Highly water-absorbing non-isocyanate polyurethane elastomers and their preparation and use
By reacting epoxy compounds with hyperbranched polyamines to construct highly absorbent NIPU elastomers, the problems of swelling and strength reduction caused by hydrophilicity in NIPU elastomers during alcohol-water separation are solved, achieving efficient and low-cost alcohol-water separation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUHAN INST OF TECH
- Filing Date
- 2026-02-26
- Publication Date
- 2026-05-29
AI Technical Summary
Existing NIPU elastomers suffer from excessive hydrophilicity during alcohol-water separation, leading to swelling and decreased mechanical strength. This makes it difficult to achieve both high water absorption and high mechanical strength simultaneously under mild conditions, limiting their application in the food and pharmaceutical fields.
Hydroxyl-containing NIPU elastomers are formed by reacting epoxy compounds with hyperbranched polyamines under mild conditions. A continuous hydrophilic microphase is constructed through a hydrogen bond network, and hyperbranched polyamines are introduced to enhance the crosslinking network, thereby improving mechanical properties and anti-swelling ability.
A highly absorbent NIPU elastomer was prepared under normal pressure and low temperature, achieving excellent alcohol-water separation with a low-carbon alcohol purity of up to 99.5%, and maintaining structural integrity even when absorbing 4.5 times its weight in water.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of absorbent materials technology, specifically to a NIPU elastomer for efficient water / alcohol separation, its preparation method, and its application. Background Technology
[0002] Polyurethane elastomers, as a type of polymer material with tunable properties, possess excellent comprehensive performance and can be widely used in the field of adsorption separation. However, traditional polyurethanes rely on toxic isocyanate monomers, which not only pose environmental and health risks but also limit their application in high-standard fields such as food and pharmaceuticals.
[0003] Non-isocyanate polyurethanes (NIPUs) based on the ring-opening polymerization of cyclic carbonates and amine compounds avoid the use of isocyanates and have become a research frontier in the field of green polymer materials due to their excellent biocompatibility and environmental friendliness. More importantly, the abundant polar groups such as hydroxyl groups in NIPU molecules give them excellent hydrophilicity, which provides unique potential for alcohol-water separation applications that require preferential adsorption and transport of water molecules.
[0004] However, the application of NIPU elastomers in efficient alcohol-water separation processes still faces two core challenges. First, to achieve high water / alcohol selectivity, NIPU elastomers must possess strong hydrophilicity to preferentially adsorb and transport water molecules; however, excessive hydrophilicity can lead to excessive swelling in alcohol-water solutions, not only reducing its sieving capacity and selectivity but also causing a significant loss of mechanical strength or even elastomer rupture, thus affecting the separation effect. At the same time, existing NIPU synthesis processes struggle to simultaneously achieve high mechanical strength, precisely controllable hydrophilicity, and a stable anti-swelling network structure under mild, low-cost, and environmentally friendly conditions, which greatly limits its practical application potential.
[0005] Therefore, how to obtain NIPU elastomers with high water absorption and high mechanical strength through a simple reaction under mild conditions and at low cost is a problem that needs to be solved. Summary of the Invention
[0006] In view of this, the present invention provides a NIPU elastomer for efficient separation of water / alcohol and a method for preparing the same.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] A method for preparing a highly absorbent NIPU elastomer includes the following steps:
[0009] 1) Add the epoxy compound to the reactor, purge with carbon dioxide until the pressure reaches 0.5~3.0 MPa, and react at 25-80 ℃ for 24-48 h to obtain cyclic carbonate;
[0010] 2) Add cyclic carbonate and hyperbranched polyamine to the reactor at a molar ratio of 1-1.3:0.5 and react at 25-100℃ for 2-24 h;
[0011] 3) After the reaction is complete, cool to room temperature, add water and acid, stir to swell and age to obtain NIPU elastomer.
[0012] Preferably, the epoxy compound is one or more of terminal epoxy polyethylene glycol, butadiene dioxide, dicyclohexyl glycol, and diepoxyglycerol ether.
[0013] Preferably, the hyperbranched polyamine includes one or more of polyamide-amine, polyethyleneimine, and polypropyleneimine.
[0014] Preferably, in step 3), the mass ratio of water to cyclic carbonate is 1-5:1, the pH value of the acid is 1-3, the swelling temperature is 25-50 °C, and the swelling time is 2-12 h.
[0015] Preferably, the acid includes one or more of benzoic acid, acetic acid, oxalic acid, citric acid, tartaric acid, malonic acid, glycolic acid, and phthalic acid.
[0016] Preferably, the aging time is 1-48 h and the temperature is 20-50℃.
[0017] The present invention also relates to a highly absorbent NIPU elastomer obtained by the above preparation method and its application in the field of water / alcohol separation.
[0018] Preferably, the alcohol is a C2-C4 low-carbon alcohol.
[0019] Preferably, the highly absorbent NIPU elastomer is used for water / low alcohol separation, with the elastomer dosage being 1%-10% of the mass of the liquid to be separated, and the separation time being 2-4 hours.
[0020] This invention uses raw materials containing hydrophilic groups and utilizes the hydroxyl structure of NIPU to form a hydrogen bond network, constructing a continuous hydrophilic microphase; it introduces hyperbranched polyamines as rigid segments to strengthen the formation of the NIPU crosslinking network, giving it excellent water molecule transport capabilities while improving the material's mechanical properties and anti-swelling ability.
[0021] The NIPU elastomer preparation method provided by this invention uses clean and safe raw materials and mild reaction conditions. While contributing to national carbon emission reduction, it also exhibits excellent separation effect in alcohol-water separation systems, providing a brand-new solution for achieving green and low-cost bio-alcohol dehydration processes.
[0022] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:
[0023] (1) The preparation method of the present invention has mild reaction conditions, and can efficiently react to obtain NIPU elastomer materials at normal pressure and low temperature. Moreover, the reaction materials used in the production process are simple, clean, safe and low cost, and suitable for large-scale production applications.
[0024] (2) The highly absorbent NIPU elastomer provided by the present invention has high mechanical strength and water absorption efficiency. When applied to the water / alcohol high efficiency separation process, the purity of the low carbon alcohol obtained is >99.5%, and the structure remains intact when the water absorption is 4.5 times its own weight, maintaining high alcohol / water selectivity. Detailed Implementation
[0025] This invention provides a method for preparing a NIPU elastomer with efficient water / alcohol separation, comprising the following steps:
[0026] 1) Add the epoxy compound to the reactor, purge with carbon dioxide until the pressure reaches 0.5~3.0 MPa, and react at 25-80 ℃ for 24-48 h to obtain cyclic carbonate.
[0027] 2) Add cyclic carbonate and hyperbranched polyamine to the reactor at a molar ratio of 1-1.3:0.5 and react at 25-100℃ for 2-24 h.
[0028] 3) After the reaction is complete, cool to room temperature, add water and acid, stir to swell and age to obtain NIPU elastomer.
[0029] In this invention, the epoxy compound is one or more of terminal epoxy polyethylene glycol, butadiene dioxide, dicyclohexyl glycol, and diepoxyglycerol ether.
[0030] In this invention, the hyperbranched polyamine includes one or more of polyamide-amine, polyethyleneimine, and polypropyleneimine.
[0031] In this invention, the reaction temperature in step 2) is 25-100℃, specifically 25℃, 35℃, 50℃, 60℃, 75℃, 80℃, or 95℃; the reaction time is 2-24 h, specifically 4 h, 8 h, 12 h, 18 h, or 24 h.
[0032] In this invention, the mass ratio of water to cyclic carbonate added in step 3) is 1-5:1, preferably 2-5:1, more preferably 3-4:1, and even more preferably 3:1; the pH value of the acid is 1-3, specifically 1, 2, or 3. In this invention, the swelling in step 3) is preferably a stirring swelling, with a stirring rate of 100-400 rpm, specifically 100 rpm, 150 rpm, 160 rpm, 180 rpm, 200 rpm, 250 rpm, 350 rpm, or 380 rpm, and a stirring swelling time of 2-12 h, specifically 2 h, 6 h, 8 h, 10 h, or 12 h.
[0033] In this invention, the acid includes one or more of benzoic acid, acetic acid, oxalic acid, citric acid, tartaric acid, malonic acid, glycolic acid, and phthalic acid.
[0034] In this invention, the aging time in step 3) is 1-48 h, specifically 2 h, 8 h, 12 h, 24 h, 32 h, 40 h, or 48 h, and the aging temperature is 20-50℃.
[0035] Preferably, the prepared elastomer is used for water / low alcohol separation, with the amount of elastomer being 1%-10% of the mass of the liquid to be separated, and the separation time being 2-4 h.
[0036] The present invention also provides a NIPU elastomer prepared by the aforementioned preparation method.
[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0038] Example 1
[0039] (1) Butadiene dioxide was added to the reactor, carbon dioxide was introduced until the pressure reached 3.0 MPa, and the reaction was carried out at room temperature for 24 h to obtain cyclic carbonate.
[0040] (2) Add the obtained cyclic carbonate (3.1g) and polyethyleneimine (2.1g) to a 50 mL beaker, place the beaker in a constant temperature reactor, maintain the temperature at 80℃, react at this temperature for 5 h, then remove the beaker, cool to room temperature, and obtain the product.
[0041] (3) Add water (12.4 g) to the cooled beaker, then add oxalic acid solution (0.4 mL) with pH 3, stir and swell at 25 °C and 400 rpm for 2 h, and then age at 20 °C for 1 h to obtain NIPU elastomer, labeled as sample A.
[0042] Example 2
[0043] (1) Add dicyclohexyldiol to the reactor, introduce carbon dioxide until the pressure reaches 0.8 MPa, and react at room temperature for 48 h to obtain cyclic carbonate.
[0044] (2) Add the obtained cyclic carbonate (2.9g) and polyethyleneimine (1.8g) to a 25mL beaker, place the beaker in a constant temperature reactor, maintain the temperature at 25℃, react at this temperature for 12 h, then remove the beaker and cool to room temperature to obtain the product.
[0045] (3) Add water (14.5 g) to the cooled beaker, followed by acetic acid solution (0.3 mL) with pH 2. Stir and swell at 25°C and 250 rpm for 4 h, and then age at 25°C for 48 h to obtain NIPU elastomer, which is labeled as sample B.
[0046] Example 3
[0047] (1) Add dicyclohexyldiol to the reactor, introduce carbon dioxide until the pressure reaches 1.5 MPa, and react at room temperature for 36 h to obtain cyclic carbonate.
[0048] (2) Add the obtained cyclic carbonate (3.5g), polypropylene imine (1.1g), and polypropylene imine (0.9g) to a 50 mL beaker. Place the beaker in a constant temperature reactor and maintain the temperature at 100℃. React at this temperature for 2 h. Then remove the beaker and cool it to room temperature to obtain the product.
[0049] (3) Add water (3.5g) to the cooled beaker, then add tartaric acid solution (0.2mL) with pH 1, stir and swell at 25℃ and 100 rpm for 6 h, and then age at 30℃ for 24 h to obtain NIPU elastomer, labeled as sample C.
[0050] Example 4
[0051] (1) Add diepoxyglycerol ether to the reactor, introduce carbon dioxide until the pressure reaches 2.5 MPa, and react at room temperature for 40 h to obtain cyclic carbonate.
[0052] (2) Add the obtained cyclic carbonate (3.5 g) and polyethyleneimine (2.0 g) to a 50 mL beaker, place the beaker in a constant temperature reactor, maintain the temperature at 100 °C, react at this temperature for 2 h, then remove the beaker and cool to room temperature to obtain the product.
[0053] (3) Add water (3.5 g) to the cooled beaker, then add acetic acid solution (0.2 mL) with pH 2, stir and swell at 25°C and 100 rpm for 6 h, and then age at 25°C for 24 h to obtain NIPU elastomer, labeled as sample D.
[0054] Example 5
[0055] (1) Add diepoxyglycerol ether to the reactor, introduce carbon dioxide until the pressure reaches 3.0 MPa, and react at room temperature for 24 h to obtain cyclic carbonate.
[0056] (2) Add the obtained cyclic carbonate (3.5g), polypropyleneimine (1.1g), and polypropyleneimine (1.2g) to a 50mL beaker, place the beaker in a constant temperature reactor, maintain the temperature at 100℃, react at this temperature for 2 h, then remove the beaker and cool to room temperature to obtain the product.
[0057] (3) Add water (3.5g) to the cooled beaker, then add acetic acid solution (0.3mL) with pH 3, stir and swell at 25℃ and 100 rpm for 6 h, and then age at 25℃ for 48 h to obtain NIPU elastomer, labeled as sample E.
[0058] Comparative Example 1
[0059] (1) Add diepoxyglycerol ether to the reactor, introduce carbon dioxide until the pressure reaches 3.0 MPa, and react at room temperature for 24 h to obtain cyclic carbonate.
[0060] (2) Add the obtained cyclic carbonate (3.5g) and ethylenediamine (2.1g) to a 50mL beaker, place the beaker in a constant temperature reactor, maintain the temperature at 100℃, react at this temperature for 2 h, then remove the beaker, cool to room temperature, and obtain the product.
[0061] (3) Add water (3.5g) to the cooled beaker, then add oxalic acid solution (0.3mL) with pH 3, stir and swell at 25℃ and 100rpm for 6 h, and then age at 25℃ for 48 h to obtain NIPU elastomer, labeled as sample F.
[0062] Comparative Example 2
[0063] (1) Add 3.5g of trimethylene carbonate and 1.2g of polyimide to a 50 mL beaker, place the beaker in a constant temperature reactor, maintain the temperature at 100℃, react at this temperature for 2 h, then remove the beaker and cool to room temperature to obtain the product.
[0064] (2) Add water (3.5 g) to the cooled beaker, followed by acetic acid solution (0.3 mL) with pH 3. Stir and swell at 25°C and 100 rpm for 6 h, and then age at 25°C for 48 h to obtain NIPU elastomer, labeled as sample G.
[0065] Application Example 1
[0066] The water (5%) / ethanol mixture was placed in a 50mL beaker at a mass ratio of 1:100. The sample A prepared in Example 1 was added to the beaker and allowed to stand for 2 hours. The elastomer was then removed and its mass after absorption was recorded. An appropriate amount of the separated mixture was taken and the purity of ethanol was calculated to be 99.5%.
[0067] Application Example 2
[0068] The water (3%) / ethanol mixture was placed in a 50 mL beaker at a mass ratio of 5:100 (elastomer to water-ethanol mixture). Sample B prepared in Example 2 was added to the beaker and allowed to stand for 4 h. The elastomer was then removed, and its mass after absorption was recorded. An appropriate amount of the separated mixture was taken, and the purity of the ethanol after separation was calculated to be 99.8%.
[0069] Application Example 3
[0070] The water (10%) / ethanol mixture was placed in a 50 mL beaker at a mass ratio of 8:100 (elastomer to water-ethanol mixture). The sample C prepared in Example 3 was added to the beaker and allowed to stand for 3 h. The elastomer was then removed, and its mass after absorption was recorded. An appropriate amount of the separated mixture was taken, and the purity of the ethanol after separation was calculated to be 99.8%.
[0071] Application Example 4
[0072] Take a water (4%) / propanol mixture at a mass ratio of 1:100 to elastomer and place it in a 50 mL beaker. Add the sample D prepared in Example 4 into the beaker and let it stand for 3 h. Then take out the elastomer, record its mass after absorption, and take an appropriate amount of the separated mixture to calculate the purity of the ethanol after separation as 99.7%.
[0073] Application Example 5
[0074] The water (8%) / tert-butanol mixture was placed in a 50 mL beaker at a mass ratio of 1:100. The sample E prepared in Example 5 was added to the beaker and allowed to stand for 1 h. The elastomer was then removed, and its mass after absorption was recorded. An appropriate amount of the separated mixture was taken, and the purity of the ethanol after separation was calculated to be 99.8%.
[0075] Comparative Example 3
[0076] The water (5%) / ethanol mixture was prepared at a mass ratio of 1:100 to the elastomer and placed in a 50 mL beaker. The sample F prepared in Comparative Example 1 was added into the beaker and allowed to stand for 2 hours. The elastomer was then removed and found to be broken. No further tests were performed.
[0077] Comparative Example 4
[0078] A water (5%) / ethanol mixture was prepared at a mass ratio of 1:100 to elastomer and water-ethanol mixture and placed in a 50 mL beaker. Sample G prepared in Comparative Example 2 was then added to the beaker. The elastomer was found to float on the water. After standing for 4 hours, the elastomer was removed and an appropriate amount of the separated mixture was taken. The purity of ethanol was calculated to be 95.3%, indicating that the separation effect was not good.
[0079] The performance of the NIPU elastomers prepared in Examples 1-5 and Comparative Examples 1-2 (corresponding to samples A, B, C, D, E, F, and G in sequence) was tested. The standards used for the tests and the test results are shown in Table 1.
[0080] Table 1. Structure and Separation Properties of NIPU Elastomer
[0081]
[0082] Note: Sample F*'s elastomer fractured, therefore no relevant product performance tests were performed.
[0083] As shown in Table 1, the NIPU elastomers prepared in Examples 1-5 have strong water absorption capacity due to the use of hydrophilic raw materials. Furthermore, the hyperbranched polyamine increases the molecular crosslinking density, resulting in high tensile strength, resistance to breakage, and excellent water / alcohol separation performance. The elastomer prepared in Comparative Example 1, which does not use hyperbranched polyamine, has poor mechanical strength. The elastomer prepared in Comparative Example 2, which does not use a highly hydrophilic ester, has poor water absorption and poor water / alcohol separation performance.
Claims
1. A method for preparing a highly absorbent NIPU elastomer, comprising the following steps: 1) Add the epoxy compound to the reactor, purge with carbon dioxide until the pressure reaches 0.5-3.0 MPa, and react at 25-80℃ for 24-48 h to obtain cyclic carbonate; 2) The cyclic carbonate obtained in step 1) and the hyperbranched polyamine are added to the reactor at a molar ratio of 1-1.3:0.5 and reacted at 25-100℃ for 2-24 h. 3) After the reaction is complete, cool to room temperature, add water and acid, stir to swell and age to obtain NIPU elastomer.
2. The method for preparing a highly absorbent NIPU elastomer according to claim 1, characterized in that, The epoxy compound is one or more of terminal epoxy polyethylene glycol, butadiene dioxide, dicyclohexyl glycol, and diepoxyglycerol ether.
3. The method for preparing a highly absorbent NIPU elastomer according to claim 1, characterized in that, The hyperbranched polyamine includes one or more of polyamide-amine, polyethyleneimine, and polypropyleneimine.
4. A method for preparing a highly absorbent NIPU elastomer according to any one of claims 1-3, characterized in that, In step 3), the mass ratio of water to cyclic carbonate added is 1-5:1, the pH value of the acid is 1-3, the swelling temperature is 25-50℃, and the swelling time is 2-12 h.
5. A method for preparing a highly absorbent NIPU elastomer according to claim 4, characterized in that, The acid includes one or more of benzoic acid, acetic acid, oxalic acid, citric acid, tartaric acid, malonic acid, glycolic acid, and phthalic acid.
6. A method for preparing a highly absorbent NIPU elastomer according to claim 1, characterized in that, The aging time is 1-48 hours, and the temperature is 20-50℃.
7. A highly absorbent NIPU elastomer prepared by the preparation method according to any one of claims 1-6.
8. The application of the highly absorbent NIPU elastomer of claim 7 in the field of water / alcohol separation.
9. The application as described in claim 8, characterized in that, The alcohol is a C2-C4 low-carbon alcohol.
10. The application as described in claim 8, characterized in that, The amount of the highly absorbent NIPU elastomer used is 1%-10% of the mass of the liquid to be separated, and the separation time is 2-4 hours.