A high-stretchability pillararene polypropylene hydrogel and a preparation method thereof

Abstract

This invention belongs to the field of supramolecular materials technology, and relates to a highly tensile columnar aromatic polypropylene hydrogel and its preparation method. A supramolecular polymer is obtained by mixing and reacting a columnar aromatic compound, a 4,4'-bipyridine compound, and polyethylene glycol. This supramolecular polymer is then added to an aqueous solution of acrylamide, sodium acrylate, and N,N-methylenebisacrylamide, and the final product is obtained by adding metal ions, an initiator, and a accelerator. The preparation method of the columnar aromatic supramolecular polymer network provided by this invention is simple, has mild reaction conditions, and is easy to implement. Adding the polymer to a propylene-based hydrogel can significantly improve its mechanical properties, resulting in superior mechanical and energy dissipation properties, and has great potential in the preparation of toughening agents.

Description

Technical Field

[0001] This invention belongs to the field of supramolecular materials technology and relates to a highly stretchable columnar aromatic polypropylene hydrogel and its preparation method. Background Technology

[0002] Acrylic-based hydrogels (acrylamide, acrylic acid, etc.) are widely used in biomedicine, water treatment, and other fields, typically exhibiting excellent water absorption and stability, and have been extensively studied by researchers. Xiong Lijun et al. from Wuhan University of Technology used acrylamide and acrylic acid as monomers, adding lithium diatomaceous earth to construct a network through electrostatic interaction, generating an interpenetrating double-network hydrogel with a maximum tensile stress of approximately 137 kPa. Li Chaoxia et al. from the University of Chinese Academy of Sciences added N-isopropylacrylamide to acrylamide, using polyvinyl alcohol diacrylate and polycaprolactone diacrylate as crosslinking agents to construct a network, generating an interpenetrating double-network hydrogel that, in addition to good mechanical properties, also possesses excellent temperature sensitivity. Wang Xiaohui et al. from South China University of Technology added lithium chloride (LiCl) and cellulose nanofibers to polyacrylamide hydrogels, preparing hydrogels with tensile strengths of 0.09-0.25 MPa and good freeze-thaw resistance and water retention. However, currently prepared acrylic-based hydrogels have low elongation at break after curing, and poor impact and puncture resistance, limiting their applications in many fields.

[0003] Therefore, synthesizing propylene-based hydrogels with good mechanical properties is the primary task for advancing the further development of this type of material. Summary of the Invention

[0004] This invention addresses the problems of low elongation at break and poor impact and puncture resistance of traditional propylene-based hydrogels after curing by proposing a novel high-strength columnar aromatic polypropylene hydrogel and its preparation method.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0006] A method for preparing a highly stretchable columnar aromatic polypropylene hydrogel involves mixing and reacting a columnar aromatic compound, a 4,4-bipyridine compound, and polyethylene glycol to obtain a supramolecular polymer. The supramolecular polymer is then added to an aqueous solution of acrylamide, sodium acrylate, and N,N-methylenebisacrylamide. The hydrogel is prepared by adding metal ions, an initiator, and an accelerator.

[0007] The method for preparing columnar aromatic supramolecular polymer networks provided by this invention is simple, has mild reaction conditions, and is easy to implement. Adding the polymer to a propylene-based hydrogel can greatly improve its mechanical properties, bringing superior mechanical and mechanical properties and energy dissipation to the material, and has great potential in the preparation of toughening agents.

[0008] The specific steps for preparing the above-mentioned highly tensile columnar aromatic polypropylene hydrogel are as follows:

[0009] (1) Add columnar aromatic compound a and 4,4-bipyridine compound b to water and mix at room temperature for 1.5-3 h to obtain quasi-rotaxane, wherein the structural formula of columnar aromatic compound a is:

[0010] ,

[0011] The structural formula of 4,4-bipyridine compound b is:

[0012] .

[0013] (2) Add bicyclic polyethylene glycol and tetracyclic polyethylene glycol to the quasi-rotaxane obtained in step (1) to obtain a mixture H. After complete dissolution, add lithium hydroxide to carry out a catalytic reaction to prepare a columnar [5] aromatic supramolecular polymer modified with sodium acetate.

[0014] (3) Acrylamide, sodium acrylate and N,N-methylenebisacrylamide are dissolved together in water, and the supramolecular polymer obtained in step (2) is added. Under the protection of an inert gas, a metal ion solution is added and mixed evenly to obtain a mixture P. Then an initiator and a promoter are added and allowed to stand to react to obtain a highly stretchable supramolecular hydrogel.

[0015] Preferably, in step (1), the molar ratio of columnar aromatic compound a to 4,4-bipyridine compound b is 1:1.

[0016] Preferably, in step (2), the mass fraction of quasi-rotaxane in the mixture H is 9-11%, and the molecular weights of the di-epoxy polyethylene glycol and the tetra-arm epoxy polyethylene glycol are 1000-20000; the molar ratio of the di-epoxy polyethylene glycol and the tetra-arm epoxy polyethylene glycol is (35-40):1.

[0017] Preferably, in step (3), the mass ratio of supramolecular polymer: acrylamide: sodium acrylate: N,N-methylenebisacrylamide is (0.2-2):(95-105):(95-105):(0.8-1.2). Excessive supramolecular polymer network will increase the dynamics of the hydrogel and decrease its tensile properties. The inert gas is nitrogen, and the metal ion solution is any one of copper nitrate solution, zinc nitrate solution, ferrous nitrate solution, cobalt nitrate solution, or nickel nitrate solution, with copper nitrate solution being the most preferred. The concentration of metal ions in the mixture P is 0.05-0.2 g / mL. Excessive addition of metal ions will make hydrogel formation difficult.

[0018] Preferably, the initiator in step (3) is ammonium persulfate or potassium persulfate, and the promoter is tetramethylethylenediamine.

[0019] The present invention also provides a highly tensile columnar aromatic polypropylene hydrogel prepared by the above method.

[0020] This invention uses a supramolecular polymer network of columnar aromatics modified with sodium acetate [5] as a toughening agent and combines it with propylene-based hydrogel through metal ions. Compared with traditional propylene-based hydrogel, the mechanical properties and energy dissipation are significantly improved. The addition of the columnar aromatic supramolecular polymer network can significantly improve the toughness and tensile properties of the original hydrogel, and promote maximum elongation and extensibility without sacrificing the mechanical strength of the polymer.

[0021] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0022] (1) This invention provides a columnar aromatic supramolecular polymer network with excellent performance, easy synthesis, and mild synthesis conditions. The host-guest interaction of columnar aromatics [5] and 4,4-bipyridine gives the supramolecular polymer network good dynamics. When added as a toughening agent to polypropylene-based hydrogels, the hydrogels have better mechanical properties and energy dissipation, and their maximum elongation and extensibility are greatly enhanced without sacrificing mechanical strength.

[0023] (2) The columnar aromatic supramolecular polymer network provided by the present invention has a tensile strength of 0.14 MPa and a maximum elongation of 1600% when it is in a suitable ratio with acrylamide and sodium acrylate. Attached Figure Description

[0024] Figure 1 This is a stretched image of the hydrogel prepared in Example 1.

[0025] Figure 2 Tensile stress-strain diagrams of hydrogels prepared by adding different metal ions.

[0026] Figure 3 Tensile stress-strain diagrams of hydrogels prepared with different amounts of added metal ions.

[0027] Figure 4 This is a cyclic tensile stress-strain diagram of the hydrogel.

[0028] Figure 5 This is a cyclic compressive stress-strain diagram of the hydrogel. Detailed Implementation

[0029] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below with reference to specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0030] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0031] Example 1

[0032] In this embodiment, columnar aromatic compound a is a columnar aromatic modified with sodium acetate [5], and its synthetic route is as follows:

[0033] .

[0034] 0.5 g of methoxy[5]arene (CAS No.: 1188423-16-6) was added to 50 mL of chloroform. Under nitrogen protection, 3.34 g of boron tribromide solution (mass fraction 99.9%) was slowly added. The reaction was stirred at room temperature for 72 h at a stirring rate of 200 rpm. After the reaction was completed, 50 mL of deionized water was added, and a precipitate was formed. The supernatant was discarded, and the precipitate was washed once with 0.5 mol / L hydrochloric acid solution and once with chloroform to obtain 0.35 g of white solid hydroxy[5]arene (CAS No.: 1187983-02-3), with a yield of 86%. The above operation was repeated to obtain sufficient hydroxy[5]arene for later use.

[0035] 0.5 g of hydroxyl column[5] aromatic hydrocarbon was weighed and dissolved in 30 mL of acetonitrile. 3 g of potassium carbonate was added and stirred for 1 h under a nitrogen atmosphere at a stirring rate of 200 rpm. Then, 0.034 g of sodium iodide and 2.79 g of ethyl bromoacetate were added. The mixture was heated under a nitrogen atmosphere at 90 °C and refluxed for 24 h. After the reaction was complete, the mixture was filtered and the filtrate was collected. The crude product was obtained by rotary evaporation. The crude product was separated by column chromatography (eluent: dichloromethane / ethyl acetate = 20:1, v / v) to obtain 0.72 g of ethyl acetate oxy-modified column[5] aromatic hydrocarbon (CAS No. 1235482-11-7), with a yield of 56.5%.

[0036] 0.3 g of ethyl acetate-modified columnar [5]arene was weighed and added to 40 mL of tetrahydrofuran, 20 mL of ethanol, and 20 mL of 40% sodium hydroxide solution. The mixture was heated under reflux at 70 °C for 10 h. After the reaction was completed, 20 mL of 0.5 mol / L hydrochloric acid was added and stirred thoroughly. The mixture was then acidified for 10 min. The precipitate was collected by filtration, washed twice with deionized water, and dried to obtain 0.18 g of ethyl acetate-modified columnar [5]arene (CAS No. 1235482-12-8), with a yield of 74%.

[0037] 0.15 g of acetoxy-modified columnar aromatic hydrocarbon [5] was weighed and added to 50 mL of deionized water. 0.04 g of sodium hydroxide was added, and the mixture was stirred at 200 rpm for 12 h at room temperature. The water was then evaporated under reduced pressure to obtain 0.15 g of sodium acetate-modified columnar aromatic hydrocarbon, with a yield of 89%. The structure of the synthesized sodium acetate-modified columnar aromatic hydrocarbon [5] was characterized: an appropriate amount of the final product was weighed into an NMR tube, dissolved in deuterated water, and tested using a nuclear magnetic resonance spectrometer at 25 °C. The spectrum showed no impurity peaks, indicating that the product reached a high purity. The NMR data are as follows: 1 H NMR (400MHz, D2O, 298K) δppm 6.77 (s, 10H), 4.50 (d, J =16.0Hz,10H),4.26(d, J = 16.1 Hz, 10H), 3.83 (s, 10H).

[0038] The 4,4-bipyridine derivative in this embodiment was synthesized using the following route:

[0039] .

[0040] 1.95 g of 1,6-dibromohexane and 0.91 g of potassium thioacetate were added to 50 mL of dry tetrahydrofuran. The mixture was heated under reflux at 60 °C for 12 h. After the reaction was complete, the mixture was filtered, and the solution was evaporated to dryness to obtain the crude product. The crude product was subjected to column chromatography (eluent: petroleum ether / ethyl acetate = 9:1, v / v) to obtain 0.9 g of pure thioacetic acid bromhexane (CAS No. 479072-66-7), with a yield of 49%. This step was repeated to obtain sufficient thioacetic acid bromhexane for later use.

[0041] 1 g of thioacetic acid bromhexane and 0.26 g of 4,4-bipyridine (CAS: 553-26-4) were weighed and mixed in 100 mL of acetonitrile. The mixture was reacted at 80 °C for 96 h. After the reaction was completed, the mixture was evaporated to dryness, dissolved in 5 mL of methanol, and then 15 mL of diethyl ether was added. A solid precipitated out. The solid was filtered to obtain 0.79 g of thioacetic acid 4,4-bipyridine (CAS No. 871028-80-7), with a yield of 74%.

[0042] 0.5 g of thioacetic acid-modified 4,4-bipyridine was dissolved in 50 mL of methanol. Under nitrogen protection, 1.2 g of acetyl chloride was added dropwise at -78 °C (dropping time was 10-15 s). After the addition was complete, the reaction was maintained at -78 °C for 10 min, and then the temperature was restored to room temperature and the reaction was continued for 3 h. After the reaction was completed, the solvent was evaporated to obtain 0.4 g of yellow solid mercaptohexane-modified 4,4-bipyridine, with a yield of 92%.

[0043] The structure of the synthesized mercaptohexane-modified 4,4-bipyridine was characterized. An appropriate amount of the final product was weighed into an NMR tube, dissolved in deuterated methanol, and analyzed using an NMR spectrometer at 25°C. The obtained spectrum showed no impurity peaks, confirming the high purity of the product. The NMR data are as follows: 1 H NMR (400 MHz, CD3OD, 298K)δ ppm 9.34 – 9.27 (m,4H), 8.70 (d, J = 6.3 Hz, 4H), 4.77 (t, J = 7.6 Hz, 4H), 3.35 (s, 4H), 2.52 (tt, J = 7.1, 4H), 2.12 (p, J = 7.6 Hz, 4H), 1.72 – 1.59 (m, 4H), 1.59 – 1.40 (m, 4H).

[0044] 0.15 g of acetoxy-modified columnar aromatic [5] and 0.056 g of mercaptohexane-modified 4,4-bipyridine were weighed and added to 60 mL of deionized water. The mixture was stirred at room temperature for 2 h to obtain quasi-rotaxane. An appropriate amount of quasi-rotaxane product was placed in an NMR tube, dissolved in deuterated water, and tested using a nuclear magnetic resonance spectrometer at 25 °C. The obtained NMR data are as follows: 1 ¹H NMR (400MHz, D₂O, 298K) δppm 8.58 (s, 4H), 8.38 (s, 4H), 7.09 (s, 10H), 4.34 (s, 20H), 3.91 (s, 10H), 3.35 (s, 4H), 2.07 (s, 4H), 1.05 (s, 4H), 0.79 (s, 8H), 0.62 (s, 4H). The spectrum showed no impurity peaks, indicating that the product achieved high purity.

[0045] Add 1.9g of bicyclic epoxy polyethylene glycol (Mn=20000) and 0.2g of tetracyclic epoxy polyethylene glycol (Mn=20000) to the obtained quasi-rotaxane. After complete dissolution, add 0.001g of lithium hydroxide and catalyze the reaction for 2 hours to form a supramolecular polymer network mixture for later use.

[0046] 1g of acrylamide, 1g of sodium acrylate, and 0.01g of N,N-methylenebisacrylamide were dissolved together in 6mL of deionized water. 0.03g of a supramolecular polymer network mixture was added. Under nitrogen protection, 5μL of 0.1g / mL copper nitrate solution was added. After mixing thoroughly, 0.005g of ammonium persulfate initiator and 0.002g of tetramethylethylenediamine accelerator were added. The mixture was then transferred to a PTFE mold and allowed to stand for 30min to obtain a highly stretchable supramolecular hydrogel.

[0047] 1. Tensile test

[0048] The highly stretchable supramolecular hydrogel obtained in this embodiment was subjected to a tensile test. At room temperature, a hydrogel sample measuring 4 cm in length, 1 cm in width, and 0.3 cm in thickness was placed in the fixture of a universal testing machine, and the stretching rate was set to 10 mm / min. The test results showed that the supramolecular hydrogel could be stretched more than 10 times its original length. The actual sample is shown below. Figure 1 As shown.

[0049] 2. Tensile force and strain

[0050] Experimental Procedure: The copper nitrate solution in Example 1 was replaced with zinc nitrate solution, nickel nitrate solution, cobalt nitrate solution, and ferrous nitrate solution, each with a concentration of 0.1 g / mL, respectively. All other conditions remained unchanged. The resulting hydrogels were subjected to tensile testing in a universal testing machine under the same conditions. Results are as follows: Figure 2 As shown.

[0051] The amount of supramolecular polymer network mixture added in Example 1 was adjusted from 0.03 g (1.5 wt%, Example 1) to 0 g (no addition), 0.004 g (0.2 wt%), 0.01 g (0.5 wt%), 0.02 g (1 wt%), and 0.06 g (2 wt%), respectively. Keeping other conditions unchanged, the resulting hydrogels were subjected to tensile testing in a universal testing machine under the same conditions. The results are as follows: Figure 3 As shown.

[0052] from Figure 2 and Figure 3 As can be seen, the tensile stress of hydrogels prepared by adding different metal cation solutions and different mass fractions of supramolecular polymer network mixtures changes. Different metal cations can all increase the tensile length of the original polypropylene-based hydrogel, with copper ions showing the best effect. Adding different mass fractions of supramolecular polymer network mixtures significantly increases the maximum elongation of the original polypropylene-based hydrogel, and the strain of the hydrogel also increases with increasing mass fraction. However, adding excessive amounts of supramolecular polymer network mixtures increases its brittleness and reduces its tensile effect.

[0053] 3. Cyclic tensile and compression test

[0054] The hydrogel prepared in Example 1 was subjected to cyclic tensile testing at a tensile rate of 10 mm / min and a tensile strain set to 1000% of the raw material. The results are as follows: Figure 4 As shown, the hydrogel exhibits good cyclic tensile properties. Cyclic compression tests were performed on the hydrogel prepared in Example 1, with a compression rate of 5 mm / min and a maximum compressive strain of 80% of the original material. The results are as follows. Figure 5 As shown in the figure, the stress remained essentially unchanged after five cycles of compression. This indicates that the addition of the supramolecular polymer network did indeed play a dissipation role, increasing the mechanical properties of the hydrogel.

[0055] 4. Stability

[0056] The hydrogel prepared in Example 1 was subjected to a tensile test after being left for 2 days, and its mechanical properties showed almost no decrease. This indicates that the hydrogel prepared in this invention has good stability.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a highly stretchable columnar aromatic polypropylene hydrogel, characterized in that, The steps are as follows: (1) Add columnar aromatic compound a and 4,4-bipyridine compound b to water and mix at room temperature for 1.5-3 h to obtain quasi-rotaxane, wherein The structural formula of columnar aromatic compound a is: ， The structural formula of 4,4-bipyridine compound b is: ； (2) Add bi-epoxy polyethylene glycol and four-arm epoxy polyethylene glycol to the quasi-rotaxane obtained in step (1) to obtain a mixture H. After complete dissolution, add lithium hydroxide to carry out a catalytic reaction to obtain a supramolecular polymer. (3) Acrylamide, sodium acrylate and N,N-methylenebisacrylamide are dissolved together in water, and the supramolecular polymer obtained in step (2) is added. Under the protection of an inert gas, a metal ion solution is added and mixed evenly to obtain a mixture P. Then an initiator and a promoter are added and allowed to stand to react to obtain a highly stretchable supramolecular hydrogel.

2. The method for preparing the highly tensile columnar aromatic polypropylene hydrogel according to claim 1, characterized in that, In step (1), the molar ratio of columnar aromatic compound a to 4,4-bipyridine compound b is 1:

1.

3. The method for preparing the highly tensile columnar aromatic polypropylene hydrogel according to claim 1, characterized in that, In step (2), the mass fraction of quasi-rotaxane in mixture H is 9-11%, and the molecular weights of the di-epoxy polyethylene glycol and the tetra-arm epoxy polyethylene glycol are 1000-20000; the molar ratio of the di-epoxy polyethylene glycol and the tetra-arm epoxy polyethylene glycol is (35-40):

1.

4. The method for preparing the highly tensile columnar aromatic polypropylene hydrogel according to claim 1, characterized in that, In step (3), the mass ratio of supramolecular polymer: acrylamide: sodium acrylate: N,N-methylenebisacrylamide is (0.2-2):(90-110):(90-110):(0.8-1.2). The inert gas is nitrogen. The metal ion solution is any one of copper nitrate solution, zinc nitrate solution, ferrous nitrate solution, cobalt nitrate solution, and nickel nitrate solution. The concentration of metal ions in the mixed solution P is 0.05-0.2 g / mL.

5. The method for preparing the highly tensile columnar aromatic polypropylene hydrogel according to claim 1, characterized in that, In step (3), the initiator is ammonium persulfate or potassium persulfate, and the promoter is tetramethylethylenediamine.

6. The highly tensile columnar aromatic polypropylene hydrogel prepared by any one of claims 1-5.

Images