A process for the preparation of diethylenetriamine crosslinked liquid polybutadiene rubber

Abstract

A method for preparing diethylenetriamine crosslinked liquid polybutadiene rubber is disclosed. The crosslinked rubber prepared by this invention uses polybutadiene as the main chain and diethylenetriamine as the crosslinking agent. The primary amine groups on the diethylenetriamine molecule react with aldehyde groups to form imine bonds, and the secondary amine groups react with aldehyde groups to form enamines. The preparation process involves: firstly, oxidatively cracking cis-butadiene rubber to prepare aldehyde-terminated polybutadiene; then, adding diethylenetriamine at a mass ratio of 0.03–0.1:1 to the aldehyde-terminated polybutadiene, and preparing the crosslinked rubber using the above reaction. The mixture of diethylenetriamine and aldehyde-terminated polybutadiene can be crosslinked at room temperature, exhibiting low energy consumption and high reactivity, overcoming the problems of complex crosslinking processes or high energy consumption caused by traditional crosslinking rubber using sulfur or peroxides. This rubber possesses self-healing and reusable properties, overcoming the problems of traditional crosslinked rubbers being non-self-healing and non-recyclable.

Description

Technical Field

[0001] This invention relates to a method for preparing diethylenetriamine crosslinked liquid polybutadiene rubber. Background Technology

[0002] Polybutadiene liquid rubber is typically crosslinked using polyisocyanates to prepare crosslinked rubber. After crosslinking, this rubber forms stable covalent bonds, making it unable to self-heal. Therefore, using diethylenetriamine as a crosslinking agent to prepare self-healing and recyclable crosslinked polybutadiene rubber shows great promise for future applications.

[0003] Polybutadiene liquid rubber has aldehyde groups at the ends of its molecular chains, and its main molecular chain has a highly cis structure. Using diethylenetriamine as a crosslinking agent, its primary and secondary amines react chemically with the aldehyde groups on the polybutadiene molecules at room temperature, causing the liquid rubber to crosslink and form a solid. The polybutadiene rubber crosslinked with diethylenetriamine contains dynamic imine and enamine bonds in its main molecular chain. The resulting crosslinked network not only possesses the mechanical properties and stability of traditional crosslinked rubber but also exhibits the self-healing ability of the imine and enamine bonds and the ability to reform into a film after hot pressing following damage. This allows for resource recycling and reuse, demonstrating promising application prospects. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing diethylenetriamine crosslinked liquid polybutadiene rubber at room temperature, so as to solve the problems of high energy consumption, complex process and difficulty in self-repair and recycling of traditional crosslinked rubber preparation.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a cross-linked polybutadiene rubber, wherein the cross-linked polybutadiene rubber is obtained from diethylenetriamine cross-linked aldehyde-terminated polybutadiene.

[0006] Furthermore, the aldehyde-terminated polybutadiene is prepared from cis-butadiene rubber through oxidative pyrolysis.

[0007] A method for preparing diethylenetriamine crosslinked polybutadiene rubber includes the following preparation steps:

[0008] (1) Butadiene rubber was dissolved in a mixed solution of cyclohexane and tetrahydrofuran, and 3-chloroperoxybenzoic acid and periodic acid were added dropwise in sequence to oxidize and pyrolyze the butadiene rubber to prepare liquid aldehyde-terminated polybutadiene.

[0009] (2) After the solvent was removed by rotary evaporation, the aldehyde-terminated polybutadiene solution was washed with ethanol to remove impurities.

[0010] (3) Dissolve aldehyde-terminated polybutadiene in tetrahydrofuran, add diethylenetriamine to the tetrahydrofuran solution of aldehyde-terminated polybutadiene, and stir at room temperature;

[0011] (4) Pour the stirred solution into a polytetrafluoroethylene mold, and obtain cross-linked polybutadiene rubber after the solvent evaporates;

[0012] (5) Place the cross-linked polybutadiene rubber in a vacuum oven until it reaches constant weight.

[0013] Furthermore, in step (1), the concentration of the butadiene rubber solution is 0.05-0.1 g / ml, and the ratio of cyclohexane to tetrahydrofuran in the butadiene rubber solution is 1:1 by volume.

[0014] Furthermore, in step (3), the mass ratio of diethylenetriamine to aldehyde-terminated polybutadiene is 0.03 to 0.1:1.

[0015] Furthermore, the feature is that in step (3), diethylenetriamine is used as a crosslinking agent to crosslink aldehyde-terminated polybutadiene through the reaction of aldehyde and amine groups to prepare polybutadiene crosslinking.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] First, the cross-linked polybutadiene rubber prepared by this invention has an extremely low glass transition temperature and exhibits low-temperature stability. The raw material for preparing the aldehyde-terminated polybutadiene of this invention is cis-butadiene rubber, which retains an extremely low glass transition temperature even after pyrolysis.

[0018] Secondly, the cross-linked polybutadiene rubber prepared by this invention has good fatigue resistance. After being stretched to 100% of the length of the material itself and cyclically stretched 10 times, the elastic recovery rate can still maintain 92.4%, which shows a certain degree of stability.

[0019] Third, the cross-linked polybutadiene rubber prepared by cross-linking diethylenetriamine with aldehyde-terminated polybutadiene exhibits certain self-healing properties and can be recycled and reused. Using diethylenetriamine and aldehyde-terminated polybutadiene as reactants, a cross-linked polybutadiene rubber containing dynamic imine bonds and dynamic enamine bonds was synthesized. This polymer cross-linking network containing dynamic imine and enamine bonds not only preserves the mechanical properties and stability of traditional cross-linking networks but also utilizes dynamic bonds to achieve self-healing and reprocessing of the material.

[0020] Fourth, the cross-linked polybutadiene rubber prepared by this invention has high reactivity. After mixing the cross-linking agent diethylenetriamine with aldehyde-terminated polybutadiene, it can react rapidly at room temperature. The diethylenetriamine and aldehyde-terminated polybutadiene can be stored separately and mixed together for use as a temporary repair agent for plastic and rubber pipes. Attached Figure Description

[0021] Figure 1 The Fourier transform infrared spectrum of the diethylenetriamine crosslinked polybutadiene rubber prepared in this invention is shown.

[0022] Figure 2 The DSC curves of the diethylenetriamine crosslinked polybutadiene rubber prepared in this invention are shown at -150 to 20°C.

[0023] Figure 3 The stress-strain diagram is shown for the diethylenetriamine crosslinked polybutadiene rubber prepared according to the present invention.

[0024] Figure 4 Cyclic tensile curve of the diethylenetriamine crosslinked polybutadiene rubber prepared in this invention.

[0025] Figure 5 These are microscopic images of the diethylenetriamine crosslinked polybutadiene rubber prepared according to this invention before and after self-healing.

[0026] Figure 6 Image showing the recycling of diethylenetriamine crosslinked polybutadiene rubber prepared according to this invention after hot pressing.

[0027] Figure 7 The image shows the contact angle of the diethylenetriamine crosslinked polybutadiene rubber prepared according to the present invention. Detailed Implementation

[0028] Example 1

[0029] A method for preparing diethylenetriamine crosslinked polybutadiene rubber, comprising the following steps:

[0030] (1) In a three-necked flask with a magnetic stirrer, add 5g of cis-butadiene rubber, 50ml of tetrahydrofuran, and 50ml of cyclohexane;

[0031] (2) Weigh 0.1952 g of 3-chloroperoxybenzoic acid and dissolve it in 10 mL of tetrahydrofuran. Slowly add the solution to cis-butadiene rubber. After the addition is complete, continue the reaction for 2 h to obtain an epoxidized polybutadiene solution.

[0032] (3) Weigh 0.2214g of periodic acid and dissolve it in 10ml of tetrahydrofuran. Slowly add it dropwise to the epoxidized polybutadiene solution. After the addition is complete, continue the reaction for 2h to obtain the aldehyde-terminated polybutadiene solution. Add 0.1615g of sodium bicarbonate and let it stand overnight.

[0033] (4) Remove the solvent from the end-aldehyde polybutadiene solution by rotary evaporation, and wash the end-aldehyde polybutadiene with ethanol to remove impurities;

[0034] (5) In another three-necked flask equipped with a magnetic stirrer, add the purified aldehyde-terminated polybutadiene and 50 mL of tetrahydrofuran, then slowly add 0.099 g of diethylenetriamine and continue stirring for 4 h.

[0035] (6) Pour the reacted diethylenetriamine-terminated aldehyde polybutadiene into a polytetrafluoroethylene mold, and obtain cross-linked polybutadiene rubber after the solvent evaporates.

[0036] Example 2

[0037] A method for preparing diethylenetriamine crosslinked polybutadiene rubber, comprising the following steps:

[0038] (1) In a three-necked flask with a magnetic stirrer, add 5g of cis-butadiene rubber, 50ml of tetrahydrofuran, and 50ml of cyclohexane;

[0039] (2) Weigh 0.3904 g of 3-chloroperoxybenzoic acid and dissolve it in 20 mL of tetrahydrofuran. Slowly add the solution to the cis-butadiene rubber solution. After the addition is complete, continue the reaction for 2 h to obtain an epoxidized polybutadiene solution.

[0040] (3) Weigh 0.4428g of periodic acid and dissolve it in 20ml of tetrahydrofuran. Slowly add it dropwise to the epoxidized polybutadiene solution. After the addition is complete, continue the reaction for 2h to obtain an aldehyde-terminated polybutadiene solution. Add 0.323g of sodium bicarbonate and let it stand overnight.

[0041] (4) Remove the solvent from the end-aldehyde polybutadiene solution by rotary evaporation, and wash the end-aldehyde polybutadiene with ethanol to remove impurities;

[0042] (5) In another three-necked flask equipped with a magnetic stirrer, add the purified aldehyde-terminated polybutadiene and 50 mL of tetrahydrofuran, then slowly add 0.198 g of diethylenetriamine and continue stirring for 4 h.

[0043] (6) Pour the reacted diethylenetriamine-terminated aldehyde polybutadiene into a polytetrafluoroethylene mold, and obtain cross-linked polybutadiene rubber after the solvent evaporates.

[0044] Example 3

[0045] A method for preparing diethylenetriamine crosslinked polybutadiene rubber, comprising the following steps:

[0046] (1) In a three-necked flask with a magnetic stirrer, add 5g of cis-butadiene rubber, 50ml of tetrahydrofuran, and 50ml of cyclohexane;

[0047] (2) Weigh 0.5736 g of 3-chloroperoxybenzoic acid and dissolve it in 20 mL of tetrahydrofuran. Slowly add the solution to cis-butadiene rubber. After the addition is complete, continue the reaction for 2 h to obtain an epoxidized polybutadiene solution.

[0048] (3) Weigh 0.6642g of periodic acid and dissolve it in 20ml of tetrahydrofuran. Slowly add it dropwise to the epoxidized polybutadiene solution. After the addition is complete, continue the reaction for 2h to obtain the aldehyde-terminated polybutadiene solution. Add 0.323g of sodium bicarbonate and let it stand overnight.

[0049] (4) Remove the solvent from the end-aldehyde polybutadiene solution by rotary evaporation, and wash the end-aldehyde polybutadiene with ethanol to remove impurities;

[0050] (5) In another three-necked flask equipped with a magnetic stirrer, add the purified aldehyde-terminated polybutadiene and 50 mL of tetrahydrofuran, then slowly add 0.198 g of diethylenetriamine and continue stirring for 4 h.

[0051] (6) Pour the reacted diethylenetriamine-terminated aldehyde polybutadiene into a polytetrafluoroethylene mold, and obtain cross-linked polybutadiene rubber after the solvent evaporates.

[0052] Example 4

[0053] A method for preparing diethylenetriamine crosslinked polybutadiene rubber, comprising the following steps:

[0054] (1) In a three-necked flask with a magnetic stirrer, add 5g of cis-butadiene rubber, 50ml of tetrahydrofuran, and 50ml of cyclohexane;

[0055] (2) Weigh 0.1952 g of 3-chloroperoxybenzoic acid and dissolve it in 10 mL of tetrahydrofuran. Slowly add the solution to cis-butadiene rubber. After the addition is complete, continue the reaction for 2 h to obtain an epoxidized polybutadiene solution.

[0056] (3) Weigh 0.2214g of periodic acid and dissolve it in 10ml of tetrahydrofuran. Slowly add it dropwise to the epoxidized polybutadiene solution. After the addition is complete, continue the reaction for 2h to obtain the aldehyde-terminated polybutadiene solution. Add 0.1615g of sodium bicarbonate and let it stand overnight.

[0057] (4) Remove the solvent from the end-aldehyde polybutadiene solution by rotary evaporation, and wash the end-aldehyde polybutadiene with ethanol to remove impurities;

[0058] (5) In another three-necked flask equipped with a magnetic stirrer, add the purified aldehyde-terminated polybutadiene and 50 mL of toluene, then slowly add 0.099 g of diethylenetriamine and continue stirring for 4 h.

[0059] (6) Pour the reacted diethylenetriamine-terminated aldehyde polybutadiene into a polytetrafluoroethylene mold, and obtain cross-linked polybutadiene rubber after the solvent evaporates.

[0060] Example 5

[0061] A method for preparing diethylenetriamine crosslinked polybutadiene rubber, comprising the following steps:

[0062] (1) In a three-necked flask with a magnetic stirrer, add 5g of cis-butadiene rubber, 50ml of tetrahydrofuran, and 50ml of cyclohexane;

[0063] (2) Weigh 0.1952 g of 3-chloroperoxybenzoic acid and dissolve it in 10 mL of tetrahydrofuran. Slowly add the solution to cis-butadiene rubber. After the addition is complete, continue the reaction for 2 h to obtain an epoxidized polybutadiene solution.

[0064] (3) Weigh 0.2214g of periodic acid and dissolve it in 10ml of tetrahydrofuran. Slowly add it dropwise to the epoxidized polybutadiene solution. After the addition is complete, continue the reaction for 2h to obtain the aldehyde-terminated polybutadiene solution. Add 0.1615g of sodium bicarbonate and let it stand overnight.

[0065] (4) Remove the solvent from the end-aldehyde polybutadiene solution by rotary evaporation, and wash the end-aldehyde polybutadiene with ethanol to remove impurities;

[0066] (5) In another three-necked flask equipped with a magnetic stirrer, add the purified aldehyde-terminated polybutadiene and 50 mL of tetrahydrofuran, then slowly add 0.0743 g of diethylenetriamine and continue stirring for 4 h.

[0067] (6) Pour the reacted diethylenetriamine-terminated aldehyde polybutadiene into a polytetrafluoroethylene mold, and obtain cross-linked polybutadiene rubber after the solvent evaporates.

[0068] Example 6

[0069] A method for preparing diethylenetriamine crosslinked polybutadiene rubber, comprising the following steps:

[0070] (1) In a three-necked flask with a magnetic stirrer, add 5g of cis-butadiene rubber, 50ml of tetrahydrofuran, and 50ml of cyclohexane;

[0071] (2) Weigh 0.1952 g of 3-chloroperoxybenzoic acid and dissolve it in 10 mL of tetrahydrofuran. Slowly add the solution to cis-butadiene rubber. After the addition is complete, continue the reaction for 2 h to obtain an epoxidized polybutadiene solution.

[0072] (3) Weigh 0.2214g of periodic acid and dissolve it in 10ml of tetrahydrofuran. Slowly add it dropwise to the epoxidized polybutadiene solution. After the addition is complete, continue the reaction for 2h to obtain the aldehyde-terminated polybutadiene solution. Add 0.1615g of sodium bicarbonate and let it stand overnight.

[0073] (4) Remove the solvent from the end-aldehyde polybutadiene solution by rotary evaporation, and wash the end-aldehyde polybutadiene with ethanol to remove impurities;

[0074] (5) In another three-necked flask with magnetic stirring, add the purified aldehyde-terminated polybutadiene and 0.0743 g of diethylenetriamine, and continue stirring for 20 min to obtain cross-linked polybutadiene rubber.

[0075] The diethylenetriamine crosslinked polybutadiene rubber prepared using the above method was subjected to the following tests:

[0076] Figure 1 The figure shows the Fourier transform infrared spectrum of the diethylenetriamine crosslinked polybutadiene rubber prepared in this invention; the figure also shows the Fourier transform infrared spectrum of the aldehyde-terminated polybutadiene and the crosslinked polybutadiene rubber prepared in Example 1. The aldehyde-terminated polybutadiene has a carbonyl peak at 1737. After the aldehyde-terminated polybutadiene reacts with diethylenetriamine, the crosslinked polybutadiene rubber does not have a carbonyl peak. The crosslinked polybutadiene rubber has a C=N peak at 1604, which proves the formation of imine bonds.

[0077] Figure 2 The figure shows the DSC curves of the diethylenetriamine crosslinked polybutadiene rubber prepared in this invention at -150 to 20°C. The glass transition temperature of the crosslinked polybutadiene rubber prepared in Example 2 is -103°C, which proves that the crosslinked polybutadiene rubber of this invention has good low-temperature performance.

[0078] Figure 3 The figure shows the stress-strain diagram of the diethylenetriamine crosslinked polybutadiene rubber prepared according to the present invention; the figure shows the stress-strain diagram of Example 1, Example 2, and Example 3. As the content of oxidant in the preparation of aldehyde-terminated polybutadiene increases, the elongation at break and tensile strength of the crosslinked polybutadiene rubber will change. The elongation at break of Example 1, Example 2, and Example 3 are 275%, 133%, and 93%, respectively; the tensile strengths of Example 1, Example 2, and Example 3 are 1.56 MPa, 1.30 MPa, and 1.13 MPa, respectively.

[0079] Figure 4 The figure shows the tensile cycle curve of the diethylenetriamine crosslinked polybutadiene rubber of the present invention; the figure shows the change of elastic recovery rate of the crosslinked polybutadiene rubber prepared according to Example 1 after ten tensile cycles. As can be seen from the figure, the elastic recovery rate of the crosslinked polybutadiene rubber prepared according to Example 1 decreased from 94.6% to 92.4% after 10 cycles of tensile stretching. The elastic recovery rate remained relatively stable, which proves that the crosslinked polybutadiene rubber of the present invention has good fatigue resistance.

[0080] Figure 5 These are microscopic images of the diethylenetriamine crosslinked polybutadiene rubber prepared according to the present invention before and after self-healing. As can be seen from the figures, the cut of the crosslinked polybutadiene rubber prepared according to Example 5 basically healed after being placed at room temperature for 2 hours, proving that the crosslinked polybutadiene rubber of the present invention has a certain self-healing ability.

[0081] Figure 6 The image shows the recycling of the diethylenetriamine crosslinked polybutadiene rubber prepared according to the present invention after hot pressing. The crosslinked polybutadiene rubber prepared according to Example 5 was broken by scissors and placed into a mold. It was then hot-pressed at 10 MPa and 100°C for 40 minutes. The crosslinked polybutadiene rubber reformed into a film, proving that the crosslinked polybutadiene rubber of the present invention can be recycled and reused.

[0082] Figure 7 The image shows the contact angle of the diethylenetriamine crosslinked polybutadiene rubber prepared according to the present invention. The contact angle of the crosslinked polybutadiene rubber prepared according to Example 5 with water is 104.57°, which proves that the crosslinked polybutadiene of the present invention is a hydrophobic material.

Claims

1. A method for preparing diethylenetriamine crosslinked liquid polybutadiene rubber, characterized in that... The rubber is prepared from diethylenetriamine crosslinked terminal aldehyde liquid polybutadiene.

2. A method for preparing diethylenetriamine crosslinked liquid polybutadiene rubber, characterized in that... The rubber is synthesized by reacting the aldehyde group of terminal aldehyde polybutadiene with the primary amine of diethylenetriamine to form an imine bond, and reacting with the secondary amine of diethylenetriamine to form an enamine bond. The dynamic imine bond and the dynamic enamine bond work together to synthesize cross-linked polybutadiene.

3. A method for preparing diethylenetriamine crosslinked liquid polybutadiene rubber, characterized in that, The following steps are included: (1) Butadiene rubber was dissolved in a mixed solution of cyclohexane and tetrahydrofuran, and 3-chloroperoxybenzoic acid and periodic acid were added dropwise in sequence to prepare aldehyde-terminated polybutadiene. (2) After the solvent was removed by rotary evaporation, the aldehyde-terminated polybutadiene solution was washed with ethanol to remove impurities. (3) Dissolve aldehyde-terminated polybutadiene in tetrahydrofuran, add diethylenetriamine to the tetrahydrofuran solution of aldehyde-terminated polybutadiene, and stir at room temperature; (4) Pour the stirred solution into a polytetrafluoroethylene mold, and obtain cross-linked polybutadiene rubber after the solvent evaporates; (5) Place the cross-linked polybutadiene (see details) into a vacuum oven until constant weight is achieved; Furthermore, in step (1), the concentration of the butadiene rubber solution is 0.05-0.1 g / ml, and the ratio of cyclohexane to tetrahydrofuran in the butadiene rubber solution is 1:1 by volume. Furthermore, in step (2), the concentration of the terminal aldehyde polybutadiene solution is 0.2–0.4 ml; Furthermore, in step (3), the mass ratio of diethylenetriamine to aldehyde-terminated polybutadiene is 0.03 to 0.1:1; Furthermore, the characteristic is that in step (3), diethylenetriamine is used as a crosslinking agent to crosslink end-aldehyde polybutadiene to prepare crosslinked polybutadiene rubber.

4. The method for preparing a diethylenetriamine crosslinked liquid polybutadiene rubber according to claim 2, characterized in that... In step 3, the mass ratio of diethylenetriamine to aldehyde-terminated polybutadiene is 0.03 to 0.1:1.

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