Preparation method of dynamic metal double-coordinate-bond cross-linked ethylene propylene diene monomer rubber
By introducing strong and weak metal coordination bonds into EPDM rubber, the problems of difficult waste rubber recycling and performance imbalance caused by traditional crosslinking methods are solved, and the high mechanical strength and self-healing properties of the material are synergistically improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI UNIV
- Filing Date
- 2025-12-31
- Publication Date
- 2026-04-10
AI Technical Summary
In existing EPDM rubber crosslinking methods, traditional sulfur or peroxide covalent crosslinking methods make it difficult to recycle waste rubber and balance the mechanical properties and self-healing properties of the material.
By introducing strong and weak metal coordination bonds into the rubber system, and by using the reaction of terminal amino-terminated terpyridine with maleic anhydride grafted onto EPDM rubber to form dynamic metal double coordination bonds, a synergistic improvement in mechanical strength and self-healing properties can be achieved.
The prepared EPDM rubber material exhibits excellent flexibility and self-healing properties when the molar ratio of ferrous ions to maleic anhydride is 0.5. The maximum tensile strength is 14.6 MPa, the elongation at break is 800%, the elongation at break recovers to 85% after three remodelings, and the hysteresis loop area recovers to 81% at 50℃.
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Figure CN121825002A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the field of self-repairing materials, and particularly relates to a preparation method of dynamic metal double coordination bond crosslinked ternary ethylene-propylene rubber. BACKGROUND
[0002] Ternary ethylene-propylene rubber (EPDM) rubber is composed of ethylene, propylene and unsaturated diene, and due to its saturated skeleton structure, it exhibits excellent elasticity and flexibility at low temperature, excellent heat resistance, heat-oxygen resistance and ozone aging resistance and other remarkable properties, and is widely used in conveying belts, sealing elements, industrial wires and cables and other fields. However, the main crosslinking method of rubber at present is sulfur or peroxide vulcanization, and the generated irreversible covalent bond brings great difficulty to the recycling of waste rubber.
[0003] Compared with the traditional sulfur or peroxide covalent crosslinking method of rubber, the dynamic reversible crosslinking rubber is adopted, in which the dynamic bond can realize reversible "breakage" and "combination" under certain conditions, realize molecular dynamic exchange and recombination, and endow the material with self-repairing performance and reworkability. According to the type of reversible bond, it can be divided into reversible covalent bond and reversible non-covalent bond. The reversible covalent bond includes disulfide bond, diselenide bond, borate ester bond, DA bond, imine bond and the like, and the reversible non-covalent bond includes hydrogen bond, metal coordination bond, host-guest interaction, π-π interaction and the like. Among them, the metal coordination bond is considered to be one of the strongest supramolecular interactions, and the bond energy is about 50-200 kJ / mol, which is only second to the covalent bond. Due to the numerous optional ligands and metal ions, the thermodynamic stability and kinetic properties of the coordination bond can be flexibly adjusted. Generally, the strength of the coordination site has a great influence on the performance of the synthesized material, and the stronger the coordination site, the higher the mechanical strength of the material will be, but the elongation, self-repairing rate and efficiency will be weakened; the weaker the coordination site, the better the elongation and self-repairing performance will be, but the mechanical strength will be weaker. Based on the metal coordination bond as the self-repairing unit, how to balance the mechanical properties and self-repairing performance of the rubber material is one of the problems to be solved in the field. SUMMARY
[0004] Based on the above technical problems existing in the prior art, the application provides a preparation method of dynamic metal double coordination bond crosslinked ternary ethylene-propylene rubber. By simultaneously introducing strong and weak metal coordination bonds into the rubber system, the strong coordination site provides mechanical strength, and the weak coordination site mainly dissipates energy, so that the enhancement and toughening and good self-repairing performance can be realized.
[0005] The preparation method of the dynamic metal double coordination bond crosslinked ternary ethylene-propylene rubber provided by the application comprises the following steps:
[0006] Maleic anhydride grafted ethylene-propylene-diene rubber and amino-terminated terpyridine are dissolved in a solvent by heating, a water bath reaction is performed, after the reaction is completed, washing and drying in a vacuum oven are performed; then the obtained product is pre-dissolved in a solvent, a ferrous chloride solution is added, stirring is performed for a period of time until uniform dispersion is achieved, then drying in a vacuum oven is performed to allow the solvent to slowly volatilize completely, thereby obtaining a dynamic metal double coordination bond crosslinked ethylene-propylene-diene rubber material.
[0007] The grafting rate of maleic anhydride in the maleic anhydride grafted ethylene-propylene-diene rubber is 0.8 wt%.
[0008] The solvent is tetrahydrofuran.
[0009] The solvent used for washing is ethanol.
[0010] The temperature of the water bath reaction is 60°C, and the reaction time is 6 h.
[0011] The temperature of the vacuum drying is 60°C, and the drying time is 8 h.
[0012] The solvent of the ferrous chloride solution is tetrahydrofuran, the stirring temperature is 60°C, and the time is 30 min.
[0013] The molar ratio of the end amino group of the amino-terminated terpyridine to the maleic anhydride functional group of the maleic anhydride grafted ethylene-propylene-diene rubber is 1:1, and the molar ratio of the end amino group of the amino-terminated terpyridine to the ferrous chloride functional group is 0.25-0.6:1.
[0014] The structural formula of the amino-terminated terpyridine is as follows:
[0015] .
[0016] The amino-terminated terpyridine is prepared by a method comprising the following steps:
[0017] Step 1: 19 mmol of potassium hydroxide is added to 19 mL of dimethyl sulfoxide solution on a 40°C hot table, and a suspension is formed by constant stirring;
[0018] Step 2: 7.3 mmol of ethanolamine is slowly added dropwise to the suspension of Step 1, and stirring is performed until uniform;
[0019] Step 3: Then, 3.7 mmol of 4'-chloro-2,2':6',2''-terpyridine is added, and reaction is performed at 40°C for 4 h, after the reaction is completed, cooling to room temperature is performed;
[0020] Step 4: 60 mL of dichloromethane is added to the system obtained in Step 3, deionized water is further added, the aqueous phase is separated, after multiple washing, drying in a 60°C vacuum oven for 8 h is performed, thereby obtaining the target product.
[0021] The crosslinking structure is shown as follows:
[0022] .
[0023] The application crosslinks rubber through dynamic metal double coordination bonds, designs end-amino trispyridine, and reacts end-amino trispyridine with maleic anhydride-EPDM (EPDM-MAH) based on the reaction of amino and maleic anhydride, and the coordination reaction of trispyridine and carboxyl generated by the reaction with ferrous ions, so that the prepared EPDM has adjustable mechanical strength and different dynamic bond exchange rates by changing the molar ratio of metal ions.
[0024] Compared with the prior art, the beneficial effects of the application are embodied in that:
[0025] The application introduces metal coordination bonds into EPDM and simultaneously introduces two kinds of metal coordination bonds, so that the prepared EPDM has excellent mechanical properties, self-repairing properties and energy dissipation capacity due to the synergistic effect of the two different metal coordination bonds. When the molar ratio of ferrous ions to maleic anhydride is 0.5, the crosslinked EPDM has excellent flexibility and self-repairing properties, the maximum tensile strength is 14.6 MPa, the elongation at break is 800%, the elongation at break can be restored to 85% after 3 times of reshaping, the hysteresis area is the largest, and the hysteresis loop area can be restored to 81% after multiple cycles and 10 s of storage at 50 DEG C.
[0026] The application will be further described in detail below in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS
[0027] Figure 1 The structure formula and nuclear magnetic hydrogen spectrum of end-amino trispyridine ((2-([2,2':6',2''-trispyridine]-4'-oxy)ethylamine) are shown.
[0028] Figure 2 The total reflection infrared spectrum of the rubber sample with different metal ion / maleic anhydride molar ratios obtained in the embodiment of the application is shown.
[0029] Figure 3 The stress-strain curve of the rubber sample with different metal ion / maleic anhydride molar ratios obtained in the embodiment of the application is shown.
[0030] Figure 4 The cyclic stress-strain curve of the rubber sample with different metal ion / maleic anhydride molar ratios obtained in the embodiment of the application is shown.
[0031] Figure 5 The stress-strain curve of the EPTF 0.5 sample obtained in the embodiment of the application after multiple reshaping at 100 DEG C is shown.
[0032] Figure 6 Optical images of crack repair of rubber samples with different metal ion / maleic anhydride molar ratios at the same temperature (80°C) for the same time according to the present application.
[0033] Figure 7 Optical images of crack repair of EPTF 0.5 samples obtained in the embodiments of the present application at different temperatures (60°C, 80°C, 100°C) for the same healing time. DETAILED DESCRIPTION
[0034] The embodiments of the present application are described in detail below, which are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.
[0035] In the following embodiments, the test method of crack repair is as follows: a scalpel is used to draw a crack with a consistent depth on a composite film, and the film is placed on a polarizing microscope for heating repair.
[0036] The method for recycling the remolded material is as follows: the cut pieces of the rubber film are hot-pressed at 100°C and a pressure of 10 MPa for 10 min to re-form a uniform defect-free film, and the mechanical properties thereof are tested.
[0037] Embodiment 1:
[0038] The dynamic metal double coordination bond crosslinked ternary ethylene propylene rubber material is prepared according to the following steps in this embodiment:
[0039] 1. Preparation of terminal amino terpyridine (Tpy-N)
[0040] At 40°C, 1.05 g (19 mmol) of potassium hydroxide was added to 19 mL of dimethyl sulfoxide solution, and a suspension was formed by constant stirring, then 0.41 mL of ethanolamine (7.3 mmol) was slowly added dropwise to the suspension, the suspension was stirred for 20 minutes to make the ethanolamine uniformly distributed, and then 1 g (3.7 mmol) of 4'-chloro-2,2':6',2''-terpyridine was added. After reacting at 40°C for 4 h, the reaction mixture was cooled to room temperature. Then 60 mL of dichloromethane was added, and deionized water was added, the aqueous phase was separated, washed several times, and dried in a vacuum oven at 60°C for 8 h to obtain the target product light yellow solid product (Tpy-N).
[0041] 2. Preparation of crosslinked rubber sample EPTF
[0042] At 60 °C, 10 g of EPDM-g-MAH rubber was pre-dissolved in 100 mL of tetrahydrofuran, and a homogeneous system was formed by constant temperature stirring. Then, 0.25 g (0.87 mmol) of Tpy-N was added, and the reaction was carried out for 6 h under constant temperature stirring. After cooling, 300 mL of ethanol was added for flocculation, and the mixture was filtered and dried in a vacuum oven at 60 °C for 8 h to obtain the ligand-grafted EPT rubber.
[0043] At 60 °C, 1 g of EPT was pre-dissolved in 10 mL of tetrahydrofuran to form a homogeneous solution A. Then, 0.1 g of ferrous chloride was dissolved in 10 mL of tetrahydrofuran to form solution B. According to a molar ratio of terpyridine to ferrous ions of 1:0.25, 0.52 mL of solution B was slowly added to solution A using a constant pressure dropping funnel while magnetic stirring was carried out, and the reaction was carried out for 30 min at 60 °C. The mixed casting solution was slowly poured into a polytetrafluoroethylene plate, and the mixture was left to stand in a vacuum oven at 60 °C for 8 h to dry and remove the solvent, thereby obtaining a metal-ligand crosslinked rubber, which was named EPTF 0.25.
[0044] Example 2:
[0045] In this example, the preparation steps of the crosslinked rubber sample EPTF were the same as those in Example 1, except that:
[0046] At 60 °C, 1 g of EPT was pre-dissolved in 10 mL of tetrahydrofuran to form a homogeneous solution A. Then, 0.1 g of ferrous chloride was dissolved in 10 mL of tetrahydrofuran to form solution B. According to a molar ratio of terpyridine to ferrous ions of 1:0.4, 0.83 mL of solution B was slowly added to solution A using a constant pressure dropping funnel while magnetic stirring was carried out, and the reaction was carried out for 30 min at 60 °C. The mixed casting solution was slowly poured into a polytetrafluoroethylene plate, and the mixture was left to stand in a vacuum oven at 60 °C for 8 h to dry and remove the solvent, thereby obtaining a metal-ligand crosslinked rubber, which was named EPTF 0.4.
[0047] Example 3:
[0048] In this example, the preparation steps of the crosslinked rubber sample EPTF were the same as those in Example 1, except that:
[0049] 1 g EPT was dissolved in 10 mL tetrahydrofuran at 60 °C, after constant temperature stirring to form a homogeneous phase, solution A was prepared, 0.1 g of ferrous chloride was dissolved in 10 mL tetrahydrofuran to prepare solution B, solution B was 1.0 mL according to the molar ratio of terpyridine to ferrous ion 1:0.5, solution B was slowly added to solution A using a constant pressure dropping funnel, magnetic stirring was carried out at the same time, and the reaction was carried out at 60 °C for 30 min. The mixed casting solution was slowly poured into a polytetrafluoroethylene plate, and the solvent was removed by drying in a vacuum oven at 60 °C for 8 h to obtain a metal coordination bond crosslinked rubber, named EPTF 0.5.
[0050] Example 4:
[0051] The preparation steps of the crosslinked rubber sample EPTF in this example are shown in Example 1, and the difference from Example 1 is:
[0052] 1 g EPT was dissolved in 10 mL tetrahydrofuran at 60 °C, after constant temperature stirring to form a homogeneous phase, solution A was prepared, 0.1 g of ferrous chloride was dissolved in 10 mL tetrahydrofuran to prepare solution B, solution B was 1.0 mL according to the molar ratio of terpyridine to ferrous ion 1:0.5, solution B was slowly added to solution A using a constant pressure dropping funnel, magnetic stirring was carried out at the same time, and the reaction was carried out at 60 °C for 30 min. The mixed casting solution was slowly poured into a polytetrafluoroethylene plate, and the solvent was removed by drying in a vacuum oven at 60 °C for 8 h to obtain a metal coordination bond crosslinked rubber, named EPTF 0.5.
[0053] Figure 1 The structure formula and nuclear magnetic hydrogen spectrum of the amino-terminated terpyridine ((2-([2,2':6',2''-terpyridine]-4'-oxy)ethylamine) are shown.
[0054] Figure 2 The crosslinked structure and non-crosslinked structure obtained by Examples 1, 2, 3 and 4 of the application are shown in the full reflection infrared spectrum, from the figure it can be seen that the characteristic absorption peak of the carbon-oxygen-carbon bond of maleic anhydride is 1712 cm -1 , which is weakened, and the characteristic absorption peak of the carbon-nitrogen-carbon bond appears at 1714 cm -1 , and the characteristic absorption peak of the carbon-nitrogen double bond is 1586 cm -1 , and after the formation of the coordination bond, the characteristic absorption peak of the carbon-nitrogen double bond is shifted to 1617 cm -1 .
[0055] Figure 3 The stress-strain curve of the crosslinked rubber sample obtained by Examples 1, 2, 3 and 4 of the application is shown. It can be seen that with the increasing content of ferrous ion, the tensile strength gradually increases, and further increasing the ratio of metal ion / ligand to 0.6 reduces the tensile strength, and Example 3 has the highest tensile strength.
[0056] Figure 4 The cyclic stress-strain curves of the crosslinked rubber samples obtained in examples 1, 2, 3 and 4 of the present application can be seen that after the fifth cycle, the hysteresis loop area is greatly reduced, and the dissipation capacity is reduced, and after being placed at room temperature for 30 min and at 50℃ for 10 s, the hysteresis loop area has different degrees of recovery, and the recovery effect of example 3 is the best.
[0057] Figure 5 The stress-strain curves of the crosslinked rubber sample obtained in example 3 of the present application after multiple remolding at 100℃ can be seen that after 3 times of remolding, the tensile strength can be restored to 70%, and the elongation at break can be restored to 85%.
[0058] Figure 6 The crack repair optical images of the crosslinked rubber samples obtained in examples 1, 2, 3 and 4 of the present application at 80℃ for 10 min can be seen that the samples of the four examples all have good crack repair effect, and the effect of example 3 is the best.
[0059] Figure 7 The optical images of the crack repair of the sample obtained in example 3 of the present application at different temperatures (60℃, 80℃, 100℃) for the same healing time can be seen that as the temperature rises, the exchange rate of dynamic bonds accelerates, and the repair efficiency is higher.
[0060] The above are only exemplary embodiments of the present application and are not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. A method for preparing a metal-coordinated crosslinked EPDM rubber, characterized in that... Includes the following steps: Maleic anhydride-grafted EPDM rubber and terpyridine with terminal amino groups were heated and dissolved in a solvent, and then reacted in a water bath. After the reaction was completed, the product was washed and dried in a vacuum oven. Subsequently, the product was pre-dissolved in a solvent, ferrous chloride solution was added and stirred to disperse it evenly, and then dried in a vacuum oven to allow the solvent to evaporate slowly and completely, thus obtaining a dynamically metal-coordinated crosslinked EPDM rubber material. The structure of the terminal amino group of the terpyridine is shown below: 。 2. The preparation method according to claim 1, characterized in that: The grafting rate of maleic anhydride in the maleic anhydride-grafted EPDM rubber is 0.8 wt%.
3. The preparation method according to claim 1, characterized in that: The solvent is tetrahydrofuran.
4. The preparation method according to claim 1, characterized in that: The water bath reaction was carried out at a temperature of 60℃ for 6 hours.
5. The preparation method according to claim 1, characterized in that: The solvent for the ferrous chloride solution is tetrahydrofuran, and the stirring temperature is 60°C for 30 min.
6. The preparation method according to claim 1, characterized in that: The molar ratio of the terminal amino group of the terpyridine to the maleic anhydride functional group of the maleic anhydride-grafted EPDM rubber is 1:
1.
7. The preparation method according to claim 1, characterized in that: The molar ratio of the terminal amino group to the ferrous chloride functional group in the terpyridine with the terminal amino group is 0.25~0.6:
1.
8. The preparation method according to claim 1, characterized in that... The terpyridine with the terminal amino group is prepared by a method comprising the following steps: Step 1: Add potassium hydroxide to dimethyl sulfoxide solution on a 40 ℃ hot plate and stir continuously to form a suspension; Step 2: Slowly add ethanolamine dropwise to the suspension from Step 1 and stir until homogeneous; Step 3: Then add 4'-chloro-2,2':6',2''-terpyridine and react at 40°C for 4 h. After the reaction is complete, cool to room temperature. Step 4: Add dichloromethane to the system obtained in Step 3, then add deionized water, separate the aqueous phase, wash and vacuum dry to obtain the target product.