Polyurethane elastomers employing squaric amide chain extenders and methods of making the same
By using a mixture of squaramide and small molecule diols as chain extenders, polyurethane elastomers were prepared, solving the problems of complex synthesis and low solubility in existing technologies, and improving the mechanical properties of polyurethane elastomers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING FORESTRY UNIV
- Filing Date
- 2024-10-12
- Publication Date
- 2026-08-04
AI Technical Summary
Existing polyurethane elastomers are complex to synthesize and contain chain extenders with multiple hydrogen bonds, which have low solubility in polar solvents, making them unsuitable for large-scale production.
A mixture of squaramide and small molecule diols was used as a chain extender, with squaramide accounting for 5.0-50.0% of the total mass of the chain extender. The mixture was reacted with polyol oligomers and isocyanates under specific conditions to prepare polyurethane elastomers.
The mechanical properties of polyurethane elastomers have been improved, particularly achieving a balance in tensile strength, elongation, and material toughness.
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Abstract
Description
Technical Field
[0001] This application belongs to the field of polyurethane elastomer technology, and more specifically, relates to polyurethane elastomers using squaramide chain extension and their preparation methods. Background Technology
[0002] Polyurethane (PU) is one of the most commonly used polymers, possessing a variety of properties. It can be used in paints, coatings, synthetic rubbers, foams, fibers, adhesives, etc., and is widely applied in the automotive industry, construction engineering, and biomedicine. PU is a block copolymer, consisting of a segmented block structure composed of hard segments (HS) made of isocyanate and chain extenders and soft segments (SS) of polyols. PU exhibits excellent mechanical properties, such as high elongation, toughness, and strain recovery, which are caused by microphase separation due to the thermodynamic incompatibility between HS and SS. When microphase separation occurs, HS domains are dispersed in the SS matrix, and HS are bonded together by hydrogen bonds to form microphases, acting as physical crosslinking points within the structural domains. Therefore, its tensile properties are related to the microphase separation structure.
[0003] Currently, the structure-property relationship of polyurethane (PU) has been extensively studied, and customized properties can be obtained through careful design of the soft and hard segment structures. Due to the high directionality and bonding strength of hydrogen bonds, they are beneficial for microphase separation and the formation of independent microregions within the soft and hard segments. Previous studies have demonstrated that introducing groups with multiple hydrogen bond structures, such as urea bonds, ureidopyrimidinones (Upy), and hydrazides, into the PU backbone or side chains to form double, quadruple, and multiple hydrogen bonds, respectively, can significantly improve the microphase separation structure. Previous research has mainly focused on systems capable of forming multiple hydrogen bonds; however, the synthesis of these polyurethane or polyurea elastomers is complex, and chain extenders containing multiple hydrogen bonds have low solubility in common polar solvents, making them unsuitable for large-scale production and preparation. Summary of the Invention
[0004] In view of the above-mentioned problems in the prior art, the purpose of this application is to provide a polyurethane elastomer using squaramide chain extension, and another purpose of this application is to provide a method for preparing the polyurethane elastomer.
[0005] To solve the above problems, the technical solution adopted in this application is as follows: In a first aspect, this application provides a polyurethane elastomer using squaramide chain extender, wherein the chain extender is a mixture of squaramide and small molecule diol, and the squaramide accounts for 5.0 to 50.0% of the total mass of the chain extender.
[0006] In the first aspect of this application, the small molecule diol is one or more of ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.
[0007] Secondly, this application provides a method for preparing the above-mentioned polyurethane elastomer, characterized in that a mixture of squaramide and small molecule diol is used as a chain extender, wherein squaramide accounts for 5.0 to 50.0% of the total mass of the chain extender.
[0008] In the second aspect of this application, the small molecule diol is one or more of ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.
[0009] In the second aspect of this application, the chain extender accounts for 0.30 to 4.50% of the mass of the polyurethane.
[0010] In the second aspect of this application, a catalyst is added to a polyol oligomer, a measured amount of isocyanate is added dropwise, and after the addition is complete, an N,N-dimethylformamide solution containing a chain extender is added dropwise at a concentration of 30-70%. After the addition is complete, the reaction continues for 1-3 hours. The above reaction is carried out at 60-85°C. After the solvent is removed from the solution after the reaction is complete, the polyurethane elastomer is obtained.
[0011] In the second aspect of this application, the polyol oligomer is at least one of polytetrahydrofuran diol, polyadipate diol ester diol, polycaprolactone diol, and polycarbonate diol, and the molecular weight of the polyol oligomer is 600~4000 g / mol.
[0012] In the second aspect of this application, when the polyol oligomer is polyadipate diol ester diol, the diol monomer in the polyadipate diol is at least one of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and pentanediol.
[0013] In the second aspect of this application, the catalyst is stannous octoate, and the amount used accounts for 0.005% of the mass of the polyol oligomer.
[0014] In the second aspect of this application, the isocyanate used is at least one of IPDI, HDI, XDI, HMDI, TDI, and MDI.
[0015] Compared to existing technologies, the beneficial effects of this application are at least as follows: At the recommended ratio of squaramide to diol, compared with polyurea elastomers containing equimolar mass of squaramide chain extenders or polyurethane elastomers containing diol chain extenders, in the polyurethane elastomer prepared in this application, squaramide acts as a physical crosslinking point to increase strength, while diol improves molecular chain migration. Their synergistic effect improves mechanical properties, and the polyurethane elastomer achieves a balance in terms of tensile strength, elongation, and material toughness.
[0016] The remaining advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practice of the embodiments of this application. Detailed Implementation
[0017] To make the purpose, technical solutions, and beneficial effects of this application clearer, the various embodiments of this application will be described in detail below. However, the embodiments described below are exemplary and are only used to explain the content of this application, and should not be construed as limiting the content of this application. Those skilled in the art will understand that many technical details are presented in the various embodiments of this application to enable readers to better understand this application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in this application can be implemented. The division of the various embodiments below is for the convenience of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.
[0018] This application employs a novel structural unit—squamamide (3,4-diamino-3-cyclobutene-1,2-dione, CAS No.: 5231-89-0)—in combination with a common diol chain extender. Within a certain proportion range, the polyurethane elastomer prepared using this unit is superior to polyurethanes prepared using either squamamide or the diol alone. Squamamide is a class of cyclobutene derivatives with a rigid conformation. Its molecular structure contains two closely spaced NH hydrogen bond donors and two C=O hydrogen bond acceptors, exhibiting unique physical and chemical properties and finding wide application in organocatalysis, molecular recognition, and self-assembly. Structurally, squamamide is similar to urea bonds, both capable of providing hydrogen bonds through NH atoms as hydrogen bond donors and accepting hydrogen bonds through O atoms as hydrogen bond acceptors. However, unlike urea groups, the four-membered ring structure of squamamide expands its range of hydrogen bond acceptance and donation. The two sets of NH bonds are spaced 2.8 Å apart, giving it a greater advantage in forming hydrogen bonds. Furthermore, the cyclobutene dione system in the square amide unit can form a resonance structure with two positive charges, which is aromatic according to Hückel's aromaticity rule, and the aromaticity of the square amide is enhanced after forming a stable hydrogen-bonded complex.
[0019] This application provides a polyurethane elastomer using squaramide chain extender, wherein the chain extender is a mixture of squaramide and small molecule diol.
[0020] This application provides a method for preparing the polyurethane elastomer using square amide chain extension as described above. In specific implementation, the preparation method can be carried out according to the steps described in Examples 1, 2, 3 and 4 below.
[0021] Example 1 Polytetrahydrofuran polyether with Mw=2000 was selected as the soft segment, and 1,4-butanediol and squaramide were mixed for chain extension. IPDI was selected as the isocyanate. The molar ratio of polydiol, chain extender and isocyanate was 1:0.5:1.5. The specific feeding method is shown in Table 1.
[0022] Table 1. Feed ratio of Example 1 and control sample
[0023] 100g of polytetrahydrofuran polyether was dehydrated at 120℃ for 2 hours, then cooled to 40℃ and 5mg of stannous octoate was added. 16.67g of IPDI was then added dropwise at 65℃. After the addition was complete, a solution of N,N-dimethylformamide (DMF) containing 0.56g of squaramide and 1.80g of 1,4-butanediol was added dropwise, with a solution concentration of 35%. After the addition was complete, the temperature was raised to 85℃ and the reaction continued for 1.5 hours. After the solvent was removed from the reacted solution, the polyurethane elastomer of Example 1 containing squaramide chain extension was obtained.
[0024] In the above steps, the chain extender used was 2.25g of 1,4-butanediol or 2.80g of squaramide, respectively. Following the same reaction steps, control sample 1a and control sample 1b were obtained respectively.
[0025] The mechanical properties of the aforementioned polyurethane elastomer were tested by cutting standard dumbbell-shaped test samples with a gauge length of 20 mm, a width of 4 mm, and a total length of 75 mm. The tensile speed was set to 250 ± 50 mm / min to obtain tensile strength and elongation. Tensile toughness was then obtained by integrating the stress-strain curve, i.e., tensile toughness = (fracture load * original cross-sectional area of the specimen) / (elongation of the specimen after fracture). Example 1: Tensile strength 15.3 MPa, elongation 1200%, toughness 23.89 MJ / m 3 The control sample 1a had a tensile strength of 4.3 MPa, an elongation of 830%, and a toughness of 4.56 MJ / m. 3 The control sample 1b had a tensile strength of 8.5 MPa, an elongation of 750%, and a toughness of 8.76 MJ / m. 3 .
[0026] Example 2 Polybutylene adipate diol with Mw=4000 was selected as the soft segment, and 1,4-butanediol and squaramide were mixed for chain extension. TDI and HDI were mixed isocyanates. The molar ratio of polydiol, chain extender and isocyanate was 1:1.5:2.5. The specific feeding method is shown in Table 2.
[0027] Table 2. Feed ratio of Example 2 and control sample
[0028] 100g of polybutylene adipate diol was dehydrated at 120°C for 2 hours. After cooling to 40°C, 5mg of stannous octoate was added, followed by dropwise addition of a mixed isocyanate (8.71g of TDI mixed with 2.10g of HDI) at 65°C. After the addition was complete, a solution of N,N-dimethylformamide (DMF) containing 1.40g of squaramide and 2.25g of 1,4-butanediol was added dropwise, with a solution concentration of 38%. After the addition was complete, the temperature was raised to 85°C and the reaction continued for 1.5 hours. After the solvent was removed from the reacted solution, the polyurethane elastomer of Example 2 containing squaramide chain extension was obtained.
[0029] In the above steps, the chain extender used was 3.38g of 1,4-butanediol or 4.20g of squaramide, respectively. Following the same reaction steps, control sample 2a and control sample 2b were obtained respectively.
[0030] Following the method of Example 1, the mechanical properties of the above-mentioned polyurethane elastomer were tested. Example 2 showed a tensile strength of 76.8 MPa, an elongation of 1500%, and a toughness of 149.9 MJ / m. 3 The control sample 2a had a tensile strength of 24.3 MPa, an elongation of 770%, and a toughness of 24.56 MJ / m. 3 The control sample 2b had a tensile strength of 48.5 MPa, an elongation of 440%, and a toughness of 38.76 MJ / m. 3 .
[0031] Example 3 Polycaprolactone diol with Mw=1000 was selected as the soft segment, ethylene glycol and squaramide were mixed for chain extension, and MDI was selected as the isocyanate. The molar ratio of polydiol, chain extender and isocyanate was 1:0.3:1.3. The specific feeding method is shown in Table 3.
[0032] Table 3. Feed ratio of Example 3 and control sample
[0033] 100g of polycaprolactone diol was dehydrated at 120℃ for 2 hours, then cooled to 40℃ and 5mg of stannous octoate was added. 35.53g of MDI was then added dropwise at 65℃. After the addition was complete, a solution of N,N-dimethylformamide (DMF) containing 0.34g of squaramide and 1.68g of ethylene glycol was added dropwise, with a solution concentration of 35%. After the addition was complete, the temperature was raised to 85℃ and the reaction continued for 1.5 hours. After the solvent was removed from the reacted solution, the polyurethane elastomer of Example 3 containing squaramide chain extension was obtained.
[0034] In the above steps, the chain extender used was 1.86g of ethylene glycol or 3.36g of squaramide, respectively. Following the same reaction steps, control sample 3a and control sample 3b were obtained respectively.
[0035] Following the method described in Example 1, the mechanical properties of the above-mentioned polyurethane elastomer were tested. Example 3 showed a tensile strength of 35.3 MPa, an elongation of 680%, and a toughness of 89.3 MJ / m. 3 The control sample 3a had a tensile strength of 14.6 MPa, an elongation of 830%, and a toughness of 54.56 MJ / m. 3 The control sample 3b had a tensile strength of 38.5 MPa, an elongation of 350%, and a toughness of 38.76 MJ / m. 3 .
[0036] Example 4 Poly(diol adipate) diol (i.e., polydiol, polyester diol) with a Mw of 2000 was selected as the soft segment. The diol was a mixture of 1,4-butanediol, ethylene glycol, and pentanediol, with a mass ratio of 85:10:5. A chain extender was created by mixing 1,4-butanediol and squaramide. IPDI was selected as the isocyanate, and the molar ratio of polydiol, chain extender, and isocyanate was 1:1:2. Specific feeding details are shown in Table 4.
[0037] Table 4. Feed ratio of Example 4 and control sample
[0038] 100g of polyester glycol was dehydrated at 120℃ for 2 hours, then cooled to 40℃ and 5mg of stannous octoate was added. 22.23g of IPDI was then added dropwise at 65℃. After the addition was complete, a solution of N,N-dimethylformamide (DMF) containing 2.24g of squaramide and 2.70g of ethylene glycol was added dropwise, with a solution concentration of 35%. After the addition was complete, the temperature was raised to 85℃ and the reaction continued for 1.5 hours. After the solvent was removed from the reacted solution, the polyurethane elastomer of Example 4 containing squaramide chain extension was obtained.
[0039] In the above steps, 4.51 g of 1,4-butanediol or 5.60 g of squaramide were used as chain extenders, and control sample 4a and control sample 4b were obtained respectively by following the same reaction steps.
[0040] Following the method described in Example 1, the mechanical properties of the above-mentioned polyurethane elastomer were tested. Example 4 showed a tensile strength of 85.3 MPa, an elongation of 660%, and a toughness of 119.3 MJ / m. 3 The control sample 3a had a tensile strength of 35.6 MPa, an elongation of 830%, and a toughness of 74.56 MJ / m. 3 The control sample 3b had a tensile strength of 68.5 MPa, an elongation of 380%, and a toughness of 68.76 MJ / m. 3 .
[0041] In this application, the catalyst can also be other conventional polyurethane elastomer catalysts, and the amount used is also conventional.
[0042] It is understood that the specific parameters of each step in Examples 1 to 4 above should not constitute any limitation on the specific implementation of this application. Each example describes how to prepare polyurethane elastomer by extending the chain of squaramide to obtain the squaramide chain-extended polyurethane elastomer of this application. The implementation details involved are preferred examples, and the specific parameters can also be selected with reference to the following range.
[0043] In this application, the small molecule diol can be one or a combination of two or more of ethylene glycol, 1,4-butanediol, and 1,6-hexanediol. The recommended ratio of the small molecule diol to the squaramide is 5.0% to 50.0% of the total mass of the chain extender, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%. The chain extender accounts for 0.30% to 4.50% of the mass of the polyurethane, such as 0.3%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, and 4.5%.
[0044] In this application, the polyol oligomer is at least one selected from polytetrahydrofuran diol, polyadipate diol, polycaprolactone diol, and polycarbonate diol, with a molecular weight of 600-4000 g / mol, for example, 600 g / mol, 1000 g / mol, 1500 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol, 3500 g / mol, and 4000 g / mol. When the polyol oligomer is polyadipate diol, the diol monomer in the polyadipate diol is at least one selected from ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and pentanediol. The isocyanate used is at least one selected from IPDI, HDI, XDI, HMDI, TDI, and MDI.
[0045] In this application, the N,N-dimethylformamide solution of the chain extender has a concentration of 30-70%, for example, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%. After the chain extender is added dropwise, the reaction continues for 1-3 hours, which can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours. The elastomer preparation process is carried out at 60-85°C, such as 60°C, 65°C, 70°C, 75°C, 80°C, or 85°C.
Claims
1. A polyurethane elastomer employing squarilamide chain extension, characterized in that, The chain extender used is a mixture of squaramide and small molecule diol, with squaramide accounting for 5.0~50.0% of the total mass of the chain extender; The small molecule diol is one or more of ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.
2. Process for the preparation of polyurethane elastomers, characterized in that, A mixture of squaramide and small molecule diols is used as a chain extender, with squaramide accounting for 5.0~50.0% of the total mass of the chain extender; The small molecule diol is one or more of ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.
3. The process for the preparation of a polyurethane elastomer according to claim 2, characterized in that, The chain extender accounts for 0.30 to 4.50% of the mass of polyurethane.
4. The process for the preparation of a polyurethane elastomer according to any one of claims 2 to 3, characterized in that, A catalyst is added to the polyol oligomer, and a measured amount of isocyanate is added dropwise. After the addition is complete, an N,N-dimethylformamide solution containing a chain extender is added dropwise at a concentration of 30-70%. The reaction continues for 1-3 hours after the addition is complete. The above reaction is carried out at 60-85°C. After the solvent is removed from the solution after the reaction is complete, the polyurethane elastomer is obtained.
5. The process for the preparation of a polyurethane elastomer according to claim 4, characterized in that, The polyol oligomer is at least one of polytetrahydrofuran diol, polyadipate diol, polycaprolactone diol, and polycarbonate diol, and the molecular weight of the polyol oligomer is 600~4000 g / mol.
6. The process for the preparation of a polyurethane elastomer according to claim 5, characterized in that, When the polyol oligomer is polyadipate diol ester diol, the diol monomer in the polyadipate diol is at least one of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and pentanediol.
7. The method of producing a polyurethane elastomer according to claim 4, characterized by, The catalyst is stannous octoate, and its amount accounts for 0.005% of the mass of the polyol oligomer.
8. The method of producing a polyurethane elastomer according to claim 4, characterized by, The isocyanate used is at least one of IPDI, HDI, XDI, HMDI, TDI, and MDI.