A method for the rapid initiation of radical polymerization of hydrophilic monomers to produce hydrogels

Abstract

The application discloses a method for preparing hydrogel by rapidly initiating radical polymerization of hydrophilic monomers, and belongs to the technical field of hydrogel preparation. The method comprises the following steps: (1) uniformly mixing hydrophilic monomers with water, adding a mixed dispersion liquid of MXene and iron-based metal nanozyme material, stirring, and then obtaining a precursor solution after ultrasonic treatment; (2) adding a persulfate solution to the precursor solution, and then mixing to obtain the product. The application constructs a cascade catalytic system based on MXene and iron-based metal nanozyme. MXene can not only react with peroxide, but also promote the circulation of Fe 3+ / Fe 2+ in the iron-based metal nanozyme. The two synergistically catalyze the rapid decomposition of peroxide and initiate radical polymerization. At the same time, by utilizing various functional groups on the surface, MXene / iron-based metal nanozyme also participates in the structure bonding of the hydrogel, continuously and efficiently initiates the rapid polymerization and crosslinking of the hydrophilic monomers under mild conditions, and forms the hydrogel.

Description

Technical Field

[0001] This invention relates to the field of hydrogel preparation technology, and more specifically to a method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels. Background Technology

[0002] Free radical polymerization and crosslinking are commonly used methods for hydrogel design and synthesis. Currently, free radical polymerization mainly employs two pathways: one is the direct polymerization of one or more low-molecular-weight olefin monomers in the presence of a crosslinking agent; the other is to first convert a water-soluble polymer that is originally non-polymerizable into a derivative containing polymerizable reactive groups, followed by crosslinking copolymerization. Acrylic acid, acrylamide, and N,N-dimethylacrylamide are common hydrophilic olefin monomers widely used in the preparation of functional hydrogels. These hydrophilic monomers are generally polymerized by adding an initiator to generate free radicals, followed by elementary reactions such as chain growth, chain transfer, and chain termination.

[0003] Persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate are common free radical polymerization initiators, but their decomposition rate (kJ / mol) at room temperature is low. d The free radical polymerization time is relatively low, making it difficult to decompose rapidly. Factors such as the decomposition rate and conditions of persulfate directly affect the time required for free radical polymerization, thus determining the final hydrogel formation time. To increase the polymerization rate of monomers, external energy input is typically required, including light, heat, radiation, and plasma. However, this increases manufacturing costs and also raises requirements for additional equipment, facilities, and safety during the polymerization process, posing challenges to large-scale production.

[0004] Introducing catalysts to lower the energy barrier for persulfate decomposition is a more convenient and suitable method for large-scale production of polymer-based hydrogels. Currently developed persulfate decomposition catalysts include N,N'-methylenebisacrylamide (TMEDA) and liquid metal nanoparticles. Although these catalysts have solved the dependence of hydrophilic monomer radical polymerization on external energy sources to some extent, they are still limited by factors such as low catalytic efficiency and poor biocompatibility. At the same time, some catalysts have problems such as poor compatibility with the internal components of the hydrogel, which may affect the various properties of the hydrogel and even lead to internal defects in the crosslinking network.

[0005] Therefore, developing a simple, efficient, and environmentally friendly catalytic system for initiating the rapid polymerization of hydrophilic monomers, while simultaneously replacing traditional crosslinking agents and enhancing hydrogel properties, will provide a new approach for the development and production of functional hydrogels. Such a catalytic system holds promise for improving hydrogel performance and playing a significant role in environmental and industrial applications. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels, thereby solving the problems of slow free radical-initiated monomer polymerization and dependence on external energy in the preparation of existing multifunctional hydrogels.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0008] (1) Mix the hydrophilic monomer with water evenly, add the mixed dispersion of MXene and iron-based metal nanoenzyme material, stir and sonicate to obtain the precursor solution;

[0009] (2) Add persulfate solution to the precursor solution obtained in step (1), mix well and then prepare the product.

[0010] The beneficial effects of this invention are as follows: This invention develops a multifunctional MXene / iron-based metal nanozyme cascade catalytic system. Utilizing the reducing properties of MXene itself and the highly efficient catalytic ability of iron-based metal nanozymes, MXene first initiates the decomposition of some persulfates and simultaneously initiates and accelerates the internal Fe content of the iron-based metal nanozymes. 3+ / Fe 2+ The cyclic process, and the use of Fe 2+ A Fenton-like system, interacting with peroxides to generate advanced oxidation processes, accelerates the decomposition of peroxides and the generation of free radicals. The synergistic effect of MXene / iron-based metal nanozymes addresses the challenges posed by rapid iron depletion, low electron transport rates, and Fe... 3+ / Fe 2+ The problem of low redox cycle kinetics is addressed by significantly improving catalytic efficiency to initiate the rapid polymerization of hydrophilic monomers to form hydrogels; simultaneously, Ti3C2T is utilized. X MXene and iron-based metal nanozymes have multiple functional groups on their surface, such as -OH, -O and -NH2, which form a three-dimensional hydrogel crosslinking network with hydrophilic polymer chains through multiple hydrogen bonding interactions, thus avoiding the introduction of traditional toxic crosslinking agents.

[0011] Furthermore, the hydrophilic monomer in step (1) includes at least one of acrylic acid, acrylamide, N,N-dimethylacrylamide and N-isopropylacrylamide.

[0012] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: the MXene / Fe-MIL-88NH2 cascade catalytic system provided by the present invention can be applied to the preparation of hydrogels with a variety of hydrophilic monomers and has universality.

[0013] Furthermore, in step (1), the mass ratio of hydrophilic monomer to water is 1:3-1:1.

[0014] Furthermore, in step (1), the total concentration of the mixed dispersion of MXene and iron-based metal nanozyme is 5-10 mg / mL; the total mass of MXene and iron-based metal nanozyme is 0.5%-1.0% of the mass of the hydrophilic monomer.

[0015] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: the present invention only requires about 0.5%-1.0% of the material in total monomer mass to initiate the reaction, and at the same time, it can prepare hydrogels in large quantities without the introduction of additional crosslinking agents, thereby reducing the preparation cost.

[0016] Furthermore, in step (1), MXene is Ti2C3T x MXene, an iron-based metal nanozyme material, is at least one of Fe-MIL-88NH2 and Fe3O4, with Fe-MIL-88NH2 being more preferred. Ti2C3T x The mass ratio of MXene to iron-based metal nanozymes is 30:1-100:1.

[0017] Furthermore, Ti2C3T x The mass ratio of MXene to Fe-MIL-88NH2 is 67:1.

[0018] Furthermore, in step (1), the stirring speed is 200-500 rpm and the time is 5-20 min.

[0019] Furthermore, in step (1), the power of the ultrasound is 50-200W and the time is 5-20min.

[0020] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: the reaction conditions of the present invention are mild, the entire reaction process is carried out at room temperature, which can save energy and avoid potential safety problems.

[0021] Further, in step (2), the peroxide solution is at least one of sodium persulfate, ammonium persulfate, potassium persulfate and hydrogen peroxide solution, with a concentration of 100-200 mg / mL, and the volume ratio of the peroxide solution to the precursor solution is 1:5-1:20; the reaction time is 10-900 s.

[0022] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: the MXene / Fe-MIL-88NH2 cascade catalytic system provided by the present invention can be applied to a variety of initiators and has universality.

[0023] The hydrogels prepared by the above-described method for rapidly initiating hydrophilic monomer free radical polymerization are as follows.

[0024] The present invention has the following beneficial effects:

[0025] (1) The method of the present invention is convenient and fast, and can quickly catalyze the decomposition of persulfate. It can initiate the rapid polymerization of hydrophilic monomers into gel in one step without the introduction of other crosslinking agents, and can form hydrogels in as little as 13 seconds.

[0026] (2)Ti2C3T x MXene and Fe-MIL-88NH2 form a highly efficient cascade catalytic system, with some low-valent titanium (Ti) present in MXene. 3+ Ti 2+ It can undergo a redox reaction with persulfate to produce ·SO4. - Meanwhile, some low-valent titanium can also react with Fe in Fe-MIL-88NH2. 3+ The reaction produces Fe 2+ Fe 2+ Can interact with S2O8 2- This forms a highly oxidized Fenton-like system, generating -SO4. - and Fe 3+ Further promote the formation of Fe 3+ / Fe 2+ Cyclic, rapid catalysis of S2O8 2- Decomposition generates a large amount of SO4 - Subsequently, SO4 - It reacts with water to form ·OH, which initiates the polymerization of hydrophilic monomers into a gel.

[0027] (3) MXene not only provides the low-valent titanium ions required for cycling, but its large specific surface area and excellent conductivity also provide a channel for the efficient conduction of redox reactions. The special porous structure of Fe-MIL-88NH2 allows Fe to pass through the redox reaction. 3+ / Fe 2+ Confining the catalytic space within the structure increases the contact area with persulfate, significantly improving catalytic efficiency. The rapid polymerization to form a hydrogel is impossible without any one of these components.

[0028] (4) Thanks to the abundant functional groups on the surface of MXene and Fe-MIL-88NH2, such as -OH, -O and -NH2, MXene and Fe-MIL-88NH2 also act as crosslinking agents in the gelation system. Through the multiple hydrogen bonding between the surface functional groups and the hydrophilic monomers, they promote the formation of hydrogel network structure.

[0029] (5) The entire gelation process of this invention is carried out at room temperature, which can save energy; the catalytic efficiency is high and the reaction speed is fast, which can save time and improve the efficiency of preparing hydrogels; only about 0.5%-1.0% of the total mass of the monomer is needed to initiate the reaction, and at the same time, no additional crosslinking agent is needed to prepare hydrogels in large quantities, which reduces the preparation cost. Furthermore, no toxic reagents are needed, which makes the hydrogels prepared by this method have good biological safety. Attached Figure Description

[0030] Figure 1 To obtain Ti2C3T x Morphological characterization diagrams of MXene and Fe-MIL-88NH2, where a represents Ti2C3T x b is the scanning electron microscope (SEM) and transmission electron microscope (TEM) images of MXene.

[0031] Figure 2 To obtain Ti2C3T x X-ray photoelectron spectra of MXene and Fe-MIL-88NH2, where a represents Ti2C3T x X-ray photoelectron spectrum of MXene, bd are Ti2C3T in sequence. x The deconvolutioned Ti 2p, O 1s, C 1s orbital spectra of MXene, e is the X-ray photoelectron spectrum of Fe-MIL-88NH2, and f is the deconvolutioned Fe 2p orbital spectrum of Fe-MIL-88NH2.

[0032] Figure 3 The diagram illustrates the gelation mechanism, where a is the electron paramagnetic resonance spectrum of different systems reacting with persulfate, and b is the UV-Vis spectrophotometric spectrum of the products of the cascade catalytic system reacting with persulfate.

[0033] Figure 4 This diagram illustrates the rapid gelation mechanism of hydrogels, along with temperature and gelation time graphs for different systems. Figure a shows the cascaded catalytic rapid gelation mechanism and schematic diagram of hydrogels, while figures b and c represent MXene / S₂O₈ systems. 2- The system is related to MXene / Fe-MIL-88NH2 / S2O8 2- Temperature variation during the gelation process of the system, where d represents the gelation rate of the system under different MXene contents and different Fe-MIL-88NH2 contents;

[0034] Figure 5 The diagram shows the gelation process of Examples 1-7 and Comparative Example 4, where a is Example 1, b is Example 2, c is Example 3, d is Example 4, e is Example 5, f is Example 6, g is Example 7, and h is Comparative Example 1. Detailed Implementation

[0035] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0036] Example 1:

[0037] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0038] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0039] Ti2C3T was synthesized by specifically etching the MAX phase Ti2AlC3 using the minimum layer strength exfoliation (MILD) method. x MXene was prepared as follows: 1 g of LiF was dispersed in 20 mL of concentrated hydrochloric acid solution (9 mol / L) and reacted at 35 °C for 24 h. The generated HF specifically etched away the Al atomic layer of the Ti2AlC3 MAX material. After further sonication and centrifugation, Ti2C3T was obtained. x The MXene solution was then freeze-dried to obtain flake-like Ti2C3T with a metallic luster. x MXene, after sealing, should be stored at 4°C for later use.

[0040] (2) Synthesis of Fe-MIL-88NH2, a metal-organic framework (MOF) material with an octahedral structure

[0041] Fe-MIL-88NH2 was synthesized using a solvothermal method. The specific process is as follows: 0.2507 g NH2-BDC (1.3838 mmol) and 0.3743 g FeCl3·6H2O (1.3838 mmol) were dissolved in 30 mL DMF, stirred vigorously, and reacted at 120 °C for 12 h. After washing and vacuum drying at 40 °C, the product was obtained and stored in a light-proof sealed container for later use.

[0042] (3) Rapid preparation of hydrophilic polymer-based hydrogels

[0043] Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 30mg of Ti2C3T xMXene and 0.45 mg Fe-MIL-88NH2 were uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a mixed dispersion. The mixed dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added and quickly mixed until homogeneous. The mixture was then poured into a mold and reacted for 43 s to obtain a hydrogel.

[0044] Example 2:

[0045] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0046] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0047] The synthesis method is the same as in Example 1.

[0048] (2) Synthesis of Fe-MIL-88NH2, a metal-organic framework (MOF) material with an octahedral structure

[0049] The synthesis method is the same as in Example 1.

[0050] (3) Rapid preparation of hydrophilic polymer-based hydrogels

[0051] Take 3g of acrylamide and 4.5mL of deionized water to prepare mixture I; then weigh 30mg of Ti2C3T x MXene and 0.45 mg Fe-MIL-88NH2 were uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a mixed dispersion. The mixed dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added, and the mixture was quickly mixed and poured into a mold. The reaction was allowed to proceed for 73 s to obtain a hydrogel.

[0052] Example 3:

[0053] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0054] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0055] The synthesis method is the same as in Example 1.

[0056] (2) Synthesis of Fe-MIL-88NH2, a metal-organic framework (MOF) material with an octahedral structure

[0057] The synthesis method is the same as in Example 1.

[0058] (3) Rapid preparation of hydrophilic polymer-based hydrogels

[0059] Take 3g of N,N-dimethylacrylamide and 4.5mL of deionized water to prepare mixture I; then weigh 30mg of Ti₂C₃T x MXene and 0.45 mg Fe-MIL-88NH2 were uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a mixed dispersion. The mixed dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added and quickly mixed until homogeneous. The mixture was then poured into a mold and reacted for 767 s to obtain a hydrogel.

[0060] Example 4:

[0061] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0062] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0063] The synthesis method is the same as in Example 1.

[0064] (2) Synthesis of Fe-MIL-88NH2, a metal-organic framework (MOF) material with an octahedral structure

[0065] The synthesis method is the same as in Example 1.

[0066] (3) Rapid preparation of hydrophilic polymer-based hydrogels

[0067] Prepare solution I by mixing 1 g of N-isopropylacrylamide with 2.25 mL of deionized water; then weigh 30 mg of Ti₂C₃T. x MXene and 0.45 mg Fe-MIL-88NH2 were uniformly dispersed in 2.75 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a mixed dispersion. The mixed dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added and quickly mixed until homogeneous. The mixture was then poured into a mold and reacted for 833 s to obtain a hydrogel.

[0068] Example 5:

[0069] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0070] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0071] The synthesis method is the same as in Example 1.

[0072] (2) Synthesis of Fe3O4 iron-based metal nanozymes

[0073] A three-necked flask containing 100 mL of deionized water was slowly heated to 50 °C. Then, under vigorous mechanical stirring, 2.448 g of FeCl3·6H2O, 1.012 g of FeCl2·4H2O, 35 mL of NH3-H2O, and 3.3 g of trisodium citrate dihydrate were added sequentially, and the mixture was maintained at 80 °C for 30 minutes. The reaction was carried out under nitrogen (N2) protection. The reaction product was then washed with deionized water until the pH of the supernatant was neutral. Finally, the final product was dispersed in deionized water and stored at 4 °C.

[0074] (3) Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 30mg of Ti2C3T x MXene and 0.45 mg Fe3O4 iron-based metal nanozyme were uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a mixed dispersion. The mixed dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added, and the mixture was quickly mixed and poured into a mold to react and obtain a hydrogel.

[0075] Example 6:

[0076] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0077] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0078] The synthesis method is the same as in Example 1.

[0079] (2) Synthesis of Fe-MIL-88NH2, a metal-organic framework (MOF) material with an octahedral structure

[0080] The synthesis method is the same as in Example 1.

[0081] (3) Rapid preparation of hydrophilic polymer-based hydrogels

[0082] Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 30mg of Ti2C3T xMXene and 0.45 mg Fe-MIL-88NH2 were uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a mixed dispersion. The mixed dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL ammonium persulfate solution was added and quickly mixed evenly. The mixture was then poured into a mold and reacted for 56 s to obtain a hydrogel.

[0083] Example 7:

[0084] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0085] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0086] The synthesis method is the same as in Example 1.

[0087] (2) Synthesis of Fe-MIL-88NH2, a metal-organic framework (MOF) material with an octahedral structure

[0088] The synthesis method is the same as in Example 1.

[0089] (3) Rapid preparation of hydrophilic polymer-based hydrogels

[0090] Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 30mg of Ti2C3T x MXene and 0.45 mg Fe-MIL-88NH2 were uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a mixed dispersion. The mixed dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL potassium persulfate solution was added, and the mixture was quickly mixed and poured into a mold. The reaction was allowed to proceed for 56 s to obtain a hydrogel.

[0091] Example 8:

[0092] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0093] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0094] The synthesis method is the same as in Example 1.

[0095] (2) Synthesis of Fe-MIL-88NH2, a metal-organic framework (MOF) material with an octahedral structure

[0096] The synthesis method is the same as in Example 1.

[0097] (3) Rapid preparation of hydrophilic polymer-based hydrogels

[0098] Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 30mg of Ti2C3T x MXene and 0.45 mg Fe-MIL-88NH2 were uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a mixed dispersion. The mixed dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 3% hydrogen peroxide solution was added, and the mixture was quickly mixed and poured into a mold. The reaction was allowed to proceed for 862 s to obtain a hydrogel.

[0099] Example 9:

[0100] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0101] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0102] The synthesis method is the same as in Example 1.

[0103] (2) Rapid preparation of hydrophilic polymer-based hydrogels

[0104] Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 30mg of Ti2C3T x MXene and 0.3 mg Fe-MIL-88NH2 were uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a dispersion. The dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added and quickly mixed until homogeneous. The mixture was then poured into a mold and reacted for 60 s to obtain a hydrogel.

[0105] Example 10:

[0106] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0107] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0108] The synthesis method is the same as in Example 1.

[0109] (2) Rapid preparation of hydrophilic polymer-based hydrogels

[0110] Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 30mg of Ti2C3T x MXene and 0.6 mg Fe-MIL-88NH2 were uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a dispersion. The dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added and quickly mixed. The mixture was then poured into a mold and reacted for 40 s to obtain a hydrogel.

[0111] Example 11:

[0112] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0113] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0114] The synthesis method is the same as in Example 1.

[0115] (2) Rapid preparation of hydrophilic polymer-based hydrogels

[0116] Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 30mg of Ti2C3T x MXene and 0.9 mg Fe-MIL-88NH2 were uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a dispersion. The dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added and quickly mixed. The mixture was then poured into a mold and reacted for 25 s to obtain a hydrogel.

[0117] Example 12:

[0118] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0119] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0120] The synthesis method is the same as in Example 1.

[0121] (2) Rapid preparation of hydrophilic polymer-based hydrogels

[0122] Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 45mg of Ti2C3T x MXene and 0.9 mg Fe-MIL-88NH2 were uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min. Then, the mixture was sonicated at 100 W for 10 min to obtain a dispersion. The dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added and quickly mixed. The mixture was then poured into a mold and reacted for 13 s to obtain a hydrogel.

[0123] Comparative Example 1:

[0124] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0125] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0126] The synthesis method is the same as in Example 1.

[0127] (2) Rapid preparation of hydrophilic polymer-based hydrogels

[0128] Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 15mg of Ti2C3T x MXene was uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min, followed by ultrasonic treatment at 100 W for 10 min to obtain a dispersion. The dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added, and the mixture was quickly mixed and poured into a mold. The reaction was carried out for 949 s to obtain a hydrogel.

[0129] Comparative Example 2:

[0130] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0131] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0132] The synthesis method is the same as in Example 1.

[0133] (2) Rapid preparation of hydrophilic polymer-based hydrogels

[0134] Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 30mg of Ti2C3T xMXene was uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min, followed by ultrasonic treatment at 100 W for 10 min to obtain a dispersion. The dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added, and the mixture was quickly mixed and poured into a mold. The reaction was allowed to proceed for 615 s to obtain a hydrogel.

[0135] Comparative Example 3:

[0136] A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels includes the following steps:

[0137] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0138] The synthesis method is the same as in Example 1.

[0139] (2) Rapid preparation of hydrophilic polymer-based hydrogels

[0140] Take 3g of acrylic acid and 4.5mL of deionized water and prepare mixture I; then weigh 45mg of Ti2C3T x MXene was uniformly dispersed in 5.5 mL of deionized water and stirred at 300 rpm for 10 min, followed by ultrasonic treatment at 100 W for 10 min to obtain a dispersion. The dispersion was then added to mixture I to obtain a precursor solution. Finally, 1 mL of 120 mg / mL sodium persulfate solution was added, and the mixture was quickly mixed and poured into a mold. The reaction was allowed to proceed for 290 s to obtain a hydrogel.

[0141] Experimental Example 1: Ti2C3T x Characterization of MXene and Fe-MIL-88NH2

[0142] (1) The Ti2C3T prepared by scanning electron microscopy and transmission electron microscopy were analyzed. x MXene and Fe-MIL-88NH2 were used to characterize the surface morphology.

[0143] Experimental results are as follows Figure 1 As shown.

[0144] like Figure 1 As shown in Figure a, the MXene surface exhibits a distinct wrinkled structure, which provides a larger specific surface area and reaction sites for the catalytic reaction. Figure 1 As shown in Figure b, Fe-MIL-88NH2 nanoparticles have a typical octahedral structure and also have a large specific surface area, which improves reaction efficiency.

[0145] (2) The crystal structures of MXene and Fe-MIL-88NH2 were characterized by X-ray diffraction (XRD).

[0146] like Figure 1 The XRD patterns of c, d, MXene and Fe-MIL-88NH2 are consistent with the major peak positions of previously reported MXene and Fe-MIL-88NH2 materials, demonstrating the successful preparation of both materials.

[0147] (3) X-ray photoelectron spectroscopy (XPS) was used to analyze the prepared Ti2C3T x The valence states of major elements in MXene and Fe-MIL-88NH2 were characterized.

[0148] Experimental results are as follows Figure 2 As shown.

[0149] like Figure 2 Figure a-b in the diagram, Ti2C3T x MXene mainly contains elements such as C, Ti, O, F, and Cl. Among them, Ti exists in several low valence states, including Ti... 2+ and Ti 3+ This gives MXene strong reducing properties, allowing it to react directly with persulfates under certain conditions to generate free radicals. Meanwhile, as... Figure 2 Figures c-d in the diagram show that chemical bonds representing Ti-O, Ti-OH, and Ti-C were also observed in the deconvolutioned O1s and C1s orbital spectra of MXene, which proves the multivalent state of Ti in MXene. Figure 2 In the e-f diagram, Fe-MIL-88NH2 mainly contains Fe, N, C, and O, with Fe mainly in the form of Fe2+. 3+ Therefore, the low-valent Ti in MXene can react with it to generate Fe. 2+ Fe 2+ It has strong reducing properties and can react with S2O8. 2- This forms a highly oxidized Fenton-like system, triggering the rapid decomposition of persulfate. Ti₂C₃T x The MXene / Fe-MIL-88NH2 cascade catalytic system works simultaneously to rapidly catalyze the decomposition of persulfate and initiate the free radical polymerization of hydrophilic monomers to form a hydrogel.

[0150] Experimental Example 2: The number and types of free radicals generated in different systems

[0151] Using electron paramagnetic resonance (EPR) technology, with 5,5-dimethyl-1-pyrrolline-N-oxide (DMPO) as a free radical scavenger, for persulfate and Ti2C3T xThe number and types of free radicals generated during the MXene and Fe-MIL-88NH2 reactions were characterized.

[0152] Experimental results are as follows Figure 3 As shown.

[0153] The results showed that pure MXene could not generate free radicals, while the addition of persulfate resulted in Ti2C3T x Characteristic peaks of 1:2:2:1 corresponding to ·OH radicals were found in both the MXene and Fe-MIL-88NH2 systems, proving that both systems can generate ·OH radicals. The peak intensity was weaker in the Fe-MIL-88NH2 system, and the intensity difference indicates that MXene / S2O8 2- The system generates relatively more free radicals. And in Ti2C3T... x In the MXene / Fe-MIL-88NH2 cascade catalytic system, due to the high catalytic efficiency, more ·OH radicals and a small amount of ·SO4 were generated in a short time. - This proves Ti2C3T x The improved synergistic catalytic efficiency of MXene and Fe-MI L-88NH2, i.e., Ti2C3T x The high catalytic efficiency of the MXene / Fe-MIL-88NH2 cascade catalytic system.

[0154] Simultaneously, UV-Vis spectrophotometry was used to demonstrate that the cascade catalytic system reacted with persulfate to produce Fe. 2+ Fe 2+ It can react with K3[Fe(CN)6] to produce Prussian blue nanoparticles, which turn the solution blue and have an absorption peak at around 700 nm. Figure 3 Figure b shows that, under the same treatment conditions, the Fe-MIL-88NH2 / SPS system could not change the color of the K3[Fe(CN)6] solution, while the Ti2C3T system... x Fe was generated during the reaction of the MXene / Fe-MI L-88NH2 / SPS system. 2+ This resulted in an absorption peak at around 700 nm, confirming the presence of Ti2C3T in the cascade catalytic system. x MXene promotes the development of Fe-MIL-88NH2 nanozyme Fe 3+ / Fe 2+ The cycle.

[0155] Experimental Example 3: Temperature Changes in Different Prepolymer Systems During the Gel Formation Process and the Influence of Different Systems on the Gel Formation Rate

[0156] First, a schematic diagram of the MXene / Fe-MIL-88NH2 cascade catalytic system initiating rapid gelation was drawn, as shown below. Figure 4 As shown in Figure a

[0157] (1) The temperature changes during the gelation process of Example 1 and Comparative Example 2 were characterized using an infrared imager. The experimental results are as follows: Figure 4 As shown in Figures b and c.

[0158] Under mild conditions, in MXene / S2O8 2- In the system, a certain amount of ·OH free radicals are generated initially, but this is insufficient to initiate the polymerization and crosslinking of acrylic acid. The temperature of the precursor solution only begins to rise after about 200 seconds, reaching a maximum of about 50°C, and the gelation process takes about 600 seconds. (The last sentence appears to be incomplete and possibly refers to a different process.) 2- In the cascade catalytic system, due to the addition of Fe-MIL-88NH2, Fe reacts with MXene to produce Fe 2+ It has strong reducing properties and can react with S2O8. 2- This forms a highly oxidized Fenton-like system, generating Fe. 3+ This, in turn, initiates Fe 3+ / Fe 2+ The cycle significantly improves the catalytic efficiency. After the initiator is added, a large number of free radicals are randomly generated to supply the acrylic monomers to polymerize into a gel, thereby generating a large amount of heat. The maximum temperature reaches about 60°C, and the polymerization and cross-linking process can be completed in about 50 seconds.

[0159] (2) For different Ti2C3T x The gelation time of the hydrogel at the MXene / Fe-MIL-88NH2 ratio was characterized. The experimental results are as follows: Figure 4 As shown in Figure d.

[0160] Changing the Ti2C3T content in the precursor solution x Hydrogels were prepared by adjusting the content of MXene and Fe-MIL-88NH2, and the specific preparation method is described in Example 1. The Ti2C3T precursor solution... x The contents of both MXene and Fe-MIL-88NH2 can affect the gelation rate of hydrogels. As shown in Comparative Examples 1-3 and Examples 9-12, the content of Fe-MIL-88NH2 has a more significant effect on promoting the gelation rate and can significantly shorten the gelation time. The gelation rate of Comparative Examples 1-3 without Fe-MIL-88NH2 is significantly lower than that of the MXene / Fe-MIL-88NH2 cascade catalytic system. By adjusting the content of Fe-MIL-88NH2 in the precursor solution, hydrogels can be prepared in as little as 13 seconds.

[0161] Experimental Example 4: Universality Experiment of MXene / Fe-MIL-88NH2 Cascade Catalytic System

[0162] The MXene / Fe-MIL-88NH2 cascade catalytic system was introduced into the gelation process of various hydrophilic monomers, including acrylic acid (Example 1), acrylamide (Example 2), and N,N-dimethylacrylamide (Example 3), and the gelation time was recorded for each. The MXene / Fe-MIL-88NH2 cascade catalytic system was also introduced into various initiators, including ammonium persulfate (Example 4), potassium persulfate (Example 5), and hydrogen peroxide (Comparative Example 4).

[0163] Experimental results are as follows Figure 5 As shown.

[0164] like Figure 5 Figures a-d show the introduction of an MXene / Fe-MIL-88NH2 cascade catalytic system into solutions of acrylic acid, acrylamide, N,N-dimethylacrylamide, and N-isopropylacrylamide precursors, where Fe-MIL-88NH2 represents 0.015% of the monomer by mass. The final gelation times were 43 s, 73 s, 767 s, and 833 s, respectively. All gelation processes were completed within 15 min, demonstrating that the cascade catalytic system is suitable for preparing hydrogels from various acrylic monomers. Furthermore, the weakly acidic environment (pH approximately 3) in acrylic acid is more conducive to the catalytic process within the hydrogel, resulting in the fastest gelation rate.

[0165] like Figure 5 As shown in Figure e, MXene can construct a cascade catalytic system with Fe3O4 nanoparticles, which are also iron-based metal nanozymes, to rapidly initiate the free radical polymerization of hydrophilic monomers. The mass percentage of Fe3O4 nanoparticles relative to the monomers is 0.01%, and the final gelation time is 141 s. This demonstrates that MXene can construct a cascade catalytic system with various iron-based metal nanozymes to initiate rapid gelation. Furthermore, due to the larger specific surface area and porous structure of Fe-MIL-88NH2 with its octahedral structure, it can catalyze the decomposition of peroxides more efficiently.

[0166] like Figure 5 Figures f-h show that the MXene / Fe-MIL-88NH2 cascade catalytic system can initiate the decomposition of peroxides such as ammonium persulfate, potassium persulfate, and hydrogen peroxide at 51s, 56s, and 862s, respectively, to generate free radicals, thereby initiating monomer free radical polymerization. This demonstrates that the MXene / Fe-MIL-88NH2 cascade catalytic system has high versatility and can be applied to various peroxide initiator systems to promote gelation.

[0167] Based on the above characterization results, the reactions that occur during the catalytic process are shown in Table 1:

[0168] Table 1 Reactions occurring during the catalytic process

[0169]

[0170] Based on the reaction equations in the table above, it can be seen that some Ti 2+ / Ti 3+ With S2O8 2- A redox reaction occurs, producing a small amount of SO4. - However, this process is slow at room temperature. Subsequently, the Fe in the Fe-MIL-88NH2 nanomolecules... 3+ With Ti 2+ / Ti 3+ A reaction occurs, producing Fe. 2+ Fe 2+ It can be further combined with S2O8 2- This forms a highly oxidizing Fenton-like system and generates SO4. - SO4 2- and Fe 3+ This initiated Fe 3+ / Fe 2+ The cyclic process. The addition of MXene not only provides the cyclic system with Ti having reducing properties, but also... 2+ and Ti 3+ Furthermore, due to its excellent electrical properties, it also promotes electron transport within redox systems. This channel allows Fe... 3+ / Fe 2+ The cycle process proceeds efficiently, catalyzing the rapid decomposition of persulfate, and further generating a large number of ·OH free radicals and a small amount of oxygen upon contact with water, ultimately triggering the rapid gelation of the precursor solution.

[0171] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for rapidly initiating free radical polymerization of hydrophilic monomers to prepare hydrogels, characterized in that, Includes the following steps: (1) Mix the hydrophilic monomer with water evenly, add the mixed dispersion of MXene and iron-based metal nanoenzyme material, stir and sonicate to obtain the precursor solution; (2) Add peroxide solution to the precursor solution obtained in step (1), mix well and then prepare the product; In step (1), the iron-based metal nanozyme is a metal-organic framework material Fe-MIL-88NH2; the mass ratio of MXene to iron-based metal nanozyme is 30:1-100:1; the total mass of MXene and iron-based metal nanozyme material is 0.5%-1.0% of the mass of hydrophilic monomers.

2. The method for preparing hydrogels by rapid initiation of hydrophilic monomer free radical polymerization according to claim 1, characterized in that, The hydrophilic monomer in step (1) includes at least one of acrylic acid, acrylamide, N,N-dimethylacrylamide and N-isopropylacrylamide.

3. The method for preparing hydrogels by rapidly initiating free radical polymerization of hydrophilic monomers according to claim 1, characterized in that, In step (1), the mass ratio of hydrophilic monomer to water is 1:3-1:

1.

4. The method for preparing hydrogels by rapidly initiating free radical polymerization of hydrophilic monomers according to claim 1, characterized in that, The total concentration of the mixed dispersion of MXene and iron-based metal nanoenzyme material in step (1) is 5-10 mg / mL.

5. The method for preparing hydrogels by rapid initiation of hydrophilic monomer free radical polymerization according to claim 1 or 4, characterized in that, In step (1), MXene is Ti2C3T x MXene.

6. The method for preparing hydrogels by rapidly initiating free radical polymerization of hydrophilic monomers according to claim 5, characterized in that, Ti2C3T x The mass ratio of MXene to Fe-MIL-88NH2 is 67:

1.

7. The method for preparing hydrogels by rapidly initiating free radical polymerization of hydrophilic monomers according to claim 1, characterized in that, In step (1), the stirring speed is 200-500 rpm and the time is 5-20 min.

8. The method for preparing hydrogels by rapidly initiating free radical polymerization of hydrophilic monomers according to claim 1, characterized in that, In step (1), the ultrasonic power is 50-200 W and the time is 5-20 min.

9. The method for preparing hydrogels by rapid initiation of hydrophilic monomer free radical polymerization according to claim 1, characterized in that, In step (2), the peroxide solution is at least one of sodium persulfate, ammonium persulfate, potassium persulfate and hydrogen peroxide solution, with a concentration of 100-200 mg / mL and a volume ratio of persulfate to precursor solution of 1:5-1:20; the reaction time is 10-900 s.

10. A hydrogel prepared by the method for preparing hydrogels by rapid initiation of hydrophilic monomer free radical polymerization according to any one of claims 1-9.

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