CN115925447B - Wettability-pH response modifier and application method thereof - Google Patents

Abstract

The invention discloses a wettability-responsive pH modifier, which comprises the following components in parts by weight: 50-70 parts of alkyl dicarboxylic acid, 30-50 parts of saturated fatty acid and 1900-2000 parts of absolute ethyl alcohol, and the modifier can change the hydrophilicity of the cement-based material into hydrophobicity. Two methods of using the wettability-responsive pH modifying agent are also disclosed. The invention is convenient for water entering and cement hydration in the early maintenance process, does not reserve water stains on the horizontal surface of the sample, and can meet the requirements of stain resistance and water invasion resistance in the later service stage; the raw materials are green, environment-friendly, nontoxic and harmless, and the cost is low; the preparation method is simple to operate and has low equipment requirement; the substrate is cement-based material, so that the application of the stimulus response surface is expanded; the wettability pH response surface is rapidly prepared, the prepared hydrophilic-hydrophobic adjustable cement-based material is hydrophilic in early maintenance stage, and the prepared hydrophilic-hydrophobic adjustable cement-based material is converted into hydrophobicity after being treated by an acidic solution in service stage.

Description

A wettability modifier responsive to pH and a method of using the same

Technical Field

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

Background technique

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

At present, the research on the preparation of wettability stimulus-responsive surfaces is mainly focused on substrates such as sponges, fabrics, metals, and crystals, and there is still a lack of relevant exploration of realizing wettability stimulus-responsive functions on cement-based materials. In the field of cement-based materials, (super) hydrophobic cement-based materials are mainly obtained by adding low surface energy functional components or preparing coatings. However, the existing methods can only obtain cement-based material surfaces 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, and it cannot meet the requirements of anti-fouling and anti-water intrusion in the later service stage.

Summary 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 for wettability responsive to pH that can reduce the adverse effects of hydrophobicity in the early curing stage of cement-based materials, can be quickly prepared, and another purpose of the present invention is to provide two convenient and practical methods for using the modifier for wettability responsive to pH that can meet the requirements of anti-fouling and anti-water intrusion.

Technical solution: The wettability modifier responsive to pH described in the present invention comprises the following substances in parts by weight: 50 to 70 parts of alkyl dicarboxylic acid, 30 to 50 parts of saturated fatty acid, and 1900 to 2000 parts of anhydrous ethanol. The modifier can convert cement-based materials from hydrophilic to hydrophobic.

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

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

The first method of using the above-mentioned wettability modifier that responds to pH, i.e., the impregnation method, comprises the following steps:

Step 1, adding saturated fatty acid and alkyl dicarboxylic acid to anhydrous ethanol according to weight ratio, stirring until completely dissolved, to obtain a modifier;

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

Step 3, taking out the product obtained in step 2, cleaning the surface with deionized water, and then cleaning with anhydrous ethanol, and drying 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 base, wash it with anhydrous ethanol, and dry it to obtain a cement-based material.

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

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

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

The second method of using the above-mentioned wettability modifier that responds to pH, i.e., the internal doping method, comprises the following steps:

Step 1, reacting saturated fatty acid and alkyl dicarboxylic acid with excess hydroxide salt solution according to weight ratio, filtering and drying to obtain saturated fatty acid salt and alkyl dicarboxylic acid salt;

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

Step 3: Mix the additive, water and silicate cement evenly, pour the slurry into a rubber mold for molding, remove the mold, and cure in a natural environment;

Step 4: After curing, the cement sample is rinsed with hydrochloric acid or sulfuric acid solution with a pH value of 4 to 6, and dried at 40 to 50° C. The cement-based material changes from hydrophilic to hydrophobic.

Furthermore, in step three, the water-cement ratio of water to silicate 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 in hydroxyl groups, the carboxylate at one end of saturated fatty acids is used for grafting, and the methyl group at the other end has a lower surface energy to achieve hydrophobic function; the carboxylate at one end of alkyl dicarboxylic acids is used for grafting, and the carboxylate at the other end will be deprotonated at high pH values and become more hydrophilic to achieve the responsiveness to pH values. Saturated fatty acids and alkyl dicarboxylic acids are prepared into corresponding organic acid salts so that they can be dissolved in water to achieve internal addition in cement-based materials. Compared with the physical adsorption effect such as hydrogen bonding formed between the inter-carboxylic acid functional group and the cement-based material by the impregnation method, the modification effect and durability of the internal addition method are better.

Beneficial effects: Compared with the prior art, the present invention has the following significant features:

1. It is convenient for water to enter and cement to hydrate during the early curing process, and no water stains will remain on the horizontal surface of the sample, which can meet the requirements of anti-fouling and anti-water intrusion in the later service stage;

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

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

4. The prepared pH-responsive wettability modifier can be used to quickly prepare a wettability pH-responsive surface on a cement-based material base. The prepared hydrophilic and hydrophobic adjustable cement-based material is hydrophilic in the early curing stage and becomes hydrophobic after being treated with an acidic solution in the service stage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a surface droplet wetting diagram of a modified cement-based material prepared by the impregnation method of the present invention;

FIG2 is a graph showing the change in surface contact angle of a modified cement-based material prepared by the immersion method of the present invention;

3 is a graph showing the surface contact angle of the modified cement-based material prepared by the immersion method of the present invention as a function of the pH value of the solution;

FIG4 is a graph showing the change of the surface contact angle of the modified cement-based material prepared by the internal mixing method of the present invention with the mixing amount;

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

Detailed ways

Example 1

A method for using a modifier whose wettability responds to pH comprises the following steps:

Step 1, 70 parts of saturated fatty acids and 30 parts of alkyl dicarboxylic acids are placed in a container, the alkyl dicarboxylic acid is dodecanedioic acid, and the saturated fatty acid is lauric acid, 1900 parts of anhydrous ethanol are added, that is, the mass percentage of the alkyl dicarboxylic acid in the mixed components (saturated fatty acids, saturated fatty acids) is controlled to be 30%, and the mixed components are stirred until they are completely dissolved in ethanol to obtain a modifier with a mass fraction of 5wt%;

Step 2: Mix water and silicate 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 cure in a natural environment for 7 days;

Step 3, take out the material obtained in step 2, clean the surface with deionized water, and then clean it with anhydrous ethanol, and place the cleaned cement-based material in a drying oven at 50° C. for 6 hours;

Step 4, immersing the product obtained in step 3 in the modifier prepared in step 2, immersing for 6 hours, taking out the treated cement-based material base, washing it with anhydrous ethanol, and drying it in a drying oven at 50° C. for 6 hours to obtain a cement-based material.

Example 2

A method for using a modifier whose wettability responds to pH comprises the following steps:

Step 1, 50 parts of saturated fatty acid and 50 parts of alkyl dicarboxylic acid are placed in a container, the alkyl dicarboxylic acid is dodecanedioic acid, and the saturated fatty acid is lauric acid, 1900 parts of anhydrous ethanol are added, that is, the mass percentage of alkyl dicarboxylic acid in the mixed components (saturated fatty acid, saturated fatty acid) is controlled to be 50%, and stirred until the mixed components are completely dissolved in ethanol to obtain a modifier with a mass fraction of 5wt%;

Step 2: Mix water and silicate 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 cure in a natural environment for 7 days;

Step 3, take out the material obtained in step 2, clean the surface with deionized water, and then clean it with anhydrous ethanol, and place the cleaned cement-based material in a drying oven at 50° C. for 6 hours;

Step 4, immersing the product obtained in step 3 in the modifier prepared in step 2, immersing for 6 hours, taking out the treated cement-based material base, washing it with anhydrous ethanol, and drying it in a drying oven at 50° C. for 6 hours to obtain a cement-based material.

Example 3

A method for using a modifier whose wettability responds to pH comprises the following steps:

Step 1, 30 parts of saturated fatty acids and 70 parts of alkyl dicarboxylic acids are placed in a container, the alkyl dicarboxylic acid is dodecanedioic acid, and the saturated fatty acid is lauric acid, 1900 parts of anhydrous ethanol are added, that is, the mass percentage of the alkyl dicarboxylic acid in the mixed components (saturated fatty acids, saturated fatty acids) is controlled to be 70%, and the mixed components are stirred until they are completely dissolved in ethanol to obtain a modifier with a mass fraction of 5wt%;

Step 2: Mix water and silicate 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 cure in a natural environment for 7 days;

Step 3, take out the material obtained in step 2, clean the surface with deionized water, and then clean it with anhydrous ethanol, and place the cleaned cement-based material in a drying oven at 50° C. for 6 hours;

Step 4, immersing the product obtained in step 3 in the modifier prepared in step 2, immersing for 6 hours, taking out the treated cement-based material base, washing it with anhydrous ethanol, and drying it in a drying oven at 50° C. for 6 hours to obtain a cement-based material.

Sodium hydroxide was used to prepare alkaline liquids of pH = 7 and pH = 13. The two liquids were sucked with a dropper and dropped onto the surface of the cement-based material treated with the modifier. The wetting of droplets of different pH values on the surface is shown in Figure 1. The surface of the modified cement-based material substrate showed good hydrophobic characteristics for pH = 7 droplets, and there was a "silver mirror phenomenon"; while it showed hydrophilic characteristics for pH = 13 droplets, and the droplets quickly wetted and spread on the surface.

Comparative Example 1

The remaining steps of this comparative example are the same as those of Example 1, with the only difference being that in step 1, 100 parts of saturated fatty acids and 0 parts of alkyl dicarboxylic acids are used, i.e., the mass percentage of alkyl dicarboxylic acids in the mixed components (saturated fatty acids, saturated fatty acids) is controlled to be 0%.

Comparative Example 2

The remaining steps of this comparative example are the same as those of Example 1, with the only difference being that in step 1, 0 parts of saturated fatty acid and 100 parts of alkyl dicarboxylic acid, i.e., the mass percentage of alkyl dicarboxylic acid in the mixed components (saturated fatty acid, saturated fatty acid) is controlled to be 100%.

Sodium hydroxide was used to prepare an alkaline liquid with a pH of 13, and deionized water was used as a neutral liquid with a pH of 7. The contact angles of the cement-based material surface modified by the modifiers with different mixed component ratios obtained in Examples 1 to 3 and Comparative Examples 1 to 2 were 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 2. When the proportion of alkyl dicarboxylic acid was 0% and 30%, the contact angles of the cement-based material substrate to the pH = 7 and pH = 13 droplets were not significantly different, and both were maintained at 130° to 140°, showing hydrophobic characteristics. When the proportion of alkyl dicarboxylic acid was 50% and 70%, the contact angles of the cement-based material substrate surface to the pH = 7 and pH = 13 droplets showed obvious differences. The contact angle to the pH = 7 droplet was 115° to 135°, showing hydrophobic characteristics, while the contact angle to the pH = 13 droplet was 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 pH = 7 and pH = 13 droplets, both of which remain at around 20°. When the proportion of alkyl dicarboxylic acid is 70%, the difference in the contact angle of the two droplets is the largest, at 101°. When the pH of the solution is less than 7, the contact angle is the same as when pH = 7.

Example 4

A method for using a modifier whose wettability responds to pH comprises the following steps:

Step 1, 40 parts of saturated fatty acid and 60 parts of alkyl dicarboxylic acid are placed in a container, the alkyl dicarboxylic acid is suberic acid, and the saturated fatty acid is capric acid, 2000 parts of anhydrous ethanol are added, that is, the mass percentage of the alkyl dicarboxylic acid in the mixed component is controlled to be 60%, and stirred until the mixed component is completely dissolved in ethanol to obtain a modifier with a mass fraction of 4.8wt%;

Step 2: Mix water and silicate cement at a water-cement ratio of 0.3, pour the slurry into a rubber mold, remove the mold after 1 day, and cure in a natural environment for 8 days;

Step 3, take out the material obtained in step 2, clean the surface with deionized water, and then clean it with anhydrous ethanol, and place the cleaned cement-based material in a drying oven at 45° C. for 8 hours;

Step 4, immersing the product obtained in step 3 in the modifier prepared in step 2, immersing for 8 hours, taking out the treated cement-based material base, washing it with anhydrous ethanol, and drying it in a drying oven at 45° C. for 7 hours to obtain a cement-based material.

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

Example 5

A method for using a modifier whose wettability responds to pH comprises the following steps:

Step 1, 60 parts of saturated fatty acid and 40 parts of alkyl dicarboxylic acid are placed in a container, the alkyl dicarboxylic acid is tridecanedioic acid, and the saturated fatty acid is stearic acid, 2000 parts of anhydrous ethanol are added, that is, the mass percentage of the alkyl dicarboxylic acid in the mixed component is controlled to be 40%, and stirred until the mixed component is completely dissolved in ethanol to obtain a modifier with a mass fraction of 5wt%;

Step 2: Mix water and silicate cement at a water-cement ratio of 0.3, pour the slurry into a rubber mold, remove the mold after 1 day, and cure in a natural environment for 8 days;

Step 3, take out the material obtained in step 2, clean the surface with deionized water, and then clean it with anhydrous ethanol, and place the cleaned cement-based material in a drying oven at 45° C. for 8 hours;

Step 4, immersing the product obtained in step 3 in the modifier prepared in step 2, immersing for 8 hours, taking out the treated cement-based material base, washing it with anhydrous ethanol, and placing it in a drying oven at 55° C. for 5 hours to obtain a cement-based material.

Example 6

Cement paste samples were prepared and immersed in accordance with the method of Example 1 to obtain cement-based materials with a wettability pH intelligent response function on the surface. Alkaline liquids with pH values of 8, 9, 10, 11, 12, and 13 were prepared using sodium hydroxide, deionized water was used as a neutral liquid with pH value of 7, and hydrochloric acid was used to prepare acidic liquids with pH values of 3 and 5. The contact angles of the cement-based material surface treated with the modifier to droplets of different pH values were tested according to the method of Example 1.

The measurement results are shown in Figure 3. The surface wettability of the cement-based material substrate with a 70% alkyl dicarboxylic acid group is responsive to the pH value. When the pH value of the droplet is less than or equal to 7, the contact angle is above 135°, and the surface is hydrophobic. When the pH value of the droplet is greater than 7, the surface contact angle gradually decreases. When the pH is 12, the contact angle is 22°, and the surface is hydrophilic. The 0% alkyl dicarboxylic acid group always maintains a contact angle of more than 130°, and the 100% alkyl dicarboxylic acid group maintains a contact angle of less than 25°.

Example 7

A method for using a modifier whose wettability responds to pH comprises the following steps:

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

Step 2, weighing saturated fatty acid salt and alkyl dicarboxylate in proportion and placing them in a container, controlling the mass percentage of alkyl dicarboxylate in the mixed components to be 50%, then adding 35° C. water, stirring until completely dissolved, to obtain an additive;

Step 3: Mix the additive, water and silicate cement evenly with a water-cement ratio of 0.3, pour the slurry into a rubber mold for molding, remove the mold after 1 day, and cure in a natural environment for 7 days;

Step 4: After curing, the cement sample is rinsed with HCl solution with a pH value of 4 and dried at 40°C, and the cement-based material changes from hydrophilic to hydrophobic.

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

Example 8

A method for using a modifier whose wettability responds to pH comprises the following steps:

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

Step 2, weighing saturated fatty acid salt and alkyl dicarboxylate in proportion and placing them in a container, controlling the mass percentage of alkyl dicarboxylate in the mixed components to be 70%, then adding 45° C. water and stirring until completely dissolved to obtain an additive;

Step 3: Mix the additive, water and silicate cement evenly with a water-cement ratio of 0.4, pour the slurry into a rubber mold for molding, remove the mold after 1 day, and cure in a natural environment for 8 days;

Step 4: After curing, the cement sample is rinsed with a sulfuric acid solution with a pH value of 5 and dried at 45°C. The cement-based material changes from hydrophilic to hydrophobic.

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

Example 9

A method for using a modifier whose wettability responds to pH comprises the following steps:

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

Step 2, weighing saturated fatty acid salt and alkyl dicarboxylate in proportion and placing them in a container, controlling the mass percentage of alkyl dicarboxylate in the mixed components to be 60%, then adding 40° C. water, stirring until completely dissolved, to obtain an additive;

Step 3: Mix the additive, water and silicate cement evenly with a water-cement ratio of 0.3, pour the slurry into a rubber mold for molding, remove the mold after 1 day, and cure in a natural environment for 7 days;

Step 4: After curing, the cement sample is rinsed with a hydrochloric acid solution with a pH value of 6 and dried at 45°C. The cement-based material changes from hydrophilic to hydrophobic.

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

Example 10

A method for using a modifier whose wettability responds to pH comprises the following steps:

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

Step 2, weighing saturated fatty acid salt and alkyl dicarboxylate in proportion and placing them in a container, controlling the mass percentage of alkyl dicarboxylate in the mixed components to be 0%, 70%, and 100%, then adding 40° C. water and stirring until completely dissolved to obtain an additive;

Step 3: Mix the additives, water and silicate cement evenly, with a water-cement ratio of 0.4, and the mixed components accounting for 0%, 0.5%, 1.0%, 1.5% and 2.0% of the cementitious material. Pour the slurry into a rubber mold for molding, remove the mold after 1 day, and cure in a natural environment for 7 days;

Step 4: After curing, the cement sample is rinsed with a hydrochloric acid solution with a pH value of 6 and dried at 45°C. The cement-based material changes from hydrophilic to hydrophobic.

The contact angle of the cement-based material surface obtained in step 3 with different mixing ratios of water was tested by a video screen optical contact angle meter. The test drop size was 5μL, and three sites were tested on each surface. The measurement results are shown in Figure 4. It can be seen that when the proportion of alkyl dicarboxylates in the mixed components is 0%, the contact angle increases with the increase of the dosage, and finally reaches more than 120°; when the proportion of alkyl dicarboxylates in the mixed components is 70%, the contact angle shows a trend of rising gently and then falling slightly, and remains below 50°, showing hydrophilicity; when the proportion of alkyl dicarboxylates in the mixed components is 100%, the contact angle rises slightly and then falls rapidly. At higher dosages, the contact angle cannot be measured due to strong hydrophilicity.

Embodiment 11

A method for using a modifier whose wettability responds to pH comprises the following steps:

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

Step 2, weighing saturated fatty acid salt and alkyl dicarboxylate in proportion and placing them in a container, controlling the mass percentage of alkyl dicarboxylate in the mixed components to be 70%, then adding 40° C. water and stirring until completely dissolved to obtain an additive;

Step 3: Mix the additives, water and silicate cement evenly, with a water-cement ratio of 0.4, and the mixed components accounting for 0%, 0.5%, 1.0%, 1.5% and 2.0% of the cementitious material. Pour the slurry into a rubber mold for molding, remove the mold after 1 day, and cure in a natural environment for 7 days;

Step 4: After curing, the cement sample is rinsed with a hydrochloric acid solution with a pH value of 5 and dried at 40°C. The cement-based material changes from hydrophilic to hydrophobic.

The contact angle of water on the cement-based material surface before and after treatment was tested using a video optical contact angle meter. 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 dicarboxylates in the mixed components was 70%, the cement-based material was hydrophilic before treatment, and the contact angle remained below 40°; the contact angle of the cement-based material increased after treatment, and when the mixed components accounted for 2.0% of the cementitious material, the contact angle changed from 30° to 120°.

Claims (9)

1. A method of using a wettability-responsive pH modifying agent, comprising the steps of:

adding saturated fatty acid and alkyl dicarboxylic acid into absolute ethyl alcohol according to the weight portion ratio, and stirring until the saturated fatty acid and the alkyl dicarboxylic acid are completely dissolved to obtain a modifier with the mass fraction of 5 wt%;

Step two, mixing water and silicate cement, stirring uniformly, pouring the slurry into a rubber mold for molding, removing the mold, and curing 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;

Immersing the substance obtained in the third step into the modifier prepared in the first step, taking out the treated cement-based material substrate, washing with absolute ethyl alcohol, and drying to obtain a cement-based material;

The wettability-to-pH response modifier comprises the following components in parts by weight: 30-70 parts of alkyl dicarboxylic acid, 30-70 parts of saturated fatty acid and 1900 parts of absolute ethyl alcohol, wherein the modifier can convert the cement-based material from hydrophilicity to hydrophobicity;

The alkyl dicarboxylic acid is dodecanedioic acid;

the saturated fatty acid is lauric acid;

The cement-based material is hydrophilic in the early curing stage and is converted into hydrophobicity after being treated by an acidic solution in the service stage.

2. The method of using a wettability-responsive pH modifying agent of claim 1, wherein: the mass percentage of the alkyl dicarboxylic acid in the saturated fatty acid and alkyl dicarboxylic acid mixed component is 50% or 70%.

3. The method of using a wettability-responsive pH modifying agent of claim 1, wherein: in the second step, the water cement ratio of water to silicate cement is 0.3-0.4, and the curing time is 7-8 days.

4. The method of using a wettability-responsive pH modifying agent of claim 1, wherein: in the third step, the drying temperature is 45-50 ℃ and the drying time is 6-8 hours.

5. The method of using a wettability-responsive pH modifying agent of claim 1, wherein: in the fourth step, the immersing time is 6-8 hours, the drying temperature is 45-55 ℃, and the drying time is 5-7 hours.

6. The method of using a wettability-responsive pH modifying agent of claim 1, wherein: in the fourth step, the drying temperature is 45-55 ℃, and the drying time is 5-7 hours.

7. A method of using a wettability-responsive pH modifying agent, comprising the steps of:

Step one, according to the weight portion ratio, saturated fatty acid and alkyl dicarboxylic acid react with excessive hydrogen oxide salt solution, and saturated fatty acid salt and alkyl dicarboxylic acid salt are obtained after filtration and drying;

Controlling the mass percentage of the alkyl dicarboxylic acid salt in the mixed components to be 50% -70%, then adding 35-45 ℃ water, and stirring until the alkyl dicarboxylic acid salt is completely dissolved to obtain an additive;

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

Washing the cement sample with hydrochloric acid or sulfuric acid solution with the pH value of 4-6 after curing, and drying at 40-50 ℃, wherein the cement-based material is changed from hydrophilic to hydrophobic;

The wettability-to-pH response modifier comprises the following components in parts by weight: 30-70 parts of alkyl dicarboxylic acid, 30-70 parts of saturated fatty acid and 1900 parts of absolute ethyl alcohol, wherein the modifier can convert the cement-based material from hydrophilicity to hydrophobicity;

The alkyl dicarboxylic acid is any one of suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid and tridecanedioic acid;

The saturated fatty acid is any one of capric acid, lauric acid, myristic acid, palmitic acid, pearlitic acid and stearic acid;

The cement-based material is hydrophilic in the early curing stage and is converted into hydrophobicity after being treated by an acidic solution in the service stage.

8. The method of using a wettability-responsive pH modifying agent of claim 7, wherein: in the third step, the water cement ratio of water to silicate cement is 0.3-0.4, and the curing time is 7-8 days.

9. The method of using a wettability-responsive pH modifying agent of claim 7, wherein: the mass percentage of the alkyl dicarboxylic acid salt in the saturated fatty acid and alkyl dicarboxylic acid mixed component is 70%.