CN119875067A

CN119875067A - Polyurethane polymer and preparation method and application thereof

Info

Publication number: CN119875067A
Application number: CN202510379709.5A
Authority: CN
Inventors: 张新瑞; 王重阳; 徐静; 陈天泽; 王齐华; 王廷梅; 张耀明; 裴先强
Original assignee: Lanzhou Institute of Chemical Physics LICP of CAS
Current assignee: Lanzhou Institute of Chemical Physics LICP of CAS
Priority date: 2025-03-28
Filing date: 2025-03-28
Publication date: 2025-04-25
Anticipated expiration: 2045-03-28
Also published as: CN119875067B

Abstract

The present invention discloses a polyurethane polymer and a preparation method and application thereof, and relates to the technical field of polyurethane materials. The general structural formula of the polyurethane polymer is: ; wherein x and y are positive integers, and x＞1, y＞1; R is R ₁ or R ₂ ; the structural formulas of R ₁ and R ₂ are as follows: ; The polyurethane polymer of the present invention has both a flexible alicyclic hexaatomic structure and an aromatic benzene ring structure, and achieves significant improvements in tensile strength and toughness, with a tensile strength of 90.4 MPa and a toughness of 275.5 MJ/m ³ , showing excellent mechanical properties.

Description

Polyurethane polymer and preparation method and application thereof

Technical Field

The invention relates to the technical field of polyurethane materials, in particular to a polyurethane polymer and a preparation method and application thereof.

Background

Polyurethane is an important polymer material, and is widely focused on due to its excellent mechanical properties, processability and biocompatibility. However, the strength and toughness often have contradictions between each other, limiting the development of high performance applications. Therefore, achieving a balance of high strength and high toughness is an important challenge for materials science. In recent years, researchers have provided an effective strategy for optimizing polyurethane properties by introducing hydrogen bonds and pi-pi interactions. However, how to precisely regulate these non-covalent interactions at the molecular level to further optimize the overall properties of polyurethanes remains a central issue in current research. Therefore, development of polyurethane materials with high strength and high toughness will become an important direction of future research.

Disclosure of Invention

In order to solve the technical problems, the invention provides a polyurethane polymer. The tensile strength of the polyurethane polymer can reach 90.4 MPa, the toughness is 275.5 MJ/m ³, and the polyurethane polymer has excellent mechanical properties.

The invention further aims to provide a preparation method and application of the polyurethane polymer.

In order to achieve the above purpose, the invention adopts the following technical scheme:

a polyurethane polymer having the structural formula:

;

x and y are positive integers and x >1, y >1, R is R ₁ or R ₂;R₁ or R ₂ having the formula:

;

。

Wherein x and y may be any positive integer greater than 1. Preferably, the x and y values are equal.

More preferably, x is 1 to 13 and y is 1 to 13. Preferably, x is 1 to 13 and y is 7 to 13.

The preparation method of the polyurethane polymer comprises the following steps:

Mixing polyurethane prepolymer, a first chain extender and an organic solvent for a first chain extension reaction to obtain a chain extension product, wherein the temperature of the first chain extension reaction is 60-100 ℃ and the time is 1-3 h, the ratio of the first chain extender to the organic solvent in the step is 1:10-1:150 g/mL, and more preferably, the ratio of the first chain extender to the organic solvent in the step is 1:35-1:135 g/mL;

Mixing the chain extension product, a second chain extender and an organic solvent for a second chain extension reaction to obtain the polyurethane polymer, wherein the temperature of the second chain extension reaction is 60-100 ℃ and the time is 1-3 h, the ratio of the second chain extender to the organic solvent in the step is 1:10-1:150 g/mL, and more preferably, the ratio of the second chain extender to the organic solvent in the step is 1:40-1:130 g/mL;

the first chain extender is a mixture of one or more of alicyclic diol chain extender and diamine chain extender, and the second chain extender is a mixture of one or more of aromatic diol chain extender and diamine chain extender;

Or the first chain extender is a mixture of one or more of aromatic diol chain extender and diamine chain extender, and the second chain extender is a mixture of one or more of alicyclic diol chain extender and diamine chain extender.

Wherein the first chain extender is one or more of cis-cyclohexane-1, 4-diol, 1-methylcyclohexane-1, 4-diol, 4' -diamino dicyclohexylmethane, 1, 2-diamino cyclohexane, isophorone diamine and 1, 4-cyclohexanediamine.

Wherein the second chain extender is one or more of 4,4 '-biphenol, hydroquinone dihydroxyethyl ether, 4' -diaminobenzanilide, 4 '-diaminodibenzyl, 4' -diaminobenzophenone, benzidine, p-phenylenediamine and 1, 4-xylylenediamine.

Wherein the addition of the first chain extender and the second chain extender determines the mechanical properties of the polyurethane polymer, and the mechanical properties of the polyurethane polymer can be adjusted by adjusting the addition of the first chain extender and the second chain extender. Preferably, the total moles of the first and second chain extenders are the same as the moles of polyol in the polyurethane prepolymer.

Wherein the molar ratio of the first chain extender to the second chain extender is 1:1, thus enabling a balance of strength-toughness to be achieved.

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.

Wherein the polyurethane prepolymer is prepared by the following method:

Mixing polyether or polyester polyol with an organic solvent to obtain a mixed solution, specifically, placing the polyester polyol into a reaction vessel, stirring under the oil bath condition of 100-150 ℃ and the inert gas atmosphere, removing water and drying, adding the organic solvent into the reaction vessel as the reaction solvent, and uniformly stirring to obtain the mixed solution, wherein the ratio of the polyester polyol to the organic solvent is 1:20-1:1 g/mL, and the preferable ratio of the polyester polyol to the organic solvent is 1:1-1:3 g/mL;

mixing the mixed solution, diisocyanate, a catalyst and an organic solvent for a prepolymerization reaction to obtain a polyurethane prepolymer, wherein the ratio of the 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, and preferably, the ratio of the diisocyanate to the added organic solvent in the step is 1:5-1:10 g/mL;

the molar ratio of the polyether or polyester polyol to the diisocyanate is 1:2-1:2.4, the temperature of the prepolymerization reaction is 60-100 ℃, and the reaction time is 2-5 h.

Wherein the diisocyanate is one or more of toluene-2, 4-diisocyanate, 4 '-dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate, and the diisocyanate is preferably alicyclic diisocyanate, preferably isophorone diisocyanate or 4,4' -dicyclohexylmethane diisocyanate.

The catalyst is one or more of amine catalyst and organic metal catalyst.

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

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

The polyurethane polymer is applied to intelligent manufacturing, aerospace and flexible electronics.

The beneficial effects of the invention are as follows:

(1) The polyurethane polymer has a flexible alicyclic six-atom and aromatic benzene ring structure, realizes remarkable improvement in tensile strength and toughness, has the tensile strength of 90.4 MPa and the toughness of 275.5 MJ/m ³, and shows excellent mechanical properties.

(2) The polyurethane polymer of the present invention has excellent film forming property and heat resistance.

(3) The invention adopts two-step chain extension reaction, can realize ordered chain segment arrangement to form a block structure, and the block structure is an ordered optimizable material which has a microphase separation structure (hard segment micro-area and soft segment micro-area are distributed), thereby improving mechanical property and stability.

Drawings

Fig. 1 is an infrared spectrogram of examples 1 to 3 and comparative examples 1 and 2 of the present invention.

Fig. 2 is an infrared spectrogram of examples 4 to 6 and comparative examples 3 and 4 of the present invention.

Fig. 3 is an Atomic Force Microscope (AFM) image of comparative example 1.

Fig. 4 is an Atomic Force Microscope (AFM) image of comparative example 2.

Fig. 5 is an Atomic Force Microscope (AFM) image of example 1.

Fig. 6 is an Atomic Force Microscope (AFM) image of example 2.

Fig. 7 is an Atomic Force Microscope (AFM) image of example 3.

Fig. 8 is an Atomic Force Microscope (AFM) image of comparative example 3.

Fig. 9 is an Atomic Force Microscope (AFM) image of comparative example 4.

Fig. 10 is an Atomic Force Microscope (AFM) image of example 4.

Fig. 11 is an Atomic Force Microscope (AFM) image of example 5.

FIG. 12 is an Atomic Force Microscope (AFM) image of example 6.

FIG. 13 is a thermogravimetric analysis graph of example 2.

Fig. 14 is a stress-strain graph of examples 1 to 3 and comparative examples 1 and 2 according to the present invention.

Fig. 15 is a stress-strain graph of examples 4 to 6 and comparative examples 3 and 4 according to the present invention.

FIG. 16 is a hydrogen nuclear magnetic resonance spectrum of example 2 of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.

Unless otherwise indicated, all reagents used in the examples below were commercially available.

1. polyurethane prepolymer preparation (prepolymerization):

Firstly, selecting proper polyether or polyester polyol (the molecular weight range is 1000-3000), mixing, placing into a three-neck flask, introducing nitrogen into the flask under the oil bath condition of 100-150 ℃ for stirring (30-120 min), and fully removing water and other impurities;

After the temperature of the mixed solution is cooled to 60-100 ℃, adding an equivalent amount of diisocyanate (the diisocyanate can be one or more of toluene-2, 4-diisocyanate (2, 4-TDI), 4' -dicyclohexylmethane diisocyanate (HMDI), diphenylmethane diisocyanate (MDI), hexamethylene Diisocyanate (HDI) and isophorone diisocyanate (IPDI), taking a certain amount of organic solvent (the optional solvent is one or more of N, N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), tetrahydrofuran and N-methylpyrrolidone (NMP), mixing and dripping into a reaction bottle, and dripping a small amount of catalyst (the optional catalyst is amine catalyst and organic metal catalyst; amine catalyst is selected from triethylamine, N-dimethylcyclohexylamine, N-dimethylbenzylamine and the like; organic metal catalyst is selected from dibutyltin dilaurate, stannous octoate, isozinc and the like), reacting in N ₂ h of polyurethane to obtain the polyurethane in an N-2-35 h atmosphere.

2. First chain extension reaction:

After the preparation of the prepolymer is completed, a first chain extension reaction is carried out to obtain a chain extension product. The first chain extension reaction adopts a mixture of one or more of aromatic diol chain extender and diamine chain extender, and can also adopt a mixture of one or more of alicyclic diol chain extender and diamine chain extender.

Specifically, adding a first chain extender into a prepolymer, taking a certain amount of the same organic solvent, adding the organic solvent into a reaction bottle, and carrying out the reaction in an N ₂ atmosphere at the reaction temperature of 60-100 ℃ for 1-3 hours to obtain a chain extension product.

3. Second chain extension reaction:

And adding a second chain extender into the chain extension product to perform a second chain extension reaction. The second chain extender is a different type of chain extender than the first chain extender. Specifically, the first chain extender is an aromatic chain extender, the second chain extender is an alicyclic chain extender, and the first chain extender is an alicyclic chain extender, and the second chain extender is an aromatic chain extender.

Specifically, the chain extension product, a second chain extender and an organic solvent are mixed for a second chain extension reaction, and the polyurethane polymer can be obtained, wherein the temperature of the second chain extension reaction is 60-100 ℃ and the time is 1-3 hours.

4. After the reaction is finished, pouring the solution into a polytetrafluoroethylene die, and carrying out vacuum and drying treatment for 24-72 hours at 60-120 ℃ to remove the residual solvent, thereby obtaining the polyurethane elastomer film.

The polyurethane polymer prepared by the invention adopts a flexible alicyclic six-atom structure to replace a rigid aromatic interval, and two chain extenders are added step by step, compared with the process of adding the two chain extenders simultaneously, the polyurethane polymer has the following remarkable advantages:

(1) The ordered chain segments are arranged, namely, step reaction allows one chain extender to be introduced to react with the prepolymer to form a specific chain segment, and then the second chain extender is used for extending to realize a block structure. The ordering can optimize microphase separation (such as distribution of hard segment micro-regions and soft segment micro-regions) of the material, thereby improving mechanical properties (such as tensile strength and toughness) and thermal stability.

(2) The generation of byproducts is reduced, namely, competing reactions can be initiated by adding two chain extenders simultaneously, so that byproducts are generated, and the occurrence of the problems can be effectively reduced by adding the chain extenders step by step.

(3) Avoiding the gelation risk that the simultaneous addition of two chain extenders may lead to local gelation, and the stepwise addition can reduce the risk of process runaway.

Preferably, the first chain extender is a mixture of one or more of a cycloaliphatic diol chain extender and a diamine chain extender, and the second chain extender is a mixture of one or more of an aromatic diol chain extender and a diamine chain extender.

The preparation method adopts one or more of alicyclic diol chain extender and diamine chain extender as chain extender, wherein the optional diol chain extender comprises cis-cyclohexane-1, 4-diol and 1-methylcyclohexane-1, 4-diol, and the diamine chain extender comprises one or more of 4,4' -diamino dicyclohexylmethane, 1, 2-diamino cyclohexane, isophorone diamine and 1, 4-cyclohexanediamine, and the reaction structural formula is shown as follows:

;

Or (b)

。

The aromatic diol chain extender and diamine chain extender may be one or several kinds of mixture, including 4,4 '-biphenol, dihydroxyethyl hydroquinone ether, 4' -diaminobenzanilide, 4 '-diaminodibenzyl, 4' -diaminobenzophenone, benzidine, p-phenylenediamine and 1, 4-xylylenediamine.

Aiming at the inherent contradiction between the strength and the toughness of the traditional polyurethane material, the invention designs a novel polyurethane elastomer based on the synergistic enhancement of a dynamic hydrogen bond network (a three-dimensional network structure formed by intermolecular or intramolecular interconnection of carbamate (-NHCOO-) and ureido (-NH-COO-NH-) groups in a structural formula) and a flexible alicyclic six-atom structure through hydrogen bonds) through a molecular engineering strategy, breaks through the balance limit of mechanical properties, and provides an innovative solution for the development of high-performance structural materials.

The invention realizes remarkable improvement on the tensile strength and toughness, the tensile strength reaches 90.4 MPa, the toughness is 275.5 MJ/m ³, and the invention shows excellent mechanical properties. In order to achieve the aim, a flexible alicyclic six-atom structure is adopted to replace a rigid aromatic space, so that the molecular chains are promoted to be closely stacked, meanwhile, the dynamic movement capacity of chain segments is reserved, and brittle fracture is avoided. Meanwhile, the material effectively dissipates energy under the action of external force by virtue of strong dipole interaction formed by ureido (-NH-COO-NH-) and by virtue of a fracture and recombination mechanism of a dynamic hydrogen bond, so that the strength and toughness are enhanced. In addition, the polarity difference of the hard segment and the soft segment drives the formation of the nanoscale micro-region, so that a microphase separation structure is optimized, and the transmission efficiency of interface stress is further improved.

The invention solves the long-term contradiction between the strength and the toughness of the polyurethane material through the precise regulation and control of the non-covalent interaction of molecular scale, and the polyurethane material prepared by the invention has adjustable mechanical properties, including high strength, high toughness, excellent stretchability, excellent film forming property, heat resistance and the like. The method provides a brand new thought for molecular design of high-performance high-molecular materials, and has remarkable industrial application potential.

Example 1

(1) 10Mmol (20.0 g) of polycarbonate diol (PCDL-2000) with a molecular weight of 2000 g/mol) and 25mL of N, N-Dimethylformamide (DMF) are firstly weighed and mixed into a three-neck flask, and the mixture is stirred for 60min under the oil bath condition of 120 ℃ and the N ₂ atmosphere, so that water and other impurities are sufficiently removed.

(2) Next, after the above-mentioned mixture was cooled to 80 ℃, 20mmol (4.45 g) of IPDI (isophorone diisocyanate, molecular weight 222.29 g/mol) was weighed, 25mL of N, N-Dimethylformamide (DMF) was taken as an organic solvent, and after mixing, it was added to a three-necked flask, and 0.02g of dibutyltin dilaurate (DBTDL) was added as a catalyst, and the prepolymerization was carried out under an oil bath condition at 80℃under an atmosphere of N ₂ with stirring for 3 hours to obtain an isocyanate-terminated polyurethane prepolymer.

(3) After the prepolymerization was completed, 2.5mmol (0.53 g) of 4,4' -diaminodicyclohexylmethane (DDM) was weighed, 62mL of DMF solvent was taken, mixed, sonicated until completely dissolved, and added to a three-necked flask, and the reaction was stirred under an oil bath condition at 80℃and an atmosphere of N ₂, with a reaction time of 60 min.

(4) Next, 7.5mmol (0.92 g) of the chain extender in solid form, namely Benzidine (BZ), was weighed, 38mL of DMF solvent was taken, mixed, sonicated until complete dissolution was achieved, and the mixture was added to a three-necked flask, and the reaction was stirred under an N ₂ atmosphere at 80℃under an oil bath for a reaction time of 60 min.

(5) At the end of the reaction, the solution was poured into a polytetrafluoroethylene mold, treated under vacuum, dried at 80 ℃ for 48 hours, and the residual solvent was removed, and the sample was designated as example 1.

Example 2

The procedure is as in example 1, except that the first chain extender 4,4' -diaminodicyclohexylmethane (DDM) is used in an amount of 5 mmol and the second chain extender Benzidine (BZ) is used in an amount of 5 mmol. Samples were also named example 2.

Example 3

The procedure is as in example 1, except that the first chain extender 4,4' -diaminodicyclohexylmethane (DDM) is used in an amount of 7.5mmol and the second chain extender Benzidine (BZ) is used in an amount of 2.5 mmol. Samples were also named example 3.

Comparative example 1

(3) After the prepolymerization reaction was completed, 10mmol (1.84 g) of a solid chain extender, benzidine (BZ), was weighed, 50mL of DMF solvent was taken, mixed, sonicated until complete dissolution was achieved, and added to a three-necked flask, and the reaction was stirred under an oil bath condition at 80℃and an N ₂ atmosphere for a reaction time of 60 min.

(4) At the end of the reaction, the solution was poured into a polytetrafluoroethylene mold, vacuum-dried at 80 ℃ for 48 hours to remove the residual solvent, and designated as comparative example 1.

Comparative example 2

(1) 10Mmol of polycarbonate diol (PCDL-2000) with a molecular weight of 2000g/mol and 25mL of N, N-Dimethylformamide (DMF) are firstly weighed, mixed and placed in a three-neck flask, and stirred for 60min under the oil bath condition of 120 ℃ and the N ₂ atmosphere, so that water and other impurities are sufficiently removed.

(2) Next, after the above-mentioned mixture was cooled to 80 ℃,20 mmol,4.45g of IPDI (isophorone diisocyanate, molecular weight 222.29 g/mol) was weighed, 25mL of N, N-Dimethylformamide (DMF) was taken as an organic solvent, and after mixing, it was added to a three-necked flask, and 0.02g of dibutyltin dilaurate (DBTDL) was added as a catalyst, and the prepolymerization was carried out under an oil bath condition at 80℃under an atmosphere of N ₂ with stirring for 3 hours to obtain an isocyanate-terminated polyurethane prepolymer.

(3) After the prepolymerization reaction is completed, 10mmol of 2.1g of chain extender 4,4' -diamino dicyclohexylmethane is weighed, 50mL of DMF solvent is measured, the two solvents are mixed, ultrasonic treatment is carried out until the solvent is completely dissolved, the mixture is added into a three-neck flask, and the reaction is stirred under the oil bath condition with the temperature of 80 ℃ and the N ₂ atmosphere, and the reaction time is 60 min.

(4) At the end of the reaction, the solution was poured into a polytetrafluoroethylene mold, vacuum-dried at 80 ℃ for 48 hours to remove the residual solvent, and designated as comparative example 2.

Example 4

(2) Next, after the above-mentioned mixture was cooled to 80 ℃,20 mmol (3.48 g) of 2,4-TDI (toluene-2, 4-diisocyanate, molecular weight 174.16 g/mol) was weighed, 25mL of N, N-Dimethylformamide (DMF) was taken as an organic solvent, and after mixing, it was added to a three-necked flask, and 0.02g of dibutyltin dilaurate (DBTDL) was added as a catalyst, and the prepolymerization was carried out under stirring in an oil bath at 80℃under an N ₂ atmosphere for 3 hours to obtain an isocyanate-terminated polyurethane prepolymer.

(5) At the end of the reaction, the solution was poured into a polytetrafluoroethylene mold, vacuum-dried at 80 ℃ for 48 hours, and the residual solvent was removed and designated as example 4.

Example 5

The procedure is as in example 4, except that the first chain extender 4,4' -diaminodicyclohexylmethane (DDM) is used in an amount of 5 mmol and the second chain extender Benzidine (BZ) is used in an amount of 5 mmol. The sample was named example 5.

Example 6

The procedure is as in example 4, except that the first chain extender 4,4' -diaminodicyclohexylmethane (DDM) is used in an amount of 7.5mmol and the second chain extender Benzidine (BZ) is used in an amount of 2.5 mmol. The sample was named example 6.

Comparative example 3

(4) At the end of the reaction, the solution was poured into a polytetrafluoroethylene mold, vacuum-dried at 80 ℃ for 48 hours to remove the residual solvent, and designated as comparative example 3.

Comparative example 4

(4) At the end of the reaction, the solution was poured into a polytetrafluoroethylene mold, vacuum-dried at 80 ℃ for 48 hours to remove the residual solvent, and designated as comparative example 4.

Example 7

(1) 10Mmol (20.0 g) of polycarbonate diol (PCDL-2000) with a molecular weight of 2000 g/mol) and 30mL of N, N-Dimethylformamide (DMF) are firstly weighed, mixed and placed in a three-neck flask, and stirred for 60min under the oil bath condition of 120 ℃ and the N ₂ atmosphere, so that water and other impurities are sufficiently removed.

(2) Then, after the above-mentioned mixture was cooled to 80 ℃, 24mmol (6.3 g) of 4,4' -dicyclohexylmethane diisocyanate (molecular weight: 262.35 g/mol) was weighed, 60mL of N, N-Dimethylformamide (DMF) was taken as an organic solvent, and after mixing, it was added to a three-necked flask, and 0.03g of dibutyltin dilaurate (DBTDL) was added as a catalyst, and the prepolymerization was stirred under an oil bath condition at 80 ℃ in an atmosphere of N ₂ for 3 hours to obtain an isocyanate-terminated polyurethane prepolymer.

(3) After the prepolymerization reaction was completed, 6mmol (0.78 g) of 1-methylcyclohexane-1, 4-diol was weighed, 62mL of DMF solvent was measured, mixed, sonicated until complete dissolution was achieved, and added to a three-necked flask, and the reaction was stirred under an oil bath condition at 80℃and an atmosphere of N ₂ for a reaction time of 120 min.

(4) Subsequently, 8mmol (1.82 g) of 4,4' -diaminobenzanilide was weighed out, 38mL of DMF solvent was taken, mixed, sonicated until complete dissolution was achieved, and added to a three-necked flask, and the reaction was stirred under an oil bath condition at 80℃and an atmosphere of N ₂ for a reaction time of 60 min.

(5) After the reaction is finished, pouring the solution into a polytetrafluoroethylene mould, carrying out vacuum and drying treatment for 48 hours at 80 ℃, and removing the residual solvent to obtain the polyurethane polymer.

Example 8

(1) 10Mmol (20.0 g) of polycarbonate diol (PCDL-2000) with a molecular weight of 2000 g/mol) and 60mL of N, N-Dimethylformamide (DMF) are firstly weighed, mixed and placed in a three-neck flask, and stirred for 60min under the oil bath condition of 120 ℃ and the N ₂ atmosphere, so that water and other impurities are sufficiently removed.

(2) Then, after the above-mentioned mixture was cooled to 80 ℃, 22mmol (5.77 g) of 4,4' -dicyclohexylmethane diisocyanate was weighed, 50mL of N, N-Dimethylformamide (DMF) was measured as an organic solvent, and after mixing, it was added to a three-necked flask, and 0.03g of dibutyltin dilaurate (DBTDL) was added as a catalyst, and the prepolymerization was carried out under an oil bath condition at 80 ℃ under an atmosphere of N ₂ for 3 hours to obtain an isocyanate-terminated polyurethane prepolymer.

(3) After the prepolymerization reaction was completed, 5mmol (0.54 g) of p-phenylenediamine was weighed, 38mL of DMF solvent was taken, mixed, sonicated until completely dissolved, and added to a three-necked flask, and the reaction was stirred under an oil bath at 80℃and an atmosphere of N ₂ for a reaction time of 60 min.

(4) Next, 4mmol (0.46 g) of 1, 4-cyclohexanediamine was weighed out, 62mL of DMF solvent was taken, mixed, sonicated until completely dissolved, and added to a three-necked flask, and the reaction was stirred under an oil bath at 80℃and an atmosphere of N ₂ for a reaction time of 60: 60 min.

Test results and analysis:

1. Characterization analysis:

Fig. 1 and 2 are fourier infrared (FTIR) spectra of examples 1 to 6 and comparative examples 1 to 4. From the figure, it can be seen that the characteristic peak of the N-H group appears at 3380 cm ^-1, the telescopic vibration peak of 1738cm ^-1 ascribed to the carbonyl group (-C=O-) in the carbamate (-NHCOO-) group, the characteristic peak at 1240cm ^-1 is the stretching vibration peak of the-C-O-part in the carbamate (-NHCOO-) group, and the characteristic peak of the-NCO group does not appear at 2260-2280 cm ^-1, which proves that the polyurethane elastomer is successfully prepared.

In addition, the nmr spectrum of example 2 was also characterized, and fig. 16 shows the nmr spectrum of example 2 in deuterated CDCI ₃, and the positions of the respective characteristic peaks are as follows. 7.27ppm is the off-peak position of the solvent deuterated CDCI ₃, the-CH group of Benzidine (BZ) corresponds to the two off-peak positions, 4.1ppm is the off-peak position of PCDL-2000, 3.79ppm, 2.92ppm and 0.93ppm correspond to the-CH, -CH ₂ and-CH ₃ groups of isophorone diisocyanate (IPDI), respectively, and 1.06ppm to 1.71ppm are the-CH and-CH ₂ groups of isophorone diisocyanate (IPDI) and 4,4' -diaminodicyclohexylmethane (DDM). The position of these peaks reflects the response of the hydrogen atoms of the different parts of the molecule in the magnetic field, which also shows successful preparation from the above analysis.

Microphase structures and surface morphologies of examples 1 to 6 and comparative examples 1 to 4 were systematically characterized using Atomic Force Microscopy (AFM). The microphase structure of the sample was observed by an atomic force microscope in the tapping mode, with a scanning area size of 3 μm×3 μm. See in particular fig. 3 to 7 and fig. 8 to 12.

From the results shown in FIGS. 3 to 7 and 8 to 12, the AFM phase diagrams of the six examples and the four comparative examples each show a distinct bright-dark contrast region, clearly revealing microphase separation characteristics of the soft and hard segments in the polyurethane system, the dark regions corresponding to amorphous phases formed by the polyester diol as soft segments, and the bright regions resulting from aggregation of the hard segment portions built up from the isocyanate and the chain extender. The microphase separation behavior has important significance on the mechanical properties of the material, and moderate microphase separation can obviously improve the strength and toughness of the material through the synergistic effect of a hard segment physical cross-linked network and a soft segment flexible matrix. By further comparison, the bright-dark phase region of example 2 was found to be most clearly defined, with the highest degree of phase separation, while the phase region of comparative example 3 was found to be most blurred, indicating a weaker degree of microphase separation. The result is completely consistent with mechanical test data, and the fact that the proportion and compatibility of soft and hard segments are regulated and controlled through molecular design is fully verified, so that microphase separation behavior of polyurethane can be effectively optimized, and excellent comprehensive mechanical properties are further provided for the material.

By means of accurate molecular design, the polyurethane elastomer with high strength, high toughness and extraordinary stretchability is constructed, and the trade-off limit of the traditional high polymer material between strength and toughness is broken through. We have conducted comparative studies on polymers of similar but slightly different structure by optimizing the structure of the hard segments to achieve the intended goal of polyurethane elastomers. The structure of the optimized hard segment in the embodiment means that the hard segment is formed by isocyanate and a chain extender, and the structure of the hard segment is optimized by changing the type of the isocyanate, namely replacing a rigid aromatic space with a relatively flexible alicyclic six-atom structure, so that the overall strength and toughness of the material are improved.

Compared with the traditional aromatic interval, the polyurethane material prepared by the invention adopts a more flexible alicyclic six-atom interval structure so as to promote close accumulation among molecules and strengthen hydrogen bond density, thereby improving the overall strength and toughness of the material. The unique molecular construction mode not only improves the stability of the polymer chain, but also provides a high-efficiency energy dissipation mechanism when stressed, so that the strength of the polyurethane is 90.4 MPa, and the toughness is 275.5 MJ/m ³.

2. Performance analysis

2.1 Thermal Properties

To effectively evaluate the thermal properties of the prepared optimal material, thermogravimetric analysis was performed on example 2. The test atmosphere was nitrogen and the test temperature was in the range of 50 ℃ to 750 ℃. FIG. 13 is a thermogravimetric analysis (TGA) diagram of example 2. As shown in fig. 13, the thermogravimetric analysis shows that example 2 shows higher thermal stability, the initial thermal decomposition temperature (T _d, the temperature corresponding to 5% weight loss of the sample) is 283.4 ℃, which is superior to most polyurethane elastomers, shows good heat resistance, meets the requirements of various practical applications, and is expected to be applied in extreme conditions or complex environments.

2.2 Mechanical properties

To effectively evaluate the mechanical properties of the prepared polyurethane materials, stress-strain tests were performed on the elastomeric films of the six examples and four comparative examples using a tensile tester. The test standard is GB/T1040-2006, the test speed (stretching rate) is 100 mm/min, and the test environment is 25 ℃. The tensile strength, elongation at break, toughness (curve integration area) and other test results were compared, and the obtained results are shown in fig. 14 and 15, and the related data are summarized in table 1.

Table 1 ultimate tensile strength, elongation at break and toughness for examples 1 to 6 and comparative examples 1 to 4

As is clear from the results of FIGS. 14, 15 and Table 1, comparative example 2 had a tensile strength (i.e., ultimate engineering stress) of 33.5MPa, an elongation at break of 1132%, a toughness of 121.2 MJ/m ³, and comparative example 1 had a tensile strength (i.e., ultimate engineering stress) of 37.7MPa, an elongation at break of 1114%, and a toughness of 144.2 MJ/m ³. In contrast, the tensile strength of example 2 is as high as 90.4 MPa, which is improved by a factor of 2.4 to 2.7 compared to comparative example 2 and comparative example 1. Example 2 still maintained a higher elongation at break of 972% resulting in a toughness of 275.5 MJ/m ³, which was improved by a factor of 1.91 to 2.27 compared to comparative example 2 and comparative example 1. Example 2 shows extremely high tensile strength, outstanding tensile properties and high toughness, which are significantly improved compared to example 5. This shows that the overall strength and toughness of the material can be effectively improved by optimizing the structure of the hard segment using a more flexible alicyclic six-atom structure (IPDI) instead of the rigid aromatic spacer (TDI).

It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.

The foregoing examples, which are not specifically described in part of the present specification as being well known in the art, are provided for the purpose of describing the present invention only and are not intended to limit the scope of the present invention. The scope of the invention is defined by the appended claims. Various equivalents and modifications that do not depart from the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims

1. The polyurethane polymer is characterized by having a structural general formula:

;

Wherein x and y are positive integers, and x >1, y >1, R is R ₁ or R ₂;R₁ or R ₂, the structural formula is as follows:

;

。

2. The polyurethane polymer of claim 1, wherein x and y are equal in value.

3. The polyurethane polymer of claim 1, wherein x is 1 to 13 and y is 1 to 13.

4. A process for producing a polyurethane polymer as claimed in any one of claims 1 to 3, characterized in that the process comprises the steps of:

Mixing polyurethane prepolymer, a first chain extender and an organic solvent for a first chain extension reaction to obtain a chain extension product, wherein the temperature of the first chain extension reaction is 60-100 ℃ and the time is 1-3 h;

Mixing the chain extension product, a second chain extender and an organic solvent for a second chain extension reaction to obtain the polyurethane polymer, wherein the temperature of the second chain extension reaction is 60-100 ℃ and the time is 1-3 h;

5. The method for producing a polyurethane polymer according to claim 4, wherein the alicyclic diol chain extender and diamine chain extender are one or more of cis-cyclohexane-1, 4-diol, 1-methylcyclohexane-1, 4-diol, 4' -diaminodicyclohexylmethane, 1, 2-diaminocyclohexane, isophoronediamine, and 1, 4-cyclohexanediamine;

The aromatic diol chain extender and diamine chain extender are one or more of 4,4 '-biphenol, hydroquinone dihydroxyethyl ether, 4' -diaminobenzanilide, 4 '-diaminodibenzyl, 4' -diaminobenzophenone, benzidine, p-phenylenediamine and 1, 4-xylylenediamine.

6. The method for producing a polyurethane polymer according to claim 4, wherein the total number of moles of the first chain extender and the second chain extender is the same as the number of moles of the polyol in the polyurethane prepolymer.

7. The method of producing a polyurethane polymer according to claim 6, wherein the molar ratio of the first chain extender to the second chain extender is 1:1.

8. The method for producing a polyurethane polymer according to claim 4, wherein 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.

9. The method for producing a polyurethane polymer according to claim 4, wherein the polyurethane prepolymer is produced by:

mixing polyether or polyester polyol with an organic solvent to obtain a mixed solution;

mixing the mixed solution, diisocyanate, a catalyst and an organic solvent for a prepolymerization reaction to obtain polyurethane prepolymer;

10. The method for producing a polyurethane polymer according to claim 9, wherein the diisocyanate is one or more of toluene-2, 4-diisocyanate, 4' -dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate;

The catalyst is an amine catalyst and an organic metal catalyst;

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

11. Use of a polyurethane polymer according to any one of claims 1 to 3 in smart manufacture, aerospace and flexible electronics.