A method for regulating the molecular weight distribution of cyclic olefin polymers

Abstract

This invention provides a method for controlling the molecular weight distribution of cyclic olefin polymers. The method includes the following steps: a cyclic olefin monomer undergoes a ring-opening metathesis polymerization reaction under the catalysis of a compound catalyst system to obtain a cyclic olefin polymer; the cyclic olefin polymer is a cyclic olefin polymer with a bimodal molecular weight distribution. The technical solution of this application can effectively design and control the molecular weight distribution of cyclic olefin polymers, making its molecular weight distribution bimodal, including controlling the relative height of the bimodal peaks, the distance between the bimodal peaks, and the two peak values ​​and peak widths in the molecular weight distribution, thus showing outstanding promise in optimizing the performance of cyclic olefin polymers.

Description

Technical Field

[0001] This invention relates to the field of ring-opening metathesis polymerization technology, and in particular to a method for controlling the molecular weight distribution of cyclic olefin polymers. Background Technology

[0002] Cyclic olefin polymers (COPs) are a new type of high-value-added materials. Due to their advantages such as low density, low hygroscopicity, high transparency, and excellent processability, they are widely used in food packaging, medical materials, and optical components where strict quality standards are required. Ring-opening metathesis polymerization (ROMP) is one of the main techniques for preparing COPs, and polymers can usually be obtained under mild conditions. After the development of well-defined metal catalysts, ROMP has become a stable polymerization method with high efficiency and broad applicability to different functional groups; however, the molecular weight distribution of its products often exhibits a unimodal distribution.

[0003] As is well known, the molecular weight and dispersity of polymers It has a significant impact on its tensile and rheological properties. However, the influence of the molecular weight distribution (MWD) shape on these properties is often overlooked. Besides the width of the MWD (i.e., dispersion)... In addition to the measured properties, the shape characteristics of the material—such as the presence of asymmetry or skewness (biased towards the high molecular weight side or the low molecular weight side), the number of peaks (single peak, double peak, or multiple peaks), and the distribution characteristics of the peaks—can all significantly affect the final properties of the material.

[0004] Existing research has shown that polyethylene (PE) with a linear bimodal molecular weight distribution (MWD) can simultaneously improve crystallinity, processability, Young's modulus, and tensile strength, while maintaining ductility, compared to unimodal PE. Cyclic olefin copolymers (COCs) with a bimodal MWD can balance heat resistance, transparency, tensile properties, film-forming properties, and processing ease. These findings indicate that polymers exhibiting a bimodal molecular weight distribution are worthy of significant attention and further exploration.

[0005] However, current research and applications of bimodal MWD have significant limitations: the control range is limited (e.g., the relative height of the two peaks is difficult to control precisely), or the control methods are complex and require stringent reaction equipment, making mass production impossible and hindering industrial application. Furthermore, previous reports have not yet provided an effective method for controlling the MWD of COP. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for regulating the molecular weight distribution of cyclic olefin polymers to solve the problems in the prior art.

[0007] To achieve the above and other related objectives, the present invention is obtained through the following technical solution.

[0008] The first aspect of the present invention provides a method for regulating the molecular weight distribution of a cyclic olefin polymer, comprising the following steps: a cyclic olefin monomer undergoes a ring-opening metathesis polymerization reaction under the catalysis of a compound catalyst system to obtain a cyclic olefin polymer; wherein the cyclic olefin polymer is a cyclic olefin polymer with a bimodal molecular weight distribution.

[0009] Preferably, the cyclic olefins include one or more of norbornene and its derivatives, cyclopentene, cyclooctene, cyclobutene, and dihydrofuran.

[0010] Preferably, the composite catalyst system includes one or more of ruthenium-based catalysts (Grubbs catalysts), titanium-based catalysts, and molybdenum / tungsten-based catalysts.

[0011] More preferably, in this invention, the composite catalyst system further preferably comprises any two of the following ruthenium-based catalysts (Grubbs catalysts): Grubbs second-generation catalyst (G2), Hoveyda-Grubbs second-generation catalyst (HG2), and Grubbs third-generation catalyst (G3), and the molecular structural formulas of G3, G2, and HG2 are shown in Formula I:

[0012]

[0013] Preferably, the molar ratio of the monomer to the compound catalyst system is (60-960):1. For example, it can be 60-120:1, 120-960:1, and more preferably 120:1.

[0014] Preferably, in the ring-opening metathesis polymerization reaction, the conversion rate of the reactant monomer is 65% to 99%. More preferably, it is 78% to 99%.

[0015] Preferably, when the composite catalyst system consists of Grubbs second-generation catalyst and Grubbs third-generation catalyst, the molar number of the Grubbs second-generation catalyst accounts for 50% to 95% of the total molar number of the composite catalyst system; more preferably, the molar percentage is 75% to 95%.

[0016] This characteristic represents a very specific and important parameter range. Under the premise of maintaining a high monomer conversion rate (i.e., the reaction time cannot be too short), if the molar percentage of G2 catalyst is less than 50%, a bimodal cyclic olefin polymer cannot be obtained. This is because, under the same conditions, the polymerization rate of polymers initiated by G3 catalyst is faster. Decreasing the proportion of G2 leads to a further decrease in its relative polymerization rate. When the molar percentage of G2 catalyst is less than 50%, the significant difference in polymerization rate causes the difference in the area of ​​the two distribution peaks to become increasingly significant with increasing polymerization time. The polymer with the faster chain growth rate will dominate the molecular weight distribution peak, thus the molecular weight distribution gradually becomes unimodal.

[0017] Preferably, when the composite catalyst system is a Hoveyda-Grubbs second-generation catalyst and a Grubbs third-generation catalyst, the molar number of the Hoveyda-Grubbs second-generation catalyst accounts for 50% to 95% of the total molar number of the composite catalyst system; more preferably, the molar percentage is 75% to 95%.

[0018] This characteristic represents a very specific and important parameter range. While maintaining a high monomer conversion rate, if the molar proportion of the Hoveyda-Grubbs second-generation catalyst is less than 50%, it is impossible to obtain cyclic olefin polymers with a bimodal molecular weight distribution. This is because when HG2 and G3 are used in combination, the polymerization rate of polymers initiated by the G3 catalyst is faster under the same conditions. The decrease in the proportion of HG2 further reduces its relative polymerization rate. The significant difference in polymerization rate leads to a more pronounced difference in the areas of the two distribution peaks as polymerization time increases. The polymer with the faster chain growth rate dominates in terms of molecular weight distribution peak, thus gradually resulting in a single-peak molecular weight distribution.

[0019] Preferably, when the composite catalyst system consists of a Grubbs second-generation catalyst and a Hoveyda-Grubbs second-generation catalyst, the molar number of the Grubbs second-generation catalyst accounts for 25% to 95% of the total molar number of the composite catalyst system; more preferably, the molar percentage is 50% to 95%.

[0020] This characteristic represents a very specific and important parameter range. While maintaining a high monomer conversion rate, if the molar percentage of G2 catalyst is less than 25%, it is impossible to obtain cyclic olefin polymers with a bimodal molecular weight distribution. This is because, under the same conditions, the polymerization rate of polymers initiated by the HG2 catalyst is faster. Decreasing the G2 ratio leads to a further decrease in its relative polymerization rate. The significant difference in polymerization rate causes the difference in the areas of the two distribution peaks to become increasingly pronounced with increasing polymerization time. The polymer with the faster chain growth rate will dominate the molecular weight distribution peak, thus gradually resulting in a single-peak molecular weight distribution.

[0021] Preferably, the reaction is carried out in an oxygen-free and water-free environment.

[0022] Preferably, the reaction is carried out under a protective atmosphere, which includes one or both of nitrogen and argon.

[0023] Preferably, the reaction is carried out in a solvent, which is one or more selected from cyclopentane, hexane, cyclohexane, decane, isododecane, benzene, toluene, xylene, ethylbenzene, chlorobenzene, dichloromethane, and chloroform. None of the solvents contain water.

[0024] More preferably, it is one or more of benzene, toluene, xylene, chlorobenzene, dichloromethane, chloroform, and cyclohexane. None of the solvents contain water.

[0025] Preferably, the reaction is carried out by stirring at a rate of 400–1000 r / min. For example, the stirring rate can be 400–600 r / min or 600–1000 r / min.

[0026] Preferably, the reaction temperature is -60℃ to 50℃, more preferably -20℃.

[0027] Preferably, the reaction time is no more than 9 minutes. In ring-opening metathesis polymerization, the conversion rate of monomers gradually increases with the increase of reaction time; conversely, under the same conditions, the shorter the reaction time, the lower the conversion rate of monomers.

[0028] This invention does not impose any special restrictions on the type and source of the terminating agent; any agent well known to those skilled in the art can be used. In this invention, the terminating agent is preferably vinyl ethyl ether.

[0029] Preferably, the molar ratio of the terminator to the composite catalyst system is (200–400):1. For example, it can be (200–300):1, (200–232):1, (232–300):1, or 232:1. An excess of terminator ensures complete quenching of the ring-opening metathesis polymerization reaction; the terminator is used to quench the active sites of the catalyst in the reaction.

[0030] Preferably, the reaction is terminated within 30 to 35 minutes. Within this time range, it is possible to ensure that the active sites of different catalysts are quenched during the reaction, while avoiding side reactions caused by excessively long termination times.

[0031] Preferably, methanol is used for the washing.

[0032] Preferably, vacuum drying is used during the drying process, with a drying temperature of 35–50°C and a drying time of 20–24 hours.

[0033] A second aspect of the present invention provides a bimodal cyclic olefin polymer with a molecular weight distribution obtained by the method described above, wherein the high molecular weight peak of the cyclic olefin polymer has a number average molecular weight of 10,000 to 520,000 and a dispersibility of 1 to 3; and the low molecular weight peak has a number average molecular weight of 1,000 to 10,000 and a dispersibility of 2 to 5.

[0034] The number-average molecular weight of the high molecular weight peak of the cyclic olefin polymer can be 19,300–519,600, 19,300–344,200, or 10,000–350,000, and the dispersibility can be 1.069–2.38, 1.069–3, or 1–2.38; the number-average molecular weight of the low molecular weight peak of the cyclic olefin polymer can be 1,500–9,800, 1,500–10,000, or 1,000–9,800, and the dispersibility can be 2.15–4.11, 2.15–5, or 2–4.11.

[0035] The number-average molecular weights in this application were all obtained using GPC testing, and the detailed method is described in Example 1.

[0036] A third aspect of the present invention provides the use of the cyclic olefin polymer described above as a raw material in food packaging, medical devices, and optical components.

[0037] The beneficial effects of this invention are:

[0038] 1) The present invention completes the ring-opening metathesis polymerization reaction in one pot by using a compound catalyst. This method can effectively design and control the molecular weight distribution of cyclic olefin polymers and prepare cyclic olefin polymers (COP) with bimodal molecular weight distribution.

[0039] 2) This invention obtains COP with a bimodal molecular weight distribution by using different catalysts in combination, without the need for complex and cumbersome design and synthesis steps of novel catalysts.

[0040] 3) The regulation method provided by this invention can regulate the bimodal distribution of molecular weight, including regulating the relative height of the bimodal distribution, the distance between the bimodal distribution and the two peaks and peak widths in the molecular weight distribution, thus showing outstanding prospects in optimizing and regulating the properties of cyclic olefin polymers.

[0041] 4) The technical solution of this application can be completed within 10 minutes, which is highly efficient; it does not require complex continuous flow reaction equipment, which is simple. Attached Figure Description

[0042] Figure 1 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Example 1 of this invention.

[0043] Figure 2 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Example 2 of this invention.

[0044] Figure 3 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Example 3 of this invention.

[0045] Figure 4 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Example 4 of this invention.

[0046] Figure 5 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Example 5 of this invention.

[0047] Figure 6 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Example 6 of this invention.

[0048] Figure 7 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Example 7 of this invention.

[0049] Figure 8 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Example 8 of this invention.

[0050] Figure 9 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Example 9 of this invention.

[0051] Figure 10 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Example 10 of this invention.

[0052] Figure 11 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Example 11 of this invention.

[0053] Figure 12 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Comparative Example 1 of this invention.

[0054] Figure 13 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Comparative Example 2 of this invention.

[0055] Figure 14 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Comparative Example 3 of this invention.

[0056] Figure 15 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Comparative Example 4 of this invention.

[0057] Figure 16 The diagram shows the molecular weight distribution of the cyclic olefin polymer in Comparative Example 5 of this invention. Detailed Implementation

[0058] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0059] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0060] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0061] In this invention, a bimodal curve refers to a polymer molecular weight distribution curve obtained by GPC testing that exhibits a distinct bimodal pattern, where the height of the shorter peak is not less than 20% of the height of the taller peak; otherwise, it is considered a single peak.

[0062] In this invention, broad peaks and narrow peaks are evaluated based on dispersion (D), which is commonly used in the art. The closer the value of D is to 1, the narrower the peak shape. Moreover, broad peaks and narrow peaks are relative terms. In the following embodiments and comparative examples of this application, peaks with D ≤ 1.6 are considered narrow peaks.

[0063] Example 1

[0064] This embodiment provides a specific method for regulating the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of G2 (93.75% molar percentage) and G3 (6.25% molar percentage), and specifically includes the following steps:

[0065] 1) In an argon-protected glove box, dissolve norbornene (25.6 mg, 0.27 mmol) in 1.2 ml of anhydrous dichloromethane solvent, mix well, add to a 10 ml Schlenk bottle containing a small rotor, seal and remove, and pre-cool at -20°C for 1 hour.

[0066] Inside an argon-protected glove box, G2 (3.86 mg, 4.52 μmol) and G3 (4 mg, 4.52 μmol) were dissolved in 0.8 ml of anhydrous dichloromethane. 0.75 ml of G2 solution and 0.05 ml of G3 solution were added to a 10 ml Schlenk flask and mixed thoroughly. The molar ratio of G2 to G3 was 15:1. The flask was then sealed and placed at -20°C for 1 hour to pre-cool.

[0067] 2) Place the monomer Schlenk flask in a low-temperature (constant temperature) stirred reaction bath at -20°C and turn on the stirrer at 600 r / min. Purge the mixed solution of G2 and G3 with nitrogen for protection, and quickly inject 0.4 ml of the compound catalyst solution into the monomer Schlenk flask using a syringe.

[0068] After reacting for 5 minutes, add the terminator vinyl ether (0.1 ml, 1.05 mmol).

[0069] 3) After terminating the polymerization for 30 min, the polymer solution was precipitated in 100 mL of methanol, filtered and washed 3 times, and the product was collected and dried under vacuum at 40 °C for 20 hours to obtain the cyclic olefin polymer.

[0070] Furthermore, in this embodiment, the monomer conversion rate during the polymerization reaction time is 92.39%.

[0071] In this application, the cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by gel permeation chromatography (GPC) using an HLC-8320 gel permeation chromatograph from Tosoh Corporation, Japan. Polystyrene (PS) was used as the standard, and chromatographic grade tetrahydrofuran (THF) was used as the mobile phase at a flow rate of 1.0 mL / min and a test temperature of 40 °C. The test sample was dissolved in chromatographic grade THF at a concentration of 2.0 mg / mL. GPC characterized the molecular weight distribution curve of the sample, where the horizontal axis represents retention time in minutes (min), and the vertical axis represents the concentration signal. This signal was acquired by a differential refractive index detector and normalized to the maximum value (normalization was performed using the highest peak value as the maximum value).

[0072] For details, please see [link / details]. Figure 1 .Depend on Figure 1 It can be seen that the molecular weight distribution of the product sample in Example 1 exhibits a distinct bimodal distribution, characterized by a narrow peak at high molecular weight (D = 1.560; M... w =126500) and low molecular weight broad peaks (D=3.506; M= ...). w =8500), and the peak height at low molecular weight is lower than that at high molecular weight.

[0073] Example 2

[0074] This embodiment provides a specific method for regulating the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of G2 (87.5% molar percentage) and G3 (12.5% ​​molar percentage), and specifically includes the following steps:

[0075] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 1;

[0076] The dissolution process of catalysts G2 and G3 is exactly the same as in Example 1;

[0077] Then, take 0.7 ml of G2 solution and 0.1 ml of G3 solution and add them to a 10 ml Schlenk flask and mix well. The molar ratio of G2 to G3 is 7:1. Seal the flask and place it at -20°C for 1 hour to pre-cool.

[0078] 2) Exactly the same as Example 1.

[0079] 3) The same as in Example 1, a cyclic olefin polymer was obtained.

[0080] Furthermore, in this embodiment, the monomer conversion rate during the polymerization reaction time is 90.05%.

[0081] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 1, and the experimental results are as follows: Figure 2 As shown.

[0082] Depend on Figure 2 It can be seen that the molecular weight distribution of the product sample in Example 2 exhibits a distinct bimodal distribution, characterized by a narrow peak at high molecular weight (D = 1.461; M... w =120100) and low molecular weight broad peak (D=3.912; M= ...). w =7900).

[0083] Example 3

[0084] This embodiment provides a specific method for regulating the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of G2 (75% molar percentage) and G3 (25% molar percentage), and specifically includes the following steps:

[0085] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 1;

[0086] The dissolution process of catalysts G2 and G3 is exactly the same as in Example 1;

[0087] Then, take 0.6 ml of G2 solution and 0.2 ml of G3 solution and add them to a 10 ml Schlenk flask and mix well. The molar ratio of G2 to G3 is 3:1. Seal the flask and place it at -20°C for 1 hour to pre-cool.

[0088] 2) Exactly the same as Example 1.

[0089] 3) The same as in Example 1, a cyclic olefin polymer was obtained.

[0090] Furthermore, in this embodiment, the monomer conversion rate during the polymerization reaction time is 97.37%.

[0091] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 1, and the experimental results are as follows: Figure 3 As shown.

[0092] Depend on Figure 3 It can be seen that the molecular weight distribution of the product sample in Example 3 exhibits a distinct bimodal distribution, characterized by a narrow peak at high molecular weight (D = 1.151; M... w =66900) and low molecular weight broad peaks (D=3.764; M= ...). w =7000).

[0093] Example 4

[0094] This embodiment provides a specific method for regulating the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of G2 (50% molar percentage) and G3 (50% molar percentage), and specifically includes the following steps:

[0095] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 1;

[0096] The dissolution process of catalysts G2 and G3 is exactly the same as in Example 1;

[0097] Then, take 0.4 ml of G2 solution and 0.4 ml of G3 solution and add them to a 10 ml Schlenk flask and mix well. The molar ratio of G2 to G3 is 1:1. Seal the flask and place it at -20°C for 1 hour to pre-cool.

[0098] 2) Exactly the same as Example 1.

[0099] 3) The same as in Example 1, a cyclic olefin polymer was obtained.

[0100] Furthermore, in this embodiment, the monomer conversion rate during the polymerization reaction time is 92.51%.

[0101] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 1, and the experimental results are as follows: Figure 4 As shown.

[0102] Depend on Figure 4 It can be seen that the molecular weight distribution of the product sample in Example 4 exhibits a distinct bimodal distribution, characterized by a narrow peak at high molecular weight (D = 1.069; M... w=51200) and low molecular weight broad peaks (D=3.067; M= ...). w =7100).

[0103] Example 5

[0104] This embodiment provides a specific method for regulating the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of HG2 (50% molar percentage) and G3 (50% molar percentage), and specifically includes the following steps:

[0105] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 1;

[0106] Inside an argon-protected glove box, HG2 (2.83 mg, 4.52 μmol) and G3 (4 mg, 4.52 μmol) were dissolved in 0.8 ml of anhydrous dichloromethane, respectively. 0.4 ml of HG2 solution and 0.4 ml of G3 solution were added to a 10 ml Schlenk flask and mixed thoroughly. The molar ratio of HG2 to G3 was 1:1. The flask was sealed and placed at -20°C for 1 hour to pre-cool.

[0107] 2) Place the monomer Schlenk flask in a low-temperature (constant temperature) stirred reaction bath at -20°C and turn on the stirrer at 600 r / min. Purge the HG2 and G3 mixed solution with nitrogen for protection, and quickly inject 0.4 ml of the compound catalyst solution into the monomer Schlenk flask using a syringe.

[0108] After reacting for 1 minute, add the terminator vinyl ethyl ether (0.1 ml, 1.05 mmol).

[0109] 3) The same as in Example 1, a cyclic olefin polymer was obtained.

[0110] Furthermore, in this embodiment, the monomer conversion rate during the polymerization reaction time is 73.80%.

[0111] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 1, and the experimental results are as follows: Figure 5 As shown.

[0112] Depend on Figure 5 It can be seen that the molecular weight distribution of the product sample in Example 5 exhibits a bimodal distribution, characterized by a narrow peak at high molecular weight (D = 1.186; M... w =19300) and a broad peak at low molecular weight (D=2.326; M= ...). w =1500).

[0113] Example 6

[0114] This embodiment provides a specific method for regulating the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of HG2 (75% molar percentage) and G3 (25% molar percentage), and specifically includes the following steps:

[0115] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 5;

[0116] Inside an argon-protected glove box, HG2 (2.83 mg, 4.52 μmol) and G3 (4 mg, 4.52 μmol) were dissolved in 0.8 ml of anhydrous dichloromethane. 0.6 ml of HG2 solution and 0.2 ml of G3 solution were added to a 10 ml Schlenk flask and mixed thoroughly. The molar ratio of HG2 to G3 was 3:1. The flask was sealed and placed at -20°C for 1 hour to pre-cool.

[0117] 2) Place the monomer Schlenk flask in a low-temperature (constant temperature) stirred reaction bath at -20°C and turn on the stirrer at 600 r / min. Purge the HG2 and G3 mixed solution with nitrogen for protection, and quickly inject 0.4 ml of the compound catalyst solution into the monomer Schlenk flask using a syringe.

[0118] After reacting for 1 minute, add the terminator vinyl ethyl ether (0.1 ml, 1.05 mmol).

[0119] 3) The same as in Example 5, a cyclic olefin polymer was obtained.

[0120] Furthermore, in this embodiment, the monomer conversion rate during the polymerization reaction time is 78.00%.

[0121] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 5, and the experimental results are as follows. Figure 6 As shown.

[0122] Depend on Figure 6 It can be seen that the molecular weight distribution of the product sample in Example 6 exhibits a distinct bimodal distribution, characterized by a narrow peak at high molecular weight (D = 1.142; M... w =54400) and low molecular weight broad peak (D=3.320; M= ...). w =7800).

[0123] Example 7

[0124] This embodiment provides a specific method for regulating the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of G2 (75% molar percentage) and HG2 (25% molar percentage), and specifically includes the following steps:

[0125] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 1;

[0126] In an argon-protected glove box, HG2 (2.83 mg, 4.52 μmol) and G2 (3.86 mg, 4.52 μmol) were dissolved in 0.8 ml of anhydrous dichloromethane, respectively. 0.2 ml of HG2 solution and 0.6 ml of G2 solution were added to a 10 ml Schlenk flask and mixed thoroughly. The molar ratio of G2 to HG2 was 3:1. The flask was sealed and placed at -20°C for 1 hour to pre-cool.

[0127] 2) Place the monomer Schlenk flask in a low-temperature (constant temperature) stirred reaction bath at -20°C and turn on the stirrer at 600 r / min. Purge the mixed solution of G2 and HG2 with nitrogen for protection, and quickly inject 0.4 ml of the compound catalyst solution into the monomer Schlenk flask using a syringe.

[0128] After reacting for 30 seconds, add the terminator vinyl ether (0.1 ml, 1.05 mmol).

[0129] 3) The same as in Example 1, a cyclic olefin polymer was obtained.

[0130] Furthermore, in this embodiment, the monomer conversion rate during the polymerization reaction time is 99%.

[0131] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 1, and the experimental results are as follows: Figure 7 As shown.

[0132] Depend on Figure 7 It can be seen that the molecular weight distribution of the product sample in Example 7 exhibits a distinct bimodal distribution, characterized by two broad peaks, with the high molecular weight peak (D = 2.16; M) being the most prominent. w =325800) and low molecular weight peaks (D=3.38; M= ...). w =9800).

[0133] Example 8

[0134] This embodiment provides a specific method for regulating the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of G2 (50% molar percentage) and HG2 (50% molar percentage), and specifically includes the following steps:

[0135] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 7;

[0136] The dissolution process of G2 and HG2 catalysts is exactly the same as in Example 7; then 0.4 ml of HG2 solution and 0.4 ml of G2 solution are added to a 10 ml Schlenk flask and mixed evenly, wherein the molar ratio of G2 to HG2 is 1:1, sealed and placed at -20°C for 1 hour.

[0137] 2) Exactly the same as Example 7.

[0138] 3) The same as in Example 7, a cyclic olefin polymer was obtained.

[0139] Furthermore, in this embodiment, the monomer conversion rate during the polymerization reaction time is 99%.

[0140] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 7, and the experimental results are as follows: Figure 8 As shown.

[0141] Depend on Figure 8 It can be seen that the molecular weight distribution of the product sample in Example 8 exhibits a distinct bimodal distribution, showing two broad peaks, with the high molecular weight peak (D = 2.24; M) being the most prominent. w =344200) and low molecular weight peaks (D=2.89; M= ...). w =7800).

[0142] Example 9

[0143] This embodiment provides a specific method for regulating the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of G2 (25% molar percentage) and HG2 (75% molar percentage), and specifically includes the following steps:

[0144] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 7;

[0145] The dissolution process of HG2 and G2 catalysts is exactly the same as in Example 7;

[0146] Then, take 0.6 ml of G2 solution and 0.2 ml of HG2 solution and add them to a 10 ml Schlenk flask and mix well. The molar ratio of G2 to HG2 is 1:3. Seal the flask and place it at -20°C for 1 hour to pre-cool.

[0147] 2) Exactly the same as Example 7.

[0148] 3) The same as in Example 7, a cyclic olefin polymer was obtained.

[0149] Furthermore, the monomer conversion rate during the polymerization reaction time in this comparative example was 99%.

[0150] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 7, and the experimental results are as follows: Figure 9 As shown.

[0151] Depend on Figure 9 It can be seen that the molecular weight distribution of the product sample in Example 9 exhibits a bimodal distribution, showing two broad peaks, among which the high molecular weight peak (D = 2.38; M) is the most prominent. w =519600) and low molecular weight peaks (D=2.15; M= ...). w =5100). Among them, the height of the low molecular weight peak is 20% of that of the high molecular weight peak.

[0152] Example 10

[0153] This embodiment provides a specific method for regulating the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of G2 (87.5% molar percentage) and G3 (12.5% ​​molar percentage), and specifically includes the following steps:

[0154] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 2;

[0155] The process of dissolving and precooling catalysts G2 and G3 is exactly the same as in Example 2; wherein the molar ratio of G2 to G3 is 7:1.

[0156] 2) Except for the reaction time of 9 min, it is exactly the same as in Example 2.

[0157] 3) The same as in Example 2, a cyclic olefin polymer was obtained.

[0158] Furthermore, in this embodiment, the monomer conversion rate during the polymerization reaction time is 99%.

[0159] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 2, and the experimental results are as follows. Figure 10 As shown.

[0160] Depend on Figure 10 It can be seen that the molecular weight distribution of the product sample in Example 10 exhibits a distinct bimodal distribution, characterized by a narrow peak at high molecular weight (D = 1.60; M... w =125900) and low molecular weight broad peaks (D=3.45; M= ...). w =6600), and the peak height at low molecular weight is significantly lower than that at high molecular weight.

[0161] Example 11

[0162] This embodiment provides a specific method for regulating the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of G2 (87.5% molar percentage) and G3 (12.5% ​​molar percentage), and specifically includes the following steps:

[0163] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 2;

[0164] The process of dissolving and precooling catalysts G2 and G3 is exactly the same as in Example 2; wherein the molar ratio of G2 to G3 is 7:1.

[0165] 2) Except for the reaction time of 1 min, it is exactly the same as in Example 2.

[0166] 3) The same as in Example 2, a cyclic olefin polymer was obtained.

[0167] Furthermore, in this embodiment, the monomer conversion rate during the polymerization reaction time is 66.89%.

[0168] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 2, and the experimental results are as follows. Figure 11 As shown.

[0169] Depend on Figure 11 It can be seen that the molecular weight distribution of the product sample in Example 11 exhibits a distinct bimodal distribution, characterized by a narrow peak at high molecular weight (D = 1.21; M... w =75100) and low molecular weight broad peaks (D=4.11; M= ...). w =8500), and the two peaks are almost the same height.

[0170] Comparative Example 1

[0171] This comparative example does not use a complex catalyst system, but only a single catalyst G3, and specifically includes the following steps:

[0172] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 1;

[0173] In an argon-protected glove box, G3 (4 mg, 4.52 μmol) was dissolved in 0.8 ml of dichloromethane solvent and added to a 10 ml Schlenk bottle. The mixture was then sealed and placed at -20°C for 1 hour to pre-cool.

[0174] 2) Except for replacing the compound catalyst solution in Example 1 with a single 0.8 ml G3 catalyst, the rest is the same as in Example 1.

[0175] 3) The same as in Example 1, a cyclic olefin polymer was obtained.

[0176] Furthermore, the monomer conversion rate during the polymerization reaction time in this comparative example was 90.11%.

[0177] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 1, and the experimental results are as follows: Figure 12 As shown.

[0178] Depend on Figure 12 It can be seen that the molecular weight distribution of the product sample in Comparative Example 1 exhibits an extremely narrow unimodal distribution (D = 1.07; M... w =23481).

[0179] Comparative Example 2

[0180] This comparative example does not use a complex catalyst system, but only a single catalyst G2, and specifically includes the following steps:

[0181] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 1;

[0182] In an argon-protected glove box, G2 (3.86 mg, 4.52 μmol) was dissolved in 0.8 ml of dichloromethane solvent and added to a 10 ml Schlenk bottle. The mixture was then sealed and placed at -20°C for 1 hour to pre-cool.

[0183] 2) Except for replacing the compound catalyst solution in Example 1 with a single 0.8 ml G2 catalyst, the rest is the same as in Example 1.

[0184] 3) The same as in Example 1, a cyclic olefin polymer was obtained.

[0185] Furthermore, the monomer conversion rate during the polymerization reaction time in this comparative example was 41.17%.

[0186] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 1, and the experimental results are as follows: Figure 13 As shown.

[0187] Depend on Figure 13 It can be seen that the molecular weight distribution of the product sample in Comparative Example 2 exhibits a relatively broad unimodal distribution (D = 1.97; M... w =202400).

[0188] Comparative Example 3

[0189] This comparative example does not use a complex catalyst system, but only a single catalyst HG2, and specifically includes the following steps:

[0190] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 5;

[0191] In an argon-protected glove box, HG2 (2.83 mg, 4.52 μmol) was dissolved in 0.8 ml of dichloromethane solvent and added to a 10 ml Schlenk bottle. The mixture was then sealed and placed at -20°C for 1 hour to pre-cool.

[0192] 2) Except for replacing the compound catalyst solution in Example 5 with a single 0.8 ml HG2 catalyst and the reaction time being 30 s, the rest is the same as in Example 5.

[0193] 3) The same as in Example 5, a cyclic olefin polymer was obtained.

[0194] Furthermore, the monomer conversion rate during the polymerization reaction time in this comparative example was 99%.

[0195] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 5, and the experimental results are as follows. Figure 14 As shown.

[0196] Depend on Figure 14 It can be seen that the molecular weight distribution of the product sample in Comparative Example 3 exhibits a relatively broad unimodal distribution (D = 2.54; M... w =479600).

[0197] Comparative Example 4

[0198] This comparative example provides a specific method for controlling the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of G2 (25% molar percentage) and G3 (75% molar percentage), and specifically includes the following steps:

[0199] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 1;

[0200] The dissolution process of catalysts G2 and G3 is exactly the same as in Example 1;

[0201] Then, take 0.2 ml of G2 solution and 0.6 ml of G3 solution and add them to a 10 ml Schlenk flask. Mix well, with the molar ratio of G2 to G3 being 1:3. Seal the flask and place it at -20°C for 1 hour to pre-cool.

[0202] 2) Exactly the same as Example 1.

[0203] 3) The same as in Example 1, a cyclic olefin polymer was obtained.

[0204] Furthermore, the monomer conversion rate during the polymerization reaction time in this comparative example was 95.45%.

[0205] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 1, and the experimental results are as follows: Figure 15 As shown.

[0206] Depend on Figure 15 It can be seen that the molecular weight distribution of the product sample in Comparative Example 4 exhibits a unimodal distribution (D = 1.15; M... w =36100).

[0207] Comparative Example 5

[0208] This comparative example provides a specific method for controlling the molecular weight distribution of cyclic olefin polymers, wherein the composite catalyst system consists of HG2 (25% molar percentage) and G3 (75% molar percentage), and specifically includes the following steps:

[0209] 1) The process of dissolving and precooling norbornene is exactly the same as in Example 5;

[0210] The dissolution process of HG2 and G3 catalysts is exactly the same as in Example 5;

[0211] Then, take 0.2 ml of HG2 solution and 0.6 ml of G3 solution and add them to a 10 ml Schlenk flask. Mix well, with the molar ratio of HG2 to G3 being 1:3. Seal the flask and place it at -20°C for 1 hour to pre-cool.

[0212] 2) Exactly the same as Example 5.

[0213] 3) The same as in Example 5, a cyclic olefin polymer was obtained.

[0214] Furthermore, the monomer conversion rate during the polymerization reaction time in this comparative example was 73.61%.

[0215] The cyclic olefin polymer was dissolved in chromatographic grade THF and characterized by GPC. The specific experimental procedures were the same as in Example 5, and the experimental results are as follows. Figure 16 As shown.

[0216] Depend on Figure 16 It can be seen that the molecular weight distribution of the product sample in Comparative Example 5 exhibits a unimodal distribution (D = 1.14; M... w =15900).

[0217] Depend on Figures 1 to 11 It can be seen that the molecular weight distribution of the cyclic olefin polymers prepared in Examples 1 to 11 of this application all exhibit a bimodal distribution, indicating that the method provided by the technical solution of this application can achieve the control of the molecular weight distribution of the cyclic olefin polymer, so that it exhibits the desired bimodal distribution.

[0218] Depend on Figures 1-4It is known that when using a combination of Grubbs second-generation catalyst (G2) and Grubbs third-generation catalyst (G3), when the molar amount of G2 accounts for 50% or more of the total molar amount of the combined catalyst system, cyclic olefin polymers with a bimodal molecular weight distribution can be prepared. Furthermore, when the molar amount of G2 accounts for more than 75% of the total molar amount of the combined catalyst system, the bimodality is more pronounced. However, when the molar amount of G2 accounts for 50% of the total molar amount of the combined catalyst system, the molecular weight distribution becomes less pronounced. Figure 4 It can be seen that there is a significant difference in the relative height between the two peaks, exhibiting a weak bimodal shape. This may be because, under the same conditions, the polymerization rate of the polymer species initiated by catalyst G2 is slower than that initiated by catalyst G3. The reduction in the proportion of G2 will lead to a further decrease in its relative polymerization rate, which in turn leads to a significant difference in the relative height between the two peaks, exhibiting a weak bimodal shape.

[0219] Depend on Figure 2 and Figures 10-11 As can be seen, reaction time is one of the important parameters for controlling the bimodal distribution in the technical solution of this application. When all other conditions are kept the same, when using a combination of Grubbs second-generation catalyst (G2) and Grubbs third-generation catalyst (G3), as the reaction time increases, the relative height of the peak at the low molecular weight gradually decreases, and the two peaks gradually change from a highly similar state to a state with distinct high and low peaks, that is, the peak height at the high molecular weight is significantly greater than the peak height at the low molecular weight.

[0220] Depend on Figure 5 and Figure 6 It is known that when Grubbs third-generation catalyst (G3) and Hoveyda-Grubbs second-generation catalyst (HG2) are combined, cycloolefin polymers with a bimodal molecular weight distribution can be prepared when the molar amount of HG2 accounts for 50% or more of the total molar amount of the combined catalyst system. Furthermore, the bimodality is more pronounced when the molar amount of HG2 accounts for more than 75% of the total molar amount of the combined catalyst system. However, when the molar amount of HG2 accounts for 50% of the total molar amount of the combined catalyst system, the molecular weight distribution becomes less pronounced. Figure 5 It can be seen that the separation between the two peaks is weak, and they can only show a faint double-peak shape.

[0221] Depend on Figures 7-9 It is known that when Grubbs second-generation catalyst (G2) and Hoveyda-Grubbs second-generation catalyst (HG2) are combined, when the molar amount of G2 accounts for 25% or more of the total molar amount of the combined catalyst system, cyclic olefin polymers with a bimodal molecular weight distribution can be prepared. Furthermore, when the molar amount of G2 accounts for more than 50% of the total molar amount of the combined catalyst system, the bimodality is more pronounced. However, when the molar amount of G2 accounts for 25% of the total molar amount of the combined catalyst system, the molecular weight distribution becomes less pronounced. Figure 9It can be seen that the separation between the two peaks is weak, and they can only show a faint double-peak shape.

[0222] Depend on Figure 1 , 5 As shown in 12-14, compared with Example 1, when G2 and G3 are used alone, the molecular weight distribution of the prepared cyclic olefin polymers is uniformly unimodal; compared with Example 5, when HG2 is used alone, the molecular weight distribution of the prepared cyclic olefin polymers is also uniformly unimodal. This demonstrates that bimodal cyclic olefin polymers can only be prepared by using the compound catalyst system in the technical solution of this application, combined with other technical means.

[0223] Depend on Figure 1 and Figure 15 It can be seen that, compared with Example 1, when the composite catalyst system is G2 (25% molar percentage) and G3 (75% molar percentage), the molecular weight distribution of the cyclic olefin polymer prepared in Comparative Example 4 shows an obvious single-peak shape.

[0224] Depend on Figure 5 and Figure 16 It can be seen that, compared with Example 5, when the composite catalyst system is HG2 (25% molar percentage) and G3 (75% molar percentage), the molecular weight distribution of the cyclic olefin polymer prepared in Comparative Example 5 shows an obvious single-peak shape.

[0225] This indicates that bimodal cyclic olefin polymers can only be prepared within the proportion range of the compound catalyst system provided in this application, while ensuring a good monomer conversion rate.

[0226] In existing technologies, COP with a single-peak low molecular weight distribution exhibits excellent processing performance (low viscosity, easy flow), but its mechanical strength, toughness, and heat resistance (T) are relatively low. g Slightly lower), with significantly reduced resistance to environmental stress cracking, making it unable to meet high-performance requirements; while COP with a single-peak high molecular weight distribution has excellent final mechanical and thermal properties, but its melt viscosity is extremely high, making processing extremely difficult (high temperature, high pressure, high energy consumption, and difficulty in molding complex or thin-walled products), and its internal stress is large.

[0227] The bimodal cyclic olefin polymer obtained through the technical solution of this application significantly reduces the overall viscosity and improves processability by introducing low molecular weight components, while retaining a sufficient number of high molecular weight components to maintain the high strength, high toughness, and high T required by the material. g Key properties such as molecular weight distribution are also achieved. Furthermore, by controlling the bimodal shape, an optimized balance can be achieved between the heat resistance, transparency, tensile properties, and processability of cyclic olefin polymers. Therefore, the bimodal cyclic olefin polymers provided in this application have a very broad prospect in polymer applications.

[0228] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method of modulating the molecular weight distribution of a cyclic olefin polymer, characterized by, The method comprises the following steps: The ring olefin is subjected to ring-opening metathesis polymerization under the catalysis of a complex catalyst system to obtain a ring olefin polymer; the ring olefin polymer is a ring olefin polymer with a bimodal molecular weight distribution; The ring olefin comprises one or more of norbornene and its derivatives, cyclopentene, cyclooctene, cyclobutene and dihydrofuran; The molar ratio of the monomer to the complex catalyst system is (60-960):1; In the ring-opening metathesis polymerization, the conversion rate of the monomer is 65%-99%; The complex catalyst system is selected from any two of the following ruthenium-based catalysts: Grubbs second-generation catalyst, Hoveyda-Grubbs second-generation catalyst and Grubbs third-generation catalyst; When the complex catalyst system is the Grubbs second-generation catalyst and the Grubbs third-generation catalyst, the number of moles of the Grubbs second-generation catalyst accounts for 50%-95% of the total number of moles of the complex catalyst system; When the complex catalyst system is the Hoveyda-Grubbs second-generation catalyst and the Grubbs third-generation catalyst, the number of moles of the Hoveyda-Grubbs second-generation catalyst accounts for 50%-95% of the total number of moles of the complex catalyst system; When the complex catalyst system is the Grubbs second-generation catalyst and the Hoveyda-Grubbs second-generation catalyst, the number of moles of the Grubbs second-generation catalyst accounts for 25%-95% of the total number of moles of the complex catalyst system.

2. The method of claim 1, wherein, When the complex catalyst system is the Grubbs second-generation catalyst and the Grubbs third-generation catalyst, the number of moles of the Grubbs second-generation catalyst accounts for 75%-95% of the total number of moles of the complex catalyst system; When the complex catalyst system is the Hoveyda-Grubbs second-generation catalyst and the Grubbs third-generation catalyst, the number of moles of the Hoveyda-Grubbs second-generation catalyst accounts for 75%-95% of the total number of moles of the complex catalyst system; When the complex catalyst system is the Grubbs second-generation catalyst and the Hoveyda-Grubbs second-generation catalyst, the number of moles of the Grubbs second-generation catalyst accounts for 50%-95% of the total number of moles of the complex catalyst system.

3. The method of claim 1, wherein, The reaction is carried out in an oxygen-free and water-free environment; The reaction is carried out in a protective atmosphere, which comprises one or both of nitrogen and argon; The reaction is carried out in a solvent, which is one or more of cyclopentane, hexane, cyclohexane, decane, isododecane, benzene, toluene, xylene, ethylbenzene, chlorobenzene, dichloromethane and chloroform; The reaction is carried out with stirring at a stirring rate of 400-1000 r / min; The reaction temperature is -60°C-50°C, The reaction time is not more than 9 minutes; The reaction is terminated by adding a termination agent; The ring-opening metathesis polymerization is followed by a post-treatment step, which comprises filtration, washing and drying.

4. The method of claim 3, wherein, The terminating agent comprises vinyl ethyl ether; And / or, the molar ratio of the terminating agent to the complex catalyst system is (200-400):1; And / or, the time for terminating the reaction is 30-35 minutes.

5. The method of claim 3, wherein, The washing is performed by using methanol; And / or, the drying is performed by using vacuum drying, and the drying temperature is 35-50℃.

6. The cycloolefin polymer having a bimodal molecular weight distribution obtained by the process according to any one of claims 1 to 5, characterized in that The number average molecular weight of the high molecular weight peak of the cyclic olefin polymer is 10,000-520,000, and the dispersity is 1-3; the number average molecular weight of the low molecular weight peak is 0.1-10,000, and the dispersity is 2-5.

7. Use of the cyclic olefin polymer according to claim 6 as a raw material in food packaging, medical devices and optical elements.

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