A bio-based hydrophilic polyurethane water-swellable elastomer and a method of making the same

Abstract

The application belongs to the field of polyurethane materials, and particularly relates to a preparation method of a bio-based hydrophilic polyurethane water-swelling elastomer, which comprises the following steps: step one, uniformly mixing isocyanate, bio-based polycaprolactone polyol, polylactic acid polyol, a catalyst, polyethylene glycol and water, and reacting at room temperature to obtain a reaction liquid; and step two, foaming and curing the reaction liquid to obtain the bio-based hydrophilic polyurethane water-swelling elastomer. The hydrophilic polyurethane swelling elastomer prepared by the application has good hydrophilicity and stable water-swelling performance, and also has good mechanical properties, and has a good application prospect. The bio-based hydrophilic polyurethane water-swelling elastomer prepared by the application has a low preparation cost, is suitable for large-scale batch production, and is conducive to the application of the bio-based hydrophilic polyurethane water-swelling elastomer.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane materials, specifically relating to a bio-based hydrophilic polyurethane water-swellable elastomer and its preparation method. Background Technology

[0002] Hydrophilic materials can be divided into two main categories: those that absorb water and swell, and those that absorb water and do not swell. Materials that absorb water and do not swell do not expand in volume after absorbing water and are mainly used in furniture and clothing. Materials that absorb water and swell, on the other hand, expand in volume several times to tens of times their original size after absorbing water, and have a wider range of applications, showing promising prospects in waterproofing, water conservancy projects, and aquaculture.

[0003] Existing methods for preparing water-absorbing and swelling materials include physical mixing, graft polymerization, and chemical synthesis. Graft polymerization involves grafting specific monomers onto the polymer backbone to form side chains with specific functions, thus endowing the material with water-swellable properties. This method can produce structurally stable and controllable water-swellable materials, but controlling the grafting reaction is complex, requiring precise control of reaction conditions and monomer ratios, which presents a certain challenge. Physical mixing typically involves mixing various raw materials such as rubber, activators, antioxidants, reinforcing agents, and fillers in a certain proportion, and preparing water-absorbing and swelling materials through mechanical mixing or hot pressing. This method is simple to operate and suitable for large-scale production. However, physical mixing may lead to inhomogeneities in material properties, particularly in terms of swelling performance and mechanical strength. Chemical synthesis involves the synthesis of various chemical substances, such as the reaction of polyether-type polyurethane prepolymer and the end-capping agent HEMA. By adding a catalyst and heating, double-bond-terminated polyurethane water-swellable materials are prepared. This method can precisely control the molecular structure of polyurethane water-swellable materials, thereby obtaining materials with specific swelling properties and showing good results.

[0004] Currently, hydrophilic polyurethane water-swellable materials are prepared using polyols and isocyanates containing hydrophilic ethylene ether segments (-CH2-CH2-O-) as raw materials. The proportion of ethylene ether segments in the polyether chain is often controlled within a certain range to impart hydrophilicity and ion resistance. For example, one paper prepared hydrophilic polyurethane foam with a water absorption time of less than 30 seconds using different amounts of ethylene oxide in mixed polyether polyols. However, the hydrophilicity and water-swellable properties of the polyurethane elastomer prepared by this method were not excellent, limiting its application range. Summary of the Invention

[0005] To address the issues of insufficient hydrophilicity and expansion performance of existing polyurethane water-swellable elastomers, this invention provides a bio-based hydrophilic polyurethane water-swellable elastomer and its preparation method.

[0006] The preparation method of this bio-based hydrophilic polyurethane water-swellable elastomer includes the following steps:

[0007] Step 1: Mix isocyanate, bio-based polycaprolactone polyol, polylactic acid polyol, catalyst, polyethylene glycol and water evenly, and react at room temperature to obtain a reaction solution;

[0008] Step 2: The reaction solution is foamed and cured to obtain the bio-based hydrophilic polyurethane water-swellable elastomer.

[0009] In step one, the structural formula of the bio-based polycaprolactone polyol is as follows:

[0010]

[0011] Where R is O and One of them; m is 3-15, n is 3-15;

[0012] The polylactic acid polyol has the following structural formula:

[0013]

[0014] Where a is 3-20 and b is 3-20.

[0015] Further, the isocyanate mentioned in step one is selected from one or more of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate.

[0016] Furthermore, the mass ratio of the bio-based polycaprolactone polyol, polylactic acid polyol, and polyethylene glycol in step one is 100:(50-70):(50-80).

[0017] Furthermore, the ratio of the total mass of the bio-based polycaprolactone polyol, polylactic acid polyol, and polyethylene glycol in step one to the mass of isocyanate is 100:(35-45).

[0018] Furthermore, the mass ratio of the catalyst, water and polylactic acid polyol mentioned in step one is 1:(20-50):(200-300).

[0019] Furthermore, the catalyst mentioned in step one is one of organotin catalysts and amine catalysts.

[0020] Furthermore, the polyethylene glycol mentioned in step one is selected from one or more of polyethylene glycol 500, polyethylene glycol 1000, and polyethylene glycol 2000.

[0021] Furthermore, the polylactic acid polyol is prepared by the following method:

[0022] Step (1): Mix zinc salt, organic ammonium salt and bis(ethylene carbonate) ether and heat to react to obtain an in-situ catalyst;

[0023] Step (2): The purified LA monomer is added to the in-situ catalyst to react and obtain the product.

[0024] The present invention also provides a bio-based hydrophilic polyurethane water-swellable elastomer.

[0025] The bio-based hydrophilic polyurethane water-swellable elastomer is prepared by the preparation method of bio-based hydrophilic polyurethane water-swellable elastomer as described in any of the above claims.

[0026] The beneficial effects of this invention are as follows:

[0027] (1) The method of the present invention uses bio-based polycaprolactone polyol and polylactic acid polyol with hydrophilic flexible segments in combination with polyethylene glycol in a certain proportion, so that the prepared polyurethane water-swellable elastomer has excellent hydrophilicity and water absorption and swelling properties, and has good application prospects.

[0028] (2) In the process of preparing bio-based hydrophilic polyurethane water-swellable elastomer, the present invention adds polyethylene glycol and introduces polyethylene glycol segments into the polyurethane water-swellable elastomer, providing a suitable crosslinking length. Due to the introduction of different segments, the cohesive energy is improved and the intermolecular forces are enhanced, so that the prepared polyurethane water-swellable elastomer has good mechanical properties.

[0029] (3) The bio-based polycaprolactone polyol and polylactic acid polyol prepared by the method of the present invention have low cost, and the cost of using them to prepare polyurethane water-swellable elastomers is also low. Furthermore, the preparation method provided by the present invention is simple and easy to operate, with low equipment requirements, which is conducive to further reducing the preparation cost. It is suitable for large-scale mass production and is beneficial to the application of the prepared bio-based hydrophilic polyurethane water-swellable elastomers. Attached Figure Description

[0030] Figure 1 A flowchart illustrating the preparation method of the bio-based hydrophilic polyurethane water-swellable elastomer provided by this invention. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but this should not be construed as limiting the scope of the present invention.

[0032] The polyethylene glycol 1000, polyethylene glycol 2000, and polyethylene glycol 500 used in the embodiments and comparative examples of this invention were manufactured by Shanghai Maclean Biochemical Technology Co., Ltd.; the δ-CL monomers used were all biologically derived δ-caprolactone.

[0033] The structural formula of the bio-based polycaprolactone polyol of this invention is as follows:

[0034]

[0035] Where R is O and One of them; m is 3-15, n is 3-15.

[0036] Optionally, the preparation methods of bio-based polycaprolactone polyol A, bio-based polycaprolactone polyol B, and bio-based polycaprolactone polyol C used in the embodiments and comparative examples of the present invention are as follows:

[0037] Step 1: Mix zinc salt, organic ammonium salt and initiator, and heat to 180℃ for 4 hours to obtain an in-situ catalyst;

[0038] Step 2: First, add calcium oxide to remove water from the δ-CL monomer, and then purify the δ-CL monomer to obtain purified δ-CL monomer.

[0039] Step 3: Add the purified δ-CL monomer to the in-situ catalyst and react at 170℃ for 1.5 h to obtain the product;

[0040] Step 4: Add methanol to precipitate and separate to obtain bio-based polycaprolactone polyol.

[0041] The selection of zinc salts, organic ammonium salts, and initiators added during the preparation of bio-based polycaprolactone polyol A, bio-based polycaprolactone polyol B, and bio-based polycaprolactone polyol C is shown in Table 1, and the addition ratio of each raw material is shown in Table 2.

[0042] Table 1

[0043]

[0044] Table 2

[0045]

[0046] See Figure 1 A method for preparing a bio-based hydrophilic polyurethane water-swellable elastomer, characterized by comprising the following steps:

[0047] Step 1: Mix isocyanate, bio-based polycaprolactone polyol, polylactic acid polyol, catalyst, polyethylene glycol and water evenly, and react at room temperature to obtain a reaction solution;

[0048] Step 2: The reaction solution is foamed and cured to obtain the bio-based hydrophilic polyurethane water-swellable elastomer.

[0049] In step one, the structural formula of the bio-based polycaprolactone polyol is as follows:

[0050]

[0051] Where R is O and One of them; m is 3-15, n is 3-15;

[0052] The polylactic acid polyol has the following structural formula:

[0053]

[0054] Where a is 3-20 and b is 3-20.

[0055] The method of this invention uses bio-based polycaprolactone polyol, polylactic acid polyol and polyethylene glycol with hydrophilic flexible segments in a certain proportion during the preparation of polyurethane water-swellable elastomer, so that the prepared polyurethane water-swellable elastomer has excellent hydrophilicity and water absorption and swelling properties, as well as good mechanical properties.

[0056] Example 1

[0057] I. Preparation of Polylactic Acid Polyols

[0058] Step (1): Zinc chloride, dimethylaminopyridine and bis(ethylene carbonate) ether were added in a mass ratio of 1:30:40 and mixed together. The mixture was then heated to 200°C and reacted for 2 hours to obtain an in-situ catalyst.

[0059] Step (2): Take the purified LA monomer at a mass ratio of 1:45 of bis(ethylene carbonate) ether to LA monomer, add it to the above in-situ catalyst, and react at 160℃ for 1.5h to obtain the product;

[0060] Step (3): Add methanol to precipitate and separate to obtain polylactic acid polyol.

[0061] II. Preparation of Bio-based Hydrophilic Polyurethane Water-swellable Elastomers

[0062] Step 1: Mix toluene diisocyanate, the above-mentioned bio-based polycaprolactone polyol A, the above-mentioned polylactic acid polyol, dibutyltin dilaurate, polyethylene glycol 1000 and water evenly, and react at room temperature to obtain a reaction solution. The mass ratio of the added bio-based polycaprolactone polyol A, polylactic acid polyol and polyethylene glycol 1000 is 20:12:13. The mass ratio of the total mass of the added bio-based polycaprolactone polyol A, polylactic acid polyol and polyethylene glycol 1000 to the mass of isocyanate is 5:2. The mass ratio of the added dibutyltin dilaurate, water and polylactic acid polyol is 1:35:250.

[0063] Step 2: The reaction solution is foamed at room temperature and 50 bar for 3 minutes, and then cured for 24 hours to obtain the bio-based hydrophilic polyurethane water-swellable elastomer.

[0064] Example 2

[0065] I. Preparation of Polylactic Acid Polyols

[0066] Step (1): Zinc bromide, tetrabutylammonium chloride and bis(ethylene carbonate) ether were added in a mass ratio of 1:10:30. The mixture was heated to 180°C and reacted for 3 hours to obtain an in-situ catalyst.

[0067] Step (2): Take the purified LA monomer at a mass ratio of 1:30 of bis(ethylene carbonate) ether to LA monomer, add it to the above in-situ catalyst and react at 130°C for 2 hours to obtain the product;

[0068] Step (3): Add ethanol to precipitate and separate to obtain polylactic acid polyol.

[0069] II. Preparation of Polyurethane Elastomers

[0070] Step 1: Mix isophorone diisocyanate, the above-mentioned bio-based polycaprolactone polyol B, the above-mentioned polylactic acid polyol, stannous octoate, polyethylene glycol 2000 and water evenly, and react at room temperature to obtain a reaction solution. The mass ratio of the added bio-based polycaprolactone polyol B, polylactic acid polyol and polyethylene glycol 2000 is 2:1:1. The mass ratio of the total mass of the added bio-based polycaprolactone polyol B, polylactic acid polyol and polyethylene glycol 2000 to the mass of isocyanate is 20:7. The mass ratio of the added stannous octoate, water and polylactic acid polyol is 1:20:200.

[0071] Step 2: The reaction solution is foamed at room temperature and 10 bar for 5 minutes, and then cured for 24 hours to obtain the bio-based hydrophilic polyurethane water-swellable elastomer.

[0072] Example 3

[0073] I. Preparation of Polylactic Acid Polyols

[0074] Step (1): Zinc acetate, tetrabutylammonium bromide and bis(ethylene carbonate) ether were added in a mass ratio of 1:50:50. The mixture was heated to 220°C and reacted for 1 hour to obtain an in-situ catalyst.

[0075] Step (2): Take the purified LA monomer at a mass ratio of 1:60 of bis(ethylene carbonate) ether to LA monomer, add it to the above in-situ catalyst and react at 180°C for 1 h to obtain the product;

[0076] Step (3): Add methanol to precipitate and separate to obtain polylactic acid polyol.

[0077] II. Preparation of Bio-based Hydrophilic Polyurethane Water-swellable Elastomers

[0078] Step 1: Take diphenylmethane diisocyanate, the above-mentioned bio-based polycaprolactone polyol C, the above-mentioned polylactic acid polyol, N,N-dimethylcyclohexylamine, polyethylene glycol 500 and water, mix them evenly, and react at room temperature to obtain a reaction solution. The mass ratio of the added bio-based polycaprolactone polyol C, polylactic acid polyol and polyethylene glycol 500 is 10:7:8, the mass ratio of the total mass of the added bio-based polycaprolactone polyol C, polylactic acid polyol and polyethylene glycol 500 to the mass of isocyanate is 20:9, and the mass ratio of the added N,N-dimethylcyclohexylamine, water and polylactic acid polyol is 1:50:300.

[0079] Step 2: The reaction solution is foamed at room temperature and 100 bar for 5 minutes, and then cured for 24 hours to obtain the bio-based hydrophilic polyurethane water-swellable elastomer.

[0080] Example 4

[0081] I. Preparation of Polylactic Acid Polyols

[0082] Step (1): Zinc chloride, tetrabutylammonium iodide and bis(ethylene carbonate) ether were added in a mass ratio of 1:10:50. The mixture was heated to 200℃ and reacted for 2 hours to obtain an in-situ catalyst.

[0083] Step (2): Take the purified LA monomer at a mass ratio of 1:45 of bis(ethylene carbonate) ether to LA monomer, add it to the above in-situ catalyst and react at 150°C for 2 hours to obtain the product;

[0084] Step (3): Add ethanol to precipitate and separate to obtain polylactic acid polyol.

[0085] II. Preparation of Bio-based Hydrophilic Polyurethane Water-swellable Elastomers

[0086] Step 1: Mix hexamethylene diisocyanate, bio-based polycaprolactone polyol B, the above-mentioned polylactic acid polyol, bis(2-dimethylaminoethyl) ether, polyethylene glycol 1000 and water evenly, and react at room temperature to obtain a reaction solution. The mass ratio of bio-based polycaprolactone polyol B, polylactic acid polyol and polyethylene glycol 1000 added is 5:3:4. The mass ratio of the total mass of bio-based polycaprolactone polyol B, polylactic acid polyol and polyethylene glycol 1000 added to the mass of isocyanate is 5:2. The mass ratio of bis(2-dimethylaminoethyl) ether and water added to polylactic acid polyol is 1:50:200.

[0087] Step 2: The reaction solution is foamed at room temperature and 50 bar for 3 minutes, and then cured for 24 hours to obtain the bio-based hydrophilic polyurethane water-swellable elastomer.

[0088] Comparative Example 1

[0089] I. Preparation of Polylactic Acid Polyols

[0090] The preparation of polylactic acid polyol was the same as in Example 1.

[0091] II. Preparation of Bio-based Hydrophilic Polyurethane Water-swellable Elastomers

[0092] In this comparative example, the polycaprolactone polyol used in step one is grade 2302, manufactured by Hunan Juren New Material Co., Ltd.; other technical features are the same as in Example 1.

[0093] Comparative Example 2

[0094] Preparation of bio-based hydrophilic polyurethane water-swellable elastomer

[0095] In this comparative example, the polylactic acid polyol used in step one is PLA220B, manufactured by Shenzhen Guanghua Weiye Co., Ltd.; other technical features are the same as in Example 1.

[0096] Comparative Example 3

[0097] I. Preparation of Polylactic Acid Polyols

[0098] The preparation of polylactic acid polyol was the same as in Example 1.

[0099] II. Preparation of Bio-based Hydrophilic Polyurethane Water-swellable Elastomers

[0100] In step one of this comparative example, the mass ratio of bio-based polycaprolactone polyol, polylactic acid polyol, and polyethylene glycol 1000 is 1:1:1; other technical features are the same as in Example 1.

[0101] Comparative Example 4

[0102] I. Preparation of Polylactic Acid Polyols

[0103] The preparation of polylactic acid polyol was the same as in Example 1.

[0104] II. Preparation of Bio-based Hydrophilic Polyurethane Water-swellable Elastomers

[0105] In step one of this comparative example, the mass ratio of bio-based polycaprolactone polyol, polylactic acid polyol, and polyethylene glycol 1000 is 10:4:5; other technical features are the same as in Example 1.

[0106] Comparative Example 5

[0107] I. Preparation of Polylactic Acid Polyols

[0108] The preparation of polylactic acid polyol was the same as in Example 1.

[0109] II. Preparation of Bio-based Hydrophilic Polyurethane Water-swellable Elastomers

[0110] Step 1: Mix toluene diisocyanate, the above-mentioned polylactic acid polyol, dibutyltin dilaurate, polyethylene glycol 1000 and water evenly, and react at room temperature to obtain a reaction solution. The mass ratio of polylactic acid polyol to polyethylene glycol 1000 added is 12:33, the mass ratio of the total mass of polylactic acid polyol and polyethylene glycol 1000 added to the mass of isocyanate is 5:2, and the mass ratio of dibutyltin dilaurate, water and polylactic acid polyol added is 1:35:250.

[0111] Step 2: The reaction solution is foamed at room temperature and 50 bar for 5 minutes, and then cured for 24 hours to obtain the bio-based hydrophilic polyurethane water-swellable elastomer.

[0112] Comparative Example 6

[0113] Preparation of bio-based hydrophilic polyurethane water-swellable elastomer

[0114] Step 1: Mix toluene diisocyanate, the above-mentioned bio-based polycaprolactone polyol A, dibutyltin dilaurate, polyethylene glycol 1000 and water evenly, and react at room temperature to obtain a reaction solution. The mass ratio of the added bio-based polycaprolactone polyol to polyethylene glycol 1000 is 20:33, the mass ratio of the total mass of the added bio-based polycaprolactone polyol A and polyethylene glycol 1000 to the mass of isocyanate is 5:2, and the mass ratio of the added dibutyltin dilaurate, water and bio-based polycaprolactone polyol is 1:35:250.

[0115] Step 2: The reaction solution is foamed at room temperature and 50 bar for 5 minutes, and then cured for 24 hours to obtain the bio-based hydrophilic polyurethane water-swellable elastomer.

[0116] The hydrophilicity and water absorption swelling properties of the polyurethane elastomers prepared in the examples and comparative examples were tested, and the test results are shown in Table 1.

[0117] The water absorption rate and water absorption swelling rate were tested in accordance with the GB / T 1034-2008 standard.

[0118] Tensile strength and elongation at break were tested in accordance with GB / T6344-2008 standard.

[0119] Table 1

[0120] Water absorption rate (%) Water absorption swelling rate (%) Tensile strength (kPa) Elongation at break (%) Example 1 857 233 85 150 Example 2 959 245 80 140 Example 3 879 249 89 156 Example 4 948 257 92 163 Comparative Example 1 912 206 87 143 Comparative Example 2 903 228 95 159 Comparative Example 3 953 209 92 163 Comparative Example 4 951 202 76 133 Comparative Example 5 818 184 86 139 Comparative Example 6 809 195 64 123

[0121] The test results above show that the bio-based hydrophilic polyurethane water-swellable elastomer prepared by the method of this invention has good hydrophilicity and water absorption and swelling properties. However, in Comparative Examples 1 and 2, the bio-based hydrophilic polyurethane water-swellable elastomers prepared using existing polycaprolactone polyols or polylactic acid polyols have relatively poor water absorption and swelling properties due to the limited number of ethylene ether segments and the limited variety of segments or groups. In Comparative Example 3, a smaller amount of bio-based polycaprolactone polyol was used to prepare the bio-based hydrophilic polyurethane water-swellable elastomer, while a large amount of polyethylene glycol was added. Due to the reduced number of ethylene ether segments and the poor flexibility of the segments, the water absorption and swelling properties of the prepared polyurethane elastomer were relatively poor. In Comparative Example 4, a smaller amount of polylactic acid polyol was used... Bio-based hydrophilic polyurethane water-swellable elastomers prepared from polylactic acid polyols exhibit relatively poor tensile properties and elongation at break due to the limited number of rigid groups. In Comparative Example 5, bio-based hydrophilic polyurethane water-swellable elastomers were prepared without the use of bio-based polycaprolactone polyols, resulting in fewer flexible ethylene ether segments and relatively poor hydrophilic and water-absorbing swelling properties. In Comparative Example 6, bio-based hydrophilic polyurethane water-swellable elastomers were prepared without the use of polylactic acid polyols, resulting in relatively poor water-absorbing swelling properties, tensile strength, and elongation at break due to the limited number of rigid groups and flexible ethylene ether segments.

[0122] Furthermore, the bio-based hydrophilic polyurethane water-swellable elastomer prepared by the method of this invention has a lower cost. The cost of polyurethane elastomers prepared by existing reported technologies using petroleum-based polycaprolactone polyols is 26-35 yuan / kg, while the cost of commercially available bio-based hydrophilic polyurethane water-swellable elastomers is 30-35 yuan / kg. The cost of hydrophilic bio-based polyurethane prepared using the method of this invention is 20-30 yuan / kg, which can significantly reduce the preparation cost of bio-based hydrophilic polyurethane water-swellable elastomers.

Claims

1. A method of preparing a bio-based hydrophilic polyurethane water-swellable elastomer, characterized in that, The method comprises the following steps: Step one, taking isocyanate, bio-based polycaprolactone polyol, polylactic acid polyol, catalyst, polyethylene glycol and water, mixing uniformly, reacting at room temperature to obtain a reaction liquid; Step two, foaming and curing the reaction liquid to obtain the bio-based hydrophilic polyurethane water-swelling elastomer, In step one, the bio-based polycaprolactone polyol has the following structural formula: wherein R is one of O; m is 3-15, n is 3-15; The polylactic acid polyol has the following structural formula: Wherein, a is 3-20, b is 3-20; In step one, the mass ratio of the bio-based polycaprolactone polyol, polylactic acid polyol and polyethylene glycol is 100:(50-70):(50-80); In step one, the ratio of the total mass of the bio-based polycaprolactone polyol, polylactic acid polyol and polyethylene glycol to the mass of isocyanate is 100:(35-45); In step one, the mass ratio of the catalyst, water and polylactic acid polyol is 1:(20-50):(200-300).

2. The method of making a bio-based hydrophilic polyurethane hydroswellable elastomer according to claim 1, wherein, In step one, the isocyanate is selected from one or more of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate and hexamethylene diisocyanate.

3. The method of making a bio-based hydrophilic polyurethane water-swellable elastomer according to claim 1, wherein, In step one, the catalyst is one of organic tin catalyst and amine catalyst.

4. The method of making a bio-based hydrophilic polyurethane water-swellable elastomer of claim 1, wherein, In step one, the polyethylene glycol is selected from one or more of polyethylene glycol 500, polyethylene glycol 1000 and polyethylene glycol 2000.

5. The method of making a bio-based hydrophilic polyurethane water-swellable elastomer according to claim 1, wherein, The polylactic acid polyol is prepared by the following method: Step (1), taking zinc salt, organic ammonium salt and bis(ethylene carbonate) ether, mixing and then heating to react to obtain an in-situ catalyst; Step (2), adding purified LA monomer to the in-situ catalyst to react to obtain a product.

6. A bio-based hydrophilic polyurethane water-swellable elastomer characterized in that, Prepared by the method of any one of claims 1-5. The bio-based hydrophilic polyurethane water-swelling elastomer is prepared by the method of any one of claims 1-5.

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