Self-repairing polyurethane film containing disulfide bond and DA bond and preparation method thereof

Abstract

The invention provides a self-repairing polyurethane film containing a disulfide bond and a DA bond and a preparation method thereof, and the preparation method comprises the following steps: (1) adding an organic solvent into a three-necked flask, then dissolving dihydric alcohol, diisocyanate, a disulfide bond monomer and a DA bond forming monomer in the organic solvent, then adding a catalyst, and mechanically stirring uniformly; (2) introducing nitrogen into the three-necked flask to evacuate air, setting a reaction temperature, and carrying out a reaction under mechanical stirring; (3) in a nitrogen environment, dropwise adding a monomer II forming a DA bond into the solution obtained after the reaction in the step (2), and after the dropwise addition of the monomer II forming the DA bond is completed, setting the reaction temperature and reacting for a period of time; and (4) pouring the solution obtained after the reaction in the step (3) into a polytetrafluoroethylene mold, and drying to obtain the self-repairing polyurethane film. The self-repairing polyurethane film prepared by the preparation method disclosed by the invention has relatively good mechanical properties, relatively good self-repairing performance under mild conditions and high self-repairing efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical materials, and in particular to a self-repairing polyurethane film containing disulfide bonds and DA bonds and a preparation method thereof. Background Art

[0002] There are many research results on polyurethane with self-healing properties. The raw materials required for synthesis (the raw materials determine the type of dynamic bonds) and the synthesis methods are also very different. The dynamic bonds that are currently studied more are sulfur-sulfur bonds, ester bonds, hydrogen bonds, etc. Although these dynamic bonds can achieve reversibility under certain temperature conditions to carry out the self-healing process of the material, compared with traditional stable covalent bonds, the bond energy of dynamic bonds is lower, and the introduction of dynamic bonds in polymers will reduce the mechanical properties of the material. Therefore, it is important to improve the mechanical strength of the material while improving the self-healing performance of the material.

[0003] Patent publication CN118878877A reports that a polyurethane with a force-responsive function and a polyurethane with a coordination function with metal ions are mixed by physical blending to obtain a self-reinforced and self-repairing polyurethane film suitable for extreme marine environments, and its tensile strength is between 8MPa-12.4MPa. However, its synthesis process is relatively cumbersome, and it is necessary to first prepare a polyurethane with a force-responsive function, and then prepare a polyurethane with a metal ion coordination function, and then blend the two. Patent publication CN118496546A reports a self-repairing polyurethane elastomer with isocyanate and polyol as soft segments and polytetrahydrofuran as hard segments, adding disulfide covalent bonds, and adjusting the soft segment and hard segment content. The elastomer has good mechanical properties and its fracture strength reaches 9.79MPa. Public patent CN118221907A reports a method of introducing disulfide bonds as chain extenders into hard segments to adjust the mechanical properties and self-healing properties of materials. The tensile strength can reach 7.78MPa at best. The prepolymerization chain extension method is used in the polyurethane synthesis process, which is more cumbersome compared to the one-pot method. The self-healing materials in the above public patents have significant advantages in extending service life and reducing maintenance costs, but their low mechanical strength limits their application in high-load scenarios, such as aerospace, flexible electronics, and medical implants. These scenarios require materials to not only repair damage, but also withstand greater stress and deformation. Therefore, it is crucial to develop self-healing materials with high mechanical strength, which can not only improve the reliability and durability of the materials, but also broaden the scope of application and provide new solutions for the development of high-performance materials. Summary of the invention

[0004] In view of this, the present invention aims to provide a self-healing polyurethane film containing disulfide bonds and DA bonds and a preparation method thereof, so as to solve the problem that the preparation method of polyurethane materials in the prior art is complicated and the prepared polyurethane cannot take into account both high mechanical strength and self-healing performance under mild conditions.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A method for preparing a self-repairing polyurethane film containing disulfide bonds and DA bonds comprises the following steps:

[0007] (1) Add an organic solvent into a three-necked flask, then dissolve the diol, diisocyanate, disulfide bond monomer, and DA bond forming monomer in the organic solvent, then add the catalyst and stir mechanically to mix evenly;

[0008] (2) nitrogen was introduced into the three-necked flask to exhaust the air, the reaction temperature was set, and the reaction was carried out under mechanical stirring;

[0009] (3) Under nitrogen environment, add two drops of DA bond forming monomer to the solution obtained after the reaction in step (2). After the addition of the two drops of DA bond forming monomer is completed, set the reaction temperature and react for a period of time;

[0010] (4) Pour the solution obtained after the reaction in step (3) into a polytetrafluoroethylene mold and dry it to obtain a self-healing polyurethane film.

[0011] The present invention introduces dynamic disulfide bonds into the polyurethane through prepolymerization and chain extension, reacts disulfide bonds with isocyanate groups, and makes the polyurethane have good self-healing properties. Then, a cross-linking reaction is performed to introduce DA bonds, which can further fix the disulfide bonds in the cross-linking network formed by the DA bonds and the polyurethane. On the basis of improving the mechanical strength of the polyurethane film, the breaking and reconstruction of the disulfide bonds are made more stable, thereby improving the self-healing efficiency of the polyurethane.

[0012] Furthermore, the weight ratio of the diol, diisocyanate, disulfide bond monomer, organic solvent, catalyst, DA bond forming monomer one, and DA bond forming monomer two is (1-40): (1-40): (20-60): (0.1-1): (1-40): (1:40).

[0013] The present invention controls the content of each reagent and then the content of the double dynamic bond, so that the prepared polyurethane film can achieve self-repair of scratches within 0.5 hours at a temperature of 80°C. At the same time, the tensile strength of the self-repairing polyurethane film can reach 31MPa, the elastic modulus can reach 20MPa, and the toughness can reach 96 MJ m -3 .

[0014] Furthermore, the molar ratio of the disulfide bond monomer to the DA bond-forming monomer is 1:(0.5-2.5). This setting controls the content of the double dynamic bond by controlling the molar ratio of the disulfide bond monomer to the DA bond-forming monomer, thereby improving the mechanical strength of the self-healing polyurethane film and the self-healing efficiency under mild conditions.

[0015] Furthermore, the molar ratio of the disulfide bond monomer to the DA bond forming monomer is 1:1.

[0016] Furthermore, the diol is one of polytetramethylene ether glycol and polycaprolactone diol. Preferably, the diol is polycaprolactone diol.

[0017] Furthermore, the diisocyanate is one of 1,6-hexamethylene diisocyanate and isophorone diisocyanate. Preferably, the diisocyanate is isophorone diisocyanate.

[0018] Further, the disulfide bond monomer is one or more of dialkyl disulfide, dihydroxytoluene disulfide, and bis(4-hydroxyphenyl) disulfide. Preferably, the disulfide bond monomer is one or more of bis(4-hydroxyphenyl) disulfide and dialkyl disulfide. More preferably, the disulfide bond monomer is bis(4-hydroxyphenyl) disulfide.

[0019] Further, the first DA bond forming monomer is one of furan, cyclopentadiene, and tetrahydrocyclopentadiene; the second DA bond forming monomer is one of maleimide, ethylenemaleimide, and bismaleimide. Preferably, the first DA bond forming monomer is 2,5-furan dimethanol, and the second DA bond forming monomer is bismaleimide.

[0020] Further, the catalyst is one or more of dibutyltin dilaurate, stannous octoate, and dibutyltin oxide. Preferably, the catalyst is dibutyltin dilaurate.

[0021] Further, the organic solvent is one or more of dimethylacetamide, dimethyl sulfoxide, toluene, dichloromethane, methyl ethyl ketone, and acetone. Preferably, the organic solvent is N,N-dimethylacetamide.

[0022] Furthermore, in step (1), the mechanical stirring speed is 90-200 RPM, and the stirring time is 10-120 min; in step (2), the mechanical stirring speed is 90-200 RPM, the reaction time is 60-180 min, and the reaction temperature is 80-100°C.

[0023] This setting controls the stirring speed, stirring time, and reaction time to ensure that the prepared self-healing polyurethane film has both high mechanical strength and self-healing efficiency. For example, the influence of stirring speed on film strength. When the stirring speed is too low (such as less than 90RPM), the raw materials are mixed unevenly, and local ratio imbalance occurs, thus affecting the uniformity and strength of the polyurethane film. Although the stirring speed is too high (such as more than 200RPM), it can improve the mixing uniformity of the raw materials to a certain extent, but it will cause excessive shearing, damage the polyurethane molecular chain, and also reduce the film strength.

[0024] Furthermore, in step (3), the reaction temperature is 30-90°C and the reaction time is 2-3h. Preferably, the reaction temperature is 50-80°C.

[0025] Furthermore, in step (2) and step (3), nitrogen is introduced during the reaction to ensure isolation from air.

[0026] Furthermore, in step (4), drying is performed in an oven for 24-48 hours, and the oven temperature is set at 60-80°C.

[0027] Furthermore, the thickness of the self-healing polyurethane film is 0.3-0.5 mm.

[0028] Furthermore, the relative humidity required for the storage condition of the self-repairing polyurethane film is less than 80%, preferably 40-50%.

[0029] A self-repairing polyurethane film containing disulfide bonds and DA bonds is obtained by adopting the above-mentioned preparation method.

[0030] Compared with the prior art, the self-healing polyurethane film containing disulfide bonds and DA bonds and the preparation method thereof described in the present invention have the following advantages:

[0031] 1) The present invention introduces dynamic disulfide bonds into polyurethane by prepolymerization and chain extension, reacting disulfide bonds with isocyanate groups, so that polyurethane has good self-healing properties, and then cross-linking reaction is carried out to introduce DA bonds, which can further fix the disulfide bonds in the cross-linked network formed by DA bonds and polyurethane. On the basis of improving the mechanical strength of the polyurethane film, the breaking and reconstruction of the disulfide bonds are more stable, thereby improving the self-healing efficiency of the polyurethane;

[0032] 2) By controlling the content of the dual dynamic bonds, the polyurethane film can achieve self-repair of scratches within 0.5 hours at a temperature of 80°C. At the same time, the tensile strength of the self-repairing polyurethane film can reach 31MPa, the elastic modulus can reach 20MPa, and the toughness can reach 96 MJ m-3. The excellent mechanical strength and good self-repairing properties make it suitable for use as a resin base material in the development of anti-corrosion coatings, which can reduce the number of repairs, save manpower and material resources, and extend the service life;

[0033] 3) The preparation method of the self-healing polyurethane film of the present invention is simple, does not require complex equipment, has mild reaction conditions, and can be promoted and used on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The stress-strain curves of the self-healing polyurethane films containing disulfide bonds and DA bonds prepared in Examples 1 to 3 of the present invention;

[0035] Figure 2 FTIR image of the self-healing polyurethane film containing disulfide bonds and DA bonds prepared in Example 1 of the present invention;

[0036] Figure 3 This is a graph showing the self-healing results of an incision at 80°C of the self-healing polyurethane film containing disulfide bonds and DA bonds prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0038] Example 1

[0039] (1) Add 50g of N,N-dimethylacetamide into a three-necked flask, dissolve 10g of polycaprolactone diol, 6g of isophorone diisocyanate, 3g of bis(4-hydroxyphenyl) disulfide, and 1.5g of 2,5-furan dimethanol in N,N-dimethylacetamide, add 0.6g of dibutyltin dilaurate to N,N-dimethylacetamide, and stir mechanically at a speed of 120 RPM for 2h to make the solution uniform;

[0040] (2) Nitrogen was introduced into the three-necked flask to exhaust all the air, and then the temperature was set to 80°C, with mechanical stirring at a speed of 120 RPM, and the reaction time was 3 h. Nitrogen was continuously introduced during the reaction;

[0041] (3) After the reaction in step (2) was completed, 1.9 g of bismaleimide was slowly dripped into the solution obtained after the reaction in step (2) in a nitrogen environment. After the dripping was completed, the system was reacted at 60° C. for 3 h.

[0042] (4) Pour the solution obtained after the reaction in step (3) into a polytetrafluoroethylene mold and dry it to obtain a self-healing polyurethane film. The drying temperature is 70° C. and the drying time is 36 hours.

[0043] Example 2

[0044] (1) Add 50g of N,N-dimethylacetamide into a three-necked flask, dissolve 10g of polycaprolactone diol, 5g of isophorone diisocyanate, 1.2g of bis(4-hydroxyphenyl) disulfide, and 1.3g of 2,5-furan dimethanol in N,N-dimethylacetamide, add 0.6g of dibutyltin dilaurate to N,N-dimethylacetamide, and stir mechanically at a speed of 150 RPM for 2h to make the solution uniform;

[0045] (2) Nitrogen was introduced into the three-necked flask to exhaust all the air, and then the temperature was set to 80°C, with mechanical stirring at a speed of 120 RPM, and the reaction time was 3 h. Nitrogen was continuously introduced during the reaction;

[0046] (3) After the reaction in step (2) was completed, 1.8 g of bismaleimide was slowly dripped into the solution obtained after the reaction in step (2) in a nitrogen environment. After the dripping was completed, the system was reacted at 60° C. for 3 h.

[0047] (4) Pour the solution obtained after the reaction in step (3) into a polytetrafluoroethylene mold and dry it to obtain a self-healing polyurethane film. The drying temperature is 60° C. and the drying time is 48 hours.

[0048] Example 3

[0049] (1) Add 50g of N,N-dimethylacetamide into a three-necked flask, dissolve 10g of polycaprolactone diol, 6g of isophorone diisocyanate, 2.6g of bis(4-hydroxyphenyl) disulfide, and 0.7g of 2,5-furan dimethanol in N,N-dimethylacetamide, add 0.6g of dibutyltin dilaurate to N,N-dimethylacetamide, and stir mechanically at a speed of 120 RPM for 2h to make the solution uniform;

[0050] (2) Nitrogen was introduced into the three-necked flask to exhaust all the air, and then the temperature was set to 80°C, with mechanical stirring at a speed of 120 RPM, and the reaction time was 3 h. Nitrogen was continuously introduced during the reaction;

[0051] (3) After the reaction in step (2) was completed, 0.9 g of bismaleimide was slowly dripped into the solution obtained after the reaction in step (2) in a nitrogen environment. After the dripping was completed, the system was reacted at 60° C. for 3 h.

[0052] (4) Pour the solution obtained after the reaction in step (3) into a polytetrafluoroethylene mold and dry it to obtain a self-healing polyurethane film. The drying temperature is 80° C. and the drying time is 24 hours.

[0053] Comparative Example 1

[0054] (1) Add 50g of N,N-dimethylacetamide into a three-necked flask, dissolve 10g of polycaprolactone diol, 5g of isophorone diisocyanate, and 2g of 2,5-furan dimethanol in N,N-dimethylacetamide, add 0.6g of dibutyltin dilaurate to N,N-dimethylacetamide, and stir mechanically at a speed of 200 RPM for 2 hours to make the solution uniform;

[0055] (2) Nitrogen was introduced into the three-necked flask to exhaust the air, and then the temperature was set to 80°C, with mechanical stirring at a speed of 200 RPM, and the reaction time was 3 h. Nitrogen was continuously introduced during the reaction;

[0056] (3) After the reaction in step (2) was completed, 3 g of bismaleimide was slowly added dropwise to the solution obtained after the reaction in step (2) in a nitrogen environment. After the addition was completed, the system was reacted at 60° C. for 3 h.

[0057] (4) Pour the solution obtained in step (3) into a polytetrafluoroethylene mold and dry it to obtain a self-healing polyurethane containing DA bonds.

[0058] Comparative Example 2

[0059] (1) Add 50g of N,N-dimethylacetamide into a three-necked flask, dissolve 10g of polycaprolactone diol, 6g of isophorone diisocyanate, and 5g of bis(4-hydroxyphenyl) disulfide in N,N-dimethylacetamide, add 0.6g of dibutyltin dilaurate to N,N-dimethylacetamide, and stir mechanically at a speed of 90 RPM for 2h to make the solution uniform;

[0060] (2) Nitrogen was introduced into the three-necked flask to exhaust all air, and then the temperature was set to 90°C, and the mechanical stirring was performed at a speed of 90 RPM. The reaction time was 3 h, and nitrogen was continuously introduced during the reaction;

[0061] (3) Pour the solution obtained after the reaction in step (2) into a polytetrafluoroethylene mold and dry it to obtain a self-healing polyurethane material containing disulfide bonds. The drying temperature is 80° C. and the drying time is 24 hours.

[0062] Performance Testing

[0063] (1) The tensile strength of the self-healing polyurethane film in Examples 1-3 and Comparative Examples 1-2 was tested according to GB / T 1040.1-2006. The test results are shown in Table 1 below.

[0064] (2) Examples 1-3 and Comparative Examples 1-2 tested the repair efficiency of the self-healing polyurethane film, and the repair efficiency was: repair rate = T' / Tx100%; wherein T' is the tensile strength of the sample after self-healing treatment, and T is the initial tensile strength of the sample, in MPa; the repair method is to heat the cut sample in an oven at a temperature of 80°C for 0.5h.

[0065] (3) The stress response curves of Examples 1 to 3 are shown in Figure 1 The mechanical property test standards and test results of the film in Example 1 are shown in Table 2 below.

[0066] Table 1

[0067] project Tensile strength (MPa) 80℃ self-repair efficiency (%) Example 1 31 83 Example 2 42 26 Example 3 8 90 Comparative Example 1 43 0 Comparative Example 2 2 97

[0068] It can be concluded from Table 1 that the self-repairing polyurethane film containing disulfide bonds and DA bonds prepared by prepolymerization and chain extension and then cross-linking reaction has a significantly improved tensile strength compared to the self-repairing polyurethane film containing only disulfide bonds, and a significantly improved repair efficiency compared to the self-repairing polyurethane film containing only DA bonds. Moreover, according to Table 1 and Figure 1 It was found that when the molar ratio of 2,5-furan dimethanol:bis(4-hydroxyphenyl) disulfide was 1:1, the self-healing polyurethane film achieved good performance in both tensile strength and self-healing efficiency. The tensile strength of the self-healing polyurethane film was 31 MPa and the repair rate was 83%.

[0069] Table 2

[0070] project performance Test Standards Tensile Strength 31MPa GB / T 1040.1-2006 toughness <![CDATA[96MJ m -3 ]]> GB / T 1040.1-2006 Elastic modulus 20MPa GB / T 1040.1-2006

[0071] Table 2 shows the mechanical properties test of the self-healing polyurethane film of Example 1 of the present invention. The tensile strength of the film is 31 MPa. Figure 1 The elastic modulus and toughness calculated from the stress-strain curve are 20 MPa and 96 MJ m -3 , it can be seen that the self-healing polyurethane film of the present invention has high mechanical strength and toughness.

[0072] Figure 2 This is the FTIR image of the self-healing polyurethane film containing disulfide bonds and DA bonds prepared in Example 1. From the FTIR spectrum, it can be seen that the 2270 cm -1 The -NCO absorption peak at 1720 cm-1 disappeared, indicating that all isocyanate groups had reacted completely. -1The absorption peak at 3359 cm represents the carbonyl group (C=O) of the amide in the polyurethane, while the absorption peak at 3359 cm -1 The absorption peak at 1770 cm -1 The characteristic absorption peak of DA bond appears at .

[0073] Figure 3 The self-healing result of the self-healing polyurethane film containing disulfide bonds and DA bonds prepared in Example 1 at 80°C (the left side is not heated for 0h, and the right side is heated for 0.5h); Figure 3 It can be seen that when the temperature is 80°C, the sample can be heated in an oven for 0.5h to complete the incision self-repair through the dynamic exchange of disulfide bonds.

[0074] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for preparing a self-repairing polyurethane film containing disulfide bonds and DA bonds, characterized in that: The steps include: (1) Add an organic solvent into a three-necked flask, then dissolve the diol, diisocyanate, disulfide bond monomer, and DA bond forming monomer in the organic solvent, then add the catalyst and stir mechanically to mix evenly; (2) nitrogen was introduced into the three-necked flask to exhaust the air, the reaction temperature was set, and the reaction was carried out under mechanical stirring; (3) Under nitrogen environment, add two drops of DA bond forming monomer to the solution obtained after the reaction in step (2). After the addition of the two drops of DA bond forming monomer is completed, set the reaction temperature and react for a period of time; (4) Pour the solution obtained after the reaction in step (3) into a polytetrafluoroethylene mold and dry it to obtain a self-healing polyurethane film.

2. The preparation method according to claim 1, characterized in that: The weight ratio of the diol, diisocyanate, disulfide bond monomer, organic solvent, catalyst, DA bond forming monomer one, and DA bond forming monomer two is (1-40): (1-40): (20-60): (0.1-1): (1-40): (1:40).

3. The preparation method according to claim 1, characterized in that: The molar ratio of the disulfide bond monomer to the DA bond forming monomer is 1:(0.5-2.5).

4. The preparation method according to claim 1, characterized in that: The molar ratio of the disulfide bond monomer to the DA bond forming monomer is 1:

1.

5. The preparation method according to claim 1, characterized in that: The disulfide bond monomer is one or more of dialkyl disulfide, dihydroxytoluene disulfide, and bis(4-hydroxyphenyl) disulfide.

6. The preparation method according to claim 1, characterized in that: The first DA bond forming monomer is one of furan, cyclopentadiene and tetrahydrocyclopentadiene; the second DA bond forming monomer is one of maleimide, ethylenemaleimide and bismaleimide.

7. The preparation method according to claim 1, characterized in that: The catalyst is one or more of dibutyltin dilaurate, stannous octoate, and dibutyltin oxide.

8. The preparation method according to claim 1, characterized in that: The organic solvent is one or more of dimethylacetamide, dimethyl sulfoxide, toluene, dichloromethane, methyl ethyl ketone and acetone.

9. The preparation method according to claim 1, characterized in that: In step (3), the reaction temperature is 30-90°C and the reaction time is 2-3h.

10. A self-repairing polyurethane film containing disulfide bonds and DA bonds, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 9.

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