A high-strength anti-swelling polyurea supramolecular hydrogel and its preparation method

Abstract

The present invention belongs to the field of hydrogel technology, and in particular to a kind of high-strength anti-swelling polyurea supramolecular hydrogel and preparation method thereof. The present invention first uses hydrophilic polyetheramine ED 900 as soft segment, oxalyl dihydrazide (ODH) as chain extender, and solution polymerization occurs together with isophorone diisocyanate (IPDI) to prepare linear polyurea;Then the obtained polyurea solution is formed into a polyurea film by a casting film forming method;Then the polyurea film is placed in water and soaked to swelling equilibrium, i.e., polyurea supramolecular hydrogel is obtained. By introducing stable six-fold hydrogen bonds in hard segment microregions using oxalyl dihydrazide as chain extender, stable physical crosslinking makes polyurea supramolecular hydrogel show excellent mechanical properties and anti-swelling performance;And the preparation method of hydrogel has mild conditions, simple and easy operation, and is easy to implement.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogels, and particularly relates to a high-strength anti-swelling polyurea supramolecular hydrogel and a preparation method thereof. Background Art

[0002] Hydrogel is a kind of soft material composed of a hydrophilic three-dimensional polymer cross-linked network and a large amount of water, and has broad application prospects in many fields. Since many synthetic hydrogels do not reach swelling equilibrium, when they come into contact with water during use, the hydrogel will absorb water and swell. During the swelling process, although the three-dimensional network structure of the hydrogel will not be completely destroyed, the increase in water content and the expansion of the hydrogel volume cause its mechanical properties to seriously decline, greatly limiting the practical application of the hydrogel. To solve the above problems, a feasible method is to give the hydrogel anti-swelling properties to ensure the stability of the mechanical properties of the hydrogel material. For example, patent CN111647110 reports a high-strength anti-swelling chitosan-based physical hydrogel, which overcomes the shortcomings of traditional hydrogels that are easy to absorb water and swell and lose mechanical properties.

[0003] Supramolecular hydrogels are physically crosslinked hydrogels formed through various non-covalent crosslinking interactions. Compared to traditional chemically crosslinked hydrogels, supramolecular hydrogels typically exhibit excellent dynamic mechanical properties due to the reversibility of non-covalent bonds, thus attracting considerable attention. Hydrogen bonds, a type of non-covalent bond, are widely used in the construction of supramolecular hydrogel systems. However, ordinary hydrogen bonds have poor stability in water, making the preparation of hydrogen-bonded crosslinked supramolecular hydrogels with high strength and swelling resistance challenging. By adopting strategies such as forming multiple hydrogen bonds and synergizing with hydrophobic interactions, the stability of hydrogen bonds in water can be increased, resulting in hydrogen-bonded crosslinked supramolecular hydrogels with high strength and swelling resistance. For example, patent CN104804115 reports a supramolecular hydrogel prepared using acryloylglycinamide as a monomer. This supramolecular hydrogel, crosslinked through multiple hydrogen bonds formed between bisamide pendant groups, exhibits excellent mechanical properties and swelling stability. Patent CN103539919 enhances the strength of polyurethane-urea supramolecular hydrogels by utilizing multiple hydrogen bonds within urea bonds and the synergistic effect of hydrophobic aggregation.

[0004] Linear polyureas are multi-block polymers formed by the stepwise polymerization of diisocyanate and amino compounds. Their molecular chains contain numerous urea bonds, which can form double hydrogen bonds. Furthermore, by manipulating the structure of the diisocyanate or chain extender, stable quadruple or sextuple hydrogen bonds can be formed within the hard segment microdomains of the polyurea elastomer. However, the preparation of polyurea supramolecular hydrogels with both excellent mechanical properties and anti-swelling properties remains a question. Summary of the Invention

[0005] In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a high-strength anti-swelling polyurea supramolecular hydrogel and a preparation method thereof.

[0006] A method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel comprises the following steps:

[0007] Adding a solvent to the polyetheramine, and then adding 77% to 100% of the total isocyanate diisocyanate to carry out a prepolymerization reaction; then adding a chain extender and the remaining diisocyanate to carry out chain extension; cooling to room temperature to obtain a polyurea solution;

[0008] forming a polyurea solution into a film to obtain a polyurea film, then immersing the polyurea film in water or simulated seawater for 20-28 hours, and taking it out to obtain a polyurea supramolecular hydrogel;

[0009] The polyetheramine is hydrophilic polyetheramine ED-900, and the chain extender is oxalyl dihydrazide.

[0010] Preferably, the total amount of the diisocyanate is 2-2.6 times the molar amount of the polyetheramine.

[0011] Preferably, the diisocyanate is isophorone diisocyanate.

[0012] Preferably, the prepolymerization reaction conditions are: reaction at 30° C. for 1 hour under nitrogen atmosphere.

[0013] Preferably, the solvent is N,N-dimethylformamide.

[0014] Preferably, the amount of oxalyl dihydrazide added is 1-1.6 times the molar amount of the polyetheramine.

[0015] Preferably, the chain extension reaction conditions are: reaction at 50° C. for 6 hours under nitrogen atmosphere.

[0016] Preferably, the specific steps of forming the polyurea solution into a film are: pouring the polyurea solution into a mold and drying it to obtain a polyurea film.

[0017] The polyurea supramolecular hydrogel prepared according to the aforementioned method has a formation mechanism in which the polyurea film undergoes microphase separation due to the structural differences and thermodynamic incompatibility between the soft segments and hard segments in the polyurea; when the polyurea film is immersed in water, the hydrophilic soft segments swell, and the hard segment microdomains aggregated by multiple hydrogen bonds act as stable physical crosslinking points, forming the polyurea supramolecular hydrogel.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) In the method for preparing polyurea supramolecular hydrogel provided by the present invention, stable six-fold hydrogen bonds are introduced into the hard segment microregion by selecting oxalyl dihydrazide as a chain extender, and the polyurea supramolecular hydrogel is endowed with excellent mechanical properties and anti-swelling properties through stable physical crosslinking.

[0020] (2) The method for preparing polyurea supramolecular hydrogel provided by the present invention has the characteristics of mild reaction conditions, simple operation and easy implementation.

[0021] (3) The polyurea supramolecular hydrogel provided by the present invention exhibits excellent anti-swelling properties and good mechanical property stability when immersed in water or simulated seawater for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the preparation reaction of polyurea in the present invention;

[0023] Figure 2 Schematic diagram of the formation of sixfold hydrogen bonds between diurea structural units connected by oxalyl dihydrazide chain extender;

[0024] Figure 3 This is a diagram showing the water content of polyurea hydrogel after being immersed in water for different times;

[0025] Figure 4 This is a diagram of the water content of polyurea hydrogel after being immersed in simulated seawater for different times. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to specific embodiments.

[0027] Source of raw materials

[0028] Polyetheramine ED-900 was purchased from Yangzhou Chenhua Technology Group Co., Ltd.;

[0029] Isophorone diisocyanate, brand WANNATEIPDI, was purchased from Wanhua Chemical;

[0030] Example 1

[0031] A method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel comprises the following steps:

[0032] (1) Preparation of polyurea solution:

[0033] First, 10 mmol of polyetheramine ED-900, 20 mL of N,N-dimethylformamide (DMF), and 20 mmol of isophorone diisocyanate (IPDI) were sequentially added into a reactor equipped with a stirring device, and prepolymerization reaction was carried out at 30°C under nitrogen protection for 1 hour. Then, 50 mL of DMF was added to reduce the viscosity of the system, and then 10 mmol of oxalyl dihydrazide (ODH) was added, and the chain extension reaction was carried out at 50°C under nitrogen protection for 6 hours. Finally, the product was cooled to room temperature to obtain a polyurea solution.

[0034] (2) Preparation of polyurea film:

[0035] The polyurea solution was poured into a polytetrafluoroethylene mold, dried in a blast drying oven at 70°C for 48 hours and then dried in a vacuum drying oven at 90°C for 24 hours to obtain a polyurea film.

[0036] (3) Preparation of polyurea supramolecular hydrogel:

[0037] The polyurea film is cut into polyurea film strips with a length of 6 cm and a width of 1 cm. The size of the polyurea film can be cut according to the required size. The strips are immersed in water or simulated seawater at room temperature for 24 hours, and then taken out to obtain the polyurea supramolecular hydrogel.

[0038] Example 2

[0039] A method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel comprises the following steps:

[0040] (1) Preparation of polyurea solution:

[0041] First, 10 mmol of polyetheramine ED-900, 20 mL of N,N-dimethylformamide (DMF), and 20 mmol of isophorone diisocyanate (IPDI) were sequentially added into a reactor equipped with a stirring device, and prepolymerization was carried out at 30°C under nitrogen protection for 1 hour. Then, 50 mL of DMF was added to reduce the viscosity of the system, and then 12 mmol of oxalyl dihydrazide (ODH) and 2 mmol of IPDI were added, and the chain extension reaction was carried out at 50°C under nitrogen protection for 6 hours. Finally, the product was cooled to room temperature to obtain a polyurea solution.

[0042] (2) Preparation of polyurea film:

[0043] The polyurea solution was poured into a polytetrafluoroethylene mold, dried in a blast drying oven at 70°C for 48 hours and then dried in a vacuum drying oven at 90°C for 24 hours to obtain a polyurea film.

[0044] (3) Preparation of polyurea supramolecular hydrogel:

[0045] The polyurea film is cut into polyurea film strips with a length of 6 cm and a width of 1 cm. The size of the polyurea film can be cut according to the required size. The strips are immersed in water or simulated seawater at room temperature for 24 hours, and then taken out to obtain the polyurea supramolecular hydrogel.

[0046] Example 3

[0047] A method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel comprises the following steps:

[0048] (1) Preparation of polyurea solution:

[0049] First, 10 mmol of polyetheramine ED-900, 20 mL of N,N-dimethylformamide (DMF), and 20 mmol of isophorone diisocyanate (IPDI) were sequentially added into a reactor equipped with a stirring device, and prepolymerization was carried out at 30°C under nitrogen protection for 1 hour. Then, 50 mL of DMF was added to reduce the viscosity of the system, and then 14 mmol of oxalyl dihydrazide (ODH) and 4 mmol of IPDI were added, and the chain extension reaction was carried out at 50°C under nitrogen protection for 6 hours. Finally, the product was cooled to room temperature to obtain a polyurea solution.

[0050] (2) Preparation of polyurea film:

[0051] The polyurea solution was poured into a polytetrafluoroethylene mold, dried in a blast drying oven at 70°C for 48 hours and then dried in a vacuum drying oven at 90°C for 24 hours to obtain a polyurea film.

[0052] (3) Preparation of polyurea supramolecular hydrogel:

[0053] The polyurea film is cut into polyurea film strips with a length of 6 cm and a width of 1 cm. The size of the polyurea film can be cut according to the required size. The strips are immersed in water or simulated seawater at room temperature for 24 hours, and then taken out to obtain the polyurea supramolecular hydrogel.

[0054] Example 4

[0055] A method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel comprises the following steps:

[0056] (1) Preparation of polyurea solution:

[0057] First, 10 mmol of polyetheramine ED-900, 20 mL of N,N-dimethylformamide (DMF), and 20 mmol of isophorone diisocyanate (IPDI) were sequentially added into a reactor equipped with a stirring device, and prepolymerization was carried out at 30°C under nitrogen protection for 1 hour. Then, 50 mL of DMF was added to reduce the viscosity of the system, and then 16 mmol of oxalyl dihydrazide (ODH) and 6 mmol of IPDI were added, and the chain extension reaction was carried out at 50°C under nitrogen protection for 6 hours. Finally, the product was cooled to room temperature to obtain a polyurea solution.

[0058] (2) Preparation of polyurea film:

[0059] The polyurea solution was poured into a polytetrafluoroethylene mold, dried in a blast drying oven at 70°C for 48 hours and then dried in a vacuum drying oven at 90°C for 24 hours to obtain a polyurea film.

[0060] (3) Preparation of polyurea supramolecular hydrogel:

[0061] The polyurea film is cut into polyurea film strips with a length of 6 cm and a width of 1 cm. The size of the polyurea film can be cut according to the required size. The strips are immersed in water or simulated seawater at room temperature for 24 hours, and then taken out to obtain the polyurea supramolecular hydrogel.

[0062] Example 5

[0063] A method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel comprises the following steps:

[0064] (1) Preparation of polyurea solution:

[0065] First, 10 mmol of polyetheramine ED-900, 20 mL of N,N-dimethylformamide (DMF), and 20 mmol of isophorone diisocyanate (IPDI) were sequentially added into a reactor equipped with a stirring device, and prepolymerization was carried out at 28°C under nitrogen protection for 1.5 hours. Then, 50 mL of DMF was added to reduce the viscosity of the system, and then 14 mmol of oxalyl dihydrazide (ODH) and 4 mmol of IPDI were added, and the chain extension reaction was carried out at 52°C under nitrogen protection for 5.5 hours. Finally, the product was cooled to room temperature to obtain a polyurea solution.

[0066] (2) Preparation of polyurea film:

[0067] The polyurea solution was poured into a polytetrafluoroethylene mold, dried in a blast drying oven at 70°C for 48 hours and then dried in a vacuum drying oven at 90°C for 24 hours to obtain a polyurea film.

[0068] (3) Preparation of polyurea supramolecular hydrogel:

[0069] The polyurea film is cut into polyurea film strips with a length of 6 cm and a width of 1 cm. The size of the polyurea film can be cut according to the required size. The strips are immersed in water or simulated seawater at room temperature for 24 hours, and then taken out to obtain the polyurea supramolecular hydrogel.

[0070] Example 6

[0071] A method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel comprises the following steps:

[0072] (1) Preparation of polyurea solution:

[0073] First, 10 mmol of polyetheramine ED-900, 20 mL of N,N-dimethylformamide (DMF), and 20 mmol of isophorone diisocyanate (IPDI) were sequentially added into a reactor equipped with a stirring device, and prepolymerization was carried out at 35°C under nitrogen protection for 1.2 hours. Then, 50 mL of DMF was added to reduce the viscosity of the system, and then 14 mmol of oxalyl dihydrazide (ODH) and 4 mmol of IPDI were added, and the chain extension reaction was carried out at 55°C under nitrogen protection for 5 hours. Finally, the product was cooled to room temperature to obtain a polyurea solution.

[0074] (2) Preparation of polyurea film:

[0075] The polyurea solution was poured into a polytetrafluoroethylene mold, dried in a blast drying oven at 70°C for 48 hours and then dried in a vacuum drying oven at 90°C for 24 hours to obtain a polyurea film.

[0076] (3) Preparation of polyurea supramolecular hydrogel:

[0077] The polyurea film is cut into polyurea film strips with a length of 6 cm and a width of 1 cm. The size of the polyurea film can be cut according to the required size. The strips are immersed in water or simulated seawater at room temperature for 24 hours, and then taken out to obtain the polyurea supramolecular hydrogel.

[0078] The thickness of the polyurea film obtained in the examples of this application is about 0.65 mm, and the thickness of the polyurea supramolecular hydrogel is about 0.9 mm. The samples in Examples 1-4 were tested using the following test methods:

[0079] (1) Determination of molecular weight and distribution of polyurea

[0080] The polyurea solution was dripped into deionized water to precipitate. The precipitate was collected and washed three times with diethyl ether, then dried under vacuum at 30°C. The molecular weight and distribution of the polyurea were determined using gel permeation chromatography (GPC) with a mobile phase of DMF + 10 mM LiBr at a temperature of 35°C and a flow rate of 1 mL / min. The standard sample was polystyrene. The results are shown in Table 1 below.

[0081] (2) Determination of water content of polyurea supramolecular hydrogel

[0082] Cut a piece of polyurea film and weigh it (W0), soak it in water / simulated seawater at room temperature for 24 hours, take it out and wipe the surface moisture of the sample and weigh it (W t ), the calculation formula of (sea) water content is as follows: (sea) water content = (W t -W0) / W t In order to evaluate the anti-swelling ability of the hydrogel, the polyurea supramolecular hydrogel obtained by soaking in water / simulated seawater for 24 hours at room temperature was further soaked in water / simulated seawater for 30 days. The hydrogel was taken out and weighed every 3 days to calculate its (sea) water content, and a (sea) water content-immersion time curve was drawn. The results are shown in Figure 2. Figure 3 、 Figure 4 shown.

[0083] (3) Determination of tensile properties of polyurea supramolecular hydrogel

[0084] Polyurea film strips, 6 cm long and 1 cm wide, were cut and soaked in water or simulated seawater at room temperature for 24 hours to produce hydrogel strips. Tensile properties were measured to obtain initial tensile strength and elongation at break. The hydrogel strips were soaked in water or simulated seawater for one and two weeks, and then re-measured for tensile properties. Tensile testing was performed using an electronic universal testing machine with a gauge length of 10 mm and a tensile rate of 30 mm / min. Three measurements were taken for each sample and the average was calculated. The results are shown in Table 2.

[0085] Table 1 Molecular weight and distribution of polyurea

[0086]

[0087] Table 2 Mechanical properties test results

[0088]

[0089] From the molecular weight and distribution of polyurea determined by gel permeation chromatography (GPC) in Table 1, it can be seen that linear polyurea was successfully synthesized.

[0090] Depend on Figure 3 and Figure 4 It can be seen that the polyurea supramolecular hydrogels obtained in Examples 1-4 remained unchanged in (sea) water content after being immersed in water / simulated seawater for 30 days, showing excellent anti-swelling properties.

[0091] From the mechanical property tests of the polyurea supramolecular hydrogels obtained in Examples 1-4 in Table 2, it can be seen that compared with the initial tensile properties, after immersion in water / simulated seawater for 1 to 2 weeks, the tensile strength retention rate of the polyurea supramolecular hydrogels obtained in the present invention is 80 to 97%, and the elongation at break retention rate is 70 to 97%, showing good mechanical property stability.

[0092] The above specific implementation methods are merely explanations of the present application and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel, characterized by: The following steps are involved: Adding a solvent to the polyetheramine, and then adding 77% to 100% of the total amount of diisocyanate, wherein the total amount of 77% to 100% does not include 100%, to carry out a prepolymerization reaction; then adding a chain extender and the remaining diisocyanate to carry out chain extension; cooling to room temperature to obtain a polyurea solution; Casting the polyurea solution into a film to obtain a polyurea film, then immersing the polyurea film in water or simulated seawater for 20-28 hours, and taking it out to obtain a polyurea supramolecular hydrogel; The polyetheramine is hydrophilic polyetheramine ED-900, the chain extender is oxalyl dihydrazide, and the diisocyanate is isophorone diisocyanate.

2. The method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel according to claim 1, characterized in that: The total amount of the diisocyanate is 2-2.6 times the molar amount of the polyetheramine.

3. The method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel according to claim 1, characterized in that: The prepolymerization reaction conditions are: under nitrogen atmosphere, at 28-35° C. for 1-1.5 hours.

4. The method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel according to claim 1, characterized in that: The amount of oxalyl dihydrazide added is 1-1.6 times the molar amount of the polyetheramine.

5. The method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel according to claim 1, characterized in that: The chain extension reaction conditions are: under nitrogen atmosphere, 50-55°C for 5-6 hours.

6. The method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel according to claim 1, characterized in that: The specific steps of casting the polyurea solution into a film are: pouring the polyurea solution into a mold and drying it to obtain a polyurea film.

7. The method for preparing a high-strength anti-swelling polyurea supramolecular hydrogel according to claim 1, characterized in that: The solvent is N,N-dimethylformamide.

8. The polyurea supramolecular hydrogel obtained according to the preparation method according to any one of claims 1 to 7.

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