Method for measuring molecular weight of polyether amine

Abstract

The invention belongs to the technical field of molecular weight detection of high-molecular polymers, and discloses a method for determining molecular weight of polyether amine. The determination method comprises the following steps: carrying out derivatization treatment on polyether amine by adopting aromatic sulfonyl isocyanate to prepare derivatized polyether amine; the method comprises the following steps: dissolving derivatized polyether amine in a solvent to prepare a to-be-detected solution; injecting the to-be-tested liquid into a gel permeation chromatograph for testing to obtain GPC data of the to-be-tested liquid; and drawing a standard curve by using a series of polystyrene standard substances, carrying out linear fitting on the standard curve by using a polyether amine sample with known molecular weight, and processing the GPC data of the to-be-detected liquid by using the fitted standard curve to obtain the polyether amine molecular weight. The determination method provided by the invention is simple and safe to operate, high in accuracy of a detection result and high in repeatability, and can be suitable for determining the molecular weight of various polyether amines.

Description

Technical Field

[0001] The present invention belongs to the technical field of molecular weight detection of polymer polymers, and specifically relates to a method for determining the molecular weight of polyetheramine. Background Art

[0002] Polyetheramine is a kind of high molecular compound with excellent properties, and is widely used in fields such as coatings, adhesives, and elastomers. Among them, polyetheramines such as ED600, ED900, ED2003, M2070, FL1000, etc. have become preferred raw materials in many industrial applications due to their specific molecular weight ranges, functional group structures, and reaction activities.

[0003] However, there are few reports on the determination of polyetheramine at home and abroad at present. QB / T2853-2007 provides a method for determining the molecular weight of polyetheramine by gas chromatography. The Nanjing Chemical Industry Research Institute provides a method for determining the total amine value in polyetheramine. These methods have problems of large errors or complex operations when determining certain specific structures of polyetheramine. Gas chromatography is only suitable for the detection of small molecule polyetheramine, and the total amine value method cannot directly measure the molecular weight of the corresponding polyetheramine.

[0004] If gel permeation chromatography is used to directly determine polyetheramine, there are problems such as poor determination accuracy and reproducibility. The main reasons are that in the current gel permeation chromatography, common mobile phases (such as water, toluene, etc.) have poor solubility when determining polyetheramine, cannot dissolve polyetheramine well, and affect the determination results; or have high toxicity, posing challenges to the health and safety of operators and the procurement of laboratory reagents; and there are situations such as tailing, distortion, and poor reproducibility of polyetheramine signal peaks in GPC, resulting in abnormal integration results and inability to accurately determine the molecular weight of polyetheramine and many other problems.

[0005] Therefore, it is particularly important to develop a simple, safe, accurate method suitable for the determination of the molecular weights of various polyetheramines. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the above prior art. For this reason, the present invention proposes a method for determining the molecular weight of polyetheramine. The determination method provided by the present invention is simple and safe to operate, has high detection result accuracy and strong reproducibility, and can be applicable to the determination of the molecular weights of various polyetheramines.

[0007] The present invention provides a method for determining the molecular weight of polyetheramine.

[0008] Specifically, a method for determining the molecular weight of polyetheramine includes the following steps:

[0009] (1) Derivatize polyetheramine with aromatic sulfonyl isocyanate to obtain derivatized polyetheramine;

[0010] (2) Dissolve the derivatized polyetheramine prepared in step (1) in a solvent to prepare a test solution.

[0011] (3) Inject the test solution prepared in step (2) into a gel permeation chromatograph for testing to obtain the GPC data of the test solution; draw a standard curve with a series of polystyrene standards, linearly fit the standard curve with a polyetheramine sample of known molecular weight, and call the fitted standard curve to process the GPC data of the test solution to obtain the molecular weight of the polyetheramine.

[0012] In some embodiments of the present invention, in step (1), the aromatic sulfonyl isocyanate is 4-toluenesulfonyl isocyanate. Using 4-toluenesulfonyl isocyanate as a derivatizing reagent to derivatize polyetheramine, the amino group on the polyetheramine molecular chain can undergo an addition reaction with isocyanate to form a derivative containing a urea group; moreover, because the toluenesulfonyl group on 4-toluenesulfonyl isocyanate has a certain steric hindrance and electronic effect, it can significantly improve the stability and solubility of the derivatized product, which is beneficial to the subsequent preparation of the test solution and GPC determination. In addition, 4-toluenesulfonyl isocyanate is inexpensive and economical, which is conducive to popularization and use.

[0013] In some embodiments of the present invention, the molar ratio of the 4-toluenesulfonyl isocyanate to the polyetheramine is (1-3):1. This ratio can ensure that the amino groups in the polyetheramine are completely addition-polymerized by 4-toluenesulfonyl isocyanate to obtain sufficient derivatization. Since the actual molecular weight of 4-toluenesulfonyl isocyanate is 197.21, and the theoretical molecular weight range of polyetheramines such as ED600, ED900, ED2003, M2070, FL1000, D2000, FL1200, etc. is about 600-2000, in the actual operation process, to ensure complete reaction and operation convenience, it can be carried out according to the mass ratio of 4-toluenesulfonyl isocyanate to polyetheramine of (1-3):1.

[0014] In some embodiments of the present invention, in step (1), the temperature of the derivatization treatment is 5-40°C, and the time of the derivatization treatment is 20-40 min. Preferably, the temperature of the derivatization treatment is 10-40°C, and the time of the derivatization treatment is 30-40 min. By controlling the time of the derivatization treatment, the reaction is suitable for carrying out at room temperature, which not only requires no additional energy supply but also simplifies the operation.

[0015] In some embodiments of the present invention, in step (1), the polyetheramine includes one of polyetheramine ED600, polyetheramine ED900, polyetheramine ED2003, polyetheramine M2070, and polyetheramine FL1000.

[0016] In some embodiments of the present invention, in step (1), the water content of the polyetheramine is ≤ 0.5%. By controlling the water content of the polyetheramine, the reaction between water and 4-toluenesulfonyl isocyanate can be effectively avoided, the generation of by-products can be reduced, which is beneficial to improving the accuracy of the determination of the polyetheramine molecular weight.

[0017] In some embodiments of the present invention, in step (2), the solvent is tetrahydrofuran.

[0018] In some embodiments of the present invention, during the test in step (2), tetrahydrofuran is used as the mobile phase. Tetrahydrofuran is used as the solvent to dissolve the derivatized polyetheramine, and tetrahydrofuran is used as the mobile phase for gel permeation chromatography testing. Tetrahydrofuran not only has excellent solubility for the derivatized polyetheramine; but also using the same solvent can reduce the interference of the solvent on the sample and the operation error of the experimenter.

[0019] The detection method provided by the present invention first uses aromatic sulfonyl isocyanates (especially 4-toluenesulfonyl isocyanate) as derivatizing reagents to derivatize polyetheramine to obtain derivatized polyetheramine; then gel permeation chromatography is used to determine the molecular weight. The amino group of the polyetheramine reacts with the isocyanate group of the aromatic sulfonyl isocyanates to form amide bonds -CONH- and urea bonds (ureido groups) -NH-CO-NH-, thereby generating the high molecular polymer polyurea; and the aromatic sulfonyl on the aromatic sulfonyl isocyanates has certain steric hindrance and electronic effects, which can significantly improve the stability and solubility of the derivatized product. By analyzing the derivatized polyetheramine by gel permeation chromatography and determining its molecular weight, compared with directly determining the molecular weight of the polyetheramine, the solubility and stability of the test sample can be improved, and further the accuracy and repeatability of the detection results can be improved.

[0020] Using polystyrene as the GPC calibration standard can not only improve the accuracy of the calibration curve because of its wide molecular weight coverage range and narrow dispersity; but also polystyrene can be dissolved in a variety of organic solvents and has stable chemical properties, which is suitable for use with a variety of chromatographic columns.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) The method for determining the molecular weight of polyetheramine provided by the present invention introduces aromatic sulfonyl isocyanates as derivatizing reagents, so that the amino group on the polyetheramine molecular chain undergoes an addition reaction with the isocyanate to generate a derivative containing a ureido group. This derivative has high stability and detectability, which is convenient for subsequent molecular weight determination and can improve the accuracy and repeatability of the detection results.

[0023] (2) The determination method provided by the present invention has a short derivatization reaction time, mild reaction conditions, high safety, good stability of the polyetheramine product after the reaction, which is conducive to the traceability of subsequent molecular weight determination. Moreover, its operation is simple, easy to master, and the results are more direct and accurate.

[0024] (3) The determination method provided by the present invention can be applied to various types of polyetheramines, including but not limited to polyetheramine ED600, polyetheramine ED900, polyetheramine ED2003, polyetheramine M2070, polyetheramine FL1000, and has strong versatility and practicability. Description of the Drawings

[0025] Figure 1 It is a GPC comparison chart of derivatized polyetheramine M2070 and non-derivatized polyetheramine M2070 in Experimental Example 1;

[0026] Figure 2 It is a repeatability experiment chart of non-derivatized polyetheramine M2070 measured by GPC method in Experimental Example 2;

[0027] Figure 3 It is a repeatability experiment chart of derivatized polyetheramine M2070 measured by GPC method in Experimental Example 2. Detailed Embodiments

[0028] In order to make those skilled in the art more clearly understand the technical solutions described in the present invention, the following examples are listed for illustration. It should be noted that the following examples do not limit the scope of protection required by the present invention.

[0029] Unless otherwise specified, the raw materials, reagents or devices used in the following experimental examples and embodiments can be obtained from conventional commercial channels, or can be obtained by existing known methods. In addition, for those not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments manufactured by well-known manufacturers, they are all conventional products that can be purchased commercially.

[0030] The instruments and reagents used in the following experimental examples and embodiments are as follows:

[0031] (1) Instruments: GPC, analytical balance (accurate to 0.0001 g), pipette, 1.5 mL injection vial, 10 mL volumetric flask;

[0032] (2) Reagents: Tetrahydrofuran (chromatographically pure), 4-Toluenesulfonyl isocyanate (analytically pure), series of polystyrene standards (provided by Shanghai Zhenzhun Biotechnology Co., Ltd., with molecular weights of 500, 1100, 2500, 4000, 8000, 13000), polyetheramine FL1200 and polyetheramine D2000 with known molecular weights (measured by hydroxyl value method or multi-angle laser light scattering method), and series of polyetheramine samples involved in the method are all provided by Zhejiang Lukenan Chemical Co., Ltd.

[0033] Example 1

[0034] A method for determining the molecular weight of polyetheramine, comprising the following steps:

[0035] Weigh 0.03 g of polyetheramine ED600 (water content ≤ 0.5%) with an analytical balance into a 1.5 mL injection vial, add 0.03 g of 4-Toluenesulfonyl isocyanate. Immediately tighten the sample cap after addition and seal it to reduce the reaction of condensed moisture in the air with 4-Toluenesulfonyl isocyanate. Ultrasonic the 1.5 mL injection vial with the weighed sample for 3 min using an ultrasonic instrument to make it completely mixed evenly. The water temperature of the ultrasonic instrument is 20 °C, and let it stand for 30 min after ultrasonic treatment. Dissolve the sample after ultrasonic treatment with tetrahydrofuran, transfer it to a 10 mL volumetric flask, and make up the volume with tetrahydrofuran. Ultrasonic to completely dissolve the sample to obtain the sample solution to be measured. Use tetrahydrofuran (chromatographically pure) as the mobile phase, inject the sample solution to be measured into the GPC, and the injection volume is 20 μL. Use a series of polystyrene standards with molecular weights of 500, 1100, 2500, 4000, 8000, 13000 to draw the GPC molecular weight calibration curve, and linearly fit this curve with polyetheramine FL1200 (Mp molecular weight is 1234) and polyetheramine D2000 (Mp molecular weight is 2257). Call the fitted curve to process the sample to be measured to obtain the molecular weight of polyetheramine ED600.

[0036] Example 2

[0037] A method for determining the molecular weight of polyetheramine, comprising the following steps:

[0038] Weigh 0.03 g of polyetheramine ED900 (water content ≤ 0.5%) with an analytical balance into a 1.5 mL vial, add 0.06 g of 4-toluenesulfonyl isocyanate. Immediately tighten the sample cap after addition and seal it to reduce the reaction of moisture condensation in the air with 4-toluenesulfonyl isocyanate. Ultrasonic the 1.5 mL vial after weighing for 3 min with an ultrasonic instrument to make it completely mixed evenly. The water temperature of the ultrasonic instrument is 20 °C. Let it stand for 30 min after ultrasonic treatment. Dissolve the sample after ultrasonic treatment with tetrahydrofuran, transfer it to a 10 mL volumetric flask, and make up the volume with tetrahydrofuran. Let it stand or ultrasonic to completely dissolve the sample to obtain the test sample solution. Use tetrahydrofuran (chromatographically pure) as the mobile phase, inject the test sample solution into GPC, and the injection volume is 20 μL. Use a series of polystyrene standards with molecular weights of 500, 1100, 2500, 4000, 8000, and 13000 to draw the GPC molecular weight calibration curve, and linearly fit this curve with polyetheramine FL1200 (Mp molecular weight is 1234) and polyetheramine D2000 (Mp molecular weight is 2257). Call the fitted curve to process the test sample to obtain the molecular weight of polyetheramine ED900.

[0039] Example 3

[0040] A method for determining the molecular weight of polyetheramine, comprising the following steps:

[0041] Weigh 0.03 g of polyetheramine FL1000 (water content ≤ 0.5%) with an analytical balance into a 1.5 mL vial, add 0.09 g of 4-toluenesulfonyl isocyanate. Immediately tighten the sample cap after addition and seal it to reduce the reaction of moisture condensation in the air with 4-toluenesulfonyl isocyanate. Ultrasonic the 1.5 mL vial after weighing for 4 min with an ultrasonic instrument to make it completely mixed evenly. The water temperature of the ultrasonic instrument is 20 °C. Let it stand for 40 min after ultrasonic treatment. Dissolve the sample after ultrasonic treatment with tetrahydrofuran, transfer it to a 10 mL volumetric flask, and make up the volume with tetrahydrofuran. Let it stand or ultrasonic to completely dissolve the sample to obtain the test sample solution. Use tetrahydrofuran (chromatographically pure) as the mobile phase, inject the test sample solution into GPC, and the injection volume is 20 μL. Use a series of polystyrene standards with molecular weights of 500, 1100, 2500, 4000, 8000, and 13000 to draw the GPC molecular weight calibration curve, and linearly fit this curve with polyetheramine FL1200 (Mp molecular weight is 1234) and polyetheramine D2000 (Mp molecular weight is 2257). Call the fitted curve to process the test sample to obtain the molecular weight of polyetheramine EDFL1000.

[0042] Example 4

[0043] A method for determining the molecular weight of polyetheramine, comprising the following steps:

[0044] Weigh 0.03 g of polyetheramine M2070 (water content ≤ 0.5%) with an analytical balance into a 1.5 mL vial, add 0.06 g of 4-toluenesulfonyl isocyanate. Immediately tighten the sample cap after adding and seal it to reduce the reaction of water condensation in the air with 4-toluenesulfonyl isocyanate. Ultrasonic the 1.5 mL vial with the weighed sample for 3 min using an ultrasonic instrument to make it completely mixed evenly. The water temperature of the ultrasonic instrument is 30 °C. After ultrasonic treatment, let it stand for 40 min. Dissolve the sample after ultrasonic treatment with tetrahydrofuran, transfer it to a 10 mL volumetric flask, and make up the volume with tetrahydrofuran. Let it stand or ultrasonic to completely dissolve the sample to obtain the sample solution to be measured. Use tetrahydrofuran (chromatographically pure) as the mobile phase, inject the sample solution to be measured into the GPC, and the injection volume is 20 μL. Use a series of polystyrene standards with molecular weights of 500, 1100, 2500, 4000, 8000, and 13000 to draw the GPC molecular weight calibration curve, and linearly fit this curve using polyetheramine FL1200 (Mp molecular weight is 1234) and polyetheramine D2000 (Mp molecular weight is 2257). Call the fitted curve to process the sample to be measured to obtain the molecular weight of polyetheramine M2070.

[0045] Use nuclear magnetic resonance hydrogen spectroscopy to measure the molecular weights of the corresponding polyetheramines in Examples 1-4 respectively to obtain the nuclear magnetic molecular weights. Compare and analyze the data measured by the measurement method of the present invention and the data of nuclear magnetic resonance hydrogen spectroscopy. The comparison data is shown in Table 2.

[0046] Table 1 Measurement results of Examples 1-4

[0047]

[0048] As can be seen from Table 1, for the polyetheramine derivatized with 4-toluenesulfonyl isocyanate, the results measured by GPC are basically consistent with the nuclear magnetic analysis results, and its accuracy is high.

[0049] Experimental Example 1

[0050] (1) Determination and analysis of derivatized polyetheramine M2070:

[0051] Weigh 0.02 g of polyetheramine M2070 (water content ≤ 0.5%) using an analytical balance and place it in a 1.5 mL vial. Add 0.025 g of 4-toluenesulfonyl isocyanate. Immediately tighten the sample cap after addition and seal it to reduce the reaction of condensed moisture in the air with 4-toluenesulfonyl isocyanate. Ultrasonic the 1.5 mL vial containing the weighed sample for 3 min using an ultrasonic cleaner to make it completely and evenly mixed. The water temperature of the ultrasonic cleaner is 30 °C. After ultrasonic treatment, let it stand for 40 min. Dissolve the sample after ultrasonic treatment with tetrahydrofuran, transfer it to a 10 mL volumetric flask, and make up the volume with tetrahydrofuran. Let it stand or ultrasonic to completely dissolve the sample to obtain the test sample solution. Use tetrahydrofuran (chromatographically pure) as the mobile phase, inject the test sample solution into GPC for determination and analysis, and the injection volume is 20 μL.

[0052] (2) Determination and analysis of underivatized polyetheramine M2070:

[0053] Weigh 0.02 g of polyetheramine M2070 (water content ≤ 0.5%) using an analytical balance, dissolve it with tetrahydrofuran, transfer it to a 10 mL volumetric flask, and make up the volume with tetrahydrofuran. Let it stand or ultrasonic to completely dissolve the sample to obtain the test sample solution. Use tetrahydrofuran (chromatographically pure) as the mobile phase, inject the test sample solution into GPC for determination and analysis, and the injection volume is 20 μL.

[0054] Table 2 Comparison results of underivatized and derivatized polyetheramine M2070

[0055]

[0056] The GPC determination results of derivatized polyetheramine M2070 and underivatized polyetheramine M2070 are shown in Table 2, and the GPC comparison chart is as Figure 1 . From Table 2 and Figure 1 it can be seen that for polyetheramine M2070 after derivatization treatment with 4-toluenesulfonyl isocyanate, its molecular weight distribution index is narrower, the signal peak is significant, there are no phenomena such as tailing and distortion, it is easy to integrate, and its molecular weight can be better determined. While directly using GPC to determine polyetheramine M2070, its molecular weight distribution index is wide, and there is serious tailing and distortion in the polyetheramine signal peak, which will affect the integration result and cannot accurately determine the molecular weight of polyetheramine.

[0057] Experimental Example 2

[0058] Repeat the determination of underivatized polyetheramine M2070 in Experimental Example 1 three times. Figure 2 It is the repeatability experimental chart for the determination of underivatized polyetheramine M2070 by GPC method. Figure 2 The three curves in it are the GPC curves of the three determinations respectively. From Figure 2 it can be seen that the signal peak of underivatized polyetheramine M2070 has poor repeatability.

[0059] Experimental Example 3

[0060] Repeat the determination of derivatized polyetheramine M2070 in Repeated Experimental Example 1 three times. Figure 3 It is a reproducibility experimental graph of the determination of derivatized polyetheramine M2070 by the GPC method. From Figure 3 it can be seen that the GPC curves of the three determinations of derivatized polyetheramine M2070 almost completely coincide. The signal peaks of the derivatized polyetheramine M2070 have good reproducibility, and the molecular weight of polyetheramine can be measured more accurately.

[0061] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for determining the molecular weight of a polyetheramine, characterized in that, It includes the following steps: (1) Derivatize polyetheramine with aromatic sulfonyl isocyanates to obtain derivatized polyetheramine; (2) Dissolve the derivatized polyetheramine prepared in step (1) in a solvent to prepare a test solution; (3) Inject the test solution prepared in step (2) into a gel permeation chromatograph for testing to obtain the GPC data of the test solution; Draw a standard curve with a series of polystyrene standards, linearly fit the standard curve with a polyetheramine sample of known molecular weight, and call the fitted standard curve to process the GPC data of the test solution to obtain the molecular weight of the polyetheramine.

2. The measurement method according to claim 1, characterized in that, In step (1), the aromatic sulfonyl isocyanates are 4-toluenesulfonyl isocyanate.

3. The measurement method according to claim 2, characterized in that The molar ratio of the 4-toluenesulfonyl isocyanate to the polyetheramine is (1-3):

1.

4. The measurement method according to any one of claims 1-3, characterized in that, In step (1), the temperature of the derivatization treatment is 5-40°C, and the time of the derivatization treatment is 20-40 min.

5. The measurement method according to claim 4, characterized in that, In step (1), the temperature of the derivatization treatment is 10-40°C, and the time of the derivatization treatment is 30-40 min.

6. The determination method according to any one of claims 1-3, characterized in that, In step (1), the polyetheramine includes one of polyetheramine ED600, polyetheramine ED900, polyetheramine ED2003, polyetheramine M2070, polyetheramine FL1000, polyetheramine D2000, and polyetheramine FL1200.

7. The determination method according to any one of claims 1-3, characterized in that, In step (1), the water content of the polyetheramine is ≤0.5%.

8. The measurement method according to any one of claims 1 to 3, characterized in that In step (2), the solvent is tetrahydrofuran.

9. The measurement method according to claim 8, characterized in that, In step (2), during the testing process, tetrahydrofuran is used as the mobile phase.

Images