A method for preparing crosslinked polymers at room temperature

Abstract

The present invention belongs to the field of synthesis of functional polymers, and particularly relates to a method for preparing crosslinked polymers at room temperature. A vinyl monomer and 4-vinyl benzyl compound are subjected to free radical polymerization by an initiator to obtain a polymer with halogen groups. The polymer with halogen groups is added with 1,1,3,3-tetramethylguanidine under a polar solvent such as N,N-dimethylformamide, and stirred at room temperature for more than 1 hour to obtain a crosslinked product. The method of the present invention has simple operation, mild reaction conditions, low energy consumption, strong monomer applicability, and can be used for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the field of synthesis of functional polymers, and particularly relates to a method for preparing cross-linked polymers at room temperature. Background Art

[0002] In many cases, people improve the performance of polymers by cross-linking them. For example, rubber vulcanization is used to exert the high elasticity of rubber, and film cross-linking is used to achieve the purpose of curing, etc. Generally, polymer cross-linking can be divided into two types: physical cross-linking and chemical cross-linking. Those bound by physical forces such as hydrogen bonds and polar bonds are called physical cross-linking, while if the macromolecules are bound by covalent bonds, it is called chemical cross-linking. Commonly used cross-linking techniques include thermal cross-linking and two-component cross-linking. Although they can achieve cross-linking well, they are restricted by construction conditions and large-area painting, etc., making it impossible to effectively industrialize their applications.

[0003] How to achieve cross-linking and study room-temperature cross-linking systems is a research hotspot in this field. Developing reactive polymers that are linear before use and can cross-link themselves during use has become an effective way to improve the comprehensive performance of related functional polymer products, and is also an important means to reduce environmental pollution. Compared with thermal cross-linking and two-component cross-linking polymerization, single-component room-temperature cross-linking polymers have a broader development prospect because they can achieve cross-linking at room temperature without introducing a cross-linking agent. The technical difficulty lies in how to avoid cross-linking during the preparation and storage of products, so that they have sufficient stability and storage period, and can control the cross-linking reaction at room temperature during use, thereby obtaining polymers with different degrees of cross-linking. Summary of the Invention

[0004] The present invention discloses a method for preparing cross-linked polymers at room temperature. A new method for rapidly cross-linking polymers at room temperature with strong monomer applicability, simple construction, and low energy consumption has been studied. Cross-linking is achieved at room temperature to form a polymer with a network structure, which not only expands the scope of use of cross-linked polymers but also has a relatively simple composition, good stability, acid and alkali resistance after cross-linking, and has good prospects for large-scale application. This method is simple and easy to operate, inexpensive, low in energy consumption, strong in monomer adaptability, and wide in application range.

[0005] The method for preparing cross-linked polymers at room temperature according to the present invention is carried out according to the following steps:

[0006] (1) Carry out free radical polymerization of a vinyl monomer and 4-vinyl benzyl chloride with an initiator to obtain a polymer with a halogen group;

[0007] Among them, the vinyl monomer is styrene, methacrylic acid, methyl methacrylate, 1-bromo-4-((4-vinyl benzyl)oxy)benzene, or a copolymer thereof, etc.;

[0008] The molar ratio of the vinyl monomer to 4-vinyl benzyl compound is 100:2 to 5;

[0009] The initiator is azobisisobutyronitrile, and the ratio of the total mass of the vinyl monomer and 4-vinyl benzyl compound to the mass of azobisisobutyronitrile is 100:0.25 to 0.5.

[0010] The temperature of free radical polymerization is 70 °C to 80 °C, and the free radical polymerization reaction time is more than 8 hours.

[0011] The styrene and 4-vinyl benzyl chloride copolymer has the following structural formula:

[0012]

[0013] (2) After the polymer is precipitated and separated out by a precipitant, the polymer is dissolved in a polar solvent and then stirred and reacted with 1,1,3,3-tetramethylguanidine at room temperature for more than 1 hour to obtain a crosslinked polymer.

[0014] If the reaction monomer is styrene or a copolymer of styrene, the precipitant is anhydrous ethanol; if the reaction monomer is methyl methacrylate or its copolymer, the precipitant is petroleum ether.

[0015] The polar solvent is N,N-dimethylformamide (DMF), N-methylpyrrolidone, and its addition amount is 3 to 6 times the mass of the copolymer.

[0016] The molar ratio of 4-vinyl benzyl compound to 1,1,3,3-tetramethylguanidine in the polymer with halogen terminals is 1:4 to 10.

[0017] The reaction formula for synthesizing the crosslinked polymer is as follows:

[0018]

[0019] Room temperature is the environmental temperature in the laboratory, which is 5 °C - 35 °C.

[0020] Advantages of the present invention: The method for preparing the copolymer is simple, inexpensive, applicable to most vinyl monomers, and has a wide application range. There is no need to add an external crosslinking agent, and the reaction is carried out at room temperature under the catalysis of 1,1,3,3-tetramethylguanidine to form a crosslinked polymer. The crosslinking reaction conditions are mild and the operation is simple and easy.

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

[0022] 1. The raw materials for synthesizing the copolymer in the method of the present invention are cheap and easily available, the synthesis conditions are simple, and it is suitable for large-scale industrial production.

[0023] 2. The cross-linked polymer synthesized by the method of the present invention has simple reaction conditions, can be carried out at room temperature, is easy to operate, the reaction system is relatively simple, and has a wide application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Photos before and after the reaction of preparing the cross-linked polymer in Comparative Example 1.

[0025] Figure 2 Photos before and after the reaction of preparing the cross-linked polymer in Comparative Example 2.

[0026] Figure 3 Photos before and after the reaction of preparing the cross-linked polymer in Example 1.

[0027] Figure 4 Photos before and after the reaction of preparing the cross-linked polymer in Example 2.

[0028] Figure 5 Photos before and after the reaction of preparing the cross-linked polymer in Example 3.

[0029] Figure 6 Photos before and after the reaction of preparing the cross-linked polymer in Example 4.

[0030] Figure 7 Photos before and after the reaction of preparing the cross-linked polymer in Example 5.

[0031] Figure 8 Photos before and after the reaction of preparing the cross-linked polymer in Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0032] The following examples are used to further illustrate the technical features of the present invention, but the protection scope of the present invention is not limited to the following examples.

[0033] Comparative Example 1

[0034] Styrene (5.2001 g, 0.05 mol), 4-vinylbenzyl chloride (0.1506 g, 1 mmol) and azobisisobutyronitrile (0.0134 g, 0.25 wt% of the total monomers) were added to a round-bottom flask, reacted at 70 °C for 6 h and then heated to 80 °C for 2 h to end the reaction. Tetrahydrofuran was added for dissolution, precipitated in absolute ethanol, filtered by suction and then placed in a blast drying oven at 60 °C to dry to constant weight to obtain a white solid. The weighed white solid (0.5004 g) and DMF (1.5010 g, 300 wt% of the copolymer) were added to a 10 mL reaction flask, stirred at room temperature for 14 h, and it was observed that the polymer was not cross-linked. Photos of the polymer before and after the reaction are shown in the attached Figure 1 .

[0035] Comparative Example 2

[0036] Methyl methacrylate (5.0005 g, 0.05 mol), 4-vinylbenzyl chloride (0.1503 g, 1 mmol), and azobisisobutyronitrile (0.0129 g, 0.25 wt% of total monomers) were added to a round-bottom flask. After reacting at 70 °C for 6 h, the temperature was then raised to 80 °C and reacted for 2 h to end the reaction. Tetrahydrofuran was added to dissolve, and it was precipitated in petroleum ether. After suction filtration, it was placed in a blast drying oven at 60 °C and dried to constant weight to obtain a white solid. In a 10 mL reaction flask, the weighed white solid (0.3002 g) and DMF (1.8006 g, 600 wt% copolymer) were added, and stirred at room temperature. After 14 h, it was observed that the polymer was not crosslinked. Photographs of the polymer before and after the reaction are shown in the attached Figure 2 。

[0037] Example 1

[0038] Styrene (5.2002 g, 0.05 mol), 4-vinylbenzyl chloride (0.1504 g, 1 mmol), and azobisisobutyronitrile (0.0268 g, 0.5 wt% of total monomers) were added to a round-bottom flask. After reacting at 70 °C for 6 h, the temperature was then raised to 80 °C and reacted for 2 h to end the reaction. Tetrahydrofuran was added to dissolve, and it was precipitated in absolute ethanol. After suction filtration, it was placed in a blast drying oven at 60 °C and dried to constant weight to obtain a white solid. In a 10 mL reaction flask, the weighed white solid (0.5002 g) was dissolved in DMF (1.5001 g, 300 wt% copolymer). After stirring until the white solid was completely dissolved, 1,1,3,3-tetramethylguanidine (0.0459 g, 0.4 mmol) was added, and stirred at room temperature for 17 h. It was observed that the polymer was crosslinked.

[0039] A part of the polymer was dried to constant weight in a vacuum drying oven at 80 °C. The dried crosslinked polymer was weighed (1.0005 g), then placed in a 50 mL glass sample bottle, and 20 mL of deionized water was added. After constant temperature oscillation in a water bath at 25 °C for 12 hours, the deionized water was changed every 12 hours. After soaking for 5 days, the saturated swollen hydrogel was taken out, the surface moisture was blotted dry with filter paper, and weighed (1.2672 g). The saturated swelling ratio of the hydrogel was calculated to be 26.7 g·g -1 。Photographs of the obtained crosslinked polymer before and after the reaction are shown in the attached Figure 3 。

[0040] Example 2

[0041] Methyl methacrylate (5.0007 g, 0.05 mol), 4-vinylbenzyl chloride (0.1501 g, 1 mmol), and azobisisobutyronitrile (0.0258 g, 0.5 wt% of total monomers) were added to a round-bottom flask. After reacting at 70 °C for 6.5 h, the temperature was then raised to 80 °C and reacted for 2 h to end the reaction. Tetrahydrofuran was added to dissolve, and it was precipitated in petroleum ether. After suction filtration, it was placed in a blast drying oven at 60 °C and dried to constant weight to obtain a white solid. In a 10 mL reaction flask, the weighed white solid (0.5004 g) and DMF (3.0010 g, 600 wt% copolymer) were added. After stirring until completely dissolved, 1,1,3,3-tetramethylguanidine (0.1155 g, 1 mmol) was added. After stirring at room temperature for 10 h, polymer crosslinking was observed.

[0042] A portion of the polymer was dried to constant weight in a vacuum drying oven at 80 °C. The dried crosslinked polymer was weighed (1.0002 g), then placed in a 50 mL glass sample bottle, and 20 mL of deionized water was added. After constant temperature oscillation in a water bath at 25 °C for 12 h, the deionized water was changed every 12 h. After soaking for 5 days, the saturated swollen hydrogel was taken out, the surface moisture was blotted dry with filter paper, and it was weighed (1.1981 g). The saturated swelling ratio of the hydrogel was calculated to be 19.8 g·g -1 The photos of the crosslinked polymer before and after the reaction are shown in the attached Figure 4 。

[0043] Example 3

[0044] Styrene (5.2002 g, 0.05 mol), 4-vinylbenzyl chloride (0.1505 g, 1 mmol), and azobisisobutyronitrile (0.0134 g, 0.25 wt% of total monomers) were added to a round-bottom flask. After reacting at 70 °C for 6 h, the temperature was then raised to 80 °C and reacted for 2 h to end the reaction. Tetrahydrofuran was added to dissolve, and it was precipitated in absolute ethanol. After suction filtration, it was placed in a blast drying oven at 60 °C and dried to constant weight to obtain a white solid. In a 10 mL reaction flask, the weighed white solid (0.5006 g) and DMF (1.5006 g, 300 wt% copolymer) were added. After stirring until completely dissolved, 1,1,3,3-tetramethylguanidine (0.0577 g, 0.5 mmol) was added. After stirring at room temperature for 4 h, polymer crosslinking was observed.

[0045] A portion of the polymer was dried to constant weight in a vacuum drying oven at 80 °C. The dried crosslinked polymer was weighed (1.0004 g), then placed in a 50 mL glass sample bottle, and 20 mL of deionized water was added. After constant temperature oscillation in a water bath at 25 °C for 12 h, the deionized water was changed every 12 h. After soaking for 5 days, the saturated swollen hydrogel was taken out, the surface moisture was blotted dry with filter paper, and it was weighed (1.3012 g). The saturated swelling ratio of the hydrogel was calculated to be 30.1 g·g-1 The photos of the obtained cross-linked polymer before and after the reaction are shown in the appendix of the specification. Figure 5 .

[0046] Example 4

[0047] Methyl methacrylate (5.0006 g, 0.05 mol), 4-vinylbenzyl chloride (0.1506 g, 1 mmol), and azobisisobutyronitrile (0.0129 g, 0.25 wt% of the total monomers) were added to a round-bottom flask. After reacting at 70 °C for 6 h, the temperature was then raised to 80 °C and reacted for 2 h to end the reaction. Tetrahydrofuran was added to dissolve, and the solution was precipitated in petroleum ether. After suction filtration, it was placed in a blast drying oven at 60 °C and dried to a constant weight to obtain a white solid. In a 10 mL reaction flask, the weighed white solid (0.5002 g) and DMF (3.0006 g, 600 wt% of the copolymer) were added. After stirring until completely dissolved, 1,1,3,3-tetramethylguanidine (0.0455 g, 0.4 mmol) was added, and the mixture was stirred at room temperature. After 14 h, cross-linking of the polymer was observed.

[0048] A portion of the polymer was dried to a constant weight in a vacuum drying oven at 80 °C. The dried cross-linked polymer was weighed (1.0005 g), then placed in a 50 mL glass sample bottle, and 20 mL of deionized water was added. After constant temperature oscillation in a water bath at 25 °C for 12 h, the deionized water was changed every 12 h. After soaking for 5 days, the saturated swollen hydrogel was taken out, the surface moisture was blotted dry with filter paper, and its weight was measured (1.2533 g). The saturated swelling ratio of the hydrogel was calculated to be 25.3 g·g -1 The photos of the obtained cross-linked polymer before and after the reaction are shown in the appendix of the specification. Figure 6 .

[0049] Example 5

[0050] Styrene (10.4204 g, 0.1 mol), 4-vinylbenzyl chloride (0.3110 g, 2 mmol), methacrylic acid (0.1704 g, 2 mmol), and azobisisobutyronitrile (0.0502 g, 0.5 wt% of the total monomers) were added to a round-bottom flask. After reacting at 70 °C for 6 h, the temperature was then raised to 80 °C and reacted for 2 h to end the reaction. Tetrahydrofuran was added to dissolve, and the solution was precipitated in absolute ethanol. After suction filtration, it was placed in a blast drying oven at 60 °C and dried to a constant weight to obtain a white solid. In a 10 mL reaction flask, the weighed white solid (0.2506 g) and DMF (0.7501 g, 300 wt% of the copolymer) were added. After stirring until completely dissolved, 1,1,3,3-tetramethylguanidine (0.0457 g, 0.4 mmol) was added, and the mixture was stirred at room temperature. After 1 h, cross-linking of the polymer was observed.

[0051] Take a portion of the polymer and dry it to a constant weight in a vacuum oven at 80 °C. Weigh the dried crosslinked polymer (1.0003 g), then place it in a 50 mL glass sample bottle, add 20 mL of deionized water, and keep it in a water bath at 25 °C with constant shaking for 12 hours. Then change the deionized water every 12 hours. After soaking for 5 days, take out the saturated swollen hydrogel, blot the surface moisture with filter paper, and weigh it (1.3631 g). Calculate the saturated swelling ratio of this hydrogel to be 36.3 g·g -1 The photos of the crosslinked polymer before and after the reaction are shown in the attached instructions Figure 7 .

[0052] Example 6

[0053] Add methyl methacrylate (10.0101 g, 0.1 mol), 4-vinylbenzyl chloride (0.3101 g, 2 mmol), methacrylic acid (0.1709 g, 2 mmol) and azobisisobutyronitrile (0.0504 g, 0.5 wt% of total monomers) into a round-bottom flask. React at 70 °C for 6.5 h and then raise the temperature to 80 °C and react for another 2 h to end the reaction. Add tetrahydrofuran to dissolve, precipitate in petroleum ether, filter by suction, and then dry in a blast oven at 60 °C to a constant weight to obtain a white solid. Add the weighed white solid (0.3003 g) and DMF (1.8001 g, 600 wt% of the copolymer) into a 10 mL reaction flask, stir until completely dissolved, then add 1,1,3,3-tetramethylguanidine (0.0342 g, 0.3 mmol), stir at room temperature, and observe the crosslinking of the polymer after 1 h

[0054] Take a portion of the polymer and dry it to a constant weight in a vacuum oven at 80 °C. Weigh the dried crosslinked polymer (1.0004 g), then place it in a 50 mL glass sample bottle, add 20 mL of deionized water, and keep it in a water bath at 25 °C with constant shaking for 12 hours. Then change the deionized water every 12 hours. After soaking for 5 days, take out the saturated swollen hydrogel, blot the surface moisture with filter paper, and weigh it (1.2811 g). Calculate the saturated swelling ratio of this hydrogel to be 28.1 g·g -1 The photos of the crosslinked polymer before and after the reaction are shown in the attached instructions Figure 8 .

[0055] Example 7

[0056] Styrene (10.8012 g, 0.1 mol), 1-bromo-4-((4-vinylbenzyl)oxy)benzene (1.4451 g, 5 mmol), and azobisisobutyronitrile (0.0503 g, 0.5 wt% of total monomers) were added to a round-bottom flask. After reacting at 70 °C for 6 h, the temperature was then raised to 80 °C and reacted for 2 h to end the reaction. Tetrahydrofuran was added to dissolve, and it was precipitated in absolute ethanol. After suction filtration, it was placed in a blast drying oven at 60 °C and dried to a constant weight to obtain a white solid. In a 10 mL reaction flask, the weighed white solid (1.0003 g) and N-methylpyrrolidone (3.0005 g, 300 wt% of copolymer) were added. After stirring until completely dissolved, 1,1,3,3-tetramethylguanidine (0.0571 g, 0.5 mmol) was added, and it was stirred at room temperature. Polymer crosslinking was observed after 1 h.

[0057] A portion of the polymer was dried to a constant weight in a vacuum drying oven at 80 °C. The dried crosslinked polymer was weighed (1.0003 g), then placed in a 50 mL glass sample bottle, and 20 mL of deionized water was added. After constant temperature oscillation in a water bath at 25 °C for 12 h, the deionized water was changed every 12 h. After soaking for 5 days, the saturated swollen hydrogel was taken out, the surface moisture was blotted dry with filter paper, and it was weighed (1.1583 g). The saturated swelling ratio of this hydrogel was calculated to be 15.8 g·g -1 。

[0058] Example 8

[0059] Styrene (5.2002 g, 0.05 mol), 4-vinylbenzyl chloride (0.1505 g, 1 mmol), and azobisisobutyronitrile (0.0134 g, 0.25 wt% of total monomers) were added to a round-bottom flask. After reacting at 70 °C for 6 h, the temperature was then raised to 80 °C and reacted for 2 h to end the reaction. Tetrahydrofuran was added to dissolve, and it was precipitated in absolute ethanol. After suction filtration, it was placed in a blast drying oven at 60 °C and dried to a constant weight to obtain a white solid. In a 10 mL reaction flask, the weighed white solid (0.5006 g) and DMF (1.5006 g, 300 wt% of copolymer) were added. After stirring until completely dissolved, 1,1,3,3-tetramethylguanidine (0.0687 g, 0.6 mmol) was added, and it was stirred at room temperature. Polymer crosslinking was observed after 4 h.

[0060] A portion of the polymer was dried to a constant weight in a vacuum drying oven at 80 °C. The dried crosslinked polymer was weighed (1.0001 g), then placed in a 50 mL glass sample bottle, and 20 mL of deionized water was added. After constant temperature oscillation in a water bath at 25 °C for 12 h, the deionized water was changed every 12 h. After soaking for 5 days, the saturated swollen hydrogel was taken out, the surface moisture was blotted dry with filter paper, and it was weighed (1.2052 g). The saturated swelling ratio of this hydrogel was calculated to be 20.5 g·g -1 。

[0061] Example 9

[0062] Styrene (5.2002 g, 0.05 mol), 4-vinylbenzyl chloride (0.1505 g, 1 mmol), and azobisisobutyronitrile (0.0134 g, 0.25 wt% of total monomers) were added to a round-bottom flask. After reacting at 70 °C for 6 h, the temperature was then raised to 80 °C and reacted for 2 h to end the reaction. Tetrahydrofuran was added to dissolve, and the solution was precipitated in absolute ethanol. After suction filtration, it was placed in a blast drying oven at 60 °C and dried to a constant weight to obtain a white solid. In a 10 mL reaction flask, the weighed white solid (0.5002 g) and DMF (1.5001 g, 300 wt% of the copolymer) were added. After stirring until completely dissolved, 1,1,3,3-tetramethylguanidine (0.0456 g, 0.4 mmol) was added. Polymer crosslinking was observed after stirring at room temperature for 4 h.

[0063] A portion of the polymer was dried to a constant weight in a vacuum drying oven at 80 °C. The dry crosslinked polymer was weighed (1.0001 g), then placed in a 50 mL glass sample bottle, and 20 mL of deionized water was added. After constant temperature oscillation in a water bath at 25 °C for 12 h, the deionized water was changed every 12 h. After soaking for 5 days, the saturated swollen hydrogel was taken out, the surface moisture was blotted dry with filter paper, and it was weighed (1.2332 g). The saturated swelling ratio of the hydrogel was calculated to be 23.3 g·g -1 。

Claims

1. A method for preparing a crosslinked polymer at room temperature, characterized in that: The method steps are as follows: (1) A vinyl monomer and 4-vinylbenzyl compound are subjected to free radical polymerization initiated by an initiator to obtain a polymer with a halogen group; The molar ratio of the vinyl monomer to the 4-vinylbenzyl compound is 100:2 to 5; the 4-vinylbenzyl compound is 4-vinylbenzyl chloride or 1-bromo-4-((4-vinylbenzyl)oxy)benzene; The vinyl monomer is styrene, methacrylic acid, methyl methacrylate or a copolymer thereof; (2) After the polymer is precipitated and separated out by a precipitant, the polymer is dissolved in a polar solvent and then stirred and reacted with 1,1,3,3-tetramethylguanidine at room temperature for more than 1 hour to obtain a crosslinked polymer; The molar ratio of the 4-vinylbenzyl compound to 1,1,3,3-tetramethylguanidine in the polymer with a halogen group is 1:4 to 10.

2. The method for preparing a crosslinked polymer at room temperature according to claim 1, wherein The initiator in step (1) is azobisisobutyronitrile; the mass ratio of the total mass of the vinyl monomer and the 4-vinylbenzyl compound to the mass of azobisisobutyronitrile is 100:0.25 to 0.

5.

3. The method for preparing a crosslinked polymer at room temperature according to claim 1, wherein The temperature of the free radical polymerization in step (1) is 70°C to 80°C, and the free radical polymerization reaction time is more than 8 hours.

4. The method for preparing a crosslinked polymer at room temperature according to claim 1, wherein, The copolymer obtained by polymerizing styrene and 4-vinylbenzyl chloride in step (1) has the following structural formula:

5. The method for preparing a crosslinked polymer at room temperature according to claim 1, characterized in that, The precipitant in step (2) is anhydrous ethanol or petroleum ether, and the polar solvent is N,N-dimethylformamide or N-methylpyrrolidone.

6. The method for preparing a crosslinked polymer at room temperature according to claim 1, wherein, The structural formula of the synthesized crosslinked polymer in step (2) is as follows: wherein, R is R' is

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