Method for superfast polymerization of polyacrylic acid hydrogel

Abstract

The invention provides a preparation method for ultra-fast synthesis of polyacrylic acid (PAA) hydrogel. The method is mainly characterized in that acrylic acid is used as a monomer, Fe < 3 + > and N, N-methylene bisacrylamide are used as cross-linking agents, ammonium persulfate is used as an initiator, and Fe < 3 + > and MXenes synergistically catalyze ammonium persulfate to generate free radicals, so that second-level ultra-fast polymerization of PAA hydrogel is realized. The main principle is as follows: MXenes reduces Fe < 3 + > to generate Fe < 2 + >, Fe < 2 + > promotes ammonium persulfate to generate a sulfate free radical # imgabs0 # and is oxidized into Fe < 3 + >, and a Fe < 2 + > / Fe < 3 + > cyclic transformation process greatly accelerates generation of # imgabs1 #, so that acrylic acid chain growth is initiated, and rapid polymerization of PAA hydrogel within seconds is realized. The method has the characteristics of simplicity and rapidness, and the prepared PAA hydrogel has excellent mechanical property, self-repairing property and sensing property.

Description

Technical Field

[0001] The present invention relates to a preparation method of a super-fast polymerization polyacrylic acid hydrogel by using a free radical polymerization method, belonging to the technical field of material preparation. Background Art

[0002] In the context of the deep integration of intelligent medicine and flexible electronics technology, flexible wearable devices, as the core carriers for real-time health monitoring, are profoundly changing the traditional medical model. As a typical representative of biomimetic polymer materials, hydrogels, with their three-dimensional network structure, adjustable swelling degree, and mechanical properties similar to biological tissues, exhibit unique application potential in the directions of biomedicine, drug delivery systems, and tissue repair engineering. Especially in the field of wearable medical monitoring, hydrogel sensor devices show significant advantages over traditional metal electrodes due to their excellent flexibility and good interface adaptability.

[0003] The rapid polymerization of hydrogels can not only greatly shorten the preparation cycle but also is beneficial to maintaining the activity of biomolecules, providing an effective guarantee for the preparation of sensors with complex shapes and on-site diagnosis and treatment. However, existing photo-polymerized / chemically cross-linked hydrogels usually require curing times ranging from minutes to hours, making it difficult to meet the requirements of rapid manufacturing and immediate use. Therefore, there are still great challenges in preparing hydrogel-based flexible sensors with both rapid forming ability and excellent mechanical compliance. Summary of the Invention

[0004] The purpose of the present invention is to provide a simple preparation method of a super-fast polymerization PAA hydrogel, the main feature of which is using acrylic acid as a monomer, N,N-methylenebisacrylamide as a cross-linking agent, ferric chloride hexahydrate and MXenes as co-catalysts, and ammonium persulfate as an initiator, and realizing the super-fast polymerization of PAA hydrogel in seconds by using free radical polymerization.

[0005] The specific steps are as follows:

[0006] (1) Add 0.3 g of Ti3AlC2 powder to the mixed solution of LiF and hydrochloric acid in small amounts and multiple times. After treating it in a 35°C water bath for 24 h, centrifuge it at 8000 r min -1 for 5 min to remove the supernatant, and repeat centrifugation and washing multiple times until the pH of the supernatant is ≥6; then ultrasonicate the dispersion for 20 min under an argon protection atmosphere and let it stand for 15 min, repeat ultrasonication 4 - 6 times, and finally centrifuge it at 3500 r min -1 for 1 h to obtain a dispersion of lamellar Ti3C2T x nanosheets;

[0007] (2) Mix an appropriate amount of acrylic acid and deionized water, then add an appropriate amount of N,N-methylenebisacrylamide and FeCl3·6H2O, as well as a trace amount of MXenes dispersion, stir at room temperature for 10 minutes, and then add 168 mg of ammonium persulfate. The PAA hydrogel polymerizes instantaneously. It is characterized in that MXenes reduces Fe 3+ to generate Fe 2+ , Fe 2+ while promoting the generation of sulfate radicals and oxidizing itself to Fe 3+ , realizing the Fe 2+ / Fe 3+ cycle process to super-rapidly polymerize into a PAA hydrogel. Description of the Drawings

[0008] Figure 1 SEM pattern of the super-rapidly polymerized PAA hydrogel prepared in Example 6

[0009] Figure 2 XRD pattern of the super-rapidly polymerized PAA hydrogel prepared in Example 6

[0010] Figure 3 Stress-strain curve of the super-rapidly polymerized PAA hydrogel prepared in Example 6

[0011] Figure 4 FTIR spectrum of the super-rapidly polymerized PAA hydrogel prepared in Example 6

[0012] Specific Embodiments

[0013] The following non-limiting examples are used to further illustrate the implementation methods and effects:

[0014] Example 1

[0015] Add 0.3 g of Ti3AlC2 powder to the mixed solution of LiF and hydrochloric acid in small amounts and multiple times. After treating it in a 35°C water bath for 24 h, centrifuge for 5 min at 8000 r min -1 to remove the supernatant. Repeat centrifugation and washing multiple times until the pH of the supernatant is ≥ 6; then ultrasonicate the dispersion for 20 min and let it stand for 15 min under an argon protection atmosphere, repeat ultrasonication 4 - 6 times, and finally centrifuge for 1 h at 3500 r min -1 to obtain a dispersion of lamellar Ti3C2T x nanosheets (3 - 5 mg / mL);

[0016] Mix 2 mL of acrylic acid with 18 mL of deionized water in a small beaker. Subsequently, add 16.8 mg of N,N-methylenebisacrylamide, 168 mg of FeCl3·6H2O, and 0.1 mL of the MXenes dispersion. Stir at room temperature for 10 minutes, then add 168 mg of ammonium persulfate, and the PAA hydrogel polymerizes instantaneously.

[0017] Example 2

[0018] The MXenes dispersion was treated in the same manner as in Example 1. Mix 8 mL of acrylic acid with 12 mL of deionized water in a small beaker. Subsequently, add 16.8 mg of N,N-methylenebisacrylamide, 168 mg of FeCl3·6H2O, and 0.1 mL of the MXenes dispersion. Stir at room temperature for 10 minutes, then add 168 mg of ammonium persulfate, and the PAA hydrogel polymerizes instantaneously.

[0019] Example 3

[0020] The MXenes dispersion was treated in the same manner as in Example 1. Mix 8 mL of acrylic acid with 12 mL of deionized water in a small beaker. Subsequently, add 16.8 mg of N,N-methylenebisacrylamide, 168 mg of FeCl3·6H2O, and 0.3 mL of MXenes. Stir at room temperature for 10 minutes, then add 10 mg of ammonium persulfate, and the PAA hydrogel polymerizes instantaneously.

[0021] Example 4

[0022] The MXenes dispersion was treated in the same manner as in Example 1. Mix 8 mL of acrylic acid with 12 mL of deionized water in a small beaker. Subsequently, add 4.2 mg of N,N-methylenebisacrylamide, 168 mg of FeCl3·6H2O, and 1.0 mL of MXenes. Stir at room temperature for 10 minutes, then add 168 mg of ammonium persulfate, and the PAA hydrogel polymerizes instantaneously.

[0023] Example 5

[0024] The MXenes dispersion was treated in the same manner as in Example 1. Mix 8 mL of acrylic acid with 12 mL of deionized water. Subsequently, add 4.2 mg of N,N-methylenebisacrylamide, 42 mg of FeCl3·6H2O, and 168 mg of ammonium persulfate. Stir at room temperature for 10 minutes, then pour it into a petri dish with a diameter of Φ9 mm. Finally, add 0.5 mL of the MXenes dispersion, and the PAA hydrogel completes polymerization within 2 - 5 seconds.

[0025] Example 6

[0026] The dispersion treatment method of MXenes was the same as that in Example 1. 8 mL of acrylic acid and 12 mL of deionized water were mixed in a 50 mL small beaker. Subsequently, 16.8 mg of N,N-methylenebisacrylamide, 168 mg of FeCl3·6H2O, and 168 mg of ammonium persulfate were added. Finally, 0.5 mL of the MXenes dispersion was added, and the PAA hydrogel immediately polymerized. The SEM of the obtained PAA is shown in Figure 1 as shown, the XRD is shown in Figure 2 as shown, the stress-strain curve is shown in Figure 3 as shown, the FTIR spectrogram is as shown in Figure 4 as shown.

Claims

1. A method for super-fast polymerization of polyacrylic acid (PAA) hydrogel, characterized in that, Using acrylic acid as a monomer, Fe 3+ and N,N-methylenebisacrylamide as crosslinking agents, and ammonium persulfate as an initiator, Fe 3+ and MXenes synergistically catalyze ammonium persulfate to generate free radicals, thereby achieving the second-level ultra-fast polymerization of PAA hydrogel. The specific steps of this method are as follows: (1) Add 20 mL of HCl (12 M) to a centrifuge tube containing 1 g of LiF, stir to dissolve it, and then add 0.3 g of Ti3AlC2 powder in small portions. Place the entire system in a 35 °C water bath and stir for 24 h. After the reaction, centrifuge for 5 min at 8000 r min -1 to remove the supernatant. Repeat centrifugation and washing several times until the pH of the supernatant is ≥6. Ultrasonicate the dispersion for 20 min and then let it stand for 15 min under an argon protective atmosphere. Repeat sonication 4 - 6 times. Finally, centrifuge for 1 h at 3500 r min -1 to obtain a dispersion of lamellar Ti3C2T x nanosheets (3 - 5 mg / mL); (2) Mix acrylic acid and deionized water in a certain proportion, and then gradually add appropriate amounts of N,N'-methylenebisacrylamide, ferric chloride, and a small amount of MXenes dispersion. After stirring at room temperature for 5 to 10 minutes, add a certain amount of ammonium persulfate, and the PAA hydrogel polymerizes within seconds.

2. The method for preparing an ultra-fast polymerization polyacrylic acid hydrogel according to claim 1, wherein The mass ratio of acrylic acid monomer to water is: 1:9 to 2:

3.

3. The method for preparing a super-fast polymerized polyacrylic acid hydrogel according to claim 1, wherein The mass ratio of acrylic acid monomer to N,N'-methylenebisacrylamide is: 500:1 to 2000:

1.

4. The method for preparing a super-fast polymerized polyacrylic acid hydrogel according to claim 1, characterized in that The mass ratio of acrylic acid monomer to ferric chloride is: 50:1 to 200:

1.

5. A method for super-fast polymerization of polyacrylic acid hydrogel according to claim 1, characterized in that The mass ratio of acrylic acid monomer to ammonium persulfate is: 50:1 to 1200:

1.

6. A method for super-fast polymerization of polyacrylic acid hydrogel according to claim 1, characterized in that The addition amount of MXenes dispersion is: 0.1 to 1.0 mL.

7. A method for preparing an ultra-fast polymerized polyacrylic acid hydrogel according to claim 1, characterized in that, The addition order of ferric chloride, MXenes dispersion, and ammonium persulfate can be arbitrarily switched, and the PAA hydrogel can be obtained immediately as long as the three coexist.

8. A method for preparing a super-fast polymerization polyacrylic acid hydrogel according to claim 1, characterized in that The polymerization time of the PAA hydrogel is very short. Depending on the size of the hydrogel from Φ25mm to Φ95mm, the polymerization time ranges from 0.1s to 5s.

9. A method for preparing a super-fast polymerized polyacrylic acid hydrogel according to claim 1, characterized in that Its polymerization mechanism is that Fe 3+ and MXenes synergistically catalyze ammonium persulfate to generate free radicals, thus achieving the second-level ultra-fast polymerization of PAA hydrogel; this is because Ti 2+ on the surface of MXenes reduces Fe 3+ to generate Fe 2+ , and Fe 2+ and MXenes promote the generation of sulfate radicals from ammonium persulfate while being oxidized to Fe 3+ , and the cyclic transformation process of Fe 2+ / Fe 3+ greatly accelerates the generation of , thus initiating the growth of acrylic acid chains and achieving the rapid polymerization of PAA hydrogel within seconds.

10. The method for preparing an ultra-fast polymerized polyacrylic acid hydrogel according to claim 1, wherein The obtained PAA hydrogel material has a three-dimensional cross-linked network structure and good conductivity, and can be applied to fields such as flexible sensors.

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