Polymer mortar with persistent carbon dioxide absorption function and preparation method thereof

Abstract

This invention belongs to the field of green building materials technology, and relates to a polymer mortar with a long-lasting carbon dioxide absorption function and its preparation method. The polymer mortar is mainly made from the following raw materials in parts by weight: 500-800 parts cement, 400-800 parts 10-20 mesh quartz sand, 400-800 parts 20-40 mesh quartz sand, 400-800 parts 40-70 mesh quartz sand, 200-500 parts 70-100 mesh quartz sand, 20-50 parts silica fume, 10-30 parts redispersible latex powder, and 1-5 parts admixtures. An additional 1%-15% of the total mass of the above raw materials is added to an organic amine. The organic amine is a double-terminated primary amine containing silicon-oxygen bonds, prepared by a ring-opening reaction of 1,3,5,7-tetramethylcyclotetrasiloxane to obtain an amino-terminated hydrogen-containing polysiloxane, followed by a hydrosilylation reaction. The organic amines in the polymer mortar of this invention have double-terminated amino groups and contain silicon-oxygen bonds that can firmly bind with the polymer mortar, enabling them to capture large amounts of carbon dioxide continuously.

Description

Technical Field

[0001] This invention belongs to the field of green building materials technology, specifically relating to a polymer mortar with persistent carbon dioxide absorption function and its preparation method. Background Technology

[0002] With the continuous increase in the world's population and people's growing demand for a higher quality of life, global CO2 emissions have increased dramatically, posing a threat to human life systems. Against this backdrop, countries around the world are working together through global agreements to reduce CO2 emissions.

[0003] The building materials industry is a significant high-energy-consuming and high-emission industry in my country, and a key sector for controlling and reducing greenhouse gas emissions. Continuously developing green and low-carbon products is imperative. Despite various emission reduction measures implemented in all stages of cement manufacturing, fossil fuel combustion and carbonate ore decomposition remain the primary sources of carbon emissions. According to life cycle assessment theory, cement carbon emissions exist not only in the production stage but also in transportation, use, service, and waste recycling. Therefore, unavoidable carbon emissions during production should be balanced through proactive carbon capture or sequestration measures in the transportation, application, maintenance, and recycling stages of cement. Given the importance of the cement industry in addressing challenges such as climate change, environmental risks, and energy resource constraints, research on CO2 capture and sequestration technologies based on cement as a material is crucial for promoting the industry's green transformation and high-quality development.

[0004] Carbon sequestration in cement-based materials refers to the capture and fixation of CO2 during the curing or use of cement-based materials. As a mineral-based CO2 sequestration technology, carbon sequestration in cement-based materials can capture and fix CO2 during the cement's use phase, offsetting CO2 emissions from the production phase, thereby reducing the carbon emissions throughout the cement product's life cycle. This represents a new approach in cement-based material research. However, current research in this field, both domestically and internationally, is limited, with most studies focusing on the compression and separation of atmospheric carbon dioxide. Even when CO2 capture technology is applied to building materials, it is mostly through post-impregnation and recoating methods. This method not only has limited CO2 capture capacity and short-term sustainability but also involves cumbersome construction and lacks practical application value.

[0005] Therefore, given the enormous amount of cement used in my country every year, it is necessary to develop cement-based carbon sequestration materials, namely polymer mortars with a long-lasting carbon dioxide absorption function. These materials can capture carbon dioxide before application, reducing the need for secondary construction and aligning with low-carbon emission reduction policies. Summary of the Invention

[0006] In view of the problems and shortcomings of the existing technology, the present invention aims to provide a polymer mortar with persistent carbon dioxide absorption function and its preparation method.

[0007] To achieve the objectives of this invention, the technical solution adopted is as follows:

[0008] This invention provides a polymer mortar with a long-lasting carbon dioxide absorption function. The polymer mortar is mainly made of the following raw materials in parts by weight: 500-800 parts cement, 400-800 parts 10-20 mesh quartz sand, 400-800 parts 20-40 mesh quartz sand, 400-800 parts 40-70 mesh quartz sand, 200-500 parts 70-100 mesh quartz sand, 20-50 parts silica fume, 10-30 parts redispersible latex powder, 1-5 parts admixture, and an additional 1%-15% organic amine by weight of the total mass of the above raw materials.

[0009] The organic amine is a di-terminated primary amine containing silicon-oxygen bonds. An amino-terminated hydrogen-containing polysiloxane intermediate is prepared by ring-opening reaction of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane as a capping agent and 1,3,5,7-tetramethylcyclotetrasiloxane. The intermediate is then reacted with γ-methacryloyloxypropyltrimethoxysilane via a hydrosilylation reaction to obtain the final product.

[0010] The additive is one or more of the following: water-reducing agent, defoamer, and expanding agent.

[0011] Preferably, the molar ratio of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and 1,3,5,7-tetramethylcyclotetrasiloxane is (4-6):1.

[0012] Preferably, the molar ratio of γ-methacryloyloxypropyltrimethoxysilane to amino-terminated hydrogen-containing polysiloxane intermediate is (0.9–1.1):1.

[0013] Preferably, the cement is one or more of the following: fly ash cement 425, fly ash cement 525, slag silicate cement 425, slag silicate cement 525, ordinary silicate cement 425, and ordinary silicate cement 525.

[0014] Preferably, the redispersible latex powder is one or more of ethylene / vinyl acetate copolymer, vinyl acetate / ethylene tert-carbonate copolymer / acrylic acid copolymer.

[0015] The polymer mortar of this invention possesses a persistent carbon dioxide absorption function, and its carbon fixation mechanism is as follows:

[0016] Primary and secondary amines readily react with CO2 to form relatively stable carbamates.

[0017] RNH2 + CO2 → RNH2 + COO - (1)

[0018] In high humidity environments, carbamates undergo partial hydrolysis:

[0019] RNH2+COO - + H2O→HCO3 - +CO3 2- (2)

[0020] In a strongly alkaline environment, HCO3 - It is also difficult to exist, and it generates CO3. 2- .

[0021] CO3 2- + Ca 2+ →CaCO3 (3)

[0022] The present invention also provides a method for preparing the above-mentioned polymer mortar with persistent carbon dioxide absorption function, specifically: cement, 10-20 mesh quartz sand, 20-40 mesh quartz sand, 40-70 mesh quartz sand, 70-100 mesh quartz sand, silica fume, redispersible latex powder, organic amine and additives are mixed in parts by mass and stirred evenly to obtain dry powder mortar, and 10% to 15% of water by mass of dry powder mortar is added and mixed evenly to obtain polymer mortar.

[0023] Preferably, the polymer mortar has a pH value of 12 to 15.

[0024] Preferably, the polymer mortar system c(OH) - The value ranges from 0.01 mol / L to 10 mol / L.

[0025] The organic amine is prepared by the following method:

[0026] S1: The capping agents 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and 1,3,5,7-tetramethylcyclotetrasiloxane (D4H) are added to a reactor equipped with a reflux condenser. A protective gas is introduced, the temperature is raised to 70-90°C, an alkaline catalyst is added, and the reaction is carried out for 7-10 hours to obtain an amino-capped hydrogen-containing polysiloxane intermediate with the structure shown in Formula 1.

[0027]

[0028] S2: Under a protective gas atmosphere, toluene and γ-methacryloxypropyltrimethoxysilane (KH570) are added to a reactor, the temperature is raised to 60-80°C, Karstedt catalyst is added, and then an amino-terminated hydrogen-containing polysiloxane intermediate is added. The reaction is carried out for 0.5-3 hours, and toluene is removed to obtain an organic amine with the structure shown in Formula 2.

[0029]

[0030] Preferably, the alkaline catalyst is one or more of sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) The polymer mortar of the present invention incorporates an organic amine with a special structure, namely a double-terminated primary amine containing silicon-oxygen bonds. The double-terminated amino organic amine molecule has a large volume, which can increase the amount of CO2 fixed and continuously absorb a large amount of CO2 from the air. The silicon-oxygen bonds of the organic amine can form stronger covalent bonds with the polymer mortar, which has an excellent anchoring effect, avoids the loss of organic amine in the later stage, and can continuously capture CO2. In the later stage, the polymer mortar still has excellent CO2 capture function in a high humidity environment.

[0033] (2) In a high humidity environment, the organic amine in the polymer mortar of the present invention captures CO2, which will penetrate into the pores of the mortar and react with the hydration product Ca(OH)2 inside the cement mortar, and then be converted into a large amount of CaCO3. This allows the organic amine polymer mortar to fix CO2. At the same time, the solidified product CaCO3 is insoluble in water and plays a role in filling the cement pores and enhancing the mechanical properties. Attached Figure Description

[0034] Figure 1 TG and DTG curves of polymer mortar (blank control 2);

[0035] Figure 2 Example 5: TG and DTG curves of polymer mortar. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0037] Example 1: Preparation of a bi-terminated primary amine containing silicon-oxygen bonds

[0038] The preparation of a diterminated primary amine containing silicon-oxygen bonds includes the following steps:

[0039] S1: Preparation of amino-terminated hydrogen-containing polysiloxane intermediates by ring-opening reaction of D4H

[0040] The capping agents 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and 1,3,5,7-tetramethylcyclotetrasiloxane (D4H) were added to a reaction vessel equipped with a reflux condenser at a molar ratio of 4.5:1. Nitrogen gas was purged throughout the process for protection. The temperature was raised to 75°C, and potassium hydroxide catalyst was added. The reaction was carried out for 10 hours to obtain an amino-capped hydrogen-containing polysiloxane intermediate, the structure of which is shown in Formula 1.

[0041] S2: Hydrosilylation reaction to prepare the target product

[0042] Under an inert gas atmosphere, toluene and γ-methacryloxypropyltrimethoxysilane (KH570) were added to a reactor, heated to 70°C, and Karstedt catalyst was added. Then, an amino-terminated hydrogen-containing polysiloxane intermediate was added to the reaction vessel. The molar ratio of KH570 to the intermediate was 1:1. The reaction was maintained at this temperature for 1 hour. After the reaction was completed, the solvent toluene was removed to obtain a di-terminated primary amine containing silicon-oxygen bonds, the structure of which is shown in Formula 2.

[0043] Example 2

[0044] A polymer mortar with long-lasting carbon dioxide absorption function is mainly made from the following raw materials in parts by weight:

[0045] 650 parts cement;

[0046] 500 parts of 10-20 mesh quartz sand;

[0047] 400 parts of 20-40 mesh quartz sand;

[0048] 450 parts of 40-70 mesh quartz sand;

[0049] 200 parts of 70-100 mesh quartz sand;

[0050] 25 parts silica fume;

[0051] 15 parts of redispersible latex powder;

[0052] 4 parts of admixture;

[0053] In addition, add 1% organic amine by weight of the total mass of the above raw materials.

[0054] The cement is ordinary Portland 425 cement, the redispersible latex powder is ethylene / vinyl acetate copolymer, the admixture is a water-reducing agent, and the organic amine is a bis-terminated primary amine containing silicon-oxygen bonds prepared in Example 1.

[0055] Preparation method of polymer mortar: Mix the above raw materials evenly to obtain dry powder mortar, add 13% water (by weight of the dry powder mortar) and mix evenly to obtain polymer mortar with long-lasting carbon dioxide absorption function. Take a portion of the mortar to measure the pH value. Pour the remaining mortar into a standard mold and cure it under standard humidity and temperature conditions until final setting. Remove the mold and place it in a carbonization box with a 20% CO2 concentration, and cure it under standard humidity and temperature conditions for 28 days. During this period, relevant performance tests are carried out.

[0056] Example 3

[0057] Example 3 is basically the same as Example 2, except that the amount of organic amine added is 3%.

[0058] Example 4

[0059] Example 4 is basically the same as Example 2, except that the amount of organic amine added is 5%.

[0060] Example 5

[0061] Example 5 is basically the same as Example 2, except that the amount of organic amine added is 7%.

[0062] Example 6

[0063] Example 6 is basically the same as Example 2, except that the amount of organic amine added is 9%.

[0064] Example 7

[0065] Example 7 is basically the same as Example 2, except that the amount of organic amine added is 11%.

[0066] Example 8

[0067] Example 8 is basically the same as Example 2, except that the amount of organic amine added is 12%.

[0068] Example 9

[0069] Example 9 is basically the same as Example 2, except that the amount of organic amine added is 15%.

[0070] Blank control 1

[0071] The blank control 1 and Example 2 have basically the same raw material composition, except that the amount of organic amine added is 0.

[0072] Preparation method of polymer mortar: The above raw materials are stirred evenly to obtain dry powder mortar. Water of 13% by weight of the dry powder mortar is added and mixed evenly to obtain polymer mortar. A portion of the mortar is taken to measure the pH value. The remaining mortar is poured into a standard mold and cured for 28 days under standard humidity and temperature conditions as a blank control group 1.

[0073] Blank control 2

[0074] Blank Control 2 has essentially the same raw material composition as Example 2, except that the amount of organic amine added is 0. The preparation method of the polymer mortar is the same as that of Example 2.

[0075] (I) Mechanical property testing

[0076] The mechanical properties of the polymer mortars prepared in Examples 2-9 were tested, and the results are shown in Table 1.

[0077] Table 1. Test results of mechanical properties of polymer mortars in Examples 2-9

[0078]

[0079] A comparison of Examples 2-9 with Blank Control 1 shows that as the amount of organic amine added increases, the pH value of each example gradually increases, while the initial and final setting times become shorter. This is mainly because the higher alkali content accelerates the early hydration rate of cement and the formation of potassium gypsum, becoming an important reason for cement flash setting. Organic amines affect the mechanical properties of polymer mortar, with the most significant impact on the initial setting time (workability). When the organic amine content reaches 10% or more, the initial setting time is too short (21 min), making it almost impossible to work. Simultaneously, the higher alkali content slightly increases the strength of cement before 7 days, but reduces its later and long-term strength. Compared with Blank Control 1, Blank Control 2 shows a greater loss in flexural and compressive strength. This is mainly because, in a high-concentration CO2 environment, the Blank Control 2 specimen does not contain organic amines that capture carbon dioxide, and therefore cannot provide an alkaline environment for the hydration system for a long time. Thus, CO2 enters the mortar block through the pores of the polymer mortar and reacts with the Ca in the specimen. 2+ The organic amine disrupts the hydration gel system (cement carbonation), severely affecting the mechanical properties of the specimens. Compared to blank control 2, Examples 2-9 exhibit better mechanical properties because the organic amine can capture CO2 and react with Ca(OH)2 produced during cement hydration to generate water-insoluble CaCO3. This not only fixes carbon dioxide but also fills the pores within the cement, enhancing its mechanical properties.

[0080] (II) Carbon fixation test

[0081] CO2 fixation can be quantitatively characterized using a thermogravimetric analyzer (TGA) through thermogravimetric curves. The method is as follows: Thermogravimetric analysis was performed on the polymer mortar prepared in blank control group 2 and Example 5 to obtain TG and DTG curves. The TG and DTG curves of blank control group 2 are shown below. Figure 1 The TG and DTG curves of Example 5 are shown below. Figure 2 .

[0082] Depend on Figure 1 , Figure 2 The comparison shows that the DTG curves of the samples all exhibit two rapid mass loss processes. During the 0–120℃ stage, 1, Figure 1 In the blank group, this stage represents the loss of amorphous moisture in the material; Figure 2 In stage 1, the weight loss peak is relatively large. The mass loss in this stage mainly consists of two parts: the release of CO2 captured by the organic amine and the volatilization of amorphous water. In the 150–350℃ stage, based on the physicochemical properties of the organic amine (the boiling point of the self-made organic amine with a special structure is 227.8℃), it can be inferred that this stage is caused by the volatilization of the organic amine itself, and this part of the mass loss accounts for a small proportion. In stage 2 (600–800℃), CaCO3 begins to decompose into CaO and CO2, and the DTG curve shows a rapid mass loss in this stage. The graph shows that, excluding the mass loss in the first stage, the amount of CO2 decomposed from CaCO3 after carbon fixation with organic amine-coated cement mortar is greater than that after carbon fixation with the reference mortar, indicating that the polymer mortar carbon fixation produces more CaCO3 than the blank group mortar. Therefore, the quantitative value of carbon fixation by the polymer mortar can be obtained by comparing the two values.

[0083] Carbon fixation tests were conducted on the polymer mortars prepared in Examples 2-9 using the above method, and the results are shown in Table 2. The formula for calculating the net CaCO3 loss is as follows:

[0084]

[0085] The formula for calculating the amount of CO2 fixed is as follows:

[0086] Ca(OH)₂ + CO₂ = CaCO₃ + H₂O 44 100

[0088] M(CO2)M(CaCO3)

[0089] M(CO2) = 0.44 × M(CaCO3)

[0090] Under atmospheric conditions, we assume that the test block does not carbonize in a short period of time, that is, it does not absorb carbon dioxide, and the net loss of CaCO3 in blank group 1 is considered to be 0.

[0091] Without organic amines, the amount of carbon dioxide fixed at 20% carbonization acceleration was: Blank group 2: 0.44×(2.77-0)=1.22; Example 5, the amount of carbon dioxide fixed by organic amines was: 0.44×(57.59-2.77)=24.12.

[0092] Table 2. Carbon fixation test results of polymer mortars in Examples 2-9

[0093]

[0094] As shown in Table 2, the amount of fixed CO2 gradually increases with the increase of organic amine content. The blank control 2, which did not contain organic amine, had very little fixed CO2, meaning it only had carbonization. Based on the test results in Table 1, Example 5 is the most preferred solution among the examples presented in this invention to obtain a polymer mortar that balances workability, mechanical properties, and carbon fixation.

[0095] Comparative Example 1

[0096] The difference from Example 5 is that the organic amine used is pentamethylenediamine.

[0097] Comparative Example 2

[0098] The difference from Example 5 is that the organic amine used is hexamethylenediamine.

[0099] Comparative Example 3

[0100] The difference from Example 5 is that the organic amine used is heptanediamine.

[0101] Comparative Example 4

[0102] The difference from Example 5 is that the organic amine used is octanediamine.

[0103] Comparative Example 5

[0104] The difference from Example 5 is that nonadiamine is used as the organic amine.

[0105] Comparative Example 6

[0106] The difference from Example 5 is that melamine is used as the organic amine.

[0107] The polymer mortars prepared with different organic amines in Comparative Examples 1-6 and Example 5 were tested for mechanical properties and carbon fixation. The results are shown in Table 3. The formula for calculating the CaCO3 fixation rate is as follows:

[0108]

[0109] Table 3 Performance test results of polymer mortars in Comparative Examples 1–6

[0110]

[0111] As can be seen from the comparison of Comparative Examples 1-6 and Example 5 in Table 3, the initial setting time of the polymer mortar in Comparative Examples 1-5 gradually increased with the increase of aliphatic diamine chain segments, which conforms to the rule that the alkalinity of aliphatic diamine decreases with the increase of chain segment length after water solubility. The carbon fixation amount decreased accordingly after 28 days. From the change in the growth rate of CO2 fixation, it can be seen that aliphatic diamines with shorter chain segments are easily precipitated from the pores of polymer mortar in a high-humidity environment, that is, the durability is poor. Comparative Example 6 uses large-volume melamine as organic amine. Although the growth rate of CO2 fixation increases, melamine has poor solubility in water and it is difficult to provide a large alkaline environment. It is greatly affected by carbonization and has a large loss of mechanical properties. Example 5 of this invention uses the primary amine containing silicon-oxygen bonds prepared in Example 1 for polymer mortar, which has good durability and can still fix carbon well after 28 days, thus simultaneously taking into account carbon fixation performance and mechanical properties. This is because the double-terminated amino organic amine prepared in Example 1 has a larger molecular volume, which increases the amount of CO2 fixed. Simultaneously, the introduction of silicon-oxygen bonds allows it to form Si-O-Si covalent bonds with the polymer mortar, resulting in more reliable anchoring and preventing the loss of organic amine later on. This allows for continuous CO2 capture, and the polymer mortar retains excellent CO2 capture capabilities even in high humidity environments. Furthermore, the organic amine captures CO2 and reacts with Ca(OH)2 generated during cement hydration to form water-insoluble CaCO3. This not only fixes carbon dioxide but also fills the internal pores of the cement, enhancing its mechanical properties.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Those skilled in the art can modify or make equivalent substitutions to the technical solutions of the present invention based on the concept of the present invention, without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polymer mortar with persistent carbon dioxide absorption function, characterized in that, The polymer mortar is mainly made of the following raw materials in parts by weight: 500-800 parts cement, 400-800 parts 10-20 mesh quartz sand, 400-800 parts 20-40 mesh quartz sand, 400-800 parts 40-70 mesh quartz sand, 200-500 parts 70-100 mesh quartz sand, 20-50 parts silica fume, 10-30 parts redispersible latex powder, 1-5 parts admixtures, and an additional 1%-15% organic amine by weight of the total mass of the above raw materials. The organic amine is a di-terminated primary amine containing siloxane bonds. It is prepared by using 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane as a capping agent and undergoing a ring-opening reaction with 1,3,5,7-tetramethylcyclotetrasiloxane to obtain an amino-terminated hydrogen-containing polysiloxane intermediate. The intermediate is then subjected to a hydrosilylation reaction with γ-methacryloyloxypropyltrimethoxysilane to obtain the final product. The additive is one or more of the following: water-reducing agent, defoamer, and expanding agent.

2. The polymer mortar according to claim 1, characterized in that, The molar ratio of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and 1,3,5,7-tetramethylcyclotetrasiloxane is (4-6):

1.

3. The polymer mortar according to claim 2, characterized in that, The molar ratio of the γ-methacryloxypropyltrimethoxysilane to the hydrogen-containing polysiloxane intermediate is (0.9–1.1):

1.

4. The polymer mortar according to claim 1, characterized in that, The cement is one or more of the following: fly ash cement 425, fly ash cement 525, slag silicate cement 425, slag silicate cement 525, ordinary silicate cement 425, and ordinary silicate cement 525.

5. The polymer mortar according to claim 1, characterized in that, The redispersible latex powder is one or more of ethylene / vinyl acetate copolymer, vinyl acetate / ethylene tert-carbonate copolymer / acrylic acid copolymer.

6. The method for preparing polymer mortar with persistent carbon dioxide absorption function according to any one of claims 1-5, characterized in that, Cement, 10-20 mesh quartz sand, 20-40 mesh quartz sand, 40-70 mesh quartz sand, 70-100 mesh quartz sand, silica fume, redispersible latex powder, additives and organic amines are mixed in parts by weight and stirred evenly to obtain dry powder mortar. 10% to 15% of water by weight of dry powder mortar is added and mixed evenly to obtain polymer mortar.

7. The method for preparing polymer mortar according to claim 6, characterized in that, The organic amine is prepared by the following method: S1: The capping agents 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and 1,3,5,7-tetramethylcyclotetrasiloxane are added to the reactor, a protective gas is introduced, the temperature is raised to 70-90℃, an alkaline catalyst is added, and the reaction is carried out for 7-10 hours to obtain an amino-capped hydrogen-containing polysiloxane intermediate; S2: Under a protective gas atmosphere, toluene and γ-methacryloxypropyltrimethoxysilane are added to the reactor, the temperature is raised to 60-80°C, Karstedt catalyst is added, and then an amino-terminated hydrogen-containing polysiloxane intermediate is added. The reaction is carried out for 0.5-3 hours, and toluene is removed to obtain an organic amine.

8. The method for preparing polymer mortar according to claim 7, characterized in that, The alkaline catalyst is one or more of sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide.

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