Telechelic polyurethanes, methods for their preparation and uses

Abstract

To provide telechelic polyurethane, and a preparation method and use of the same.SOLUTION: Telechelic polyurethane as a high strength and high toughness polyurethane elastomer material is obtained by introducing an ureidopyrimidinone group in 2-amino-4-hydroxy-6-methylpyrimidine into a polyester polyol segment, and controlling its microphase structure. The ureidopyrimidinone group in the polymer segment forms a quadruple hydrogen bond network by dimerization, its reversible characteristic derives phase separation, is useful for achievement of huge energy dissipation, also can form stable microcrystal at an ambient temperature by a π-π stacking interaction, improves mechanical strength of a polyurethane material, on the other hand, presence of a rich and weak hydrogen bonding action on a soft segment of a polymer chain imparts ultrahigh toughness to the material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of polyurethane materials, in particular to telechelic polyurethanes, their preparation methods and uses. [Background technology]

[0002] In recent years, polyurethane has attracted attention due to its excellent comprehensive performance, recyclability and wide application prospects. As a new polymer material, polyurethane has advantages such as excellent abrasion resistance, ozone resistance, low temperature resistance and corrosion resistance, and has wide application prospects in fields such as aerospace, automobiles, textiles, construction, medicine, intelligent detection, etc.

[0003] However, the inherent tradeoff between strength and toughness of conventional polyurethane materials has severely limited their practical application in areas such as automotive coatings, wearable electronic devices, soft robots, flexible electronics, and biomedicine. Summary of the Invention [Problem to be solved by the invention]

[0004] In view of this, it is an object of the present invention to provide telechelic polyurethanes, their preparation methods and uses. The telechelic polyurethanes prepared according to the present invention have both toughness and strength. [Means for solving the problem]

[0005] In order to achieve the above object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a telechelic polyurethane, comprising the steps of: Polyester polyol, polyether amine of mixture (Or, after obtaining the polyurethane polymer described below, mix in a diamine chain extender.) to obtain a mixed solution; a step of mixing the mixed solution, a diisocyanate, a catalyst, and an organic solvent to carry out a prepolymerization reaction to obtain a polyurethane prepolymer; mixing the polyurethane prepolymer, 2-amino-4-hydroxy-6-methylpyrimidine, and an organic solvent to carry out a first addition reaction to obtain an addition product; and mixing the addition product, a crosslinker, and an organic solvent to carry out a second addition reaction to obtain the telechelic polyurethane.

[0007] Preferably, the molar ratio of the polyester polyol, polyether amine, diisocyanate, 2-amino-4-hydroxy-6-methylpyrimidine and crosslinking agent is 3-30:3-30:9-90:3-30:1-10.

[0008] Preferably, the average molecular weight of the polyester polyol is 1,000 to 3,000, and the polyester polyol includes one or more of polycarbonate diol, polycaprolactone diol, and polyester polyol.

[0009] Preferably, the diisocyanate comprises one or more of hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0010] Preferably, the temperature of the prepolymerization reaction is 60 to 100° C., the time is 2 to 3 hours, and the prepolymerization reaction is carried out in a protective atmosphere.

[0011] Preferably, the temperature of the first addition reaction is 60 to 100° C., the time is 1 to 3 hours, and the first addition reaction is carried out in a protective atmosphere.

[0012] Preferably, the crosslinking agent is a triol-based crosslinking agent or a triamine-based crosslinking agent, the triol-based crosslinking agent including one or more of trimethylolpropane, trimethylolethane, and glycerin, and the triamine-based crosslinking agent including tris(2-aminoethyl)amine.

[0013] Preferably, the temperature of the second addition reaction is 60 to 100° C., the time is 1 to 3 hours, and the second addition reaction is carried out in a protective atmosphere.

[0014] The present invention further provides a telechelic polyurethane prepared by the preparation method described in the above technical solution.

[0015] The present invention further provides the use of the telechelic polyurethanes described in the above technical solutions in the fields of aerospace, automobiles, textiles, construction, medicine and intelligent detection.

[0016] The present invention relates to a method for preparing telechelic polyurethanes, comprising the steps of: of mixture (Or, after obtaining the polyurethane polymer described below, mix in a diamine chain extender.) to obtain a mixed solution; mixing the mixed solution, a diisocyanate, a catalyst, and an organic solvent to perform a prepolymerization reaction to obtain a polyurethane prepolymer; mixing the polyurethane prepolymer, 2-amino-4-hydroxy-6-methylpyrimidine, and an organic solvent to perform a first addition reaction to obtain an addition product; and mixing the addition product, a crosslinker, and an organic solvent to perform a second addition reaction to obtain the telechelic polyurethane.

[0017] This invention provides neuron-inspired, high-toughness telechelic polyurethanes. By incorporating ureidopyrimidinone groups from 2-amino-4-hydroxy-6-methylpyrimidine into polyester polyol segments and adding a triol or triamine crosslinker, we have achieved high-strength, high-toughness polyurethane elastomers. The ureidopyrimidinone groups in the polymer segments dimerize to form a quadruple hydrogen-bonded network. Their reversible nature not only induces phase separation and contributes to massive energy dissipation, but also allows the formation of stable microcrystals at ambient temperatures through π-π stacking interactions, improving the mechanical strength of the polyurethane material. The abundant weak hydrogen-bonding interactions in the soft segments of the polymer chains impart ultra-high toughness to the material. Furthermore, the introduction of multifunctional chemical crosslinkers contributes to the construction of a robust chemical network crosslinking point, imparting excellent mechanical properties to the polyurethane material. Due to the synergistic effect of dynamically reversible hierarchical hydrogen bonds and stable covalent bonds present in the polymer network structure, the resulting polyurethane films exhibit high tensile strength and excellent toughness. [Effects of the Invention]

[0018] The telechelic polymer prepared by the present invention is a liquid polymer with reactive functional groups at both ends of the molecule, and can be used as liquid rubber, paint, adhesive, sealant, etc. Finally, the active end groups can be linked or crosslinked to form high molecular weight polymers through their interaction, which is of great significance and value for expanding the use of polyurethane materials in fields such as aerospace, automobiles, textiles, construction, medicine, and intelligent detection. Furthermore, the preparation method of the present invention has the advantages of being highly efficient, safe, and environmentally friendly, and the prepared polyurethane elastomer combines properties such as high strength, high toughness, film-forming ability of polymer materials, and excellent heat resistance, providing a new concept for the development of next-generation high-strength, high-toughness polyurethane materials. [Brief explanation of the drawings]

[0019] [Figure 1]1 is a reaction flow chart for preparing telechelic polyurethane in Example 1. [Figure 2] FIG. 2 is a schematic diagram of stress-strain curves of samples in Examples 1 to 3. [Figure 3] 1 shows stress-strain curves of the sample prepared in Example 1 at different tensile speeds. [Figure 4] 1 is a schematic diagram of the heat loss curve of the sample prepared in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention provides a method for preparing a telechelic polyurethane, comprising the steps of: Polyester polyol, polyether amine of mixture (Or, after obtaining the polyurethane polymer described below, mix in a diamine chain extender.) to obtain a mixed solution; a step of mixing the mixed solution, a diisocyanate, a catalyst, and an organic solvent to carry out a prepolymerization reaction to obtain a polyurethane prepolymer; mixing the polyurethane prepolymer, 2-amino-4-hydroxy-6-methylpyrimidine, and an organic solvent to carry out a first addition reaction to obtain an addition product; and mixing the addition product, a crosslinker, and an organic solvent to carry out a second addition reaction to obtain the telechelic polyurethane.

[0021] In the present invention, all raw materials used are commercially available products in this field unless otherwise specified.

[0022] The present invention relates to a polyester polyol, a polyether amine of mixture (Or, after obtaining the polyurethane polymer described below, mix in a diamine chain extender.) A mixed solution is obtained.

[0023] In the present invention, the average molecular weight of the polyester polyol is preferably 1,000 to 3,000, and the polyester polyol preferably contains one or more of polycarbonate diol, polycaprolactone diol, and polyester polyol.

[0024] In the present invention, the polyetheramine is preferably D230, D400 or D2000.

[0025] In the present invention, the diamine chain extender is preferably adipic acid dihydrazide, 4,4'-diaminodicyclohexylmethane, 4,4'-dithiodianiline, or 2,2'-ethylenedianiline.

[0026] In the present invention, the mixing is preferably carried out in a three-necked flask.

[0027] In the present invention, the mixing temperature is preferably 100 to 120°C, the time is preferably 30 to 120 minutes, the mixing is preferably performed by stirring in an oil bath under a nitrogen atmosphere, and the function of the mixing is to remove water and dry the mixture.

[0028] After the mixed liquid is obtained, the present invention mixes the mixed liquid, diisocyanate, catalyst, and organic solvent to carry out a prepolymerization reaction, thereby obtaining a polyurethane prepolymer.

[0029] In the present invention, the diisocyanate includes one or more of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), and 4,4'-dicyclohexylmethane diisocyanate (HMDI).

[0030] In the present invention, the catalyst is preferably dibutyltin dilaurate (DBTDL).

[0031] In the present invention, the molar ratio of the diisocyanate to the catalyst is preferably 10 to 30:1.

[0032] In the present invention, the prepolymerization reaction is preferably carried out at a temperature of 60 to 100°C for 2 to 3 hours in a protective atmosphere. During the prepolymerization reaction, the polyester polyol and polyether amine are all reacted with diisocyanate, and not only the prepolymerization reaction product but also a substance resulting from the reaction of polyether amine with diisocyanate is present in the reaction system.

[0033] In the present invention, the protective atmosphere is preferably N2.

[0034] In the present invention, the organic solvent preferably includes one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), toluene, and tetrahydrofuran (THF). In the present invention, it is preferable to control the viscosity of the reaction product by adjusting the amount of the organic solvent to prevent gelation.

[0035] In the present invention, it is preferable that after the mixed solution is cooled to 60 to 100°C, the mixture of the diisocyanate and the organic solvent is added dropwise to a reaction flask, the catalyst is added dropwise, and the prepolymerization reaction is carried out in a N2 atmosphere to obtain the polyurethane prepolymer.

[0036] After the polyurethane prepolymer is obtained, the present invention mixes the polyurethane prepolymer, 2-amino-4-hydroxy-6-methylpyrimidine (UPy) and an organic solvent to carry out a first addition reaction, thereby obtaining an addition product.

[0037] In the present invention, the organic solvent preferably includes one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), toluene, and tetrahydrofuran (THF), and more preferably matches the organic solvent used in the prepolymerization reaction.

[0038] In the present invention, it is preferable to first ultrasonically mix the 2-amino-4-hydroxy-6-methylpyrimidine and the organic solvent to obtain a 2-amino-4-hydroxy-6-methylpyrimidine solution, and then add the 2-amino-4-hydroxy-6-methylpyrimidine solution dropwise to the polyurethane prepolymer.

[0039] In the present invention, the concentration of the 2-amino-4-hydroxy-6-methylpyrimidine solution is preferably 0.01 g / mL.

[0040] In the present invention, the temperature of the first addition reaction is preferably 60 to 100° C., the time is preferably 1 to 3 hours, and the first addition reaction is preferably carried out in a protective atmosphere.

[0041] After the addition product is obtained, the present invention mixes the addition product, a crosslinking agent, and an organic solvent to carry out a second addition reaction, thereby obtaining the telechelic polyurethane.

[0042] In the present invention, the temperature of the second addition reaction is preferably 60 to 100° C., the time is preferably 1 to 3 hours, and the second addition reaction is preferably carried out in a protective atmosphere.

[0043] In the present invention, the crosslinking agent is preferably a triol-based crosslinking agent or a triamine-based crosslinking agent, and the triol-based crosslinking agent preferably includes one or more of trimethylolpropane (TMP), trimethylolethane (TME), and glycerin, and the triamine-based crosslinking agent preferably includes tris(2-aminoethyl)amine (TAN).

[0044] In the present invention, the organic solvent preferably includes one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), toluene, and tetrahydrofuran (THF), and more preferably matches the organic solvent used in the prepolymerization reaction.

[0045] In the present invention, it is preferable that first, the crosslinking agent and the organic solvent are ultrasonically mixed to obtain a crosslinking agent solution, and then the crosslinking agent solution is added dropwise to the addition product.

[0046] In the present invention, the molar ratio of the polyester polyol, polyether amine, diisocyanate, 2-amino-4-hydroxy-6-methylpyrimidine and crosslinking agent is preferably 3-30:3-30:9-90:3-30:1-10.

[0047] After the second addition reaction is completed, the present invention involves pouring the resulting solution into a polytetrafluoroethylene mold and subjecting it to vacuum drying at 60 to 100°C for 48 hours to remove the remaining solvent, thereby obtaining the telechelic polyurethane.

[0048] The present invention further provides a telechelic polyurethane prepared by the preparation method described in the above technical solution.

[0049] The present invention further provides the use of the telechelic polyurethanes described in the above technical solutions in the fields of aerospace, automobiles, textiles, construction, medicine and intelligent detection.

[0050] In the present invention, the specific method of use is not particularly limited, and any method well known to those skilled in the art may be employed.

[0051] In order to further illustrate the present invention, the telechelic polyurethane provided by the present invention, its preparation method and use will be described in detail below with reference to examples, which are not to be construed as limiting the scope of protection of the present invention.

[0052] Example 1 (1) First, 6.00 g / 3 mmol of polycarbonate diol (PCDL-2000) with a molecular weight of 2000 g / mol and 0.69 g / 3 mmol of polyetheramine (D230) with a molecular weight of 230 g / mol were weighed and mixed, and then placed in a three-neck flask and stirred for 30 minutes in an oil bath at 120°C under a N2 atmosphere. (2) Next, the temperature of the above mixture was cooled to 80°C, and then 30 mL of N,N-dimethylformamide (DMF) was weighed out as a solvent, and isophorone was added. J 2.20 g / 9 mmol of isocyanate (IPDI) was weighed and added dropwise to a reaction flask. 0.03 g of dibutyltin dilaurate (DBTDL) was added dropwise as a catalyst. The reaction was carried out in a N2 atmosphere for 2 h. To prevent gelation, the amount of organic solvent was appropriately adjusted to control the viscosity of the reaction mixture, yielding a prepolymer. (3) After the preparation of the prepolymer was completed, 0.38 g / 3 mmol of 2-amino-4-hydroxy-6-methylpyrimidine (UPy) was weighed out, and 3.8 ml of a DMF solution (concentration: 0.01 g / ml) was measured and added dropwise to the reaction flask. The mixture was reacted at 80°C for 60 minutes under a N2 atmosphere. (4) 0.134 g / 1 mmol of trimethylolpropane (TMP) was weighed and dissolved in 5 mL of DMF solvent. After complete dissolution, the solution was added dropwise to the reaction flask and the reaction was carried out at 80°C for 60 minutes under a N2 atmosphere. (5) After the reaction was completed, the solution was poured into a polytetrafluoroethylene mold and vacuum dried at 80°C for 48 hours to remove the residual solvent. The sample was named PUD-UPy.

[0053] FIG. 1 is a reaction flow chart for the preparation of telechelic polyurethane in Example 1.

[0054] Example 2 (1) First, 6.00 g / 3 mmol of polycarbonate diol (PCDL-2000) with a molecular weight of 2000 g / mol was weighed and placed in a three-neck flask. The mixture was stirred in an oil bath at 120 °C under a N2 atmosphere for 30 minutes to remove water and dry the mixture. (2) Next, the temperature of the above mixture was cooled to 80°C, and then 30 mL of N,N-dimethylformamide (DMF) was weighed out as a solvent, and isophorone was added. J 2.20 g / 9 mmol of isocyanate (IPDI) was weighed and added dropwise to a reaction flask. 0.03 g of dibutyltin dilaurate (DBTDL) was added dropwise as a catalyst. The reaction was carried out in a N2 atmosphere for 2 h. To prevent gelation, the amount of organic solvent was appropriately adjusted to control the viscosity of the reaction mixture, yielding a prepolymer. (3) After the preparation of the prepolymer was completed, 0.631 g / 3 mmol of 4,4'-diaminodicyclohexylmethane (DDM) with a molecular weight of 210.37 g / mol was weighed and dissolved in DMF. After it was fully dissolved, it was added dropwise to the reaction system. (4) Furthermore, 0.38 g / 3 mmol of 2-amino-4-hydroxy-6-methylpyrimidine (UPy) was weighed out, and 3.8 ml of a DMF solution (concentration: 0.01 g / ml) was measured and added dropwise to the reaction flask, followed by reaction at 80°C for 60 minutes under a N2 atmosphere. (5) 0.134 g / 1 mmol of trimethylolpropane (TMP) was weighed and dissolved in 5 mL of DMF solvent. After complete dissolution, the solution was added dropwise to a reaction flask and the reaction was carried out at 80°C for 60 minutes under a N2 atmosphere. (6) After the reaction was completed, the solution was poured into a polytetrafluoroethylene mold and vacuum dried at 80°C for 48 hours to remove the residual solvent. The sample was named PUD-UPy-1.

[0055] Example 3 (1) First, 6.00 g / 3 mmol of polycarbonate diol (PCDL-2000) with a molecular weight of 2000 g / mol was weighed and placed in a three-neck flask. The mixture was stirred in an oil bath at 120 °C under a N2 atmosphere for 30 minutes to remove water and dry the mixture. (2) Next, the temperature of the above mixture was cooled to 80°C, and then 30 mL of N,N-dimethylformamide (DMF) was weighed out as a solvent, and isophorone was added. J2.20 g / 9 mmol of isocyanate (IPDI) was weighed and added dropwise to a reaction flask. 0.03 g of dibutyltin dilaurate (DBTDL) was added dropwise as a catalyst. The reaction was carried out in a N2 atmosphere for 2 h. To prevent gelation, the amount of organic solvent was appropriately adjusted to control the viscosity of the reaction mixture, yielding a prepolymer. (3) After the preparation of the prepolymer was completed, 0.523 g / 3 mmol of adipic acid dihydrazide (ADH) with a molecular weight of 174.20 g / mol was weighed and dissolved in DMF. After the solution was fully dissolved, it was added dropwise to the reaction system. (4) Furthermore, 0.38 g / 3 mmol of 2-amino-4-hydroxy-6-methylpyrimidine (UPy) was weighed out, and 3.8 ml of a DMF solution (concentration: 0.01 g / ml) was measured and added dropwise to the reaction flask, followed by reaction at 80°C for 60 minutes under a N2 atmosphere. (5) 0.134 g / 1 mmol of trimethylolpropane (TMP) was weighed and dissolved in 5 mL of DMF solvent. After complete dissolution, the solution was added dropwise to a reaction flask and the reaction was carried out at 80°C for 60 minutes under a N2 atmosphere. (6) After the reaction was completed, the solution was poured into a polytetrafluoroethylene mold and vacuum dried at 80°C for 48 hours to remove the residual solvent. The sample was named PUD-UPy-2.

[0056] Example 4 (1) First, 3.00 g / 3 mmol of polycarbonate diol (PCDL-1000) with a molecular weight of 1000 g / mol and 1.20 g / 3 mmol of polyetheramine D400 with a molecular weight of 400 g / mol were weighed and mixed, and then placed in a three-neck flask. The mixture was stirred in an oil bath at 120°C under a N2 atmosphere for 30 minutes, and the water was removed and the mixture was dried. (2) Next, the temperature of the above mixture was cooled to 80°C, and then 30 mL of N,N-dimethylformamide (DMF) was weighed out as a solvent, and isophorone was added. J 2.20 g / 9 mmol of isocyanate (IPDI) was weighed and added dropwise to a reaction flask. 0.03 g of dibutyltin dilaurate (DBTDL) was added dropwise as a catalyst. The reaction was carried out in a N2 atmosphere for 2 h. To prevent gelation, the amount of organic solvent was appropriately adjusted to control the viscosity of the reaction mixture, yielding a prepolymer. (3) After the preparation of the prepolymer was completed, 0.38 g / 3 mmol of 2-amino-4-hydroxy-6-methylpyrimidine (UPy) was weighed out, and 3.8 ml of a DMF solution (concentration: 0.01 g / ml) was measured and added dropwise to the reaction flask. The mixture was reacted at 80°C for 60 minutes under a N2 atmosphere. (4) 0.146 g / 1 mmol of tris(2-aminoethyl)amine (TAN) was weighed and dissolved in 5 mL of DMF. After complete dissolution, the solution was added dropwise to the reaction flask and the reaction was carried out at 80° C. for 60 minutes under a N 2 atmosphere. (5) After the reaction was completed, the solution was poured into a polytetrafluoroethylene mold and vacuum dried at 80°C for 48 hours to remove the residual solvent. The sample was named PCDL-1000-UPy-TAN.

[0057] Example 5 (1) First, 6.00 g / 3 mmol of polycaprolactone diol (PCL-2000) with a molecular weight of 2000 g / mol and 1.20 g / 3 mmol of polyetheramine D400 with a molecular weight of 400 g / mol were weighed and mixed, and then placed in a three-neck flask. The mixture was stirred in an oil bath at 120°C under a N2 atmosphere for 30 minutes, and the mixture was dried to remove water. (2) Next, after the temperature of the above mixture was cooled to 80°C, 30 mL of N,N-dimethylformamide (DMF) was weighed out as a solvent, and 2.20 g / 9 mmol of hexamethylene diisocyanate (HDI) was weighed and added dropwise to a reaction flask. 0.03 g of dibutyltin dilaurate (DBTDL) was added dropwise as a catalyst, and the mixture was reacted for 2 hours in a N2 atmosphere. To prevent gelation, the amount of organic solvent was appropriately adjusted to control the viscosity of the reactant, and a prepolymer was obtained. (3) After the preparation of the prepolymer was completed, 0.38 g / 3 mmol of 2-amino-4-hydroxy-6-methylpyrimidine (UPy) was weighed out, and 3.8 ml of a DMF solution (concentration: 0.01 g / ml) was measured and added dropwise to the reaction flask. The mixture was reacted at 80°C for 60 minutes under a N2 atmosphere. (4) 0.12 g / 1 mmol of trimethylolethane (TME) was weighed and dissolved in 5 ml of DMF solvent. After complete dissolution, the solution was added dropwise to the reaction flask and the reaction was carried out at 80°C for 60 minutes under a N2 atmosphere. (5) After the reaction was completed, the solution was poured into a polytetrafluoroethylene mold and vacuum dried at 80°C for 48 hours to remove the residual solvent. The sample was named PCL-2000-UPy-TME.

[0058] Test results: In order to effectively evaluate the mechanical properties of the prepared polyurethane materials, taking Example 1 as an example, stress-strain curve tests were performed on the samples prepared in Examples 1 to 3, and the results are shown in Figures 2 and 3 and summarized in Table 1. The data in Figure 2 and Table 1 show that PUD-UPy exhibits very high tensile properties and excellent tensile strength, with a maximum tensile strength of 35.26 MPa, a breaking strain of 957%, and a toughness of 159.65 MJ / m 3 The maximum tensile strength of PUD-UPy-1 was 52.17 MPa, the fracture strain was 445%, and the toughness was 101.55 MJ / m 3 , the ultimate tensile strength of PUD-UPy-2 is 69.11 MPa, the fracture strain is 685%, and the toughness value is 198.36 MJ / m 3 It was.

[0059] Through rational molecular design and controlled distribution of soft and hard segments, PUD-UPy, PUD-UPy-1, and PUD-UPy-2 polyurethane materials all exhibit exceptional mechanical properties, namely, high mechanical strength, high tensile strength, and high toughness, which are among the highest in the polyurethane field. The content of ureidopyrimidinone groups containing quadruple hydrogen bonds significantly affects the polymer's mechanical properties, and due to effective energy dissipation, non-covalent polyurethanes exhibit significant mechanical toughness enhancement under external force. Furthermore, a triol / triamine-containing crosslinking agent in the polymer chain is used to build a strong, covalently crosslinked polyurethane network, imparting extremely high tensile strength and high modulus to the material.

[0060] Stress-strain curve of the sample:

[0061] Test standard: GB / T 1040-2006

[0062] Test speed: 100mm / min, Test environment: 25℃

[0063] Table 1. Breaking elongation, ultimate tensile strength and toughness data for Examples 1 to 3 JPEG0007733081000001.jpg46132

[0064] The stress-strain curves of sample PUD-UPy at different tensile speeds are shown in FIG. 3, which shows that the PUD-UPy prepared in this Example 1 has good stress-strain properties.

[0065] Test standard: GB / T 1040-2006

[0066] Test speed: 10mm / min to 100mm / min, Test environment: 25℃

[0067] The mechanical properties of sample PUD-UPy at different tensile speeds are summarized in Table 2.

[0068] Toughness of a material: The area under the stress-strain curve, i.e., the amount of energy absorbed by a material per unit volume before fracture occurs.

[0069] Table 2. Breaking elongation, ultimate tensile strength and toughness of PUD-UPy prepared in Example 1 JPEG0007733081000002.jpg36126

[0070] To further analyze the mechanism of reinforcement and toughness improvement of the polyurethane elastomers prepared according to the present invention, mechanical property tests were also conducted at different tensile speeds. From the results in Figure 3 and Table 2, it was found that sample PUD-UPy exhibited slightly different mechanical properties at different tensile speeds. The tensile behavior related to the deformation rate further demonstrates the dynamic properties of the chain. That is, sample PUD-UPy exhibited clear rate dependence, with a tendency for the yield and tensile strengths to increase significantly and the elongation at break to decrease as the deformation rate increased.

[0071] At low strains (10 and 50 mm / min), the materials exhibited low tensile strength and high elongation to break. At high strains (100 mm / min), the tensile strength of the materials increased significantly, while the elongation to break decreased. This was mainly due to the presence of reversible noncovalent interactions in the polymer network structure, i.e., the introduction of ureidopyrimidone units containing quadruple hydrogen-bonding groups. The deformation rate is closely related to the breaking and restructuring of the quadruple hydrogen bonds. At high strains, the reversible multiple hydrogen bonds are difficult to assemble quickly, suppressing energy dissipation and resulting in a decrease in elongation to break. At low strains, a slow tensile rate provides an opportunity for the breaking and restructuring of multiple hydrogen bonds in the polymer chains, helping to achieve effective and sufficient energy dissipation, thereby imparting a high elongation to break to the materials and effectively adjusting the mechanical properties of polyurethane, demonstrating significant mechanical strengthening and toughness enhancement under external force.

[0072] Example 1 was tested for thermal stability.

[0073] Test atmosphere: nitrogen, test temperature range: room temperature to 800°C.

[0074] The heat loss curve of sample PUD-UPy is shown in Figure 4. From Figure 4, it can be seen that PUD-UPy exhibits excellent heat resistance. The sample exhibited two decomposition temperature ranges: the hard segment decomposed at 240-350°C, and the soft segment decomposed at 350-450°C. The heat loss temperature (Td, the temperature corresponding to a 5% weight loss of the sample) of the sample was approximately 273°C. Therefore, the thermogravimetric analysis (TGA) results fully demonstrated that the polyurethane elastomer prepared according to the present invention not only exhibits high strength and high toughness, but also has excellent heat resistance.

[0075] In this invention, through rational molecular design and controlled distribution of soft and hard segments, PUD-UPy polyurethane materials exhibit exceptional mechanical properties, namely, high mechanical strength, high tensile properties, and high toughness. The content of ureidopyrimidinone groups containing quadruple hydrogen bonds significantly affects the polymer's mechanical properties, and due to effective energy dissipation, non-covalent polyurethanes exhibit significant mechanical toughness enhancement under external force. Furthermore, a triol / triamine-containing crosslinking agent in the polymer chain is used to build a strong covalently crosslinked polyurethane network, imparting extremely high tensile strength and high modulus to the material.

[0076] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any way. However, those skilled in the art can make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection.

Claims

1. 1. A method for preparing a telechelic polyurethane, comprising: A step of mixing a polyester polyol, a diisocyanate, a catalyst, and an organic solvent to carry out a prepolymerization reaction to obtain a polyurethane prepolymer; mixing a polyurethane prepolymer, a diamine chain extender, 2-amino-4-hydroxy-6-methylpyrimidine, and an organic solvent to carry out a first addition reaction to obtain an addition product; and mixing the addition product, a crosslinker, and an organic solvent to carry out a second addition reaction to obtain the telechelic polyurethane.

2. 2. The method of claim 1, wherein the diisocyanate comprises one or more of hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

3. 2. The method according to claim 1, wherein the crosslinking agent is a triol-based crosslinking agent or a triamine-based crosslinking agent, the triol-based crosslinking agent comprising at least one of trimethylolpropane, trimethylolethane and glycerin, and the triamine-based crosslinking agent comprising tris(2-aminoethyl)amine.

4. 2. The method according to claim 1, wherein the diamine chain extender is 4,4'-diaminodicyclohexylmethane or adipic acid dihydrazide.

5. A telechelic polyurethane prepared by the method according to any one of claims 1 to 4.

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