Modified polyolefin as well as preparation method and application thereof

Abstract

The invention provides antioxidant functional polyolefin containing a 1, 4-dihydropyridine structure as well as a preparation method and application of the antioxidant functional polyolefin. The polyolefin with the antioxidant function comprises a single polyolefin unit and a 1, 4-dihydropyridine substituted polyolefin unit. Wherein the 1, 4-dihydropyridine antioxidant monomer containing double bonds is prepared through a Hantzsch reaction, then polyolefin and the antioxidant monomer react under the conditions of illumination (390 nm), 120 DEG C and no water and oxygen under the catalysis of an iron-based catalyst TBAFeCl4, precipitation washing is conducted with ethyl alcohol, and the antioxidant functional polyolefin material containing the 1, 4-dihydropyridine structure is obtained after filtering and drying are conducted. The prepared polyolefin with the antioxidant function has excellent antioxidant performance and can be applied to the fields of food packaging, biological medicine, health care and the like.

Description

Technical Field

[0001] The present invention relates to the field of functional polymer materials. Further, it relates to a modified polyolefin and its preparation method and application. Background Art

[0002] Polyolefins are a class of thermoplastic resins obtained by homopolymerization or copolymerization of α-olefins and certain cycloolefins. Due to rich raw materials, low price, easy processing and excellent comprehensive properties, they are widely used in daily life fields such as food packaging, building materials, medical and health materials, automotive parts and electronic products. Since polyolefins are composed of inert carbon-hydrogen bonds and carbon-carbon bonds and lack polar functional groups, the materials have high hydrophobicity and are difficult to combine with other materials, which greatly limits their applications. Introducing polar groups into polyolefins can greatly improve various properties including surface adhesion performance, toughness, solvent resistance and miscibility with other polymers, and broaden their application scenarios.

[0003] Polyolefin materials with antioxidant properties have attracted much attention in the fields of active food packaging and tissue repair. For example, polyolefin materials are blended with small molecule antioxidants such as citric acid, tannic acid, and polyphenols, and then further processed into shapes. However, these methods of blending small molecule antioxidants into polyolefin materials have problems such as poor stability, fast migration, and affecting the processing performance of the materials. They are prone to migrate and dissolve during use, and have poor persistence, which to a certain extent limits their development as biomedical, packaging, and health care materials.

[0004] Therefore, how to provide a polyolefin material that not only has antioxidant properties, but also can improve the stability and safety of the material, extend the metabolism or migration time, and improve the bioavailability of the material is of great significance. Summary of the Invention

[0005] In order to solve the technical problems existing in the prior art, the present invention provides a preparation method and application of a polyolefin material with antioxidant function. The present invention modifies and modifies polyolefins to make them have intrinsic antioxidant properties, which can significantly improve the stability and safety of the materials, extend the metabolism or migration time, and improve the bioavailability of the materials.

[0006] The present invention can simply and economically prepare antioxidant polyolefin functional materials. The present invention uses polyolefins with rich varieties and wide applications as the main raw materials, under relatively mild reaction conditions, uses inexpensive catalysts, and through a simple preparation reaction process, obtains antioxidant polyolefin materials with a high modification rate.

[0007] The present invention modifies polyolefins to endow them with intrinsic antioxidant ability, while significantly improving the stability and safety of antioxidant groups, prolonging the metabolism or migration time, and enhancing the material utilization rate.

[0008] The antioxidant polyolefins prepared by the present invention can improve the antioxidant property of the antioxidant polyolefin functional materials by changing the types of polyolefin materials and antioxidant monomers selected, adjusting the usage ratio of the two, controlling the reaction time, etc., and can be applied to multiple fields such as biomedical, food packaging, and health care materials.

[0009] In the prior art, there are mainly two methods for introducing polar groups into the polyolefin structure: free radical copolymerization and copolymerization of simple olefin precursors with polar vinyl monomers. The former has a high polydispersity index and degree of branching, and the latter must use precious metal catalysts. However, the iron-based catalyst used in the preparation method of the antioxidant polyolefins of the present invention (i.e., post-modification of polyolefins) is inexpensive and easily available, the reaction conditions are mild, the preparation method is simple, and an antioxidant polyolefin material with a high modification degree can be obtained.

[0010] The first aspect of the present invention is to provide a modified polyolefin, which comprises a structural unit represented by Formula I and a structural unit represented by Formula II;

[0011]

[0012] In Formula I, R1 is one of H, C1-C4 alkyl, substituted or unsubstituted phenyl, and the repeated R1s are the same or different;

[0013] In Formula II, the general formula of R2 is R2’ is one of H, C1-C4 alkyl, halogen atom, and dihydroxyboron group, and the repeated R2s are the same or different.

[0014] According to some preferred embodiments of the present invention, R1 is one of *-H, *-CH3, and more preferably *-H.

[0015] According to some preferred embodiments of the present invention, R2 in Formula II is

[0016] and more preferably

[0017] According to some preferred embodiments of the present invention, the number average molecular weight of the modified polyolefin is 1000-200000 g / mol, preferably 2400-70000 g / mol; more preferably 3000-50000 g / mol.

[0018] According to some preferred embodiments of the present invention, the modified polyolefin in the present invention is at least one of the following modified polyolefins: polyethylene (including but not limited to LDPE, LLDPE, HDPE), polypropylene (PP), polystyrene (PS), polyisobutene (PIB).

[0019] According to some preferred embodiments of the present invention, the sum of the molar percentage ratios of the structural unit shown in Formula I and the structural unit shown in Formula II is 100 mol%; preferably, the molar percentage of the structural unit shown in Formula II is 0.1 - 20 mol%, such as 0.1, 0.2, 0.3, 0.4, 0.5, 1, 5, 10, 15, 20 mol%, and any two numerical values or any interval of any two numerical values.

[0020] The second aspect of the present invention is to provide a method for preparing a modified polyolefin, preferably a method for preparing the modified polyolefin described in the first aspect, which includes reacting an antioxidant monomer containing a 1,4-dihydropyridine structure with a polyolefin in an anhydrous solvent under heating and irradiation conditions in the presence of an iron-based catalyst TBAFeCl4 to obtain the modified polyolefin;

[0021] Among them, the structural formula of the antioxidant monomer containing a 1,4-dihydropyridine structure is: R2’ is H, an alkyl group with 1 - 4 carbon atoms, a halogen atom, or a dihydroxyboron group.

[0022] According to some preferred embodiments of the present invention, the preparation method further includes the step of preparing the antioxidant monomer containing a 1,4-dihydropyridine structure, and the preparation method includes the following steps:

[0023] (1) Prepare the antioxidant monomer containing a 1,4-dihydropyridine structure by using the Hantzsch reaction: Under the condition of the presence of a catalyst, react methylacrylic acid glycol ester of acetoacetic acid, an aromatic aldehyde compound, an ammonia source compound, and a 1,3-diketone compound by the Hantzsch reaction to obtain the antioxidant monomer containing a 1,4-dihydropyridine structure;

[0024] (2) Under the condition of the presence of the iron-based catalyst TBAFeCl4, react the antioxidant monomer containing a 1,4-dihydropyridine structure obtained in step (1) with a polyolefin in an anhydrous solvent under heating and irradiation conditions to obtain the modified polyolefin.

[0025] According to the present invention, the Hantzsch reaction refers to the process in which two molecules of β-carbonyl compounds (β-ketoesters) undergo condensation reactions with one molecule of aldehyde and one molecule of ammonia respectively, followed by Michael addition to obtain dihydropyridine derivatives (for example, see the reference: Liu G, Pan R, Wei Y, et al. The Hantzsch Reaction in Polymer Chemistry: From Synthetic Methods to Applications [J]. Macromolecular Rapid Communications, 2020. DOI: 10.1002 / marc.202000459).

[0026] In the present invention, the iron-based catalyst TBAFeCl4 can be prepared by existing preparation methods, and the preparation methods include but are not limited to the following methods: In a glove box under a nitrogen atmosphere, ferric chloride (FeCl3) and tetrabutylammonium chloride (TBACl) are mixed in a ratio of 1:1 in an acetonitrile (MeCN) solvent to prepare the iron-based catalyst TBAFeCl4. Preferably, the iron-based catalyst TBAFeCl4 is freshly prepared and used immediately before use.

[0027] In step (1):

[0028] According to some preferred embodiments of the present invention, the catalyst is an amino acid catalyst or other weak acid catalysts other than amino acids, preferably at least one of glycine, proline, and phenylboronic acid.

[0029] According to some preferred embodiments of the present invention, the aromatic aldehyde compound is at least one of 4-isopropylbenzaldehyde, 4-formylphenylboronic acid, 4-fluorobenzaldehyde, and 4-chlorobenzaldehyde, preferably 4-chlorobenzaldehyde.

[0030] According to some preferred embodiments of the present invention, the ammonia source compound is at least one of ammonium acetate, ammonium carbonate, and ammonia water.

[0031] According to some preferred embodiments of the present invention, the 1,3-diketone compound is at least one of 1,3-cyclohexanedione and its derivatives, preferably at least one of 1,3-cyclohexanedione, 1,3-cyclohexanedione substituted with C1-C4 alkyl groups, more preferably at least one of 1,3-cyclohexanedione, 5-methyl-1,3-cyclohexanedione, and 5,5-dimethyl-1,3-cyclohexanedione.

[0032] In step (1):

[0033] According to some preferred embodiments of the present invention, the molar ratio of the aromatic aldehyde compound, the ammonia source compound, the 1,3-diketone compound and ethylene glycol dimethacrylate acetoacetate is 1:(1-2):(1-1.2):(1-1.2), preferably 1:(1.2-1.6):(1-1.2):(1-1.2), more preferably 1:(1.2-1.6):1:1.

[0034] According to some preferred embodiments of the present invention, the molar ratio of the catalyst to the aromatic aldehyde compound is (0.05-0.2):1, preferably (0.1-0.15):1.

[0035] According to some preferred embodiments of the present invention, the reaction temperature in step (1) is 60-90 °C, preferably 70-80 °C. According to some preferred embodiments of the present invention, the reaction time in step (1) is 2-5 hours, preferably 2-4 hours.

[0036] According to some preferred embodiments of the present invention, the Hantzsch reaction in step (1) is carried out in a solvent. Preferably, the solvent is selected from at least one of acetonitrile, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0037] According to some preferred embodiments of the present invention, preferably, relative to 1 mmol of the aromatic aldehyde compound, the amount of the solvent used is 0.5-2 ml.

[0038] According to some preferred embodiments of the present invention, in the Hantzsch reaction in step (1), there is also a post-treatment step, wherein the post-treatment step is to precipitate the mixture with an organic solvent, and then wash and dry to collect the antioxidant monomer containing the 1,4-dihydropyridine structure; preferably, the organic solvent is at least one of acetonitrile, dichloromethane, and methyl tert-butyl ether.

[0039] In step (2):

[0040] According to some preferred embodiments of the present invention, the polyolefin is at least one of polyethylene (including but not limited to LDPE, LLDPE, HDPE), polypropylene (PP), polystyrene (PS), and polyisobutene (PIB), preferably polyethylene.

[0041] According to some preferred embodiments of the present invention, the polyolefin has a data molecular weight in the range of 1000-200000 g / mol, preferably 2400 g / mol-70000 g / mol, more preferably 3000-50000 g / mol, including but not limited to the polyolefins in the examples.

[0042] According to some preferred embodiments of the present invention, the anhydrous organic solvent is at least one of acetonitrile (MeCN), N,N-dimethylformamide (DMF), trifluorotoluene (PhCF3), and chlorobenzene (PhCl), preferably chlorobenzene.

[0043] According to some preferred embodiments of the present invention, the amount of the anhydrous organic solvent is 5 - 10 mL relative to 1 mmol of the antioxidant monomer.

[0044] According to some preferred embodiments of the present invention, the molar ratio of the antioxidant monomer to the polyolefin is (0.05 - 0.45):1, preferably (0.15 - 0.25):1, where the molar amount of the polyolefin is based on the molar amount of the olefin structural unit.

[0045] According to some preferred embodiments of the present invention, the molar ratio of TBAFeCl4 to the polyolefin is (0.001 - 0.005):1, preferably (0.001 - 0.003):1, where the molar amount of the polyolefin is based on the molar amount of the olefin structural unit.

[0046] According to some preferred embodiments of the present invention, the conditions of the irradiation include:

[0047] The irradiation wavelength is 350 nm - 420 nm, preferably 380 - 400 nm, and / or the irradiation time is 15 - 40 hours, preferably 20 - 30 hours.

[0048] According to some preferred embodiments of the present invention, the conditions of the heating reaction include: the temperature is 100 - 140 °C, preferably 110 - 130 °C. According to some preferred embodiments of the present invention, the reaction time is 12 - 48 hours, preferably 20 - 30 hours; preferably,

[0049] The reaction is carried out under mixing conditions, and preferably the mixing method is stirring.

[0050] According to some preferred embodiments of the present invention, after the reaction is completed under heating and irradiation conditions, it further includes a step of post-treating the obtained product mixture to remove small molecules and solvents. Preferably, the post-treatment method includes cooling the product mixture to room temperature, precipitating with ethanol, filtering and washing with ethanol 3 times until all unreacted small molecules are completely removed, and then drying under vacuum at 50 °C for 12 hours to obtain a solid final product, the antioxidant-functional polyolefin.

[0051] The third aspect of the present invention is to provide a modified polyolefin prepared by the preparation method described in the second aspect.

[0052] By the above preparation method, the 1,4-dihydropyridine structure with antioxidant property is introduced into the side chain of polyolefin, and the thus obtained modified polyolefin also has significant antioxidant ability.

[0053] The fourth aspect of the present invention is to provide an application of the modified polyolefin described in the first aspect and the third aspect, preferably in the fields of biomedical use, food packaging, and health care materials.

[0054] In the ranges and any values disclosed in the present invention, the endpoints and any values of the ranges are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. In the following text, in principle, the various technical solutions can be combined with each other to obtain new technical solutions, and this should also be regarded as specifically disclosed herein.

[0055] Compared with the prior art, the present invention has at least the following advantages:

[0056] The present invention can simply and economically prepare antioxidant polyolefin functional materials. The present invention uses polyolefin with rich varieties and wide applications as the main raw material. Under relatively mild reaction conditions, with the use of inexpensive catalysts, through a simple preparation reaction process, antioxidant polyolefin materials with a high modification rate are obtained.

[0057] By modifying and decorating polyolefin, the present invention endows it with intrinsic antioxidant ability, and at the same time significantly improves the stability and safety of antioxidant groups, prolongs the metabolism or migration time, and improves the utilization rate of the materials.

[0058] The antioxidant polyolefin prepared by the present invention can improve the antioxidant property of the antioxidant polyolefin functional material by changing the types of polyolefin materials and antioxidant monomers selected, adjusting the usage ratio of the two, controlling the reaction time, etc., and can be applied to multiple fields such as biomedical use, food packaging, and health care materials.

[0059] In the prior art, there are mainly two methods for introducing polar groups into the polyolefin structure: free radical copolymerization and copolymerization of simple olefin precursors and polar vinyl monomers. The former has a high polydispersity index and degree of branching, and the latter must use precious metal catalysts. However, the iron-based catalyst used in the preparation method of the antioxidant polyolefin of the present invention (i.e., post-modification of polyolefin) is inexpensive and easily available, the reaction conditions are mild, the preparation method is simple, and antioxidant polyolefin materials with a high modification degree can be obtained.

[0060] In summary, the present invention can simply and economically prepare antioxidant polyolefin functional materials. The present invention uses polyolefins with rich varieties and wide applications as the main raw materials, under relatively mild reaction conditions, uses inexpensive catalysts, and through a simple preparation reaction process, obtains antioxidant polyolefin materials with a high modification rate, which has great application potential in the fields of food packaging, biomedicine, health care, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is the synthesis route diagram of the antioxidant monomer containing 1,4-dihydropyridine structure in Preparation Example 1 of the present invention;

[0062] Figure 2 It is the synthesis route diagram of the antioxidant monomer containing 1,4-dihydropyridine structure in Preparation Example 2 of the present invention;

[0063] Figure 3 It is the synthesis route diagram of the antioxidant monomer containing 1,4-dihydropyridine structure in Preparation Example 3 of the present invention;

[0064] Figure 4 It is the synthesis route diagram of the antioxidant monomer containing 1,4-dihydropyridine structure in Preparation Example 4 of the present invention;

[0065] Figure 5 It is the synthesis route diagram of the antioxidant polyolefin functional material containing 1,4-dihydropyridine structure in Example 1 of the present invention.

[0066] Figure 6 It is the synthesis route diagram of the antioxidant polyolefin functional material containing 1,4-dihydropyridine structure in Example 2 of the present invention.

[0067] Figure 7 It is the synthesis route diagram of the antioxidant polyolefin functional material containing 1,4-dihydropyridine structure in Example 3 of the present invention.

[0068] Figure 8 It is the synthesis route diagram of the antioxidant polyolefin functional material containing 1,4-dihydropyridine structure in Example 4 of the present invention.

[0069] Figure 9 It is the synthesis route diagram of the antioxidant polyolefin functional material containing 1,4-dihydropyridine structure in Example 5 of the present invention.

[0070] Figure 10 It is the synthesis route diagram of the antioxidant polyolefin functional material containing 1,4-dihydropyridine structure in Example 6 of the present invention.

[0071] Figure 11 It is the synthesis route diagram of the antioxidant polyolefin functional material containing 1,4-dihydropyridine structure in Example 7 of the present invention.

[0072] Figure 12 This is the synthetic route diagram of the antioxidant polyolefin functional material containing 1,4-dihydropyridine structure in Example 8 of the present invention.

[0073] Figure 13 This is the nuclear magnetic resonance spectrum of the antioxidant monomer containing 1,4-dihydropyridine structure in Preparation Examples 1-4 of the present invention;

[0074] Figure 14 This is the analysis curve of the antioxidant test results of the antioxidant functional polyolefin in Examples 1-8 of the present invention and the polyolefin in Comparative Example 1.

[0075] Figure 15 This is the fluorescence analysis curve of the ethanol immersion solution of the polyolefin composition of Example 1 of the present invention and Comparative Example 2. Detailed implementation manners

[0076] The present invention will be specifically described below in conjunction with specific drawings and examples. It is necessary to point out here that the following examples are only for further illustration of the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0077] In addition, it should be noted that the various specific technical features described in the following detailed implementation manners can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0078] In addition, any combination can be made between various different implementation manners of the present invention as long as it does not violate the idea of the present invention. The technical solutions formed thereby belong to a part of the original public content of this specification and also fall within the protection scope of the present invention.

[0079] Antioxidant performance test method:

[0080] Preparation of ABTS stock solution: Weigh 38.4 mg of ABTS and dissolve it in 10 mL of water to obtain Solution 1 with a concentration of 7 mM; weigh 6.6 mg of K2S2O8 and dissolve it in 10 mL of water to obtain Solution 2 with a concentration of 2.5 mM; directly mix Solution 1 and 2 in a volume ratio of 1:1 and store it in the dark for more than 14 hours to obtain the ABTS stock solution.

[0081] Preparation of ABTS working solution: Take 0.6 mL of the ABTS stock solution and dilute it to about 10 mL with ethanol; measure the absorbance of the solution at a wavelength of 734 nm and adjust the solution concentration to an absorbance of about 0.7-0.8, which is the ABTS working solution.

[0082] Antioxidant test: The polymer was dissolved in DMSO to form a solution with a concentration of 0.1 mg / mL. 20 μL of the polymer solution was added to 380 μL of the ABTS working solution, and the change in absorbance value at a wavelength of 734 nm was recorded.

[0083] The present invention will be described in detail below through examples.

[0084] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods.

[0085] Unless otherwise specified, the materials, reagents, etc. used in the following examples can all be obtained from commercial sources.

[0086] Specifications of some raw materials:

[0087] LDPE: Mn = 30423 g / mol, Mw = 177700 g / mol,

[0088] LLDPE: Mn = 68110 g / mol, Mw = 229639 g / mol,

[0089] PP: Mn = 12122 g / mol, Mw = 27466 g / mol,

[0090] PS: Mn = 130714 g / mol, Mw = 265657 g / mol,

[0091] PIB: Mn = 2497 g / mol, Mw = 12770 g / mol,

[0092] The above polyolefin materials were all purchased from Macklin.

[0093] The iron-based catalyst was self-prepared: In a glove box under a nitrogen atmosphere, ferric chloride (FeCl3) and tetrabutylammonium chloride (TBACl) were mixed in a 1:1 ratio in an acetonitrile (MeCN) solvent to prepare the iron-based catalyst TBAFeCl4.

[0094] Preparation Example 1

[0095] Preparation of the antioxidant monomer containing a 1,4-dihydropyridine structure:

[0096] The reaction equation is as Figure 1As shown, AEMA (428 mg, 2 mmol), 5,5-dimethyl-1,3-cyclohexanedione (280 mg, 2 mmol), 4-chlorobenzaldehyde (281 mg, 2 mmol), and ammonium acetate (231 mg, 3 mmol) were successively added into a Schlenk tube. After adding 2 mL of acetonitrile solvent, glycine catalyst (22.5 mg, 0.3 mmol) was added. The mixture was heated to 70 °C under stirring and reacted for 4 hours. Subsequently, the system was precipitated with ice water, washed alternately with water and ether three times, filtered by suction, and freeze-dried to obtain an antioxidant monomer 1 in the form of a yellow solid.

[0097] Preparation Example 2

[0098] Preparation of an antioxidant monomer containing a 1,4-dihydropyridine structure:

[0099] The reaction equation is as Figure 2 As shown, AEMA (428 mg, 2 mmol), 5,5-dimethyl-1,3-cyclohexanedione (280 mg, 2 mmol), 4-isopropylbenzaldehyde (296 mg, 2 mmol), and ammonium acetate (231 mg, 3 mmol) were successively added into a Schlenk tube. After adding 2 mL of acetonitrile solvent, glycine catalyst (22.5 mg, 0.3 mmol) was added. The mixture was heated to 70 °C under stirring and reacted for 4 hours. Subsequently, the system was precipitated with ice water, washed alternately with water and ether three times, filtered by suction, and freeze-dried to obtain an antioxidant monomer 2 in the form of a yellow solid.

[0100] Preparation Example 3

[0101] Preparation of an antioxidant monomer containing a 1,4-dihydropyridine structure:

[0102] The reaction equation is as Figure 3 As shown, AEMA (428 mg, 2 mmol), 5,5-dimethyl-1,3-cyclohexanedione (280 mg, 2 mmol), 4-formylphenylboronic acid (300 mg, 2 mmol), and ammonium acetate (231 mg, 3 mmol) were successively added into a Schlenk tube. After adding 2 mL of acetonitrile solvent, glycine catalyst (22.5 mg, 0.3 mmol) was added. The mixture was heated to 70 °C under stirring and reacted for 4 hours. Subsequently, the system was precipitated with ice water, washed alternately with water and ether three times, filtered by suction, and freeze-dried to obtain an antioxidant monomer 3 in the form of a yellow solid.

[0103] Preparation Example 4

[0104] Preparation of an antioxidant monomer containing a 1,4-dihydropyridine structure:

[0105] The reaction equation is as Figure 4As shown, AEMA (428 mg, 2 mmol), 5,5-dimethyl-1,3-cyclohexanedione (280 mg, 2 mmol), 4-fluorobenzaldehyde (248 mg, 2 mmol), and ammonium acetate (231 mg, 3 mmol) were successively added into a Schlenk tube. After adding 2 mL of acetonitrile solvent, glycine catalyst (22.5 mg, 0.3 mmol) was added. The mixture was heated to 70 °C under stirring and reacted for 4 hours. Subsequently, the system was precipitated with ice water, washed alternately with water and ether three times, filtered by suction, and freeze-dried to obtain the antioxidant monomer 4 in the form of a yellow solid.

[0106] Figure 13 This is the nuclear magnetic resonance spectrum of the antioxidant monomer containing 1,4-dihydropyridine structure in Preparation Examples 1-4 of the present invention. It can be seen from Figure 13 that the present invention uses the Hantzsch reaction and obtains the antioxidant monomer containing 1,4-dihydropyridine structure with the structure shown in Figure 13 by the methods in Preparation Examples 1-4.

[0107] Example 1

[0108] The reaction equation is as shown in Figure 5 shown.

[0109] The iron-based catalyst TBAFeCl4 (1.7 mg, 0.004 mmol), LDPE (56.7 mg, 2.0 mmol, Mn = 30423 g / mol, Mw = 177700 g / mol, )), antioxidant monomer 1 (183.2 mg, 0.4 mmol), and PhCl (3.0 mL) were successively added into a Schlenk tube (50 mL). The test tube was sealed with a rubber stopper and transferred out of the glove box. Under the irradiation of a 390 nm LED, the obtained mixture was stirred at 120 °C for 24 hours. After cooling to room temperature, ethanol was added to precipitate the product. After filtration, it was washed with ethanol three times until all unreacted small molecules were completely removed. After drying under vacuum at 50 °C for 12 hours, the solid final product antioxidant functional polyolefin P1 was obtained.

[0110] Example 2

[0111] The reaction equation is as shown in Figure 6 shown.

[0112] The iron-based catalyst TBAFeCl4 (1.7 mg, 0.004 mmol), LDPE (56.7 mg, 2.0 mmol, Mn = 30423 g / mol, Mw = 177700 g / mol, ) Antioxidant monomer 2 (186.2 mg, 0.4 mmol), PhCl (3.0 mL) were successively added into a Schlenk tube (50 mL). The tube was sealed with a rubber stopper and transferred out of the glove box. Under 390 nm LED irradiation, the resulting mixture was stirred at 120 °C for 24 h. After cooling to room temperature, ethanol was added thereto for precipitation (of the product), and after filtration, it was washed with ethanol three times until all unreacted small molecules were completely removed. After drying under vacuum at 50 °C for 12 h, the final product, antioxidant-functional polyolefin P2 in solid form, was obtained.

[0113] Example 3

[0114] The reaction equation is as Figure 7 shown.

[0115] The iron-based catalyst TBAFeCl4 (1.7 mg, 0.004 mmol), LDPE (56.7 mg, 2.0 mmol, Mn = 30423 g / mol, Mw = 177700 g / mol, )), antioxidant monomer 3 (186.9 mg, 0.4 mmol), PhCl (3.0 mL) were successively added into a Schlenk tube (50 mL). The tube was sealed with a rubber stopper and transferred out of the glove box. Under 390 nm LED irradiation, the resulting mixture was stirred at 120 °C for 24 h. After cooling to room temperature, ethanol was added thereto for precipitation (of the product), and after filtration, it was washed with ethanol three times until all unreacted small molecules were completely removed. After drying under vacuum at 50 °C for 12 h, the final product, antioxidant-functional polyolefin P3 in solid form, was obtained.

[0116] Example 4

[0117] The reaction equation is as Figure 8 shown.

[0118] The iron-based catalyst TBAFeCl4 (1.7 mg, 0.004 mmol), LDPE (56.7 mg, 2.0 mmol, Mn = 30423 g / mol, Mw = 177700 g / mol, )), antioxidant monomer 4 (176.6 mg, 0.4 mmol), PhCl (3.0 mL) were successively added into a Schlenk tube (50 mL). The tube was sealed with a rubber stopper and transferred out of the glove box. Under 390 nm LED irradiation, the resulting mixture was stirred at 120 °C for 24 h. After cooling to room temperature, ethanol was added thereto for precipitation (of the product), and after filtration, it was washed with ethanol three times until all unreacted small molecules were completely removed. After drying under vacuum at 50 °C for 12 h, the final product, antioxidant-functional polyolefin P4 in solid form, was obtained.

[0119] Example 5

[0120] The reaction equation is as follows Figure 9 shown

[0121] The iron-based catalyst TBAFeCl4 (1.7 mg, 0.004 mmol), LLDPE (56.1 mg, 2.0 mmol, Mn = 68110 g / mol, Mw = 229639 g / mol, ) and antioxidant monomer 1 (183.2 mg, 0.4 mmol) and PhCl (3.0 mL) were successively added into a Schlenk tube (50 mL). The tube was sealed with a rubber stopper and transferred out of the glove box. Under 390 nm LED irradiation, the resulting mixture was stirred at 120 °C for 24 h. After cooling to room temperature, ethanol was added thereto for precipitation (of the product), and after filtration, it was washed 3 times with ethanol until the unreacted small molecules were completely removed. After drying under vacuum at 50 °C for 12 h, the final solid product, antioxidant-functional polyolefin P5, was obtained

[0122] Example 6

[0123] The reaction equation is as follows Figure 10 shown

[0124] The iron-based catalyst TBAFeCl4 (1.7 mg, 0.004 mmol), PP (84.5 mg, 2.0 mmol, Mn = 12122 g / mol, Mw = 27466 g / mol, ) and antioxidant monomer 1 (183.2 mg, 0.4 mmol) and PhCl (3.0 mL) were successively added into a Schlenk tube (50 mL). The tube was sealed with a rubber stopper and transferred out of the glove box. Under 390 nm LED irradiation, the resulting mixture was stirred at 110 °C for 30 h. After cooling to room temperature, ethanol was added thereto for precipitation (of the product), and after filtration, it was washed 3 times with ethanol until the unreacted small molecules were completely removed. After drying under vacuum at 50 °C for 12 h, the final solid product, antioxidant-functional polyolefin P6, was obtained

[0125] Example 7

[0126] The reaction equation is as follows Figure 11 shown

[0127] The iron-based catalyst TBAFeCl4 (1.7 mg, 0.004 mmol), PS (207.3 mg, 2.0 mmol, Mn = 130714 g / mol, Mw = 265657 g / mol, ) Antioxidant monomer 1 (183.2 mg, 0.4 mmol) and PhCl (3.0 mL) were successively added into a Schlenk tube (50 mL). The tube was sealed with a rubber stopper and transferred out of the glove box. Under 390 nm LED irradiation, the resulting mixture was stirred at 130 °C for 24 h. After cooling to room temperature, ethanol was added thereto for precipitation (of the product), and after filtration, it was washed with ethanol three times until all unreacted small molecules were completely removed. After drying under vacuum at 50 °C for 12 h, the final product, antioxidant-functional polyolefin P7, was obtained as a solid.

[0128] Example 8

[0129] The reaction equation is as Figure 12 shown.

[0130] The iron-based catalyst TBAFeCl4 (1.7 mg, 0.004 mmol), PIB (112.9 mg, 2.0 mmol, Mn = 2497 g / mol, Mw = 12770 g / mol, ) and antioxidant monomer 1 (183.2 mg, 0.4 mmol) and PhCF3 (3.0 mL) were successively added into a Schlenk tube (50 mL). The tube was sealed with a rubber stopper and transferred out of the glove box. Under 390 nm LED irradiation, the resulting mixture was stirred at 125 °C for 36 h. After cooling to room temperature, ethanol was added thereto for precipitation (of the product), and after filtration, it was washed with ethanol three times until all unreacted small molecules were completely removed. After drying under vacuum at 50 °C for 12 h, the final product, antioxidant-functional polyolefin P8, was obtained as a solid.

[0131] Example 9

[0132] The iron-based catalyst TBAFeCl4 (0.85 mg, 0.002 mmol), LDPE (56.7 mg, 2.0 mmol, Mn = 30423 g / mol, Mw = 177700 g / mol, ) and antioxidant monomer 1 (91.6 mg, 0.2 mmol) and acetonitrile (3.0 mL) were successively added into a Schlenk tube (50 mL). The tube was sealed with a rubber stopper and transferred out of the glove box. Under 360 nm LED irradiation, the resulting mixture was stirred at 110 °C for 24 h. After cooling to room temperature, ethanol was added thereto for precipitation (of the product), and after filtration, it was washed with ethanol three times until all unreacted small molecules were completely removed. After drying under vacuum at 50 °C for 12 h, the final product, antioxidant-functional polyolefin P9, was obtained as a solid.

[0133] Example 10

[0134] The iron-based catalyst TBAFeCl4 (2.6 mg, 0.006 mmol), LDPE (56.7 mg, 2.0 mmol, Mn = 30423 g / mol, Mw = 177700 g / mol, ), the antioxidant monomer 1 (274.8 mg, 0.6 mmol), and N,N-dimethylformamide (3.0 mL) were successively added into a Schlenk tube (50 mL). The tube was sealed with a rubber stopper and taken out of the glove box. Under irradiation with a 410 nm LED, the resulting mixture was stirred at 130 °C for 40 h. After cooling to room temperature, ethanol was added thereto for precipitation (of the product), and after filtration, it was washed with ethanol three times until the unreacted small molecules were completely removed. After drying under vacuum at 50 °C for 12 h, the final product, the antioxidant-functional polyolefin P10, in solid form was obtained.

[0135] Adopt 1 1H nuclear magnetic resonance to confirm the content of the structural unit containing 1,4-dihydropyridine in the obtained antioxidant-functional polyolefin.

[0136] It was detected that the content of the structural unit containing 1,4-dihydropyridine in the antioxidant-functional polyolefins P1-P10 was between 0.1 - 20 mol%, wherein the total content of the respective structural units of the polyolefin was 100 mol%.

[0137] Comparative Example 1

[0138] The formulation of Preparation Example 1 was used, with the difference that the catalyst used in the formulation was benzoyl peroxide (BPO), and the antioxidant-functional polyolefin P11 was obtained by the same preparation method. It was detected that the content of the structural unit containing 1,4-dihydropyridine in the antioxidant-functional polyolefin P11 was not zero, but was significantly lower than the content of the structural unit containing 1,4-dihydropyridine in P1-P10.

[0139] Comparative Example 2

[0140] LDPE (56.7 g, 2.0 mol, Mn = 30423 g / mol, Mw = 177700 g / mol, ) and the antioxidant monomer 1 (45.8 g, 0.1 mol) were kneaded to obtain a physically blended and uniform functional polyolefin material P12.

[0141] Test Example 1

[0142] The polyolefin materials described in Examples 1 - 10 and Comparative Example 1 were subjected to an antioxidant test:

[0143] Comparison of the antioxidant properties of Examples 1 - 10 and Comparative Example 1:

[0144] The antioxidant test results of some examples and comparative examples are asFigure 14 As shown, the types of polyolefin materials, the structures of antioxidant monomers, and the types of catalysts all affect the antioxidant ability of antioxidant-functional polyolefins.

[0145] Comparing P1 - P8 with the comparative example P11, it can be seen that the antioxidant performance of P1 - P8 is significantly better than that of P11. Compared with BPO, the iron-based catalyst TBAFeCl4 in the present invention shows excellent performance in catalyzing the alkylation of polyolefin - CH - bonds. This shows that through the modification method of the present invention, inert polyolefin materials are successfully grafted with antioxidant monomers containing 1,4-dihydropyridine structures under relatively mild conditions. After verification, the polyolefins obtained in Example 9 and Example 10 have good antioxidant ability.

[0146] From the comparison between P1 - P5 and P6 - P8, it can be known that when the polyolefin material in this invention is polyethylene, the antioxidant performance is better. This may be because the modification rate of this iron-based catalyst for grafting antioxidant monomers onto polyethylene is higher. The steric hindrance on the C atoms of the main chains of polypropylenes (PP), polyisobutylenes (PIB), and polystyrenes (PS) gradually increases, affecting the grafting rate and thus the antioxidant ability gradually weakens. Comparing P1, P2, P3, and P4 with each other, it can be found that the structure of the antioxidant monomer has a certain influence on the antioxidant ability of the final product functional polyolefin, and its antioxidant ability can be regulated by grafting antioxidant monomers with different structures.

[0147] In addition, the prepared functional polyolefin material has good antioxidant ability and improved hydrophilicity, and is expected to be applied in the fields of food packaging, biomedicine, health care, etc.

[0148] Through the post-treatment step of the present invention, unreacted small molecules are removed. It is known that the solid final product obtained in the examples of the present invention is a polymer and does not contain small molecules. Through the comparison of antioxidant performance, it can be seen that the products in the examples of the present invention have good antioxidant performance, indicating that the antioxidant monomers in the present invention are grafted onto the polyolefin, which is different from the polyolefin composition obtained by blending.

[0149] Test Example 2

[0150] Respectively, 5 mg of P1 (Example 1) and P12 (Comparative Example 2) were placed in 1 mL of ethanol solution and soaked. After 7 days, the soaked liquid was taken and placed in a cuvette, and fluorescence intensity was measured using 360 nm as the excitation wavelength.

[0151] The test results are as Figure 15As shown, only the antioxidant monomer in the system may exhibit fluorescence emission, and its maximum fluorescence emission wavelength is located at 428 nm. As can be seen from the figure, in Comparative Example 2, the physical blending method was used, and the fluorescence of the immersion liquid was significantly higher than that of Example 1 (grafting), indicating that directly blending the antioxidant with the polyolefin material has problems of poor stability and easy migration and dissolution, which limits its development as a biomedical, packaging, and health care material. The method provided by the present invention is to directly covalently graft the antioxidant onto the main body of the polyolefin material, which can greatly reduce the problem of migration and dissolution during use.

[0152] It should be noted that the above-described embodiments are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words rather than limiting words. Modifications can be made to the present invention within the scope of the claims of the present invention as provided, and the present invention can be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications having the same function.

[0153] All publications, patent applications, patents, and other references mentioned in this specification are hereby incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0154] When this specification uses prefixes such as "known to those skilled in the art", "prior art", or similar terms to derive materials, substances, methods, steps, devices, or components, etc., the objects derived by such prefixes cover those commonly used in the art at the time when this application is filed, but also include those that are not commonly used at present but will become commonly recognized in the art as suitable for similar purposes.

[0155] In the scope disclosed in this application document, the endpoints and any values of the ranges are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. In the following text, in principle, the various technical solutions can be combined with each other to obtain new technical solutions, which should also be regarded as specifically disclosed herein.

[0156] In the context of this specification, except for the content clearly stated, any matters or things not mentioned directly apply to those known in the art without any change.

[0157] Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or technical concepts thus formed shall be regarded as part of the original disclosure or original record of the present invention, and shall not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider such combination to be obviously unreasonable.

Claims

1. A modified polyolefin, wherein the modified polyolefin comprises a structural unit represented by Formula I and a structural unit represented by Formula II; In Formula I, R1 is one of H, C1-C4 alkyl, substituted or unsubstituted phenyl, and the repeated R1s are the same or different; In formula II, the general formula of R2 is R2’ is one of H, C1-C4 alkyl, halogen atom, and dihydroxyboron group, and the repeated R2s are the same or different.

2. The modified polyolefin according to claim 1, wherein: R1 is one of *-H, *-CH3, and / or; In formula II, R2 is one of; and / or, The number average molecular weight of the modified polyolefin is 1000-200000 g / mol; and / or, The sum of the molar percentage ratios of the structural unit represented by Formula I and the structural unit represented by Formula II is 100 mol%; preferably, The molar percentage of the structural unit represented by Formula II is 0.1-20 mol%.

3. A method for preparing a modified polyolefin, preferably a method for preparing the modified polyolefin according to claim 1 or 2, comprising reacting an antioxidant monomer containing a 1,4-dihydropyridine structure with a polyolefin in an anhydrous solvent under heating and irradiation conditions in the presence of an iron-based catalyst TBAFeCl4 to obtain the modified polyolefin; Among them, The structural formula of the antioxidant monomer containing a 1,4-dihydropyridine structure is as follows: R2’ is H, an alkyl group with 1 - 4 carbon atoms, a halogen atom, or a dihydroxyboron group.

4. The preparation method according to claim 3, characterized in that, It further comprises the step of preparing the antioxidant monomer containing a 1,4-dihydropyridine structure, and the preparation method comprises the following steps: (1) Preparing the antioxidant monomer containing a 1,4-dihydropyridine structure by Hantzsch reaction: Under the condition of a catalyst, reacting ethylene glycol methacrylate acetoacetate, an aromatic aldehyde compound, an ammonia source compound and a 1,3-diketone compound by Hantzsch reaction to obtain the antioxidant monomer containing a 1,4-dihydropyridine structure; (2) Under the condition of an iron-based catalyst TBAFeCl4, reacting the antioxidant monomer containing a 1,4-dihydropyridine structure obtained in step (1) with a polyolefin in an anhydrous solvent under heating and irradiation conditions to obtain the modified polyolefin.

5. The preparation method according to claim 4, wherein: In step (1): The catalyst is an amino acid catalyst or other weak acid catalysts other than amino acids, preferably at least one of glycine, proline, and phenylboric acid; and / or, The aromatic aldehyde compound is at least one of 4-isopropylbenzaldehyde, 4-formylphenylboronic acid, 4-fluorobenzaldehyde, and 4-chlorobenzaldehyde; and / or, The ammonia source compound is at least one of ammonium acetate, ammonium carbonate, and ammonia water; and / or, The 1,3-diketone compound is at least one of 1,3-cyclohexanedione and its derivatives, preferably at least one of 1,3-cyclohexanedione, C1-C4 alkyl-substituted 1,3-cyclohexanedione, more preferably at least one of 1,3-cyclohexanedione, 5-methyl-1,3-cyclohexanedione, and 5,5-dimethyl-1,3-cyclohexanedione; and / or.

6. The preparation method according to claim 4, wherein: In step (1): The feeding molar ratio of the aromatic aldehyde compound, the ammonia source compound, the 1,3-diketone compound and ethylene glycol methacrylate acetoacetate is 1:(1-2):(1-1.2):(1-1.2), preferably 1:(1.2-1.6):(1-1.2):(1-1.2); and / or, The molar ratio of the catalyst to the aromatic aldehyde compound is (0.05 - 0.2):1, preferably (0.1 - 0.15):1; and / or, The reaction temperature is 60 - 90 °C, preferably 70 - 80 °C; and / or, the reaction time is 2 - 5 hours, preferably 2 - 4 hours.

7. The preparation method according to claim 4, wherein: In step (1), the Hantzsch reaction is carried out in a solvent. Preferably, the solvent is selected from at least one of acetonitrile, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide; and / or, preferably, relative to 1 mmol of the aromatic aldehyde compound, the amount of the solvent used is 0.5 - 2 ml; and / or, In step (1) of the Hantzsch reaction, there is also a post-treatment step. The post-treatment step is to precipitate the mixture with an organic solvent, followed by washing, drying, and collecting the antioxidant monomer containing the 1,4-dihydropyridine structure; preferably, the organic solvent is at least one of acetonitrile, dichloromethane, and methyl tert-butyl ether.

8. The preparation method according to claim 4, wherein: In step (2): The polyolefin is at least one of polyethylene, polypropylene, polystyrene, and polyisobutene, and / or, the data molecular weight of the polyolefin is 1000 - 200000 g / mol; and / or, The anhydrous organic solvent is at least one of acetonitrile, N,N-dimethylformamide, trifluorotoluene, and chlorobenzene, preferably chlorobenzene; and / or, relative to 1 mmol of the antioxidant monomer, the amount of the anhydrous organic solvent used is 5 - 10 mL; and / or, The molar ratio of the antioxidant monomer to the polyolefin is (0.05 - 0.45):1, preferably (0.15 - 0.25):1, where the molar amount of the polyolefin is calculated based on the molar amount of the olefin structural unit; and / or, The molar ratio of TBAFeCl4 to the polyolefin is (0.001 - 0.005):1, preferably (0.001 - 0.003):1, where the molar amount of the polyolefin is calculated based on the molar amount of the olefin structural unit.

9. The preparation method according to any one of claims 3 - 8, wherein: The conditions of the irradiation include: The irradiation wavelength is 350 nm - 420 nm, preferably 380 - 400 nm, and / or, the irradiation time is 15 - 40 hours, preferably 20 - 30 hours; and / or, The conditions of the reaction include: the temperature is 100 - 140 °C, preferably 110 - 130 °C; and / or, the reaction time is 12 - 48 hours, preferably 20 - 30 hours; preferably, The reaction is carried out under a mixing condition, and preferably the mixing method is stirring; and / or, After the reaction is completed under heating and irradiation conditions, there is also a step of post-treating the obtained product mixture to remove small molecules and solvents.

10. A modified polyolefin prepared by the preparation method according to any one of claims 3 - 9.

11. Use of the modified polyolefin according to claim 1 or 2 or 10, preferably for use in the fields of biomedical use, food packaging, and health care materials.

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