Rebar corrosion immediate response rust inhibition system as well as preparation method and application thereof

Abstract

The invention provides a steel bar corrosion immediate response corrosion inhibition system and a preparation method and application thereof, and belongs to the technical field of corrosion inhibitors. The preparation method disclosed by the invention comprises the following steps: mixing triethanolamine, polyphenols and 4-dimethyl pyridine, and then carrying out a reaction, so as to obtain anti-rust molecules; the preparation method comprises the following steps: mixing aniline, ethylbenzene, a lauryl sodium sulfate aqueous solution and rust-inhibiting molecules, and emulsifying to obtain a microemulsion; and mixing the microemulsion with a polyvinyl alcohol aqueous solution, and dropwise adding an ammonium persulfate aqueous solution to carry out polymerization reaction, thereby obtaining the steel bar corrosion immediate response corrosion inhibition system. The corrosion inhibition molecule (at) PANI corrosion inhibition system can immediately respond to steel bar corrosion, the steel bar corrosion rate can be remarkably controlled within 3 h after active corrosion of steel bars occurs, a stable protection layer is formed within 12 h, and generation of steel bar corrosion products is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rust inhibitor, in particular to a steel bar corrosion instant response rust inhibition system and a preparation method and application thereof. BACKGROUND

[0002] Steel bar corrosion induced by chloride salt is one of the main reasons for the deterioration and failure of concrete structures. At present, rust inhibitor is the most commonly used steel bar corrosion prevention technology, which has the advantages of simple application and economic suitability. Conventional rust inhibitors usually have problems of easy loss, degradation failure, and side effects on concrete substrates. Loading rust inhibitor molecules with carrier materials can effectively reduce the loss of rust inhibitor, maintain the long-term rust inhibition activity of rust inhibitor molecules, effectively avoid the phenomenon of side effects caused by direct contact of rust inhibitor molecules with concrete substrates, and realize intelligent response release and improve the effective utilization rate of rust inhibitor. The existing intelligent carrier rust inhibition system includes stress response, ion response, and pH response release modes. However, the above rust inhibition systems face the problems of premature release or untimely response, which cannot guarantee the precise release and protection of rust inhibitor molecules, and the utilization efficiency of rust inhibitor components is low, and rust inhibitor molecules cannot play a rust inhibition role on corroded steel bars.

[0003] Therefore, it is of great practical engineering significance to develop a new type of target rust inhibition system with precise identification and repair. SUMMARY

[0004] The present application relates to the technical field of rust inhibitor, in particular to a steel bar corrosion instant response rust inhibition system and a preparation method and application thereof.

[0005] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0006] The present application provides a preparation method of a steel bar corrosion instant response rust inhibition system, comprising the following steps:

[0007] 1) mixing triethanolamine, a phenolic compound, and 4-dimethylpyridine, and then reacting to obtain a rust inhibitor molecule;

[0008] 2) mixing aniline, ethylbenzene, a sodium dodecyl sulfate aqueous solution, and the rust inhibitor molecule, and then emulsifying to obtain a microemulsion;

[0009] 3) mixing the microemulsion and a polyvinyl alcohol aqueous solution, and then adding an ammonium persulfate aqueous solution dropwise to perform a polymerization reaction to obtain a steel bar corrosion instant response rust inhibition system.

[0010] Preferably, the mass ratio of the triethanolamine, the phenolic compound, and the 4-dimethylpyridine in step 1) is 15-30: 18-32: 0.2-0.8.

[0011] Preferably, the temperature of the reaction in step 1) is 105-135℃, and the reaction time is 10-15h.

[0012] Preferably, the volume ratio of the aniline, ethylbenzene and aqueous sodium dodecyl sulfate solution in step 2) is 4-6:10-13:50; the volume-mass ratio of the aniline and the rust-preventing molecule is 4-6 mL:0.2-0.4 g, and the concentration of the aqueous sodium dodecyl sulfate solution is 1.05-1.45 g / 100 mL.

[0013] Preferably, the mixing process in step 2) is as follows: the aniline, ethylbenzene and aqueous sodium dodecyl sulfate solution are first mixed, and then the first mixture is secondly mixed with the rust-preventing molecule; the rotation speed of the first mixing is 800-1200 rpm, and the time is 0.5-1.5 h.

[0014] Preferably, the emulsification in step 2) is ultrasonic emulsification, and the power of the ultrasonic emulsification is 385-425 W, and the time is 250-350 s.

[0015] Preferably, the mass fraction of the aqueous polyvinyl alcohol solution in step 3) is 7-13%, the volume ratio of the aqueous polyvinyl alcohol solution and the aniline is 4-6:1, and the molar ratio of the ammonium persulfate and the aniline is 0.7-1.3:0.7-1.3; the rotation speed of the polymerization reaction is 800-1200 rpm, and the time is 10-14 h.

[0016] The application further provides the steel bar corrosion instant response rust-preventing system prepared by the preparation method.

[0017] The application further provides application of the steel bar corrosion instant response rust-preventing system in inhibiting steel bar corrosion.

[0018] The application has the following beneficial effects:

[0019] (1) The application successfully prepares PANI microcapsules with a diameter of 400-1000 nm, and successfully loads rust-preventing molecules to form a rust-preventing molecule@PANI microcapsule rust-preventing system. The rust-preventing system of the application has relatively sensitive responsiveness to reduction reactions, and can quickly release the encapsulated rust-preventing agent after response, thus showing a wide application prospect in the field of steel bar corrosion control.

[0020] (2) The rust-preventing molecule@PANI rust-preventing system of the application can instantaneously respond to steel bar corrosion, can significantly control the steel bar corrosion rate within 3 h after the steel bar is actively corroded, and can form a stable protective layer within 12 h to reduce the generation of steel bar corrosion products.

[0021] (3) When the steel bar is active corrosion, the shell of the rust-preventing molecule PANI rust-preventing system is broken, the rust-preventing molecule is released, the rust-preventing molecule is combined with Fe ions at the active site and Ca ions in the solution to form a hardly soluble coordination compound, and is adsorbed on the surface of the steel bar by O and N heteroatom groups to form a dense organic protective layer with the PANI shell, so that the corrosion of the steel bar is effectively controlled. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 SEM image of polyaniline microcapsules of Comparative Example 1;

[0023] Figure 2 UV-visible spectrum of PANI of Comparative Example 1, TG of Example 1 and TG@PANI;

[0024] Figure 3 FTIR spectrum of PANI of Comparative Example 1, TG of Example 1 and TG@PANI;

[0025] Figure 4 SEM images of PANI of Comparative Example 1 and TG@PANI of Example 1 before and after being immersed in 0.05mmol / L DTT solution, wherein a and c are before immersion, and b and d are after immersion;

[0026] Figure 5 TG concentration-time change image of TG@PANI of Example 1 immersed in pure water, DTT solution and H2O2 solution;

[0027] Figure 6 Open circuit potential-time change image of carbon steel immersed in different simulated solutions within 72h;

[0028] Figure 7 SEM images and corresponding EDS spectrum images of the surface of the carbon steel sample immersed in SP0, SP1 and SPTG1 solutions for 72h, wherein a is the blank group, b is 0.1% PANI added, and c is 0.1% TG@PANI added;

[0029] Figure 8 Raman spectrum of the surface of the carbon steel sample immersed in SP0, SP1 and SPTG1 solutions for 72h;

[0030] Figure 9 XPS scanning spectrum of the surface of the carbon steel immersed in SP0, SP1 and SPTG1 for 24h. DETAILED DESCRIPTION

[0031] The application provides a preparation method of a steel bar corrosion instant response rust-preventing system, and comprises the following steps:

[0032] 1) mixing triethanolamine, phenolic compound and 4-dimethylpyridine and then performing reaction to obtain rust-preventing molecules;

[0033] 2) mixing aniline, ethylbenzene, aqueous solution of sodium dodecyl sulfate and rust-preventing molecules and then performing emulsification to obtain microemulsion;

[0034] 3) mixing microemulsion and aqueous solution of polyvinyl alcohol, then adding aqueous solution of ammonium persulfate dropwise to perform polymerization reaction to obtain instant response rust-preventing system for steel bar corrosion.

[0035] In the present application, the phenolic compound is preferably gallic acid, protocatechuic acid, coffee acid, salicylic acid or ellagic acid.

[0036] In the present application, the mass ratio of triethanolamine, phenolic compound and 4-dimethylpyridine in step 1) is preferably 15-30:18-32:0.2-0.8, further preferably 20-24:23-27:0.5-0.7, and more preferably 22:25:0.6.

[0037] In the present application, the temperature of the reaction in step 1) is preferably 105-135 DEG C, further preferably 115-125 DEG C, and more preferably 120 DEG C, and the reaction time is preferably 10-15 h, further preferably 11-14 h, and more preferably 12-13 h.

[0038] In the present application, the temperature of the mixing in step 1) is preferably 95-105 DEG C, and further preferably 100 DEG C, and the mixing is performed until the phenolic compound is completely dissolved; and after the reaction in step 1) is completed, the mixture is cooled to room temperature to obtain rust-preventing molecules.

[0039] In the present application, the route for synthesizing gallic acid ester rust-preventing molecules from triethanolamine, phenolic compound (gallic acid) and catalyst 4-dimethylpyridine is as shown below:

[0040]

[0041] In the present application, the volume ratio of aniline, ethylbenzene and aqueous solution of sodium dodecyl sulfate in step 2) is preferably 4-6:10-13:50, further preferably 4.5-5.5:10.8-12.2:50, and more preferably 4.9-5.0:11.4-11.5:50; the volume-mass ratio of aniline and rust-preventing molecules is preferably 4-6 mL:0.2-0.4 g, further preferably 4.5-5.5 mL:0.28-0.32 g, and more preferably 4.9-5.0 mL:0.3 g; and the concentration of the aqueous solution of sodium dodecyl sulfate is preferably 1.05-1.45 g / 100 mL, further preferably 1.15-1.35 g / 100 mL, and more preferably 1.25 g / 100 mL.

[0042] In the present application, the mixing process of step 2) is preferably as follows: first mixing of aniline, ethylbenzene and aqueous sodium dodecyl sulfate solution, and then second mixing of the first mixture with the rust-preventing molecule; the rotation speed of the first mixing is preferably 800-1200 rpm, further preferably 900-1100 rpm, and more preferably 1000 rpm; and the time of the first mixing is preferably 0.5-1.5 h, further preferably 0.6-1.2 h, and more preferably 1 h.

[0043] In the present application, the emulsification of step 2) is preferably ultrasonic emulsification, and the power of the ultrasonic emulsification is preferably 385-425 W, further preferably 395-415 W, and more preferably 405 W; and the time of the ultrasonic emulsification is preferably 250-350 s, further preferably 280-320 s, and more preferably 300 s.

[0044] In the present application, the mass fraction of the polyvinyl alcohol aqueous solution of step 3) is preferably 7-13%, further preferably 9-11%, and more preferably 10%; the volume ratio of the polyvinyl alcohol aqueous solution to aniline is preferably 4-6:1, further preferably 4.5-5.5:1, and more preferably 5:1; the molar ratio of ammonium persulfate to aniline is preferably 0.7-1.3:0.7-1.3, further preferably 0.9-1.1:0.9-1.1, and more preferably 1:1; the rotation speed of the polymerization reaction is preferably 800-1200 rpm, further preferably 900-1100 rpm, and more preferably 1000 rpm; and the time of the polymerization reaction is preferably 10-14 h, further preferably 11-13 h, and more preferably 12 h.

[0045] In the present application, the route for synthesizing PANI microcapsules from aniline and ammonium persulfate is as follows:

[0046]

[0047] The present application also provides a steel bar corrosion instant response rust-preventing system prepared by the preparation method.

[0048] The present application also provides the use of the steel bar corrosion instant response rust-preventing system in inhibiting steel bar corrosion.

[0049] The technical solutions provided by the present application will be described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the present application.

[0050] In the examples and comparative examples, the weight average molecular weight of polyvinyl alcohol (PVA) is 35,000, the hydrolysis degree is 98.5%, the mass fraction of the hydrogen peroxide aqueous solution is 3%, and the purity of triethanolamine (TE) is 99%.

[0051] The ultraviolet-visible spectrophotometer (UV-vis) was a platinum gold Lambda 750; the Fourier transform infrared spectra (FTIR) were recorded on a Thermo Fisher Scientific Nicolet iS20 spectrometer in the frequency range 400-4000 cm -1 at a resolution of 1 cm -1 -1; the scanning electron microscope was a Zeiss Sigma 300 scanning electron microscope.

[0052] Example 1

[0053] At room temperature, 22 g of triethanolamine was placed in a three-necked flask equipped with a condenser, a thermometer and a mechanical stirrer, then the flask was immersed in a magnetically stirred oil bath, heated to 100°C to reduce the viscosity of the triethanolamine; after heating for 30 min, 25 g of gallic acid was slowly added to the flask, followed by the addition of 0.6 g of 4-dimethylpyridine as a catalyst, mixed until the gallic acid was completely dissolved, the temperature of the oil bath was increased to 120°C, and the mixture was continuously stirred at a speed of 600 rpm for 12 h; after cooling the mixture in the three-necked flask to room temperature, a reddish-brown liquid, i.e. gallic acid ester TG, was obtained.

[0054] A mixture of 4.9 mL of aniline and 11.4 mL of ethylbenzene was added to 50 mL of water containing 0.625 g of sodium dodecyl sulfate, stirred at room temperature at a speed of 1000 rpm for 1 h, then 0.3 g of gallic acid ester TG was added, mixed uniformly, and emulsified with ultrasonic power of 405 W for 300 s. After emulsification, 24.5 mL of polyvinyl alcohol aqueous solution (10 wt.%) was mixed with the microemulsion, and an aqueous solution of ammonium persulfate (molar ratio of aniline to ammonium persulfate was 1:1) was added dropwise into the mixture at a rate of 4 mL / min at room temperature. As the polymerization proceeded, the color of the microemulsion changed from white to brown, and then to dark green. After stirring at room temperature at a speed of 1000 rpm for 12 h, the polyaniline was filtered, washed repeatedly with deionized water several times to remove excess reactants until the filtrate was clear. Finally, it was dried in a vacuum oven at 80°C for 8 h to obtain a rust-resistant system (TG@PANI).

[0055] Comparative Example 1

[0056] Example 1 was omitted, and 0.3 g of gallic acid ester TG was obtained, to obtain polyaniline microcapsules (PANI).

[0057] Example 2

[0058] The preparation process of gallic acid ester TG was the same as in Example 1.

[0059] A mixture of 4.5 mL of aniline and 10.8 mL of ethylbenzene was added to 50 mL of water containing 0.575 g of sodium dodecyl sulfate, and after stirring at room temperature at a speed of 900 rpm for 1.2 h, 0.25 g of gallate TG was added, and after uniform mixing, emulsification was performed by ultrasonic treatment at a power of 395 W for 320 s. After emulsification, 27 mL of a polyvinyl alcohol aqueous solution (9 wt.%) was mixed with the microemulsion, and an aqueous solution of ammonium persulfate (molar ratio of aniline to ammonium persulfate: 1:1) was added dropwise to the mixture at a rate of 4 mL / min at room temperature. As the polymerization proceeded, the color of the microemulsion changed from white to brown and then to dark green. After stirring at room temperature at a speed of 900 rpm for 13 h, the polyaniline was filtered, and washed repeatedly with deionized water several times to remove excess reactants until the filtrate was clear. Finally, drying was performed in a vacuum oven at 80°C for 8 h to obtain a rust-preventing system (TG@PANI).

[0060] Example 3

[0061] The gallate TG was prepared in the same manner as in Example 1.

[0062] A mixture of 5.5 mL of aniline and 12.2 mL of ethylbenzene was added to 50 mL of water containing 0.675 g of sodium dodecyl sulfate, and after stirring at room temperature at a speed of 1100 rpm for 1 h, 0.35 g of gallate TG was added, and after uniform mixing, emulsification was performed by ultrasonic treatment at a power of 415 W for 280 s in an ice-cooled environment. After emulsification, 24.75 mL of a polyvinyl alcohol aqueous solution (11 wt.%) was mixed with the microemulsion, and an aqueous solution of ammonium persulfate (molar ratio of aniline to ammonium persulfate: 1:1) was added dropwise to the mixture at a rate of 4 mL / min at room temperature. As the polymerization proceeded, the color of the microemulsion changed from white to brown and then to dark green. After stirring at room temperature at a speed of 1100 rpm for 11 h, the polyaniline was filtered, and washed repeatedly with deionized water several times to remove excess reactants until the filtrate was clear. Finally, drying was performed in a vacuum oven at 80°C for 8 h to obtain a rust-preventing system (TG@PANI).

[0063] Example 4

[0064] The gallate of Example 1 was replaced with protocatechuic acid, and the other process conditions were the same as in Example 1.

[0065] Example 5

[0066] The gallate TG of Example 1 was replaced with caffeic acid, and the other process conditions were the same as in Example 1.

[0067] Performance tests were performed on the gallate TG of Example 1, the rust-preventing system TG@PANI, and the polyaniline microcapsule PANI of Comparative Example 1.

[0068] (1) Characterization of redox-responsive carriers

[0069] The performance of the polyaniline microcapsules was characterized by microscopic testing method. The SEM image of the polyaniline microcapsules of Comparative Example 1 is shown in Figure 1 . The polyaniline microcapsules are uniform spherical particles in appearance and independent of each other. The size of the microcapsules varies, but the size difference is small, and most of the microcapsules have a diameter of 400-1000 nm from the image.

[0070] The UV-Vis spectra of PANI of Comparative Example 1 and TG of Example 1 are shown in Figure 2 . The FTIR spectra of PANI of Comparative Example 1, TG and TG@PANI of Example 1 are shown in Figure 3 . It can be seen from Figure 2 that the polyaniline microcapsules and TG have strong peaks at wavelengths of 310 nm and 277 nm, respectively, which are attributed to the π-π* absorption band related to benzene structure. The absorption peak at a wavelength of 277 nm is the largest, which can be used as the characteristic peak of TG to determine the concentration in the solution. It can be seen from Figure 3 that in the spectrum of the polyaniline microcapsules, peaks at 1569 cm -1 and 1493 cm -1 can be observed, which are derived from the stretching vibration of C=C bond in benzene ring and quinone ring. The peaks near 1295 cm -1 and 1139 cm -1 are related to the stretching vibration of C-N bond. The peaks at 725-890 cm -1 are derived from the in-plane bending vibration peak of benzene ring. The FTIR spectrum of TG@PANI changes significantly, and the peaks near 3300 cm -1 and 2948 cm -1 are attributed to the stretching vibration of -OH bond of hydroxyl group and -C-H bond of saturated hydrocarbon in TG. The peaks at 1081 cm -1 and 1036 cm -1 increase, which are related to the stretching vibration of C-O bond in TG, indicating that TG is successfully loaded in the polyaniline microcapsules.

[0071] (2) Release of redox-responsive carrier

[0072] The SEM images of PANI of Comparative Example 1 and TG@PANI of Example 1 before and after being soaked in 0.05 mmol / L DTT solution are shown in Figure 4 , wherein a and c are before soaking, and b and d are after soaking; the TG concentration-time change image of TG@PANI of Example 1 soaked in pure water, 0.05 mmol / L DTT solution and 0.05 mmol / L H2O2 solution (the concentration of TG@PANI in the solution is 0.50 g / L) is shown in Figure 5 . It can be seen fromFigure 4 It can be seen that before adding the reducing agent, the microcapsules are complete spherical as a whole, and after reduction by the DTT-containing solution, the microcapsule morphology changes significantly, the capsule wall is broken, and large holes are formed, which can release the contents. This is because the PANI is affected by the reducing agent, and changes from the fully oxidized state to the semi-oxidized or reduced state, which reduces the conjugated structure and leads to structural damage. From the SEM images of the microcapsules before and after reduction, it can be seen that the microcapsules are complete spherical as a whole before adding the reducing agent, and after reduction by the DTT-containing solution, the microcapsule morphology changes significantly, the capsule wall is broken, and large holes are formed, which can release the contents. This is because the PANI is affected by the reducing agent, and changes from the fully oxidized state to the semi-oxidized or reduced state, which reduces the conjugated structure and leads to structural damage. Figure 5 It can be seen that in pure water and H2O2-containing environment, the TG concentration does not change significantly with time, indicating that the microcapsules do not break down in water environment and in the presence of oxidizing agent, and the system has weak response to oxidizing agent. However, when it is immersed in 0.05 mmol / L DTT, the TG concentration increases rapidly within 3 h, and the concentration tends to be stable after 12 h, indicating that the microcapsule system has strong sensitivity to reducing agent. When the microcapsules are stimulated by reduction reaction, the structure is destroyed, and the contents are released rapidly, realizing timely response. The TG concentration in the solution is about 125 g / mL after 24 h, and it can be inferred that the loading efficiency (LE) of the microcapsules is about 25-30%.

[0073] (3) Electrochemical behavior of the carrier acting on the surface of the steel bar

[0074] The carbon steel is a cylindrical Q235 carbon steel with a diameter of 10 mm, the elastic modulus Es is 210 x 105N / mm 2 , and the Poisson's ratio is 0.33. The mass percentage of each element in the carbon steel is: C 0.17%, Si 0.09%, Mn 0.28%, S 0.007%, P 0.011%, and the balance is Fe.

[0075] Preparation of steel bar samples: The carbon steel (HRB400) sample is sealed with epoxy resin sealant (any commercially available epoxy resin sealant can be used, and the sealing thickness is 4 mm), and the exposed working surface has a diameter of 10 mm and an area of 78.5 mm2. External wires are connected to facilitate electrochemical testing. The exposed surface of the steel sample is polished with 80 mesh, 400 mesh, 800 mesh, 1500 mesh, 2000 mesh, 3000 mesh, and 4000 mesh sandpaper, respectively, and then polished to a mirror surface with diamond polishing agent (1.0 μm, 0.5 μm), and then washed with deionized water and anhydrous ethanol. Finally, it is placed in a vacuum drying oven and dried at 60°C for standby.

[0076] The corrosion of the steel bar samples in different environments was tested by electrochemical test method. The electrochemical test of three-electrode cell system was carried out by electrochemical workstation. The working electrode was carbon steel sample, and the saturated calomel electrode (SCE) and platinum electrode were used as reference electrode and counter electrode, respectively. The electrolyte was simulated concrete pore solution, and the steel bar samples were placed in three kinds of simulated solutions respectively, and the OCP value of the sample was continuously monitored. The electrochemical test was carried out for three times to ensure the repeatability of each test.

[0077] SP0 was a saturated Ca(OH)2 solution with 3.5% NaCl added as a blank group for corrosion solution; SP1 was a saturated Ca(OH)2 solution with 3.5% NaCl added and 0.1% PANI from Comparative Example 1 added; SPTG1 was a saturated Ca(OH)2 solution with 3.5% NaCl added and 0.1% TG@PANI from Example 1 added. SP1 and SPTG1 were used as rust inhibitor groups.

[0078] The graphs showing the change in open-circuit potential of carbon steel immersed in different simulated solutions over 72 hours are as follows: Figure 6 As shown, by Figure 6 It was observed that in the initial immersion stage, the open circuit potential of all samples showed a decreasing trend, indicating a strong electrochemical reaction on the surface of the carbon steel samples, which intensified over time. With continued immersion, the open circuit potential of the blank group samples decreased continuously with increasing time, stabilizing after 24 hours, with the OCP below -0.5V, indicating a vigorous electrochemical reaction on the steel surface and a rapid corrosion rate. The carbon steel samples under the influence of PANI and TG@PANI microcapsules showed a rebound in OCP value after 3 hours of immersion, with a more significant rebound in the TG@PANI group, indicating that the addition of microcapsules slowed down the corrosion rate of the steel, and the control effect was significantly enhanced after loading with TG. After 72 hours of immersion, the OCP of the TG-loaded PANI microcapsule group remained at a high level, while the OCP value of the pure PANI microcapsule group showed a decreasing trend. This indicates that single PANI microcapsules have limited inhibitory effect on the corrosion of carbon steel, while TG@PANI microcapsules can significantly control the corrosion of the steel. When steel was initially immersed in the simulated solution, it was exposed to a high concentration of Cl... - The increased surface activity of the reinforcing steel can lead to localized corrosion. While the addition of PANI allows the organic polymer molecules to continuously adsorb onto the steel surface via their polar groups, limiting corrosion to some extent, the effect is limited. Adding TG-loaded PANI microcapsules triggers capsule rupture during active corrosion, releasing the encapsulated TG corrosion inhibitor and further slowing the corrosion rate.

[0079] (4) Surface material and morphology

[0080] SP0 was a saturated Ca(OH)2 solution with 3.5% NaCl added as a blank group for corrosion solution; SP1 was a saturated Ca(OH)2 solution with 3.5% NaCl added and 0.1% PANI from Comparative Example 1 added; SPTG1 was a saturated Ca(OH)2 solution with 3.5% NaCl added and 0.1% TG@PANI from Example 1 added. SP1 and SPTG1 were used as rust inhibitor groups.

[0081] 1) SEM / EDS analysis: To further evaluate the protective effect of the rust- resistant system, the surface of the carbon steel samples immersed in different solutions for 72 h was analyzed for morphology and elements.

[0082] The SEM images of the surface of the carbon steel samples immersed in SP0, SP1 and SPTG1 solutions for 72 h and the corresponding EDS spectra are shown in Figure 7 , where a is the blank group, b is the addition of 0.1% PANI, and c is the addition of 0.1% TG@PANI. As can be seen from Figure 7 (a), there are a large number of uneven protrusions on the surface of the sample, and it is porous. Combined with EDS element analysis, it is found that the porous product is mainly composed of Fe and O elements, and it is speculated that it is the iron oxide generated by the corrosion of the reinforcing bar. It shows that the sample in the blank group has been subjected to the invasion of high concentration Cl - , and obvious pitting has occurred. Figure 7 (b) can be seen that there is no obvious large volume of iron oxide formed on the surface of the carbon steel, but a large number of pores of different sizes can be observed. After magnification, it is found that (Figure b-1) there are many sheet-like and needle-like substances together to form a porous surface, and combined with EDS analysis, it is known that it is mainly iron oxide, which may be Fe2O3 and FeOOH. It shows that although the surface of the sample is more uniform than that of the blank group, obvious corrosion has occurred, and the small pores on the surface are caused by the local corrosion of the reinforcing bar induced by Cl - . The protection of the polyphenylamine microcapsule loaded with TG on the reinforcing bar against Cl - erosion is limited. Figure 7 (c) can be seen that the surface of the sample is uniform and smooth, and the local corrosion pits are obviously reduced. Further observation shows that the surface is uniformly covered with a layer of sheet-like substance, and the element analysis result shows that it is mainly composed of Fe, C and O elements, indicating that a thin layer of organic matter is covered on the surface, and the Fe element is obviously more from the carbon steel substrate. The morphology of the sheet-like substance is obviously different from that of the iron oxide in Figure (b-1), which may be the destroyed polyphenylamine microcapsule shell. It shows that the polyphenylamine microcapsule loaded with TG can release TG after being destroyed, form a dense protective layer on the surface of the reinforcing bar, block the invasion of the corrosion medium, and thus protect the reinforcing bar from serious corrosion.

[0083] 2) Raman spectrum

[0084] The composition of the surface material of the carbon steel sample immersed in the three solutions for 72 h was analyzed by Raman spectrum, and the Raman spectrum of the surface of the carbon steel sample immersed in SP0 (blank group), SP1 (PANI) and SPTG1 (TG@PANI) solution for 72 h is shown in Figure 8 . As can be seen from Figure 8 , the surface of the sample in the blank group is mainly composed of Fe, C and O elements, and the Raman spectrum shows that the main peaks are at 222.1 cm -1 , 209.4 cm -1 and 600.4 cm-1 The peaks observed at 399.8 cm -1 and 1314.1 cm -1 are attributed to γ-FeOOH, and the peaks observed at 536.4 cm -1 and 673.2 cm -1 are attributed to Fe3O4. It is shown that there are a large amount of iron oxides on the surface of the sample, which are also the corrosion products of iron in alkaline environment, indicating that the blank group steel sample has been obviously corroded after 72 h.

[0085] Compared with the blank sample, the iron oxides on the surface of the steel sample of the PANI microcapsule group (SP1) are reduced, and the peaks observed at 547.6 cm -1 and 678.2 cm -1 are attributed to Fe3O4. Moreover, new peaks appear in the region of 1300-1600 cm -1 , which are similar to those of the SPTG1 group and are mainly attributed to the vibration of benzene ring. The results show that the addition of PANI is insufficient to significantly control the progress of steel corrosion, and some corrosion products still appear on the surface. However, when TG@PANI microcapsules (SPTG1) are added, the capsules will be destroyed and release TG when corrosion occurs, and TG will react with metal ions at the active corrosion site to form chelates, which are adsorbed on the surface of the steel bar and form a dense protective layer to block the invasion of corrosive media, effectively controlling the progress of corrosion. It is shown that the TG-loaded PANI microcapsule system can effectively control the progress of steel corrosion and weaken the influence of corrosion on the performance of steel bars.

[0086] 3) X-ray photoelectron spectroscopy (XPS)

[0087] The XPS scanning spectrum of the surface of the carbon steel after immersion in SP0 (blank group), SP1 (PANI added), and SPTG1 (TG@PANI added) for 24 h is shown in Figure 9 It can be seen from Figure 9 that the Fe element peak is observed in all three groups of samples, indicating that the surface of the steel bar is covered with iron oxides. The C element peak of the blank sample is obviously smaller, and there is no N element peak, while the N element peak is obviously observed on the surface of the samples with added PANI and TG@PANI, indicating that PANI and TG@PANI are adsorbed on the surface of the steel bar. TG@PANI has a more obvious N peak, indicating an increase in N-containing organic matter, which is attributed to the N atom group in the TG molecule, indicating that TG is released and adsorbed on the steel surface in large amounts.

[0088] The application constructs a redox response targeted rust prevention system (TG@PANI microcapsule) by loading TG in spherical polyaniline. The rust prevention system of the application is sensitive to oxidation reaction, and can release TG quickly under the action of a reducing agent, and can be used for targeted treatment of active corrosion sites. TG@PANI can effectively control the corrosion of steel bars in a concrete simulation solution, significantly inhibits the corrosion rate within 3 hours after the active corrosion of the steel bar, and forms a stable protective layer after 12 hours. The action mechanism is that when the steel bar corrodes, the oxidation of Fe triggers the destruction of PANI to release TG, and TG forms a coordination compound with the active site Fe ion, and relies on the O and N heteroatom groups to be adsorbed on the surface of the steel bar, and together with PANI, a dense organic protective layer is formed to control the development of corrosion.

[0089] The application provides a novel green organic polyphenol rust prevention molecule having a repairing and protecting effect on corroded steel bars, a carrier material sensitive to the reduction reaction of the corrosion process of the steel bar is prepared, the rust prevention molecule is released in response to the corrosion of the steel bar in real time, and the rust prevention molecule reacts with the corrosion site, breaks through the functional limitation that traditional rust prevention agents are mainly used for prevention, realizes accurate targeted repair and effective control of the corrosion site of the steel bar, and guarantees accurate and efficient use of the rust prevention molecule.

[0090] The above only describes the preferred embodiments of the application, and it should be noted that, for ordinary skilled persons in the art, some improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements should also be regarded as the protection scope of the application.

Claims

1. A method for preparing an instant-response corrosion-inhibiting system for reinforcing steel, characterized in that, It includes the following steps: 1) Triethanolamine, phenolic compounds and 4-dimethylpyridine are mixed and reacted to obtain rust-inhibiting molecules; 2) A mixture of aniline, ethylbenzene, sodium dodecyl sulfate aqueous solution and rust-inhibiting molecules is emulsified to obtain a microemulsion; 3) Mix the microemulsion and polyvinyl alcohol aqueous solution, and then add ammonium persulfate aqueous solution dropwise to carry out the polymerization reaction to obtain the steel reinforcement corrosion immediate response rust inhibitor system.

2. The preparation method according to claim 1, characterized in that, The mass ratio of triethanolamine, phenolic compounds and 4-dimethylpyridine in step 1) is 15-30:18-32:0.2-0.

8.

3. The preparation method according to claim 1 or 2, characterized in that, The reaction temperature in step 1) is 105–135°C, and the reaction time is 10–15 h.

4. The preparation method according to claim 3, characterized in that, In step 2), the volume ratio of aniline, ethylbenzene, and sodium dodecyl sulfate aqueous solution is 4-6:10-13:50; the volume-to-mass ratio of aniline and rust-inhibiting molecules is 4-6 mL:0.2-0.4 g; and the concentration of sodium dodecyl sulfate aqueous solution is 1.05-1.45 g / 100 mL.

5. The preparation method according to claim 4, characterized in that, Step 2) The mixing process is as follows: aniline, ethylbenzene and sodium dodecyl sulfate aqueous solution are mixed for the first time, and the first mixture is then mixed with the rust inhibitor molecules for the second time; the rotation speed of the first mixing is 800-1200 rpm and the time is 0.5-1.5 h.

6. The preparation method according to claim 1 or 4, characterized in that, Step 2) The emulsification is ultrasonic emulsification, with a power of 385-425W and a time of 250-350s.

7. The preparation method according to claim 6, characterized in that, In step 3), the mass fraction of the polyvinyl alcohol aqueous solution is 7-13%, the volume ratio of polyvinyl alcohol aqueous solution to aniline is 4-6:1, and the molar ratio of ammonium persulfate to aniline is 0.7-1.3:0.7-1.3; the polymerization reaction is carried out at a speed of 800-1200 rpm for 10-14 hours.

8. The steel reinforcement corrosion-responsive rust-inhibiting system prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the instant-response corrosion inhibitor system for reinforcing steel as described in claim 8 in suppressing reinforcing steel corrosion.

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