A polyolefin block copolymer self-repairing material constructed from simple olefins and a preparation method thereof

Abstract

The application discloses a kind of polyolefin block copolymer self-repairing material constructed by simple olefin and preparation method thereof, belong to polyolefin block copolymer and self-repairing material technical field.The application can control the mechanical properties and self-repairing performance of self-repairing material by the combination system of well-matched group 4-6 metal complex catalyst, cocatalyst and chain transfer agent, and adjusting the structure and proportion of each block.The homopolymer segment of high melting point first olefin monomer provides good dimensional stability and mechanical strength for self-repairing material, and the second olefin monomer segment rich in low glass transition temperature provides self-repairing ability for self-repairing material on the basis of greatly increasing the tensile properties and impact resistance of self-repairing material.The obtained self-repairing material has high melting point, adjustable mechanical properties (elongation at break reaches 1000-2000%, elastic recovery rate can reach 68-98%) and good self-repairing performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyolefin block copolymer and self-repairing material, and more particularly to a polyolefin block copolymer self-repairing material constructed from simple olefins and a preparation method thereof. BACKGROUND

[0002] Polymer materials have the characteristics of wide raw material sources, light weight, easy modification and easy processing, and are widely used in scientific technology, national defense construction and various industries of the national economy, and have become indispensable materials in various aspects of modern social life. However, it is inevitable that in the process of processing or use, the material will be affected by heat, mechanical force, chemical corrosion, etc., and cracks will be formed inside or on the surface, which seriously affects the stability, mechanical properties and service life of the material. Traditionally, damaged materials can be repaired by welding, mechanical connection or adhesive bonding technology, which not only takes time and effort, but also is difficult to completely restore the performance of the material. Inspired by the healing of biological wounds, self-repairing materials have emerged as the times require. When damage occurs during use, the material can achieve self-repairing and restore the performance of the material without intervention or with only a little intervention. This not only prolongs the service life of the material and improves safety, but also greatly reduces the maintenance cost of the material, and ultimately realizes efficient use of resources.

[0003] To design self-repairing polymer materials, it is necessary to understand the physical and chemical processes, repair mechanisms and repair conditions involved in the repair process of the material. The physical and chemical processes involved in the repair of polymer materials are represented. According to the self-repairing theory proposed by Wool and O'Connor in J. Appl. Phys. 1981, 52(11), 5953-5963, the physical repair steps of the polymer include: (a) surface rearrangement; (b) surface approach; (c) wetting; (d) diffusion; (e) randomization process. The mutual diffusion of polymer segments at the damaged interface is the premise of the recovery of the damaged polymer material. The diffusion movement of the segments in the polymer gel or viscous liquid with low glass transition temperature can be easily carried out, but in the high molecular bulk material with strong mechanical properties, the movement ability of the segments is generally poor, so self-repairing materials with mechanical strength are very scarce. In addition, the chemical repair process always needs to be combined with the physical repair process, because chemical reaction can only occur when the reactants come into contact with each other. After the reaction groups on both sides of the fracture come into contact with each other through diffusion, the crack is filled with a newly formed chemical network, so that the material restores the original physical and mechanical properties. In this process, the regeneration of the polymer network is the most critical.

[0004] In general, the synthesis process of the polymer material with self-repairing ability is often more complicated, the structure is very complex, and the mechanical properties are poor, which greatly restricts the practical application of self-repairing materials. Polyolefin materials have great advantages due to their widely available and low-cost raw materials, resistance to harsh use conditions (water, seawater, acid, and alkali). At the same time, polyolefin is the largest and most widely used polymer material in the world. Realizing self-repairing of polyolefin materials has great significance for improving resource utilization efficiency, reducing environmental pressure, and promoting sustainable development.

[0005] However, there are few reports on polyolefin self-repairing materials with a single "C-H" structure. This is because the simple chain structure of polyolefin often means greater versatility and environmental adaptability. At the same time, when there is a lack of chemical interaction and functional groups in the chain structure, the self-repairing of the material mainly depends on the movement of the chain segments. In polymer gels or viscous liquids with low glass transition temperature (T g ) of the polymer, the diffusion movement of the chain segments can be easily carried out. However, in polymer materials with strong mechanical properties, the mobility of the chain segments is usually limited, resulting in a significant reduction in self-repairing efficiency and the need for an excessively long repair time. Therefore, it seems impossible to realize self-repairing performance in polyolefin materials with high strength and saturated "C-H" structure. In order to break this inherent cognition, ingenious design is needed. SUMMARY

[0006] The purpose of the present application is to provide a polyolefin block copolymer self-repairing material constructed from simple olefins and a preparation method thereof, in order to solve the problems existing in the prior art and realize the preparation of a new polyolefin block copolymer material with high melting point, adjustable mechanical properties, and good self-repairing characteristics.

[0007] To achieve the above purpose, the present application provides the following solutions:

[0008] One of the technical solutions of the present application: a polyolefin block copolymer self-repairing material constructed from simple olefins is provided, which comprises at least one first block and at least one second block different from the first block; the first block comprises a first repeating unit, and the second block comprises a second repeating unit; the first repeating unit is polymerized from a first olefin monomer, and the second repeating unit is polymerized from a second olefin monomer; the first olefin monomer independently includes ethylene or propylene; and the second olefin monomer independently includes butene.

[0009] Preferably, the structural formula of the polyolefin block copolymer self-repairing material is as follows:

[0010]

[0011] Wherein, x is independently an integer ≥1, y is independently an integer ≥1, z is independently an integer ≥1.

[0012] The second technical solution of the present application provides a preparation method of the polyolefin block copolymer self-repairing material constructed by simple olefins, comprising the following steps:

[0013] Under the condition of no water and no oxygen, the first olefin monomer is introduced into a polymerization reactor containing a group 4-6 metal complex catalyst, a cocatalyst, a chain transfer agent and a solvent to perform a first polymerization reaction, after the first polymerization reaction is completed, the first olefin monomer is stopped, the second olefin monomer is introduced to perform a second polymerization reaction, after the second polymerization reaction is completed, the first polymerization reaction and / or the second polymerization reaction is repeated n times, wherein n is an integer ≥0, to obtain the polyolefin block copolymer self-repairing material;

[0014] The structural formula of the group 4-6 metal complex catalyst is independently:

[0015] Wherein, M is selected from zirconium or hafnium; R1, R2 and R3 are independently selected from hydrogen, halide or C 1-8 alkyl; halide includes F, Cl, Br or I; Carbon Bridge is selected from C 2-4 alkyl, C 4-10 cycloalkyl, O heterocycle, N heterocycle or S heterocycle; G is selected from chlorine, methyl or benzyl.

[0016] The present application can conveniently control the mechanical properties and self-repairing properties of the self-repairing material by matching the combination system of the group 4-6 metal complex catalyst, the cocatalyst and the chain transfer agent, and adjusting the structure and proportion of each block. Among them, the homopolymer segment of the first olefin monomer with high melting point (T m ) provides good dimensional stability and mechanical strength for the self-repairing material, and the low glass transition temperature (T gThe rich-second olefin monomer segment of the application provides self-repairing capability for the self-repairing material on the basis of greatly increasing the tensile property and impact resistance of the self-repairing material. The prepared self-repairing material has high melting point (131.8 DEG C), adjustable mechanical property (elongation at break of 1000-2000% and elastic recovery rate of 68-98%) and good self-repairing property. The self-repairing material is cut off, and the room temperature repair efficiency is greatly improved, and the self-repairing process can be completed in several hours (6h). The prepared self-repairing material has good self-repairing capability under severe conditions such as water, seawater, acid and alkali, and greatly widens the use scene. The application realizes the self-repairing property of polyolefin material, and has very important significance for prolonging the service life and helping sustainable development. In addition, the repair material is prepared by single-kettle reactor intermittent solution method or multi-kettle series reactor continuous solution method, and the preparation method is efficient, controllable, simple and easy to operate, and the raw material price is low, which provides conditions for realizing the wide application of the new polyolefin block copolymer self-repairing material.

[0017] In the complex system of the Group 4-6 metal complex catalyst, the cocatalyst and the chain transfer agent, the Group 4-6 metal complex catalyst has excellent temperature resistance and excellent polymerization capacity for various olefin monomers, plays the role of a catalytic main body, the cocatalyst can activate the catalyst and form an active center, and the chain transfer agent enables the growing molecular chain to transfer between the active center and the chain transfer agent; the Group 4-6 metal complex catalyst, the cocatalyst and the chain transfer agent cooperate with each other to give the polymerization process a "pseudo-living" characteristic, thereby realizing the synthesis of the polyolefin block copolymer.

[0018] Preferably, the polymerization reactions are carried out in the same polymerization reactor or the polymerization reactions are carried out in m polymerization reactors connected in series; wherein, when the first polymerization reaction and the second polymerization reaction are repeated, m = 2n+2; when the first polymerization reaction or the second polymerization reaction is repeated, m = n+2.

[0019] Preferably, the first olefin monomer independently comprises ethylene or propylene; and the second olefin monomer independently comprises butene.

[0020] Preferably, the cocatalyst independently comprises methylaluminoxane, modified methylaluminoxane or tetra(pentafluorophenyl)borate; the chain transfer agent independently comprises trialkylaluminum or dialkylzinc; and the solvent independently is a hydrocarbon compound, the hydrocarbon compound comprising toluene, xylene, chlorobenzene, C 6-18 alkane, C 6-18 cycloalkane or C 6-18 mixed alkane.

[0021] Preferably, the first olefin monomer is introduced in an amount to bring the system pressure to 0.1-5 MPa; the second olefin monomer is introduced in an amount to bring the system pressure to 0.1-5 MPa; and the molar ratio of the Group 4-6 metal complex catalyst, the cocatalyst and the chain transfer agent is independently 1:1-4000:50-800.

[0022] Preferably, the amount of the solvent is enough to ensure that the polymerization can proceed and the mixed solution of the polymerization system has moderate viscosity.

[0023] Preferably, the reaction conditions of the first polymerization and the second polymerization are independently as follows: temperature 25-190℃, time 1-30 min.

[0024] By controlling the temperature, pressure and time of the polymerization, the present application can realize the control of the polymerization activity, the chain structure composition of the polymer and the molecular weight; when the temperature of the polymerization exceeds the upper limit, the catalyst will gradually deactivate due to high temperature; when the temperature is lower than the lower limit, the polymerization activity is too low to obtain sufficient polymer; when the pressure of the polymerization exceeds the upper limit, the viscosity of the system increases, the overall polymerization activity decreases, the insertion of the second monomer becomes difficult, the chain structure is difficult to control, thereby causing the performance of the polymer to decrease; when the pressure is lower than the lower limit, the polymerization activity is too low, the molecular weight decreases and the quality of the polymer is difficult to meet the requirements; when the time of the polymerization exceeds the upper limit, the viscosity of the system is too high to affect the subsequent polymerization and the control of the chain structure; when the time is lower than the lower limit, the molecular weight of the polymer is too low and the mechanical properties are poor.

[0025] The present application has the following technical effects:

[0026] 1. The present application adopts a combined system of a Group 4-6 metal complex catalyst, a cocatalyst and a chain transfer agent with good matching, and through a single-kettle intermittent batchwise feeding or a multi-kettle series polymerization method, a polyolefin block copolymer self-repairing material with high melting point (131.8℃), adjustable mechanical properties (elongation at break 1000-2000%, elastic recovery rate 68-98%) and good self-repairing performance can be obtained. m The homopolymer segment of the first olefin monomer with high melting point (T g ) provides good dimensional stability and mechanical strength for the self-repairing material, and the rich-second olefin monomer segment with low glass transition temperature (T

[0027] 2、The application designs the structure of the polyolefin block copolymer self-repairing material by regulating the catalyst and polymerization method, uses the most common and easily available olefin monomer as the raw material, and endows the polyolefin with the self-repairing property with the simplest "C-H" structure. The obtained polyolefin block copolymer self-repairing material still has good self-repairing ability under harsh conditions such as water, seawater, acid and alkali, and greatly widens the use scene.

[0028] 3、The preparation method disclosed by the application is high-efficiency controllable, simple and easy to implement, and the raw material is low in price, thereby providing conditions for realizing the wide application of the novel self-repairing material. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The high temperature gel chromatogram of polyethylene / butene two-block copolymer in Example 1 and polyethylene in Comparative Example 1;

[0030] Figure 2 The GPC spectrum of polyethylene / butene three-block copolymer in Example 2; 13 C-NMR spectrum;

[0031] Figure 3 The differential scanning calorimetry (DSC) curve of polyethylene / butene three-block copolymer in Example 2;

[0032] Figure 4 The stress-strain curve of polypropylene / butene three-block copolymer after self-repairing at room temperature for 6h after cutting in Example 3;

[0033] Figure 5 The repair process real object diagram of polypropylene / butene three-block copolymer after self-repairing at room temperature for 6h after cutting in Example 3;

[0034] Figure 6 The stress-strain curve of polyethylene / butene three-block copolymer after self-repairing in seawater for 36h after cutting in Example 4;

[0035] Figure 7 The atomic force microscope image of polyethylene / butene five-block copolymer in Example 5;

[0036] Figure 8 The high temperature gel chromatogram of the product obtained in Comparative Example 7. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present application will now be described in detail, which should not be considered as limiting the present application, but rather as a description of certain aspects, features and embodiments of the present application.

[0038] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, for a range of values of, for example, concentration, intensity, or other values, an intermediate value of the range is specifically contemplated as being included in the application. Any smaller range that falls within the broader range is also contemplated. The upper and lower limits of these smaller ranges can independently be included or excluded in the smaller ranges.

[0039] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All patents, patent applications, articles, and publications mentioned herein are incorporated by reference for the disclosure and description contained therein. In case of conflict between the disclosure of the present specification and the disclosure of any of the incorporated reference documents, the present specification will control.

[0040] Many modifications and variations of this application can be made in the light of the above teachings without departing from the spirit and scope thereof, and it is to be understood that all such modifications and variations warrant the patentable subject matter under the patent laws. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only.

[0041] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean inclusion, but not limited to, the listed material or step.

[0042] The raw materials used in the following examples and comparative examples are commercially available unless otherwise specified. Room temperature refers to 20-30°C.

[0043] The Group 4-6 metal complex catalysts used in the following examples and comparative examples were prepared according to the article "Elizabeth T, Kiesewetter, Michael A. Gelvin, and Robert R. Schrock, "Synthesis and Characterization of Group 4-6 Metal Complexes," Inorg. Chem. 1988, 27, 3156-3161. Randoll, Madalyn, Radlauer, Robert M, Waymouth. Stereospecific octahedral group 4 bis(phenolate) ether complexes for olefin polymerization. [J]. Journal of the American Chemical Society, 2010, 132(16): 5566-7. and “Cuthbert E N T, Vittoria A, Cipullo R, et al. Structure-Activity Relationships for Bis(phenolate-ether) Zr / Hf Propene Polymerization Catalysts [J]. European Journal of Inorganic Chemistry, 2020, 2020(6).” and “Budzelaar M B P H M,, Alexander Z. Voskoboynikov Alexander Z. Voskoboynikov Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia More by Alexander Z. Voskoboynikov, et al. The Interplay of Backbone Stiffening and Active Pocket Design in Bis(phenolate-ether) Zr / Hf Propene Polymerization Catalysts [J]. ACS Catalysis, 2023, 13(20): 13151-13155.” provided the method for preparation.

[0044] Example 1

[0045] Under the condition of completely removing water oxygen, a single reactor batch solution method strategy was adopted with xylene as the solvent (200 mL). The zirconium metal complex catalyst A1, modified methylaluminoxane (MMAO-7) and triisobutylaluminum were added into the reactor (to ensure the molar ratio of the zirconium metal complex catalyst A1, modified methylaluminoxane (MMAO-7) and triisobutylaluminum was 1:2000:300), the temperature in the reactor was controlled at 80 ℃, ethylene gas was introduced into the reactor (the amount of introduction was to make the system pressure reach 1 MPa) to carry out the polymerization reaction, the reaction time was 6 min, then the ethylene gas was switched to butene gas (the system pressure was 1.2 MPa after the introduction), and the second stage polymerization reaction was continued, the reaction time was 3 min, and then the reaction liquid obtained after the termination of the reaction was sequentially precipitated in acidic ethanol, filtered and dried to obtain the polyethylene / butene two-block copolymer.

[0046] The structural formula of the zirconium metal complex catalyst A1 is:

[0047]

[0048] The polyethylene / butene two-block copolymer prepared in the embodiment was subjected to high temperature gel chromatography analysis, and the results are shown in Figure 1 From Figure 1 it can be seen that the molecular weight of the block copolymer sample can reach 200 kDa, and the molecular weight distribution is 2.3. 13 The C-NMR spectrum analysis results are shown in Figure 2 From Figure 2 it can be seen that the characteristic peaks of ethylene and butene fragments exist in the prepared product at the same time, which corresponds to the structure of the polyethylene / butene two-block copolymer, indicating that the polyethylene / butene two-block copolymer is successfully synthesized.

[0049] The ethylene:butene molar insertion ratio of the product obtained in Example 1 determined by nuclear magnetic carbon spectrum is 43:57; the melting point is 131.5 ℃, the elongation at break is 1528%, the elastic recovery rate is 75%, and the repair efficiency at 50 ℃ for 36 h is 67%.

[0050] Example 2

[0051] Under the condition of completely removing water oxygen, a three-reactor series continuous solution method strategy was adopted with Isopar E (produced by Exxon Mobil Corporation) as the solvent (300 mL). In the first reactor, hafnium metal complex catalyst A2, methylaluminoxane (MAO) and diethyl zinc were added (to ensure the molar ratio of hafnium metal complex catalyst A2, methylaluminoxane (MAO) and diethyl zinc was 1:4000:100), the temperature in the first reactor was controlled at 150°C, ethylene gas was introduced into the first reactor (the amount introduced was to make the system pressure reach 3.5 MPa) to carry out the first-stage polymerization reaction, the residence time was 10 min; then butene gas was introduced into the second reactor (the amount introduced was to make the system pressure reach 3.5 MPa) to continue the second-stage polymerization reaction, the residence time was 10 min; finally, ethylene gas was introduced into the third reactor (the amount introduced was to make the system pressure reach 3.5 MPa) to carry out the third-stage polymerization, the residence time was 20 min. The reaction liquid obtained after the reaction was terminated was subjected to precipitation in acidic ethanol, filtration and drying in sequence, to obtain the polyethylene / butene triblock copolymer.

[0052] The structural formula of the hafnium metal complex catalyst A2 is:

[0053]

[0054] The DSC curve of the polyethylene / butene triblock copolymer prepared in this example was analyzed, and the results are shown in Figure 3 From Figure 3 it can be seen that the polyethylene / butene triblock copolymer has a high melting point of 131.8°C and a low glass transition temperature of -38.6°C, and such high melting point and low glass transition temperature performance make it have the potential to be used as a self-repairing material.

[0055] The ethylene:butene molar insertion ratio of the product obtained in Example 2 was determined by nuclear magnetic carbon spectrum to be 55:45; the elongation at break was 1634%, the elastic recovery rate was 68%; and the repair efficiency at 70°C for 24 h was 70%.

[0056] Example 3

[0057] Under the condition of completely removing water oxygen, using single reactor intermittent solution method strategy, with n-hexane as solvent (200 mL), zirconium metal complex catalyst A3, tetrakis (pentafluorophenyl) borate and triethyl aluminum were added into the reactor (to ensure the molar ratio of zirconium metal complex catalyst A3, tetrakis (pentafluorophenyl) borate and triethyl aluminum was 1:2.5:100), the temperature in the reactor was controlled at 30 ℃, propylene gas was introduced into the reactor (the amount of introduction was to make the system pressure reach 0.1 MPa) to carry out the first stage of polymerization reaction, the reaction time was 5 min; then the propylene gas was switched to butene gas (the system pressure was 0.2 MPa after the introduction) to continue the second stage of polymerization reaction, the reaction time was 3 min; finally, the butene gas was switched to propylene gas (the system pressure was 0.2 MPa after the introduction) to continue the third stage of polymerization, the reaction time was 2 min. The reaction liquid obtained after the termination of the reaction was sequentially precipitated in acidic ethanol, filtered and dried to obtain the polypropylene / butene triblock copolymer.

[0058] The structural formula of the zirconium metal complex catalyst A3 is as follows:

[0059]

[0060] The stress-strain curves of the original sample bar and the sample bar after room temperature self-repairing of the polypropylene / butene triblock copolymer prepared in this example are shown in Figure 4 The test process is as follows: two polypropylene / butene triblock copolymers prepared in this example were melt pressed under the same conditions to prepare dumbbell-shaped sample bars, one of which was used to test the stress-strain curve of the original sample bar. The other was cut in half with a blade, and then carefully aligned and placed at room temperature for 6 h before testing the stress-strain curve of the sample bar after room temperature self-repairing. It can be seen from Figure 4 that the polypropylene / butene triblock copolymer can complete the self-repairing process at room temperature for 6 h, with a repair efficiency of 98%, showing very excellent room temperature self-repairing performance.

[0061] The actual picture of the repair process of the polypropylene / butene triblock copolymer prepared in this example is shown in Figure 5 It can be seen from Figure 5 that after the completion of the repair process, the traces of the sample cut completely disappeared, directly showing excellent self-repairing ability.

[0062] The molar insertion ratio of propylene to butene of the product obtained in Example 3 was determined by nuclear magnetic carbon spectrum to be 28:72; the melting point was 119.8 ℃, the elongation at break was 1778%, and the elastic recovery rate was 95%.

[0063] Example 4

[0064] Under the condition of completely removing water oxygen, cyclohexane was used as solvent (200 mL) and a single reactor batch solution method strategy was adopted. Hafnium metal complex catalyst A4, triphenyl carbon tetra (pentafluorophenyl) borate and trimethyl aluminum were added into the reactor (to ensure the molar ratio of hafnium metal complex catalyst A4, triphenyl carbon tetra (pentafluorophenyl) borate and trimethyl aluminum was 1:4:400), the temperature in the reactor was controlled at 80 ℃, ethylene gas was introduced into the reactor (the amount of introduction was to make the system pressure reach 0.5 MPa) to carry out the first stage polymerization reaction, the reaction time was 3 min; then the ethylene gas was switched to butene gas (the system pressure after the introduction was 0.7 MPa) to continue the second stage polymerization reaction, the reaction time was 10 min; finally, the butene gas was switched to ethylene gas (the system pressure after the introduction was 1 MPa) to continue the third stage polymerization, the reaction time was 10 min. The reaction liquid obtained after the termination of the reaction was sequentially subjected to precipitation in acidic ethanol, filtration and drying to obtain the polyethylene / butene triblock copolymer.

[0065] The structural formula of the hafnium metal complex catalyst A4 is as follows:

[0066]

[0067] The stress-strain curves of the original sample bar and the sample bar after self-repairing in seawater of the polyethylene / butene triblock copolymer prepared in this example are shown in Figure 6 The test process is as follows: two polyethylene / butene triblock copolymers prepared in this example were melt pressed under the same conditions to prepare dumbbell-shaped sample bars, one of which was used to test the stress-strain curve of the original sample bar. The other was cut in half with a blade, then carefully aligned, and placed in seawater at 60 ℃ for 1 h, and then placed in seawater at 25 ℃ for 36 h, and the stress-strain curve of the sample bar after self-repairing in seawater was tested. It can be seen from Figure 6 that the polyethylene / butene triblock copolymer has good mechanical properties (the elongation at break reaches 1600%) and still has good self-repairing ability in harsh environments such as seawater at 60 ℃ and seawater at 25 ℃, and the repair efficiency reaches 91%.

[0068] The ethylene:butene molar insertion ratio of the product obtained in Example 4 was determined by nuclear magnetic carbon spectrum to be 15:85; the melting point was 129.6 ℃, and the elastic recovery rate was 85%.

[0069] Example 5

[0070] Under conditions of complete removal of water and oxygen, toluene was used as the solvent (200 mL) in a single-reactor batch solution process. Hafnium metal complex catalyst A5, N,N-dimethylaniline tetra(pentafluorophenyl)borate, and triisobutylaluminum were added to the reactor (ensuring a molar ratio of 1:2:200). The reactor temperature was controlled at 50°C. Ethylene gas was introduced into the reactor (injection rate sufficient to reach a system pressure of 0.2 MPa) for the first stage of polymerization, with a reaction time of 2 min. The second stage of polymerization involved introducing ethylene gas... The first polymerization stage involved switching to butene gas (system pressure 0.3 MPa after introduction) for 3 min; the second stage involved switching to ethylene gas (system pressure 0.4 MPa after introduction) for 2 min; the third stage involved switching to butene gas (system pressure 0.5 MPa after introduction) for 3 min; and the fourth stage involved switching to butene gas (system pressure 0.6 MPa after introduction) for 12 min. The resulting reaction solution was then sequentially precipitated in acidic ethanol, filtered, and dried to obtain the polyethylene / butene pentablock copolymer.

[0071] The structural formula of hafnium metal complex catalyst A5 is as follows:

[0072]

[0073] The atomic force microscopy (AFM) image of the polyethylene / butene pentablock copolymer prepared in this embodiment is as follows: Figure 7 As shown. From Figure 7 As can be seen, the bright "dendritic" regions are polyethylene crystals, the bright "lamellae" are the polybutene phase, and the dark parts are the random copolymer phase. This indicates that the prepared polyethylene / butene pentablock copolymer contains both crystalline and amorphous regions of polyethylene and polybutene, with the amorphous region being dominant. This demonstrates the successful synthesis of the polyethylene / butene pentablock copolymer. The presence of the random copolymer phase can, on the one hand, act as a low-Tg "soft segment," endowing the material with excellent toughness and high elongation at break; on the other hand, it can improve the material's repair efficiency.

[0074] The product obtained in Example 5 had a molar insertion ratio of ethylene to butene of 12:88 as determined by carbon NMR spectroscopy; a melting point of 128.4°C; an elongation at break of 1978%; and an elastic recovery rate of 97%.

[0075] Comparative Example 1

[0076] Under conditions where water and oxygen were completely removed, self-healing materials were prepared using xylene as a solvent (200 mL) via a single-reactor batch solution method. Zirconium metal complex catalyst A1, modified methylaluminoxane (MMAO-7), and triisobutylaluminum (ensuring a molar ratio of 1:2000:300) were added to the reactor. The reactor temperature was controlled at 80°C. Ethylene gas was introduced into the reactor (increased to achieve a system pressure of 1 MPa) to initiate a polymerization reaction for 6 minutes. After termination of the reaction, the reaction solution was sequentially precipitated in acidic ethanol, filtered, and dried to obtain polyethylene.

[0077] The structural formula of zirconium metal complex catalyst A1 is as follows:

[0078]

[0079] High-temperature gel permeation chromatography was performed on the polyethylene / butene diblock copolymer prepared in Example 1 and the polyethylene prepared in Comparative Example 1. The results are as follows: Figure 1 As shown. From Figure 1 As can be seen, the molecular weight of polyethylene is 130 kDa, with a molecular weight distribution of 2.4, while the molecular weight of the polyethylene / butene diblock copolymer can reach 200 kDa, with a molecular weight distribution of 2.3. The molecular weight of the diblock copolymer is significantly increased compared to the homopolymer, while the molecular weight distribution remains basically unchanged, indicating that the molecular weight of the copolymer can be controlled by the polymerization time and the number of polymerization stages.

[0080] Comparative Example 2

[0081] The difference from Example 1 is that during the second polymerization reaction, ethylene gas is introduced at the original pressure, and the same amount of butene gas as in Example 1 is introduced simultaneously. Otherwise, it is the same as Example 1.

[0082] Performance testing: The molar insertion ratio of ethylene to butene in the product obtained in Comparative Example 2, as determined by carbon NMR spectroscopy, was 55:45; the melting point was 129.3℃; the strength decreased significantly, the elongation at break was 1766%, and the elastic recovery rate was 28%.

[0083] Comparing Example 1 and Comparative Example 2, it can be seen that the simultaneous introduction of ethylene and butene gases in the second stage increases the molar insertion rate of ethylene, but significantly reduces the mechanical properties.

[0084] Comparative Example 3

[0085] The difference from Example 2 is that during the second polymerization reaction, ethylene gas is introduced at the original pressure, and the same amount of butene gas as in Example 2 is introduced simultaneously; otherwise, it is the same as Example 2.

[0086] Performance testing: The molar insertion ratio of ethylene to butene in the product obtained in Comparative Example 3, as determined by carbon NMR, was 62:38; the strength decreased significantly, the elongation at break was 1565%, and the elastic recovery rate was 43%.

[0087] Comparing Example 2 and Comparative Example 3, it can be seen that the simultaneous introduction of ethylene and butene gases in the second stage increases the molar insertion rate of ethylene, but significantly reduces the mechanical properties.

[0088] Comparative Example 4

[0089] The difference from Example 3 is that during the second polymerization reaction, propylene gas and butene gas are introduced simultaneously, and the system pressure is 0.2 MPa after introduction. Otherwise, it is the same as Example 3.

[0090] Performance testing: The molar insertion ratio of propylene to butene in the product obtained in Comparative Example 4, as determined by carbon NMR spectroscopy, was 35:65; the strength decreased significantly, the elongation at break was 1433%, and the elastic recovery rate was 37%.

[0091] Comparing Example 3 and Comparative Example 4, it can be seen that the simultaneous introduction of propylene and butene gases in the second stage increases the molar insertion rate of propylene, but significantly reduces the mechanical properties.

[0092] Comparative Example 5

[0093] The difference from Example 4 is that during the second polymerization reaction, ethylene gas and butene gas are introduced simultaneously, and the system pressure is 0.7 MPa after introduction. Otherwise, it is the same as Example 4.

[0094] Performance testing: The molar insertion ratio of ethylene to butene in the product obtained in Comparative Example 5, as determined by carbon NMR spectroscopy, was 24:76; the strength decreased significantly, the elongation at break was 1268%, and there was almost no elastic recovery.

[0095] Comparing Example 4 and Comparative Example 5, it can be seen that the simultaneous introduction of ethylene and butene gases in the second stage increases the molar insertion rate of ethylene, but significantly reduces the mechanical properties.

[0096] Comparative Example 6

[0097] The difference from Example 5 is that during the second and fourth stage polymerization reactions, ethylene gas and butene gas are introduced simultaneously, and the system pressures after introduction are 0.3 MPa and 0.5 MPa, respectively. Otherwise, it is the same as Example 5.

[0098] Performance testing: The molar insertion ratio of ethylene to butene in the product obtained in Comparative Example 6, as determined by carbon NMR spectroscopy, was 8:92; the strength decreased significantly, the elongation at break was 1421%, and there was almost no elastic recovery. The conclusions are the same as those in Comparative Example 2.

[0099] Comparing Example 5 with Comparative Example 6, it can be seen that the simultaneous introduction of ethylene and butene gases in the second stage increases the molar insertion rate of butene, but significantly reduces the mechanical properties.

[0100] Comparative Example 7

[0101] The difference from Example 1 is that "zirconium metal complex catalyst A1" is replaced with a material with the following structural formula:

[0102] The catalyst is the same as in Example 1.

[0103] The high-temperature gel permeation chromatogram of the product obtained in this comparative example is shown below. Figure 8 As shown.

[0104] Figure 8 This is a high-temperature gel permeation chromatogram of the polymer obtained in Comparative Example 7. (From...) Figure 8 It can be seen that the polymerization activity of this comparative example is very low, only 1 / 5 of that of Example 1. The high-temperature gel permeation chromatography characterization results show a multi-peak distribution with a molecular weight distribution of 5.8, indicating that this catalyst cannot synthesize block copolymers, and the final product is a blend.

[0105] Comparative Example 8

[0106] The difference from Example 1 is that no co-catalyst is added to the catalytic system; otherwise, it is the same as Example 1.

[0107] The results showed that there was no polymerization activity and no polymer could be obtained.

[0108] Comparative Example 9

[0109] The difference from Example 1 is that no chain transfer agent is added to the catalytic system; otherwise, it is the same as Example 1.

[0110] The results showed that the polymerization activity decreased, and the resulting polymer had a wider molecular weight distribution (3.8). Distinct shoulder peaks appeared in the high-temperature gel permeation chromatogram, indicating certain blend characteristics.

[0111] Comparative Example 10

[0112] The difference from Example 1 is that the polymerization temperature of the catalytic system is 190°C, while the rest is the same as in Example 1.

[0113] The results showed that as polymerization activity increased, the molecular weight of the polymer decreased significantly, and the mechanical properties deteriorated.

[0114] Comparative Example 11

[0115] The difference from Example 1 is that the polymerization time of the first polymerization stage is 2 minutes and the polymerization time of the second polymerization stage is 8 minutes.

[0116] The results showed that the molar insertion ratio of ethylene to butene in the product obtained in Comparative Example 11 was 23:77; the strength decreased, the elongation at break was 1795%, the elastic recovery rate was 89%, and the self-healing efficiency was 92%. This indicates that the mechanical properties and self-healing properties of the copolymer can be controlled by adjusting the polymerization time at each stage.

[0117] Comparative Example 12

[0118] The difference from Example 1 is that the flow rates of ethylene gas and butene gas were adjusted to ensure that the pressure of the catalytic system was 8 MPa; otherwise, the process was the same as in Example 1.

[0119] The results showed that due to excessively high reaction pressure, the viscosity of the system increased, the copolymerization activity decreased, and the ability to adjust the polymer chain structure declined, resulting in a deterioration in the overall performance of the obtained polyolefin block copolymer.

[0120] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0121] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A self-healing material of polyolefin block copolymers constructed from simple olefins, characterized in that, The polyolefin block copolymer self-healing material comprises at least one first block and at least one second block different from the first block; the first block comprises a first repeating unit, and the second block comprises a second repeating unit; the first repeating unit is polymerized from a first olefin monomer, and the second repeating unit is polymerized from a second olefin monomer; the first olefin monomer is independently ethylene or propylene; the second olefin monomer is independently butene. The first block provides good dimensional stability and mechanical strength for the self-healing material, while the second block provides self-healing capability by increasing the tensile and impact resistance of the self-healing material. The preparation steps of the self-healing polyolefin block copolymer material constructed from simple olefins are as follows: Under anhydrous and oxygen-free conditions, the first olefin monomer is introduced into a polymerization reactor containing a group 4-6 metal complex catalyst, a co-catalyst, a chain transfer agent, and a solvent to carry out a first polymerization reaction. After the first polymerization reaction is completed, the first olefin monomer is stopped, and the second olefin monomer is introduced to carry out a second polymerization reaction. After the second polymerization reaction is completed, the first polymerization reaction and / or the second polymerization reaction are repeated n times, where n is an integer ≥ 0, to obtain the polyolefin block copolymer self-healing material. The structural formulas of the group 4-6 metal complex catalysts are independent as follows: Wherein, M is selected from zirconium or hafnium; R1, R2, and R3 are independently selected from hydrogen, halide, or C. 1-8 Alkyl groups; halogens including F, Cl, Br, or I; Carbon Bridge selected from C 2-4 Alkyl, C 4-10 Cycloalkyl, O-heterocyclic, N-heterocyclic, or S-heterocyclic; G is selected from chloro, methyl, or benzyl; The cocatalyst independently includes methylaluminoxane, modified methylaluminoxane, or tetra(pentafluorophenyl)boride; the chain transfer agent independently includes trialkylaluminum or dialkylzinc; the solvent independently is a hydrocarbon compound, including toluene, xylene, and C. 6-18 Alkanes, C 6-18 Cycloalkanes or C 6-18 Mixed alkanes; The amount of the first olefin monomer introduced is independently such that the system pressure reaches 0.1–5 MPa; the amount of the second olefin monomer introduced is independently such that the system pressure reaches 0.1–5 MPa; the molar ratio of the group 4–6 metal complex catalyst, co-catalyst, and chain transfer agent is independently 1:1–4000:50–800; The reaction conditions for the first polymerization reaction and the second polymerization reaction are independent: temperature 25–190℃, time 1–30 min.

2. The method for preparing the self-healing polyolefin block copolymer material constructed from simple olefins as described in claim 1, characterized in that, Includes the following steps: Under anhydrous and oxygen-free conditions, the first olefin monomer is introduced into a polymerization reactor containing a group 4-6 metal complex catalyst, a co-catalyst, a chain transfer agent, and a solvent to carry out a first polymerization reaction. After the first polymerization reaction is completed, the first olefin monomer is stopped, and the second olefin monomer is introduced to carry out a second polymerization reaction. After the second polymerization reaction is completed, the first polymerization reaction and / or the second polymerization reaction are repeated n times, where n is an integer ≥ 0, to obtain the polyolefin block copolymer self-healing material. The structural formulas of the group 4-6 metal complex catalysts are independent as follows: Wherein, M is selected from zirconium or hafnium; R1, R2, and R3 are independently selected from hydrogen, halide, or C. 1-8 Alkyl groups; halogens including F, Cl, Br, or I; Carbon Bridge selected from C 2-4 Alkyl, C 4-10 Cycloalkyl, O-heterocyclic, N-heterocyclic, or S-heterocyclic; G is selected from chloro, methyl, or benzyl; The first olefin monomer is independently ethylene or propylene; the second olefin monomer is independently butene; The cocatalyst independently includes methylaluminoxane, modified methylaluminoxane, or tetra(pentafluorophenyl)boride; the chain transfer agent independently includes trialkylaluminum or dialkylzinc; the solvent independently is a hydrocarbon compound, including toluene, xylene, and C. 6-18 Alkanes, C 6-18 Cycloalkanes or C 6-18 Mixed alkanes; The amount of the first olefin monomer introduced is independently such that the system pressure reaches 0.1–5 MPa; the amount of the second olefin monomer introduced is independently such that the system pressure reaches 0.1–5 MPa; the molar ratio of the group 4–6 metal complex catalyst, co-catalyst, and chain transfer agent is independently 1:1–4000:50–800; The reaction conditions for the first polymerization reaction and the second polymerization reaction are independent: temperature 25–190℃, time 1–30 min.

3. The method for preparing the self-healing polyolefin block copolymer material constructed from simple olefins according to claim 2, characterized in that, The polymerization reactions are carried out in the same polymerization reactor or in polymerization reactors connected in series.

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