A polyurethane polymer, its preparation method and application

Abstract

The present invention discloses a polyurethane polymer, a preparation method thereof and an application thereof, relating to the technical field of polyurethane materials. The general structural formula of the polyurethane polymer is: #imgabs0#; wherein, x and y are positive integers, and x > 1, y > 1; R is R1 or R2; the structural formulas of R1 and R2 are as follows: #imgabs1#; #imgabs2#. The polyurethane polymer of the present invention simultaneously has a flexible alicyclic six-atom and an aromatic benzene ring structure, achieving a significant improvement in tensile strength and toughness. The tensile strength reaches 90.4 MPa, and the toughness is 275.5 MJ / m 3 , showing excellent mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane materials, and in particular to a polyurethane polymer, a preparation method thereof, and an application thereof. Background Art

[0002] As an important class of polymer materials, polyurethanes have received extensive attention due to their excellent mechanical properties, processability, and biocompatibility. However, there is often a trade-off between strength and toughness, which limits the development of high-performance applications. Therefore, achieving a balance between high strength and high toughness has become an important challenge in materials science. In recent years, researchers have provided effective strategies for optimizing the properties of polyurethanes by introducing hydrogen bonds and π-π interactions. However, how to precisely regulate these non-covalent interactions at the molecular level to further optimize the comprehensive properties of polyurethanes remains the core issue of current research. Therefore, the development of high-strength and high-toughness polyurethane materials will become an important direction for future research. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a polyurethane polymer. The tensile strength of this polyurethane polymer can reach 90.4 MPa, and the toughness is 275.5 MJ / m 3 , showing excellent mechanical properties.

[0004] The further technical problem to be solved by the present invention is to provide a preparation method and an application of the above polyurethane polymer.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A polyurethane polymer, the structural general formula of the polyurethane polymer is:

[0007] ;

[0008] x and y are positive integers, and x > 1, y > 1; R is R1 or R2; the structural formulas of R1 or R2 are as follows:

[0009] ;

[0010] .

[0011] Wherein, x and y can be any positive integers greater than 1. Preferably, the values of x and y are equal.

[0012] More preferably, x ranges from 1 to 13, and y ranges from 1 to 13. Preferably, x ranges from 1 to 13, and y ranges from 7 to 13.

[0013] The preparation method of the above polyurethane polymer includes the following steps:

[0014] Mix the polyurethane prepolymer, the first chain extender, and the organic solvent to conduct the first chain extension reaction to obtain a chain-extended product; the temperature of the first chain extension reaction is 60°C to 100°C, and the time is 1h to 3h; in this step, the ratio of the first chain extender to the organic solvent is 1:10 to 1:150 g / mL; more preferably, in this step, the ratio of the first chain extender to the organic solvent is 1:35 to 1:135 g / mL;

[0015] Mix the chain-extended product, the second chain extender, and the organic solvent to conduct the second chain extension reaction to obtain the polyurethane polymer; the temperature of the second chain extension reaction is 60°C to 100°C, and the time is 1h to 3h; in this step, the ratio of the second chain extender to the organic solvent is 1:10 to 1:150 g / mL; more preferably, in this step, the ratio of the second chain extender to the organic solvent is 1:40 to 1:130 g / mL;

[0016] Among them, the first chain extender is a mixture of one or more of alicyclic diol chain extenders and diamine chain extenders; the second chain extender is a mixture of one or more of aromatic diol chain extenders and diamine chain extenders;

[0017] Or the first chain extender is a mixture of one or more of aromatic diol chain extenders and diamine chain extenders; the second chain extender is a mixture of one or more of alicyclic diol chain extenders and diamine chain extenders.

[0018] Among them, the first chain extender is one or more of cis-cyclohexane-1,4-diol, 1-methylcyclohexane-1,4-diol, 4,4'-diaminodicyclohexylmethane, 1,2-diaminocyclohexane, isophorone diamine, 1,4-cyclohexanediamine.

[0019] Among them, the second chain extender is one or more of 4,4'-biphenol, hydroquinone dihydroxyethyl ether, 4,4'-diaminobenzanilide, 4,4'-diaminobenzyl, 4,4'-diaminobenzophenone, benzidine, p-phenylenediamine, 1,4-benzenedimethanamine.

[0020] Among them, the addition amounts of the first chain extender and the second chain extender determine the mechanical properties of the polyurethane polymer, and its mechanical properties can be adjusted by adjusting the addition amounts of the first chain extender and the second chain extender. Preferably, the total molar amount of the first chain extender and the second chain extender is the same as the molar amount of the polyol in the polyurethane prepolymer.

[0021] Among them, the molar ratio of the first chain extender to the second chain extender is 1:1, so that the balance of strength and toughness can be achieved.

[0022] Among them, the first chain extension reaction is carried out in a protective atmosphere; the second chain extension reaction is carried out in a protective atmosphere.

[0023] Among them, the polyurethane prepolymer is prepared by the following method:

[0024] Mix polyether or polyester polyol and organic solvent to obtain a mixed solution; specifically, place the polyester polyol into a reaction vessel, stir under an oil bath condition of 100-150°C and an inert gas atmosphere to remove water and dry; then add an organic solvent as a reaction solvent to the reaction vessel and stir evenly to obtain a mixed solution; the ratio of polyester polyol to organic solvent is 1:20-1:1 g / mL; preferably, the ratio of polyester polyol to organic solvent is 1:1-1:3 g / mL;

[0025] Mix the mixed solution, diisocyanate, catalyst and organic solvent to carry out a prepolymerization reaction to obtain a polyurethane prepolymer; the ratio of diisocyanate to the added organic solvent is 1:20-1:1 g / mL; the mass ratio of the diisocyanate to the catalyst is 120:1-230:1; preferably, in this step, the ratio of diisocyanate to the added organic solvent is 1:5-1:10 g / mL;

[0026] Among them, the molar ratio of the polyether or polyester polyol to the diisocyanate is 1:2 to 1:2.4; the temperature of the prepolymerization reaction is 60°C-100°C, and the reaction time is 2h-5h.

[0027] Among them, the diisocyanate is one or more of toluene-2,4-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate; preferably, the diisocyanate is a cycloaliphatic diisocyanate, preferably isophorone diisocyanate or 4,4'-dicyclohexylmethane diisocyanate.

[0028] The catalyst is one or more of amine catalysts and organometallic catalysts.

[0029] The organic solvent is preferably one or more of N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran and N-methylpyrrolidone.

[0030] The average molecular weight of the polyol is 1000-3000, and the polyol is preferably one or more of polyether or polyester polyol.

[0031] The above-mentioned polyurethane polymer is applied in intelligent manufacturing, aerospace and flexible electronics.

[0032] The beneficial effects of the present invention are as follows:

[0033] (1) The polyurethane polymer of the present invention simultaneously has a flexible alicyclic six-atom and an aromatic benzene ring structure, achieving a significant improvement in tensile strength and toughness. The tensile strength reaches 90.4 MPa and the toughness is 275.5 MJ / m 3 , showing excellent mechanical properties.

[0034] (2) The polyurethane polymer of the present invention has excellent film-forming properties and heat resistance.

[0035] (3) The present invention adopts a two-step chain extension reaction, which can achieve an ordered chain segment arrangement to form a block structure. This block structure is an orderedness-optimizable material with a microphase separation structure (distribution of hard segment microdomains and soft segment microdomains), thereby improving mechanical properties and stability. Description of the Drawings

[0036] Figure 1 It is the infrared spectrogram of Examples 1 to 3 and Comparative Examples 1 and 2 of the present invention.

[0037] Figure 2 It is the infrared spectrogram of Examples 4 to 6 and Comparative Examples 3 and 4 of the present invention.

[0038] Figure 3 It is the atomic force microscope (AFM) image of Comparative Example 1.

[0039] Figure 4 It is the atomic force microscope (AFM) image of Comparative Example 2.

[0040] Figure 5 It is the atomic force microscope (AFM) image of Example 1.

[0041] Figure 6 It is the atomic force microscope (AFM) image of Example 2.

[0042] Figure 7 It is the atomic force microscope (AFM) image of Example 3.

[0043] Figure 8 It is the atomic force microscope (AFM) image of Comparative Example 3.

[0044] Figure 9 It is the atomic force microscope (AFM) image of Comparative Example 4.

[0045] Figure 10 It is the atomic force microscope (AFM) image of Example 4.

[0046] Figure 11 It is the atomic force microscope (AFM) image of Example 5.

[0047] Figure 12It is the atomic force microscope (AFM) image of Example 6.

[0048] Figure 13 It is the thermogravimetric analysis curve of Example 2.

[0049] Figure 14 It is the stress-strain curve of Examples 1 to 3 and Comparative Examples 1 and 2 of the present invention.

[0050] Figure 15 It is the stress-strain curve of Examples 4 to 6 and Comparative Examples 3 and 4 of the present invention.

[0051] Figure 16 It is the nuclear magnetic resonance hydrogen spectrum of Example 2 of the present invention. Detailed implementation mode

[0052] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0053] Unless otherwise specified, the reagents used in the following examples are all commercially available.

[0054] The preparation method of the polyurethane polymer of the present invention is as follows:

[0055] I. Preparation of polyurethane prepolymer (prepolymerization reaction):

[0056] First, select appropriate polyether or polyester polyol (molecular weight range: 1000 - 3000), mix them, place them in a three-necked flask, and under the condition of an oil bath at 100°C - 150°C, introduce nitrogen and stir (30 min - 120 min) to fully remove moisture and other impurities;

[0057] After the temperature of the liquid to be mixed is cooled to 60 °C to 100 °C, an equivalent amount of diisocyanate (the diisocyanate can be: one or more of toluene-2,4-diisocyanate (2,4-TDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI)) is added, and a certain amount of organic solvent (solvents that can be selected: one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), tetrahydrofuran, and N-methylpyrrolidone (NMP)) is measured. The two are mixed and dropped into the reaction flask, and a small amount of catalyst is dropped (the catalysts that can be selected are: amine catalysts and organometallic catalysts. Amine catalysts such as: triethylamine, N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine, etc.; organometallic catalysts such as: dibutyltin dilaurate, stannous octoate, zinc octoate, etc.). The reaction is carried out in an N2 atmosphere for 2 h to 5 h to obtain a polyurethane prepolymer.

[0058] II. First chain extension reaction:

[0059] After the prepolymer is prepared, a first chain extension reaction is carried out to obtain a chain-extended product. The first chain extension reaction uses a mixture of one or more of aromatic diol chain extenders and diamine chain extenders, or a mixture of one or more of alicyclic diol chain extenders and diamine chain extenders.

[0060] Specifically, a certain amount of the same organic solvent is measured and added to the prepolymer, and then added to the reaction flask. The reaction is carried out in an N2 atmosphere, the reaction temperature is 60 °C to 100 °C, and the reaction time is 1 h to 3 h to obtain a chain-extended product.

[0061] III. Second chain extension reaction:

[0062] A second chain extender is added to the chain-extended product for the second chain extension reaction. The second chain extender is a chain extender of a different type from the first chain extender. Specifically, if the first chain extender is an aromatic chain extender, the second chain extender is an alicyclic chain extender; if the first chain extender is an alicyclic chain extender, the second is an aromatic chain extender.

[0063] Specifically, the chain-extended product, the second chain extender, and the organic solvent are mixed for the second chain extension reaction to obtain the polyurethane polymer; the temperature of the second chain extension reaction is 60 °C to 100 °C, and the time is 1 h to 3 h.

[0064] IV. After the reaction is completed, the solution is poured into a polytetrafluoroethylene mold and vacuum-dried at 60 °C to 120 °C for 24 h to 72 h to remove the residual solvent, obtaining a polyurethane elastomer film.

[0065] The polyurethane polymer prepared by the present invention uses a flexible alicyclic six-atom structure to replace the rigid aromatic spacer, and two chain extenders are added step by step. Compared with adding the two chain extenders simultaneously, it has the following remarkable advantages:

[0066] (1) Ordered chain segment arrangement: The stepwise reaction allows one chain extender to be introduced first to react with the prepolymer to form specific chain segments, and then extended by the second chain extender to achieve a block structure. This order can optimize the microphase separation of the material (such as the distribution of hard segment microdomains and soft segment microdomains), thereby improving the mechanical properties (such as tensile strength and toughness) and thermal stability.

[0067] (2) Reduction of by-product generation: Adding the two chain extenders simultaneously may trigger competitive reactions, resulting in by-products, while adding them step by step can effectively reduce such problems.

[0068] (3) Avoidance of gelation risk: Adding the two chain extenders simultaneously may lead to local gelation, and adding them step by step can reduce the risk of process out-of-control.

[0069] Preferably, the first chain extender is one or a mixture of one or more of alicyclic diol chain extenders and diamine chain extenders, and the second chain extender is one or a mixture of one or more of aromatic diol chain extenders and diamine chain extenders.

[0070] Using one or a mixture of one or more of alicyclic diol chain extenders and diamine chain extenders as the chain extender; (optional: diol chain extenders: cis-cyclohexane-1,4-diol, 1-methylcyclohexane-1,4-diol; diamine chain extenders: one or more of 4,4'-diaminodicyclohexylmethane, 1,2-diaminocyclohexane, isophorone diamine, 1,4-cyclohexanediamine), the reaction structural formula is shown as follows:

[0071] ;

[0072] or

[0073] .

[0074] One or a mixture of one or more of aromatic diol chain extenders and diamine chain extenders; specifically, 4,4'-biphenol, hydroquinone diethyl ether, 4,4'-diaminobenzanilide, 4,4'-diaminobenzyl, 4,4'-diaminobenzophenone, benzidine, p-phenylenediamine, 1,4-benzenedimethanamine, etc. can be selected. If the chain extender is solid, it needs to be dissolved in an organic solvent and ultrasonically treated to completely dissolve it before dropping it into the reaction flask.

[0075] Aiming at the inherent contradiction between strength and toughness in traditional polyurethane materials, through a molecular engineering strategy, the present invention designs a new type of polyurethane elastomer synergistically strengthened by a dynamic hydrogen bond network (a three-dimensional network structure formed by intermolecular or intramolecular hydrogen bonding between urethane (-NHCOO-) and urea (-NH-COO-NH-) groups in the structural formula) and a flexible alicyclic six-atom structure, breaking through the trade-off limit of mechanical properties and providing an innovative solution for the development of high-performance structural materials.

[0076] The present invention has achieved significant improvements in tensile strength and toughness. The tensile strength reaches 90.4 MPa and the toughness is 275.5 MJ / m 3 , showing excellent mechanical properties. To achieve this goal, a flexible alicyclic six-atom structure is used to replace the rigid aromatic spacer, promoting the close packing of molecular chains while retaining the dynamic movement ability of chain segments and avoiding brittle fracture. At the same time, the strong dipole interaction formed by urea groups (-NH-COO-NH-) in the material effectively dissipates energy under external force through the breaking and recombination mechanism of dynamic hydrogen bonds, enhancing strength and toughness. In addition, the polarity difference between the hard segment and the soft segment drives the formation of nanoscale microdomains, thereby optimizing the microphase separation structure and further improving the interfacial stress transfer efficiency.

[0077] The present invention solves the long-term contradiction between strength and toughness of polyurethane materials by precisely regulating non-covalent interactions at the molecular scale. Moreover, the polyurethane material prepared by the present invention has adjustable mechanical properties, including high strength, high toughness, excellent stretchability, as well as excellent film-forming properties and heat resistance. This provides a new idea for the molecular design of high-performance polymer materials and has significant industrial application potential.

[0078] Example 1

[0079] (1) First, weigh 10 mmol (20.0 g with a molecular weight of 2000 g / mol) of polycarbonate diol (PCDL-2000) and 25 mL of N,N-dimethylformamide (DMF), mix them and place them in a three-necked flask. Stir for 60 min under the conditions of an oil bath at 120 °C and an N2 atmosphere to fully remove moisture and other impurities.

[0080] (2) Next, after the temperature of the above-mentioned mixed solution is cooled to 80 °C, 20 mmol (4.45 g) of IPDI (isophorone diisocyanate, molecular weight 222.29 g / mol) is weighed, 25 mL of N,N-dimethylformamide (DMF) is measured as an organic solvent, and after mixing, it is added to a three-necked flask. Then, 0.02 g of dibutyltin dilaurate (DBTDL) is added as a catalyst. The prepolymerization reaction is stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 3 h to obtain an isocyanate-terminated polyurethane prepolymer.

[0081] (3) After the prepolymerization reaction is completed, 2.5 mmol (0.53 g) of 4,4'-diaminodicyclohexylmethane (DDM) is weighed, and 62 mL of DMF solvent is measured. The two are mixed and ultrasonicated until completely dissolved, and then added to the three-necked flask. The reaction is stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 60 min.

[0082] (4) Next, 7.5 mmol (0.92 g) of the chain extender in solid form: benzidine (BZ) is weighed, and 38 mL of DMF solvent is measured. The two are mixed and ultrasonicated until completely dissolved, and then added to the three-necked flask. The reaction is stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 60 min.

[0083] (5) After the reaction is completed, the solution is poured into a polytetrafluoroethylene mold and vacuum-dried at 80 °C for 48 h to remove the residual solvent. The sample is named Example 1.

[0084] Example 2

[0085] The specific steps are the same as those in Example 1, except that the dosage of the first chain extender 4,4'-diaminodicyclohexylmethane (DDM) is 5 mmol, and the dosage of the second chain extender benzidine (BZ) is 5 mmol. The sample is named Example 2.

[0086] Example 3

[0087] The specific steps are the same as those in Example 1, except that the dosage of the first chain extender 4,4'-diaminodicyclohexylmethane (DDM) is 7.5 mmol, and the dosage of the second chain extender benzidine (BZ) is 2.5 mmol. The sample is named Example 3.

[0088] Comparative Example 1

[0089] (1) First, weigh 10 mmol (20.0 g with a molecular weight of 2000 g / mol) of polycarbonate diol (PCDL-2000) and 25 mL of N,N-dimethylformamide (DMF), mix them in a three-necked flask, and stir for 60 min under an oil bath condition of 120 °C and in an N2 atmosphere to fully remove moisture and other impurities.

[0090] (2) Next, after the temperature of the above mixture is cooled to 80 °C, weigh 20 mmol (4.45 g) of IPDI (isophorone diisocyanate, with a molecular weight of 222.29 g / mol), measure 25 mL of N,N-dimethylformamide (DMF) as an organic solvent, mix them and add them to the three-necked flask, and add 0.02 g of dibutyltin dilaurate (DBTDL) as a catalyst. The prepolymerization reaction is stirred under an oil bath condition of 80 °C and in an N2 atmosphere for 3 h to obtain an isocyanate-terminated polyurethane prepolymer.

[0091] (3) After the prepolymerization reaction is completed, weigh 10 mmol (1.84 g) of the chain extender: benzidine (BZ) in solid form, measure 50 mL of DMF solvent, mix them, ultrasonically treat until completely dissolved, add them to the three-necked flask, and the reaction is stirred under an oil bath condition of 80 °C and in an N2 atmosphere for 60 min.

[0092] (4) After the reaction is completed, pour the solution into a polytetrafluoroethylene mold, and under vacuum and dry at 80 °C for 48 h to remove the residual solvent, and it is named Comparative Example 1.

[0093] Comparative Example 2

[0094] (1) First, weigh 10 mmol, 20.0 g with a molecular weight of 2000 g / mol of polycarbonate diol (PCDL-2000) and 25 mL of N,N-dimethylformamide (DMF), mix them in a three-necked flask, and stir for 60 min under an oil bath condition of 120 °C and in an N2 atmosphere to fully remove moisture and other impurities.

[0095] (2) Next, after the temperature of the above mixture is cooled to 80 °C, weigh 20 mmol, 4.45 g of IPDI (isophorone diisocyanate, with a molecular weight of 222.29 g / mol), measure 25 mL of N,N-dimethylformamide (DMF) as an organic solvent, mix them and add them to the three-necked flask, and add 0.02 g of dibutyltin dilaurate (DBTDL) as a catalyst. The prepolymerization reaction is stirred under an oil bath condition of 80 °C and in an N2 atmosphere for 3 h to obtain an isocyanate-terminated polyurethane prepolymer.

[0096] After the prepolymerization reaction was completed, 10 mmol (2.1 g) of the chain extender 4,4'-diaminodicyclohexylmethane was weighed, and 50 mL of DMF solvent was measured. The two were mixed and ultrasonically treated until completely dissolved, and then added to a three-necked flask. The reaction was stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 60 min.

[0097] After the reaction ended, the solution was poured into a polytetrafluoroethylene mold and vacuum-dried at 80 °C for 48 h to remove the residual solvent, and it was named Comparative Example 2.

[0098] Example 4

[0099] First, 10 mmol (20.0 g with a molecular weight of 2000 g / mol) of polycarbonate diol (PCDL-2000) and 25 mL of N,N-dimethylformamide (DMF) were weighed and mixed in a three-necked flask. The mixture was stirred under an oil bath condition at 120 °C and in an N2 atmosphere for 60 min to fully remove moisture and other impurities.

[0100] Next, after the temperature of the above mixture was cooled to 80 °C, 20 mmol (3.48 g) of 2,4-TDI (toluene-2,4-diisocyanate, with a molecular weight of 174.16 g / mol) was weighed, and 25 mL of N,N-dimethylformamide (DMF) was measured as an organic solvent. After mixing, it was added to the three-necked flask, and 0.02 g of dibutyltin dilaurate (DBTDL) was added as a catalyst. The prepolymerization reaction was stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 3 h to obtain an isocyanate-terminated polyurethane prepolymer.

[0101] After the prepolymerization reaction was completed, 2.5 mmol (0.53 g) of 4,4'-diaminodicyclohexylmethane (DDM) was weighed, and 62 mL of DMF solvent was measured. The two were mixed and ultrasonically treated until completely dissolved, and then added to the three-necked flask. The reaction was stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 60 min.

[0102] Next, 7.5 mmol (0.92 g) of the solid chain extender: benzidine (BZ) was weighed, and 38 mL of DMF solvent was measured. The two were mixed and ultrasonically treated until completely dissolved, and then added to the three-necked flask. The reaction was stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 60 min.

[0103] After the reaction ended, the solution was poured into a polytetrafluoroethylene mold and vacuum-dried at 80 °C for 48 h to remove the residual solvent, and it was named Example 4.

[0104] Example 5

[0105] The specific steps are the same as those in Example 4, except that the dosage of the first chain extender 4,4'-diaminodicyclohexylmethane (DDM) is 5 mmol, and the dosage of the second chain extender benzidine (BZ) is 5 mmol. The sample was named Example 5.

[0106] Example 6

[0107] The specific steps are the same as those in Example 4, except that the dosage of the first chain extender 4,4'-diaminodicyclohexylmethane (DDM) is 7.5 mmol, and the dosage of the second chain extender benzidine (BZ) is 2.5 mmol. The sample was named Example 6.

[0108] Comparative Example 3

[0109] (1) First, weigh 10 mmol (20.0 g with a molecular weight of 2000 g / mol) of polycarbonate diol (PCDL-2000) and 25 mL of N,N-dimethylformamide (DMF), mix them and place them in a three-necked flask. Stir for 60 min under the conditions of an oil bath at 120 °C and an N2 atmosphere to fully remove moisture and other impurities.

[0110] (2) Then, after the temperature of the above mixture is cooled to 80 °C, weigh 20 mmol (3.48 g) of 2,4-TDI (toluene-2,4-diisocyanate, with a molecular weight of 174.16 g / mol), measure 25 mL of N,N-dimethylformamide (DMF) as an organic solvent, mix them and add them to the three-necked flask, and add 0.02 g of dibutyltin dilaurate (DBTDL) as a catalyst. The prepolymerization reaction is stirred under the conditions of an oil bath at 80 °C and an N2 atmosphere for 3 h to obtain an isocyanate-terminated polyurethane prepolymer.

[0111] (3) After the prepolymerization reaction is completed, weigh 10 mmol (1.84 g) of the solid chain extender: benzidine (BZ), measure 50 mL of DMF solvent, mix them, ultrasonically treat until completely dissolved, and add them to the three-necked flask. The reaction is stirred under the conditions of an oil bath at 80 °C and an N2 atmosphere for 60 min.

[0112] (4) After the reaction is completed, pour the solution into a polytetrafluoroethylene mold, and under vacuum and dry at 80 °C for 48 h to remove the residual solvent, and it was named Comparative Example 3.

[0113] Comparative Example 4

[0114] (1) First, weigh 10 mmol, 20.0 g of polycarbonate diol (PCDL-2000) with a molecular weight of 2000 g / mol and 25 mL of N,N-dimethylformamide (DMF), mix them and place them in a three-necked flask. Stir for 60 min under the conditions of an oil bath at 120 °C and an N2 atmosphere to fully remove moisture and other impurities.

[0115] (2) Next, after the temperature of the above mixture is cooled to 80 °C, weigh 20 mmol (3.48 g) of 2,4-TDI (toluene-2,4-diisocyanate, molecular weight 174.16 g / mol), measure 25 mL of N,N-dimethylformamide (DMF) as an organic solvent, mix them and add them to the three-necked flask. Then add 0.02 g of dibutyltin dilaurate (DBTDL) as a catalyst. The prepolymerization reaction is stirred under the conditions of an oil bath at 80 °C and an N2 atmosphere for 3 h to obtain an isocyanate-terminated polyurethane prepolymer.

[0116] (3) After the prepolymerization reaction is completed, weigh 10 mmol, 2.1 g of chain extender 4,4'-diaminodicyclohexylmethane, measure 50 mL of DMF solvent, mix them, ultrasonically treat until completely dissolved, and add them to the three-necked flask. The reaction is stirred under the conditions of an oil bath at 80 °C and an N2 atmosphere for 60 min.

[0117] (4) After the reaction is completed, pour the solution into a polytetrafluoroethylene mold, and carry out vacuum and drying treatment at 80 °C for 48 h to remove the residual solvent, and it is named Comparative Example 4.

[0118] Example 7

[0119] (1) First, weigh 10 mmol (20.0 g of polycarbonate diol (PCDL-2000) with a molecular weight of 2000 g / mol) and 30 mL of N,N-dimethylformamide (DMF), mix them and place them in a three-necked flask. Stir for 60 min under the conditions of an oil bath at 120 °C and an N2 atmosphere to fully remove moisture and other impurities.

[0120] (2) Next, after the temperature of the above mixture is cooled to 80 °C, weigh 24 mmol (6.3 g) of 4,4'-dicyclohexylmethane diisocyanate (molecular weight 262.35 g / mol), measure 60 mL of N,N-dimethylformamide (DMF) as an organic solvent, mix them and add them to the three-necked flask. Then add 0.03 g of dibutyltin dilaurate (DBTDL) as a catalyst. The prepolymerization reaction is stirred under the conditions of an oil bath at 80 °C and an N2 atmosphere for 3 h to obtain an isocyanate-terminated polyurethane prepolymer.

[0121] After the prepolymerization reaction was completed, 6 mmol (0.78 g) of 1-methylcyclohexane-1,4-diol was weighed, and 62 mL of DMF solvent was measured. The two were mixed and ultrasonically treated until completely dissolved, and then added to a three-necked flask. The reaction was stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 120 min.

[0122] (4)Subsequently, 8 mmol (1.82 g) of 4,4'-diaminobenzanilide was weighed, and 38 mL of DMF solvent was measured. The two were mixed and ultrasonically treated until completely dissolved, and then added to a three-necked flask. The reaction was stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 60 min.

[0123] (5)After the reaction was completed, the solution was poured into a polytetrafluoroethylene mold and vacuum-dried at 80 °C for 48 h to remove the residual solvent, and then the polyurethane polymer could be obtained.

[0124] Example 8

[0125] (1)First, 10 mmol (20.0 g with a molecular weight of 2000 g / mol) of polycarbonate diol (PCDL-2000) and 60 mL of N,N-dimethylformamide (DMF) were weighed and mixed and placed in a three-necked flask. The mixture was stirred under an oil bath condition at 120 °C and in an N2 atmosphere for 60 min to fully remove moisture and other impurities.

[0126] (2)Subsequently, after the temperature of the above mixture was cooled to 80 °C, 22 mmol (5.77 g) of 4,4'-dicyclohexylmethane diisocyanate was weighed, and 50 mL of N,N-dimethylformamide (DMF) was measured as an organic solvent. The two were mixed and then added to the three-necked flask, and 0.03 g of dibutyltin dilaurate (DBTDL) was added as a catalyst. The prepolymerization reaction was stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 3 h to obtain an isocyanate-terminated polyurethane prepolymer.

[0127] (3)After the prepolymerization reaction was completed, 5 mmol (0.54 g) of p-phenylenediamine was weighed, and 38 mL of DMF solvent was measured. The two were mixed and ultrasonically treated until completely dissolved, and then added to a three-necked flask. The reaction was stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 60 min.

[0128] (4)Subsequently, 4 mmol (0.46 g) of 1,4-cyclohexanediamine was weighed, and 62 mL of DMF solvent was measured. The two were mixed and ultrasonically treated until completely dissolved, and then added to a three-necked flask. The reaction was stirred under an oil bath condition at 80 °C and in an N2 atmosphere for 60 min.

[0129] (5) After the reaction is completed, the solution is poured into a polytetrafluoroethylene mold and vacuum-dried at 80 °C for 48 h to remove the residual solvent, and the polyurethane polymer can be obtained.

[0130] Test results and analysis:

[0131] I. Characterization and analysis:

[0132] Figure 1 and Figure 2 are the Fourier transform infrared spectroscopy (FTIR) spectra of Examples 1 to 6 and Comparative Examples 1 to 4. It can be seen from the figure that a characteristic peak of the N-H group appears at 3380 cm -1 and the stretching vibration peak of the carbonyl group (-C=O-) in the urethane (-NHCOO-) group is attributed to 1738 cm -1 . The characteristic peak at 1240 cm -1 is the stretching vibration peak of the -C-O- part in the urethane (-NHCOO-) group. The characteristic peak of the -NCO group does not appear at 2260 - 2280 cm -1 , which proves the successful preparation of the polyurethane elastomer.

[0133] In addition, 1H nuclear magnetic resonance spectroscopy characterization was also carried out on Example 2. Figure 16 is the 1H nuclear magnetic resonance spectrum of Example 2 in deuterated CDCI3, and the following are the positions of each characteristic peak. 7.27 ppm is the peak position of the solvent deuterated CDCI3. The -CH group of benzidine (BZ) corresponds to two peak positions. The peak position near 4.1 ppm is that of PCDL-2000. 3.79 ppm, 2.92 ppm, and 0.93 ppm correspond to the -CH, -CH2, and -CH3 groups of isophorone diisocyanate (IPDI) respectively. The range from 1.06 ppm to 1.71 ppm is the -CH and -CH2 groups of isophorone diisocyanate (IPDI) and 4,4'-diaminodicyclohexylmethane (DDM). The positions of these peaks reflect the response of hydrogen atoms in different parts of the molecule in the magnetic field, and the above analysis also indicates its successful preparation.

[0134] The microphase structure and surface morphology of Examples 1 to 6 and Comparative Examples 1 to 4 were systematically characterized using atomic force microscopy (AFM). The microphase structure of the samples was observed by atomic force microscopy in tapping mode, and the scanning area size was 3 μm × 3 μm. See specifically Figures 3 to 7 and Figures 8 to 12 .

[0135] From Figures 3 to 7 and Figures 8 to 12It can be seen from the results shown that the AFM phase images of the six embodiments and four comparative examples all show obvious light and dark contrast areas, clearly revealing the microphase separation characteristics of the soft and hard segments in the polyurethane system: the dark area corresponds to the amorphous phase formed by polyester diol as the soft segment, while the bright area originates from the aggregation of the hard segment part constructed by isocyanate and chain extender. This microphase separation behavior is of great significance to the mechanical properties of the material: moderate microphase separation can significantly improve the strength and toughness of the material through the synergistic effect of the hard segment physical cross-linking network and the soft segment flexible matrix. Through further comparison, it was found that the boundaries of the light and dark phase regions of Example 2 were the most distinct and the degree of phase separation was the highest, while the phase region of Comparative Example 3 was the most blurred, indicating that its degree of microphase separation was relatively weak. This result is completely consistent with the mechanical test data, which fully verifies that the microphase separation behavior of polyurethane can be effectively optimized by regulating the ratio and compatibility of soft and hard segments through molecular design, thereby giving the material excellent comprehensive mechanical properties.

[0136] Through precise molecular design, we have constructed a polyurethane elastomer with high strength, high toughness and extraordinary stretchability, breaking through the trade-off between strength and toughness of traditional polymer materials. We have conducted comparative studies on polymers with similar but slightly different structures by optimizing the structure of the hard segment to achieve the desired goal of the polyurethane elastomer. The structure of the optimized hard segment in this embodiment refers to the isocyanate and the chain extender forming the hard segment together. By changing the type of isocyanate, that is, replacing the rigid aromatic interval with a more flexible alicyclic six-atom structure, the structure of the hard segment is optimized, thereby improving the overall strength and toughness of the material.

[0137] Compared with traditional aromatic spacers, the polyurethane material prepared by the present invention adopts a more flexible alicyclic six-atom spacer structure to promote close packing between molecules and enhance the density of hydrogen bonds, thereby improving the overall strength and toughness of the material. This unique molecular construction method not only improves the stability of the polymer chain, but also provides an efficient energy dissipation mechanism when subjected to force, making the strength of the polyurethane 90.4 MPa and the toughness 275.5 MJ / m 3 .

[0138] 2. Performance Analysis

[0139] 2.1 Thermal performance

[0140] In order to effectively evaluate the thermal properties of the prepared optimal material, a thermogravimetric analysis was performed on Example 2. The test atmosphere was nitrogen, and the test temperature range was 50°C to 750°C. Figure 13 This is the thermogravimetric analysis (TGA) diagram of Example 2. Figure 13 As shown in the figure, thermogravimetric analysis shows that Example 2 exhibits higher thermal stability, and the initial thermal decomposition temperature (T d, the temperature corresponding to a 5% weight loss of the sample was 283.4 °C, which was better than most polyurethane elastomers, showing good heat resistance, meeting the requirements of various practical applications, and having the potential to be applied in extreme conditions or complex environments.

[0141] 2.2 Mechanical properties

[0142] To effectively evaluate the mechanical properties of the prepared polyurethane materials, a tensile testing machine was used to conduct stress-strain tests on the elastomer films of six examples and four comparative examples. The test standard was GB / T 1040-2006, the test speed (tensile rate) was 100 mm / min, and the test environment was 25 °C. The test results such as tensile strength, elongation at break, and toughness (curve integral area) were compared, and the obtained results are shown in Figure 14 and Figure 15 as shown, and the relevant data have been summarized in Table 1.

[0143] Table 1 Ultimate tensile strength, elongation at break, and toughness of Examples 1 to 6 and Comparative Examples 1 to 4

[0144]

[0145] From Figure 14 , Figure 15 and the results in Table 1, it can be seen that the tensile strength (i.e., ultimate engineering stress) of Comparative Example 2 was 33.5 MPa, the elongation at break was 1132%, and the toughness was 121.2 MJ / m 3 ; the tensile strength (i.e., ultimate engineering stress) of Comparative Example 1 was 37.7 MPa, the elongation at break was 1114%, and the toughness was 144.2 MJ / m 3 . In contrast, the tensile strength of Example 2 was as high as 90.4 MPa, which was 2.4 to 2.7 times higher than that of Comparative Example 2 and Comparative Example 1. Example 2 still maintained a relatively high elongation at break of 972%, resulting in a toughness of 275.5 MJ / m 3 . Compared with Comparative Example 2 and Comparative Example 1, the toughness was increased by 1.91 to 2.27 times. Example 2 showed extremely high tensile strength, outstanding stretchability, and high toughness. Compared with Example 5, both its strength and toughness were significantly improved. This indicates that by using a relatively flexible alicyclic six-atom structure (IPDI) to replace the rigid aromatic spacer (TDI) to optimize the structure of the hard segment, the overall strength and toughness of the material can be effectively improved.

[0146] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0147] The parts not elaborated in detail in the specification of the present invention belong to the well-known technologies in the art. The above embodiments are provided only for the purpose of describing the present invention, rather than limiting the scope of the present invention. The scope of the present invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principle of the present invention shall be covered within the scope of the present invention.

Claims

1. A polyurethane polymer, characterized in that The general structural formula of the polyurethane polymer is: ； Wherein, x and y are positive integers, and x>1, y>1; R is R1 or R2; the structural formula of R1 or R2 is as follows: ； ； The connection mode of R and amino group depends on the type of diisocyanate, and the diisocyanate is toluene-2,4-diisocyanate or isophorone diisocyanate.

2. The polyurethane polymer according to claim 1, characterized in that The x and y values ​​are equal.

3. The polyurethane polymer according to claim 1, characterized in that x is 1 to 13, y is 1 to 13.

4. A method for preparing a polyurethane polymer according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: The polyurethane prepolymer, the first chain extender and the organic solvent are mixed to perform a first chain extension reaction to obtain a chain extension product; the temperature of the first chain extension reaction is 60° C. to 100° C., and the time is 1 h to 3 h; The chain extension product, the second chain extender and the organic solvent are mixed to carry out a second chain extension reaction to obtain the polyurethane polymer; the temperature of the second chain extension reaction is 60° C. to 100° C., and the time is 1 h to 3 h; The first chain extender is an alicyclic diamine chain extender 4,4'-diaminodicyclohexylmethane, and the second chain extender is an aromatic diamine chain extender benzidine; Or the first chain extender is an aromatic diamine chain extender, benzidine, and the second chain extender is an alicyclic diamine chain extender, 4,4'-diaminodicyclohexylmethane; The polyurethane prepolymer is prepared by the following method: mixing polycarbonate diol and an organic solvent to obtain a mixed solution; The mixed solution, diisocyanate, catalyst and organic solvent are mixed to carry out prepolymerization reaction to obtain a polyurethane prepolymer; Wherein, the molar ratio of the polycarbonate diol to the diisocyanate is 1:2 to 1:2.4; the temperature of the prepolymerization reaction is 60° C. to 100° C., and the reaction time is 2 h to 5 h; The diisocyanate is toluene-2,4-diisocyanate or isophorone diisocyanate.

5. The method for preparing a polyurethane polymer according to claim 4, characterized in that: The total mole number of the first chain extender and the second chain extender is the same as the mole number of the polyol in the polyurethane prepolymer.

6. The method for preparing a polyurethane polymer according to claim 5, characterized in that: The molar ratio of the first chain extender to the second chain extender is 1:

1.

7. The method for preparing a polyurethane polymer according to claim 4, characterized in that: The first chain extension reaction is carried out in a protective atmosphere; and the second chain extension reaction is carried out in a protective atmosphere.

8. The method for preparing a polyurethane polymer according to claim 4, characterized in that: The catalyst is one of an amine catalyst and an organic metal catalyst; The organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran and N-methylpyrrolidone.

9. Application of the polyurethane polymer according to any one of claims 1 to 3 in intelligent manufacturing, aerospace and flexible electronics.

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