Multi-walled carbon nanotube composite material covalently modified by azide group and comb-type porphyrinyl polymer and preparation method of multi-walled carbon nanotube composite material covalently modified by azide group and comb-type porphyrinyl polymer

Abstract

The invention belongs to the field of nonlinear optical materials, and discloses a multiwalled carbon nanotube composite material covalently modified by azide groups and comb-type porphyrin macromolecules, and the composite material has good nonlinear absorption characteristics and good dispersibility in a solid matrix, and can be used for preparing optical devices. The invention mainly aims to solve the problem that porphyrin and multi-walled carbon nanotubes are poor in aggregation and dispersibility in an organic reagent, comb-type porphyrinyl macromolecules are constructed and are used for covalent modification of the surfaces of the multi-walled carbon nanotubes; the conjugacy of the multiwalled carbon nanotube is further improved by using an azide group with a conjugated structure, and the prepared composite material integrates the nonlinear optical characteristics of porphyrin and the multiwalled carbon nanotube; and meanwhile, by utilizing the synergistic effect of multiple components, the composite material has better nonlinear optical characteristics compared with a single material under the same concentration, and has a good application prospect in the field of practical application.

Description

Technical Field

[0001] The present invention belongs to the field of nonlinear optical materials, and in particular relates to a multi-walled carbon nanotube composite material covalently modified with an azide group and a comb-type porphyrin-based polymer and a preparation method thereof. Technical Background

[0002] Multi-walled carbon nanotubes (MWCNTs), tubular two-dimensional materials derived from rolled graphene, possess a large π-conjugated structure, offering promising applications in a variety of fields, including photovoltaics, photocatalysis, nanoelectronic devices, and hydrogen storage materials. In particular, due to their excellent π-electron conjugation and thermal stability, MWCNTs exhibit excellent nonlinear absorption properties, making them widely used in the development of nonlinear optical materials. However, their poor dispersibility in organic reagents severely limits their potential for practical applications in nonlinear optics. Improving the dispersibility of MWCNTs has become a hot topic of research in this field.

[0003] Porphyrins, with their 18π-electron conjugated structure, are porphyrins, and porphyrins with substituents are known as porphyrins. They possess excellent optoelectronic properties and have significantly advanced fields such as photocatalysis, photodynamics, and new energy. In particular, due to their large π-conjugated structure, porphyrins offer advantages such as high nonlinear absorption coefficients and fast response, making them excellent nonlinear optical materials. Combining porphyrins with multi-walled carbon nanotubes (MWCNTs) not only combines the advantages of both, but also exhibits a significant photoinduced electron / energy transfer effect between the porphyrins and MWCNTs. This results in materials with enhanced nonlinear optical properties, rather than simply the sum of the two. This has sparked a wave of research in the field of nonlinear optics. However, due to the pronounced conjugated structure of porphyrins, π-π interactions lead to a significant tendency for intermolecular aggregation during the incorporation process. This reduces the porphyrin's dispersibility in organic reagents, hinders their binding, and severely inhibits the improvement of the composite's nonlinear optical properties. People usually construct porphyrin-based polymers and use the spatial effect produced by porphyrin-based polymers to inhibit the aggregation of porphyrin molecules. However, there are few reports on the covalent modification of multi-walled carbon nanotubes with porphyrin-based polymers.

[0004] With the advancement of science and technology, existing materials can no longer meet the demand for nonlinear optical materials. In an era where binary composite materials are constantly emerging, ternary composite materials have become a hot topic of discussion. The most effective criterion for determining a material's nonlinear optical properties is its conjugation. Azide groups, due to their double σ bonds, possess a certain degree of conjugation, allowing them to be modified with various substances in a simple and effective manner to prepare new materials. Therefore, by covalently linking porphyrin-based polymer groups and azide groups to multi-walled carbon nanotubes through a covalent bond, the construction of ternary composite materials is expected to yield new nonlinear optical materials with excellent nonlinear optical properties. Summary of the Invention

[0005] The present invention belongs to the field of nonlinear optical materials and discloses a multi-walled carbon nanotube nonlinear absorption optical composite material covalently modified with an azide group and a comb-type porphyrin-based polymer group. The composite material has good nonlinear absorption characteristics and good dispersibility in a solid matrix. It can be used to prepare optical devices and has great application potential in practical applications in the field of nonlinear optics. The structural formula is shown below:

[0006]

[0007] Where: n is the degree of polymerization of the comb-shaped porphyrin polymer, 3≤n≤12

[0008] The molecular weight of the poly 6-(4-formylphenoxy)hexyl methacrylate with porphyrin groups is in the range of 2700-9700.

[0009] The present invention discloses a multi-walled carbon nanotube composite material covalently modified with an azide group and a porphyrin-based polymer group, and a preparation method thereof. The preparation of the porphyrin polymer is a reversible addition-fragmentation chain transfer polymerization method. First, 6-(5-(4-phenoxy)-10,15,20-triphenylporphyrin)-1-hexanol is prepared by an etherification reaction. Then, methacryloyl chloride is used to modify the double bond to form 6-(5-(4-phenoxy)-10,15,20-triphenylporphyrin) methacrylate. Then, a comb-shaped porphyrin-based polymer is synthesized by reversible addition-fragmentation chain transfer polymerization using a chain transfer agent containing an alkyne group. Finally, a click chemistry reaction is carried out with multi-walled carbon nanotubes containing azide groups to prepare a multi-walled carbon nanotube composite material covalently modified with an azide group and a porphyrin-based polymer group.

[0010] The technical effect of the present invention is that a multi-walled carbon nanotube composite material covalently modified by an azide group and a porphyrin-based polymer group has good dispersibility in a solid organic reagent and good nonlinear optical properties, which can be authenticated by Z scanning. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is the infrared transmission spectrum of the nanocomposite material of comb-type porphyrin, azide-modified multi-walled carbon nanotubes and porphyrin polymer-modified multi-walled carbon nanotubes.

[0012] Figure 2 This is the NMR spectrum of PPor5-C≡CH.

[0013] Figure 3 Raman spectra of MWCNT-N3 and N3-MWCNT-PPor5.

[0014] Figure 4 for Figure 4 The concentration of N3-MWCNT-PPor3(A), N3-MWCNT-PPor5(B), N3-MWCNT-PPor9(C), N3-MWCNT-PPor 12 (D).

[0015] Figure 5 This is a photo of an optical resin sheet. DETAILED DESCRIPTION

[0016] The present invention provides a porphyrin polymer-modified multi-walled carbon nanotube nanocomposite material and a preparation method thereof (since the structures of this series of comb-type porphyrin-based polymers are similar, only the molecular weights differ. Therefore, taking the comb-type porphyrin-based polymer PPor5-C=CH as an example, its molecular weight is 4200, and its mass ratio with the multi-walled carbon nanotube containing azide groups is 1:2 as an example), the specific embodiments are as follows:

[0017] 5-(4-Hydroxyphenyl)-10,15,20-triphenylporphyrin (Por-OH) was synthesized using the Adler method. The specific process is 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, the reaction solution was then refluxed. Pyrrole (5 mL, 72 mmol) dissolved in 20 mL of propionic acid was then added dropwise via a constant pressure dropping funnel. After the addition was complete, the mixture was stirred at reflux for 2 hours. After the reaction was completed, 60 mL of ethanol was added at 60°C and stirred for 15 minutes. The mixture was then allowed to stand for 12 hours and filtered under reduced pressure for solid-liquid separation. The filter cake was washed with ethanol until the filtrate was colorless. The filter cake was collected and dried in a vacuum drying oven overnight. The dried solid was separated and purified by column chromatography with dichloromethane as the eluent. The second color band product 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%.

[0018] The reaction formula is:

[0019] 6-(5-(4-phenoxy)-10,15,20-triphenylporphyrin)-1-hexanol was prepared via the Williamson ether synthesis reaction. The specific preparation process is as follows: Acetonitrile (30 mL), potassium hydroxide (18.23 mg, 0.33 mmol), and Por-OH (0.2 g, 0.31 mmol) prepared in Section 3.2.2.1 were added to a two-necked flask in sequence. After stirring for 30 minutes, 6-chloro-1-hexanol (0.5 g, 3.83 mmol) was added to the reaction system and stirred at 90°C for 24 hours. After completion of the reaction, the mixture was cooled to room temperature and dichloromethane (30 mL) was added. The mixed solution was washed with saturated NaHCO3 solution and saturated NaCl solution, respectively. The organic layer was dried over anhydrous Na2SO4, and the filtrate was collected by filtration of the desiccant. The dichloromethane solvent was removed by distillation under reduced pressure. The crude product was purified by column chromatography with dichloromethane as the eluent, and the second band product was collected to obtain 0.21 g of a bright purple solid powder of 6-(5-(4-phenoxy)-10,15,20-triphenylporphyrin)-1-hexanol with a yield of 93% and a chemical formula of Por-O(CH2)6-OH.

[0020] The reaction formula is:

[0021] Por-O(CH2)6-MA was prepared by esterification of hydroxyl groups. Por-O(CH2)6-MA (0.2 g, 0.27 mmol), anhydrous dichloromethane (30 mL) and triethylamine (0.027 g, 0.27 mmol) were added to a 100 mL two-necked flask in sequence. After stirring at 0°C for 30 min, methacryloyl chloride (0.056 g, 0.54 mmol) dissolved in anhydrous dichloromethane (10 mL) was slowly added dropwise to the reaction solution through a constant pressure dropping funnel. mmol and continued stirring at 0°C for 12 hours. After the reaction, the reaction mixture was washed with 0.1 mol / L hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated NaCl solution, respectively, and dried over anhydrous Na2SO4. The desiccant was filtered, and the dichloromethane solvent was removed by vacuum distillation. The resulting crude product was purified by column chromatography using dichloromethane and petroleum ether (v:v, 1:1) as the eluent. The first color band product was collected to obtain 0.172 g of a bright purple solid powder with a yield of 79.8%.

[0022] The reaction formula is:

[0023] PPor5-C≡CH was prepared by the RAFT method. The synthesis method is as follows: Under nitrogen protection, S-1-dodecyl-S'-(a,a'-dimethyl-α"-propynyl acetate) trithiocarbonate (0.024 g, 0.06 mmol), Por-O(CH2)6-MA (0.29 g, 0.36 mmol), AIBN (0.01 g, 0.06 mmol) and anhydrous 1,4-dioxane (1 mL) were added sequentially into a dry two-necked flask and stirred at 75°C for 8 h. After the reaction was completed, the mixture was exposed to air to terminate the reaction. The reaction mixture was poured into n-hexane for sedimentation purification, the insoluble matter was collected by filtration, and dried under vacuum to obtain 0.12 g of PPor5-C≡CH as a deep red solid powder with a yield of 43%.

[0024] The reaction formula is:

[0025] Carboxylated multi-walled carbon nanotubes were prepared using the nitric acid oxidation method, as shown in Figure 4.7 below. The specific preparation process is as follows: Multi-walled carbon nanotubes (MWCNT, 200 mg) and a 3 mol / L aqueous nitric acid solution (30 mL, 0.09 mol) were added sequentially to a 100 mL single-necked flask and stirred at 80°C for 8 hours. After the reaction, the crude product was separated by centrifugation, washed with deionized water, and dried in a vacuum drying oven at 60°C for 24 hours to obtain 167 mg of a black solid powder of carboxylated multi-walled carbon nanotubes with the chemical formula MWCNT-COOH. MWCNT-COOH (100 mg) was added to a 100 mL single-necked flask, followed by thionyl chloride (30 mL). After stirring at 0°C for 24 h, the residual thionyl chloride was removed by vacuum distillation. Anhydrous N,N-dimethylformamide (30 mL) and excess NaN3 (2 g, 30 mmol) were added, and stirring was continued at 0°C for 24 h. After the reaction, the product was poured into 1 L of deionized water, and the crude product was separated by centrifugation. The crude product was washed with a large amount of deionized water and dried in a vacuum drying oven at 60°C overnight to obtain 116 mg of MWCNT-N3 black solid powder.

[0026] N3-MWCNT-PPor5 was prepared using a copper-catalyzed click chemistry reaction between an alkynyl group and an azide group. The experimental route is shown in the figure below. The specific process is as follows: Under a nitrogen atmosphere, cuprous bromide (0.14 mg, 0.001 mmol), N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMEDTA, 2 μL, 0.001 mmol), and DMF (1 mL) were placed on one side of an H-shaped reaction tube and stirred at 25°C for 30 min. DMF (1 mL), PPor5-C≡CH (2.52 mg, 0.6 μmol), and MWCNT-N3 (5 mg) were placed on the other side of the H-shaped reaction tube and stirred thoroughly for 30 min. The mixtures on both sides of the H-shaped reaction tube were mixed at 45°C, stirred for 12 h, and then exposed to air to terminate the reaction. The reaction mixture was poured into deionized water, and the crude product was isolated by centrifugation. The crude product was washed with dichloromethane, ethanol and deionized water and dried under vacuum overnight to obtain N3-MWCNT-PPor5 as a black solid powder.

[0027] The reaction formula is:

[0028] Optical resin sheets were prepared using a casting method. First, a certain amount of azobisisobutyronitrile was dissolved in an appropriate amount of methyl methacrylate. The solution was prepolymerized at 65°C with stirring until a certain viscosity was reached. Next, a DMF suspension containing N3-MWCNT-PPor5 was added to the prepolymer and stirred to disperse uniformly. Finally, the mixture was poured into a mold coated with a release agent and placed in an oven. The mold was heated at 70°C for 3 hours, 80°C for 2 hours, and 90°C for 1 hour. After heating, the device was allowed to cool naturally to room temperature. After demolding, a 2 mm thick solid-state optical device containing the nonlinear optical sample was obtained.

[0029] Figure 1 The infrared transmission spectrum of the nanocomposite material of comb-type porphyrin, azide multi-walled carbon nanotubes and porphyrin polymer modified multi-walled carbon nanotubes in the present invention is shown in Figure 2. The FT-IR spectrum of N3-MWCNT-PPor5 shows that compared with PPor5-C≡CH and MWCNT-N3, PPor5-C≡CH has a higher peak at 2125 cm -1 The stretching vibration peak of C≡C at 2144 cm-1 and the peak of MWCNT-N3 at 2144 cm-1 -1 The asymmetric stretching vibration peak of the azide group is significantly weakened, and the peak at 3150 cm -1 and 1730cm -1 The characteristic peak of triazole ring appears at 2850cm -1 and 2922cm -1 The stretching vibration peak of continuous methylene groups on the main chain of porphyrin polymer is 800 cm -1The characteristic peak at is attributed to the skeleton vibration of porphyrin

[72] . These results preliminarily indicate that PPor5-C≡CH is successfully covalently linked to MWCNT-N3 via a “click” chemical reaction. This demonstrates the successful preparation of a multi-walled carbon nanotube composite material modified with porphyrin polymer and azide groups.

[0030] Figure 2 This is the NMR spectrum of PPor5-C≡CH. δ = 8.75 ppm corresponds to the hydrogen proton peak on the pyrrole ring; δ = 7.20-8.16 ppm corresponds to the hydrogen proton peak on the benzene ring of the porphyrin; δ = 4.20 ppm corresponds to the hydrogen proton peaks on carbons 1 and 6 of the hexyloxy chain attached to the porphyrin; δ = 2.55 ppm corresponds to the hydrogen proton peak in the alkynyl group; and δ = -2.74 ppm corresponds to the chemical shift of the hydrogen proton peak in the -NH- group on the pyrrole ring. Based on the integrated area calculations of the proton peaks for the alkynyl group on the chain transfer agent (δ = 2.55 ppm) and the -NH- group on the pyrrole ring (δ = -2.74 ppm), it is determined that the number of units in a single PPor5-C=CH molecule is 5.

[0031] Figure 3 Figure 2 is the Raman spectra of MWCNT-N3 and N3-MWCNT-PPor5. Compared with MWCNT-N3, the D band and G band of N3-MWCNT-PPor5 shift to lower wavenumbers, which is attributed to the combination of MWCNT and electron donor components. The degree of modification of the MWCNT surface structure is measured by the intensity ratio of the D band to the G band (I D / I G ) is estimated. As shown in Table 1, the I D / I G The ratio is 0.87, while that of N3-MWCNT-PPor5 is reduced to 0.81, indicating that the porphyrin-based polymer group (PPor n ) resulted in a change in the degree of defects on the surface of MWCNT-N3, which once again proved the successful preparation of N3-MWCNT-PPor5.

[0032] Figure 4 For N3-MWCNT-PPor3, N3-MWCNT-PPor5, N3-MWCNT-PPor9, N3-MWCNT-PPor with a concentration of 0.05 g / L 12 In addition, N3-MWCNT-PPor3—N3-MWCNT-PPor 12 Im[χ (3)] value first increases and then decreases with the increase of the molecular weight of PPorx-C≡CH, which may be related to the steric hindrance of PPorx-C≡CH. As the degree of polymerization of PPorx-C≡CH increases, the content of porphyrin in PPorx-C≡CH increases. When combined with a fixed amount of MWCNT-N3, the increase in the porphyrin content in the nanohybrid leads to an upward trend in nonlinear optical (NLO) performance. When the degree of polymerization of PPorx-C≡CH further increases, due to the increase in steric hindrance, the amount of PPorx-C≡CH combined with MWCNT-N3 decreases, resulting in a decrease in the amount of PPorx-C≡CH combined with N3-MWCNT-PPor3—N3-MWCNT-PPor 12 In comparison, the content of porphyrin in the nanohybrid was reduced.

[0033] Figure 5 An optical resin sheet composed of N3-GO-PPor5, PPor5-C≡CH, and MWCNT-N3 was prepared using a casting method with a polymethacrylate matrix at a concentration of 0.05 g / L. The resulting sheet exhibits uniform color distribution and transparency, demonstrating that covalently bonding porphyrin to GO effectively improves the dispersibility of GO and porphyrin in organic media, demonstrating good compatibility and processability.

Claims

1. A composite material of multi-walled carbon nanotubes covalently modified with an azide group and a comb-type porphyrin-based polymer, characterized in that The complex is a ternary complex formed by a comb-shaped porphyrin-based polymer group with porphyrin as a monomer, an azide group and a multi-walled carbon nanotube group through covalent bonds. Its chemical formula is N3-MWCNT-PPor n The structural formula of the multi-walled carbon nanotube complex covalently modified with an azide group and a porphyrin-based polymer group is as follows:

2. The multi-walled carbon nanotube composite material covalently modified with an azide group and a comb-type porphyrin-based polymer according to claim 1, characterized in that The preparation method of the composite is carried out according to the following steps (taking N3-MWCNT-PPor5 as an example): Step 1: Carboxylated multi-walled carbon nanotubes were prepared using a nitric acid oxidation method. The specific preparation process is as follows: Multi-walled carbon nanotubes and a nitric acid aqueous solution of a specific concentration were sequentially added to a 100 mL single-necked flask and stirred at 80°C. After the reaction, the crude product was separated by centrifugation, washed with deionized water, and dried in a vacuum drying oven at 60°C for 24 hours to obtain a black solid powder of carboxylated multi-walled carbon nanotubes with the chemical formula MWCNT-COOH. Step 2: Add MWCNT-COOH to a 100mL single-necked flask, then add thionyl chloride. After stirring at 0°C for 24 hours, remove the residual thionyl chloride by vacuum distillation, add anhydrous N,N-dimethylformamide and excess NaN3, and continue stirring at 0°C for 24 hours. After the reaction is completed, pour the product into 1L of deionized water, separate the crude product by centrifugation, and wash the crude product with a large amount of deionized water. The resulting product is placed in a vacuum drying oven at 60°C and dried overnight to obtain a black solid powder of azidized multi-walled carbon nanotubes with the chemical formula of MWCNT-N3; Step 3: Using S-1-dodecyl-S'-(a,α'-dimethyl-α"-propynyl acetate) trithiocarbonate as a chain transfer agent and azobisisobutyronitrile as an initiator, 6-(5-(4-phenoxy)-10,15,20-triphenylporphyrin)hexyl methacrylate is polymerized to obtain a comb-shaped porphyrin-based polymer with porphyrin as a monomer having a comb-shaped structure, the chemical formula of which is PPor5-C≡CH; Step 4: The MWCNT-N3 obtained in step 2 and the PPor5-C≡CH obtained in step 3 are subjected to a copper-catalyzed click chemistry reaction between the alkynyl group and the azide group to obtain a multi-walled carbon nanotube composite material covalently modified with an azide group and a comb-shaped porphyrin-based polymer, whose chemical formula is N3-MWCNT-PPor5.

3. The method for preparing a composite material of multi-walled carbon nanotubes covalently modified with an azide group and a comb-type porphyrin-based polymer according to claim 2, characterized in that In step 2, the mass ratio of MWCNT-COOH to NaN3 is 1:10 to 1:

20.

4. The method for preparing a composite material of multi-walled carbon nanotubes covalently modified with an azide group and a comb-type porphyrin-based polymer according to claim 2, characterized in that In step 1, the concentration of nitric acid is 2 mol / L to 3 mol / L.

5. The method for preparing a composite material of multi-walled carbon nanotubes covalently modified with an azide group and a comb-type porphyrin-based polymer according to claim 2, characterized in that In step 4, the mass ratios of PPor5-C=CH and MWCNT--N3 are 3:1, 3:3, 3:5 and 3:

7.

6. The method for preparing a composite material of multi-walled carbon nanotubes covalently modified with an azide group and a comb-type porphyrin-based polymer according to claim 2, characterized in that In step 1, the stirring time of the multi-walled carbon nanotubes and concentrated nitric acid is 8 to 12 hours.

7. The method for preparing a composite material of multi-walled carbon nanotubes covalently modified with an azide group and a comb-type porphyrin-based polymer according to claim 2, characterized in that In step 2, the volume of thionyl chloride added is 30mL-50mL.

8. The multi-walled carbon nanotube composite material covalently modified with an azide group and a comb-shaped porphyrin-based polymer according to claim 1, characterized in that The composite has good dispersibility in a solid organic reagent (such as polymethyl methacrylate) and can be used to prepare an optical resin sheet.

9. The multi-walled carbon nanotube composite material covalently modified with an azide group and a comb-type porphyrin-based polymer according to claim 1 has obvious nonlinear absorption characteristics and can be used as an anti-saturation absorption material.

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