An antioxidant cycloolefin copolymer and a method for preparing the same

Abstract

The application discloses an antioxidant cycloolefin copolymer and a preparation method thereof. The cycloolefin copolymer has the structure shown in the figure, wherein the ethylene unit of the x structure accounts for 50-90% of the total moles of all structural units, the cycloolefin unit of the y structure accounts for 10-45% of the total moles of all structural units, and the cycloolefin monomer containing an antioxidant functional group of the z structure accounts for 0.1-20% of the total moles of all structural units. Compared with a traditional ethylene and cycloolefin binary copolymer, the cycloolefin monomer containing an antioxidant functional group of the application makes the copolymer have thermal oxygen and photo oxygen stability; compared with directly adding an antioxidant in a finished product, the method is simple and easy to implement, and the shortcomings of poor compatibility and poor migration resistance of the antioxidant are avoided.

Description

Technical Field

[0001] This invention belongs to the field of copolymers, and specifically relates to an antioxidant cyclic olefin copolymer and its preparation method. Background Technology

[0002] Ethylene-cyclic olefin copolymers (COCs) are amorphous polymers obtained by copolymerizing ethylene and cyclic olefin monomers using metallocene catalysts in solution polymerization. They are non-crystalline thermoplastic transparent resins widely used in optical lenses, medical applications, packaging, and electronics. Due to their high purity, low protein adsorption, good drug compatibility, high biocompatibility, and resistance to alkaline solutions, they can withstand various sterilization methods, including ultraviolet light. They are used to replace borosilicate glass in novel drugs and therapies, in pre-filled syringes and vials; they can be used to manufacture medical film products such as blister packs, infusion bags, and barrier bags; and they can also be used to manufacture microfluidic chips, PCR plates, and other biological diagnostic instruments. As the market applications of cyclic olefin copolymers continue to expand, the problems associated with their use are becoming increasingly prominent. When used in medical products, the material is often treated with methods such as irradiation sterilization. During irradiation, gamma rays and electron beams can cause the polymer to generate free radicals or chromophores, leading to unavoidable degradation, oxidation, and discoloration.

[0003] To reduce oxidation and discoloration, existing technologies typically add additional antioxidants to cyclic olefin polymers. Japanese Invention Patent JP1994206866A discloses a method for preparing and using a light stabilizer. Compared to other types of light stabilizers, this stabilizer exhibits good compatibility with polymer materials; large-scale blending does not affect the molding properties of the material, and even small-scale blending can provide long-term photostability to polymer materials, making it a continuous light stabilizer.

[0004] However, while added additives do have some inhibitory effect on radiation oxidation, photo-oxidation, and thermal oxidation, these antioxidant and light-stabilizing additives have drawbacks such as poor compatibility with materials, poor migration resistance, and reduced material formability and mechanical properties. They cannot meet the cleanliness and biosafety requirements for medical or packaging materials, and may even cause environmental and biological safety issues due to additive release. Furthermore, they increase the difficulty of material processing and usage costs. Therefore, how to provide a cyclic olefin copolymer with good antioxidant properties, good migration resistance, and easy processing has become one of the hot research topics in the industry. Summary of the Invention

[0005] In view of the above, the present invention provides an antioxidant cyclic olefin copolymer and its preparation method. The polymer is a transparent resin with an amorphous structure at room temperature and has thermal and photo-oxidation stability. Compared with directly adding antioxidants to the finished product, this method is simple and easy to implement, and avoids the disadvantages of poor compatibility and poor migration resistance of antioxidants.

[0006] To achieve the objectives of this invention, the following technical solution is provided:

[0007] An antioxidant cyclic olefin copolymer having the structure shown in formula (I):

[0008]

[0009] In the cyclic olefin copolymer, the molar number x of ethylene units accounts for 50-90% of the total molar number (x+y+z) of all structural units, the molar number y of cyclic olefin units accounts for 9.9-45% of the total molar number of all structural units, and the molar number z of cyclic olefin monomers containing antioxidant functional groups accounts for 0.1-20% of the total molar number of all structural units; in formula (Ⅰ), R1 and R2 are the same or different, preferably hydrogen, phenyl, carboxyl, substituted or unsubstituted alkyl, etc.; R3 and R4 are the same or different, selected from hydrogen, phenyl, carboxyl, substituted or unsubstituted alkyl or antioxidant functional groups, wherein at least one of R3 and R4 is an antioxidant functional group; m is 0-5, preferably 0-2; n is 0-5, preferably 0-2.

[0010] The antioxidant functional group has a -babc structure.

[0011] a structure is selected from -O-, -O-CO-, -CO-O-, -O-CO-O-, -CO-, -CO-NH-, -NH-CO-, -NH-, -S-, -SO2-, -SO-, -O-CS- O-, -O-CO-NH-, -NH-CO-NH-, -O-CS-NH-, -NH-CS-NH-, -NH-C(NH)-NH-, -NH-CO-O- or -NH-CS-O-, etc.;

[0012] Structure b is selected from chemical bonds, C1 to C20 straight-chain or branched alkylene groups, preferably chemical bonds, C1 to C6 straight-chain or branched alkylene groups;

[0013] The c structure is selected from any of the following structures:

[0014] (1) A saturated or unsaturated six-membered (hetero)cyclic substituent, wherein the ring optionally contains one or more identical or different substituents, said substituents being heteroatoms and / or hydroxyl groups and / or straight-chain or branched alkyl or alkoxy groups of C1 to C20;

[0015] (2) An ether substituent containing a saturated or unsaturated six-membered (hetero) ring, wherein the ring optionally contains one or more identical or different heteroatoms and / or hydroxyl groups and / or C1 to C20 straight-chain or branched alkyl or alkoxy groups;

[0016] (3) An amine substituent containing a saturated or unsaturated six-membered (hetero) ring, wherein the ring optionally contains one or more identical or different heteroatoms and / or hydroxyl groups and / or C1-C20 straight-chain or branched alkyl or alkoxy groups;

[0017] The aforementioned heteroatoms include O, N, P, S, etc.

[0018] The c-structure is more preferably the following structure:

[0019]

[0020] S1 and S2 may be the same or different, and are respectively selected from hydrogen atoms, straight-chain or branched alkyl groups of C1 to C20, preferably straight-chain or branched alkyl groups of C1 to C6.

[0021] The weight-average molecular weight of the cyclic olefin copolymer is between 10,000 and 1,000,000, preferably between 30,000 and 600,000.

[0022] The molecular weight distribution of the cyclic olefin copolymer is between 1 and 10, preferably between 1 and 5.

[0023] The glass transition temperature of the cyclic olefin copolymer is 80–300°C, preferably 100–200°C.

[0024] The present invention also provides a method for preparing a cyclic olefin copolymer, comprising the following steps: in the presence of a catalyst system and a solvent, ethylene, a cyclic olefin monomer, and a cyclic olefin monomer containing antioxidant functional groups undergo a polymerization reaction.

[0025] The cyclic olefin monomer is shown in formula (II), wherein R1 and R2 are the same or different, and their meanings are the same as those described above, and n is 0 to 5, preferably 0 to 2.

[0026]

[0027] The cyclic olefin monomer containing antioxidant functional groups is shown in formula (Ⅲ), wherein R 3、 R4 has the same meaning as above; m is 0 to 5, preferably 0 to 2.

[0028]

[0029] The polymerization reaction temperature is 50–200°C, preferably 90–160°C.

[0030] The polymerization reaction time is 0.5 to 120 min, preferably 1 to 30 min.

[0031] As a preferred embodiment, after the polymerization reaction is completed, a hydrochloric acid / ethanol solution is injected into the reaction solution at room temperature and normal pressure, the mixture is stirred to precipitate, filtered to obtain the polymer, and then dried.

[0032] The reaction of cyclic olefin copolymers can be carried out using catalyst systems known in the art.

[0033] As a preferred embodiment, the catalyst system for the polymerization reaction comprises: transition metal complexes, organoboron compounds, and organoaluminum compounds.

[0034] The transition metal complex has the following structure (VI):

[0035]

[0036] In formula (VI), R5 and R6 are each independently selected from unsubstituted cyclopentadienyl and its derivatives, indenyl and its derivatives, or fluorenyl and its derivatives.

[0037] R7 and R8 are independently selected from hydrogen, methyl, ethyl, isopropyl, tert-butyl, phenyl, 2,6-dimethylphenyl, 4-methylphenyl, mestrimethylphenyl, 2,6-diisopropylphenyl, 2,4,6-triisopropylphenyl or 2,6-ditert-butylphenyl;

[0038] X1 and X2 are monoanion ligands, and X1 and X2 are independently selected from hydrogen, straight-chain or branched aliphatic or alicyclic groups containing 1 to 20 carbon atoms, phenyl, straight-chain or branched alkyl or cyclic aliphatic or aromatic groups substituted with 1 to 20 carbon atoms, straight-chain or branched alkoxy groups containing 1 to 20 carbon atoms, straight-chain or branched alkylamine groups containing 1 to 20 carbon atoms, straight-chain or branched aromaticamine groups containing 1 to 20 carbon atoms, straight-chain or branched silyl groups containing 1 to 20 carbon atoms, borohydride, allyl and allyl derivatives or halogens;

[0039] M is selected from transition metal atoms, such as zirconium, titanium, vanadium, chromium, hafnium, etc.

[0040] E is C, Si, or Ge;

[0041] m = 1 or 2;

[0042] The organoboron compound is an ionic compound formed by organoboron anions and cations;

[0043] The organoboron anion is selected from tetraphenylborate, tetra(monofluorophenyl)borate, tetra(difluorophenyl)borate, tetra(trifluorophenyl)borate, tetra(tetrafluorophenyl)borate, tetra(pentafluorophenyl)borate, tetra(tetrafluoromethylphenyl)borate, tetra(tolyl)borate, tetra(xylyl)borate, (triphenyl,pentafluorophenyl)borate, [tri(pentafluorophenyl),phenyl]borate or undecanoyl-7,8-dicarboundecanoate;

[0044] The cation is selected from carbium cations, oxonium cations, ammonium cations, phosphonium cations, cycloheptatrienyl cations, or ferrocene cations containing transition metals;

[0045] The carbium cations include trisubstituted carbium cations such as triphenyl carbium cations and tri(substituted phenyl) carbium cations, and tri(substituted phenyl) carbium cations such as tri(tolyl) carbium cations;

[0046] The ammonium cations include trialkylammonium cations such as trimethylammonium cation, triethylammonium cation, tripropylammonium cation, and tributylammonium cation;

[0047] The phosphonium cation includes triarylphosphonium cations such as triphenylphosphonium cation, tri(tolyl)phosphonium cation or tri(xylyl)phosphonium cation;

[0048] The organoaluminum compounds are selected from hydrocarbon-substituted aluminum compounds, including but not limited to diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, diphenylaluminum hydride, di-p-tolylaluminum hydride, dibenzylaluminum hydride, phenylethylaluminum hydride, phenyl-n-propylaluminum hydride, p-tolylethylaluminum hydride, p-tolyl-n-propylaluminum hydride, p-tolylisopropylaluminum hydride, benzylethylaluminum hydride, benzyl-n-propylaluminum hydride, benzylisopropylaluminum hydride, ethylaluminum dihydride, butylaluminum dihydride, isobutylaluminum dihydride, octylaluminum dihydride, and pentylaluminum dihydride. One or more of the following: diethylaluminum ethoxide, dipropylaluminum ethoxide, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum, triphenylaluminum, tri-p-tolylaluminum, tribenzylaluminum, ethyl diphenylaluminum, ethyl di-p-tolylaluminum, ethyl dibenzylaluminum, diethylphenylaluminum, diethyl p-tolylaluminum, and diethylbenzylaluminum; preferably, the organoaluminum compound is one or more of diisobutylaluminum hydride, diethylaluminum hydride, trioctylaluminum, triisobutylaluminum, and trimethylaluminum.

[0049] The pressure of ethylene in the polymerization reaction system is 1 to 12 atm, preferably 1 to 10 atm.

[0050] The concentration of the transition metal complex in the polymerization solution system is 0.1–5 μmol / ml, preferably 0.2–2 μmol / ml.

[0051] The organoboron compound and organoaluminum compound serve as co-catalysts, and the molar ratio of the organoboron compound to the transition metal complex is (1-10000):1, preferably (1-100):1.

[0052] The molar ratio of the organoaluminum compound to the transition metal complex is (1~).

[0053] 10000): 1, preferred (1~100): 1.

[0054] The solvent for the polymerization reaction is selected from one or more of aliphatic saturated hydrocarbons, aromatic hydrocarbons, aryl halides and cycloalkanes; preferably at least one of pentane, hexane, toluene, xylene, heptane, cyclohexane, cycloheptane, dichloromethane, chlorobenzene, o-dichlorobenzene and dichloroethane, and more preferably at least one of toluene, hexane and cyclohexane.

[0055] Compared with existing technologies, this invention provides an antioxidant cyclic olefin copolymer and its preparation method. The cyclic olefin copolymer provided by this invention contains antioxidant functional groups and exhibits resistance to thermal oxidation and photo-oxidation. Furthermore, by controlling the ratio of the three comonomers, the glass transition temperature of the polymer can be controlled within a range of 80℃ to 200℃. Compared with traditional ethylene-cyclic olefin binary copolymers, this preparation method results in materials with better antioxidant properties. The method is simple and easy to implement, saving production costs. Therefore, this polymer has great application prospects in packaging materials, medical materials, and other fields. Detailed Implementation

[0056] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0057] Test method:

[0058] 1. The composition of each monomer of the cyclic olefin copolymer was determined by hydrogen nuclear magnetic resonance (HMR) and carbon nuclear magnetic resonance (CMR) spectroscopy using a Varian Inova-400 (FT, 400MHz, 1H; 100MHz, 13C) instrument.

[0059] 2. Weight-average molecular weight (Mw) and molecular weight distribution (PDI) were determined by high-temperature gel permeation chromatography. 1,2,4-trichlorobenzene was used as the mobile sample, and narrow-distribution polystyrene was used as the standard sample. The temperature was 150℃.

[0060] 3. The glass transition temperature (Tg) was determined by DSC at a heating rate of 10℃ / min and a temperature range of 25~400℃.

[0061] 4. Gamma-ray irradiation and testing: The film samples were irradiated in air at room temperature with a total gamma-ray dose of 25 kGy. The irradiated samples were then subjected to Soxhlet extraction with toluene solution for 24 hours, followed by molecular weight testing and gel content determination. The content of antioxidant additives in the copolymer was determined using a dissolution / precipitation method on the irradiated film samples.

[0062] 5. The source information of the raw materials used in the following examples is as follows. Unless otherwise specified, all other raw materials are conventional in the art, and the purity specifications used are analytical grade or chemically pure:

[0063]

[0064]

[0065]

[0066] 6. The preferred structure of the main catalyst is as follows:

[0067] Example 1

[0068] Catalyst preparation: Weigh out 10 μmol of the main catalyst Cat1 and Al in a glove box. i Bu3 (20 μmol) and triphenylcarbon tetra(pentafluorophenyl)borate [Ph3C][B(C6F5)4] (10 μmol) were dissolved in 5 mL of toluene to obtain a catalyst solution.

[0069] Synthesis of cyclic olefin monomers containing antioxidant functional groups:

[0070]

[0071] 1.15 mol of compound 1a and 1.15 mol of cyclopentadiene 1b were added to a 500 ml stainless steel reactor and reacted at 200 °C for 2 hours to obtain a reaction solution containing the compound shown in 1c above. This solution was then distilled, concentrated, and purified to obtain the cyclic olefin monomer 1c. The NMR results are as follows: 1 H-NMR (400MHz, CDCl3): δ=1.33(18H); δ=1.30-1.77(4H); δ=2.04-2.60(3H); δ=3.77-4.03(2H); δ=5.35(1H); δ=6.22(2H); δ=6.87(2H).

[0072] Synthesis of cyclic olefin copolymers:

[0073] Before the experiment, the reactor was preheated to 100℃, and the vacuuming and nitrogen purging process was repeated three times. After the process, the reactor was cooled to room temperature. 20 mmol (0.5 mol / L) of toluene solution containing 1c monomer, 20 mmol of monomer 2-norbornene (NB, n=0, R1, R2 are hydrogen), and 20 mL of toluene were added to a 150 mL reactor, followed by thorough purging with nitrogen. The reactor temperature was then raised to 140℃, and stirring was started. Under vigorous stirring, 1.0 atm of ethylene was introduced to saturate the toluene solution. After the pressure stabilized, the catalyst solution was injected through the reactor's feed hopper, followed by the introduction of 8.0 atm of ethylene for the reaction. After 15 minutes of reaction, the heating was stopped, the pressure was released, and the reactor was opened. Ethanol solution was injected to terminate the reaction and inactivate the polymer. A large amount of ethanol solution was then added for precipitation, and the polymer precipitated in the ethanol. The polymer was removed from the ethanol and placed in a vacuum dryer until constant weight was obtained to obtain the cyclic olefin copolymer. The polymer Mw was 15.39 × 10⁻⁶. 4 The polymer was heated to a concentration of g / mol, with a PDI of 2.8, a Tg of 162℃, an ethylene insertion rate of 64.5 mol%, a 2-norbornene monomer insertion rate of 34.6 mol%, and a 1c monomer insertion rate of 0.9 mol%. The polymer was hot-pressed into a film and tested with a 25 kGy radiation dose. After the test, Mw and PDI remained almost unchanged, and the gel content was 0%.

[0074] Example 2

[0075] Catalyst preparation: Weigh the main catalyst Cat1 (10 μmol), AlEt3 (20 μmol) and triphenylcarbon tetra(pentafluorophenyl)borate [Ph3C][B(C6F5)4] (10 μmol) in a glove box and dissolve them in 5 mL of toluene to obtain the catalyst solution.

[0076] Synthesis of cyclic olefin monomers containing antioxidant functional groups:

[0077]

[0078] 1.15 mol of 2a and 1.15 mol of cyclopentadiene 2b were added to a 500 ml stainless steel reactor and reacted at 200 °C for 2 hours to obtain a reaction solution containing the compound shown in 2c above. This solution was then distilled, concentrated, and purified to obtain the cycloolefin monomer 2c. The NMR results are as follows: 1 H-NMR (400MHz, CDCl3): δ=1.34-1.77(4H); δ=1.84(1H); δ=2.15(6H); δ=2.30-2. 60(2H); δ=3.20-3.45(2H); δ=4.66(2H); δ=5.37(1H); δ=6.20(2H); δ=6.88(2H).

[0079] Synthesis of cyclic olefin copolymers:

[0080] Before the experiment, the reactor was preheated to 100℃, and the vacuuming and nitrogen purging process was repeated three times. After the process, the reactor was cooled to room temperature. 20 mmol (0.5 mol / L) of toluene solution containing 2c monomer, 20 mmol of tetracyclododecene monomer (TCD, n=1, R1 and R2 are hydrogen), and 20 mL of toluene were added to a 150 mL reactor, followed by thorough purging with nitrogen. The reactor temperature was then raised to 130℃, and stirring was started. Under vigorous stirring, 1.0 atm of ethylene was introduced to saturate the toluene solution. After the pressure stabilized, the catalyst solution was injected through the reactor's feed hopper, followed by the introduction of 8.0 atm of ethylene for the reaction. After 12 minutes of reaction, heating was stopped, the reactor was opened, and ethanol solution was injected to terminate the reaction and inactivate the polymer. A large amount of ethanol solution was then added for precipitation, and the polymer precipitated in the ethanol. The polymer was removed from the ethanol and placed in a vacuum dryer until constant weight was obtained, yielding a cyclic olefin copolymer with a polymer Mw of 12.54 × 10⁻⁶. 4 The polymer was heated to form a film, and tested with a radiation dose of 25 kGy. The Mw and PDI were almost unchanged after the test, and the gel content was 0%. The PDI was 2.9 g / mol, the Tg was 174℃, the ethylene insertion rate was 61.6 mol%, the tetracyclododecene insertion rate was 36.2 mol%, and the 2c monomer insertion rate was 2.2 mol%.

[0081] Example 3

[0082] Catalyst preparation: Weigh the main catalyst Cat2 (10 μmol), AlMe3 (20 μmol) and triphenylcarbon tetra(pentafluorophenyl)borate [Ph3C][B(C6F5)4] (10 μmol) in a glove box and dissolve them in 5 mL of toluene to obtain the catalyst solution.

[0083] Synthesis of cyclic olefin monomers containing antioxidant functional groups:

[0084]

[0085] 1.15 mol of 3a and 1.15 mol of dicyclopentadiene 3b were added to a 500 ml stainless steel reactor and reacted at 200 °C for 2 hours to obtain a reaction solution containing the compound shown in 3c above. This solution was then distilled, concentrated, and purified to obtain the cyclic olefin monomer 3c. The NMR results are as follows: 1H-NMR (400MHz, CDCl3): δ=0.69-0.94(2H); δ=1.36(18H); δ=1.42-1.48(3H); δ=1.51-1 .75(2H); δ=1.87-2.13(3H); δ=2.26-2.58(3H); δ=5.33(1H); δ=6.05(2H); δ=7.17(2H).

[0086] Synthesis of cyclic olefin copolymers:

[0087] Before the experiment, the reactor was preheated to 100℃, and the vacuuming and nitrogen purging process was repeated three times. After the process, the reactor was cooled to room temperature. 20 mmol (0.5 mol / L) of toluene solution containing 3c monomer, 20 mmol of monomer 2-norbornene (n = 0, R1 and R2 are hydrogen), and 20 mL of toluene were added to a 150 mL reactor, followed by thorough purging with nitrogen. The reactor temperature was then raised to 120℃, and stirring was started. Under vigorous stirring, 1.0 atm of ethylene was introduced to saturate the toluene solution. After the pressure stabilized, the catalyst solution was injected through the reactor's feed hopper, followed by the introduction of 9.0 atm of ethylene to initiate the reaction. After 10 minutes of reaction, heating was stopped, the reactor was opened, and ethanol solution was injected to terminate the reaction and inactivate the polymer. A large amount of ethanol solution was then added for precipitation, and the polymer precipitated in the ethanol. The polymer was removed from the ethanol and dried in a vacuum dryer until constant weight was obtained, yielding a cyclic olefin copolymer with a polymer Mw of 11.77 × 10⁻⁶. 4 The polymer was heated to a concentration of g / mol, with a PDI of 2.9, a Tg of 167℃, an ethylene insertion rate of 63.4 mol%, a 2-norbornene insertion rate of 35.3 mol%, and a 3C monomer insertion rate of 1.3 mol%. The polymer was hot-pressed into a film and tested with a 25 kGy radiation dose. After the test, Mw and PDI remained almost unchanged, and the gel content was 0%.

[0088] Example 4

[0089] Catalyst preparation: Weigh out 10 μmol of the main catalyst Cat2 and Al in a glove box. i Bu3 (20 μmol) and triphenylcarbon tetra(pentafluorophenyl)borate [Ph3C][B(C6F5)4] (10 μmol) were dissolved in 5 mL of toluene to obtain a catalyst solution.

[0090] Synthesis of cyclic olefin monomers containing antioxidant functional groups:

[0091]

[0092] 1.15 mol of 4a and 1.15 mol of dicyclopentadiene 4b were added to a 500 ml stainless steel reactor and reacted at 200 °C for 2 hours to obtain a reaction solution containing the compound shown in 4c above. This solution was then distilled, concentrated, and purified to obtain the cyclic olefin monomer 4c. The NMR results are as follows: 1 H-NMR (400MHz, CDCl3): δ=0.68-0.92(2H); δ=1.35(18H); δ=1.22-1.49(6H); δ=1.68 (1H); δ=1.87-2.11(2H); δ=2.57-2.88(4H); δ=5.35(1H); δ=6.06(2H); δ=7.25(2H).

[0093] Synthesis of cyclic olefin copolymers:

[0094] Before the experiment, the reaction vessel was preheated to 100°C, and the vacuuming and nitrogen purging process was repeated three times. After the process, the reaction vessel was cooled to room temperature. 20 mmol (0.5 mol / L) of toluene solution containing 4C monomer and 20 mmol of monomer 5,6-dimethyl-2-norbornene were added to a 150 ml reaction vessel. 20 mL of toluene was added and thoroughly purged with nitrogen. The reactor temperature was then raised to 140°C, and stirring was initiated. Under vigorous stirring, 1.0 atm of ethylene was introduced to saturate the toluene solution. After pressure stabilization, a catalyst solution was injected through the reactor's feed hopper, followed by the introduction of 9.0 atm of ethylene for further reaction. After 30 minutes of reaction, heating was stopped, the reactor was opened, and ethanol solution was injected to terminate the reaction and inactivate the polymer. A large amount of ethanol solution was then added for precipitation, resulting in polymer precipitation in the ethanol. The polymer was removed from the ethanol and dried in a vacuum dryer until constant weight was obtained, yielding a cyclic olefin copolymer with a polymer Mw of 13.69 × 10⁻⁶. 4 The polymer was heated to a concentration of g / mol, with a PDI of 3.0, a Tg of 161℃, an ethylene insertion rate of 62.7 mol%, a 5,6-dimethyl-2-norbornene insertion rate of 34.5 mol%, and a 4c monomer insertion rate of 2.8 mol%. The polymer was hot-pressed into a film and tested with a 25 kGy radiation dose. After the test, Mw and PDI remained almost unchanged, and the gel content was 0%.

[0095] Example 5

[0096] Catalyst preparation: Weigh the main catalyst Cat3 (10 μmol), AlMe3 (20 μmol) and triphenylcarbon tetra(pentafluorophenyl)borate [Ph3C][B(C6F5)4] (10 μmol) in a glove box and dissolve them in 5 mL of toluene to obtain the catalyst solution.

[0097] Synthesis of cyclic olefin monomers containing antioxidant functional groups:

[0098]

[0099] 5a (29 mmol), metallic sodium (29 mmol), and butanol (80 mL) were added to a reactor, and the reaction was refluxed at 85 °C for 8 hours. After cooling, the liquid was concentrated to 20 mL. Anhydrous DMF (85 mL) and bromide 5b (145 mmol) were added to the liquid, and the mixture was heated at 50 °C for 2 hours until the pH reached neutral. The concentrate was obtained by vacuum rotary evaporation at 100 °C. The concentrate was dissolved in benzene (100 mL) and washed successively with distilled water, sodium hydroxide solution, and distilled water. The organic matter obtained by extraction was dried with MgSO4 and filtered to obtain a transparent yellow oily intermediate. The intermediate (1.15 mol) and cyclopentadiene (1.15 mol) were added to a 500 mL stainless steel reactor, and the reaction was carried out at 200 °C for 2 hours to obtain a reaction solution containing the compound shown in 5c above. The solution was distilled, concentrated, and purified to obtain the cyclic olefin monomer 5c. The NMR results are as follows: 1 H-NMR (400MHz, CDCl3): δ=1.46-1.88(4H); δ=2.22(1H); δ=2.43(1H); δ=3.35(6H); δ=3.42(1H); δ=4.30(2H); δ=6.23(2H).

[0100] Synthesis of cyclic olefin copolymers:

[0101] Before the experiment, the reaction vessel was preheated to 100°C, and the vacuuming and nitrogen purging process was repeated three times. After the process, the reaction vessel was cooled to room temperature. 20 mmol (0.5 mol / L) of toluene solution containing 5C monomer and 20 mmol of methyltetracyclododecene monomer were added to a 150 ml reaction vessel. 20 mL of toluene was added and thoroughly purged with nitrogen. The reactor temperature was then raised to 160°C, and stirring was initiated. Under vigorous stirring, 1.0 atm of ethylene was introduced to saturate the toluene solution. After pressure stabilization, a catalyst solution was injected through the reactor's feed hopper, followed by the introduction of 9.0 atm of ethylene for further reaction. After 12 minutes of reaction, heating was stopped, the reactor was opened, and ethanol solution was injected to terminate the reaction and inactivate the polymer. A large amount of ethanol solution was then added for precipitation, resulting in polymer precipitation in the ethanol. The polymer was removed from the ethanol and dried in a vacuum dryer until constant weight was obtained, yielding a cyclic olefin copolymer with a polymer Mw of 9.07 × 10⁻⁶. 4The polymer was heated to a concentration of g / mol, with a PDI of 2.7, a Tg of 175℃, an ethylene insertion rate of 62.0 mol%, a methyltetracyclododecene insertion rate of 36.3 mol%, and a 5c monomer insertion rate of 1.7 mol%. The polymer was hot-pressed into a film and tested with a 25 kGy radiation dose. After the test, Mw and PDI remained almost unchanged, and the gel content was 0%.

[0102] Example 6

[0103] Catalyst preparation: Weigh out 10 μmol of the main catalyst Cat3 and Al in a glove box. i Bu3 (20 μmol) and triphenylcarbon tetra(pentafluorophenyl)borate [Ph3C][B(C6F5)4] (10 μmol) were dissolved in 5 mL of toluene to obtain a catalyst solution.

[0104] Synthesis of cyclic olefin monomers containing antioxidant functional groups:

[0105]

[0106] 6a (29 mmol), metallic sodium (29 mmol), and butanol (80 mL) were added to a reactor and refluxed at 85 °C for 8 hours. After cooling, the liquid was concentrated to 20 mL. Anhydrous DMF (85 mL) and bromide 6b (145 mmol) were added to the liquid, and the mixture was heated at 50 °C for 2 hours until the pH reached neutral. The concentrate was obtained by vacuum rotary evaporation at 100 °C. The concentrate was dissolved in benzene (100 mL) and washed successively with distilled water, sodium hydroxide solution, and distilled water. The organic matter obtained by extraction was dried with MgSO4 and filtered to obtain a transparent yellow oily intermediate. The intermediate (1.15 mol) and cyclopentadiene (1.15 mol) were added to a 500 mL stainless steel reactor and reacted at 200 °C for 2 hours to obtain a reaction solution containing the compound shown in 6c above. The solution was distilled, concentrated, and purified to obtain the cyclic olefin monomer 6c. The NMR results are as follows: 1 H-NMR (400MHz, CDCl3): δ=1.34-1.80(4H); δ=2.16(1H); δ=2.29(1H); δ=2.58(1H); δ=2.99-3.25(2H); δ=3.30(6H); δ=5.98(1H); δ=6.06(2H).

[0107] Synthesis of cyclic olefin copolymers:

[0108] Before the experiment, the reaction vessel was preheated to 100°C, and the vacuuming and nitrogen purging process was repeated three times. After the process, the reaction vessel was cooled to room temperature. 20 mmol (0.5 mol / L) of 6C monomer toluene solution and 20 mmol of monomer methyltetracyclododecene were added to a 150 ml reaction vessel. 20 mL of toluene was added and thoroughly purged with nitrogen. The reactor temperature was then raised to 140°C, and stirring was initiated. Under vigorous stirring, 1.0 atm of ethylene was introduced to saturate the toluene solution. After pressure stabilization, a catalyst solution was injected through the reactor's feed hopper, followed by the introduction of 6.0 atm of ethylene for further reaction. After 10 minutes of reaction, heating was stopped, the reactor was opened, and ethanol solution was injected to terminate the reaction and inactivate the polymer. A large amount of ethanol solution was then added for precipitation, resulting in polymer precipitation in the ethanol. The polymer was removed from the ethanol and dried in a vacuum dryer until constant weight was obtained, yielding a cyclic olefin copolymer with a polymer Mw of 10.48 × 10⁻⁶. 4 The polymer was heated to form a film, and tested with a radiation dose of 25 kGy. The Mw and PDI were almost unchanged after the test, and the gel content was 0%. The PDI was 3.1 g / mol, the Tg was 190℃, the ethylene insertion rate was 58.5 mol%, the methyltetracyclododecene insertion rate was 38.3 mol%, and the 6c monomer insertion rate was 3.2 mol%.

[0109] Example 7

[0110] Catalyst preparation: Weigh the main catalyst Cat4 (10 μmol), AlEt3 (20 μmol) and triphenylcarbon tetra(pentafluorophenyl)borate [Ph3C][B(C6F5)4] (10 μmol) in a glove box and dissolve them in 5 mL of toluene to obtain the catalyst solution.

[0111] Synthesis of cyclic olefin monomers containing antioxidant functional groups:

[0112]

[0113] 7a (6 mmol), methanol (20 mmol), lithium methoxy (18 mmol), and tetrahydrofuran (100 mL) were added to a reactor and reacted at -78 °C for 2 days. The temperature was then restored to 25 °C. After filtration and rotary evaporation, the product was dissolved in petroleum ether and separated by column chromatography. The solvent was removed by rotary evaporation to obtain a yellow 7b. 7b (2 mmol) and 5b (2 mmol) were added to the reactor and refluxed at 150 °C for 4 hours. After distillation and purification, a transparent yellow oily intermediate was obtained. The intermediate (1 mol) and cyclopentadiene (1 mol) were added to a 500 mL stainless steel reactor and reacted at 200 °C for 2 hours to obtain a reaction solution containing the compound shown in 7c above. This solution was then distilled, concentrated, and purified to obtain the cyclic olefin monomer 7c. The NMR results are as follows: 1H-NMR (400MHz, CDCl3): δ=0.92(9H); δ=1.59(3H); δ=1.49-1.86(4H); δ=2. 28(1H); δ=2.42(1H); δ=3.40(1H); δ=3.50(6H); δ=4.75(2H); δ=6.09(2H).

[0114] Synthesis of cyclic olefin copolymers:

[0115] Before the experiment, the reaction vessel was preheated to 100°C, and the vacuuming and nitrogen purging process was repeated three times. After the process, the reaction vessel was cooled to room temperature. 20 mmol (0.5 mol / L) of 7c monomer toluene solution and 20 mmol of monomer 5,6-dimethyl-2-norbornene were added to a 150 ml reaction vessel. 20 mL of toluene was added and thoroughly purged with nitrogen. The reactor temperature was then raised to 100°C, and stirring was initiated. Under vigorous stirring, 1.0 atm of ethylene was introduced to saturate the toluene solution. After pressure stabilization, a catalyst solution was injected through the reactor's feed hopper, followed by the introduction of 8.0 atm of ethylene for reaction. After 15 minutes of reaction, heating was stopped, the reactor was opened, and ethanol solution was injected to terminate the reaction and inactivate the polymer. A large amount of ethanol solution was then added for precipitation, resulting in polymer precipitation in the ethanol. The polymer was removed from the ethanol and dried in a vacuum dryer until constant weight was obtained, yielding a cyclic olefin copolymer with a polymer Mw of 14.94 × 10⁻⁶. 4 The polymer was measured at g / mol, with a PDI of 2.8, a Tg of 183℃, an ethylene insertion rate of 60.0 mol%, a 5,6-dimethyl-2-norbornene insertion rate of 37.4 mol%, and a 7c monomer insertion rate of 2.6 mol%. The polymer was hot-pressed into a film and tested with a 25 kGy radiation dose. After the test, Mw and PDI remained almost unchanged, and the gel content was 0%.

[0116] Example 8

[0117] Catalyst preparation: Weigh the main catalyst Cat4 (10 μmol), AlMe3 (20 μmol) and triphenylcarbon tetra(pentafluorophenyl)borate [Ph3C][B(C6F5)4] (10 μmol) in a glove box and dissolve them in 5 mL of toluene to obtain the catalyst solution.

[0118] Synthesis of cyclic olefin monomers containing antioxidant functional groups:

[0119]

[0120] Sodium (6 mmol), methanol (6 mmol), and tetrahydrofuran (70 mL) were added to a reactor and refluxed at 50 °C for 15 hours. After cooling to 0 °C, 8a (2 mmol) was slowly added dropwise to the above solution, and the mixture was refluxed at 50 °C for 12 hours. After filtration and rotary evaporation, the solution was dissolved in petroleum ether and separated by column chromatography. After removing the solvent by rotary evaporation, a pale yellow 8b was obtained. 8b (2 mmol) and 5b (2 mmol) were added to a reactor and refluxed at 150 °C for 4 hours. After distillation and purification, a transparent yellow oily intermediate was obtained. The intermediate (1 mol) and cyclopentadiene (1 mol) were added to a 500 mL stainless steel reactor and reacted at 200 °C for 2 hours to obtain a reaction solution containing the compound shown in 8c above. After distillation, concentration, and purification, the cyclic olefin monomer 8c was obtained. The NMR results are as follows: 1 H-NMR (400MHz, CDCl3): δ=1.02(9H); δ=1.50-1.88(4H); δ=2.27(1H); δ=2. 40(1H); δ=2.69(6H); δ=3.36(1H); δ=3.51(6H); δ=4.69(2H); δ=6.05(2H).

[0121] Synthesis of cyclic olefin copolymers:

[0122] Before the experiment, the reaction vessel was preheated to 100°C, and the vacuuming and nitrogen purging process was repeated three times. After the process, the reaction vessel was cooled to room temperature. 20 mmol (0.5 mol / L) of toluene solution containing 8C monomer and 20 mmol of monomer 5-phenyl-2-norbornene were added to a 150 ml reaction vessel. 20 mL of toluene was added and thoroughly purged with nitrogen. The reactor temperature was then raised to 120°C, and stirring was initiated. Under vigorous stirring, 1.0 atm of ethylene was introduced to saturate the toluene solution. After the pressure stabilized, a catalyst solution was injected through the reactor's feed hopper, followed by the introduction of 10.0 atm of ethylene to initiate the reaction. After 10 minutes of reaction, heating was stopped, the reactor was opened, and ethanol solution was injected to terminate the reaction and inactivate the polymer. A large amount of ethanol solution was then added for precipitation, resulting in polymer precipitation in the ethanol. The polymer was removed from the ethanol and dried in a vacuum dryer until constant weight was obtained, yielding a cyclic olefin copolymer with a polymer Mw of 11.87 × 10⁻⁶. 4 The polymer was heated to a concentration of g / mol, with a PDI of 3.0, a Tg of 177℃, an ethylene insertion rate of 58.7 mol%, a 5-phenyl-2-norbornene insertion rate of 36.6 mol%, and an 8c monomer insertion rate of 4.7 mol%. The polymer was then hot-pressed into a film and tested under a 25 kGy radiation dose. After the test, Mw and PDI remained almost unchanged, and the gel content was 0%.

[0123] Comparative Example 1

[0124] Catalyst preparation: Weigh out 10 μmol of the main catalyst Cat1 and Al in a glove box. i Bu3 (20 μmol) and triphenylcarbon tetra(pentafluorophenyl)borate [Ph3C][B(C6F5)4] (10 μmol) were dissolved in 5 mL of toluene to obtain a catalyst solution.

[0125] Synthesis of cyclic olefin copolymers without antioxidant cyclic olefin monomers:

[0126] Before the experiment, the reactor was preheated to 100℃, and the vacuuming and nitrogen purging process was repeated three times. After the process, the reactor was cooled to room temperature. 40 mmol of 2-norbornene and 20 mL of toluene were added to a 150 mL reactor, and the reactor was thoroughly purged with nitrogen. The reactor temperature was then raised to 140℃, and stirring was started. Under vigorous stirring, 1.0 atm of ethylene was introduced to saturate the toluene solution. After the pressure stabilized, the catalyst solution was injected through the reactor's feed hopper, followed by the introduction of 8.0 atm of ethylene to initiate the reaction. After 15 minutes of reaction, the heating was stopped, the reactor was opened, and ethanol solution was injected to terminate the reaction and inactivate the polymer. A large amount of ethanol solution was then added to induce precipitation, and the polymer precipitated in the ethanol. The polymer was removed from the ethanol and dried in a vacuum dryer until constant weight was obtained, yielding a cyclic olefin copolymer with a polymer Mw of 12.07 × 10⁻⁶. 4 The polymer was heated to form a film with a molecular weight of g / mol, a PDI of 2.9, a Tg of 180℃, an ethylene insertion rate of 63.0 mol%, and a 2-norbornene insertion rate of 37.0 mol%. The polymer was then heated to form a film and tested with a radiation dose of 25 kGy. After the test, the molecular weight increased, the PDI widened, the gel content was 17.2%, and low molecular weight compounds appeared.

[0127] Comparative Example 2

[0128] Catalyst preparation: Weigh out 10 μmol of the main catalyst Cat1 and Al in a glove box. i Bu3 (20 μmol) and triphenylcarbon tetra(pentafluorophenyl)borate [Ph3C][B(C6F5)4] (10 μmol) were dissolved in 5 mL of toluene to obtain a catalyst solution.

[0129] Synthesis of cyclic olefin copolymers without antioxidant cyclic olefin monomers:

[0130] Before the experiment, the reactor was preheated to 100℃, and the vacuuming and nitrogen purging process was repeated three times. After the process, the reactor was cooled to room temperature. 40 mmol of 2-norbornene and 20 mL of toluene were added to a 150 mL reactor, and the mixture was thoroughly purged with nitrogen. The reactor temperature was then raised to 120℃, and stirring was started. Under vigorous stirring, 1.0 atm of ethylene was introduced to saturate the toluene solution. After the pressure stabilized, the catalyst solution was injected through the reactor's feed hopper, followed by the introduction of 9.0 atm of ethylene to initiate the reaction. After 10 minutes of reaction, the heating was stopped, the reactor was opened, and ethanol solution was injected to terminate the reaction and inactivate the polymer. A large amount of ethanol solution was then added to induce precipitation, and the polymer precipitated in the ethanol. The polymer was removed from the ethanol and dried in a vacuum dryer until constant weight was obtained, yielding a cyclic olefin copolymer with a polymer Mw of 11.29 × 10⁻⁶. 4 The polymer was prepared with g / mol, PDI of 3.2, Tg of 176℃, ethylene insertion rate of 67.7 mol%, and 2-norbornene insertion rate of 32.3 mol%. The polymer was blended with 0.5% antioxidant 770 (CAS No.: 52829-07-9) and then hot-pressed into a film. The film was tested with a radiation dose of 25 kGy. After the test, Mw decreased, PDI widened, gel content was 0%, and antioxidant content decreased.

[0131] Comparative Example 3

[0132] Catalyst preparation: Weigh out 10 μmol of the main catalyst Cat1 and Al in a glove box. i Bu3 (20 μmol) and triphenylcarbon tetra(pentafluorophenyl)borate [Ph3C][B(C6F5)4] (10 μmol) were dissolved in 5 mL of toluene to obtain a catalyst solution.

[0133] Synthesis of cyclic olefin copolymers without antioxidant cyclic olefin monomers:

[0134] Before the experiment, the reactor was preheated to 100℃, and the vacuuming and nitrogen purging process was repeated three times. After the process, the reactor was cooled to room temperature. 40 mmol of 2-norbornene and 20 mL of toluene were added to a 150 mL reactor, and the reactor was thoroughly purged with nitrogen. The reactor temperature was then raised to 120℃, and stirring was started. Under vigorous stirring, 1.0 atm of ethylene was introduced to saturate the toluene solution. After the pressure stabilized, the catalyst solution was injected through the reactor's feed hopper, followed by the introduction of 9.0 atm of ethylene to initiate the reaction. After 10 minutes of reaction, the heating was stopped, the reactor was opened, and ethanol solution was injected to terminate the reaction and inactivate the polymer. A large amount of ethanol solution was then added to induce precipitation, and the polymer precipitated in the ethanol. The polymer was removed from the ethanol and dried in a vacuum dryer until constant weight was obtained, yielding a cyclic olefin copolymer with a polymer Mw of 13.26 × 10⁻⁶. 4The polymer was prepared with g / mol, PDI of 2.8, Tg of 169℃, ethylene insertion rate of 68.2 mol%, and 2-norbornene insertion rate of 31.8 mol%. The polymer was blended with 0.5% antioxidant 1010 (CAS No.: 6683-19-8) and then hot-pressed into a film. The film was tested with a radiation dose of 25 kGy. After the test, Mw decreased, PDI widened, gel content was 0%, and antioxidant content decreased.

[0135] Table 1. Detection results of copolymers prepared in the embodiments and comparative examples of the present invention.

[0136]

[0137] Analysis of the comparative examples and implementation data shows that the antioxidant cyclic olefin copolymer proposed in this invention exhibits excellent antioxidant effects. Comparing Examples 1-8 with Comparative Examples 1-3, it was found that the antioxidant cyclic olefin copolymer prepared in this invention maintained its molecular weight after γ-ray irradiation, with no cross-linked polymers formed. In contrast, the cyclic olefin copolymer in Comparative Example 1 without added additives showed an increase in molecular weight after γ-ray irradiation, exhibiting gelation and the appearance of degraded small molecule compounds. Furthermore, the polymers in Comparative Example 2 with added antioxidant 770 or Comparative Example 3 with added antioxidant 1010, due to the small molecular weight of the additives and their easy migration, degraded and decreased in molecular weight after γ-ray irradiation. Therefore, the insertion of antioxidant cyclic olefin monomers into the copolymer of this invention can effectively block polymer oxidation and inhibit the oxidative degradation of molecular chains under γ-ray irradiation, meeting the requirements of antioxidant properties and additive-free (no additive precipitation) in the medical materials field.

Claims

1. An antioxidant cycloolefin copolymer characterized by, It has the structure shown in equation (Ⅰ): In the cyclic olefin copolymer, the molar number x of ethylene units accounts for 50-90% of the total molar number (x+y+z) of all structural units, the molar number y of cyclic olefin units accounts for 9.9-45% of the total molar number of all structural units, and the molar number z of cyclic olefin monomers containing antioxidant functional groups accounts for 0.1-20% of the total molar number of all structural units; in formula (Ⅰ), R1 and R2 may be the same or different, preferably hydrogen, phenyl, carboxyl, substituted or unsubstituted alkyl, etc.; R3 and R4 may be the same or different, selected from hydrogen, phenyl, carboxyl, substituted or unsubstituted alkyl or antioxidant functional groups, wherein at least one of R3 and R4 is an antioxidant functional group; m is 0-5, preferably 0-2; n is 0-5, preferably 0-2; The antioxidant functional group has a -babc structure. a structure is selected from -O-, -O-CO-, -CO-O-, -O-CO-O-, -CO-, -CO-NH-, -NH-CO-, -NH-, -S-, -SO2-, -SO-, -O-CS- O-, -O-CO-NH-, -NH-CO-NH-, -O-CS-NH-, -NH-CS-NH-, -NH-C(NH)-NH-, -NH-CO-O-, or -NH-CS-O-; Structure b is selected from chemical bonds, C1 to C20 straight-chain or branched alkylene groups, preferably chemical bonds, C1 to C6 straight-chain or branched alkylene groups; The c structure is selected from any of the following structures: (1) A saturated or unsaturated six-membered (hetero)cyclic substituent, wherein the ring optionally contains one or more identical or different substituents, said substituents being heteroatoms and / or hydroxyl groups and / or straight-chain or branched alkyl or alkoxy groups of C1 to C20; (2) An ether substituent containing a saturated or unsaturated six-membered (hetero) ring, wherein the ring optionally contains one or more identical or different heteroatoms and / or hydroxyl groups and / or C1 to C20 straight-chain or branched alkyl or alkoxy groups; (3) An amine substituent containing a saturated or unsaturated six-membered (hetero) ring, wherein the ring optionally contains one or more identical or different heteroatoms and / or hydroxyl groups and / or C1-C20 straight-chain or branched alkyl or alkoxy groups; The heteroatoms include O, N, P, and S; The c-structure is more preferably the following structure: wherein S1, S2 are the same or different, each independently selected from the group consisting of a hydrogen atom, a C1-C20 linear or branched alkyl group, preferably a C1-C6 linear or branched alkyl group.

2. The cyclic olefin copolymer according to claim 1, characterized in that, The weight-average molecular weight of the cyclic olefin copolymer is between 10,000 and 1,000,000, preferably between 30,000 and 600,000; and / or, The molecular weight distribution of the cyclic olefin copolymer is between 1 and 10, preferably between 1 and 5; and / or, The glass transition temperature of the cyclic olefin copolymer is 80–300°C, preferably 100–200°C.

3. A method for preparing a cyclic olefin copolymer, characterized in that, The process includes the following steps: in the presence of a catalyst system and a solvent, ethylene, cyclic olefin monomers, and cyclic olefin monomers containing antioxidant functional groups undergo a polymerization reaction.

4. The preparation method according to claim 3, characterized in that, The cyclic olefin monomer is shown in formula (II), wherein R1 and R2 may be the same or different, and their meanings are the same as those in claim 1; n is 0 to 5, preferably 0 to 2; and / or, The monomer containing an antioxidant function is represented by formula (III) wherein R 3、 R4 has the same meaning as in claim 1 ; m is 0 to 5, preferably 0 to 2.

5. The preparation method according to claim 3 or 4, characterized in that, The polymerization reaction temperature is 50–200°C, preferably 90–160°C; and / or, The polymerization reaction time is 0.5 to 120 min, preferably 1 to 30 min.

6. The preparation method according to claim 3 or 4, characterized in that, Catalyst systems for polymerization reactions include: transition metal complexes, organoboron compounds, and organoaluminum compounds; The transition metal complex has the following structure (VI): In formula (VI), R5 and R6 are each independently selected from unsubstituted cyclopentadienyl and its derivatives, indenyl and its derivatives, or fluorenyl and its derivatives. R7 and R8 are independently selected from hydrogen, methyl, ethyl, isopropyl, tert-butyl, phenyl, 2,6-dimethylphenyl, 4-methylphenyl, mestrimethylphenyl, 2,6-diisopropylphenyl, 2,4,6-triisopropylphenyl or 2,6-ditert-butylphenyl; X1 and X2 are monoanion ligands, and X1 and X2 are independently selected from hydrogen, straight-chain or branched aliphatic or alicyclic groups containing 1 to 20 carbon atoms, phenyl, straight-chain or branched alkyl or cyclic aliphatic or aromatic groups substituted with 1 to 20 carbon atoms, straight-chain or branched alkoxy groups containing 1 to 20 carbon atoms, straight-chain or branched alkylamine groups containing 1 to 20 carbon atoms, straight-chain or branched aromaticamine groups containing 1 to 20 carbon atoms, straight-chain or branched silyl groups containing 1 to 20 carbon atoms, borohydride, allyl and allyl derivatives or halogens; M is selected from transition metal atoms, such as zirconium, titanium, vanadium, chromium, hafnium, etc. E is C, Si, or Ge; m = 1 or 2.

7. The preparation method according to claim 6, characterized in that, The organoboron compound is an ionic compound formed by an organoboron anion and a cation; and / or, The organoboron anion is selected from tetraphenylborate, tetra(monofluorophenyl)borate, tetra(difluorophenyl)borate, tetra(trifluorophenyl)borate, tetra(tetrafluorophenyl)borate, tetra(pentafluorophenyl)borate, tetra(tetrafluoromethylphenyl)borate, tetra(tolyl)borate, tetra(xyl)borate, (triphenyl,pentafluorophenyl)borate, [tri(pentafluorophenyl),phenyl]borate, or undecanoyl-7,8-dicarboundecanoate; and / or, The cation is selected from carbium cations, oxonium cations, ammonium cations, phosphonium cations, cycloheptatrienyl cations, or ferrocene cations containing transition metals; Preferably, the carbium cation comprises a trisubstituted carbium cation selected from triphenylcarbium cation and tri(tolyl)carbium cation; Preferably, the ammonium cation includes trialkylammonium cations such as trimethylammonium cation, triethylammonium cation, tripropylammonium cation, and tributylammonium cation; Preferably, the phosphonium cation includes triarylphosphonium cations such as triphenylphosphonium cation, tri(tolyl)phosphonium cation, or tri(xylyl)phosphonium cation; Preferably, the organoaluminum compound is selected from hydrocarbon-substituted aluminum compounds, including but not limited to diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, diphenylaluminum hydride, di-p-tolylaluminum hydride, dibenzylaluminum hydride, phenylethylaluminum hydride, phenyl-n-propylaluminum hydride, p-tolylethylaluminum hydride, p-tolyl-n-propylaluminum hydride, p-tolylisopropylaluminum hydride, benzylethylaluminum hydride, benzyl-n-propylaluminum hydride, benzylisopropylaluminum hydride, ethylaluminum dihydride, butylaluminum dihydride, isobutylaluminum dihydride, octylaluminum dihydride, and pentylaluminum dihydride. One or more of aluminum, diethylethoxide aluminum, dipropylethoxide aluminum, trimethyl aluminum, triethyl aluminum, tri-n-propyl aluminum, triisopropyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, tripentyl aluminum, trihexyl aluminum, tricyclohexyl aluminum, trioctyl aluminum, triphenyl aluminum, tri-p-tolyl aluminum, tribenzyl aluminum, ethyl diphenyl aluminum, ethyl di-p-tolyl aluminum, ethyl dibenzyl aluminum, diethylphenyl aluminum, diethyl p-tolyl aluminum, and diethylbenzyl aluminum; preferably, the organoaluminum compound is one or more of diisobutylaluminum hydride, diethylaluminum hydride, trioctyl aluminum, triisobutyl aluminum, and trimethyl aluminum.

8. The preparation method according to any one of claims 3-7, characterized in that, The pressure of ethylene in the polymerization reaction system is 1 to 12 atm, preferably 1 to 10 atm; Preferably, the concentration of the transition metal complex in the polymerization solution system is 0.1–5 μmol / ml, more preferably 0.2–2 μmol / ml; Preferably, the organoboron compound and organoaluminum compound are used as cocatalysts, and the molar ratio of the organoboron compound to the transition metal complex is (1-10000):1, preferably (1-100):1; Preferably, the molar ratio of the organoaluminum compound to the transition metal complex is (1-10000):1, more preferably (1-100):1; Preferably, the solvent for the polymerization reaction is selected from one or more of aliphatic saturated hydrocarbons, aromatic hydrocarbons, aryl halides and cycloalkanes; more preferably from at least one of pentane, hexane, toluene, xylene, heptane, cyclohexane, cycloheptane, dichloromethane, chlorobenzene, o-dichlorobenzene and dichloroethane, and more preferably from at least one of toluene, hexane and cyclohexane.

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