CN115925447A - Modifier with wettability responding to pH and using method thereof - Google Patents

Abstract

The invention discloses a modifier whose wettability responds to pH, which comprises the following substances in parts by weight: 50-70 parts of alkyl dicarboxylic acid, 30-50 parts of saturated fatty acid, 1900-2000 parts of absolute ethanol, Modifiers are capable of converting cement-based materials from hydrophilic to hydrophobic. The invention also discloses two usage methods of the modifying agent whose wettability responds to pH. The invention facilitates water entry and cement hydration in the early maintenance process, does not leave water stains on the horizontal surface of the sample, and can meet the requirements of anti-contamination and anti-water intrusion in the later service stage; the raw materials are green and environmentally friendly, non-toxic and harmless, and low cost Low; the preparation method is simple to operate and requires low equipment; the substrate used is cement-based materials, which expands the application of stimuli-responsive surfaces; the wettability of pH-responsive surfaces can be prepared quickly, and the prepared hydrophilic-hydrophobic adjustable cement-based materials show a strong Hydrophilic character, the service phase turns hydrophobic after treatment with an acidic solution.

Description

A kind of modifier of wettability to pH response and using method thereof

technical field

The invention relates to a modifier and its usage, in particular to a modifier whose wettability responds to pH and its usage method.

Background technique

In the natural environment, in response to complex and diverse external changes, animals or plants will selectively evolve interface molecules and build specific chemical structures to obtain various wettability and variable functional surfaces. This has inspired researchers to develop new materials, such as imitating the superhydrophobic surface structure of plants such as lotus leaves to prepare superhydrophobic new materials, imitating the responsive biological interface in the natural environment to prepare responsive polymers and superwetting materials that can interact with external stimuli. wet surface. Utilizing responsive polymers and superwetting surfaces enables the preparation of smart responsive materials that respond intelligently to stimuli and are widely used in various emerging fields.

At present, the research on preparing wettable stimulus-responsive surfaces mainly focuses on substrates such as sponges, fabrics, metals, and crystals, and there is still a lack of related explorations on the realization of wettability-stimuli-responsive functions on cement-based material substrates. In the field of cement-based materials, (super) hydrophobic cement-based materials are mainly obtained by doping low surface energy functional components or preparing coatings. However, the existing methods can only obtain the surface of cement-based materials with a single (super) hydrophobic function, which is not conducive to the entry of water and cement hydration in the early curing process, and it is easy to retain water stains on the horizontal surface of the sample. Contamination, anti-water intrusion requirements.

Contents of the invention

Purpose of the invention: In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a modifier that reduces the adverse effect of hydrophobicity in the early curing stage of cement-based materials, rapid preparation, and wettability to pH response. Another purpose is to provide two convenient and practical usage methods of the wettability-pH responsive modifying agent that meets the requirements of anti-contamination and anti-water intrusion.

Technical solution: A modifier of wettability responsive to pH according to the present invention, comprising the following parts by weight: 50-70 parts of alkyl dicarboxylic acid, 30-50 parts of saturated fatty acid, 1900 parts of absolute ethanol ~2000 parts, the modifier can change the cement-based material from hydrophilic to hydrophobic.

Further, the alkyl dicarboxylic acid is any one of suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and tridecanedioic acid.

Further, the saturated fatty acid is any one of capric acid, lauric acid, myristic acid, palmitic acid, pearlescent fatty acid, and stearic acid.

The first method of using the above-mentioned wettability-responsive modifier for pH, i.e. the dipping method, comprises the following steps:

Step 1, adding saturated fatty acid and alkyl dicarboxylic acid to absolute ethanol according to the ratio of parts by weight, and stirring until completely dissolved to obtain a modifier;

Step 2: Mix and stir water and Portland cement evenly, pour the slurry into a rubber mold for molding, remove the mold, and maintain in the natural environment;

Step 3: Take out the product obtained in Step 2, use deionized water to clean the surface, then use absolute ethanol to clean, and dry the cleaned cement-based material;

Step 4, immerse the product obtained in Step 3 in the modifier prepared in Step 2, take out the treated cement-based material substrate, wash with absolute ethanol, and dry to obtain the cement-based material.

Further, in step 2, the water-cement ratio of water and Portland cement is 0.3-0.4, and the curing time is 7-8 days.

Further, in step 3, the drying temperature is 45-50° C., and the drying time is 6-8 hours.

Further, in step 4, the immersion time is 6-8 hours, the drying temperature is 45-55° C., and the drying time is 5-7 hours.

The second method of using the above-mentioned wettability to pH-responsive modifier, that is, the internal mixing method, comprises the following steps:

Step 1, react saturated fatty acid and alkyl dicarboxylic acid with excess hydroxide salt solution according to the ratio of parts by weight, obtain saturated fatty acid salt and alkyl dicarboxylic acid salt after filtering and drying;

Step 2, controlling the mass percentage of the alkyl dicarboxylate in the mixed components to be 50% to 70%, then adding water at 35 to 45°C, and stirring until completely dissolved to obtain the additive;

Step 3: Mix and stir the additives, water, and Portland cement evenly, pour the slurry into a rubber mold for molding, remove the mold, and maintain in the natural environment;

Step 4, after curing, rinse the cement sample with hydrochloric acid or sulfuric acid solution with a pH value of 4-6, and dry it at 40-50° C., so that the cement-based material changes from hydrophilic to hydrophobic.

Further, in step three, the water-cement ratio of water and portland cement is 0.3-0.4, and the curing time is 7-8 days.

Preparation principle: According to the surface characteristics of cement-based materials such as strong hydrophilicity and rich hydroxyl groups, the carboxylate at one end of saturated fatty acid is used to achieve grafting, and the methyl group at the other end has a lower surface energy to achieve hydrophobic function; The carboxylate at one end of the base dicarboxylic acid is grafted, and the carboxylate at the other end will deprotonate at high pH and become more hydrophilic to achieve the responsiveness to pH. And by preparing saturated fatty acid and alkyl dicarboxylic acid into corresponding organic acid salts, so as to be dissolved in water and realize internal doping in cement-based materials. Compared with the impregnation method, which utilizes physical adsorption such as hydrogen bonding between the m-carboxylic acid functional group and the cement-based material, the durability of the modification effect of the internal mixing method is better.

Beneficial effects: compared with the prior art, the present invention has the following remarkable features:

1. It is convenient for water entry and cement hydration in the early maintenance process, and will not leave water stains on the horizontal surface of the sample, which can meet the requirements of anti-contamination and anti-water intrusion in the later service stage;

2. The raw materials are green and environmentally friendly, non-toxic and harmless, and the cost is low; the preparation method is simple to operate, and the equipment requirements are low;

3. The substrate used is cement-based materials, which expands the application of stimuli-responsive surfaces in the field of cement-based materials;

4. The prepared wettability-response modifier to pH can quickly prepare a wettability pH-response surface on the cement-based material base, and the prepared hydrophilic-hydrophobic adjustable cement-based material exhibits hydrophilic characteristics in the early maintenance stage , the service phase turns hydrophobic after treatment with an acidic solution.

Description of drawings

Fig. 1 is the wetting diagram of the surface droplet of modified cement-based material latent prepared by dipping method of the present invention;

Fig. 2 is the change diagram of the surface contact angle of the modified cement-based material prepared by the dipping method of the present invention;

Fig. 3 is that the surface contact angle of the modified cement-based material prepared by the dipping method of the present invention varies with the pH value of the solution;

Fig. 4 is the variation diagram of the surface contact angle of the modified cement-based material prepared by the present invention's internal mixing method with the dosage;

Fig. 5 is the surface wettability transition diagram of the modified cement-based material prepared by the internal mixing method of the present invention.

Detailed ways

Example 1

A method for using a wettability modifier responsive to pH, comprising the following steps:

Step 1, 70 parts of saturated fatty acid and 30 parts of alkyl dicarboxylic acid are placed in the container, the alkyl dicarboxylic acid is dodecanedioic acid, the saturated fatty acid is lauric acid, and 1900 parts of absolute ethanol is added to control the alkanes. The mass percentage of base dicarboxylic acid in mixing component (saturated fatty acid, saturated fatty acid) is 30%, stirs until mixing component dissolves completely in ethanol, obtains the modifier that mass fraction is 5wt%;

Step 2: Mix water and Portland cement at a water-cement ratio of 0.4 and stir evenly, pour the slurry into a rubber mold for molding, remove the mold after 1 day, and maintain it in a natural environment for 7 days;

Step 3: Take out the product obtained in Step 2, wash the surface with deionized water, and then use absolute ethanol to clean, and place the cleaned cement-based material in a drying oven for 6 hours at 50°C;

Step 4, immerse the product obtained in Step 3 in the modifier prepared in Step 2, soak for 6 hours, take out the treated cement-based material substrate, clean it with absolute ethanol, and dry it in a drying oven at 50°C for 6 hours. A cement-based material is obtained.

Example 2

A method for using a wettability modifier responsive to pH, comprising the following steps:

Step 1, 50 parts of saturated fatty acid and 50 parts of alkyl dicarboxylic acid are placed in the container, the alkyl dicarboxylic acid is dodecanedioic acid, the saturated fatty acid is lauric acid, and 1900 parts of absolute ethanol is added to control the alkanes. The mass percentage of base dicarboxylic acid in mixing component (saturated fatty acid, saturated fatty acid) is 50%, stirs until mixing component dissolves completely in ethanol, obtains the modifier that mass fraction is 5wt%;

Step 2: Mix water and Portland cement at a water-cement ratio of 0.4 and stir evenly, pour the slurry into a rubber mold for molding, remove the mold after 1 day, and maintain it in a natural environment for 7 days;

Step 3: Take out the product obtained in Step 2, wash the surface with deionized water, and then use absolute ethanol to clean, and place the cleaned cement-based material in a drying oven for 6 hours at 50°C;

Step 4, immerse the product obtained in Step 3 in the modifier prepared in Step 2, soak for 6 hours, take out the treated cement-based material substrate, clean it with absolute ethanol, and dry it in a drying oven at 50°C for 6 hours. A cement-based material is obtained.

Example 3

A method for using a wettability modifier responsive to pH, comprising the following steps:

Step 1, 30 parts of saturated fatty acid and 70 parts of alkyl dicarboxylic acid are placed in the container, the alkyl dicarboxylic acid is dodecanedioic acid, the saturated fatty acid is lauric acid, and 1900 parts of absolute ethanol is added to control the alkanes. The mass percentage of base dicarboxylic acid in mixing component (saturated fatty acid, saturated fatty acid) is 70%, stirs until mixing component dissolves completely in ethanol, obtains the modifier that mass fraction is 5wt%;

Step 2: Mix water and Portland cement at a water-cement ratio of 0.4 and stir evenly, pour the slurry into a rubber mold for molding, remove the mold after 1 day, and maintain it in a natural environment for 7 days;

Step 3: Take out the product obtained in Step 2, wash the surface with deionized water, and then use absolute ethanol to clean, and place the cleaned cement-based material in a drying oven for 6 hours at 50°C;

Step 4, immerse the product obtained in Step 3 in the modifier prepared in Step 2, soak for 6 hours, take out the treated cement-based material substrate, clean it with absolute ethanol, and dry it in a drying oven at 50°C for 6 hours. A cement-based material is obtained.

Use sodium hydroxide to prepare alkaline liquids with pH=7 and pH=13, use a dropper to absorb the two liquids, and drop them respectively on the surface of the cement-based material treated with the modifier. The wetting conditions of droplets with different pH values on the surface are shown in Figure 1. The surface of the modified cement-based material substrate has good hydrophobic characteristics for pH=7 droplets, and there is a "silver mirror phenomenon"; while for pH=13 droplets It is hydrophilic, and the droplets quickly wet and spread on the surface.

Comparative example 1

The rest of the steps of this comparative example are all the same as in Example 1, and the difference is only: in step one, 100 parts of saturated fatty acids and 0 parts of alkyl dicarboxylic acid, that is, control of alkyl dicarboxylic acid in mixed components (saturated fatty acid, saturated fatty acid ) The mass percentage in ) is 0%.

Comparative example 2

The rest of the steps of this comparative example are all the same as in Example 1, the difference is only: in step one, 0 parts of saturated fatty acid, 100 parts of alkyl dicarboxylic acid, that is, control of alkyl dicarboxylic acid in mixed components (saturated fatty acid, saturated fatty acid ) The mass percentage in ) is 100%.

Use sodium hydroxide to prepare the alkaline liquid of pH=13, use deionized water as the neutral liquid of pH=7, test the different mixing groups obtained in Examples 1-3 and Comparative Examples 1-2 with a screen optical contact angle measuring instrument The distribution ratio of the modifier-modified cement-based material surface to the contact angle of two pH droplet, the test droplet size is 5 μL, three sites are tested on each surface, the measurement results are shown in Figure 2. When the proportion of alkyl dicarboxylic acid is 0% and 30%, the contact angle of the cement-based material substrate to pH=7 and pH=13 droplets is not significantly different, and they all remain at 130°-140°, showing hydrophobic characteristics. When the proportion of alkyl dicarboxylic acid is 50% and 70%, the contact angle of the cement-based material substrate surface to the pH=7 and pH=13 droplets is significantly different, and the contact angle to the pH=7 droplet is 115° ~135°, showing hydrophobic characteristics, while the contact angle for pH=13 droplets is below 50°, showing hydrophilic characteristics. When the proportion of alkyl dicarboxylic acid is 100%, there is no significant difference in the contact angle of the cement-based material substrate to the droplet of pH=7 and pH=13, both of which remain about 20°. When the proportion of alkyl dicarboxylic acid is 70%, the contact angle difference between the two droplets is the largest, which is 101°. When the pH of the solution is <7, the contact angle is the same as that at pH=7.

Example 4

A method for using a wettability modifier responsive to pH, comprising the following steps:

Step 1, 40 parts of saturated fatty acid and 60 parts of alkyl dicarboxylic acid are placed in the container, the alkyl dicarboxylic acid is suberic acid, the saturated fatty acid is capric acid, and 2000 parts of absolute ethanol is added to control the amount of alkyl dicarboxylic acid. The mass percent of carboxylic acid in the mixing component is 60%, and stirring is until the mixing component is completely dissolved in ethanol, and the modifier obtained with a mass fraction of 4.8wt%;

Step 2: Mix water and portland cement at a water-cement ratio of 0.3 and stir evenly, pour the slurry into a rubber mold for molding, remove the mold after 1 day, and perform curing in a natural environment for 8 days;

Step 3: Take out the product obtained in Step 2, wash the surface with deionized water, and then use absolute ethanol to clean, and place the cleaned cement-based material in a drying oven for 8 hours at 45°C;

Step 4, immerse the obtained product of Step 3 in the modifier prepared in Step 2, soak for 8 hours, take out the treated cement-based material substrate, clean it with absolute ethanol, and dry it in a drying oven at 45°C for 7 hours. A cement-based material is obtained.

The alkyl dicarboxylic acid in this embodiment can be replaced by any one of suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, saturated The fatty acid may be replaced by any one of capric acid, lauric acid, myristic acid, palmitic acid, pearlescent fatty acid, and stearic acid.

Example 5

A method for using a wettability modifier responsive to pH, comprising the following steps:

Step 1, 60 parts of saturated fatty acid and 40 parts of alkyl dicarboxylic acid are placed in container, and alkyl dicarboxylic acid is tridecanedioic acid, and saturated fatty acid is stearic acid, adds 2000 parts of dehydrated alcohol, promptly control The mass percentage of alkyl dicarboxylic acid in the mixing component is 40%, and stirring is until the mixing component is completely dissolved in ethanol, and the modifier obtained with a mass fraction of 5wt%;

Step 2: Mix water and portland cement at a water-cement ratio of 0.3 and stir evenly, pour the slurry into a rubber mold for molding, remove the mold after 1 day, and perform curing in a natural environment for 8 days;

Step 3: Take out the product obtained in Step 2, wash the surface with deionized water, and then use absolute ethanol to clean, and place the cleaned cement-based material in a drying oven for 8 hours at 45°C;

Step 4, immerse the obtained product of Step 3 in the modifier prepared in Step 2, and immerse it for 8 hours, take out the treated cement-based material substrate, clean it with absolute ethanol, and dry it in a drying oven at 55°C for 5 hours. A cement-based material is obtained.

Example 6

Refer to the method of Example 1 to prepare a cement slurry sample and perform impregnation treatment to obtain a cement-based material with a wettability pH intelligent response function on the surface. Use sodium hydroxide to prepare alkaline liquids with pH=8, 9, 10, 11, 12, and 13, use deionized water as a neutral liquid with pH=7, and use hydrochloric acid to prepare acidic liquids with pH=3 and 5, refer to the implementation The method in Example 1 was used to test the contact angle of the cement-based material surface treated with the modifier to droplets with different pH values.

The measurement results are shown in Figure 3, the surface wettability of the cement-based material substrate of the 70% alkyl dicarboxylic acid group has a stimulus response ability to the pH value. When the droplet pH value is less than or equal to 7, the contact angle is above 135°, and the surface appears hydrophobic; when the droplet pH value is greater than 7, the surface contact angle gradually decreases; when the pH=12, the contact angle is 22°, and the surface appears hydrophobic. Hydrophilic. The 0% alkyl dicarboxylic acid group always maintains a contact angle above 130°, and the 100% alkyl dicarboxylic acid group maintains a contact angle below 25°.

Example 7

A method for using a wettability modifier responsive to pH, comprising the following steps:

Step 1, reacting saturated fatty acid and alkyl dicarboxylic acid with excess hydroxide salt solution, obtaining saturated fatty acid salt and alkyl dicarboxylic acid salt after filtering and drying;

Step 2, weigh saturated fatty acid salt and alkyl dicarboxylate in proportion and place them in the container, control the mass percentage of alkyl dicarboxylate in the mixed components to be 50%, then add water at 35°C and stir until completely dissolved to obtain the additive;

Step 3: Mix and stir the additives, water, and Portland cement evenly, the water-cement ratio is 0.3, pour the slurry into a rubber mold for molding, remove the mold after 1 day, and maintain it in a natural environment for 7 days;

Step 4: After curing, rinse the cement sample with HCl solution with a pH value of 4, and dry it at 40° C., so that the cement-based material changes from hydrophilic to hydrophobic.

In this embodiment, the alkyl dicarboxylic acid is any one of suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and tridecanedioic acid, and the saturated fatty acid is decanedioic acid. Any one of acid, lauric acid, myristic acid, palmitic acid, pearlescent acid, stearic acid.

Example 8

A method for using a wettability modifier responsive to pH, comprising the following steps:

Step 1, reacting saturated fatty acid and alkyl dicarboxylic acid with excess hydroxide salt solution, obtaining saturated fatty acid salt and alkyl dicarboxylic acid salt after filtering and drying;

Step 2, weigh the saturated fatty acid salt and the alkyl dicarboxylate in proportion and place them in the container, control the mass percentage of the alkyl dicarboxylate in the mixed components to be 70%, then add water at 45°C, and stir until completely dissolved to obtain the additive;

Step 3: Mix and stir additives, water, and Portland cement evenly. The water-cement ratio is 0.4. Pour the slurry into a rubber mold for molding. After 1 day, the mold is removed, and it is maintained in a natural environment for 8 days;

Step 4: After curing, rinse the cement sample with a sulfuric acid solution with a pH value of 5, and dry it at 45° C., so that the cement-based material changes from hydrophilic to hydrophobic.

In this embodiment, the alkyl dicarboxylic acid is any one of suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and tridecanedioic acid, and the saturated fatty acid is decanedioic acid. Any one of acid, lauric acid, myristic acid, palmitic acid, pearlescent acid, stearic acid.

Example 9

A method for using a wettability modifier responsive to pH, comprising the following steps:

Step 1, reacting saturated fatty acid and alkyl dicarboxylic acid with excess hydroxide salt solution, obtaining saturated fatty acid salt and alkyl dicarboxylic acid salt after filtering and drying;

Step 2, weigh the saturated fatty acid salt and the alkyl dicarboxylate in proportion and put them in the container, control the mass percentage of the alkyl dicarboxylate in the mixed component to be 60%, then add water at 40°C and stir until completely dissolved to obtain the additive;

Step 3: Mix and stir the additives, water, and Portland cement evenly, the water-cement ratio is 0.3, pour the slurry into a rubber mold for molding, remove the mold after 1 day, and maintain it in a natural environment for 7 days;

Step 4: After curing, rinse the cement sample with a hydrochloric acid solution with a pH value of 6, and dry it at 45° C., so that the cement-based material changes from hydrophilic to hydrophobic.

In this embodiment, the alkyl dicarboxylic acid is any one of suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and tridecanedioic acid, and the saturated fatty acid is decanedioic acid. Any one of acid, lauric acid, myristic acid, palmitic acid, pearlescent acid, stearic acid.

Example 10

A method for using a wettability modifier responsive to pH, comprising the following steps:

Step 1, reacting saturated fatty acid and alkyl dicarboxylic acid with excess hydroxide salt solution, obtaining saturated fatty acid salt and alkyl dicarboxylic acid salt after filtering and drying;

Step 2, take saturated fatty acid salt and alkyl dicarboxylate in proportion and place it in the container, control the mass percentage of alkyl dicarboxylate in the mixed component to be 0%, 70%, 100%, and then Add water at 40°C and stir until completely dissolved to obtain the additive;

Step 3: Mix and stir the additive, water, and Portland cement evenly, the water-cement ratio is 0.4, and the mixed components account for 0%, 0.5%, 1.0%, 1.5%, and 2.0% of the amount of the cementitious material. Pour the slurry into a rubber mold for molding, remove the mold after 1 day, and maintain it in a natural environment for 7 days;

Step 4: After curing, rinse the cement sample with a hydrochloric acid solution with a pH value of 6, and dry it at 45° C., so that the cement-based material changes from hydrophilic to hydrophobic.

Use a screen optical contact angle measuring instrument to test the contact angle of clear water on the surface of the cement-based material obtained in step 3 of different mixing component ratios. The test droplet size is 5 μL, and three points are tested on each surface. The measurement results are shown in Figure 4. It can be seen that when the proportion of alkyl dicarboxylate in the mixed component is 0%, the contact angle increases with the increase of the content, and finally reaches more than 120°; when the alkyl dicarboxylate in the mixed component When the proportion of alkyl dicarboxylate in the mixed component is 100%, the contact angle shows a trend of slight increase and then a slight decrease, and remains below 50°, showing hydrophilicity; when the proportion of alkyl dicarboxylate in the mixed component is 100%, the contact angle After a slight increase, it decreased rapidly. At higher dosages, the contact angle could not be measured due to strong hydrophilicity.

Example 11

A method for using a wettability modifier responsive to pH, comprising the following steps:

Step 1, reacting saturated fatty acid and alkyl dicarboxylic acid with excess hydroxide salt solution, obtaining saturated fatty acid salt and alkyl dicarboxylic acid salt after filtering and drying;

Step 2, weigh the saturated fatty acid salt and the alkyl dicarboxylate in proportion and place them in the container, control the mass percentage of the alkyl dicarboxylate in the mixed components to be 70%, then add water at 40°C, and stir until completely dissolved to obtain the additive;

Step 3: Mix and stir the additive, water, and Portland cement evenly, the water-cement ratio is 0.4, and the mixed components account for 0%, 0.5%, 1.0%, 1.5%, and 2.0% of the amount of the cementitious material. Pour the slurry into a rubber mold for molding, remove the mold after 1 day, and maintain it in a natural environment for 7 days;

Step 4: After curing, rinse the cement sample with a hydrochloric acid solution with a pH value of 5, and dry it at 40° C., so that the cement-based material changes from hydrophilic to hydrophobic.

The contact angle of clear water on the cement-based material surface before and after treatment was tested with a screen optical contact angle measuring instrument. The test droplet size was 5 μL, and three sites were tested on each surface. The measurement results are shown in Figure 5. When the proportion of alkyl dicarboxylate in the mixed components is 70%, the cement-based material is hydrophilic before treatment, and the contact angle remains below 40°; after treatment, the contact angle of the cement-based material increases , when the mixed component accounts for 2.0% of the cementitious material, the contact angle changes from 30° to 120°.

Claims (10)

1. The modifier for wettability response to pH is characterized by comprising the following substances in parts by weight: 30-70 parts of alkyl dicarboxylic acid, 30-70 parts of saturated fatty acid and 1900-2000 parts of absolute ethyl alcohol, wherein the modifier can convert the hydrophilicity of the cement-based material into the hydrophobicity.

2. A wettability-responsive modifier as claimed in claim 1, wherein: the alkyl dicarboxylic acid is any one of suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid and tridecanedioic acid.

3. A wettability modifier for pH response according to claim 1, wherein: the saturated fatty acid is any one of capric acid, lauric acid, myristic acid, palmitic acid, pearlescent fatty acid and stearic acid.

4. A method of using a wettability-pH-responsive modifier according to any one of claims 1 to 3, characterized by the steps of:

step one, adding saturated fatty acid and alkyl dicarboxylic acid into absolute ethyl alcohol according to the weight part ratio, and stirring until the saturated fatty acid and the alkyl dicarboxylic acid are completely dissolved to obtain a modifier;

step two, mixing and stirring water and portland cement uniformly, pouring the slurry into a rubber mold for molding, removing the mold, and maintaining in a natural environment;

step three, taking out the product obtained in the step two, cleaning the surface by using deionized water, cleaning by using absolute ethyl alcohol, and drying the cleaned cement-based material;

and step four, immersing the substance obtained in the step three in the modifier prepared in the step one, taking out the treated cement-based material substrate, cleaning with absolute ethyl alcohol, and drying to obtain the cement-based material.

5. The method of claim 4 for using a wettability-responsive modifier, characterized in that: in the second step, the water cement ratio of water to portland cement is 0.3-0.4, and the curing time is 7-8 days.

6. The method of claim 4 for using a wettability-responsive modifier, characterized in that: in the third step, the drying temperature is 45-50 ℃, and the drying time is 6-8 h.

7. The method of claim 4 for using a wettability-responsive modifier, characterized in that: in the fourth step, the immersion time is 6-8 h, the drying temperature is 45-55 ℃, and the drying time is 5-7 h.

8. The method of claim 4, wherein said modifying agent is selected from the group consisting of: in the fourth step, the drying temperature is 45-55 ℃, and the drying time is 5-7 h.

9. A method of using a wettability-pH-responsive modifier according to any one of claims 1 to 3, comprising the steps of:

reacting saturated fatty acid and alkyl dicarboxylic acid with excessive hydroxide solution according to the weight part ratio, filtering and drying to obtain saturated fatty acid salt and alkyl dicarboxylic acid salt;

step two, controlling the mass percent of the alkyl dicarboxylate in the mixed components to be 50-70%, then adding 35-45 ℃ water, and stirring until the alkyl dicarboxylate is completely dissolved to obtain an additive;

step three, mixing and stirring the additive, water and portland cement uniformly, pouring the slurry into a rubber mold for molding, removing the mold, and maintaining in a natural environment;

and step four, washing the cement sample by using a hydrochloric acid or sulfuric acid solution with the pH value of 4-6 after maintenance, and drying at 40-50 ℃ to change the hydrophilicity of the cement-based material into hydrophobicity.

10. The method of claim 4, wherein said modifying agent is selected from the group consisting of: in the third step, the water cement ratio of water to portland cement is 0.3-0.4, and the curing time is 7-8 days.

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