the emulsion may be first molded to construct a pipe template, and then the concrete slurry may be poured on the pipe, so that the pipe template is set in the concrete slurry and communicated with the outside.

[0079] [Step S02]

[0080] Step S02 performs a hydration reaction, during which the water phase of the Pickering emulsion is continuously consumed, destroying the structure of the water-in-oil emulsion, causing the fatty acid ester of the oil phase to flow out and penetrate into the surrounding concrete. In the early stage of the hydration reaction, the fatty acid ester remains in a liquid state due to the heat release of the hydration reaction. In the later stage of the hydration reaction, the temperature decreases, and the fatty acid ester solidifies to form a hydrophobic pipe, thereby obtaining a pipe self-repairing concrete component.

[0081] The following describes the invention in conjunction with specific embodiments.

[0082] Example 1

[0083] This embodiment provides a Pickering emulsion and a preparation method thereof. The Pickering emulsion is an oil-in-water emulsion, wherein the aqueous phase contains water, 1 wt% sodium-based montmorillonite (colloidal particles), and 3 wt% carboxymethyl cellulose (water-soluble cellulose ether), and at least part of the montmorillonite and carboxymethyl cellulose are distributed on the surface of the droplets of the oil phase. The oil phase is methyl palmitate, and the oil-water volume ratio is 1:3.

[0084] The preparation method comprises the following steps:

[0085] like Figure 1 As shown, montmorillonite was added to 4.5 mL of deionized water, magnetically stirred for 10 min until the montmorillonite was evenly dispersed in the water, and carboxymethyl cellulose was added to make the mixed solution contain 1 wt% montmorillonite and 3 wt% carboxymethyl cellulose. Then 1.5 mL of methyl palmitate dissolved by heating was added, and the oil-water volume ratio was 1:3, and then added to a homogenizer and homogenized at 13400 rpm for 10 min to obtain a Pickering emulsion.

[0086] Example 2

[0087] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 1 only in that the concentration of montmorillonite in the water phase is changed to 2 wt %, and the other aspects are the same.

[0088] Example 3

[0089] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 1 only in that the concentration of montmorillonite in the water phase is changed to 3 wt %, and the other aspects are the same.

[0090] Example 4

[0091] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 1 only in that the concentration of montmorillonite in the water phase is changed to 4 wt %, and the other aspects are the same.

[0092] Example 5

[0093] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 1 only in that the concentration of montmorillonite in the water phase is changed to 5 wt %, and the other aspects are the same.

[0094] Example 6

[0095] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 3 only in that the concentration of carboxymethyl cellulose in the aqueous phase is changed to 0.1 wt %, and the rest are the same.

[0096] Example 7

[0097] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 3 only in that the concentration of carboxymethyl cellulose in the aqueous phase is changed to 0.25 wt %, and the rest are the same.

[0098] Example 8

[0099] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 3 only in that the concentration of carboxymethyl cellulose in the aqueous phase is changed to 0.5 wt %, and the rest are the same.

[0100] Example 9

[0101] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 3 only in that the concentration of carboxymethyl cellulose in the aqueous phase is changed to 1 wt %, and the other contents are the same.

[0102] Example 10

[0103] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 3 only in that the concentration of carboxymethyl cellulose in the aqueous phase is changed to 2 wt %, and the other contents are the same.

[0104] Embodiment 11

[0105] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 3 only in that the concentration of carboxymethyl cellulose in the aqueous phase is changed to 4 wt %, and the other contents are the same.

[0106] Example 12

[0107] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 3 only in that the oil-water volume ratio is changed to 1:2, and the rest is the same.

[0108] Example 13

[0109] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 3 only in that the oil-water volume ratio is changed to 1:4, and the rest is the same.

[0110] Embodiment 14

[0111] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Embodiment 3 only in that the oil-water volume ratio is changed to 1:5, and the rest is the same.

[0112] Comparative Example 1

[0113] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Example 3 only in that a sodium alginate solution with a concentration of 3 wt % is used as the aqueous phase, and Tween 80 is used as an oil-water interface stabilizer, and the rest are the same.

[0114] Comparative Example 2

[0115] This embodiment provides a Pickering emulsion and a preparation method thereof, which is different from Example 3 only in that a hectorite solution with a concentration of 3 wt % is used as the water phase, and didodecyl dimethyl ammonium bromide is used as an oil-water interface stabilizer, and the rest are the same.

[0116] The differences between the embodiments and the comparative examples are shown in Table 1 below:

[0117] Table 1

[0118]

[0119]

[0120] Related performance tests and result analysis

[0121] 1. Infrared spectrum test

[0122] The montmorillonite colloid aqueous solution, carboxymethyl cellulose aqueous solution, and the aqueous phases in Example 3 and Example 9 were subjected to infrared spectroscopy testing. The results are as follows: Figure 2 As shown, Figure 2 The MMT in it stands for montmorillonite, and the CMC stands for carboxymethyl cellulose.

[0123] It can be seen that montmorillonite has a -1 There is an absorption peak at 3448 cm-1 caused by the stretching vibration of -OH of surface water molecules. -1 Nearby, an absorption peak caused by the stretching of water molecules between the layers appears, and the bending vibration of water molecules between the layers appears at 1641cm -1 This indicates that the MMT sheet contains crystal water. -1 and 525cm -1 An absorption peak caused by Si-O stretching and bending vibration appears nearby.

[0124] CMC at 2920cm -1 The absorption peak nearby is the CH2 asymmetric stretching vibration mode, 1603cm -1 The absorption peak at 1422cm is the C=O stretching vibration mode. -1 The absorption peak at 1333 cm is the CH2 bending vibration mode. -1 The absorption peak at is the CH2 out-of-plane rocking vibration mode.

[0125] When the aqueous phase contains 3wt% MMT and 1wt% CMC, the -1 The Si-O stretching peak intensity at 525cm -1 The peak at 1030cm disappeared, and the characteristic peak of CMC for CH2 almost disappeared. As the amount of CMC increased to 3wt%, the peak at 1030cm-1 The Si-O stretching peak at the position almost disappears. These results indicate that there is a strong hydrogen bonding between the CH2 group on the CMC chain and the Si-O bond on the MMT. In other words, the CMC molecules are adsorbed on the edge of the MMT board in this way. CMC, as a polymer reagent with many side chains, can be bound to the surface of the montmorillonite colloidal particles. This result shows that in the Pickering emulsion system, CMC can assist the MMT particles in stabilizing the emulsion. Under the synergistic effect of the two, the droplets of the oil phase will not easily agglomerate, and no surfactant or organic modifier is required in Comparative Examples 1 and 2, which is biocompatible and environmentally friendly.

[0126] 2. Zeta potential analysis

[0127] The water phase in the Pickering emulsions of Examples 3, 6 to 11 was tested for Zeta potential. The results are as follows: Figure 3 As shown, Figure 3 The MMT in the formula stands for montmorillonite, and the CMC stands for carboxymethyl cellulose. The surface of the montmorillonite layer is negatively charged, and carboxymethyl cellulose also exhibits negative charges in aqueous solution because of the large number of carboxyl groups in its chemical structure. The Zeta potential of MMT alone is -3.4mV, and the Zeta potential of CMC alone is -25.6mV.

[0128] Figure 3 It can be seen that the Zeta potential changes of 3wt% MMT and different contents of CMC in the mixed solution. Compared with the pure MMT solution, the Zeta potential of the mixed solution of MMT and CMC decreased significantly, and with the continuous addition of CMC, the Zeta potential decreased significantly, that is, the Zeta potential is negative, and the absolute value is getting larger and larger, which means that the dispersion and stability are better. When the concentration of CMC increases to 4wt%, the Zeta potential of the solution reaches -36.2mV, indicating that it has good colloidal stability and dispersibility. This test analysis proves that these two negatively charged substances in the aqueous phase can further improve the stability of the Pickering emulsion.

[0129] 3. Stability test

[0130] The Pickering emulsion stabilized by montmorillonite / carboxymethyl cellulose has good storage stability. The Pickering emulsions of Examples 6 to 9, in which the aqueous phase contains 3 wt% montmorillonite and 0.1 wt%, 0.25 wt%, 0.5 wt% and 1 wt% carboxymethyl cellulose, respectively, the prepared Pickering emulsions with an oil-water ratio of 1:3 can be stored for more than 2 months without stratification.

[0131] The Pickering emulsions of Examples 3 and 9 to 14 were centrifuged at 5000 rpm for 5 min. The Pickering emulsions prepared by containing 3 wt % of montmorillonite and more than 1 wt % of carboxymethyl cellulose in the aqueous phase did not delaminate.

[0132] 4. Thixotropy test

[0133] The shear viscosity and modulus of the emulsion samples of Examples 1 to 14 and Comparative Examples 1 and 2 were measured using a rheometer (Inton Pr MCR 302) at a temperature of 50°C. All samples were tested at 10 s -1 Perform pre-shearing. The shear rate is increased from 0.01s to -1 Increase to 100s -1 To monitor the apparent shear viscosity, the linear viscoelastic range was determined at a shear stress (0.01 to 1000) at a fixed frequency of 10 rad / s, and the storage modulus (G') and loss modulus (G") were recorded.

[0134] The montmorillonite contents in Examples 1 to 5 are 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%, respectively, increasing gradually, and the others are the same. Figure 4 The relationship between the viscosity and shear rate of the emulsions of these examples is shown. Figure 5 The storage modulus and loss modulus of these example emulsions under shear stress sweep are shown. Figure 4 , Figure 5 The MMT in the formula stands for montmorillonite.

[0135] The carboxymethyl cellulose contents in Examples 9, 10, 3 and 11 are 1 wt%, 2 wt%, 3 wt% and 4 wt%, respectively, increasing gradually, and the others are the same. Figure 6 The relationship between the viscosity and shear rate of the emulsions of these examples is shown. Figure 7 The storage modulus and loss modulus of these example emulsions under shear stress sweep are shown. Figure 6 , Figure 7 The CMC in it stands for carboxymethyl cellulose.

[0136] In Examples 12, 3, 13 and 14, the oil-water ratios are 1:2, 1:3, 1:4 and 1:5 respectively, and the oil specific gravity decreases gradually, while the others are the same. Figure 8 The relationship between the viscosity and shear rate of the emulsions of these examples is shown. Fig. 9 The storage modulus and loss modulus of these example emulsions under shear stress sweep are shown. Figure 8 , Fig. 9 The O:W in the formula represents the oil-water ratio.

[0137] from Figures 4 to 9It can be seen that the rheological properties of Pickering emulsion will change by adjusting the amount of montmorillonite, the amount of carboxymethyl cellulose and the oil-water ratio. Figure 4 , Figure 6 , Figure 8 As shown in the figure, all the Pickering emulsions have shear thinning behavior, and the viscosity decreases rapidly with the increase of shear rate. This property can ensure that the emulsion can be extruded smoothly in the subsequent 3D printing process without blocking the needle. And from the comparison of each figure, it can be seen that with the increase of montmorillonite dosage, carboxymethyl cellulose, and oil-water ratio, the initial viscosity of Pickering emulsion increases continuously, reaching a maximum of more than 10 3 Pa·s. Its initial high viscosity can ensure the shaping ability of the emulsion.

[0138] At the same time, the emulsion also has obvious thixotropy, such as Figure 5 , Figure 7 , Fig. 9 As shown, under low shear stress, the storage modulus G' is significantly greater than the loss modulus G". The stress at the first intersection of the storage modulus and loss modulus curves is the yield stress. With the increase in the amount of montmorillonite, the increase in carboxymethyl cellulose, and the increase in the oil-water ratio, the modulus value of the Pickering emulsion increases, and the yield stress also increases. These characteristics indicate that the Pickering emulsion has a certain ability to resist external shear force, that is, deformation, and has self-supporting properties. Subsequently, the ink of the Pickering emulsion can maintain the integrity of the ink structure after being squeezed out of the needle to prevent deformation and collapse.

[0139] Embodiment of pipeline self-repairing concrete component

[0140] The Pickering emulsion of Example 3 is used as printing ink to prepare pipeline self-repairing concrete parts, and the steps are as follows Fig.10 As shown in the figure, the 3D model is designed and converted into g-code, and then the 3D printer is controlled to print inside the cement slurry. The cement is ordinary Portland cement (PO 42.5), and the water-cement ratio is 0.4 to prepare the slurry. The needle of the 3D printer is inserted into the cement matrix slurry for 3D printing to form a pipeline template.

[0141] Then the hydration treatment is carried out. In the early stage of cement hydration, the hydration heat temperature exceeds the solid-liquid phase transition temperature of methyl palmitate (28°C), the cement hydration continuously absorbs water, the water-in-oil structure of the Pickering emulsion is gradually destroyed, and the methyl palmitate remains in liquid state and penetrates into the surrounding cement matrix. As the hydration progresses to the later stage, the internal temperature of the cement drops, and the methyl palmitate turns into a solid state to form a hydrophobic pipe wall, and the pipe is connected to the outside world. Finally, use clean water to rinse the remaining impurities inside the pipe for 10 minutes, rinse the montmorillonite and carboxymethyl cellulose clean, and obtain the self-repairing concrete parts of the pipe.

[0142] like Fig.11As shown, when constructing the shape of a pipe inside concrete through 3D printing, the size of the pipe can be controlled by adjusting the air pressure, needle movement speed and needle inner diameter to obtain pipe diameters of different sizes, with a minimum of 0.6 mm and a maximum of 3.5 mm.

[0143] In order to verify the hydrophobicity and connectivity of the drain pipe, water was pumped into the pipe from the outside, water was added from one end and discharged from the other end, and the loss rate was verified. It was found that the volume loss rate of the pumped water was less than 2%, indicating that methyl palmitate had hydrophobically modified the cement matrix around the pipe. The internal pipe constructed in this way can be pumped with different types of liquid repair agents from the outside to repair cracks.

[0144] A 40mm*40mm*160mm cement specimen was made, and a single-connected straight-through pipe with a diameter of 2mm was printed in the middle. The 3D printing parameters were: the needle model was 21G (inner diameter 0.51mm), the air pressure was 0.2MPa, and the needle movement speed was 20mm / s. After printing, the hydration reaction was cured for 28 days to obtain a self-repairing concrete pipe. Cracks were generated in the cement specimen through three-point bending loading, and a peristaltic pump was connected to the internal pipe to circulate polyurethane for 10 minutes, and then it was cured for one day. Fig.12 As shown, Fig.12 The left picture shows the state before the crack is repaired, and the right picture shows the state after the crack is repaired. By comparison, it can be seen that the crack gaps are filled and the polyurethane has a repairing effect on the cracks.

[0145] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A Pickering emulsion, Features: It is an oil-in-water emulsion, wherein the aqueous phase includes water and colloidal particles and water-soluble cellulose ether, and the colloidal particles and water-soluble cellulose ether are dispersed in water; and the oil phase includes fatty acid ester; At least part of the colloidal particles and the water-soluble cellulose ether are distributed on the surface of the droplets of the oil phase, wherein hydrogen bonds are formed between the colloidal particles and the water-soluble cellulose ether and / or both carry negative charges.

2. The Pickering emulsion according to claim 1, Features: The water-soluble cellulose ether includes at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose and ethyl cellulose; And / or, the concentration of the water-soluble cellulose ether in the aqueous phase is 0.1 wt% to 4 wt%.

3. The Pickering emulsion according to claim 1 or 2, Features: The contact angle of the colloidal particles is 20° to 25°; And / or, the Dv50 particle size of the colloidal particles may be 1 to 1000 nm; And / or, the colloidal particles include at least one of montmorillonite, kaolin, nano-silica, laponite, and sepiolite; And / or, the concentration of the colloidal particles in the aqueous phase is 1 wt % to 5 wt %.

4. The Pickering emulsion according to claim 1 or 2, Features: The pH value of the aqueous phase is 6 to 8; And / or, the Zeta potential of the aqueous phase is ≤ -20 mV; And / or, the oil-water ratio of the Pickering emulsion is 1:(2-5).

5. The Pickering emulsion according to claim 1 or 2, Features: The solid-liquid phase transition temperature of the fatty acid ester is 25 to 50°C; And / or, the fatty acid ester includes at least one of methyl palmitate, methyl margarate, methyl octadecanoate, methyl eicosate, ethyl hexadecanoate, ethyl heptadecanoate, and ethyl octadecanoate; And / or, the Dv50 particle size of the droplets of the oil phase is 10 to 30 μm.

6. A method for preparing the Pickering emulsion according to any one of claims 1 to 5, It is characterized in that The steps include: The raw materials including the oil phase are added to the solution of the water phase for emulsification.

7. A self-repairing concrete component for pipelines, Features: It comprises a component base and a hydrophobic pipeline, wherein the hydrophobic pipeline is arranged in the component base and communicated with the outside, and the hydrophobic pipeline is formed by solidifying the Pickering emulsion according to any one of claims 1 to 5.

8. The pipeline self-repairing concrete component according to claim 7, Features: The diameter of the drain pipe is 0.6-3.5 mm.

9. A method for preparing a pipeline self-repairing concrete component, It is characterized in that The steps include: Constructing a pipeline template in concrete slurry, wherein the pipeline template is prepared by molding the Pickering emulsion according to any one of claims 1 to 5 or the Pickering emulsion prepared by the preparation method according to claim 6; The concrete slurry containing the pipeline template is subjected to a hydration reaction to obtain a pipeline self-repairing concrete component.

10. The preparation method according to claim 9, Features: The molding process includes a 3D printing process.

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