A polyurethane material containing a metal organic framework and a method of making the same

Abstract

The application discloses a polyurethane material containing a metal organic framework and a preparation method thereof. The polyurethane material comprises a polyurethane matrix and a metal organic framework uniformly dispersed in the polyurethane matrix, and the content of the metal organic framework is 2-6 wt%. The metal organic framework is UiO-66. The preparation method comprises the following steps: (1) mixing polyethylene glycol, the metal organic framework and a first solvent, removing the first solvent by using a distillation process, introducing the polyethylene glycol into the pore of the metal organic framework, and obtaining PEG@MOF; (2) mixing the polyethylene glycol, diisocyanate and PEG@MOF, adding a catalyst, and performing a prepolymerization reaction; (3) adding 1,4-butanediol and a catalyst, performing a chain extension reaction, adding a second solvent, and drying to obtain the polyurethane material. In step (1), the mass ratio of the polyethylene glycol to the metal organic framework is 1:1-3. The polyurethane material provided by the application can achieve the effects of excellent dispersibility and excellent mechanical properties.

Description

Technical Field

[0001] This invention relates to polyurethane materials, and more particularly to a polyurethane material containing a metal-organic framework and its preparation method. Background Technology

[0002] Polyurethane is a typical polymer material. Its unique microscopic phase separation structure gives it the advantage of a wide and adjustable range of mechanical properties, and it is currently widely used in many fields such as construction, transportation, medicine, and military. However, due to technological advancements, traditional polyurethane materials, while meeting certain mechanical properties, also need to possess some special functions. The most economical and effective method to achieve this is to fill the polyurethane matrix with functional fillers, especially inorganic functional particles. However, inorganic particle fillers differ significantly from the polyurethane matrix in properties. Their high hydrophilicity makes them prone to agglomeration in the hydrophobic polyurethane polymer matrix, leading to uneven dispersion. These agglomerates easily become stress concentration points, significantly reducing the mechanical properties of the polyurethane material, thus potentially resulting in more harm than good.

[0003] To address this issue, a typical solution involves surface modification of the filler, altering its hydrophilic / hydrophobic properties and polarity to improve its dispersion in the polyurethane matrix. However, the modification effect is limited. Literature reports (Li Bing, Sun Siwei, Wang Miao, et al. Research progress on the properties of MOFs / polyurethane composites [J]. Plastics Technology, 2023, 51(9):123-128) that metal-organic frameworks (MOFs), as emerging inorganic functional fillers, are often used to fill polyurethanes due to their tunable pore structure and abundant unsaturated sites. To improve the poor dispersibility of MOFs, the unsaturated sites are often modified, allowing them to react and bind tightly with the polyurethane chains. From the perspective of polymer chain movement, when polymer chains move, the system entropy increases, but the filler does not move, thus further hindering its effective dispersion. Therefore, existing solutions cannot effectively improve the dispersibility of the material. Summary of the Invention

[0004] Objective of the invention: The objective of this invention is to provide a polyurethane material containing a metal-organic framework with excellent dispersibility and mechanical properties; another objective of this invention is to provide a method for preparing the above-mentioned polyurethane material.

[0005] Technical solution: The polyurethane material containing a metal-organic framework according to the present invention includes a polyurethane matrix and a metal-organic framework uniformly dispersed in the polyurethane matrix, wherein the content of the metal-organic framework is 2-8 wt%.

[0006] Preferably, the metal-organic framework is one of UiO-66, MOF-5, UiO-67, and UiO-68.

[0007] The method for preparing the polyurethane material of the present invention includes the following steps: (1) After mixing polyethylene glycol, metal-organic framework and first solvent, the first solvent is removed by distillation process, and polyethylene glycol is introduced into the pores of metal-organic framework to obtain PEG@MOF; (2) Mix polyethylene glycol, diisocyanate and PEG@MOF and add a catalyst to carry out a prepolymerization reaction; (3) Add 1,4-butanediol and catalyst to carry out chain extension reaction, then add a second solvent and dry to obtain polyurethane material.

[0008] In step (1), the molecular weight of polyethylene glycol is 1500, and the mass ratio of polyethylene glycol to metal-organic framework is 1:1-3; the first solvent is one or more of acetonitrile, dichloromethane, methanol, and ethanol, and the process used to remove the first solvent is a distillation process with a distillation temperature of 80-100℃ and a reaction time of 3-6 hours.

[0009] In step (2), the amount of polyethylene glycol in PEG@MOF is 1-3% of the total mass of polyethylene glycol in the system. The prepolymerization reaction temperature is 70-90℃, and the reaction time is 2-4 hours. The diisocyanate is one or more of toluene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and lysine diisocyanate.

[0010] The catalyst mentioned in steps (2) and (3) is dibutyltin dilaurate; the amount of dibutyltin dilaurate used is 0.1-0.4% of the system mass.

[0011] The second solvent mentioned in step (3) is one or more of toluene, tetrahydrofuran, and ethyl acetate. The chain extension reaction is carried out at a temperature of 70-90℃ for 1-3 hours.

[0012] Invention Principle: This invention addresses the prominent problem of uneven dispersion of inorganic functional particles in polyurethane materials by providing a MOF-containing polyurethane material with excellent dispersibility and its preparation method. A bulk polymerization method is employed, utilizing the porous structure of MOFs. Polyol polymer chains are introduced into the MOF channels through distillation and participate in polyurethane synthesis, maintaining structural stability. This allows the MOF to move with the molecular chains during the reaction, thereby improving the dispersion of MOF within the polyurethane chain and ensuring uniform dispersion of MOF in the polyurethane. The effectiveness of this method is investigated by selecting different isocyanates and adjusting the amount of MOF added, ultimately yielding a MOF-containing polyurethane material with excellent dispersibility.

[0013] In addition, in this method, PEG is introduced into the MOF nanopores. PEG remains disordered in the pores and forms entanglements with itself and MOF. PEG@MOF participates in the reaction, changing the spatial arrangement of PU chains, increasing the degree of entanglement of polyurethane molecular chains, increasing the pathways for energy dissipation during stretching, and thus improving the mechanical properties of polyurethane materials.

[0014] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The method can effectively improve the dispersion of inorganic particle fillers in polyurethane matrix, reduce the agglomeration of inorganic particles, and make the dispersion more uniform; (2) The mechanical properties of the polyurethane material prepared by the method are effectively improved. Compared with the polyurethane material obtained by simply blending MOF with polyurethane matrix, its tensile strength improvement rate is as high as 92.3%-283.1%. Attached Figure Description

[0015] Figure 1 The N2 adsorption curves of UiO-66 and PEG@UiO-66 are shown. Figure 2 SEM images of polyurethane prepared in Examples 1-3 and Comparative Example 1; Figure 3 SEM images of polyurethane obtained in Examples 4-6 and Comparative Example 2; Figure 4 The stress-strain curves of the polyurethanes prepared in Examples 1-3 and Comparative Example 1 are shown. Figure 5 The stress-strain curves of the polyurethanes prepared in Examples 4-6 and Comparative Example 2 are shown. Figure 6 The strain scan curves of the polyurethanes prepared in Examples 1-3 and Comparative Example 1 are shown. Figure 7 The strain scan curves of the polyurethanes prepared in Examples 4-6 and Comparative Example 2 are shown. Detailed Implementation

[0016] The technical solution of the present invention will be further described below with reference to the embodiments.

[0017] Example 1

[0018] The polyurethane material containing a metal-organic framework according to the present invention includes a polyurethane matrix and a metal-organic framework uniformly dispersed in the polyurethane matrix, wherein the content of the metal-organic framework is 2wt%.

[0019] The method for preparing the polyurethane material of the present invention includes the following steps: (1) After mixing 0.5g of polyethylene glycol (PEG-1500), 1g of UiO-66 and 5mL of acetonitrile evenly, the mixture was reacted at 85℃ for 5 hours in a distillation apparatus to remove the acetonitrile solvent and obtain PEG@UiO-66.

[0020] (2) In a detachable four-necked flask equipped with a stirrer and a condenser, add 1.88 g of dehydrated PEG-1500, 3.02 g of isophorone diisocyanate (IPDI), and 0.36 g of PEG@UiO-66. Add 0.2% dibutyltin dilaurate (DBTDL) as a catalyst, evacuate the flask, purge with nitrogen, and carry out a prepolymerization reaction at 80°C for 3 hours. The total mass of the system is the total mass of IPDI, PEG-1500, and BDO.

[0021] (3) Add 0.48 g of dried 1,4-butanediol (BDO), and then add 0.2% DBTDL by weight of the system as a catalyst. Perform a chain extension reaction at 80°C for 2 hours. After the reaction, cool to 40°C, add 10 ml of tetrahydrofuran as a solvent to reduce viscosity, pour into a mold, and let stand at room temperature for 24 hours. Then, dry in a 50°C oven for 48 hours before demolding. The resulting product is a polyurethane material containing MOF with excellent dispersibility. The system weight is the total weight of IPDI, PEG-1500, and BDO.

[0022] In this embodiment, the molar ratio of raw materials IPDI, PEG-1500, and BDO is 5.1:3:2.

[0023] Example 2

[0024] The difference from Example 1 is that in step (2), the amount of PEG-1500 and PEG@UiO-66 added is 11.76g and 0.72g, respectively.

[0025] Example 3

[0026] The difference from Example 1 is that in step (2), the amount of PEG-1500 and PEG@UiO-66 added is 11.64g and 1.08g, respectively.

[0027] Example 4

[0028] The difference from Example 1 is that in step (2), 3.02g of IPDI is replaced with 3.42g of dicyclohexylmethane diisocyanate (HMDI), and the amounts of PEG-1500 and PEG@UiO-66 added are 11.385g and 0.345g, respectively; in step (3), the amount of BDO added is 0.46g. In this example, the molar ratio of raw materials HMDI, PEG-1500, and BDO is 5.1:3:2.

[0029] Example 5

[0030] The difference from Example 4 is that in step (2), the amount of PEG-1500 and PEG@UiO-66 added is 11.27g and 0.69g, respectively.

[0031] Example 6

[0032] The difference from Example 4 is that in step (2), the amount of PEG-1500 and PEG@UiO-66 added is 11.155g and 1.035g, respectively.

[0033] Comparative Example 1 The difference from Example 1 is that step (1) is deleted; in step (2), the amounts of PEG-1500 and UiO-66 added are 12g and 0.72g, respectively. In the preparation process of this comparative example, the polyol was not introduced into the MOF channels by distillation, and the product obtained was a polyurethane material blended with MOF and polyurethane matrix.

[0034] Comparative Example 2 The difference from Example 4 is that step (1) is deleted; in step (2), the amounts of PEG-1500 and UiO-66 added are 11.5g and 0.69g, respectively. In the preparation process of this comparative example, the polyol was not introduced into the MOF channels by distillation, and the product obtained was a polyurethane material blended with MOF and polyurethane matrix.

[0035] Table 1. Test results of mechanical properties of each sample sample Tensile strength / MPa Elongation at break / % 100% constant tensile stress / MPa 300% constant tensile stress / MPa Example 1 1.25 672.43 1.24 0.81 Example 2 1.98 639.7 1.98 1.32 Example 3 2.49 555.06 2.48 1.74 Comparative Example 1 0.65 626.88 0.63 0.44 Example 4 3.7 510.83 1.38 2.41 Example 5 4.54 561.69 3.11 3.95 Example 6 3.15 558.65 1.72 2.49 Comparative Example 2 2.47 385.99 1.85 2.43 Table 2 Strain scanning results for each sample sample 1% constant strain stress / KPa 10% constant strain stress / KPa 100% constant strain stress / kPa Example 1 125.36 90.8 57.68 Example 2 128.04 74.91 48.36 Example 3 133.72 75.24 39.62 Comparative Example 1 160.5 91.9 27.42 Example 4 335.92 187.08 109.94 Example 5 348.95 166.19 89.87 Example 6 364.16 133.83 88.3 Comparative Example 2 314.17 113.09 28.38 N2 adsorption tests were performed on the UiO-66 and PEG@UiO-66 described in this invention, and the results are as follows: Figure 1As shown in the curve, it can be clearly seen that the N2 adsorption capacity of PEG@UiO-66 is much smaller than that of UiO-66, that is, the pores of UiO-66 are significantly reduced, indicating that PEG has successfully entered the pores of UiO-66, that is, step (1) of the present invention has successfully prepared PEG@UiO-66.

[0036] from Figure 2 and Figure 3 As can be observed, in the polyurethane materials prepared using the method described in this invention (Examples 1-6), the MOF is uniformly dispersed in the polyurethane matrix without obvious agglomeration, and even with an increase in MOF content, its agglomeration degree remains low. However, in the polyurethane materials prepared using the conventional MOF-polyurethane matrix blending process (Comparative Examples 1 and 2), the MOF exhibits obvious agglomeration and is extremely unevenly dispersed.

[0037] from Figure 4 As can be seen from the curves and the data of Examples 1-3 and Comparative Example 1 in Table 1, compared with Comparative Example 1, Example 3, which added the same mass of UiO-66, has a higher tensile strength. The maximum tensile strength increased from 0.65 MPa to 2.49 MPa, an increase of 283.1%. Compared with Examples 1-3, the tensile strength of polyurethane increased accordingly with the increase of PEG@UiO-66 addition, with maximum tensile strengths of 1.25 MPa, 1.98 MPa, and 2.49 MPa, respectively. Figure 5 The curves and data in Table 1 for Examples 4-6 and Comparative Example 2 show the same results for Examples 6 and Comparative Example 2, which added the same mass of UiO-66. Compared with Examples 4-6, the tensile strength of the polyurethane remained or increased with the increase of PEG@UiO-66 addition. The polyurethane obtained by the preparation method provided by the present invention has better mechanical properties.

[0038] The strength of the Payne effect indirectly reflects the dispersion of fillers in polyurethane materials. The more pronounced the Payne effect, the larger ΔG', and the worse the filler dispersion. Figure 6 The curves and the data from Examples 1-3 and Comparative Example 1 in Table 2 clearly show that, under the same strain, ΔG' of Examples 1-3 is smaller than ΔG' of Comparative Example 1, indicating a weaker Payne effect. Figure 5 The data in Table 2 show that the inorganic filler UiO-66 exhibits better dispersibility in Examples 1-3. Correspondingly, Figure 7 The data from Examples 4-6 and Comparative Example 2 in Table 2 also reflect the same results. It is evident that the polyurethane prepared by the method provided by this invention exhibits better filler dispersion than polyurethane obtained by directly filling fillers.

Claims

1. A polyurethane material containing a metal-organic framework, characterized in that, It includes a polyurethane matrix and a metal-organic framework uniformly dispersed in the polyurethane matrix, with the metal-organic framework content being 2-8 wt%.

2. The polyurethane material according to claim 1, characterized in that, The metal-organic framework is one of UiO-66, MOF-5, UiO-67, and UiO-68.

3. The method for preparing the polyurethane material according to claim 1 or 2, characterized in that, Includes the following steps: (1) After mixing polyethylene glycol, metal-organic framework and first solvent, the first solvent is removed to obtain PEG@MOF; (2) Mix polyethylene glycol, diisocyanate and PEG@MOF and add a catalyst to carry out a prepolymerization reaction; (3) Add 1,4-butanediol and catalyst to carry out chain extension reaction, then add a second solvent and dry to obtain polyurethane material.

4. The preparation method according to claim 3, characterized in that, In step (1), the molecular weight of polyethylene glycol is 1500, and the mass ratio of polyethylene glycol to metal-organic framework is 1:1-3; the first solvent is one or more of acetonitrile, dichloromethane, methanol, and ethanol, and the process used to remove the first solvent is distillation, with a distillation temperature of 80-100℃ and a reaction time of 3-6 hours.

5. The preparation method according to claim 3, characterized in that, In step (2), the amount of polyethylene glycol in PEG@MOF is 1-3% of the total mass of polyethylene glycol in the system.

6. The preparation method according to claim 3, characterized in that, The temperature of the prepolymerization reaction in step (2) is 70-90℃ and the reaction time is 2-4 hours.

7. The preparation method according to claim 3, characterized in that, The diisocyanate mentioned in step (2) is one or more of toluene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and lysine diisocyanate.

8. The preparation method according to claim 3, characterized in that, The catalyst mentioned in steps (2) and (3) is dibutyltin dilaurate; the amount of dibutyltin dilaurate used is 0.1-0.4% of the system mass.

9. The preparation method according to claim 3, characterized in that, The second solvent mentioned in step (3) is one or more of toluene, tetrahydrofuran, and ethyl acetate.

10. The preparation method according to claim 3, characterized in that, In step (3), the chain extension reaction is carried out at a temperature of 70-90°C for 1-3 hours.

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