Chain extender, preparation method and application thereof, and polyurethane and preparation method thereof

Abstract

The application belongs to the technical field of polyurethane, and particularly relates to a chain extender, a preparation method and application thereof, and polyurethane and a preparation method thereof. The chain extender provided by the application has the structure shown in formula 1: the chain extender provided by the application contains two kinds of dynamic covalent bonds (S=S and C=N), and the rigid unit benzene ring contained in the chain extender can improve the strength of the material, and the long-chain structure can also impart the material with stretchability. The polyurethane prepared by using the chain extender provided by the application contains polyol soft segments and chain extender hard segments at the same time, so that the polyurethane has shape memory performance.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane technology, specifically relating to a chain extender, its preparation method and application, and polyurethane and its preparation method. Background Technology

[0002] Polyurethane materials have wide applications in numerous fields due to their wide availability of raw materials and strong structural designability. In polyurethane synthesis, chain extenders play a crucial role in lengthening molecular chains, increasing molecular weight, and improving the material's mechanical properties. However, traditional polyol or polyamine-based small-molecule chain extenders often only provide basic chain-extending functions and are unlikely to introduce additional functionalities into polyurethane materials, such as improving mechanical properties or enhancing shape memory characteristics. These limitations restrict further improvements in the performance and multifunctional development of polyurethane materials. Summary of the Invention

[0003] In view of this, the present invention provides a chain extender and its preparation method and application, as well as polyurethane and its preparation method. The polyurethane prepared with the chain extender provided by the present invention has high mechanical strength and shape memory properties.

[0004] To solve the above-mentioned technical problems, the present invention provides a chain extender having the structure shown in Formula 1:

[0005]

[0006] This invention also provides a method for preparing the chain extender described in the above technical solution, comprising the following steps:

[0007] The chain extender is obtained by mixing vanillin, 4,4-dithiodiphenylamine and a first organic solvent, subjecting the mixture to a Schiff base reaction, and then crystallizing the mixture.

[0008] Preferably, the Schiff base reaction is carried out at a temperature of 60–80°C for 5–8 hours.

[0009] Preferably, the crystallization is evaporation crystallization, and the evaporation crystallization temperature is 60-80℃, and the time is 12-24h.

[0010] Preferably, the first organic solvent includes anhydrous ethanol or N,N-dimethylformamide;

[0011] The molar ratio of vanillin to 4,4-dithiodiphenylamine is 2:0.8 to 1.2.

[0012] The present invention also provides the application of the chain extender described in the above technical solution or the chain extender prepared by the preparation method described in the above technical solution in the preparation of polyurethane.

[0013] The present invention also provides a polyurethane having the structure shown in Formula 2:

[0014]

[0015] Where n is 21-30, for

[0016] The present invention also provides a method for preparing the polyurethane described in the above technical solution, comprising the following steps:

[0017] Polycaprolactone diol, hexamethylene diisocyanate, catalyst, and second organic solvent were mixed and subjected to a first nucleophilic addition reaction to obtain a prepolymer.

[0018] The prepolymer and chain extender solution are mixed and subjected to a second nucleophilic addition reaction before molding to obtain the polyurethane; the chain extender is the chain extender described in the above technical solution or the chain extender prepared by the preparation method described in the above technical solution.

[0019] Preferably, the catalyst is dibutyltin dilaurate;

[0020] The second organic solvent includes N,N-dimethylformamide, ethyl acetate, or N-methylpyrrolidone;

[0021] The molar ratio of hexamethylene diisocyanate to polycaprolactone diol is 1.5 to 3:1;

[0022] The molar ratio of polycaprolactone diol to chain extender is 1:0.5 to 2.

[0023] Preferably, the temperatures of the first nucleophilic addition reaction and the second affinity addition reaction are independently 58–62 °C, and the times of the first nucleophilic addition reaction and the second affinity addition reaction are independently 2.5–3.5 h.

[0024] This invention provides a chain extender having the structure shown in Formula 1: The chain extender provided by this invention contains two types of dynamic covalent bonds (S=S and C=N), and the rigid benzene ring in the chain extender can improve the strength of the material, while the long chain structure can also impart stretchability to the material. Polyurethane prepared using the chain extender provided by this invention contains both soft polyol segments and hard chain extender segments, thereby giving the polyurethane shape memory properties. Attached Figure Description

[0025] Figure 1 The 1H NMR spectrum of the chain extender prepared in Example 1;

[0026] Figure 2 The infrared spectra of vanillin, 4,4'-dithiodiphenyl and the prepared chain extender in Example 1 are shown.

[0027] Figure 3 Tensile curves of the polyurethanes prepared in Examples 2-4 and Comparative Example 1 are shown.

[0028] Figure 4 This is a diagram illustrating the shape memory process of the polyurethane material prepared in Example 3. Detailed Implementation

[0029] This invention provides a chain extender having the structure shown in Formula 1:

[0030]

[0031] The chain extender provided by this invention introduces a rigid benzene ring and a hydroxyl group that can form hydrogen bonds, which can improve the tensile properties and shape memory function of polyurethane.

[0032] This invention also provides a method for preparing the chain extender described in the above technical solution, comprising the following steps:

[0033] The chain extender is obtained by mixing vanillin, 4,4-dithiodiphenylamine and a first organic solvent, subjecting the mixture to a Schiff base reaction, and then crystallizing the mixture.

[0034] In this invention, the mixing preferably includes the following steps:

[0035] Vanillin is dissolved in a first organic solvent to obtain a vanillin solution;

[0036] The vanillin solution and 4,4-dithiodiphenylamine are first mixed.

[0037] This invention dissolves vanillin in a first organic solvent to obtain a vanillin solution. In this invention, the first organic solvent preferably includes anhydrous ethanol or N,N-dimethylformamide, more preferably anhydrous ethanol. In this invention, the molar concentration of the vanillin solution is preferably 0.25–0.30 mol / L, more preferably 0.29 mol / L. In this invention, the dissolution is preferably carried out under stirring. This invention does not have special requirements for the stirring, as long as complete dissolution is achieved.

[0038] After obtaining the vanillin solution, the present invention first mixes the vanillin solution with 4,4-dithiodiphenylamine. In the present invention, the molar ratio of vanillin to 4,4-dithiodiphenylamine is preferably 2:0.8 to 1.2, more preferably 2:1. The present invention has no special requirements for the first mixing, as long as it can be mixed evenly.

[0039] In this invention, the temperature of the Schiff base reaction is preferably 60-80°C, more preferably 65-70°C; the time of the Schiff base reaction is preferably 5-8 hours, more preferably 6-7 hours.

[0040] In this invention, the equation for the Schiff base reaction is shown in equation a:

[0041]

[0042] In this invention, the crystallization is preferably evaporation crystallization, and the evaporation crystallization temperature is preferably 60-80°C, more preferably 70-75°C; the evaporation crystallization time is preferably 12-24 hours, more preferably 18-20 hours. In this invention, the evaporation crystallization is preferably carried out in an oven.

[0043] In this invention, the chain extender is preferably an orange-red crystal, denoted as HMADI.

[0044] This invention also provides the application of the chain extender described in the above-described technical solutions or the chain extender prepared by the preparation method described in the above-described technical solutions in the preparation of polyurethane. Polyurethane prepared using the chain extender provided by this invention exhibits high tensile strength and good shape memory properties.

[0045] The present invention also provides a polyurethane having the structure shown in Formula 2:

[0046]

[0047] Wherein, n is 21 to 30, preferably 25; m is the degree of polymerization of polyurethane. for

[0048] The present invention also provides a method for preparing the polyurethane described in the above technical solution, comprising the following steps:

[0049] Polycaprolactone diol, hexamethylene diisocyanate, catalyst, and second organic solvent were mixed and subjected to a first nucleophilic addition reaction to obtain a prepolymer.

[0050] The prepolymer and chain extender solution are mixed and subjected to a second nucleophilic addition reaction, followed by molding to obtain the polyurethane; the chain extender is the chain extender described in the above technical solution or the chain extender prepared by the preparation method described in the above technical solution.

[0051] The present invention involves mixing polycaprolactone diol, hexamethylene diisocyanate, a catalyst, and a second organic solvent to carry out a first nucleophilic addition reaction to obtain a prepolymer.

[0052] In this invention, the mixing preferably includes the following steps:

[0053] Polycaprolactone diol is dissolved in a second organic solvent to obtain a polycaprolactone diol solution;

[0054] The catalyst was added dropwise to the polycaprolactone diol solution after hexamethylene diisocyanate was added.

[0055] This invention dissolves polycaprolactone diol in a second organic solvent to obtain a polycaprolactone diol solution. Preferably, the dissolution process further includes drying the polycaprolactone diol. The drying temperature is preferably 110–120°C, more preferably 110–115°C; the drying time is preferably 3–6 hours, more preferably 4–5 hours. The relative molecular mass of the polycaprolactone diol is preferably 2500–3500, more preferably 3000. The second organic solvent preferably includes N,N-dimethylformamide, ethyl acetate, or N-methylpyrrolidone, more preferably N,N-dimethylformamide. The molar concentration of the polycaprolactone diol solution is preferably 0.04–0.07 mol / L, more preferably 0.625 mol / L. This invention does not have special requirements for the dissolution process, as long as complete dissolution is achieved.

[0056] After obtaining a polycaprolactone diol solution, the present invention adds hexamethylene diisocyanate dropwise to the polycaprolactone diol solution followed by a catalyst. In the present invention, the catalyst is preferably dibutyltin dilaurate. In the present invention, the catalyst is preferably added dropwise, and the amount of dibutyltin dilaurate added is preferably 4-6 drops, more preferably 5 drops. In the present invention, stirring is preferably performed during the catalyst dropwise addition process. The present invention has no special requirements for the stirring, as long as the mixture is homogeneous.

[0057] In this invention, the molar ratio of hexamethylene diisocyanate to polycaprolactone diol is preferably 1.5–3:1, more preferably 2–2.5:1. This invention does not have any particular limitation on the addition of hexamethylene diisocyanate; it can be added dropwise.

[0058] In this invention, the temperature of the first nucleophilic addition reaction is preferably 58-62°C, more preferably 60°C; the time of the first nucleophilic addition reaction is preferably 2.5-3.5 h, more preferably 3 h.

[0059] After obtaining the prepolymer, the present invention mixes the prepolymer and a chain extender solution and performs a second nucleophilic addition reaction to form the polyurethane. In the present invention, the preparation method of the chain extender solution preferably includes the following steps: dissolving the chain extender in a third organic solvent to obtain the chain extender solution. In the present invention, the third organic solvent preferably includes N,N-dimethylformamide, ethyl acetate, or N-methylpyrrolidone, more preferably N,N-dimethylformamide. In the present invention, the molar concentration of the chain extender solution is preferably 0.1–0.2 mol / L, more preferably 0.125 mol / L.

[0060] In this invention, the molar ratio of polycaprolactone diol to chain extender is preferably 1:0.5 to 2, more preferably 1:1 to 1.5.

[0061] The present invention has no special requirements for the mixing, as long as the mixing is uniform.

[0062] In this invention, the temperature of the second nucleophilic addition reaction is preferably 58-62°C, more preferably 60°C; the time of the second nucleophilic addition reaction is preferably 2.5-3.5 h, more preferably 3 h.

[0063] In this invention, the molding process preferably involves evaporating the system after the second nucleophilic addition reaction to remove the solvent; the evaporation temperature is preferably 75–85°C, more preferably 80°C. This invention does not have a specific limitation on the evaporation time, as long as the solvent is removed before material molding. In this invention, the molding process preferably involves placing the system after the second nucleophilic addition reaction in a mold.

[0064] In this invention, the equations for the first nucleophilic addition reaction and the second nucleophilic addition reaction are shown in equation b:

[0065]

[0066] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0067] Example 1

[0068] 3g (0.02mol) of vanillin was dissolved in 70mL of anhydrous ethanol under stirring to obtain a vanillin solution with a molar concentration of 0.29mol / L.

[0069] A vanillin solution and 2.5 g (0.01 mol) of 4,4'-dithiodiphenyl were mixed and subjected to a Schiff base reaction at 70 °C for 6 h. The mixture was then placed in an oven and evaporated and crystallized at 70 °C for 18 h to obtain an orange-red crystalline chain extender, which was named HMADI.

[0070] Example 2

[0071] Polycaprolactone diol with a relative molecular mass of 3000 was dried at 115℃ for 5 h; 7.5 g (0.0025 mol) of the dried polycaprolactone diol was dissolved in 40 mL of N,N-dimethylformamide to obtain a polycaprolactone diol solution with a molar concentration of 0.0625 mol / L.

[0072] Add 0.6 mL (0.00375 mol) of hexamethylene diisocyanate dropwise to a polycaprolactone diol solution, followed by the addition of 4 drops of dibutyltin dilaurate (with stirring). Initiate the first nucleophilic addition reaction at 60 °C for 3 h to obtain the prepolymer.

[0073] 0.65 g (0.00125 mol) of the chain extender HMADI prepared in Example 1 was dissolved in 10 mL of N,N-dimethylformamide to obtain a chain extender solution with a molar concentration of 0.125 mol / L; the chain extender solution and the prepolymer were mixed and subjected to a second nucleophilic addition reaction at 60 °C for 3 h; the system after the second nucleophilic addition reaction was placed in a mold and evaporated at 80 °C to obtain polyurethane.

[0074] Example 3

[0075] Polycaprolactone diol with a relative molecular mass of 3000 was dried at 115℃ for 5 h; 7.5 g (0.0025 mol) of the dried polycaprolactone diol was dissolved in 40 mL of N,N-dimethylformamide to obtain a polycaprolactone diol solution with a molar concentration of 0.0625 mol / L.

[0076] Add 0.8 mL (0.005 mol) of hexamethylene diisocyanate dropwise to a polycaprolactone diol solution, followed by the addition of 5 drops of dibutyltin dilaurate (with stirring). Initiate the first nucleophilic addition reaction at 60 °C for 3 h to obtain the prepolymer.

[0077] 1.3 g (0.0025 mol) of the chain extender HMADI prepared in Example 1 was dissolved in 20 mL of N,N-dimethylformamide to obtain a chain extender solution with a molar concentration of 0.125 mol / L; the chain extender solution and the prepolymer were mixed and subjected to a second nucleophilic addition reaction at 60 °C for 3 h; the system after the second nucleophilic addition reaction was placed in a mold and evaporated at 80 °C to obtain polyurethane.

[0078] Example 4

[0079] Polycaprolactone diol with a relative molecular mass of 3000 was dried at 115℃ for 5 h; 7.5 g (0.0025 mol) of the dried polycaprolactone diol was dissolved in 40 mL of N,N-dimethylformamide to obtain a polycaprolactone diol solution with a molar concentration of 0.0625 mol / L.

[0080] 1.2 mL (0.0075 mol) of hexamethylene diisocyanate was added dropwise to a polycaprolactone diol solution, followed by the addition of 5 drops of dibutyltin dilaurate (with stirring). The first nucleophilic addition reaction was carried out at 60 °C for 3 h to obtain the prepolymer.

[0081] 2.6 g (0.005 mol) of the chain extender HMADI prepared in Example 1 was dissolved in 40 mL of N,N-dimethylformamide to obtain a chain extender solution with a molar concentration of 0.125 mol / L; the chain extender solution and the prepolymer were mixed and subjected to a second nucleophilic addition reaction at 60 °C for 3 h; the system after the second nucleophilic addition reaction was placed in a mold and evaporated at 80 °C to obtain polyurethane.

[0082] Comparative Example 1

[0083] Polycaprolactone diol with a relative molecular mass of 3000 was dried at 115℃ for 5 h; 7.5 g (0.0025 mol) of the dried polycaprolactone diol was dissolved in 40 mL of N,N-dimethylformamide to obtain a polycaprolactone diol solution with a molar concentration of 0.0625 mol / L.

[0084] Add 0.8 mL (0.005 mol) of hexamethylene diisocyanate dropwise to a polycaprolactone diol solution, followed by the addition of 5 drops of dibutyltin dilaurate (with stirring). Initiate the first nucleophilic addition reaction at 60 °C for 3 h to obtain the prepolymer.

[0085] 0.62 g (0.0025 mol) of 4,4'-dithiodiphenylamine was dissolved in 20 mL of N,N-dimethylformamide to obtain a chain extender solution with a molar concentration of 0.125 mol / L. The chain extender solution and the prepolymer were mixed and subjected to a second nucleophilic addition reaction at 60 °C for 3 h. The system after the second nucleophilic addition reaction was placed in a mold and evaporated at 80 °C to obtain polyurethane.

[0086] The chain extender prepared in Example 1 was subjected to 1H NMR spectroscopy, and the resulting spectrum is shown below. Figure 1 As shown. By Figure 1 The hydrogen nuclear magnetic resonance (NMR) spectrum of the synthesized polyurethane chain extender revealed hydrogen chemical shifts of 9.78 (s, 1H), 8.45 (s, 1H), 7.54 (s, 2H), 7.32 (d, 1H), 7.28 (d, 1H), 7.25 (s, 2H), 6.90 (s, 1H), and 3.84 (s, 3H). These chemical shifts and the area under the integral of the curves are consistent with the chemical structure of the target product.

[0087] Infrared spectroscopy was performed on vanillin, 4,4'-dithiodiphenyl, and the prepared chain extender in Example 1, and the infrared spectra were obtained, as shown below. Figure 2 As shown. By Figure 2 It can be observed that the aldehyde group of vanillin undergoes an aldehyde-amine condensation reaction with the amino group of 4,4-dithiodiphenylamine to form an imine bond (-C=N-), as shown in the figure at 1598 cm⁻¹. -1 The characteristic peak at 3370 cm⁻¹ is the characteristic peak of -C = N⁻. -1The peak at 1283 cm⁻¹ represents the stretching vibration of the hydroxyl group. -1 The peak at 1387 cm⁻¹ is a characteristic peak of COC. -1 The position represents the bending vibration of the methyl group. This demonstrates the chain extender prepared in Example 1 that has the structure shown in Formula 1.

[0088] Tensile tests were conducted on the polyurethanes prepared in Examples 2-4 and Comparative Example 1 using an electronic universal tensile testing machine according to ISO 527-2 / 1BB at room temperature and a tensile rate of 10 mm / min. The tensile curves are shown below. Figure 3 As shown, the obtained stress and strain values ​​are listed in Table 1.

[0089] Table 1. Tensile properties of polyurethanes prepared in Examples 2-4 and Comparative Example 1

[0090] Example 2 29.81 1166.10 Example 3 36.00 1198.00 Example 4 15.15 733.09 Comparative Example 1 26.85 969.88

[0091] Combining Table 1 and Figure 3 It can be seen that, compared with the comparative example, the chain extender provided by the present invention has the effect of improving the stress and strain of the material.

[0092] The polyurethane prepared in Example 3 was used as the test object. A small section of the material was cut and bent at 30°C, then placed in an environment at -40°C and left to stand for 1 minute. The temporary shape of the material was fixed. The material was then taken out of the low temperature environment and placed in an environment at 30°C. The material gradually returned to a flat shape from the bent shape. Figure 4 For the shape memory process of polyurethane materials, Figure 4 In the diagram, 'a' represents the initial shape of the material, 'b' represents the temporary shape fixed at -40℃, and 'c, d, and e' represent the process by which the material gradually returns to its original shape at 30℃. Figure 4 It can be seen that the polyurethane prepared by this invention has shape memory function.

[0093] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A polyurethane, characterized in that, It has the structure shown in Equation 2: Formula 2; Where n is between 21 and 30, for ; The method for preparing the polyurethane includes the following steps: Polycaprolactone diol, hexamethylene diisocyanate, catalyst, and a second organic solvent are mixed and subjected to a first nucleophilic addition reaction to obtain a prepolymer; the molar ratio of hexamethylene diisocyanate to polycaprolactone diol is 2:

1. The prepolymer and chain extender solution are mixed, and after undergoing a second nucleophilic addition reaction, the mixture is molded to obtain the polyurethane; the molar ratio of polycaprolactone diol to chain extender is 1:

1. The preparation method of the chain extender includes the following steps: The chain extender is obtained by mixing vanillin, 4,4-dithiodiphenylamine and a first organic solvent and then performing a Schiff base reaction; the crystallization is evaporation crystallization, and the evaporation crystallization temperature is 60~80℃ and the time is 12~24h.

2. The polyurethane according to claim 1, characterized in that, The Schiff base reaction is carried out at a temperature of 60-80°C for 5-8 hours.

3. The polyurethane according to claim 1, characterized in that, The first organic solvent includes anhydrous ethanol or N,N-dimethylformamide; The molar ratio of vanillin to 4,4-dithiodiphenylamine is 2:0.8~1.

2.

4. The method for preparing polyurethane according to any one of claims 1 to 3, characterized in that, Includes the following steps: Polycaprolactone diol, hexamethylene diisocyanate, catalyst, and a second organic solvent are mixed and subjected to a first nucleophilic addition reaction to obtain a prepolymer; the molar ratio of hexamethylene diisocyanate to polycaprolactone diol is 2:

1. The prepolymer and chain extender solution are mixed, and after undergoing a second nucleophilic addition reaction, the mixture is molded to obtain the polyurethane; the molar ratio of polycaprolactone diol to chain extender is 1:

1. The preparation method of the chain extender includes the following steps: The chain extender is obtained by mixing vanillin, 4,4-dithiodiphenylamine and a first organic solvent and then performing a Schiff base reaction; the crystallization is evaporation crystallization, and the evaporation crystallization temperature is 60~80℃ and the time is 12~24h.

5. The preparation method according to claim 4, characterized in that, The catalyst is dibutyltin dilaurate; The second organic solvent includes N,N-dimethylformamide, ethyl acetate, or N-methylpyrrolidone.

6. The preparation method according to claim 4, characterized in that, The temperatures for the first and second nucleophilic addition reactions are independently 58~62℃, and the time for the first and second nucleophilic addition reactions is independently 2.5~3.5h.

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