Polyurethane elastomer material with multi-stimulus response discoloration, high mechanical strength and self-healing characteristics

Abstract

The invention discloses a polyurethane elastomer material with multi-stimulus response discoloration, high mechanical strength and self-healing characteristics as well as a preparation method and application thereof, in the structural formula of the polyurethane elastomer material, A is selected from substituted or unsubstituted phenyl, biphenyl, xylyl, naphthyl, cyclohexyl, butyl and hexyl, and B is selected from substituted or unsubstituted phenyl, biphenyl, xylyl, naphthyl, cyclohexyl, butyl and hexyl; the substituent groups are alkyl groups, alkoxy groups and halogen methyl groups of C4-C6; and B is polyether polyol. W is a positive integer ranging from 10 to 80, x is a positive integer ranging from 4 to 8, y is a positive integer ranging from 20 to 70, and z is a positive integer ranging from 20 to 90. According to the invention, adipic acid dihydrazide, 2, 2-bis (hydroxymethyl) propionic acid and rhodamine 6G ethylene glycol are used as chain extenders, and organic tin is used for catalytic polymerization to form the organic tin-based polymer. The material disclosed by the invention has the characteristic of color change response to external stress, ultraviolet irradiation and an acid environment, can be subjected to shape programming after being heated, and also has excellent mechanical strength and self-healing performance.

Description

Technical Field

[0001] The invention relates to a polyurethane elastomer material with multi-stimulus response color change, high mechanical strength and self-healing properties, as well as a preparation method and application thereof, belonging to the field of new material technology. Background Art

[0002] Stimulus-responsive color-changing materials have the ability to sense environmental changes and respond, showing broad application prospects in medical monitoring, smart packaging, adaptive camouflage and other fields. Through sophisticated design at the molecular level, this type of material can convert external stimuli such as light, heat, force, and chemicals into visual color changes. However, most current materials only respond to a single stimulus after the introduction of a color-changing unit. To achieve multiple stimulus responses, different functional groups need to be introduced. It is worth noting that the integration of multiple stimulus responses does not mean simply superimposing multiple color-changing groups. On the contrary, it may be counterproductive and affect the original performance of the material. In addition, in actual applications, these materials often have defects such as poor mechanical properties and difficulty in self-healing after damage, resulting in their short lifespan and easy aging. Therefore, the development of materials that can produce color-changing reactions to multiple stimuli and have both high strength and self-healing capabilities is of great research significance.

[0003] The structure of polyurethane materials is usually composed of incompatible hard segments and soft segments, forming a unique microphase separation structure, which provides an ideal platform for multifunctional integration. The soft segment is generally composed of polyether or polyester polyols, which has high molecular chain fluidity, which helps to improve the stretchability and flexibility of the material. The hard segment contains rigid and polar groups, such as carbamate or urea groups, which form a cross-linked network through non-covalent hydrogen bonds inside and outside the polymer chain, which not only enhances the mechanical properties of the material, but also improves the self-healing efficiency. In addition, by adjusting parameters such as monomer type, addition ratio and reaction conditions, smart polyurethane materials with specific functions can be customized. At present, there is an urgent need to develop a simple and efficient preparation method to synthesize polyurethane elastomer materials with multiple stimulus-responsive color changes, high mechanical strength and self-healing properties, so as to meet their needs in practical applications. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a polyurethane elastomer material with multi-stimulus responsive color change, high mechanical strength and self-healing properties and a preparation method thereof, so as to cope with the application of the material in stimulus-responsive color change packaging, information anti-counterfeiting encryption, and environmental monitoring.

[0005] The implementation process of the present invention is as follows: A polyurethane elastomer material with multi-stimulus responsive color change, high mechanical strength and self-healing properties, the structural formula of which is:

[0006] Wherein, A is selected from substituted or unsubstituted phenyl, biphenyl, xylyl, naphthyl, cyclohexyl, butanyl and hexyl, and the substituent is C4-C6 alkyl, alkoxy, or halogen methyl; B is a polyether polyol; w is a positive integer of 10-80, x is a positive integer of 4-8, y is a positive integer of 20-70, and z is a positive integer of 20-90.

[0007] Furthermore, the polyether polyol is selected from at least one of polyethylene glycol 400-2000, polytetrahydrofuran 1000-2000, and polycaprolactone 1000-2000.

[0008] A method for preparing a polyurethane elastomer material having multi-stimulus responsive color change, high mechanical strength, and self-healing properties, the method comprising the following steps: reacting diisocyanate and polyether polyol under the action of an organic tin catalyst to obtain a prepolymer; The diisocyanate structural formula is OCN-A-NCO, where A is selected from substituted or unsubstituted phenyl, biphenyl, xylyl, naphthyl, cyclohexyl, butane and hexane, and the substituent is C4-C6 alkyl, alkoxy or halogen methyl; reacting the prepolymer with adipic acid dihydrazide to obtain a chain-extended polymer; (3) reacting the chain-extended polymer with rhodamine 6G ethylene glycol to obtain a copolymerized color-changing molecule polymer; (4) reacting the copolymerized color-changing molecule polymer with 2,2-bis(hydroxymethyl)propionic acid to obtain a crude material product; (5) Methanol is added to the crude material to remove unreacted isocyanate to obtain a polyurethane elastomer material.

[0009] In the above step (1), the structural formula of the diisocyanate is preferably:

[0010] In the above step (1), the organic tin catalyst is selected from at least one of dibutyltin dineoctanoate, dimethyltin dineoctanoate, methyltin mercaptan, dibutyltin dilaurate, and di-n-octyltin dilaurate.

[0011] In the above step (1), the molar ratio of diisocyanate to polyether polyol is 4:(1-4), and the reaction temperature is 30-100°C;

[0012] In the above step (2), the molar ratio of diisocyanate to adipic acid dihydrazide is 8:(1-8), and the reaction temperature is 30-100°C.

[0013] In the above step (3), the molar ratio of diisocyanate to rhodamine 6G glycol is 18:(1-2), and the reaction temperature is 30-100°C.

[0014] In the above step (4), the molar ratio of diisocyanate to 2,2-bis(hydroxymethyl)propionic acid is 8:(1-8), and the reaction temperature is 30-100°C.

[0015] The above-mentioned polyurethane elastomer material with multi-stimulus responsive color change, high mechanical strength and self-healing properties is used in stimulus-responsive color change packaging, information anti-counterfeiting encryption, environmental monitoring and other aspects.

[0016] Compared with existing technologies, this invention imparts multiple stimulus-responsive color-changing properties by covalently linking the stimuli-responsive color-changing molecule Rhodamine 6G glycol to a polyurethane material. Under applied stress, UV light irradiation, and acidic conditions, the material changes color from colorless to pink, demonstrating excellent color-changing responsiveness. By adjusting the ratio of the chain extender—adipic acid dihydrazide—to 2,2-bis(hydroxymethyl)propionic acid, the distribution of strong and weak hydrogen bonds between the amidourea and carboxylic acid is altered, thereby simultaneously improving mechanical properties and self-healing efficiency. This design offers broad application prospects for the material in a variety of fields, including stimuli-responsive color-changing packaging, information anti-counterfeiting and encryption, and environmental monitoring. Furthermore, the preparation process employed in this invention is simple and efficient, and the resulting material exhibits uniform structure and high reproducibility, demonstrating excellent practicality and promotional value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the infrared spectrum of the polyurethane elastomer material prepared in Example 1; Figure 2 This is a photograph of the color change of the polyurethane elastomer material prepared in Example 1 after applying tensile stress; Figure 3 This is a photograph of the color change of the polyurethane elastomer material prepared in Example 1 after being excited by a 365 nm ultraviolet lamp; Figure 4 This is a photograph showing the color change of the polyurethane elastomer material prepared in Example 1 after being immersed in 1 M hydrochloric acid; Figure 5 The stress-strain curves of the polyurethane elastomer material prepared in Example 1 before and after healing; Figure 6 These are optical microscope photos of the polyurethane elastomer material prepared in Example 1 before and after healing. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not intended to limit the present invention. The raw materials or auxiliary agents used in the embodiments of the present invention can be purchased or homemade.

[0019] The present invention provides a method for preparing a polyurethane elastomer material having multi-stimulus responsive color change, high mechanical strength, self-healing and shape memory properties, the method comprising the following steps:

[0020] (1) reacting diisocyanate and polyether polyol in the presence of an organic tin catalyst to obtain prepolymer I; wherein the molar ratio of diisocyanate to polyether polyol is 4:(1-4), and the reaction temperature is 30-100°C; The diisocyanate structural formula is OCN-A-NCO, where A is selected from substituted or unsubstituted phenyl, biphenyl, xylyl, naphthyl, cyclohexyl, butane and hexane, and the substituent is C4-C6 alkyl, alkoxy or halogen methyl.

[0021]

[0022] (2) reacting the prepolymer I with adipic acid dihydrazide to obtain a chain-extended polymer II; wherein the molar ratio of diisocyanate to adipic acid dihydrazide is 8:(1-8), and the reaction temperature is 30-100°C.

[0023]

[0024] (3) reacting the polymer II of the copolymerized phosphorescent molecule with rhodamine 6G glycol to obtain the polymer III of the copolymerized color-changing molecule; wherein the molar ratio of diisocyanate to rhodamine 6G glycol is 18:(1-2), and the reaction temperature is 30-100°C.

[0025]

[0026] (4) reacting the copolymerized color-changing molecule polymer III with 2,2-bis(hydroxymethyl)propionic acid to obtain a crude material product IV; wherein the molar ratio of diisocyanate to 2,2-bis(hydroxymethyl)propionic acid is 8:(1-8), and the reaction temperature is 30-100°C.

[0027]

[0028] (5) Methanol is added to the crude product IV to remove unreacted diisocyanate. The reaction solution is then poured onto a glass plate and dried to obtain a polyurethane elastomer material having multi-stimulus responsive color change, high mechanical strength, and self-healing properties.

[0029] In the specific implementation process of the embodiment of the present invention: in the above step (1), the structural formula of the diisocyanate is:

[0030] The following are specific embodiments: Example 1

[0031] In this example, a polyurethane elastomer material (w=28, x=5, y=10, z=30) with multi-stimulus responsive color change, high mechanical strength, and self-healing properties was prepared according to the following steps: (1) Add 280.0 mg (0.14 mmol) of polytetrahydrofuran 2000, 131.2 mg (0.50 mmol) of 4,4'-dicyclohexylmethane diisocyanate, 10.0 mg of dibutyltin dilaurate and 3.0 ml of nitrogen-dimethylacetamide into a 10.0 ml round-bottom flask and react at 75°C for three hours under the protection of nitrogen; (2) Lower the reaction temperature to 40°C, dissolve 11.4 mg (0.065 mmol) of adipic acid dihydrazide in 1.0 ml of nitrogen-dimethylacetamide, add the solution to the flask, and continue the reaction for three hours; (3) The reaction temperature was raised to 75°C, and 25.1 mg (0.05 mmol) of rhodamine 6G in ethylene glycol dissolved in 0.5 ml of nitrogen-dimethylacetamide was added to the flask and the reaction was continued for three hours. (4) 26.2 mg (0.195 mmol) of 2,2-bis(hydroxymethyl)propionic acid dissolved in 1.0 ml of nitrogen-dimethylacetamide was added to the flask and the reaction was continued for three hours; (4) After the reaction is complete, 1.0 ml of anhydrous methanol is added and stirred for 0.5 hours to remove the unreacted diisocyanate. The reaction solution is then poured onto a glass plate and placed in a vacuum drying oven for 12 hours to obtain a polyurethane elastomer material with multi-stimulus responsive color change, high mechanical strength, and self-healing properties.

[0032] Figure 1 Infrared spectrum analysis revealed the complete disappearance of the characteristic -NCO peak of the diisocyanate at 2253 cm⁻¹ and the -OH peak of the polyol and chain extender at 3400 cm⁻¹. Simultaneously, the characteristic absorption peak of carbamate (-NHCOO-) appeared at 1702 cm⁻¹. These changes confirmed the complete reaction of the isocyanate and hydroxyl groups in the raw materials, successfully forming the characteristic polyurethane structure.

[0033] Figure 2This is a photograph of the color change of the stimulus-responsive color-changing, high-strength, self-healing polyurethane elastomer material prepared in Example 1 after applying tensile stress. As can be seen from the figure, the stimulus-responsive color-changing, high-strength, self-healing polyurethane elastomer material obtained in Example 1 changes from colorless to pink and its fluorescence changes from blue to orange-red after stress stretching.

[0034] Figure 3 This photograph shows the color change of the multi-stimulus-responsive, color-changing, high-strength, self-healing polyurethane elastomer material prepared in Example 1 after being excited by a 365-nm UV lamp. As can be seen from the figure, the stimuli-responsive, color-changing, high-strength, self-healing polyurethane elastomer material obtained in Example 1 changes from colorless to rose-red, and its fluorescence changes from blue to orange after being excited by a 365-nm UV lamp.

[0035] Figure 4 This photograph shows the color change of the multi-stimulus-responsive, color-changing, high-strength, self-healing polyurethane elastomer material prepared in Example 1 after immersion in 1 M hydrochloric acid. As can be seen from the figure, the multi-stimulus-responsive, color-changing, high-strength, self-healing polyurethane elastomer material obtained in Example 1 changes from colorless to light pink after immersion in an acidic environment.

[0036] Figure 5 The stress-strain curves of the multi-stimulus-responsive color-changing, high-strength, self-healing polyurethane elastomer material prepared in Example 1 before and after healing are shown. As can be seen from the figure, the multi-stimulus-responsive color-changing, high-strength, self-healing polyurethane elastomer material obtained in Example 1 has a maximum tensile stress of 55.1 MPa, an elongation at break of 901%, and a healing efficiency of 91% after heating at 70°C for 24 hours.

[0037] Figure 6 Optical microscope photographs of the multi-stimulus-responsive, color-changing, high-strength, self-healing polyurethane elastomer material prepared in Example 1 before and after healing. As can be seen, scratches sustained by the multi-stimulus-responsive, color-changing, high-strength, self-healing polyurethane elastomer material obtained in Example 1 were completely healed after heating at 70 degrees Celsius for three hours.

[0038] In the product prepared by the above method, w is 28, x is 5, y is 10, and z is 30. Example 2

[0039] This example provides a polyurethane elastomer material (w = 30, x = 6, y = 15, z = 40) with multi-stimulus responsive color change, high mechanical strength, and self-healing properties. The material differs from Example 1 only in that the molar ratio of adipic acid dihydrazide (0.13 mmol) to 2,2-bis(hydroxymethyl)propionic acid is 2:2. The types, amounts, and preparation methods of the remaining components are the same as those in Example 1. Specific performance parameters are detailed in Table 1 below. Example 3

[0040] This example provides a polyurethane elastomer material (w = 35, x = 7, y = 25, z = 70) with multi-stimulus responsive color change, high mechanical strength, and self-healing properties. The material differs from Example 1 only in that the molar ratio of adipic acid dihydrazide (0.195 mmol) to 2,2-bis(hydroxymethyl)propionic acid is 3:1. The types, amounts, and preparation methods of the remaining components are the same as those in Example 1. Specific performance parameters are detailed in Table 1 below. Example 4

[0041] This example provides a polyurethane elastomer material (w=15, x=5, y=10, z=25) with multi-stimulus responsive color change, high mechanical strength, and self-healing properties. The material differs from Example 1 only in that the molar ratio of polytetrahydrofuran 2000 (0.14 mmol) to 4,4'-dicyclohexylmethane diisocyanate is 1:4. The types, amounts, and preparation methods of the remaining components are the same as those in Example 1. Specific performance parameters are detailed in Table 1 below. Example 5

[0042] This example provides a polyurethane elastomer material (w = 40, x = 6, y = 25, z = 60) with multi-stimulus responsive color change, high mechanical strength, and self-healing properties. The material differs from Example 1 only in that the molar ratio of polytetrahydrofuran 2000 (0.14 mmol) to 4,4'-dicyclohexylmethane diisocyanate is 1:3. The types, amounts, and preparation methods of the remaining components are the same as those in Example 1. Specific performance parameters are detailed in Table 1 below. Example 6

[0043] This example provides a polyurethane elastomer material (w = 50, x = 7, y = 30, z = 70) with multi-stimulus responsive color change, high mechanical strength, and self-healing properties. The material differs from Example 1 only in that the molar ratio of polytetrahydrofuran 2000 (0.14 mmol) to 4,4'-dicyclohexylmethane diisocyanate is 1:2.5. The types, amounts, and preparation methods of the remaining components are the same as those in Example 1. Specific performance parameters are detailed in Table 1 below. Example 7

[0044] This example provides a polyurethane elastomer material (w = 60, x = 8, y = 40, z = 80) with multi-stimulus responsive color change, high mechanical strength, and self-healing properties. The material differs from Example 1 only in that the molar ratio of polytetrahydrofuran 2000 (0.14 mmol) to 4,4'-dicyclohexylmethane diisocyanate is 1:2. The types, amounts, and preparation methods of the remaining components are the same as those in Example 1. Specific performance parameters are detailed in Table 1 below. Example 8

[0045] This example provides a polyurethane elastomer material (w=25, x=5, y=12, z=35) with multi-stimulus responsive color change, high mechanical strength, and self-healing properties. The only difference from Example 1 is that polytetrahydrofuran (0.14 mmol) 2000 is replaced with polyethylene glycol 2000 in an equal molar ratio. The types, amounts, and preparation methods of the remaining components are the same as those in Example 1. Specific performance parameters are detailed in Table 1 below. Example 9

[0046] This example provides a polyurethane elastomer material (w=45, x=6, y=18, z=45) with multi-stimulus responsive color change, high mechanical strength, and self-healing properties. The material differs from Example 1 only in that 4,4'-dicyclohexylmethane diisocyanate (0.5 mmol) is replaced with isophorone diisocyanate in an equal molar ratio. The types, amounts, and preparation methods of the remaining components are the same as those in Example 1. Specific performance parameters are detailed in Table 1 below.

[0047] Table 1 Comparison of mechanical properties and healing efficiency of materials in the examples Example Mechanical strength (MPa) Tensile strain (%) Healing efficiency (%) Example 1 55.1 901 91 Example 2 51.4 1086 84 Example 3 47.8 703 66 Example 4 59.2 789 23 Example 5 45.6 1355 89 Example 6 35.4 1494 94 Example 7 27.6 1824 97 Example 8 14.6 2976 99 Example 9 49.7 1202 93 In summary, the present invention significantly endows the material with multiple stimulus-responsive color-changing properties by covalently linking stimulus-responsive color-changing molecules to polyurethane materials. By regulating the structure and ratio of the chain extender, the mechanical properties and self-healing efficiency of the material are effectively and simultaneously improved, showing broad application prospects in the fields of stimulus-responsive color-changing packaging, information anti-counterfeiting encryption, and environmental monitoring. In addition, the preparation process of the present invention is simple, and the obtained material has advantages such as simple structure and high reproducibility, which has strong promotion value.

[0048] The above description is only a preferred embodiment of the present invention. Any technician familiar with this technical field can make various changes and substitutions without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the content defined in the claims.

Claims

1. A polyurethane elastomer material, characterized in that The structural formula of the polyurethane elastomer material is shown below: A is selected from one or more of substituted or unsubstituted phenyl, biphenyl, xylyl, naphthyl, cyclohexyl, butanyl and hexyl, and the substituent is a C4-C6 alkyl, alkoxy or halogen methyl; B is a polyether polyol; w is a positive integer of 10 to 80, x is a positive integer of 4 to 8, y is a positive integer of 20 to 70, and z is a positive integer of 20 to 90.

2. The polyurethane elastomer material according to claim 1, characterized in that: The polyether polyol is selected from polyethylene glycol 200-1000, polytetrahydrofuran 1000-2000, and polycaprolactone diol 1000-2000.

3. The method for preparing the polyurethane elastomer material according to claim 1, characterized in that The method comprises the following steps: (1) reacting diisocyanate and polyether polyol under the action of an organotin catalyst to obtain a prepolymer; The diisocyanate structural formula is OCN-A-NCO, where A is selected from substituted or unsubstituted phenyl, biphenyl, xylyl, naphthyl, cyclohexyl, butane and hexane, and the substituent is C4-C6 alkyl, alkoxy or halogen methyl; (2) reacting the prepolymer with adipic acid dihydrazide to obtain a chain-extended polymer; (3) reacting the chain-extended polymer with rhodamine 6G ethylene glycol to obtain a copolymerized color-changing molecule polymer; (4) reacting the copolymerized color-changing molecule polymer with 2,2-bis(hydroxymethyl)propionic acid to obtain a crude material product; (5) Methanol is added to the crude material to remove unreacted isocyanate to obtain a polyurethane elastomer material.

4. The method for preparing the polyurethane elastomer material according to claim 3, wherein: In step (1), the organic tin catalyst used is selected from dibutyltin dineoctanoate, dimethyltin dineoctanoate, methyltin mercaptan, dibutyltin dilaurate, and di-n-octyltin dilaurate.

5. The method for preparing the polyurethane elastomer material according to claim 3, characterized in that: In step (1), the molar ratio of the diisocyanate to the polyether polyol is 4:(1-4), and the reaction temperature is 30-100°C.

6. The method for preparing the polyurethane elastomer material according to claim 3, wherein: In step (1), the diisocyanate structural formula is, 7. The method for preparing the polyurethane elastomer material according to claim 3, characterized in that: In step (2), the molar ratio of diisocyanate to adipic acid dihydrazide is 8:(1-8), and the reaction temperature is 30-100°C.

8. The method for preparing the polyurethane elastomer material according to claim 3, wherein: In step (3), the molar ratio of diisocyanate to rhodamine 6G glycol is 18:(1-2), and the reaction temperature is 30-100°C.

9. The method for preparing the polyurethane elastomer material according to claim 3, characterized in that: In step (4), the molar ratio of diisocyanate to 2,2-bis(hydroxymethyl)propionic acid is 8:(1-8), and the reaction temperature is 30-100°C.

10. Use of the polyurethane elastomer material according to claim 1 in stimulus-responsive color-changing packaging, information anti-counterfeiting encryption, or environmental monitoring.

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