CN115477734B - Preparation method of intrinsic type in-situ self-repairing anti-corrosion polymer - Google Patents

Abstract

The invention discloses a preparation method of an intrinsic type in-situ self-repairing anti-corrosion polymer, which comprises the following steps: 1) Dissolving a diamine chain extender containing catechol functional groups in an ultra-dry solvent, adding triethylamine, centrifuging to obtain supernatant, dropwise adding the supernatant into diisocyanate, and continuing to react after the dropwise addition is finished; 2) Adding an organic solution for dissolving the organic silicon resin, continuing to react after the dripping is finished, or 2) dissolving the organic silicon resin in an ultra-dry solvent, dropwise adding the product obtained in the step 1) under the protection of argon, adding a dibutyltin dilaurate catalyst after the dripping is finished, heating to 70-90 ℃, continuing to react, and controlling the organic silicon resin: chain extender: the molar ratio of diisocyanate is 1: a:1+a, wherein 0 < a.ltoreq.1; after the reaction is finished, precipitating in deionized water, dissolving in an organic solvent, drying to obtain a product, dissolving in the organic solvent, coating on a polished metal substrate, and volatilizing the solvent to obtain the coating. The coating has self-repairing anti-corrosion performance.

Description

A kind of preparation method of intrinsic type in-situ self-healing anticorrosion polymer

technical field

The invention belongs to the technical field of self-repairing polymers, and relates to a preparation method of an intrinsic type in-situ self-repairing anticorrosion polymer.

Background technique

Metal corrosion not only brings huge economic burden, but also may cause serious safety problems and environmental disasters. Protective coatings with anti-corrosion properties are considered to be the most effective, economical, and convenient strategy for metal corrosion protection. However, anti-corrosion coatings are used in various natural environments, and microcracks are easily formed on the surface, resulting in the penetration of water and other corrosive media and loss of protection. Self-healing anti-corrosion coatings can recover by themselves or restore their original anti-corrosion effects under certain conditions after being damaged by external forces or environmental damage. It is an emerging intelligent protective material.

At present, self-healing anti-corrosion coatings are mainly based on external self-healing strategies of microcapsule or microsphere systems. For example, water-triggered double-wall microcapsules (CN202210558742.0) coated with isocyanate substances, polyurea microcapsules (CN111909557B) coated with liquid hydrocarbons, oil-soluble corrosion inhibitors and polyamine compounds, etc., when the coating is broken When the microcapsules are broken, the released film-forming substance undergoes a cross-linking reaction at the damaged part of the coating to restore the physical barrier properties of the coating. Another strategy is to coat the corrosion inhibitor with microspheres or nano-containers, and the corrosion inhibitor precipitated from the damaged coating is adsorbed on the surface of the exposed metal substrate, and the continuation of the corrosion electrochemical reaction is inhibited by physical or chemical action. For example, the quinoline nano-metal-organic framework material nano-container loaded with zinc phosphate (CN112457696B), and the polypyrrole-wrapped graphene corrosion inhibitor container (CN202210336957.8). The self-healing strategy of foreign aid often needs to introduce foreign substances into the anti-corrosion material, which may affect the performance of the coating itself and reduce the anti-corrosion effect, while the intrinsic self-healing polymer often requires external intervention, such as heating (CN113004477B), dripping For acid solution catalysis (CN112940214B), it is urgent to develop intrinsic self-healing and anti-corrosion polymers that do not require additional substances, and can achieve self-healing and anti-corrosion functions without human intervention.

The invention discloses the preparation of an intrinsic polymer capable of realizing self-repair and anticorrosion. Using the cross-linking effect between the chemical substances produced by the electrochemical reaction of the corrosion and the functional groups in the polymer molecular chain, the polymer can spontaneously form a passivation film, realize the in-situ self-repair of the damage, and prevent the corrosive droplets from penetrating into the coating , improve the long-term effectiveness of anti-corrosion coatings, provide an effective strategy for self-healing anti-corrosion in harsh corrosive environments that are difficult to operate manually, and have broad application prospects.

Contents of the invention

In view of this, the present invention provides a preparation method of an intrinsic in-situ self-healing anticorrosion polymer.

The present invention specifically provides the following technical solutions:

A preparation method of an intrinsic type in-situ self-repairing anticorrosion polymer, the steps are as follows:

1) removing moisture from the silicone resin, which is bis(3-aminopropyl)-terminated polydimethylsiloxane or bis(hydroxyalkyl)-terminated polydimethylsiloxane;

The chemical structure of bis(3-aminopropyl)-terminated polydimethylsiloxane is:

Wherein, the number of repeating units n is 10-300;

The chemical structure of bis(hydroxyalkyl)-terminated polydimethylsiloxane is:

,

Wherein, the number of repeating units n is 10-300;

2) Dissolve the chain extender in an ultra-dry solvent, add triethylamine, centrifuge to take the supernatant, add dropwise to the diisocyanate, ice-water bath, inert gas protection, continue to react after the dropwise addition; The chain agent is a diamine chain extender containing catechol functional groups, and its chemical structure is:

3) There are two methods for this step:

Method a): Dissolve the silicone resin in step 1) in an ultra-dry solvent, add dropwise to the reaction system of step 2) under the protection of argon in an ice-water bath, continue the reaction after the dropwise addition, and control the silicone resin: expand Chain agent:

The diisocyanate molar ratio is 1:a:1+a, where 0<a≤1;

Method b): Dissolve the silicone resin in step 1 in an ultra-dry solvent, add the product obtained in step 2) dropwise under argon protection, after the dropwise addition, add dibutyltin dilaurate catalyst, heat to 70 ~90°C, continue the reaction, control the molar ratio of silicone resin:chain extender:diisocyanate to 1:a:1+a, where 0<a≤1;

4) After the reaction, pour the obtained reaction system into deionized water for precipitation, dissolve it again with an organic solvent, pour it into deionized water for precipitation, repeatedly dissolve the precipitate, put it into vacuum drying, and obtain the product;

5) The product of step 4) is dissolved in an organic solvent, and coated on a polished metal substrate, and the coating is obtained after the solvent evaporates.

Further, the method for removing moisture in step 1) is: vacuuming at 120° C. for 2 to 4 hours.

3. The preparation method of an intrinsic type in-situ self-repairing anticorrosion polymer according to claim 1, characterized in that, the ultra-dry solvent described in step 2) is ultra-dry N,N-dimethylformamide Or one of ultra-dry N,N-dimethylacetamide or a mixture of several of them.

Further, the diisocyanate described in step 2) includes toluene diisocyanate, diphenylmethane diisocyanate, terexylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane- One or a mixture of several 4,4'-diisocyanates.

Further, the preparation method of the chain extender described in step 2) is:

1) Dissolve (S)-2,6-di-tert-butoxycarbonylaminocaproic acid in dichloromethane, add excess N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl base) carbodiimide hydrochloride, reacted at room temperature under the protection of an inert gas, then extracted, took the organic phase to dry, and rotary evaporated to obtain the product 1;

2) Dissolving the product 1 in methanol, adding dopamine hydrochloride and triethylamine, reacting under the protection of an inert gas, and removing the solvent by rotary evaporation;

3) Add hydrogen chloride/ethyl acetate solution to the above product, stir and react under the protection of an inert gas, then remove the solvent by rotary evaporation, add ethyl acetate to dissolve the product, extract, dry the organic phase, remove the solvent by rotary evaporation, and obtain the product after drying chain extender.

The preparation method of an intrinsic in-situ self-healing anticorrosion polymer according to claim 1, characterized in that the molar ratio of chain extender to triethylamine in step 2) is 1:1-2.

Further, the ultra-dry solvent in step 3) is one or a mixture of ultra-dry tetrahydrofuran, ultra-dry dichloromethane, and ultra-dry chloroform.

Further, the reaction time of step 2) is 2-5 hours.

Further, the reaction time of step 3) method a) is 12-24h.

Further, the reaction time of step 3) method b) is 2-5 hours.

Further, the organic solvent in step 4) and step 5) is one or more of tetrahydrofuran, dichloromethane, chloroform, N,N-dimethylformamide or N,N-dimethylacetamide mixture. .

The beneficial effects of the present invention are:

1. The silicone resin containing hydrophobic silicon-oxygen bonds can provide hydrophobicity of the coating and enhance the anti-corrosion performance of the coating. In addition, the urethane bond or urea bond formed by the reaction of the amine group or hydroxyl group in the silicone resin with the isocyanate can form a hydrogen bond, improve the mechanical properties and promote self-healing.

2. The diamine chain extender containing catechol groups can improve the adhesion of the silicone coating on the substrate through the strong interaction between the catechol group and the metal substrate on the one hand, and improve the anti-corrosion performance; On the one hand, when the corrosion electrochemical reaction occurs at the coating damage, the microenvironment is alkaline and Fe ³⁺ is generated, and Fe ³⁺ forms a metal coordination bond with the catechol group in situ under the alkaline environment, endowing Coating self-healing anti-corrosion performance.

3. Control silicone resin: chain extender: diisocyanate molar ratio is 1: a: 1+a (0<a≤1), and the polymerization is made by regulating the relative content of hydrogen bond and catechol group in the polymer The material has excellent strength, toughness, adhesion and self-repairing anti-corrosion performance at the same time, and the technical effect of the present invention must be realized within this range.

Description of drawings

In order to make the purpose, technical scheme and beneficial effect of the present invention clearer, the present invention provides the following drawings:

Figure 1 is a schematic diagram of the principle of intrinsic self-healing anticorrosion.

Fig. 2 is the photo after soaking in 3.5% saline solution for 48h; (a) the control example; (b) the coating prepared by the intrinsic self-healing anticorrosion polymer prepared in Example 1.

Fig. 3 is a scanning electron microscope picture after soaking in 3.5% saline solution for 7 days; (a) a control example; (b) a coating prepared by the intrinsic self-healing anticorrosion polymer prepared in Example 1.

Fig. 4 is the test result of the water contact angle of the polymer coating prepared in Example 1.

Detailed ways

The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Self-repairing anti-corrosion principle: As shown in Figure 1, when the ordinary anti-corrosion coating is damaged, the corrosive medium penetrates through the damaged part and contacts the metal substrate, thereby corroding the metal substrate. For the prepared intrinsic type self-healing anti-corrosion coating, when the corrosive medium penetrates through the damaged part and the corrosion electrochemical reaction occurs, Fe ³⁺ and OH ^- are produced, and Fe ³⁺ and phthalate in the polymer at the scratch The phenolic functional groups form dynamic metal coordination cross-linking under alkaline conditions, the scratches repair spontaneously, form a barrier layer again, and restore the anti-corrosion function of the coating. The preparation method of the intrinsic in-situ self-healing anti-corrosion coating is simple, without adding self-healing microcapsules or microspheres, and only using the substances produced by the corrosion electrochemical reaction can realize the in-situ repair of damage and restore the anti-corrosion function.

Example 1

1) Bis(3-aminopropyl)-terminated polydimethylsiloxane (5000g/mol, CAS number:

106214-84-0) Vacuumize at 120°C for 2 hours to remove moisture and cool down to room temperature.

2) Dissolve 0.071 g of a diamine chain extender containing catechol groups in ultra-dry N,N-dimethylformamide, add 0.040 g of triethylamine, and centrifuge to obtain the supernatant. Add dropwise to 0.27g isophorone diisocyanate, ice-water bath, argon protection, react while adding dropwise, continue to react for 3h after dropwise addition;

3) Dissolve 5.0 g of bis(3-aminopropyl)-terminated polydimethylsiloxane after dehydration in 20 mL of ultra-dry tetrahydrofuran, and add it dropwise to the above reaction solution under the protection of argon in an ice-water bath, dropwise Stir while adding, and continue to react for 20h after the dropwise addition.

4) After the reaction, the solution was slowly poured into deionized water for precipitation, dissolved again in tetrahydrofuran, poured into deionized water for precipitation, and after repeated dissolution of the precipitate 3 times, it was put into vacuum drying to obtain the product.

5) The above product is dissolved in tetrahydrofuran, coated on a polished metal substrate, and the coating is obtained after the solvent evaporates.

The preparation method of the diamine chain extender containing catechol group in step 2) is:

Dissolve (S)-2,6-di-tert-butoxycarbonylaminocaproic acid in dichloromethane, add excess N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl) Carbodiimide hydrochloride was protected by an inert gas, stirred in an ice-water bath, raised to room temperature and continued to react for 6 hours. Then add deionized water for extraction, take the organic phase to dry, and rotary evaporate to obtain product 1; dissolve product 1 in methanol, add dopamine hydrochloride and triethylamine, wherein the molar ratio of product 1: dopamine hydrochloride: triethylamine is 1: 1.2:1.5, feed inert gas, react at room temperature for 12 hours, and then remove the solvent by rotary evaporation; add hydrogen chloride/ethyl acetate solution to the above product, the concentration is 4mol/L, feed inert gas, and stir at room temperature for 3 Hour. Afterwards, the solvent was removed by rotary evaporation, ethyl acetate was added to dissolve the product, and extracted with deionized water, the organic phase was dried, the solvent was removed by rotary evaporation, and the product was dried in a vacuum oven to obtain a diamine chain extender containing catechol groups .

In this embodiment, the molar ratio of chain extender to triethylamine is 1:2, and the molar ratio of silicone resin:chain extender:diisocyanate is 1:0.2:1.2.

Example 2

1) Vacuumize bis(3-aminopropyl)-terminated polydimethylsiloxane (2000 g/mol, CAS number: 106214-84-0) at 120° C. for 2 hours to remove moisture, and cool down to room temperature.

2) Dissolve 0.14g of a diamine chain extender containing catechol groups in ultra-dry N,N-dimethylacetamide, add 0.081g of triethylamine, and centrifuge to take the supernatant. Add dropwise to 0.53g isophorone diisocyanate, ice water bath, argon protection, react while adding dropwise, continue to react for 3h after the dropwise addition;

3) Dissolve 4.0 g of bis(3-aminopropyl)-terminated polydimethylsiloxane after dehydration in 50 mL of ultra-dry tetrahydrofuran, and add it dropwise to the above reaction solution under the protection of argon in an ice-water bath. Stir while adding, and continue to react for 18h after the dropwise addition.

4) After the reaction, the solution was slowly poured into deionized water for precipitation, dissolved again in tetrahydrofuran, poured into deionized water for precipitation, and after repeated dissolution of the precipitate 3 times, it was put into vacuum drying to obtain the product.

5) The above product is dissolved in tetrahydrofuran, coated on a polished metal substrate, and the coating is obtained after the solvent evaporates.

The preparation method of the diamine chain extender containing catechol group in step 2) is:

Dissolve (S)-2,6-di-tert-butoxycarbonylaminocaproic acid in dichloromethane, add excess N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl) Carbodiimide hydrochloride was protected by an inert gas, stirred in an ice-water bath, raised to room temperature and continued to react for 4 hours. Then add deionized water for extraction, take the organic phase to dry, and rotary evaporate to obtain product 1; dissolve product 1 in methanol, add dopamine hydrochloride and triethylamine, wherein the molar ratio of product 1: dopamine hydrochloride: triethylamine is 1: 1.5:1.5, feed inert gas, react at room temperature for 15 hours, and then remove the solvent by rotary evaporation; add hydrogen chloride/ethyl acetate solution to the above product, the concentration is 3mol/L, feed inert gas, and stir at room temperature for 5 Hour. Afterwards, the solvent was removed by rotary evaporation, ethyl acetate was added to dissolve the product, and extracted with deionized water, the organic phase was dried, the solvent was removed by rotary evaporation, and the product was dried in a vacuum oven to obtain a catechol-based diamine chain extender.

In this embodiment, the molar ratio of chain extender to triethylamine is 1:2, and the molar ratio of silicone resin:chain extender:diisocyanate is 1:0.2:1.2.

Example 3

1) Vacuumize bis(3-aminopropyl)-terminated polydimethylsiloxane (2000 g/mol, CAS number: 106214-84-0) at 120° C. for 2 hours to remove moisture, and cool down to room temperature.

2) Dissolve 0.35 g of a diamine chain extender containing catechol groups in ultra-dry N,N-dimethylformamide, add 0.15 g of triethylamine, and centrifuge to obtain the supernatant. Add dropwise to 0.67g isophorone diisocyanate, ice water bath, argon protection, react while adding dropwise, continue to react for 2h after dropwise addition;

3) Dissolve 4.0 g of bis(3-aminopropyl)-terminated polydimethylsiloxane after dehydration in 40 mL of ultra-dry tetrahydrofuran, and add it dropwise to the above reaction solution under the protection of argon in an ice-water bath, while dripping Stir while adding, and continue to react for 12h after the dropwise addition.

4) After the reaction, the solution was slowly poured into deionized water for precipitation, dissolved again in tetrahydrofuran, poured into deionized water for precipitation, and after repeated dissolution of the precipitate 3 times, it was put into vacuum drying to obtain the product.

5) The above product is dissolved in tetrahydrofuran, coated on a polished metal substrate, and the coating is obtained after the solvent evaporates.

The preparation method of the diamine chain extender containing catechol group in step 2) is:

Dissolve (S)-2,6-di-tert-butoxycarbonylaminocaproic acid in dichloromethane, add excess N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl) Carbodiimide hydrochloride was protected by an inert gas, stirred in an ice-water bath, raised to room temperature and continued to react for 8 hours. Then add deionized water for extraction, take the organic phase to dry, and rotary evaporate to obtain product 1; dissolve product 1 in methanol, add dopamine hydrochloride and triethylamine, wherein the molar ratio of product 1: dopamine hydrochloride: triethylamine is 1: 1:1.2, feed inert gas, react at room temperature for 20 hours, and then remove the solvent by rotary evaporation; add hydrogen chloride/ethyl acetate solution to the above product, the concentration is 1mol/L, feed inert gas, and stir at room temperature for 6 Hour. Afterwards, the solvent was removed by rotary evaporation, ethyl acetate was added to dissolve the product, and extracted with deionized water, the organic phase was dried, the solvent was removed by rotary evaporation, and the product was dried in a vacuum oven to obtain a catechol-based diamine chain extender.

In this embodiment, the molar ratio of chain extender to triethylamine is 1:1.5, and the molar ratio of silicone resin:chain extender:diisocyanate is 1:0.5:1.5.

Example 4

1) Vacuumize bis(3-aminopropyl)-terminated polydimethylsiloxane (4000 g/mol, CAS number: 106214-84-0) at 120° C. for 2 hours to remove moisture, and cool down to room temperature.

2) Dissolve 0.035 g of a diamine chain extender containing catechol groups in ultra-dry N,N-dimethylformamide, add 0.020 g of triethylamine, and centrifuge to obtain the supernatant. Add dropwise to 0.55g of dicyclohexylmethane diisocyanate, ice-water bath, argon protection, react while adding dropwise, continue to react for 4h after dropwise addition;

3) Dissolve 8.0 g of bis(3-aminopropyl)-terminated polydimethylsiloxane after dehydration in 80 mL of ultra-dry tetrahydrofuran, and add it dropwise to the above reaction solution under the protection of argon in an ice-water bath, while dripping Stir while adding, and continue to react for 24h after the dropwise addition.

4) After the reaction, the solution was slowly poured into deionized water for precipitation, dissolved again in tetrahydrofuran, poured into deionized water for precipitation, and after repeated dissolution of the precipitate 3 times, it was put into vacuum drying to obtain the product.

5) The above product is dissolved in tetrahydrofuran, coated on a polished metal substrate, and the coating is obtained after the solvent evaporates.

The preparation method of the diamine chain extender containing catechol group in step 2) is:

Dissolve (S)-2,6-di-tert-butoxycarbonylaminocaproic acid in dichloromethane, add excess N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl) Carbodiimide hydrochloride was protected by an inert gas, stirred in an ice-water bath, raised to room temperature and continued to react for 5 hours. Then add deionized water for extraction, take the organic phase to dry, and rotary evaporate to obtain product 1; dissolve product 1 in methanol, add dopamine hydrochloride and triethylamine, wherein the molar ratio of product 1: dopamine hydrochloride: triethylamine is 1: 1.2:2, feed inert gas, react at room temperature for 12 hours, and then remove the solvent by rotary evaporation; add hydrogen chloride/ethyl acetate solution to the above product, the concentration is 4mol/L, feed inert gas, and stir at room temperature for 3 Hour. Afterwards, the solvent was removed by rotary evaporation, ethyl acetate was added to dissolve the product, and extracted with deionized water, the organic phase was dried, the solvent was removed by rotary evaporation, and the product was dried in a vacuum oven to obtain a catechol-based diamine chain extender.

In this embodiment, the molar ratio of the chain extender to triethylamine is 1:2, and the molar ratio of silicone resin:chain extender:diisocyanate is 1:0.05:1.05.

Example 5

1) Vacuumize bis(hydroxyalkyl)-terminated polydimethylsiloxane (4000 g/mol, CAS number: 156327-07-0) at 120° C. for 2 hours to remove moisture, and cool down to room temperature.

2) Dissolve 0.071 g of a diamine chain extender containing catechol groups in ultra-dry N,N-dimethylformamide, add 0.020 g of triethylamine, and centrifuge to obtain the supernatant. Add dropwise to 0.58g dicyclohexylmethane diisocyanate, ice-water bath, argon protection, react while adding dropwise, continue to react for 3h after dropwise addition;

3) Dissolve 20.0 g of double-terminal hydroxyl silicone resin after water removal in 60 mL of ultra-dry tetrahydrofuran, and add dropwise to the above reaction solution under the protection of argon. After the dropwise addition, add dibutyltin dilaurate catalyst, heat to 70°C, continue to react for 5h;

4) After the reaction, the solution was slowly poured into deionized water for precipitation, dissolved again in tetrahydrofuran, poured into deionized water for precipitation, and after repeated dissolution of the precipitate 3 times, it was put into vacuum drying to obtain the product.

5) The above product is dissolved in tetrahydrofuran, coated on a polished metal substrate, and the coating is obtained after the solvent evaporates.

The preparation method of the diamine chain extender containing catechol group in step 2) is:

Dissolve (S)-2,6-di-tert-butoxycarbonylaminocaproic acid in dichloromethane, add excess N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl) Carbodiimide hydrochloride was protected by an inert gas, stirred in an ice-water bath, raised to room temperature and continued to react for 5 hours. Then add deionized water for extraction, take the organic phase to dry, and rotary evaporate to obtain product 1; dissolve product 1 in methanol, add dopamine hydrochloride and triethylamine, wherein the molar ratio of product 1: dopamine hydrochloride: triethylamine is 1: 2:2, pass inert gas, react at room temperature for 8 hours, and then remove the solvent by rotary evaporation; add hydrogen chloride/ethyl acetate solution to the above product, the concentration is 4mol/L, pass inert gas, stir reaction at room temperature 2 Hour. Afterwards, the solvent was removed by rotary evaporation, ethyl acetate was added to dissolve the product, and extracted with deionized water, the organic phase was dried, the solvent was removed by rotary evaporation, and the product was dried in a vacuum oven to obtain a catechol-based diamine chain extender.

In this embodiment, the molar ratio of chain extender to triethylamine is 1:1, and the molar ratio of silicone resin:chain extender:diisocyanate is 1:0.1:1.1.

Example 6

1) Vacuumize bis(hydroxyalkyl)-terminated polydimethylsiloxane (20000 g/mol, CAS number: 156327-07-0) at 120° C. for 4 hours to remove moisture, and cool down to room temperature.

2) Dissolve 0.35 g of a diamine chain extender containing catechol groups in ultra-dry N,N-dimethylformamide, add 0.12 g of triethylamine, and centrifuge to obtain the supernatant. Add dropwise to 0.34g hexamethylene diisocyanate, ice-water bath, argon protection, react while adding dropwise, continue to react for 5h after dropwise addition;

3) Dissolve 20.0 g of double-terminated hydroxyl silicone resin after water removal in 100 mL of ultra-dry tetrahydrofuran, and add it dropwise to the above reaction solution under the protection of argon. After the addition is completed, add dibutyltin dilaurate catalyst, and heat To 80°C, continue to react for 5h;

4) After the reaction, the solution was slowly poured into deionized water for precipitation, dissolved again in tetrahydrofuran, poured into deionized water for precipitation, and after repeated dissolution of the precipitate 3 times, it was put into vacuum drying to obtain the product.

5) The above product is dissolved in tetrahydrofuran, coated on a polished metal substrate, and the coating is obtained after the solvent evaporates.

The preparation method of the diamine chain extender containing catechol group in step 2) is:

Dissolve (S)-2,6-di-tert-butoxycarbonylaminocaproic acid in dichloromethane, add excess N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl) Carbodiimide hydrochloride was protected by an inert gas, stirred in an ice-water bath, raised to room temperature and continued to react for 5 hours. Then add deionized water for extraction, take the organic phase to dry, and rotary evaporate to obtain product 1; dissolve product 1 in methanol, add dopamine hydrochloride and triethylamine, wherein the molar ratio of product 1: dopamine hydrochloride: triethylamine is 1: 1:1.2, feed inert gas, react at room temperature for 15 hours, and then remove the solvent by rotary evaporation; add hydrogen chloride/ethyl acetate solution to the above product, the concentration is 3mol/L, feed inert gas, and stir at room temperature for 5 Hour. Afterwards, the solvent was removed by rotary evaporation, ethyl acetate was added to dissolve the product, and extracted with deionized water, the organic phase was dried, the solvent was removed by rotary evaporation, and the product was dried in a vacuum oven to obtain a catechol-based diamine chain extender.

In this embodiment, the molar ratio of chain extender to triethylamine is 1:1.2, and the molar ratio of silicone resin:chain extender:diisocyanate is 1:1:2.

Comparative example 1

1) Vacuumize bis(3-aminopropyl)-terminated polydimethylsiloxane (4000 g/mol, CAS No. 106214-84-0) at 120° C. for 4 hours to remove moisture and cool down to room temperature.

2) Dissolve 0.71 g of a diamine chain extender containing catechol groups in ultra-dry N,N-dimethylformamide, add 0.36 g of triethylamine, and centrifuge to obtain the supernatant. Add dropwise to 0.79g of dicyclohexylmethane diisocyanate, ice water bath, argon protection, react while adding dropwise, continue to react for 5h after dropwise addition;

3) Dissolve 4.0 g of bis(3-aminopropyl)-terminated polydimethylsiloxane after dehydration in 20 mL of ultra-dry tetrahydrofuran, and add it dropwise to the above reaction solution under the protection of argon in an ice-water bath, while dripping Stir while adding, and continue to react for 24h after the dropwise addition.

4) After the reaction is finished, the solution is slowly poured into deionized water for precipitation, and dissolved again with tetrahydrofuran, the synthesized polymer swells and does not dissolve, and the coating cannot be prepared.

The preparation method of the diamine chain extender containing catechol group in step 2) is:

Dissolve (S)-2,6-di-tert-butoxycarbonylaminocaproic acid in dichloromethane, add excess N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl) Carbodiimide hydrochloride was protected by an inert gas, stirred in an ice-water bath, raised to room temperature and continued to react for 5 hours. Then add deionized water for extraction, take the organic phase to dry, and rotary evaporate to obtain product 1; dissolve product 1 in methanol, add dopamine hydrochloride and triethylamine, wherein the molar ratio of product 1: dopamine hydrochloride: triethylamine is 1: 1:1.2, pass inert gas, react at room temperature for 15 hours, and then remove the solvent by rotary evaporation; add hydrogen chloride/ethyl acetate solution to the above product, the concentration is 3mol/L, pass inert gas, and stir at room temperature for 5 Hour. Afterwards, the solvent was removed by rotary evaporation, ethyl acetate was added to dissolve the product, and extracted with deionized water, the organic phase was dried, the solvent was removed by rotary evaporation, and the product was dried in a vacuum oven to obtain a catechol-based diamine chain extender.

In this example, the molar ratio of chain extender to triethylamine is 1:1.8, and the molar ratio of silicone resin:chain extender:diisocyanate is 1:2:3. Since the chain extender is not within the molar ratio range of silicone resin:chain extender:diisocyanate claimed in the present invention, the amount of chain extender added is too much, too many catechol groups are introduced, and oxidative crosslinking is prone to occur. The synthesized polymer swells and does not dissolve, making it impossible to prepare a coating and proceed to subsequent steps.

Comparative example 2

1) Vacuumize bis(3-aminopropyl)-terminated polydimethylsiloxane (5000 g/mol, CAS No. 106214-84-0) at 120° C. for 2 hours to remove moisture, and cool down to room temperature.

2) Dissolve 5 g of bis(3-aminopropyl)-terminated polydimethylsiloxane after dehydration in 20 mL of ultra-dry tetrahydrofuran, and add 0.22 g of isophorone diisocyanate dropwise under the protection of argon in an ice-water bath During the dropwise addition, stirring was continued, and the reaction was continued for 20 h after the dropwise addition was completed.

3) After the reaction, the solution was slowly poured into deionized water for precipitation, dissolved again in tetrahydrofuran, poured into deionized water for precipitation, and after repeated dissolution of the precipitate 3 times, it was put into vacuum drying to obtain the product. 4) The above product is dissolved in tetrahydrofuran, coated on a polished metal substrate, and the coating is obtained after the solvent evaporates.

This comparative example does not have the step of adding a chain extender.

test case 1

Scratch the metal surface coating with a blade, soak it in 3.5wt% NaCl solution, and observe the metal corrosion near the scratch with a microscope. Fig. 2 is the optical microscope test result after soaking 48h of embodiment 1 and comparative example 1, (a) is the coating obtained in comparative example 2; (b) is the intrinsic type self-healing anticorrosion polymerization prepared in embodiment 1 Coatings prepared from materials.

It can be seen from Figure 2 that after soaking in salt water for 48 hours, the scratches of Comparative Example 2 were obviously rusted, while the scratches of the intrinsic self-healing anti-corrosion coating sample prepared in Example 1 were still free of corrosion.

It can be seen that the coating prepared in Example 1 has excellent self-healing and anti-corrosion performance, because the catechol group in the polymer reacts with the Fe ³⁺ generated by the electrochemical corrosion reaction to spontaneously form a metal coordination crosslink structure, repair scratches, and prevent further corrosion. However, in comparative example 2, since no diamine chain extender containing catechol groups is added, it cannot form a metal coordination cross-linking structure with Fe3 ⁺ generated by corrosion electrochemical reaction, scratches cannot be repaired, and there is no self-repairing anti-corrosion effect. corrosion performance.

test case 2

The coatings of Example 1 and Comparative Example 1 soaked in saline solution were placed under a scanning electron microscope to observe the repair of scratches. Figure 3 is the scanning electron microscope test result after soaking for 7 days. (a) is the coating of Comparative Example 2; (b) the coating prepared by the intrinsic self-healing anticorrosion polymer prepared in Example 1.

It can be seen from Figure 3 that after soaking in salt water for 7 days, the scratches in Comparative Example 2 still existed and did not disappear, while the scratches in the intrinsic self-healing anticorrosive coating sample prepared in Example 1 disappeared.

It can be seen that the damage of the coating prepared in Example 1 was repaired after soaking in salt water. This is because the catechol group in the polymer and the Fe ³⁺ produced by the electrochemical corrosion reaction form a metal coordination crosslinking structure. It can close the scratch, repair the damage, prevent the contact between the corrosive medium and the metal substrate, and play a role of self-repair and anti-corrosion. In Comparative Example 2, because no diamine chain extender containing catechol groups was added, the metal coordination cross-linking structure could not be re-formed with Fe ³⁺ at the damaged interface, and the scratches could not be closed, so there was no ability to repair the scratches. Ability to restore corrosion protection properties.

Test case 3

Fig. 4 is the test result of the water contact angle of the polymer coating prepared in Example 1. It can be seen from Figure 4 that the contact angle of the intrinsic in-situ self-repairing anticorrosion resin sample prepared by the present invention is 108°, and its good hydrophobic effect provides guarantee for anticorrosion performance. This is because the silicon-oxygen bond provides a good low surface energy, which makes the coating have excellent hydrophobicity, prevents the penetration of the corrosive medium into the coating, and further improves the corrosion resistance.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be described in terms of form and Various changes may be made in the details without departing from the scope of the invention defined by the claims.

Claims (10)

1. a preparation method of intrinsic type self-repairing anticorrosion polymer in situ, it is characterized in that, the steps are as follows: 1) removing moisture from the silicone resin, which is bis(3-aminopropyl)-terminated polydimethylsiloxane or bis(hydroxyalkyl)-terminated polydimethylsiloxane; The chemical structure of bis(3-aminopropyl)-terminated polydimethylsiloxane is: Wherein, the number of repeating units n is 10-300; The chemical structure of bis(hydroxyalkyl)-terminated polydimethylsiloxane is: Wherein, the number of repeating units n is 10-300; 2) Dissolve the chain extender in an ultra-dry solvent, add triethylamine, centrifuge to take the supernatant, add dropwise to the diisocyanate, ice-water bath, inert gas protection, continue to react after the dropwise addition; The chain agent is a diamine chain extender containing catechol functional groups, and its chemical structure is: 3) There are two methods for this step: Method a): Dissolve the silicone resin in step 1) in an ultra-dry solvent, add dropwise to the reaction system of step 2) under the protection of argon in an ice-water bath, continue the reaction after the dropwise addition, and control the silicone resin: expand The chain agent: diisocyanate molar ratio is 1:a:1+a, where 0<a≤1; Method b): Dissolve the silicone resin in step 1 in an ultra-dry solvent, add the product obtained in step 2) dropwise under argon protection, after the dropwise addition, add dibutyltin dilaurate catalyst, heat to 70 ~90°C, continue the reaction, control the molar ratio of silicone resin:chain extender:diisocyanate to 1:a:1+a, where 0<a≤1; 4) After the reaction, the obtained reaction system is poured into deionized water for precipitation, dissolved again with an organic solvent, poured into deionized water for precipitation, and after repeated dissolution of the precipitate, it is vacuum-dried to obtain the product; 5) The product of step 4) is dissolved in an organic solvent, and coated on a polished metal substrate, and the coating is obtained after the solvent evaporates. 2. The preparation method of an intrinsic in-situ self-healing anticorrosion polymer according to claim 1, characterized in that the method of removing moisture in step 1) is: vacuuming at 120° C. for 2 to 4 hours. 3. the preparation method of a kind of intrinsic type in-situ self-repairing anticorrosion polymer according to claim 1, is characterized in that, step 2) described ultra-dry solvent is ultra-dry N,N-dimethylformamide Or one of the ultra-dry N,N-dimethylacetamide or a mixture of several thereof; the diisocyanate described in step 2) includes toluene diisocyanate, diphenylmethane diisocyanate, terexylylene diisocyanate One or a mixture of isocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate. 4. the preparation method of a kind of intrinsic type in-situ self-repairing anticorrosion polymer according to claim 1, is characterized in that, the preparation method of the chain extender described in step 2) is: 1) Dissolve (S)-2,6-di-tert-butoxycarbonylaminocaproic acid in dichloromethane, add excess N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl base) carbodiimide hydrochloride, reacted at room temperature under the protection of an inert gas, then extracted, took the organic phase to dry, and rotary evaporated to obtain the product 1; 2) Dissolving the product 1 in methanol, adding dopamine hydrochloride and triethylamine, reacting under the protection of an inert gas, and removing the solvent by rotary evaporation; 3) Add hydrogen chloride/ethyl acetate solution to the above product, stir and react under the protection of an inert gas, then remove the solvent by rotary evaporation, add ethyl acetate to dissolve the product, extract, dry the organic phase, remove the solvent by rotary evaporation, and obtain the product after drying chain extender. 5. The preparation method of an intrinsic in-situ self-healing anticorrosion polymer according to claim 1, characterized in that the molar ratio of the chain extender to triethylamine in step 2) is 1:1-2. 6. the preparation method of a kind of intrinsic type in-situ self-repairing anticorrosion polymer according to claim 1, is characterized in that, the ultra-dry solvent of step 3) is ultra-dry tetrahydrofuran, ultra-dry dichloromethane, ultra-dry three One or a mixture of several types of methyl chloride. 7. The preparation method of an intrinsic in-situ self-healing anticorrosion polymer according to claim 1, characterized in that the reaction time of step 2) is 2 to 5 hours. 8 . The preparation method of an intrinsic in-situ self-healing anticorrosion polymer according to claim 1 , wherein the reaction time of step 3) method a) is 12 to 24 hours. 9. The preparation method of an intrinsic in-situ self-healing anticorrosion polymer according to claim 1, characterized in that the reaction time of step 3) and method b) is 2 to 5 hours. 10. the preparation method of a kind of intrinsic type in-situ self-repairing anticorrosion polymer according to claim 1, is characterized in that, the organic solvent of step 4) and step 5) is THF, dichloromethane, trichloromethane, One or a mixture of N,N-dimethylformamide or N,N-dimethylacetamide.