Cycloolefin terpolymer and its preparation method and application

Abstract

The application discloses a cyclic olefin terpolymer and a preparation method and application thereof. The cyclic olefin terpolymer is obtained by polymerization of ethylene monomers, cyclic olefin monomers and carbazole-containing cyclic olefin monomers, wherein the ethylene monomers account for 40-70% of the mole number of the cyclic olefin terpolymer, the cyclic olefin monomers account for 20-50%, and the carbazole-containing cyclic olefin monomers account for 1-20%. The application introduces the carbazole-containing cyclic olefin monomers into the cyclic olefin terpolymer, improves the reaction activity matching of the functional monomers and the cyclic olefin monomers, and makes the obtained copolymer have high refractive index, high glass transition temperature and good transparency, and can be used for optical materials.

Description

Technical Field

[0001] This application relates to the field of functionalized polyolefin technology, specifically to a cyclic olefin terpolymer, its preparation method, and its application. Background Technology

[0002] Cyclic olefin copolymers are a class of amorphous thermoplastic resins obtained by copolymerizing ethylene or α-olefins with cyclic olefin monomers under the action of a catalyst. Due to their high transparency, low birefringence, low water absorption, and good heat resistance, they have been widely used in optical lenses, display devices, medical packaging, and other fields. However, the refractive index of traditional cyclic olefin copolymers is usually only 1.53~1.54, which is difficult to meet the requirements of high-end optical materials for high refractive index.

[0003] In existing technologies, to improve the refractive index of cyclic olefin copolymers, high-molar-refractive-index aromatic groups such as carbazole and fluorene are typically linked to α-olefins via flexible methylene chains to form α-olefin-type functional monomers, which are then ternarily copolymerized with ethylene and cyclic olefin monomers. However, the significant difference in double-bond reactivity between these functional monomers and cyclic olefin monomers can easily lead to a mismatch in polymerization rates, limiting the synergistic insertion of functional monomers and cyclic olefin monomers. Simultaneously, the flexible spacer chains increase the free volume and segment mobility of the polymer backbone, which is detrimental to maintaining a high glass transition temperature. Therefore, it remains difficult to simultaneously achieve both high refractive index and high heat resistance. Summary of the Invention

[0004] This application addresses the technical problem of simultaneously improving the refractive index and heat resistance of cyclic olefin copolymers by providing a cyclic olefin terpolymer, its preparation method, and its application in optical materials. This cyclic olefin terpolymer, through the introduction of carbazole-containing cyclic olefin monomers, combines the carbazole group with the cyclic olefin structure, which improves the reactivity matching between the functional monomers and the cyclic olefin monomers during copolymerization, and maintains a high glass transition temperature and thermal stability while increasing the material's refractive index.

[0005] To achieve the above objectives, this application adopts the following technical solution: The first aspect of this application provides a cyclic olefin terpolymer having the structure of Formula I:

[0006] In this context, x represents 40% to 70% of the total number of moles of all structural units, y represents 20% to 50% of the total number of moles of all structural units, and z represents 1% to 20% of the total number of moles of all structural units; p is 0 or 1; q is 0 or 1; 20 ≤ n ≤ 5000.

[0007] Furthermore, the cyclic olefin terpolymer is any one of the following formulas: .

[0008] Furthermore, the weight-average molecular weight of the cyclic olefin terpolymer is 5~600kDa; the glass transition temperature is 162~189℃; and the 5wt% thermal weight loss temperature is 428~436℃.

[0009] A second aspect of this application provides a method for preparing the cyclic olefin terpolymer as described above, comprising: In an inert solvent, a cyclic olefin monomer, a carbazole-containing cyclic olefin monomer having the structure of formula II, and an ethylene monomer are polymerized in the presence of a catalyst to obtain a cyclic olefin terpolymer having the structure of formula I. Among them, the carbazole-containing cyclic olefin monomers with the structure of Formula II are shown below:

[0010] Where q is 0 or 1.

[0011] Furthermore, the cyclic olefin monomer is norbornene or tetracyclododecene.

[0012] Furthermore, the carbazole-containing cyclic olefin monomer having the structure of Formula II is selected from either Formula e or Formula f: .

[0013] Furthermore, the molar ratio of the catalyst to the cyclic olefin monomer is 1:(500~5000). The molar ratio of the catalyst to the carbazole-containing cyclic olefin monomer having the structure of Formula II is 1: (50~2500).

[0014] Furthermore, the catalyst is a metallocene catalyst, which is any one of the following: ethyl-bridged bis(indene) zirconium chloride catalyst, dimethylsilyl-bridged bis(indene) zirconium chloride catalyst, isopropylidene-bridged fluorene zirconium chloride catalyst, diphenylmethylene-bridged fluorene zirconium chloride catalyst, and diphenylmethylene-bridged 2,7-di-tert-butylfluorene zirconium chloride catalyst.

[0015] Furthermore, the polymerization reaction temperature is 30~120℃, and the polymerization reaction time is 5~240min.

[0016] The third aspect of this application provides the application of the cyclic olefin terpolymer as described above, or the cyclic olefin terpolymer prepared by the above preparation method, in optical materials.

[0017] Compared with the prior art, this application has the following beneficial effects: This application introduces carbazole-containing cyclic olefin monomer units into the polymer structure based on ethylene and cyclic olefin monomer units, allowing the carbazole group to enter the polymer structure in a rigid ring-linked manner. The carbazole group has a high molar refractive index, which can effectively increase the refractive index of the cyclic olefin copolymer. Simultaneously, the rigid cyclic olefin linkage structure avoids the adverse effects of flexible methylene chains increasing the free volume of the polymer backbone and the mobility of chain segments. This allows the resulting cyclic olefin terpolymer to maintain a high glass transition temperature and thermal stability while increasing the refractive index, thus improving the problem of traditional cyclic olefin copolymers struggling to simultaneously achieve high refractive index and high heat resistance.

[0018] This application employs a copolymerization reaction of cyclic olefin monomers, carbazole-containing cyclic olefin monomers with Formula II, and ethylene monomers in the presence of a catalyst. The double bond reactivity of the carbazole-containing cyclic olefin monomers is more compatible with that of cyclic olefin monomers such as norbornene and tetracyclododecene, which helps to reduce the adverse effects of the difference in the polymerization rates of the three monomers on the control of the copolymer composition. This improves the insertion capability of the carbazole functional monomer without sacrificing the insertion of the cyclic olefin monomer, thereby obtaining a cyclic olefin terpolymer with high refractive index, high heat resistance, and good transparency.

[0019] The cyclic olefin terpolymer obtained in this application combines the increased refractive index brought by the carbazole structure, the rigid heat resistance characteristics brought by the cyclic olefin structure, and the transparency of the cyclic olefin copolymer itself. The refractive index of this material can reach 1.60, and it can maintain a high glass transition temperature and light transmittance, which can meet the comprehensive requirements of optical materials for high refractive index, transparency and heat resistance. It is suitable for optical materials fields such as optical resins, optical lenses, and display devices. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a DSC curve of the cyclic olefin terpolymer obtained in Example 1 of the present invention; Figure 2 This is the visible light transmittance curve of the cyclic olefin terpolymer obtained in Example 2 of the present invention.

[0022] All chemical structural formulas in this patent application were drawn using InDraw Molecule Editor (integle.com). Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] In one embodiment of this application, the cyclic olefin terpolymer has the structure of Formula I:

[0025] In this context, x represents 40% to 70% of the total number of moles of all structural units, y represents 20% to 50% of the total number of moles of all structural units, and z represents 1% to 20% of the total number of moles of all structural units; p is 0 or 1; q is 0 or 1; 20 ≤ n ≤ 5000.

[0026] As a specific example, a cyclic olefin terpolymer is any one of the following formulas: .

[0027] In some embodiments of this application, the weight-average molecular weight of the cyclic olefin terpolymer is 5-600 kDa, more preferably 50-180 kDa. This molecular weight range is beneficial for maintaining the polymer's processability and film-forming properties.

[0028] In one embodiment of this application, a method for preparing a cyclic olefin terpolymer is provided, comprising: in an inert solvent, a cyclic olefin monomer, a carbazole-containing cyclic olefin monomer having the structure of formula (II) and an ethylene monomer are polymerized in the presence of a catalyst to obtain a cyclic olefin terpolymer having the structure of formula (I); Among them, the carbazole-containing cyclic olefin monomers with the structure of Formula II are shown below:

[0029] Where q is 0 or 1.

[0030] In some embodiments of this application, the cyclic olefin monomer is norbornene or tetracyclododecene. The introduction of rigid ring structures into the polymer chain during copolymerization of norbornene or tetracyclododecene is beneficial for increasing the glass transition temperature of the resulting cyclic olefin terpolymer.

[0031] In some embodiments of this application, the carbazole-containing cyclic olefin monomer having the structure of Formula II is selected from either Formula e or Formula f: .

[0032] The carbazole structure possesses a high molar refractive index, and its introduction into cyclic olefin copolymers is beneficial for improving the refractive index of the resulting resin. Compared to carbazole functional monomers linked to α-olefins via flexible methylene chains, this application directly links the carbazole group to the ring of the cyclic olefin monomer. This makes the double bond reactivity of the carbazole-containing cyclic olefin monomer with the Formula II structure more compatible with that of the cyclic olefin monomer, thereby significantly improving the insertion capability of the carbazole functional monomer without sacrificing the cyclic olefin insertion, thus achieving a balance between refractive index enhancement and heat resistance maintenance.

[0033] In some embodiments of this application, the molar ratio of the catalyst to the cyclic olefin monomer is 1:(500~5000), preferably 1:(800~3000); the molar ratio of the catalyst to the carbazole-containing cyclic olefin monomer having the structure of Formula II is 1:(50~2500), preferably 1:(200~2000). By controlling the amount of catalyst relative to the cyclic olefin monomer and the carbazole-containing cyclic olefin monomer, the matching relationship between the active center and the polymerizable monomer in the polymerization system can be adjusted, enabling the effective copolymerization of ethylene, the cyclic olefin monomer, and the carbazole-containing cyclic olefin monomer under the action of a metallocene catalyst.

[0034] In some embodiments of this application, the inert solvent can be a straight-chain hydrocarbon compound, a cyclic hydrocarbon compound, or an aromatic hydrocarbon compound, preferably a benzene compound, and more preferably toluene. The inert solvent is used to dissolve or disperse cyclic olefin monomers, carbazole-containing cyclic olefin monomers, and catalysts, and to provide a reaction medium for the copolymerization of ethylene, enabling the monomers to undergo addition copolymerization under the action of a metallocene catalyst.

[0035] In some embodiments of this application, the catalyst is a metallocene catalyst, which has excellent co-catalytic ability and is beneficial for improving the copolymerization reaction activity. The metallocene catalyst is selected from ethyl-bridged bis(indene) zirconium chloride catalyst (Cat1), dimethylsilyl-bridged bis(indene) zirconium chloride catalyst (Cat2), isopropylidene-bridged fluorene-zirconium chloride catalyst (Cat3), diphenylmethylene-bridged fluorene-zirconium chloride catalyst (Cat4), and diphenylmethylene-bridged 2,7-di-tert-butylfluorene-zirconium chloride catalyst (Cat5).

[0036] As an example, metallocene catalysts can be used in combination with other catalysts, with the metallocene catalyst acting as the main catalyst and the other catalysts acting as co-catalysts, such as methylaluminoxane.

[0037] In some embodiments of this application, the polymerization reaction can be carried out in a reactor filled with ethylene gas, with ethylene gas continuously introduced into the reactor. The ethylene pressure can be maintained at 1 atmosphere to 5 atmospheres. As examples, the ethylene pressure can be maintained at 1 atmosphere, 3 atmospheres, and 5 atmospheres. The polymerization temperature can be 30~120°C, and the polymerization time can be 5~240 min. As examples, the polymerization temperature can be 30°C, 40°C, 55°C, 70°C, 90°C, and 120°C; and the polymerization time can be 5 min, 10 min, 60 min, 100 min, 150 min, and 240 min. The polymerization temperature and polymerization time are used to control the monomer insertion and chain growth process, so that the ethylene monomer, cyclic olefin monomer, and carbazole-containing cyclic olefin monomer form the cyclic olefin terpolymer structure shown in Formula I under the action of a catalyst.

[0038] In one embodiment of this application, after the polymerization reaction is completed, the polymerization reaction solution is post-treated. Specifically, the polymerization reaction solution is mixed with a hydrochloric acid-ethanol solution to terminate the polymerization chain growth and obtain the reaction product; then, the reaction product is subjected to solid-liquid separation, washing, and drying to obtain a cyclic olefin terpolymer. This application does not have any particular limitation on the method for terminating the polymerization chain growth; the above-mentioned method of mixing the reaction solution with a hydrochloric acid-ethanol solution can be used, where the volume fraction of the hydrochloric acid-ethanol solution can be 5% to 15%; solid-liquid separation can be performed by filtration; the washing reagent can be ethanol, and the washing frequency is preferably two times; there are no particular limitations on the drying method, and any drying technique well known to those skilled in the art can be used, with vacuum drying being the preferred method, the drying temperature being 50 to 80°C, and the drying time being 16 to 24 hours. The above post-treatment process is beneficial for terminating the growth of residual active chains, removing residual monomers, catalysts, and solvents, so that the obtained polymer meets the requirements for subsequent performance testing and optical material applications.

[0039] In some embodiments of this application, the obtained cyclic olefin terpolymer can be used in optical materials. The cyclic olefin terpolymer combines the refractive index enhancement provided by the carbazole structure, the rigidity and heat resistance provided by the cyclic olefin structure, and the transparency of the cyclic olefin copolymer itself, making it suitable for optical materials where transparency, refractive index, and heat resistance are required.

[0040] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0041] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under standard conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications in the art, unless otherwise stated.

[0042] Example 1 In this embodiment, firstly, a 75 mL glass pressure reactor connected to the gas pipeline was vacuum dried at 110 °C for 1 h, and the process was repeated three times with vacuuming and nitrogen purging, followed by three purgings with ethylene. The system temperature was then set to 90 °C. Subsequently, under a nitrogen atmosphere, 2.5 mL of a 1 mol / L solution of toluene-based co-catalyst methylaluminoxane (MAO), 8 mL of toluene, 0.47 g of norbornene, and 1.36 g of carbazole-containing cyclic olefin monomer e were added to the reactor. Then, 5.0 μmol of diphenylmethylene-bridged fluorene-containing zirconium dichloride catalyst (Cat4) was dissolved in 2 mL of toluene and injected into the polymerization system via a syringe. Polymerization was carried out under rapid stirring at 500 rpm, with ethylene introduced and maintained at a pressure of 1 bar. After 10 min, the pressure reactor was emptied, 200 mL of hydrochloric acid-ethanol was added to quench the polymerization reaction, the polymer was filtered, and dried to constant weight in a vacuum oven to obtain 1.47 g of the cyclic olefin terpolymer.

[0043] The weight-average molecular weight of the cyclic olefin terpolymer obtained in this embodiment was 159 kDa, and the molecular weight distribution was 2.3. Figure 1 As shown in the figure, the glass transition temperature of the cyclic olefin terpolymer obtained in this embodiment is 162°C, the temperature at which it loses 5 wt% of its weight is 435°C, the refractive index is 1.58, and the light transmittance is 91.6%.

[0044] Example 2 In this embodiment, firstly, a 75 mL glass pressure reactor connected to the gas pipeline was vacuum dried at 110 °C for 1 h, and the process was repeated three times with vacuuming and nitrogen purging, followed by three purgings with ethylene. The system temperature was then set to 90 °C. Subsequently, under a nitrogen atmosphere, 2.5 mL of a 1 mol / L MAO cocatalyst solution prepared from toluene, 8 mL of toluene, 0.8 g of tetracyclododecene, and 1.36 g of carbazole-containing cyclic olefin monomer e were added to the reactor. Then, 5.0 μmol of Cat4 was dissolved in 2 mL of toluene and injected into the polymerization system using a syringe. Polymerization was carried out under rapid stirring at 500 rpm, with ethylene introduced and the ethylene pressure maintained at 1 bar. After 10 min, the pressure reactor was emptied, 200 mL of hydrochloric acid-ethanol was added to quench the polymerization reaction, the polymer was filtered, and dried to constant weight in a vacuum oven to obtain 1.76 g of the cyclic olefin terpolymer.

[0045] The cyclic olefin terpolymer obtained in this embodiment has a weight-average molecular weight of 143 kDa, a molecular weight distribution of 2.2, a glass transition temperature of 178°C, a 5 wt% thermal weight loss temperature of 436°C, and a refractive index of 1.60, as tested. Figure 2 As shown in the figure, the light transmittance of the cyclic olefin terpolymer obtained in this embodiment is 90.5%.

[0046] Example 3 In this embodiment, firstly, a 75 mL glass pressure reactor connected to the gas pipeline was vacuum dried at 110 °C for 1 h, and the process was repeated three times with vacuuming and nitrogen purging, followed by three purgings with ethylene. The system temperature was then set to 90 °C. Subsequently, under a nitrogen atmosphere, 2.5 mL of a 1 mol / L MAO cocatalyst solution prepared from toluene, 8 mL of toluene, 0.47 g of norbornene, and 1.69 g of carbazole-containing cyclic olefin monomer f were added to the reactor. Then, 5.0 μmol of Cat4 was dissolved in 2 mL of toluene and injected into the polymerization system using a syringe. Polymerization was carried out under rapid stirring at 500 rpm, with ethylene introduced and the ethylene pressure maintained at 1 bar. After 10 min, the pressure reactor was emptied, 200 mL of hydrochloric acid-ethanol was added to quench the polymerization reaction, the polymer was filtered, and dried to constant weight in a vacuum oven to obtain 1.93 g of the cyclic olefin terpolymer.

[0047] According to the test results, the weight-average molecular weight of the cyclic olefin terpolymer obtained in this embodiment is 126 kDa, the molecular weight distribution is 2.2, the glass transition temperature is 174℃, the temperature of 5 wt% thermal weight loss is 428℃, the refractive index is 1.58, and the light transmittance is 90.1%.

[0048] Example 4 In this embodiment, firstly, a 75 mL glass pressure reactor connected to the gas pipeline was vacuum dried at 110 °C for 1 h, and the process was repeated three times with vacuuming and nitrogen purging, followed by three purgings with ethylene. The system temperature was then set to 90 °C. Subsequently, under a nitrogen atmosphere, 2.5 mL of a 1 mol / L MAO cocatalyst solution prepared from toluene, 8 mL of toluene, 0.8 g of tetracyclododecene, and 1.69 g of carbazole-containing cyclic olefin monomer f were added to the reactor. Then, 5.0 μmol of Cat4 was dissolved in 2 mL of toluene and injected into the polymerization system using a syringe. Polymerization was carried out under rapid stirring at 500 rpm, with ethylene introduced and the ethylene pressure maintained at 1 bar. After 10 min, the pressure reactor was emptied, 200 mL of hydrochloric acid-ethanol was added to quench the polymerization reaction, the polymer was filtered, and dried to constant weight in a vacuum oven to obtain 2.06 g of the cyclic olefin terpolymer.

[0049] According to the test results, the weight-average molecular weight of the cyclic olefin terpolymer obtained in this embodiment is 114 kDa, the molecular weight distribution is 2.2, the glass transition temperature is 189℃, the temperature of 5 wt% thermal weight loss is 431℃, the refractive index is 1.59, and the light transmittance is 91.1%.

[0050] Comparative Example 1 The main difference between this comparative example and Examples 1 and 3 is that the carbazole-containing cyclic olefin monomer e was not added; instead, 0.94 g of norbornene was used in the ethylene copolymerization. Specifically, a 75 mL glass pressure reactor connected to the gas pipeline was first vacuum-dried at 110 °C for 1 h, and then repeatedly evacuated and purged with nitrogen three times, followed by purging with ethylene three times. The system temperature was then set to 90 °C. Subsequently, under a nitrogen atmosphere, 2.5 mL of a 1 mol / L MAO co-catalyst solution prepared from toluene, 8 mL of toluene, and 0.94 g of norbornene were added to the reactor. Then, 5.0 μmol of diphenylmethylene-bridged fluorene-containing zirconium dichloride catalyst (Cat4) was dissolved in 2 mL of toluene and injected into the polymerization system using a syringe. Ethylene was introduced while stirring at 500 rpm and the ethylene pressure was maintained at 1 bar. After 10 minutes, the pressure reactor was emptied, 200 mL of hydrochloric acid ethanol was added to quench the polymerization reaction, the polymer was filtered, and dried in a vacuum oven to constant weight to obtain 1.46 g of cyclic olefin copolymer.

[0051] The cyclic olefin copolymer obtained in this comparative example has a weight-average molecular weight of 150 kDa, a molecular weight distribution of 2.1, a glass transition temperature of 132℃, a 5 wt% thermal weight loss temperature of 429℃, a refractive index of 1.53, and a light transmittance of 90.3%.

[0052] Comparative Example 2 The main difference between this comparative example and Examples 2 and 4 is that no carbazole-containing cyclic olefin monomer f was added; instead, 1.6 g of tetracyclododecene was used in the ethylene copolymerization. Specifically, a 75 mL glass pressure reactor connected to a gas pipeline was first vacuum-dried at 110 °C for 1 h, and the process was repeated three times with vacuuming and nitrogen purging, followed by three ethylene purgings. The system temperature was then set to 90 °C. Subsequently, under a nitrogen atmosphere, 2.5 mL of a 1 mol / L MAO cocatalyst solution prepared from toluene, 8 mL of toluene, and 1.6 g of tetracyclododecene were added to the reactor. 5.0 μmol of Cat4 was dissolved in 2 mL of toluene and injected into the polymerization system using a syringe. Ethylene was introduced while stirring at 500 rpm and the ethylene pressure was maintained at 1 bar. After 10 min, the pressure reactor was emptied, 200 mL of hydrochloric acid-ethanol was added to quench the polymerization reaction, the polymer was filtered, and dried in a vacuum oven to constant weight, yielding 1.71 g of the cyclic olefin copolymer.

[0053] The comparative example yielded a cyclic olefin copolymer with a weight-average molecular weight of 140 kDa, a molecular weight distribution of 2.1, a glass transition temperature of 169℃, a 5 wt% thermal weight loss temperature of 432℃, a refractive index of 1.54, and a light transmittance of 91.2%.

[0054] Test methods The glass transition temperature of the polymer was determined by differential scanning calorimetry (DSC) using a Mettler TOPEMDSC (Mettler-Toledo, Zurich, Switzerland) DSC at a heating / cooling rate of 10 °C / min. Thermogravimetric analysis (TGA) was performed using a Mettler-Toledo TGA2 instrument. Transmittance was measured using a Shimadzu UV-3600 UV-Vis-NIR spectrophotometer at wavelengths of 400–800 nm. Refractive index was measured using an Abbe refractometer (DR-M4) at 25 °C and a wavelength of 589 nm. The molecular weight and molecular weight distribution index of the polymer were determined using a PL-GPC220 gel permeation chromatography system with trichlorobenzene as the solvent at 150 °C and a flow rate of 1.0 mL / min.

[0055] Test Result Analysis The refractive indices of the carbazole-containing cyclic olefin copolymers obtained in Examples 1-4 were 1.58-1.60, while the refractive indices of the carbazole-free cyclic olefin copolymers obtained in Comparative Examples 1-2 were 1.53-1.54. This demonstrates that introducing carbazole-containing cyclic olefin monomers into the copolymerization system of ethylene and cyclic olefin monomers significantly increases the refractive index of the resulting cyclic olefin terpolymers. The light transmittance of the polymers obtained in Examples 1-4 was 90.1%-91.6%, indicating that the introduction of carbazole-containing cyclic olefin monomers did not significantly impair the transparency of the material, and the resulting materials remain suitable for use in optical materials where light transmittance is required.

[0056] In terms of heat resistance, the glass transition temperatures of the carbazole-containing cyclic olefin copolymers obtained in Examples 1-4 are 162-189°C, and the thermogravimetric temperatures (TGAs) at 5 wt% are 428-436°C. Among them, Examples 2 and 4, which use tetracyclododecene, have glass transition temperatures of 178°C and 189°C, respectively. Combined with Comparative Examples 1 and 2, it can be seen that copolymerizing carbazole-containing cyclic olefin monomers with ethylene, norbornene, or tetracyclododecene can improve the refractive index while maintaining high glass transition temperatures and TGAs.

[0057] The main difference between Comparative Example 1 and Examples 1 and 3 is that no carbazole-containing cyclic olefin monomer was added, and instead, norbornene was copolymerized with ethylene. The refractive index of the polymer obtained in Comparative Example 1 was 1.53, while the refractive index of the polymers obtained in Examples 1 and 3 was 1.58. This difference indicates that the introduction of a carbazole-containing cyclic olefin monomer can increase the refractive index of the norbornene-ethylene copolymer system. The main difference between Comparative Example 2 and Examples 2 and 4 is that no carbazole-containing cyclic olefin monomer was added, and instead, tetracyclododecene was copolymerized with ethylene. The refractive index of the polymer obtained in Comparative Example 2 was 1.54, while the refractive indices of the polymers obtained in Examples 2 and 4 were 1.60 and 1.59, respectively. This difference indicates that the introduction of a carbazole-containing cyclic olefin monomer can increase the refractive index of the tetracyclododecene-ethylene copolymer system.

[0058] The carbazole-functionalized cyclic olefin copolymer provided in this application exhibits significant improvements in both optical and thermal properties. Optically, the copolymer's refractive index reaches 1.58–1.60, significantly higher than the 1.53–1.54 of the carbazole-free control; simultaneously, the visible light transmittance remains above 90%. In terms of thermal stability, the polymer's glass transition temperature is 162–189 °C, and its 5% thermogravimetric temperature is as high as 428–436 °C, indicating excellent thermal stability under high-temperature conditions. The cyclic olefin copolymer prepared in this application possesses high molecular weight (114–159 kDa) and narrow distribution (PDI 2.2–2.3), making it suitable for large-scale industrial production. In summary, this application provides a cyclic olefin copolymer material that combines high refractive index, excellent thermal stability, and high transparency, showing broad application prospects in the optical field.

[0059] The embodiments described above are merely preferred embodiments of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the technical principles of this application, and these improvements and substitutions should also be considered within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the scope of the claims.

Claims

1. A cyclic olefin terpolymer, characterized by, It has the structure of Formula I: In this context, x represents 40% to 70% of the total number of moles of all structural units, y represents 20% to 50% of the total number of moles of all structural units, and z represents 1% to 20% of the total number of moles of all structural units; p is 0 or 1; q is 0 or 1; 20 ≤ n ≤ 5000.

2. The cyclic olefin terpolymer according to claim 1, characterized in that The cyclic olefin terpolymer is any one of the following formulas: 。 3. The cyclic olefin terpolymer according to claim 1, characterized in that The weight-average molecular weight of the cyclic olefin terpolymer is 5~600kDa; the glass transition temperature is 162~189℃; and the 5wt% thermal weight loss temperature is 428~436℃.

4. A method for preparing the cyclic olefin terpolymer according to any one of claims 1-3, characterized in that, include: In an inert solvent, a cyclic olefin monomer, a carbazole-containing cyclic olefin monomer having the structure of formula II, and an ethylene monomer are polymerized in the presence of a catalyst to obtain a cyclic olefin terpolymer having the structure of formula I. Among them, the carbazole-containing cyclic olefin monomers with the structure of Formula II are shown below: Where q is 0 or 1.

5. The method for preparing the cyclic olefin terpolymer according to claim 4, characterized in that, The cyclic olefin monomer is norbornene or tetracyclododecene.

6. The method for preparing the cyclic olefin terpolymer according to claim 4, characterized in that, The carbazole-containing cyclic olefin monomer having the structure of formula II is selected from either formula e or formula f: 。 7. The method for preparing the cyclic olefin terpolymer according to claim 4, characterized in that, The molar ratio of the catalyst to the cyclic olefin monomer is 1:(500~5000). The molar ratio of the catalyst to the carbazole-containing cyclic olefin monomer having the structure of Formula II is 1: (50~2500).

8. The method for preparing the cyclic olefin terpolymer according to claim 4, characterized in that, The catalyst is a metallocene catalyst, which is any one of the following: ethyl-bridged bis(indene) zirconium chloride catalyst, dimethylsilyl-bridged bis(indene) zirconium chloride catalyst, isopropylidene-bridged fluorene zirconium chloride catalyst, diphenylmethylene-bridged fluorene zirconium chloride catalyst, and diphenylmethylene-bridged 2,7-di-tert-butylfluorene zirconium chloride catalyst.

9. The method for preparing the cyclic olefin terpolymer according to claim 4, characterized in that, The polymerization reaction is carried out at a temperature of 30~120℃ for a duration of 5~240 min.

10. The application of a cyclic olefin terpolymer according to any one of claims 1-3, or a cyclic olefin terpolymer prepared by the preparation method according to any one of claims 4-9, in optical materials.

Images