A method for the solution process, synergistic catalytic preparation of post-functionalized polyolefins

Abstract

This invention discloses a solution-based synergistic catalytic method for preparing post-functionalized polyolefins, belonging to the field of polymer material modification technology. The method includes the following preparation steps: adding polyolefin, graft monomer, and catalyst to an organic solvent, stirring until homogeneous, and heating to react, thereby obtaining the post-functionalized polyolefin; wherein the catalyst is a combination of a first catalyst and a second catalyst; and the first catalyst is selected from tert-butyl nitrite, and the second catalyst is selected from N-hydroxysuccinimide and / or N-hydroxyphthalimide. This invention utilizes a synergistic catalytic system composed of tert-butyl nitrite and N-hydroxysuccinimide and / or N-hydroxyphthalimide to activate the C-H bonds of polyolefins in an organic solvent via a free radical mechanism, thereby grafting polar functionalized graft monomers onto the main chain of various polyolefins.

Description

Technical Field

[0001] This invention belongs to the field of polymer material modification technology, and particularly relates to a method for preparing post-functionalized polyolefins by solution-based synergistic catalysis. Background Technology

[0002] Polyolefin materials, mainly including polyethylene (PE) and polypropylene (PP), have become indispensable basic materials in various sectors of the national economy due to their excellent comprehensive properties, low price, and good processability. However, the molecular chains of polyolefins are entirely composed of non-polar carbon-carbon and carbon-hydrogen bonds. This chemical inertness results in poor hydrophilicity, low surface energy, and poor compatibility with polar substances, making it difficult to meet the urgent needs of high-end application fields for material functionalization (such as antibacterial, flame retardant, adhesive, printing and dyeing, and biocompatibility).

[0003] To address the aforementioned issues, various functionalization modification strategies for polyolefins have been developed in this field. While direct copolymerization of olefins with polar monomers can introduce polar groups at the molecular level, polar monomers easily deactivate polymerization catalysts, resulting in complex processes and high costs. Surface treatment methods only improve surface properties, with short-lived effects and a tendency to damage the matrix. Physical blending methods are limited by poor compatibility between components, often sacrificing the mechanical properties of the material. Against this backdrop, post-functionalization modification technology, namely chemical grafting modification of synthesized polyolefins, has become an important research direction for overcoming the functionalization bottleneck of polyolefin materials.

[0004] Depending on the reaction medium, post-functionalization modification can be divided into melt processing and solution processing. Melt processing is simple and easy to scale up for continuous production, but reaction selectivity is difficult to control under high temperature and high shear stress conditions, leading to severe side reactions. In contrast, solution processing is carried out under relatively mild conditions, allowing the polyolefin molecular chains to extend in the solvent, resulting in high accessibility of reaction sites, which is beneficial for achieving uniform modification. Furthermore, it facilitates in-depth research into the reaction mechanism and precise control of the reaction process, thus possessing unique advantages in the preparation of high-value-added polyolefin functional materials.

[0005] Traditional solution-based free radical grafting typically uses benzoyl peroxide (BPO) or azobisisobutyronitrile (AIBN) as initiators. However, the free radicals generated during the thermal decomposition of these conventional initiators are highly reactive and have poor selectivity. While abstracting hydrogen atoms from the polyolefin molecular chain, they readily induce chain breakage in the polyolefin backbone, leading to a significant decrease in molecular weight and severely affecting the intrinsic properties of the material. Achieving highly selective and controllable grafting of polyolefins under mild conditions has always been a key technical bottleneck that those skilled in the art are striving to overcome.

[0006] It is worth noting that the direct functionalization of carbon-hydrogen bonds (CH bonds) has always been a research frontier and hot topic in the field of small molecule organic synthesis. In recent years, tert-butyl nitrite (TBN), as a green and efficient free radical initiator and nitrating agent, has been widely used for the activation and transformation of small molecule CH bonds. Studies have shown that TBN decomposes under mild thermal conditions to produce tert-butoxy radicals and nitric oxide (NO), which can work synergistically to achieve selective hydrogen abstraction and functionalization of small molecule substrate CH bonds. Inspired by this, if this efficient and mild small molecule CH activation strategy can be extended to the solution system of polyolefin macromolecules, and a synergistic catalytic system composed of TBN and N-hydroxyphthalimide (NHPI) / N-hydroxyphthalimide (NHS) is utilized, it is expected to achieve efficient graft modification of polyolefins under mild solution conditions, while effectively suppressing the degradation side reactions of the main chain by utilizing the free radical capturing properties of NO. However, no relevant technical solutions have been reported to date. Summary of the Invention

[0007] Based on the aforementioned defects and shortcomings of existing technologies, this invention aims to provide a method for efficient, controllable, and deep functionalization modification of polyolefins, overcoming problems such as severe side reactions, low grafting efficiency and uniformity, and harsh reaction conditions in existing technologies. The method of this invention selectively introduces diverse polar functional groups into the polyolefin molecular chain while maximally preserving its excellent processing and mechanical properties, thus achieving efficient, controllable, and highly selective functionalization modification of polyolefin materials.

[0008] The purpose of this invention is to provide a solution-based co-catalytic method for preparing post-functionalized polyolefins, comprising the following preparation steps:

[0009] Polyolefin, grafted monomer and catalyst are added to an organic solvent, stirred evenly, and heated to react, thereby obtaining the post-functionalized polyolefin.

[0010] The catalyst is a combination of a first catalyst and a second catalyst; and the first catalyst is selected from tert-butyl nitrite, and the second catalyst is selected from N-hydroxysuccinimide and / or N-hydroxyphthalimide.

[0011] This invention employs a synergistic catalytic system composed of tert-butyl nitrite, N-hydroxysuccinimide, and / or N-hydroxyphthalyl. In an organic solvent, through a free radical mechanism, the activation of the CH bond in polyolefins is achieved, thereby grafting polar functionalized graft monomers onto the main chain of various polyolefins.

[0012] In some embodiments of the present invention, the polyolefin is selected from at least one of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), and polyolefin elastomer (POE).

[0013] In some embodiments of the present invention, the grafting monomer is selected from at least one of maleic anhydride, (meth)acrylic acid, (meth)acrylate, and ethylene. Examples of such grafting monomers include maleic anhydride (MAH), (meth)acrylic acid (AA / MAA), butyl (meth)acrylate (BA / MBA), methyl (meth)methacrylate (MA / MMA), polyoxyethylene (meth)acrylate, glycidyl (meth)acrylate (GA / GMA), styrene, and vinylsilanes (such as vinyltrimethoxysilane, vinyltriethoxysilane, etc.).

[0014] In some embodiments of the present invention, the mass ratio of the polyolefin to the grafted monomer is 100:1 to 30. Examples of such mass ratios include 100:5, 100:10, 100:15, 100:20, and 100:25.

[0015] In some embodiments of the present invention, the mass ratio of the polyolefin to the tert-butyl nitrite is 100:0.5 to 10. Examples of such mass ratios include 100:1, 100:1.5, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, and 100:9.

[0016] In some embodiments of the present invention, the molar ratio of the first catalyst to the second catalyst is 1:0.2 to 5. Examples of such molar ratios include 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, and 1:4.5.

[0017] In some embodiments of the present invention, the organic solvent is selected from at least one of aromatic hydrocarbon solvents and halogenated hydrocarbon solvents. Examples of such organic solvents include tetrachloroethane, toluene, xylene, chlorobenzene, dichlorobenzene, tetrahydronaphthalene, and decahydronaphthalene.

[0018] In some embodiments of the present invention, the reaction temperature of the heating reaction is 80~140℃, preferably 100~120℃.

[0019] In some embodiments of the present invention, the reaction time of the heating reaction is 0.5 to 2 h, preferably 0.5 to 1 h.

[0020] In some embodiments of the present invention, the heating reaction further includes a step of precipitating the polymer with a precipitant and / or removing small molecule impurities. The precipitant is selected from acetone, methanol, ethanol, or combinations thereof, or an aqueous solution thereof; the method for removing small molecule impurities includes Soxhlet extraction.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention is the first to introduce a TBN-NHPI / NHS synergistic catalytic system into the solution phase post-functionalization modification of polyolefin macromolecules. This system utilizes the tert-butoxy radical generated by the thermal decomposition of TBN under mild conditions to selectively extract hydroxyl hydrogens from NHPI or NHS, generating highly reactive N-oxygen radicals, thereby achieving selective activation and grafting of CH bonds on the polyolefin molecular chain. This mechanism avoids the random attack on the polyolefin backbone by traditional radical initiators, significantly improving the selectivity of the reaction.

[0023] Nitric oxide (NO) produced by the decomposition of TBN is a stable free radical scavenger, which can promptly capture any polyolefin macromolecular free radicals that may be generated in the system, forming relatively stable intermediates. This effectively inhibits the β-fracture degradation reaction that is difficult to avoid in traditional solution grafting. Gel permeation chromatography (GPC) tests show that the molecular weight and molecular weight distribution of the polyolefin remain basically unchanged before and after modification, and the intrinsic properties of the material are preserved to the greatest extent.

[0024] Thanks to the high reactivity of N-oxygen radicals and the sustained and uniform initiation ability of TBN in solution systems, the method of this invention achieves efficient grafting and uniform distribution of polar functional groups on polyolefin molecular chains. FTIR and NMR results show that the grafting rate is significantly improved compared to traditional peroxide or azo initiation systems, and the functional group distribution is more uniform.

[0025] The solution reaction system allows the polyolefin molecular chains to fully extend, provides high accessibility to reaction sites, and maintains a relatively low reaction temperature, thus avoiding the thermal oxidative degradation of polyolefins caused by high temperatures. Simultaneously, the solution system facilitates sampling and monitoring of the reaction process, enabling in-depth research into reaction kinetics and grafting mechanisms, and allowing for precise control of the grafting process.

[0026] tert-butyl nitrite, as a green nitrating agent, primarily produces tert-butanol as a reaction byproduct, making it environmentally friendly. Furthermore, this catalytic system is applicable not only to various polyolefin substrates but also allows for the flexible introduction of diverse polar functional groups such as carboxyl, anhydride, epoxy, and silane groups by changing different functional monomers, meeting the varied performance requirements of different applications. The post-functionalized polyolefins prepared by this method can be used as compatibilizers, bonding promoters, and modifiers for various high-performance polyolefin alloys, demonstrating broad application prospects. Attached Figure Description

[0027] Figure 1 The DSC spectrum of the polypropylene used in Example 1;

[0028] Figure 2 The image shows the DSC spectrum of the post-functionalized polyolefin obtained in Example 1. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0030] Unless otherwise specified, all materials and reagents used are commercially available.

[0031] For maleic anhydride grafted products, the grafting rate was determined by alkaline titration. Specifically, the purified product was dissolved in hot xylene and titrated with a KOH-ethanol standard solution to calculate the anhydride content. For glycidyl methacrylate grafted products, the grafting rate was determined by acid-base back titration. Specifically, the quantitative ring-opening addition reaction between epoxy groups and hydrogen halides was utilized, and the content was determined by back titration to calculate the grafting rate. For acrylic acid grafted products, the carboxyl content was determined by acid-base titration. For methyl acrylate grafted products, the grafting rate was determined by acid-base back titration. Specifically, the quantitative reaction between ester groups and strong bases was utilized, and the content was determined by back titration to calculate the grafting rate.

[0032] The number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution (PDI) of post-functionalized polyolefins were determined using high-temperature gel permeation chromatography (HT-GPC) with 1,2,4-trichlorobenzene (TCB) as the eluent, a flow rate of 1.0 ml / min, and a test temperature of 150 °C.

[0033] The melting point of the post-functionalized polyolefin was determined by differential scanning calorimetry (DSC). The DSC curve was recorded as the second heating curve from 30 °C to 200 °C, with a heating rate of 10 °C / min and a cooling rate of 10 °C / min.

[0034] Example 1

[0035] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which is as follows:

[0036] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m 10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of tetrachloroethane. The mixture was heated to 120℃ and stirred until completely dissolved. After the temperature stabilized at 120℃, 0.15 g (0.92 mmol) of NHPI, 0.10 g (0.97 mmol) of TBN, and 1.0 g of MAH were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-MAH. Infrared spectroscopy was performed on the modified PP-g-MAH, and the results showed that at 1780 cm⁻¹... -1 and 1860 cm -1 A distinct characteristic absorption peak of maleic anhydride was observed at the [location missing]. Water contact angle tests were performed on the polymers before and after modification. The results showed that the water contact angle of the unmodified polypropylene (PP) was 102°, while that of the modified PP-g-MAH was 89°. Following the titration method described above, the anhydride grafting rate of the modified PP-g-MAH was determined to be 1.5 mol%. DSC analysis of the modified PP-g-MAH showed that its melting point T [missing value]. m =164.6℃; GPC analysis of the modified PP-g-MAH showed that its weight-average molecular weight M w =296.6 kg / mol, molecular weight distribution PDI=5.3.

[0037] Example 2

[0038] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which is as follows:

[0039] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of tetrachloroethane. The mixture was heated to 100℃ and stirred until completely dissolved. After the temperature stabilized at 100℃, 0.15 g (0.92 mmol) of NHPI, 0.10 g (0.97 mmol) of TBN, and 1.0 g of MAH were added. TBN was added slowly dropwise using a microsyringe, avoiding vigorous boiling and stirring the reaction for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-MAH. Referring to the performance test in Example 1, the water contact angle of the modified PP-g-MAH was determined to be 97°, the maleic anhydride grafting rate was 1.3 mol%, and T m =165.0℃, M w =305.2 kg / mol, PDI=5.2.

[0040] Example 3

[0041] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which is as follows:

[0042] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m 10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of tetrachloroethane. The mixture was heated to 140℃ and stirred until completely dissolved. After the temperature stabilized at 140℃, 0.15 g (0.92 mmol) of NHPI, 0.10 g (0.97 mmol) of TBN, and 1.0 g of MAH were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-MAH. Referring to the performance test in Example 1, the modified PP-g-MAH water contact angle was determined to be 84°, the maleic anhydride grafting rate was 2.1 mol%, and T m =163.9℃, M w =253.2 kg / mol, PDI=5.5.

[0043] Example 4

[0044] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which is as follows:

[0045] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m 10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of tetrachloroethane. The mixture was heated to 120℃ and stirred until completely dissolved. After the temperature stabilized at 120℃, 0.15 g (0.92 mmol) of NHPI, 0.10 g (0.97 mmol) of TBN, and 0.3 g of MAH were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-MAH. Referring to the performance test in Example 1, the modified PP-g-MAH water contact angle was determined to be 94°, the maleic anhydride grafting rate was 0.5 mol%, and T m =164.7℃, M w =302.1 kg / mol, PDI=5.2.

[0046] Example 5

[0047] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which is as follows:

[0048] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of tetrachloroethane. The mixture was heated to 120℃ and stirred until completely dissolved. After the temperature stabilized at 120℃, 0.15 g (0.92 mmol) of NHPI, 0.10 g (0.97 mmol) of TBN, and 2.0 g of MAH were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-MAH. Referring to the performance test in Example 1, the modified PP-g-MAH water contact angle was determined to be 82°, the maleic anhydride grafting rate was 2.3 mol%, and T m =162.9℃, M w =293.1 kg / mol, PDI=5.8.

[0049] Example 6

[0050] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which is as follows:

[0051] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m 10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of xylene. The mixture was heated to 120℃ and stirred until completely dissolved. After the temperature stabilized at 120℃, 0.15 g (0.92 mmol) of NHPI, 0.10 g (0.97 mmol) of TBN, and 1.0 g of MAH were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-MAH. Referring to the performance test in Example 1, the modified PP-g-MAH water contact angle was determined to be 84°, the maleic anhydride grafting rate was 1.8 mol%, and T m =163.9℃, M w =289.1 kg / mol, PDI=5.7.

[0052] Example 7

[0053] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which is as follows:

[0054] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m 10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of xylene. The mixture was heated to 120℃ and stirred until completely dissolved. After the temperature stabilized at 120℃, 0.11 g (0.92 mmol) of N-hydroxysuccinimide (NHS), 0.10 g (0.97 mmol) of TBN, and 1.0 g of MAH were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-MAH. Referring to the performance test in Example 1, the modified PP-g-MAH water contact angle was determined to be 91°, the maleic anhydride grafting rate was 1.2 mol%, and T m =164.3℃, M w =251.4 kg / mol, PDI=5.4.

[0055] Example 8

[0056] This embodiment provides a post-functionalized polyolefin LDPE-g-MAH, the synthesis method of which is as follows:

[0057] Take low-density polyethylene (M w =213.3 kg / mol, PDI=4.9, T m10.0 g of LDPE (at 112.3℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of tetrachloroethane. The mixture was heated to 100℃ and stirred until completely dissolved. After the temperature stabilized at 120℃, 0.20 g (1.23 mmol) of NHPI, 0.13 g (1.26 mmol) of TBN, and 1.2 g of MAH were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 1 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 hours to constant weight to obtain purified LDPE-g-MAH. Referring to the performance test in Example 1, the water contact angle of LDPE before modification was determined to be 98°, and the water contact angle of LDPE-g-MAH after modification was determined to be 84°, with a maleic anhydride grafting rate of 1.7 mol%. T m =112.1℃, M w =200.3 kg / mol, PDI=5.1.

[0058] Example 9

[0059] This embodiment provides a post-functionalized polyolefin HDPE-g-MAH, the synthesis method of which is as follows:

[0060] Take high-density polyethylene (M w =143.2 kg / mol, PDI=8.4, T m 10.0 g of HDPE (at 132.7℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of tetrachloroethane. The mixture was heated to 120℃ and stirred until completely dissolved. After the temperature stabilized at 120℃, 0.12 g (0.74 mmol) of NHPI, 0.08 g (0.78 mmol) of TBN, and 1.0 g of MAH were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 1 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in the precipitation of a white fibrous precipitate. The precipitate was filtered, and the resulting solid was washed three times with acetone and extracted for 12 h using a Soxhlet extractor with acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified HDPE-g-MAH. Referring to the performance test in Example 1, the water contact angle of HDPE before modification was determined to be 96°, and the water contact angle of LDPE-g-MAH after modification was determined to be 82°, with a maleic anhydride grafting rate of 1.3 mol%. T m =132.0℃, M w=139.1 kg / mol, PDI=8.5.

[0061] Example 10

[0062] This embodiment provides a post-functionalized polyolefin PP-g-GMA, the synthesis method of which is as follows:

[0063] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m 10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of tetrachloroethane. The mixture was heated to 120℃ and stirred until completely dissolved. After the temperature stabilized at 120℃, 0.12 g (0.74 mmol) of NHPI, 0.08 g (0.78 mmol) of TBN, and 1.5 g of GMA were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 1 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted GMA and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-GMA. Referring to the performance test in Example 1, the water contact angle of the modified PP-g-GMA was determined to be 86°, the glycidyl methacrylate grafting rate was 0.9 mol%, and the T... m =163.8℃, M w =301.4 kg / mol, PDI=5.3.

[0064] Example 11

[0065] This embodiment provides a post-functionalized polyolefin PP-g-AA, the synthesis method of which is as follows:

[0066] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, and 100 mL of tetrachloroethane was added and stirred until the PP was completely dissolved. After the temperature stabilized at 120℃, 0.15 g (0.92 mmol) of NHPI, 0.1 g (0.97 mmol) of TBN, and 0.8 g of AA were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in the precipitation of a white fibrous precipitate. The precipitate was filtered, and the resulting solid was washed three times with acetone and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted AA and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-AA. Referring to the performance test in Example 1, the modified PP-g-AA water contact angle was determined to be 89°, the acrylic acid grafting rate was 0.8 mol%, and T m =162.9℃, M w =294.1 kg / mol, PDI=5.3.

[0067] Example 12

[0068] This embodiment provides a post-functionalized polyolefin PP-g-MA, the synthesis method of which is as follows:

[0069] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m 10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser. 100 mL of tetrachloroethane was added, and the mixture was heated to 120℃ with stirring until the PP was completely dissolved. After the temperature stabilized at 120℃, 0.15 g (0.92 mmol) of NHPI, 0.1 g (0.97 mmol) of TBN, and 0.9 g of MA were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, and the resulting solid was washed three times with acetone and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MA and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-MA. Referring to the performance test in Example 1, the modified PP-g-MA water contact angle was determined to be 86°, the methyl acrylate grafting rate was 0.8 mol%, and the T... m =162.5℃, M w =295.4 kg / mol, PDI=5.5.

[0070] Example 13

[0071] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which is as follows:

[0072] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m 10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of tetrachloroethane. The mixture was heated to 120℃ and stirred until completely dissolved. After the temperature stabilized at 120℃, 0.10 g (0.61 mmol) of NHPI, 0.15 g (1.45 mmol) of TBN, and 1.0 g of MAH were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-MAH. Referring to the performance test in Example 1, the modified PP-g-MAH water contact angle was determined to be 89°, the maleic anhydride grafting rate was 1.5 mol%, and T m =164.5℃, M w =296.3 kg / mol, PDI=5.4.

[0073] Example 14

[0074] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which is as follows:

[0075] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of tetrachloroethane. The mixture was heated to 120℃ and stirred until completely dissolved. After the temperature stabilized at 120℃, 0.18 g (1.1 mmol) of NHPI, 0.08 g (0.78 mmol) of TBN, and 1.0 g of MAH were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-MAH. Referring to the performance test in Example 1, the modified PP-g-MAH water contact angle was determined to be 91°, the maleic anhydride grafting rate was 1.3 mol%, and T m =163.8℃, M w =294.6 kg / mol, PDI=5.2.

[0076] Example 15

[0077] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which is as follows:

[0078] Take polypropylene (M) w =308.1 kg / mol, PDI=5.2, T m 10.0 g of PP (at 166.4℃) was added to a 250 mL three-necked flask equipped with a reflux condenser, along with 100 mL of tetrachloroethane. The mixture was heated to 120℃ and stirred until completely dissolved. After the temperature stabilized at 120℃, 0.2 g (1.23 mmol) of NHPI, 0.04 g (0.39 mmol) of TBN, and 1.0 g of MAH were added. TBN was added slowly dropwise using a microsyringe to avoid vigorous boiling. The reaction was stirred for 0.5 h. After the reaction was complete, the reaction solution was cooled to 60℃ and slowly poured into 300 mL of acetone, resulting in a white fibrous precipitate. The precipitate was filtered, washed three times with acetone, and extracted for 12 h in a Soxhlet extractor using acetone as the solvent to remove unreacted MAH and NHPI. Finally, the product was dried under vacuum at 60℃ for 24 h to constant weight to obtain purified PP-g-MAH. Referring to the performance test in Example 1, the modified PP-g-MAH water contact angle was determined to be 98°, the maleic anhydride grafting rate was 0.31 mol%, and the T... m =164.2℃, M w =302.8 kg / mol, PDI=5.2.

[0079] Comparative Example 1

[0080] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which differs from Example 1 only in that NHPI is not added, and only 0.10 g TBN is used as the initiator. Everything else remains the same as in Example 1. Referring to the performance test of Example 1, infrared spectroscopy shows that the modified PP-g-MAH has a wavelength of 1780 cm⁻¹. -1 The MAH absorption peak was extremely weak, and the maleic anhydride grafting rate determined by titration was only 0.21 mol%. m =164.4℃, M w =306.3 kg / mol, PDI=5.2. That is, in the absence of NHPI, TBN alone has a limited promoting effect on the grafting reaction, and the grafting rate is extremely low.

[0081] Comparative Example 2

[0082] This embodiment provides a post-functionalized polyolefin PP-g-MAH, the synthesis method of which differs from Example 1 only in that TBN is not added, and only 0.15g NHPI is used as the initiator. Everything else remains the same as in Example 1. Referring to the performance test of Example 1, infrared spectroscopy shows that the modified PP-g-MAH has a wavelength of 1780 cm⁻¹. -1 No obvious MAH absorption peak was observed at T, and titration showed no maleic anhydride grafting. m =164.9℃, M w =307.1 kg / mol, PDI=5.2. That is, in the absence of TBN, NHPI alone has a limited promoting effect on grafting reactions, and MAH is not grafted into the main chain.

[0083] The above embodiments detail the implementation methods and superior effects of the present invention in solution systems. Systematic experimental data demonstrate that the TBN-NHPI / NHS synergistic catalytic system provided by the present invention can achieve efficient grafting modification of polyolefins under mild solution conditions, while effectively maintaining the molecular weight of the matrix. The grafting effect and molecular weight retention rate are significantly better than traditional initiation systems, especially in the TBN-NHPI synergistic catalytic system.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application specification, they can still modify or make equivalent substitutions to the specific implementation of the present invention, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention.

Claims

1. A method for preparing post-functionalized polyolefins using a solution-based co-catalytic process, characterized in that, The preparation steps include the following: Polyolefin, grafted monomer and catalyst are added to an organic solvent, stirred evenly, and heated to react, thereby obtaining the post-functionalized polyolefin. The catalyst is a combination of a first catalyst and a second catalyst; and the first catalyst is selected from tert-butyl nitrite, and the second catalyst is selected from N-hydroxysuccinimide and / or N-hydroxyphthalimide.

2. The method according to claim 1, characterized in that, The polyolefin is selected from at least one of low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, polystyrene, and polyolefin elastomers.

3. The method according to claim 1, characterized in that, The grafting monomer is selected from at least one of maleic anhydride, (meth)acrylic acid, (meth)acrylate, and ethylene.

4. The method according to claim 3, characterized in that, The grafting monomer is selected from at least one of maleic anhydride, (meth)acrylic acid, (meth)acrylate, (meth)methyl methacrylate, (meth)acrylate, (meth)acrylate, (meth)acrylate, glycidyl acrylate, styrene, vinyltrimethoxysilane, and vinyltriethoxysilane.

5. The method according to claim 1, characterized in that, The mass ratio of the polyolefin to the grafted monomer is 100:1~30.

6. The method according to claim 1, characterized in that, The mass ratio of the polyolefin to the tert-butyl nitrite is 100:0.5~10.

7. The method according to claim 1, characterized in that, The molar ratio of the first catalyst to the second catalyst is 1:0.2~5.

8. The method according to claim 1, characterized in that, The organic solvent is selected from at least one of aromatic solvents and halogenated hydrocarbon solvents.

9. The method according to claim 1, characterized in that, The reaction temperature of the heating reaction is 80~140℃; and / or the reaction time of the heating reaction is 0.5~2 h.

10. The method according to claim 1, characterized in that, The heating reaction is followed by steps of precipitating the polymer with a precipitant and / or removing small molecule impurities.

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