Graphene oxide composite material covalently modified by polymethyl methacrylate polymer with end group containing manganese porphyrin group and preparation method of graphene oxide composite material

Abstract

The invention discloses a graphene oxide composite material covalently modified by a polymethyl methacrylate polymer containing a manganese porphyrin group at an end group and a preparation method of the graphene oxide composite material, and belongs to the technical field of nonlinear optical materials. The composite material is characterized in that the composite material is formed by covalently modifying graphene oxide with polymethyl methacrylate of which the end group contains a manganese porphyrin group. The preparation method of the material comprises the following steps: firstly, preparing the polymethyl methacrylate of which the end group contains the manganese porphyrin group through an atom transfer radical polymerization method; the polymethyl methacrylate covalently modified graphene oxide composite material with the end group containing the manganese porphyrin group is prepared by covalently connecting the polymethyl methacrylate with the graphene oxide, and the material is a nonlinear optical material. The method can be used for preparing the composite material with good nonlinear optical performance.

Description

Technical Field

[0001] A graphene oxide composite material covalently modified with a polymethyl methacrylate polymer containing manganese porphyrin groups at the end groups and its preparation method belong to the field of nonlinear optical materials technology. Background Technology

[0002] Porphyrins are a class of organic compounds with macrocyclic conjugated structures, generally defined as substances with substituents attached to the porphyrin ring. Because their periphery can be replaced by various substituents, the central metal particle can be altered, and even the ring size can be expanded, they possess excellent molecular modifiability. Furthermore, their 18π electron conjugated structure has led to their widespread application in nonlinear optics research. The nonlinear optical principle of porphyrins can typically be explained using a five-level model: when a porphyrin in its ground state (S0) is irradiated with light of a specific wavelength, its internal electrons undergo an electronic transition to the first excited state (S1). At this point, the electrons have three possible paths: first, by further absorbing energy to reach the second excited state (S2); second, the electron in S1 further absorbs energy and undergoes intersystem crossing to reach the triplet state (τ1), subsequently reaching the triplet excited state (τ2) after irradiation with strong light (generally referring to laser light), which is the basic principle of anti-saturation absorption; and third, by releasing energy, the electron in S1 returns to S0. Therefore, how to enable more porphyrins to reach the S1 state is one of the key issues for researchers to study on how to enhance the nonlinear optical properties of porphyrin molecules, that is, to reduce the band gap between S0 and S1.

[0003] In past studies, numerous methods have modified porphyrins with peripheral substituents and central metals, resulting in a redshift of the characteristic absorption peaks. While some progress has been made, metallization increases planarity and rigidity, leading to a significant tendency for porphyrin molecules to aggregate (e.g., J-aggregation). This reduces porphyrin solubility and severely limits its potential for practical applications. Furthermore, current research largely focuses on studying the nonlinear optical properties of porphyrins in liquid systems, which offers limited guidance for practical applications. Directly doping porphyrins into solid-state systems results in inhomogeneous performance due to their poor solubility, significantly hindering the practical application potential of porphyrin-based nonlinear optical materials.

[0004] Graphene oxide, with its sp2 hybrid honeycomb layered morphology and excellent π-electron conjugation structure, has been widely adopted in the field of nonlinear optics. Furthermore, its surface contains numerous oxygen-containing functional groups, which can be covalently grafted onto porphyrins, suppressing the aggregation tendency between porphyrin molecules. Based on this, porphyrins and graphene oxide can also form an electron donor-acceptor system, achieving electron transfer through the conjugated structure of graphene oxide, increasing the relaxation time of electrons within the porphyrin, and improving the S1 absorption cross section, thus enabling the composite material to exhibit superior nonlinear optical properties. Therefore, metallizing porphyrins and covalently linking them with graphene oxide, then chemically bonding the composite material into a solid matrix, holds promise for solving the aforementioned problems. Currently, there are no reports on the combination of metalloporphyrins, polymers, and graphene oxide. Summary of the Invention

[0005] This invention relates to a graphene oxide composite material covalently modified with a polymethyl methacrylate polymer containing manganese porphyrin groups at the ends, and its preparation method. The prepared composite material exhibits excellent nonlinear optical properties and good dispersibility in solid organic reagents, and can be used to prepare optical plastics, showing promising application prospects in the field of nonlinear optics. Its structural formula is shown below:

[0006] The molecular weight of the polymethyl methacrylate polymer with manganese porphyrin end groups is in the range of 5000-10000.

[0007] This invention relates to a graphene oxide composite material covalently modified with a polymethyl methacrylate polymer containing manganese porphyrin groups at its end groups, and its preparation method, belonging to the field of nonlinear optical materials technology. The composite material is characterized by being formed by covalently modifying graphene oxide with polymethyl methacrylate containing manganese porphyrin groups at its end groups. The polymer portion of this material is a polymethyl methacrylate polymer with manganese porphyrin as the end group. The preparation method involves first preparing 5-(4-hydroxyphenyl)-10,15,20-triphenylporphyrin with an asymmetric structure using the Alder method, then preparing 5-(4-hydroxyphenyl)-10,15,20-triphenylmanganese porphyrin via the acetate method, and subsequently preparing 5-(4-2-bromoisobutyrate methoxyphenyl)-10,15,20-triphenylmanganese porphyrin via acylation of hydroxyl groups. 20-Triphenylmanganese porphyrin was used to prepare polymethyl methacrylate (PMMA) with manganese porphyrin end groups via atom transfer radical polymerization. This PMMA was then covalently linked to graphene oxide to prepare a graphene oxide composite material covalently modified with manganese porphyrin end groups. This material is a nonlinear optical material. This method can prepare composite materials with good nonlinear optical properties, and the nonlinear optical properties of the composite material can be modulated by changing the polymer composition of the porphyrin polymer.

[0008] The technical advantage of this invention lies in the fact that a graphene oxide composite material covalently modified from a polymethyl methacrylate polymer with manganese porphyrin end groups exhibits good dispersibility in solid polymethyl methacrylate and good anti-saturation absorption characteristics, which can be verified by open-pore Z-scan testing. Attached Figure Description

[0009] Figure 1 The UV-Vis absorption spectra of MnPor-OH and Por-OH are shown.

[0010] Figure 2 MnPor-Br, PMMA 50 MnPor-PMMA 50 The FT-IR spectrum.

[0011] Figure 3 MnPor-PMMA 50 MnPor-PMMA 83 and MnPor-PMMA 102 The SEC curve.

[0012] Figure 4 MnPor-PMMA 50 Raman spectra of -GO and GO.

[0013] Figure 5 MnPor-PMMA50 GO, MnPor-PMMA 50 -GO Z-scan spectrum.

[0014] Figure 6 Photograph of optical plastic (A) MnPor-PMMA 50 -GO / PMMA (0.05 g / L); (B) MnPor-PMMA 83 -GO / PMMA (0.05 g / L); (C) MnPor-PMMA 102 -GO / PMMA (0.05 g / L). Detailed Implementation

[0015] A graphene oxide composite material covalently modified with a polymethyl methacrylate polymer containing manganese porphyrin groups at its ends, and its preparation method thereof (since this series of polymethyl methacrylate polymers with manganese porphyrin groups at their ends have similar structures, differing only in molecular weight, a polymethyl methacrylate polymer with manganese porphyrin groups at its ends (MnPor-PMMA) with a degree of polymerization of 50 is used). 50 Taking (for example) as an example, the specific implementation method is as follows:

[0016] Por-OH was synthesized using the Adler method. The reaction was as follows: p-hydroxybenzaldehyde (2.20 g, 18 mmol) and benzaldehyde (4.75 mL, 54 mmol) were added sequentially to a 100 mL two-necked flask containing 30 mL of propionic acid. After dissolution and mixing, pyrrole (5 mL, 72 mmol) dissolved in 20 mL of propionic acid was added dropwise to the reaction solution under constant pressure through a dropping funnel. After the addition was complete, the mixture was stirred under reflux for 2 h. After the reaction was completed, 60 mL of ethanol was added at 60 °C, and the mixture was stirred for 15 min. The mixture was then allowed to stand for 12 h, and solid-liquid separation was performed by vacuum filtration. The filter cake was washed with ethanol until the filtrate was colorless. The filter cake was collected and dried overnight in a vacuum drying oven. The dried solid was purified by column chromatography, with dichloromethane as the eluent. The product with the second colored band was collected, and the solvent was removed by vacuum distillation to obtain 0.730 g of bright purple solid powder, with a yield of 7%. FT-IR (KBr pellet) ν: 3510, 3317, 3024, 1596, 1514, 1473, 966, 800 cm -1 ; 1H NMR (500 MHz, CDCl3), δ ppm: 8.87 (m, 8H), 8.24 (m, 6H), 8.12 (m, 2H), 7.62 (m, 9H), 7.20 (m, 2H), 5.19 (s, 1H), -2.74 (s, 2H).

[0017] The reaction formula is:

[0018] MnPor-OH was synthesized using the acetate method, as shown in the following reaction formula: Por-OH (0.5 g, 0.675 mmol) and manganese acetate tetrahydrate (0.49 g, 2 mmol) were added sequentially to a 20 mL container. N,N In a 100 mL two-necked flask, dimethylformamide was thoroughly mixed and stirred at 135°C for 2 h. After the reaction was complete, the mixture was allowed to return to room temperature and poured into a beaker containing 1 L of deionized water. The mixture was stirred for 5 min, and ammonia was added to adjust the pH to neutral. The mixture was then allowed to stand for 12 h. Solid-liquid separation was performed by vacuum filtration. The filter cake was washed with deionized water until the filtrate was colorless. The filter cake was collected and dried overnight in a vacuum drying oven. The dried solid was purified by column chromatography, using dichloromethane as the eluent. The product in the second color band was collected, and the eluent was removed by vacuum distillation to obtain 0.57 g of green solid powder, with a yield of 7%. FT-IR (KBr pellet) ν: 3510, 3027, 1593, 1512, 1477, 968, 798 cm⁻¹ -1 ; 1 H NMR (500 MHz, CDCl3), δ ppm: 8.82 (m, 8H), 8.22 (m, 6H), 8.14 (m, 2H), 7.65 (m, 9H), 7.23 (m, 2H), 5.17 (s, 1H).

[0019] The reaction formula is:

[0020] 5-(4-2-bromoisobutyric acid methoxyphenyl)-10,15,20-triphenylmanganese porphyrin, with the chemical formula MnPor-Br, was prepared by esterification of hydroxyl groups. The reaction formula is as follows: MnPor-OH (0.184 g, 0.27 mmol), 30 mL of anhydrous dichloromethane, and triethylamine (0.027 g, 0.27 mmol) were added to a 100 mL two-necked flask. After stirring at 0 ºC for 30 min, the mixture was added to the solution through a constant pressure dropping funnel using a solution dissolved in 10 mL of anhydrous dichloromethane. α- Bromoisobutyryl bromide (0.028 g, 0.27 mmol) was reacted and the reaction was continued at 0 ºC for 12 h. After the reaction was completed, the mixed solution was subjected to 0.1 mol / L... -1 The sample was washed with dilute hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated NaCl solution, dried with anhydrous Na₂SO₄, filtered to remove the drying agent, and the dichloromethane solvent was removed by vacuum distillation. The crude product was purified by column chromatography, with dichloromethane and petroleum ether (V:V, 1:1) as the eluent. The first band of product was collected to give 0.158 g of bright purple solid powder, with a yield of 75%. FT-IR (KBr pellet) ν: 3024, 1748, 1603, 1518, 1474, 1293, 963, 800 cm⁻¹ -1 ; 1 H NMR (500MHz, CDCl3): δ ppm: 8.80 (m, 8H), 8.25 (m, 8H), 7.78 (m, 9H), 7.56 (d, 2H), 2.21 (m, 6H).

[0021] The reaction formula is:

[0022] MnPor-PMMA was prepared by the ATRP method. 50 The reaction is as follows: under nitrogen protection, cuprous bromide (1.4 mg, 0.01 mmol) is reacted. N,N,N′,N′′,N′′ -Pentamethyldivinyltriamine (PMEDTA, 20 μL, 0.01 mmol) and DMF (1 mL) were placed on one side of an H-type reaction tube and stirred at room temperature for 30 min. DMF (1 mL), MnPor-Br (6.84 mg, 0.01 mmol), and MMA (106 μL, 1 mmol) were placed on the other side of the H-type reaction tube and stirred thoroughly for 30 min. The mixture from both sides of the H-type reaction tube was mixed at 45 ºC, and the reaction was terminated by exposing the mixture to air after 12 h. The resulting solution was diluted with THF, purified by neutral alumina precipitation to remove residual copper complexes, and purified by precipitation in cold methanol. The insoluble matter was collected by filtration and dried under vacuum to obtain 37.5 mg of dark red solid powder, with a yield of 39.4%. M n, GPC 0.5×10 4 g mol -1 ; M n , MALS 0.52×10 4 g mol -1 ; Mw / M n (GPC) = 1.04.

[0023] The reaction formula is:

[0024] MnPor-PMMA was prepared by the Williamson ether synthesis reaction. 50 -GO, the reaction formula is as follows, and the specific preparation process is as follows: First, acetonitrile (10 mL, 0.19 mmol) is added to a two-necked flask, and excess anhydrous potassium carbonate is added. After stirring at room temperature for 30 min, GO (5 mg) is added to the above solution, and stirring is continued for another 30 min. Finally, MnPor-PMMA is added to the reaction system. 50 (3 mg, 0.6 μmol) was stirred at 90 ºC for 24 h, and the crude product was separated by centrifugation. The crude product was washed with dichloromethane, ethanol and deionized water to obtain MnPor-PMMA. 50 -GO black solid powder.

[0025] The reaction formula is:

[0026] Optical resin sheets containing Por-PMMA-g-C3N4 were prepared by casting. First, a certain amount of azobisisobutyronitrile (AIBN) was dissolved in an appropriate amount of methyl methacrylate (MDMA). The solution was prepolymerized to a certain viscosity by stirring at 65 °C. Next, a DMF solution containing a nonlinear optical sample was added to the prepolymer and stirred to disperse it evenly. Finally, the mixture was poured into a mold coated with a release agent and placed in an oven. The oven was heated at 70 °C for 3 h, 80 °C for 2 h, and 90 °C for 1 h. After heating, the mixture was allowed to cool naturally to room temperature. After demolding, a 2 mm thick solid optical plastic resin sheet containing the nonlinear optical sample was obtained.

[0027] The UV-vis spectra of MnPor-OH and Por-OH in DMF are as follows: Figure 1 As shown in the figure, a strong absorption peak of Por-OH at 413 nm can be observed, belonging to the B band of porphyrin, and four weak absorption characteristic peaks between 500-700 nm, belonging to the Q band of porphyrin. After Por-OH coordinates with Mn(CH3COO)2, its Q band changes from four to two due to orbital degeneracy, leading to increased molecular symmetry, and is located at 612 nm and 651 nm respectively. The absorption peak at 473 nm belongs to the B band of porphyrin. Compared with Por-OH, its B band exhibits a 60 nm redshift, which can be expressed by formula E.g =1240 / λ g The calculated band gap decrease is approximately 0.38 eV.

[0028] MnPor-PMMA 50 The FT-IR spectrum is as follows Figure 2 As shown, compared to MnPor-Br, most of the characteristic peaks are retained, with MnPor-Br located at 650 cm⁻¹. -1 The characteristic peaks at 2922 and 2850 cm⁻¹ disappear, and the peaks at 2922 and 2850 cm⁻¹ also disappear. -1 A new characteristic vibrational peak appears, attributed to the stretching vibration of the continuous methylene groups in the PMMA backbone, at 1750 cm⁻¹. -1 The characteristic peak at 1242 cm⁻¹ is attributed to the C=O stretching vibration peak of the ester group in PMMA. -1 The characteristic peaks at 986 and 800 cm⁻¹ are attributed to the CO stretching vibration peaks in the ester group of PMMA. -1 The characteristic vibrational peaks at that location are attributed to the characteristic vibrational peaks of the porphyrin ring skeleton.

[0029] Figure 2 MnPor-PMMA 50 of 1 The ¹H NMR spectra show that δ=8.23 ppm corresponds to the chemical shift of the proton peak on the benzene ring in porphyrin; δ=8.87 ppm corresponds to the chemical shift of the proton peak on the pyrrole ring; δ=3.51 ppm corresponds to the chemical shift of the proton peak on the methoxy group in MMA; and δ=1.79 ppm corresponds to the chemical shift of the proton peak in the continuous methylene group on the main chain of MMA. Based on the integrated areas of the proton peaks on the methoxy group and the pyrrole ring in MMA, the chemical shifts of the three polymers MnPor-PMMA are calculated. n The number of units in the molecular chain is 50, 83 and 102, respectively.

[0030] Figure 3 Three polymers, MnPor-PMMA n The SEC curves of the three polymers, Por-PMMA, showed a narrow, single-peak distribution. As the degree of polymerization increased and the elution time decreased, the SEC curve shifted to the left, indicating that the molecular weight of the polymer could be controlled by adjusting the ratio of monomer to initiator. Throughout the polymerization process, the molecular weight distribution of the polymers was relatively uniform, all less than 1.1, demonstrating good controllability. The number-average molecular weights (NMRs) of the three polymers were determined by GPC and SLS. M n ), weight-average molecular weight ( M w The molecular weight distribution and molecular weight distribution showed good consistency with theoretical values, demonstrating the controllable activity of ATRP polymerization. Meanwhile,M n，MALS and M n，GPC The consistency demonstrated further indicates that the porphyrin group is bonded to the end of the polymer chain, and the steric effect of the polymer chain effectively inhibits the aggregation between porphyrin molecules. This effectively improves the nonlinear optical properties of porphyrin. Based on the above data, it is proven that MnPor-PMMA... n It was successfully synthesized.

[0031] Figure 4 For GO and MnPor-PMMA 50 The Raman spectra of MnPor-PMMA and its related structures are listed in Table 1. Table 1 shows that, compared to GO, MnPor-PMMA... 50 - The characteristic peaks of GO in GO shift to lower wavenumbers due to the binding of GO with electron donor components. The degree of modification of the GO surface structure is measured by the intensity ratio of the D band to the G band ( I D / I G To estimate, generally speaking, as the degree of surface modification increases, I D / I G The values ​​of GO and MnPor-PMMA increase, as shown in Table 1. 50 The covalent bonding of GO and MnPor-PMMA perfectly illustrates this point. 50 After covalent bonding, its I D / I G The value increased from 0.97 to 1.08.

[0032] Table 1 GO and MnPor-PMMA 50 -GO Raman spectral data

[0033] Figure 5 MnPor-PMMA 50 Z-scan curve of GO in DMF solvent, compared with GO and MnPor-PMMA 50 Compared to the significant "V"-shaped transmittance, this indicates that MnPor-PMMA exhibits a higher transmittance. 50 -GO exhibits strong nonlinear absorption properties. MnPor-PMMA 50 -GO's β The value is 3.7 × 10 -9 m / W, significantly higher than MnPor-PMMA 50The improvement in nonlinear optical performance, along with GO, is attributed to the cumulative effect of the following three factors: firstly, the use of Mn 2+ Modification of porphyrins effectively reduces the electronic band gap in porphyrin molecules, thereby increasing the excited-state absorption cross section and thus enhancing the nonlinear optical properties of the material; secondly, it involves the cumulative effect of the inherent nonlinear optical properties of porphyrins and GO themselves. It is worth noting that GO... β and Im [χ (3) The negative value may be due to the following reasons: For GO, due to its graphene-like structure, according to the Pauli exclusion principle, the interband light absorption of GO is easily saturated under strong excitation, resulting in an upward absorption peak; thirdly, there is photoinduced electron or energy transfer between porphyrin and GO groups. This transfer effect can generate charge separation excited states, thereby producing large nonlinear absorption and further improving nonlinear optical performance.

[0034] Figure 6 This refers to a 0.05 g / L MnPor-PMMA concentrate prepared using polymethyl methacrylate as a matrix via a casting molding method. 50 -GO, MnPor-PMMA 83 -GO, MnPor-PMMA 102 -GO optical resin sheet. It can be seen that the prepared optical resin sheet has a uniform color distribution and is transparent, indicating that porphyrin is fixed on the surface of graphite oxide by covalent bonds and the composite material is covalently linked with polymethyl methacrylate. On the one hand, it can inhibit the aggregation between porphyrin molecules, and on the other hand, it can increase the dispersion of the composite material in the solid mechanism, so that it has good compatibility and processability.

Claims

1. A graphene oxide composite material covalently modified from a polymethyl methacrylate polymer with manganese porphyrin end groups, characterized in that... This composite material is formed by covalent bonds between polymethyl methacrylate groups with manganese porphyrin as the end group and graphene oxide, and its chemical formula is MnPor-PMMA. n -GO, the structural formula of the graphene oxide composite material covalently modified by polymethyl methacrylate polymer with manganese porphyrin groups at the end is as follows: 。 2. The graphene oxide composite material covalently modified from a polymethyl methacrylate polymer with manganese porphyrin end groups according to claim 1, characterized in that... The preparation method of this composite material is carried out according to the following steps: Step 1: First, add monohydroxyporphyrin and Mn(CH3COO)2·4H2O to a three-necked flask, and add DMF to dissolve the reactants. Place the flask in a constant temperature water bath and stir overnight under reflux. Then, pour the reactants into distilled water to settle, and let stand overnight. Centrifuge at 10000 r / min for 5 min using a benchtop high-speed centrifuge. Collect the precipitate and dry it for 24 h to obtain a blue-purple solid powder with the chemical formula MnPor-OH. Step 2: Add MnPor-OH, anhydrous dichloromethane, and triethylamine to a two-necked flask, stir at room temperature, and add the solution dissolved in anhydrous dichloromethane through a constant-pressure dropping funnel. α - Bromoisobutyryl bromide, and the reaction was continued in an ice-water bath. After the reaction was completed, the mixed solution was subjected to 0.1 mol L... -1 The product was washed with dilute hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated NaCl solution, dried with anhydrous Na2SO4, filtered to remove the drying agent, and the dichloromethane solvent was removed by vacuum distillation. The crude product was purified by column chromatography, with dichloromethane and petroleum ether as the eluent. The first color band product was collected to obtain a blue-purple solid powder with the chemical formula MnPor-Br. Step 3: Polymethyl methacrylate polymers with manganese porphyrin end groups were prepared by the ATRP method. The specific method is as follows: under nitrogen protection, cuprous bromide, ... N,N,N′,N′′,N′′ -Pentamethyldivinyltriamine and N, N - Dimethylformamide was placed on one side of an H-type reaction tube and stirred at room temperature. N, N Dimethylformamide, Mn-Por-Br, and methyl methacrylate were placed on the other side of an H-type reaction tube and stirred thoroughly. The mixtures from both sides of the H-type reaction tube were then combined. After the reaction was complete, the mixture was exposed to air to terminate the reaction. The resulting solution was diluted with THF, purified by neutral alumina to remove residual copper complexes, and then purified by precipitation in cold methanol. The insoluble matter was collected by filtration and dried under vacuum to obtain a pale purple solid powder of a polymethyl methacrylate polymer with porphyrin end groups, its chemical formula being MnPor-PMMA. n ; Step 4: Prepare MnPor-PMMA using the Williamson ether synthesis reaction. n -GO, the specific preparation process is as follows: First, acetonitrile is added to a two-necked flask, anhydrous potassium carbonate is added, and the mixture is stirred at room temperature. Then, graphene oxide is added to the above solution, and stirring continues. Finally, Por-PMMA is added to the reaction system. n The mixture was stirred at 80ºC for 24 h, and the crude product was separated by centrifugation. The crude product was washed with dichloromethane, ethanol, and deionized water to obtain a brown solid powder of graphene oxide composite material covalently modified with polymethyl methacrylate polymer containing porphyrin groups at the end groups. Its chemical formula is Por-PMMA. n -GO.

3. The graphene oxide composite material covalently modified from a polymethyl methacrylate polymer with manganese porphyrin end groups according to claim 1, characterized in that, In the formula, n is the degree of polymerization of PMMA, which ranges from 105 to 200.

4. The method for preparing a graphene oxide composite material covalently modified from a polymethyl methacrylate polymer with manganese porphyrin end groups according to claim 2, wherein in step one, the molar ratio of monohydroxyporphyrin to Mn(CH3COO)2·4H2O is 1:2.

5.

5. The method for preparing a graphene oxide composite material covalently modified from a polymethyl methacrylate polymer with manganese porphyrin end groups according to claim 2, wherein in step two, the mobile phase purified by column chromatography is a mixture of dichloromethane and petroleum ether in a volume ratio of 1:

10.

6. The method for preparing a graphene oxide composite material covalently modified from a polymethyl methacrylate polymer with manganese porphyrin end groups according to claim 2, wherein in step three, cuprous bromide, N,N,N′,N′′,N′′ The molar ratio of 1:1:1 is pentamethyldivinyltriamine and Mn-Por-Br.

7. In the preparation method of graphene oxide composite material covalently modified by polymethyl methacrylate polymer with manganese porphyrin group at the end group according to claim 2, in step four, anhydrous potassium carbonate should be added in excess until the acetonitrile solution changes from colorless to clear.

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