A self-healing polyurea film capable of underwater non-contact repair and its preparation method

Abstract

This invention discloses an underwater non-contact self-healing polyurea film and its preparation method. The film is made of a siloxane block copolymer, a polyurea with a dynamic urea bond structure, and carbon nanomaterials. The underwater non-contact self-healing polyurea coating is prepared using a two-component spraying method. This invention utilizes the dynamic nature of the urea bonds formed by the reaction of amines and isocyanates, and the hydrogen bonds formed between these urea bonds, to endow the elastomer / coating with excellent self-healing properties. Scratches can self-heal within 30 minutes at 80°C. After mechanical damage, it can achieve self-healing in water and seawater. The introduction of carbon nanomaterials endows the material with good photothermal effects, enabling it to generate heat spontaneously under 659nm red light irradiation, achieving non-contact self-heating and enabling the coating to achieve rapid underwater non-contact self-healing. The two-component spraying solution prepared using a prepolymerization method has a certain viscosity, and the rapid reaction between amines and isocyanates allows for rapid curing after spraying to form a protective coating.

Description

Technical Field

[0001] This invention relates to the field of self-healing materials technology, and in particular to an underwater non-contact self-healing polyurea film and its preparation method. Background Technology

[0002] Polyurea is a class of polymeric materials based on isocyanate chemistry, widely used in military, construction, navigation, aviation, and aerospace fields due to its excellent physical and chemical properties. However, due to the complex operating environment, polyurea materials are often subjected to various physical damages (mechanical damage, light, heat, etc.), microbial and chemical corrosion, especially in the marine field. Polyurea coatings, as a commonly used waterproof protective coating for ships, play a crucial role in protecting ships from seawater corrosion. However, during ship navigation, the coating inevitably suffers damage (such as mechanical scratches, microbial corrosion, and seawater corrosion). Once damaged, seawater may further corrode the hull along the damaged area, endangering navigational safety. The traditional method to solve this problem is to sail the ship into a dry dock for re-peeling and repainting the coating, which not only wastes a great deal of resources but also significantly increases ship operating costs. Therefore, developing polyurea materials capable of autonomously repairing damage in underwater environments is of great significance.

[0003] Self-healing materials can be classified into exogenous and intrinsic types based on their repair mechanism. Due to the limited number of repair cycles, more attention is paid to intrinsic self-healing materials. Existing research often introduces reversible covalent bonds (Diels-Alder, disulfide, hindered urea, imine, borate esters, etc.) and reversible non-covalent bonds (hydrogen bonds, π-π conjugation, metal ion complexation, van der Waals interactions, etc.) into polymer networks to achieve controlled spontaneous healing. However, due to the influence of underwater environments, most current self-healing polyurea materials cannot achieve self-healing in aquatic environments. CN 114716901 A discloses a method for preparing ultra-low water absorption two-component sprayed polyurea, which solves the problem of polyurea coatings aging due to water absorption in humid or long-term immersion environments, but this technology does not possess self-healing properties. CN 115505086A discloses a fast photoresponsive self-healing polyurea material and its preparation method. The resulting photoresponsive self-healing polyurea exhibits a self-healing efficiency approaching 100% after 10 minutes of irradiation with 365nm ultraviolet light and 450nm visible light, demonstrating rapid photoresponsive self-healing performance. However, the strength of the fast photoresponsive self-healing polyurea material prepared by this technology is relatively low, only about 1.2 MPa, and it also lacks underwater self-healing performance. CN 114685756A discloses a high-performance self-healing polyurea and its preparation method. This technology uses terminal amino polyethers as soft segments and alicyclic isocyanates and zigzag-structured diamine chain extenders as hard segments, preparing self-healing polyurea through a one-pot reaction. Introducing dynamic disulfide bonds into the polyurea network endows the polyurea with good self-healing properties. However, its scratches require 2 hours at 120℃ to achieve partial repair, posing a problem of excessively high repair temperature. It also lacks underwater repair performance.

[0004] Based on the above analysis, a method for preparing a self-healing polyurea capable of underwater repair is urgently needed in the industry. Summary of the Invention

[0005] To address the issue that traditional polyurea coatings lack underwater self-healing properties, this invention provides an underwater non-contact self-healing polyurea film and its preparation method.

[0006] This invention is achieved through the following technical means:

[0007] This invention first discloses a method for preparing an underwater non-contact self-healing polyurea film, comprising:

[0008] Carbon nanomaterials were added to the polyurea solution and dispersed by ball milling for 3 hours at 600 r / min. After uniform dispersion, the mixture was poured into a mold and allowed to evaporate the solvent at room temperature for 6 hours. Then, it was dried in an oven at 80°C for 6 hours to obtain a self-healing polyurea film that can be used underwater without contact.

[0009] Furthermore, the carbon material is selected from one of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and carbon black, and the amount added is 0.5wt%-2wt% of the polyurea solution.

[0010] Furthermore, the polyurea solution is prepared by the following method:

[0011] The siloxane-containing block copolymer was dissolved in tetrahydrofuran, and hexamethylene diisocyanate trimer was added. After reacting at room temperature for 2 hours, a polyurea solution was obtained.

[0012] Furthermore, the molar ratio of the siloxane block copolymer to the hexamethylene diisocyanate trimer is 15:1.

[0013] Furthermore, the siloxane-containing block copolymer is prepared by the following method:

[0014] (1) Dissolve the amino-terminated siloxane oligomer in tetrahydrofuran, add diisocyanate multiple times, the molar ratio of the total amount of amino-terminated siloxane oligomer to diisocyanate is 1:2, react for 1 hour at room temperature after each addition of diisocyanate, and continue to react for 2 hours after the last addition of diisocyanate to obtain an amino-terminated siloxane prepolymer solution.

[0015] (2) Dissolve polyetheramine in tetrahydrofuran and add diisocyanate in portions. The molar ratio of polyetheramine to diisocyanate is 2:1. After each addition of diisocyanate, react at room temperature for 1 hour. After the last addition of diisocyanate, continue to react for 2 hours to obtain a polyetheramine prepolymer solution.

[0016] (3) The amino-terminated siloxane prepolymer solution and the polyetheramine prepolymer solution were mixed at a molar ratio of 1:1.2 and reacted at room temperature for 6 hours. After removing the solvent by rotary evaporation, a siloxane block copolymer was obtained.

[0017] Furthermore, the diisocyanate is selected from one of naphthalene diisocyanate, isophenyl diisocyanate, terephthalene diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate.

[0018] Furthermore, the amino-terminated siloxane oligomer has a molecular weight of 900-5000, and its molecular structure is as follows:

[0019]

[0020] In the formula, n is 18-40; R1 is one of H, methyl, and ethyl; R2 is one of H, methyl, and ethyl; and the molecular weight of the polyetheramine is 400-2000.

[0021] The present invention also discloses an underwater non-contact self-healing polyurea film prepared according to any of the above preparation methods.

[0022] The present invention also discloses the application of the above-mentioned underwater non-contact self-healing polyurea film in the preparation of anti-corrosion coatings.

[0023] Furthermore, the film is formed using a two-component spraying method during use.

[0024] Furthermore, the two-component spraying method is specifically as follows:

[0025] (1) Preparation of Component 1 Solution:

[0026] ① The amino-terminated siloxane oligomer was dissolved in tetrahydrofuran, and diisocyanate was added in multiple portions. The molar ratio of the total amount of amino-terminated siloxane oligomer to diisocyanate was 1:2. After each addition of diisocyanate, the reaction was carried out at room temperature for 1 hour. After the last addition of diisocyanate, the reaction was continued for 2 hours. Then, carbon nanomaterials were added, and the mixture was dispersed by ball milling for 3 hours (600 r / min) to obtain an amino-terminated siloxane prepolymer solution composed of carbon nanomaterials.

[0027] ② Dissolve polyetheramine in tetrahydrofuran, and add diisocyanate in portions. The molar ratio of polyetheramine to diisocyanate is 2:1. After each addition of diisocyanate, react at room temperature for 1 hour. After the last addition of diisocyanate, continue to react for 2 hours to obtain a polyetheramine prepolymer solution.

[0028] ③ The amino-terminated siloxane prepolymer solution and the polyetheramine prepolymer solution were mixed at a molar ratio of 1:2 and reacted at room temperature for 6 hours. After removing the solvent by rotary evaporation, component 1 of the two-component spray coating was obtained. The content of the carbon nanomaterial was 0.5wt%-2wt%.

[0029] (2) Preparation of solution for component 2:

[0030] ① Dissolve polyetheramine in tetrahydrofuran, add carbon nanomaterials, and disperse using a ball mill for 3 hours at a speed of 600 r / min to obtain a polyetheramine prepolymer solution with carbon nanomaterials.

[0031] ② Diisocyanate was added to a polyetheramine prepolymer solution composed of carbon nanomaterials, with a molar ratio of polyetheramine to diisocyanate of 1:1.2. After reacting at room temperature for 3 hours, hexamethylene diisocyanate trimer was added, with a molar ratio of polyetheramine to hexamethylene diisocyanate trimer of 10:1. The mixture was stirred until homogeneous, and the solvent was removed by rotary evaporation to obtain component 2 in the two-component spray coating. The content of the carbon nanomaterials was 0.5wt%-2wt%.

[0032] (3) Mix components 1 and 2 in a volume ratio of 1:1, spray at a pressure of 3000-4000psi and a temperature of 25℃, and keep the spraying pressure of components 1 and 2 consistent to form a film.

[0033] The beneficial effects of this invention are as follows:

[0034] 1) The urea bonds formed by the reaction of amine and isocyanate and the hydrogen bonds formed between the urea bonds are dynamic, which gives the elastomer / coating good self-healing properties. Scratches can be self-healed within 30 minutes at 80℃.

[0035] 2) The prepared polyurea elastomer contains both dynamic covalent crosslinks and non-covalent hydrogen crosslinks, which gives the prepared polyurea elastomer excellent mechanical properties, with a tensile strength of 30.8 MPa and a Young's modulus of 334.7 MPa.

[0036] 3) The siloxane blocks contained in polyurea have low surface energy and migrate to the surface during film formation, which increases the hydrophobicity of the coating, with a water contact angle of 129.4°.

[0037] 4) The prepared polyurea elastomer / coating has self-healing properties in underwater acoustic environments and can self-repair in water or seawater after mechanical damage.

[0038] 5) The introduction of carbon nanomaterials endows the material with good photothermal effect. It can generate heat on its own under 659nm red light irradiation, realize non-contact self-heating, and realize non-contact rapid self-repair of the coating underwater (1min).

[0039] 6) The two-component spray solution prepared by the prepolymerization method has a certain viscosity, and the amine and isocyanate react rapidly, which can quickly cure to form a protective coating after spraying.

[0040] 7) The prepared polyurea coating contains a large number of hydrogen-bonded groups and polarity, which can form hydrogen bonds and weak van der Waals interactions with the substrate material, further improving the adhesion of the coating. Attached Figure Description

[0041] Figure 1 The resulting polyetheramine / siloxane block copolymer solution.

[0042] Figure 2 This is a dried, underwater self-healing polyurea film.

[0043] Figure 3 The images show micrographs of the prepared underwater non-contact self-healing polyurea film material before and after repair at 80°C. As can be seen from the images, the material can achieve self-repair of scratches within 30 minutes at 80°C.

[0044] Figure 4 The images show micrographs of the prepared underwater non-contact self-healing polyurea film material before and after self-healing in 80°C hot water. As can be seen from the figures, the material can achieve self-healing of scratches within 30 seconds in 80°C water.

[0045] Figure 5 Macroscopic images before and after self-healing and tensile images after repair of the prepared underwater non-contact self-healing polyurea film material in 80°C hot water.

[0046] Figure 6 The stress-strain curves of the prepared underwater non-contact self-healing polyurea film material are shown.

[0047] Figure 7 The curve of surface temperature change of underwater non-contact self-healing polyurea elastomer under 659nm red light irradiation as a function of irradiation time.

[0048] Figure 8 Laser confocal images of a self-healing polyurea elastomer capable of underwater non-contact repair before and after self-healing under 659nm red light irradiation.

[0049] Figure 9 Microscopic images of a non-contact, self-healing polyurea coating underwater in 80°C water before and after self-healing.

[0050] Figure 10 Microscopic images of a self-healing polyurea coating that can be submerged underwater without contact, before and after self-healing under 659nm red light irradiation.

[0051] Figure 11 The stress-strain curves of the prepared self-healing polyurea film before and after self-healing in 80℃ warm water are shown.

[0052] Figure 12 Microscopic images of the self-healing polyurea film before and after scratch self-healing in 80°C warm water.

[0053] Figure 13 Macroscopic images of the underwater gas transmission pipeline assembled from the self-healing polyurea film before and after wound self-healing in water under 659nm red light irradiation.

[0054] Figure 14 Microscopic images of the self-healing polyurea film before and after scratch self-healing in 80°C warm water.

[0055] Figure 15 Microscopic images of the self-healing polyurea coating before and after self-healing under 659nm red light irradiation. Detailed Implementation

[0056] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0057] Example 1

[0058] A method for preparing an underwater non-contact self-healing polyurea film:

[0059] (1) Add 5g of secondary amine-terminated siloxane oligomer (DMS-A211, molecular weight 1000) to a 50mL round-bottom flask, add 10mL of tetrahydrofuran, add 0.555g of isophorone diisocyanate, and stir magnetically at room temperature for 1h. Then add another 0.555g of isophorone diisocyanate and continue the reaction for 1h. Finally, add 1.111g of isophorone diisocyanate and react at room temperature for 2h to obtain an isocyanate-terminated siloxane prepolymer solution. The reaction equation is as follows:

[0060]

[0061] (2) In a separate 50 mL round-bottom flask, add 12 g of polyetheramine (D2000, molecular weight 2000) and 20 mL of tetrahydrofuran, then add 0.667 g of isophorone diisocyanate. After stirring magnetically at room temperature for 1 h, add another 0.667 g of isophorone diisocyanate and continue the reaction for 2 h to obtain a polyetheramine prepolymer solution. The reaction equation is as follows:

[0062]

[0063] (3) The isocyanate-terminated siloxane prepolymer solution and the polyetheramine prepolymer solution obtained in the above steps are mixed and stirred at room temperature for 6 hours to obtain a polyetheramine / siloxane block copolymer solution. The reaction equation is as follows:

[0064]

[0065] (4) Weigh 0.336 g of hexamethylene diisocyanate trimer and dissolve it in 3 mL of tetrahydrofuran. Add the solution dropwise to the above polyetheramine / siloxane block copolymer solution. After the addition is complete, continue the reaction at room temperature for 2 hours. Then pour the solution into a polytetrafluoroethylene mold and dry it at room temperature for 6 hours to evaporate a large amount of solvent. Afterward, transfer it to an 80°C oven and continue drying for 6 hours to obtain an underwater non-contact self-healing polyurea film material. The reaction equation is as follows:

[0066]

[0067] Figure 1 This is a photograph of the polyetheramine / siloxane block copolymer solution prepared in this embodiment.

[0068] Figure 2 This is a photograph of the dried, underwater self-healing polyurea film of this embodiment.

[0069] Figure 3 These are micrographs of the underwater non-contact self-healing polyurea film material prepared in this embodiment before and after repair at 80°C. Figure 3 It is known that this material can achieve self-repair of scratches within 30 minutes at 80℃.

[0070] Figure 4 These are micrographs of the underwater non-contact self-healing polyurea film material prepared in this embodiment before and after self-healing in 80°C hot water. Figure 4 It is known that this material can self-repair scratches within 30 seconds in water at 80℃.

[0071] Figure 5 Macroscopic images of the underwater self-healing polyurea film prepared in this embodiment before and after self-healing in 80°C hot water, and a tensile image after repair. Figure 5 It is known that the damaged polyurea film can quickly repair the wound in warm water at 80℃, and the repaired wound has a certain mechanical strength.

[0072] Figure 6 This is the stress-strain curve of the underwater non-contact self-healing polyurea film material prepared in this embodiment. Figure 6 It can be seen that its fracture stress is 30.8 MPa, its fracture elongation is 100.8%, and its self-healing efficiency is 90%.

[0073] Example 2

[0074] A method for preparing an underwater non-contact self-healing polyurea elastomer:

[0075] (1) Add 5g of secondary amine-terminated siloxane oligomer (DMS-A211, molecular weight 1000) to a 50mL round-bottom flask, add 10mL of tetrahydrofuran, add 0.555g of isophorone diisocyanate, stir magnetically at room temperature for 1h, add another 0.555g of isophorone diisocyanate, continue to react for 1h, add 1.111g of isophorone diisocyanate and react at room temperature for 2h to obtain an isocyanate-terminated siloxane prepolymer solution.

[0076] (2) Take another 50mL round-bottom flask, add 12g of polyetheramine (D2000, molecular weight 2000) and 20mL of tetrahydrofuran, add 0.667g of isophorone diisocyanate, stir magnetically at room temperature for 1h, add another 0.667g of isophorone diisocyanate and continue to react for 2h to obtain polyetheramine prepolymer solution.

[0077] (3) Mix the isocyanate-terminated siloxane prepolymer solution and the polyetheramine prepolymer solution obtained in the above steps, and stir at room temperature for 6 hours to obtain a polyetheramine / siloxane block copolymer solution.

[0078] (4) Weigh 0.336 g of hexamethylene diisocyanate trimer and dissolve it in 3 mL of tetrahydrofuran. Add the solution dropwise to the above polyetheramine / siloxane block copolymer solution. After the addition is complete, continue the reaction at room temperature for 2 hours. Then add 0.105 g of single-walled carbon nanotubes to the solution and disperse them using a ball mill at 600 r / min for 3 h. Then pour the uniformly dispersed solution into a polytetrafluoroethylene mold.

[0079] Figure 7 This is a curve showing the surface temperature of the underwater non-contact self-healing polyurea film prepared in this embodiment as a function of irradiation time under 659 nm red light irradiation. The irradiation intensity is 110 mW / cm². 2 When the irradiation source is removed, the polyurea film can be rapidly heated to 80°C within 20 seconds, with a maximum temperature of 124°C. The film temperature can also be rapidly reduced to room temperature after the irradiation source is removed.

[0080] Figure 8 These are micrographs of the underwater non-contact self-healing polyurea film prepared in this embodiment before and after self-healing under 659nm red light irradiation. The wound healed after 1 minute of 659nm red light irradiation.

[0081] Example 3

[0082] A method for preparing an underwater non-contact self-healing polyurea coating:

[0083] (1) Add 5g of secondary amine-terminated siloxane oligomer (DMS-A211, molecular weight 1000) to a 50mL round-bottom flask, add 10mL of tetrahydrofuran, add 0.555g of isophorone diisocyanate, stir magnetically at room temperature for 1h, add another 0.555g of isophorone diisocyanate, continue to react for 1h, add 1.111g of isophorone diisocyanate and react at room temperature for 2h to obtain the isocyanate-terminated siloxane prepolymer solution.

[0084] (2) Take another 50mL round-bottom flask, add 20g of polyetheramine (D2000, molecular weight 2000) and 20mL of tetrahydrofuran, add 1.111g of isophorone diisocyanate, stir magnetically at room temperature for 1h, add another 1.111g of isophorone diisocyanate and continue to react for 2h to obtain polyetheramine prepolymer solution.

[0085] (3) The isocyanate-terminated siloxane prepolymer solution and polyetheramine prepolymer solution obtained in the above steps are mixed and stirred at room temperature for 6 hours. Then, 0.074 g of single-walled carbon nanotubes are added and dispersed by ball milling at 600 r / min for 3 hours. Tetrahydrofuran is removed by rotary evaporation at 50 °C to finally obtain spraying component 1.

[0086] (4) Take 20g of polyetheramine (D2000, molecular weight 2000) and 20mL of tetrahydrofuran, add 0.074g of single-walled carbon nanotubes, disperse by ball milling at 600r / min for 3h, add 2.666g of isophorone diisocyanate and react at room temperature for 3h, then add 0.336g of hexamethylene diisocyanate trimer, stir evenly and remove tetrahydrofuran by rotary evaporation at 50℃, finally obtain spray component 2.

[0087] (5) Load components 1 and 2 into a two-component spraying device, set the air pressure to 3000psi and the spraying temperature to 25℃, spray them onto the tinplate surface, and leave them at room temperature for 24 hours to obtain an underwater non-contact self-healing polyurea coating.

[0088] Figure 9 These are micrographs of the underwater non-contact self-healing polyurea coating prepared in this embodiment before and after self-healing in 80°C warm water. When immersed in 80°C warm water, scratches on the coating surface can be repaired within 1 minute.

[0089] Figure 10 These are micrographs of the underwater non-contact self-healing polyurea coating prepared in this embodiment before and after self-healing under 659nm red light irradiation. After irradiation with 659nm red light for 1 minute, the scratches on the coating surface were repaired.

[0090] Example 4

[0091] A method for preparing an underwater non-contact self-healing polyurea film:

[0092] (1) Add 5g of secondary amine-terminated siloxane oligomer (DMS-A211, molecular weight 1000) and 5g of primary amine-terminated siloxane oligomer (DMS-A12, molecular weight 1000) to a 50mL round-bottom flask, add 20mL of tetrahydrofuran, add 0.5g of isophorone diisocyanate, stir magnetically at room temperature for 1h, add another 0.5g of isophorone diisocyanate, continue to react for 1h, add 0.778g of isophorone diisocyanate and react at room temperature for 2h to obtain a siloxane prepolymer solution.

[0093] (2) Weigh 0.672g of hexamethylene diisocyanate trimer and dissolve it in 6mL of tetrahydrofuran. Add the solution dropwise to the above siloxane prepolymer solution. After the addition is complete, continue the reaction at room temperature for 6h. Then add 0.063g of single-walled carbon nanotubes and disperse them by ball milling at 600r / min for 3h. Then pour the solution into a polytetrafluoroethylene mold, dry it at room temperature for 6h, and then put it into an 80℃ oven to dry for 6h to obtain an underwater non-contact self-healing polyurea film.

[0094] Figure 11The stress-strain curves of the self-healing polyurea film prepared in this embodiment before and after self-healing in 80°C water are shown. Figure 11 It has been found that immersing the damaged polyurea film in 80℃ warm water for 30 seconds can repair it, with a repair efficiency of over 85%.

[0095] Figure 12 These are micrographs of the self-healing polyurea film prepared in this embodiment before and after scratch self-healing in 80°C warm water. Figure 12 It is known that scratches can be repaired by immersing the damaged polyurea film in 80℃ warm water for 30 seconds.

[0096] Figure 13 Macroscopic images of the underwater gas transmission pipeline assembled from the self-healing polyurea film prepared in this embodiment, before and after wound self-healing under 659nm red light irradiation in water. Figure 13 It is known that gas transmission pipelines assembled from self-healing polyurea films can achieve underwater non-contact self-repair after damage. Repairing the damaged gas transmission pipeline surface can be achieved by irradiating it with 659nm red light for 30 seconds.

[0097] Example 5

[0098] A method for preparing an underwater non-contact self-healing polyurea film:

[0099] (1) Take another 50mL round bottom flask, add 20g of polyetheramine (ED400, molecular weight 400) and 40mL of tetrahydrofuran, add 2.778g of isophorone diisocyanate, stir magnetically at room temperature for 1h, add another 2.778g of isophorone diisocyanate and continue to react for 2h to obtain polyetheramine prepolymer solution.

[0100] (2) Weigh 8.4g of hexamethylene diisocyanate trimer and dissolve it in 10mL of tetrahydrofuran. Then add it dropwise to the polyetheramine prepolymer solution obtained above. After the addition is complete, react at room temperature for 6h. Weigh 0.170g of single-walled carbon nanotubes and disperse them by ball milling at 600r / min for 3h. Then pour the solution into a polytetrafluoroethylene mold, dry it at room temperature for 6h, and then put it into an 80℃ oven to dry for 6h to obtain an underwater non-contact self-healing polyurea film.

[0101] Figure 14 These are micrographs of the self-healing polyurea film prepared in this embodiment before and after scratch self-healing in 80°C warm water. Figure 14 It can be seen that the polyurea elastomer prepared by the modified formula has good underwater self-healing properties. It can achieve self-repair of scratches within 30 seconds in 80℃ warm water.

[0102] Figure 15These are micrographs of the self-healing polyurea coating prepared in this embodiment before and after self-healing under 659nm red light irradiation. Figure 15 It can be seen that the polyurea elastomer prepared by the modified formula has good non-contact underwater self-healing properties. Scratches can be repaired after 1 minute of irradiation with 659nm.

[0103] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing an underwater non-contact self-healing polyurea film, comprising: (1) Preparation of siloxane-containing block copolymers: ① Dissolve the amino-terminated siloxane oligomer in tetrahydrofuran, and add diisocyanate multiple times. The molar ratio of the total amount of amino-terminated siloxane oligomer to diisocyanate is 1:

2. After each addition of diisocyanate, react at room temperature for 1 hour. After the last addition of diisocyanate, continue to react for 2 hours to obtain an amino-terminated siloxane prepolymer solution. ② Dissolve polyetheramine in tetrahydrofuran, and add diisocyanate in portions. The molar ratio of polyetheramine to diisocyanate is 2:

1. After each addition of diisocyanate, react at room temperature for 1 hour. After the last addition of diisocyanate, continue to react for 2 hours to obtain a polyetheramine prepolymer solution. ③ Mix the amino-terminated siloxane prepolymer solution and the polyetheramine prepolymer solution at a molar ratio of 1:1.2, react at room temperature for 6 hours, and remove the solvent by rotary evaporation to obtain the siloxane-containing block copolymer. (2) Preparation of polyurea solution: The siloxane-containing block copolymer was dissolved in tetrahydrofuran, and hexamethylene diisocyanate trimer was added. After reacting at room temperature for 2 hours, a polyurea solution was obtained. (3) Add carbon nanomaterials to the polyurea solution, disperse by ball milling for 3 hours at 600 r / min, and after uniform dispersion, pour into a mold, evaporate the solvent at room temperature for 6 hours, and then dry in an oven at 80℃ for 6 hours to obtain an underwater non-contact self-healing polyurea film; wherein: The carbon nanomaterial is selected from one of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and carbon black, and the amount added is 0.5wt%-2wt% of the polyurea solution. The diisocyanate is selected from one of naphthalene diisocyanate, isophenyl diisocyanate, terephthalene diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate; The amino-terminated siloxane oligomer has a molecular weight of 900-5000 and its molecular structure is as follows: ， In the formula, n is 18-40; R1 is one of H, methyl, and ethyl; R2 is one of H, methyl, and ethyl. The polyetheramine has a molecular weight of 400-2000.

2. The preparation method according to claim 1, wherein: The molar ratio of the siloxane block copolymer to the hexamethylene diisocyanate trimer is 15:

1.

3. An underwater non-contact self-healing polyurea film prepared by the preparation method according to claim 1 or 2.

4. The application of the underwater non-contact self-healing polyurea film according to claim 3 in the preparation of anti-corrosion coatings.

5. The application of an underwater non-contact self-healing polyurea film in the preparation of anti-corrosion coatings, wherein the film is formed by a two-component spraying method during use; wherein: (1) Component 1 is prepared by the following method: ① The amino-terminated siloxane oligomer was dissolved in tetrahydrofuran, and diisocyanate was added in multiple portions. The molar ratio of the total amount of amino-terminated siloxane oligomer to diisocyanate was 1:

2. After each addition of diisocyanate, the reaction was carried out at room temperature for 1 hour. After the last addition of diisocyanate, the reaction was continued for 2 hours. Then, carbon nanomaterials were added and dispersed by ball milling for 3 hours to obtain an amino-terminated siloxane prepolymer solution composed of carbon nanomaterials. ② Dissolve polyetheramine in tetrahydrofuran, and add diisocyanate in portions. The molar ratio of polyetheramine to diisocyanate is 2:

1. After each addition of diisocyanate, react at room temperature for 1 hour. After the last addition of diisocyanate, continue to react for 2 hours to obtain a polyetheramine prepolymer solution. ③ Mix the amino-terminated siloxane prepolymer solution and the polyetheramine prepolymer solution at a molar ratio of 1:2, react at room temperature for 6 hours, and remove the solvent by rotary evaporation to obtain component 1 in the two-component spray coating, with the carbon nanomaterial content being 0.5wt%-2wt%. (2) Component 2 is prepared by the following method: ① Dissolve polyetheramine in tetrahydrofuran, add carbon nanomaterials, and disperse using a ball mill for 3 hours at a speed of 600 r / min to obtain a polyetheramine prepolymer solution with carbon nanomaterials composite. ② Diisocyanate was added to the polyetheramine prepolymer solution of carbon nanomaterial composite, with a molar ratio of polyetheramine to diisocyanate of 1:1.

2. After reacting at room temperature for 3 hours, hexamethylene diisocyanate trimer was added, with a molar ratio of polyetheramine to hexamethylene diisocyanate trimer of 10:

1. The mixture was stirred evenly, and the solvent was removed by rotary evaporation to obtain component 2 in the two-component spray coating. The content of carbon nanomaterial was 0.5wt%-2wt%. (3) Spray component 1 and component 2 at a volume ratio of 1:1; The carbon nanomaterial is selected from one of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and carbon black, and the amount added is 0.5wt%-2wt% of the polyurea solution. The diisocyanate is selected from one of naphthalene diisocyanate, isophenyl diisocyanate, terephthalene diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate; The amino-terminated siloxane oligomer has a molecular weight of 900-5000 and its molecular structure is as follows: ， In the formula, n is 18-40; R1 is one of H, methyl, and ethyl; R2 is one of H, methyl, and ethyl. The polyetheramine has a molecular weight of 400-2000.

6. The application according to claim 5, wherein: The spraying pressure is 3000-4000 psi and the spraying temperature is 25℃.

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