Method for measuring molecular weight of polycarbazole

Abstract

The invention discloses a polycarbazole molecular weight determination method, and relates to the technical field of polymers. The method comprises the following steps: preparing a standard solution and a to-be-detected solution, establishing a standard correction curve by using the standard solution, and calculating the relative molecular weight of the to-be-detected solution by using the standard correction curve. According to the method, the linear relation (namely a standard correction curve) between the molecular weight logarithm and the retention time is established through a polystyrene standard solution (known molecular weight), accurate quantification is achieved through a marker with the known molecular weight, and errors caused by assumption of a polymer structure are avoided; the molecular weight distribution characteristics of the polymer can be directly judged through the peak appearance time, width and area in the chromatogram, and the data is visual and convenient to analyze and compare; and the blank of the polycarbazole molecular weight determination method is filled.

Description

Technical Field

[0001] This invention relates to the field of polymer technology, specifically to a method for determining the molecular weight of polycarbazole. Background Technology

[0002] Polycarbazole conjugated polymers are a class of organic polymers with a unique structure containing carbazole groups in their main chain. This enhances the polymer's stability, allowing it to maintain stable performance under harsh environments such as high temperatures and strong light, thus endowing these polymers with excellent physical and chemical properties. Due to their superior photoelectric properties, polycarbazole conjugated polymers are widely used in the fabrication of optoelectronic devices such as solar cells and organic light-emitting diodes (OLEDs). They also show great potential in energy storage and conversion. For example, they can be used as electrode materials in supercapacitors, providing high energy density and rapid charge / discharge capabilities; furthermore, they can be applied in fuel cells to improve fuel utilization and battery output power.

[0003] Molecular weight is one of the important performance indicators of polycarbazole, which directly affects its physical and chemical properties such as heat resistance. However, there is currently no method to determine the molecular weight of polycarbazole, and there is an urgent need to develop a method for determining the molecular weight of polycarbazole. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining the molecular weight of polycarbazole, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for determining the molecular weight of polycarbazole, comprising the following steps: (1) Preparation of standard solution: Dissolve polystyrene in the first solvent, let stand for 10 min, and filter through a 0.22 μm polytetrafluoroethylene filter head; (2) Preparation of test solution: Dissolve polycarbazole in the second solvent, place it in a 40℃ ultrasonic bath and sonicate for 20 minutes, oscillating once every 3 minutes, then let it stand at room temperature for 4 hours, filter it through a 0.22μm polytetrafluoroethylene filter head, and prepare a test solution with a mass volume fraction of 1mg / mL. (3) Establishing a standard calibration curve: The column oven temperature was set to 35℃, and chromatographic grade tetrahydrofuran containing antioxidant was introduced at a flow rate of 1.0 mL / min. The sample was separated using a chromatographic column packed with a highly cross-linked polystyrene-divinylbenzene copolymer. The components of the separated sample were sequentially passed through a differential refractive index detector at a temperature of 35℃ to obtain the retention time of the sample. Then, the standard calibration curve was obtained by fitting the logarithm of molecular weight as the ordinate and the retention time as the abscissa using the linear regression method. (4) Test the test solution: Set the column oven temperature to 35℃ and pass chromatographic grade tetrahydrofuran containing antioxidant at a flow rate of 1.0 mL / min. Use a chromatographic column packed with highly cross-linked polystyrene-divinylbenzene copolymer to separate the test solution sample. Then use a differential refractive index detector at 35℃ to detect the separated sample components and obtain a gel chromatogram. Use gel chromatography software to import the standard calibration curve obtained in step (3) and calculate the molecular weight of the test solution.

[0006] Furthermore, the molecular weight of the polystyrene is 580-6570000 Da.

[0007] Furthermore, both the first solvent and the second solvent are tetrahydrofuran.

[0008] Furthermore, the antioxidant is 2,6-di-tert-butyl-p-cresol.

[0009] Furthermore, the injection volume in both steps (3) and (4) is 20 μL.

[0010] Furthermore, in step (2), the polycarbazole is poly(9-ethylenecarbazole).

[0011] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) Polymer samples of standard solutions and test solutions of different molecular weights are separated by a chromatographic column packed with highly cross-linked polystyrene-divinylbenzene copolymer (PS-DVB). This can achieve rapid and effective separation, and the samples can be directly detected after separation without any additional steps. The operation is efficient and the analysis speed is fast.

[0012] (2) A linear relationship between the logarithm of molecular weight and retention time (i.e., a standard calibration curve) is established using a polystyrene standard solution (with known molecular weight). Accurate quantification is achieved by using a "label" with known molecular weight, thus avoiding errors caused by assuming polymer structure.

[0013] (3) The molecular weight distribution characteristics of polymers can be directly determined by the peak time, width and area in the chromatogram. The data is intuitive and easy to analyze and compare.

[0014] In summary, this invention provides a method for determining the molecular weight of polycarbazole, filling a gap in existing methods. Attached Figure Description Figure 1 The chromatograms of standard solution A and standard solution B in this application; Figure 2 This is the standard calibration curve for polystyrene in this application; Figure 3This is a gel chromatogram of the poly(9-vinylcarbazole)-1 sample solution obtained in this application. Figure 4 This is a molecular weight distribution diagram of the poly(9-ethylenecarbazole)-1 sample solution obtained in this application; Figure 5 This is a gel chromatogram of the poly(9-vinylcarbazole)-2 sample solution obtained in this application; Figure 6 This is a molecular weight distribution diagram of the poly(9-ethylenecarbazole)-2 sample solution obtained in this application; Figure 7 This is a gel chromatogram of the poly(9-vinylcarbazole)-3 sample solution obtained in this application; Figure 8 This is a molecular weight distribution diagram of the poly(9-ethylenecarbazole)-3 sample solution obtained in this application. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] Standards: Polystyrene scraper A and polystyrene scraper B with molecular weights ranging from 580 to 6,570,000 Da. The lower ends of both scraper A and scraper B are cured with a mixture of five different molecular weights of polystyrene standards. Both scraper A and scraper B are from Agilent Technologies China Ltd., batch number 0006439042, and both have serial numbers PL2010-0505.

[0017] Samples to be tested: Poly(9-ethylenecarbazole)-1, Poly(9-ethylenecarbazole)-2 and Poly(9-ethylenecarbazole)-3, Shanghai Maclean Biochemical Technology Co., Ltd., Product No.: P816971-1g, Batch No.: C17393568.

[0018] Logarithm of molecular weight (log) 10 (Mw): The logarithm of molecular weight (g / mol) to the base 10.

[0019] Example 1; (1) Take one polystyrene scraper A and one polystyrene scraper B, and place their lower ends independently into 1.5 mL sample bottles. Add 1.5 mL of tetrahydrofuran to each, let stand for 10 min, stir slowly, and observe the polystyrene dissolution at the lower ends of polystyrene scraper A and polystyrene scraper B. After complete dissolution, take them out and filter them with a 0.22 μm polytetrafluoroethylene filter head to obtain standard solution A and standard solution B.

[0020] (2) Dissolve poly(9-ethylenecarbazole)-1 in tetrahydrofuran, place it in an ultrasonic bath at 40°C and sonicate for 20 minutes, oscillating once every 3 minutes. Then let it stand at room temperature for 4 hours, filter it through a 0.22μm polytetrafluoroethylene filter head, and prepare a poly(9-ethylenecarbazole)-1 test solution with a mass-volume fraction of 1 mg / mL.

[0021] (3) The injection volume was set to 20 μL, the column oven temperature was set to 35℃, and chromatographic grade tetrahydrofuran containing 2,6-di-tert-butyl-p-cresol was introduced at a flow rate of 1.0 mL / min. A chromatographic column packed with highly cross-linked polystyrene-divinylbenzene copolymer was used to separate standard solution A and standard solution B. The components of standard solution A and standard solution B were then sequentially passed through a differential refractive index detector at 35℃. The change in signal intensity (nRIU) measured by the differential refractive index detector over time was obtained, forming a chromatogram. For details, please refer to [reference needed]. Figure 1 As shown. Figure 1 In the diagram, A represents standard solution A, and B represents standard solution B.

[0022] Table 1 below shows the data for standard solution A and standard solution B provided by the manufacturer: Table 1

[0023] according to Figure 1 The elution order and retention time of the peaks were used to calculate the logarithm of the molecular weight, corresponding to the known Mw, and the results are shown in Table 2.

[0024] Table 2

[0025] It should be noted that the known weight-average molecular weight (Mw) in Table 2 is derived from the peak molecular weight (Mp) values ​​in Table 1. This is because in GPC (gel permeation chromatography) testing, the standard curve is usually calibrated using the peak molecular weight (Mp) of the standard substance.

[0026] Based on Table 2, the known weight-average molecular weights of standard solutions A and B were fitted with their corresponding retention times. A standard calibration curve for polystyrene was obtained by plotting the logarithm of molecular weight on the ordinate and retention time on the abscissa. (See table 2 for details.) Figure 2 As shown.

[0027] Table 2 shows the chromatogram correction data points and curve fitting equations, as detailed in Table 3.

[0028] Table 3

[0029] It should be noted that K (Mark-Houwink constant) and α (Mark-Houwink exponent) are the core parameters describing the relationship between the intrinsic viscosity (η) of a polymer in solution and its molecular weight (M). The relationship is defined by the Mark-Houwink equation: η = K·Mα.

[0030] Where K is a constant related to the polymer-solvent system, reflecting the hydrodynamic volume or segment density of the polymer chain per unit molecular weight. α is a dimensionless exponent describing the conformation (shape) of the polymer chain in solution. When GPC indirectly determines molecular weight by detecting elution volume (retention time), the hydrodynamic volume (related to [η]·M) needs to be correlated with the standard calibration curve. Therefore, when testing with polystyrene as a standard, the results of both K and α values ​​need to be entered.

[0031] (4) The injection volume was set to 20 μL, the column temperature was set to 35℃, and chromatographic grade tetrahydrofuran containing 2,6-di-tert-butyl-p-cresol was introduced at a flow rate of 1.0 mL / min. The poly(9-ethylenecarbazole)-1 test solution sample was separated using a chromatographic column packed with a highly cross-linked polystyrene-divinylbenzene copolymer. The separated sample components were then detected using a differential refractive index detector at 35℃ to obtain a gel chromatogram, as shown below. Figure 3 As shown. Using gel chromatography software, import the standard calibration curve obtained in step (3) to calculate the molecular weight of the poly(9-ethylenecarbazole)-1 test solution, as shown. Figure 4 The figure shows the molecular weight distribution of the poly(9-ethylenecarbazole)-1 test solution. Figure 4 The horizontal axis represents the fitted molecular weight (g / mol), and the vertical axis on the left represents... d w / d log(M), the right vertical axis is the percentage height (representing the concentration (relative content) of different molecular weight components in the sample).

[0032] Example 2: The technical solution differs from that of Example 1 in that poly(9-ethylenecarbazole)-1 is replaced with poly(9-ethylenecarbazole)-2. Figure 5 The chromatogram of the poly(9-vinylcarbazole)-2 test solution sample is shown. Figure 6The molecular weight distribution of the poly(9-ethylenecarbazole)-1 test solution is shown in the figure.

[0033] Example 3: The technical solution differs from that of Example 1 in that poly(9-ethylenecarbazole)-1 is replaced with poly(9-ethylenecarbazole)-3. Figure 7 The chromatogram is of the poly(9-vinylcarbazole)-3 test solution sample. Figure 8 The molecular weight distribution of the poly(9-ethylenecarbazole)-3 test solution is shown in the figure.

[0034] according to Figure 3 , Figure 5 and Figure 7 The chromatographic results of the test solution are shown in Table 4 below.

[0035] Table 4

[0036] according to Figure 4 , Figure 6 and Figure 8 The molecular weight results of the solution to be tested are shown in Table 5 below.

[0037] Table 5

[0038] As demonstrated by the above examples, the molecular weight distribution characteristics of polymers can be directly determined by the peak time, width, and area in the chromatogram. The data is intuitive and easy to analyze and compare. Polymer samples of standard solutions and test solutions with different molecular weights can be separated using a chromatographic column packed with highly cross-linked polystyrene-divinylbenzene copolymer. This achieves rapid and effective separation, and the samples can be directly detected after separation without any additional steps. The operation is highly efficient and the analysis speed is fast.

[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for determining the molecular weight of polycarbazole, characterized in that, Includes the following steps: (1) Preparation of standard solution: Dissolve polystyrene in the first solvent, let stand for 10 min, and filter through a 0.22 μm polytetrafluoroethylene filter head; (2) Preparation of test solution: Dissolve polycarbazole in the second solvent, place it in a 40℃ ultrasonic bath and sonicate for 20 minutes, oscillating once every 3 minutes, then let it stand at room temperature for 4 hours, filter it through a 0.22μm polytetrafluoroethylene filter head, and prepare a test solution with a mass volume fraction of 1mg / mL. (3) Establishing a standard calibration curve: The column oven temperature was set to 35℃, and chromatographic grade tetrahydrofuran containing antioxidant was introduced at a flow rate of 1.0 mL / min. The sample was separated using a chromatographic column packed with a highly cross-linked polystyrene-divinylbenzene copolymer. The components of the separated sample were sequentially passed through a differential refractive index detector at a temperature of 35℃ to obtain the retention time of the sample. Then, the standard calibration curve was obtained by fitting the logarithm of molecular weight as the ordinate and the retention time as the abscissa using the linear regression method. (4) Test the test solution: Set the column oven temperature to 35℃ and pass chromatographic grade tetrahydrofuran containing antioxidant at a flow rate of 1.0 mL / min. Use a chromatographic column packed with highly cross-linked polystyrene-divinylbenzene copolymer to separate the test solution sample. Then use a differential refractive index detector at 35℃ to detect the separated sample components and obtain a gel chromatogram. Use gel chromatography software to import the standard calibration curve obtained in step (3) and calculate the relative molecular weight of the test solution.

2. The method for determining the molecular weight of polycarbazole according to claim 1, characterized in that, The molecular weight of the polystyrene is 580-6570000 Da.

3. The method for determining the molecular weight of polycarbazole according to claim 1, characterized in that, Both the first solvent and the second solvent are tetrahydrofuran.

4. The method for determining the molecular weight of polycarbazole according to claim 1, characterized in that, The antioxidant is 2,6-di-tert-butyl-p-cresol.

5. The method for determining the molecular weight of polycarbazole according to claim 1, characterized in that, The injection volume in steps (3) and (4) is 20 μL.

6. The method for determining the molecular weight of polycarbazole according to claim 1, characterized in that, In step (2), the polycarbazole is poly(9-ethylenecarbazole).

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