A method for preparing porous resin micro-nano materials based on a lignin template method

Abstract

The present invention belongs to the field of polymer compounds and provides a method for preparing porous resin micro-nano materials based on a lignin template method. The present invention uses lignin as a "soft template" to prepare lignin-based phenolic resin nanospheres with a unique hollow mesoporous structure and controllable particle size. The lignin used in the present invention plays multiple roles in the synthesis of nano materials. On the one hand, it can partially replace 3-aminophenol and formaldehyde to undergo a cross-linking reaction to form the resin ball matrix material; on the other hand, lignin can act as a "template" and dissolve out during subsequent ethanol treatment. The preparation method of the present invention is simple and highly practical, and can obtain stable lignin-based phenolic resin micro-nano spheres with controllable particle size. The nano spheres have a unique hollow structure, and there are many pores on their shell walls, which is the first time to obtain such a morphological structure on phenolic resin micro-nano materials.

Description

Technical Field

[0001] The present invention belongs to the field of polymer compounds, and particularly relates to a method for preparing porous resin micro-nano materials based on a lignin template method. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Phenolic resin, as an important chemical material, is widely used in the fields of construction, energy storage, catalysis, and biomedicine. Phenolic resin is a polymer prepared by the polycondensation reaction of phenolic substances and aldehyde substances (such as formaldehyde, acetaldehyde, etc.) under the catalysis of acid or base. Due to the high carbon-hydrogen ratio and the unique aromatic ring rigid skeleton structure of phenolic resin, it has high thermal stability and excellent mechanical properties. Under hydrothermal synthesis conditions, phenolic resin materials can exhibit regular micro-nano scale spherical structures, further expanding their applications.

[0004] In recent years, spherical phenolic resin micro-nano materials have received a great deal of attention due to their excellent chemical stability and high specific surface area. Especially, their surfaces contain a large number of highly active phenolic hydroxyl structures, enabling them to be used in combination with many cutting-edge materials. For example, in recent research on catechol-based phenolic resin, the ortho-phenolic structure can form reversible chelating forces with metal ions, showing great potential in the fields of sewage treatment and biomedicine. However, the average diameter of phenolic resin nano-spheres formed by the combination of commonly used phenolic substances (such as phenol, resorcinol, or catechol) and aldehyde substances in actual production is relatively large, usually ranging from a few micrometers to dozens of micrometers; moreover, whether using phenol, resorcinol, or catechol as reaction monomers for the synthesis of phenolic resin nano-spheres, their raw material costs are too high and the particle size is too large, bringing difficulties to their commercial applications. In addition, regarding the morphology control of resin micro-nano materials, there are few reports, especially the research on their internal pore structures is significantly insufficient. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a method for preparing porous resin micro-nano materials based on a lignin template method. The present invention uses lignin to replace part of 3-aminophenol to synthesize lignin-based phenolic resin micro-nano spheres, effectively reducing the particle size of phenolic resin micro-nano spheres. When the prepared lignin-based phenolic resin nano-spheres exhibit a hollow structure, a large number of hollow mesoporous structures are presented inside their shells.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect of the present invention, a method for preparing porous resin micro-nano materials based on a lignin template method is provided, including:

[0008] Mix 3-aminophenol, lignin, formaldehyde, ammonia water and water evenly, carry out a polycondensation reaction. After the reaction is completed, add anhydrous ethanol and continue the reaction. After the reaction is completed, carry out a curing treatment to obtain lignin-based phenolic resin micro-nano spheres, that is: porous resin micro-nano materials;

[0009] The temperature of the polycondensation reaction is 30°C - 35°C;

[0010] Among them, the lignin accounts for 5% - 40% of the total mass of 3-aminophenol and lignin, that is: the substitution ratio of lignin for 3-aminophenol is 5% - 40%. Preferably, the lignin accounts for 5% of the total mass of 3-aminophenol and lignin. At this ratio, the phenolic resin micro-nano spheres have the best spherical morphology and yield, which is beneficial to the subsequent multifunctional applications of the micro-nano spheres.

[0011] Preferably, the mass ratio of lignin to water is 1 - 8:6×10 3 , to ensure the smooth progress of the reaction.

[0012] In the present invention, 3-aminophenol reacts with formaldehyde to form phenolic resin nano-spheres. In order to make the reaction proceed fully, the present invention also studies the dosage of components such as formaldehyde. Preferably, the volume ratio of formaldehyde to ammonia water is 0.3:0.3 - 0.4.

[0013] If the reaction time is too short, the reaction is incomplete. If the reaction time is too long, the reaction has reached the end point, which will increase energy consumption. Therefore, the present invention studies the reaction time. Preferably, the time of the polycondensation reaction is 30 min - 35 min.

[0014] The present invention uses anhydrous ethanol for pore formation and expansion to achieve the purpose of reducing the particle size of phenolic resin micro-nano spheres. In order to obtain a better particle size, the present invention studies the dosage of anhydrous ethanol. Preferably, the volume ratio of anhydrous ethanol to ammonia water is 120:0.3 - 0.4.

[0015] In order to ensure that anhydrous ethanol can fully carry out pore formation and expansion on phenolic resin micro-nano spheres, the present invention studies the reaction time. Preferably, the time of the continued reaction is 30 min - 35 min.

[0016] The present invention separates the prepared lignin-based phenolic resin micro-nano spheres from the liquid through a curing treatment. Therefore, preferably, the steps of the curing treatment include: centrifugation, washing, and drying.

[0017] More preferably, the washing is carried out by repeatedly rinsing with water and ethanol to effectively remove impurities on the surface of the lignin-based phenolic resin micro-nano spheres.

[0018] Preferably, the average particle size of the prepared porous resin micro-nano material is 90 nm - 350 nm, with a spherical structure.

[0019] Advantages of the present invention

[0020] (1) Lignin is the most abundant renewable aromatic biological resource on earth and has been commercialized as a by-product of bioethanol production and the pulp industry. Lignin has a benzene ring skeleton similar to that of phenolic resin, and at the same time it contains a large number of active functional groups, including phenolic hydroxyl groups, carboxyl groups, aldehydes and methoxy groups. These functional groups enable lignin to be used as a phenolic substitute in the synthesis of phenolic resin. Using it as a raw material for phenolic resin micro-nano materials not only can reduce the resin synthesis cost, has the characteristics of green sustainability and huge output, but also shows reactivity in the synthesis of phenolic resin micro-nano materials. Using it to prepare resin micro-nano spheres meets the requirements of current green production.

[0021] (2) Compared with the phenolic resin micro-nano spheres participated by 3-aminophenol, the present invention uses lignin to replace part of 3-aminophenol. Since the hydrophilicity of lignin can act as a surfactant, it reduces the surface tension of the nano-spheres, thereby reducing the diameter of the nano-spheres, making the structure of the lignin-based phenolic resin nano-spheres more stable, the nano-size smaller, and the specific surface area larger.

[0022] (3) The preparation steps of the present invention are simple and efficient. Only a certain amount of ethanol treatment can dissolve the low-crosslinked core of the lignin-based phenolic resin nano-spheres to form lignin-based phenolic resin nano-spheres with a hollow structure. And the existence of the lignin "soft template" makes there be many pores on the prepared hollow resin micro-nano shell wall.

[0023] (4) The lignin-based phenolic resin micro-nano spheres prepared by the present invention have stable chemical properties and controllable particle size. At the same time, they have a unique hollow structure and there are many pores on their shell walls. This morphological structure is the first synthesis of phenolic resin micro-nano materials. In addition, due to the unique hollow mesoporous structure of the lignin-based phenolic resin micro-nano spheres, it has an ultra-large specific surface area and a unique space effect, making the micro-nano spheres have the potential to be used as candidate materials such as hydrogel / membrane fillers and carbon materials, and then play a role in fields such as catalysts, nano-material additives, and supercapacitors. Brief description of the drawings

[0024] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0025] Figure 1 : Schematic diagram of the mechanism of the present invention.

[0026] Figure 2 : (a) Zeta potential (electrokinetic potential) diagram of lignin-based phenolic resin micro-nano spheres prepared in Examples 1-5, (b) Stability photos of lignin-based phenolic resin micro-nano spheres prepared in Examples 1-5 standing in deionized water at room temperature for 5 hours, (c) Dispersion stability and Tyndall effect of lignin-based phenolic resin micro-nano spheres prepared in Example 2 in solutions with different pH values; among them, 0%, 5%, 10%, 20%, and 40% correspond to lignin-based phenolic resin micro-nano spheres prepared in Examples 1-5 respectively.

[0027] Figure 3 : (a) Real scene diagram of lignin-based phenolic resin micro-nano spheres prepared in Examples 1-5, (b) Energy dispersive spectroscopy (EDS) element mapping image of lignin-based phenolic resin micro-nano spheres prepared in Example 2, where 0%, 5%, 10%, 20%, and 40% correspond to lignin-based phenolic resin micro-nano spheres prepared in Examples 1-5 respectively, C represents carbon element, N represents nitrogen element, O represents oxygen element, and S represents sulfur element.

[0028] Figure 4 : (a)-(e) are scanning electron microscope images of lignin-based phenolic resin micro-nano spheres prepared in Examples 1-5 respectively, (f)-(j) are transmission electron microscope images of lignin-based phenolic resin micro-nano spheres prepared in Examples 1-5 respectively, and (k)-(o) are size distributions of lignin-based phenolic resin micro-nano spheres prepared in Examples 1-5 respectively. Detailed implementation manners

[0029] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0030] The following will further elaborate on the present invention in conjunction with specific examples. It should be noted that the specific examples are interpretations rather than limitations of the present invention.

[0031] Example 1

[0032] Weigh 600 mg of 3-aminophenol. The substitution ratio of lignin for 3-aminophenol is 0%. Add 0.6 mL of 99 wt% formaldehyde solution and 0.6 mL of 25 wt% ammonia water, and mix them well in deionized water (180 mL). Then transfer the mixed solution to a water bath and heat it at 30 °C for 30 min. After that, add 240 mL of absolute ethanol and continue the reaction for 30 min. Finally, centrifuge the reaction solution at a speed of 9500 rpm, repeatedly rinse the centrifuged solid with distilled water and ethanol, and dry it in a vacuum drying oven to obtain lignin-based phenolic resin micro-nano spheres.

[0033] Example 2

[0034] Weigh 570 mg of 3-aminophenol and 30 mg of lignin. The substitution ratio of lignin for 3-aminophenol is 5%. Add 0.6 mL of 99 wt% formaldehyde solution and 0.6 mL of 25 wt% ammonia water, and mix them well in deionized water (180 mL). Then transfer the mixed solution to a water bath and heat it at 30 °C for 30 min. After that, add 240 mL of absolute ethanol and continue the reaction for 30 min. Finally, centrifuge the reaction solution at a speed of 9500 rpm, repeatedly rinse the centrifuged solid with distilled water and ethanol, and dry it in a vacuum drying oven to obtain lignin-based phenolic resin micro-nano spheres.

[0035] Example 3

[0036] Weigh 540 mg of 3-aminophenol and 60 mg of lignin. The substitution ratio of lignin for 3-aminophenol is 10%. Add 0.6 mL of 99 wt% formaldehyde solution and 0.6 mL of 25 wt% ammonia water, and mix them well in deionized water (180 mL). Then transfer the mixed solution to a water bath and heat it at 30 °C for 30 min. After that, add 240 mL of absolute ethanol and continue the reaction for 30 min. Finally, centrifuge the reaction solution at a speed of 9500 rpm, repeatedly rinse the centrifuged solid with distilled water and ethanol, and dry it in a vacuum drying oven to obtain lignin-based phenolic resin micro-nano spheres.

[0037] Example 4

[0038] Weigh 480 mg of 3-aminophenol and 120 mg of lignin. The proportion of lignin substituting 3-aminophenol is 20%. Add 0.6 mL of 99 wt% formaldehyde solution and 0.8 mL of 25 wt% ammonia water, and mix them well in deionized water (180 mL). Then transfer the mixed solution to a water bath and heat it at 35 °C for 35 min. After that, add 240 mL of absolute ethanol and continue the reaction for 35 min. Finally, centrifuge the reaction solution at a speed of 9500 rpm, repeatedly wash the centrifuged solid with distilled water and ethanol, and dry it in a vacuum drying oven to obtain lignin-based phenolic resin micro-nano spheres.

[0039] Example 5

[0040] Weigh 360 mg of 3-aminophenol and 240 mg of lignin. The proportion of lignin substituting 3-aminophenol is 40%. Add 0.6 mL of 99 wt% formaldehyde solution and 0.6 mL of 25 wt% ammonia water, and mix them well in deionized water (180 mL). Then transfer the mixed solution to a water bath and heat it at 30 °C for 30 min. After that, add 240 mL of absolute ethanol and continue the reaction for 30 min. Finally, centrifuge the reaction solution at a speed of 9500 rpm, repeatedly wash the centrifuged solid with distilled water and ethanol, and dry it in a vacuum drying oven to obtain lignin-based phenolic resin micro-nano spheres.

[0041] The morphologies and properties of the lignin-based phenolic resin micro-nano spheres in Examples 1-5 are shown in Table 1:

[0042] Table 1 Morphologies and properties of the lignin-based phenolic resin micro-nano spheres in Examples 1-5

[0043]

[0044] The schematic diagram of the present invention is as shown in Figure 1 and it can be seen from Figures 2 - 4 that the lignin-based phenolic resin micro-nano spheres prepared from 3-aminophenol, lignin and formaldehyde have uniform sizes and good spherical structures.

[0045] From Table 1 and the comparison between f and g in Figure 4 it can be seen that after using lignin to partially substitute 3-aminophenol, there are many pores on the wall of the prepared hollow resin micro-nano shell, the specific surface area and total pore volume are significantly increased, and the particle size of the lignin-based phenolic resin micro-nano spheres is also significantly reduced.

[0046] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing porous resin micro-nano materials based on lignin template method, characterized in that: include: 3-aminophenol, lignin, formaldehyde, ammonia water and water are mixed evenly to carry out polycondensation reaction. After the reaction is completed, anhydrous ethanol is added to continue the reaction. After the reaction is completed, curing treatment is carried out to obtain lignin-based phenolic resin micro-nanospheres, that is, porous resin micro-nanomaterials; Wherein, the lignin accounts for 5%-40% of the total mass of 3-aminophenol and lignin; The temperature of the polycondensation reaction is 30°C-35°C; The porous resin micro-nano material has a hollow structure, and a shell wall thereof has a plurality of pores.

2. The method for preparing porous resin micro-nano materials based on the lignin template method according to claim 1, characterized in that: The mass ratio of lignin to water is 1-8:6×10 3 .

3. The method for preparing porous resin micro-nano materials based on the lignin template method according to claim 1, characterized in that: The volume ratio of the formaldehyde to the ammonia water is 0.3:0.3-0.

4.

4. The method for preparing porous resin micro-nano materials based on lignin template method according to claim 1, characterized in that: The polycondensation reaction time is 30 min-35 min.

5. The method for preparing porous resin micro-nano materials based on lignin template method according to claim 1, characterized in that: The volume ratio of the anhydrous ethanol to the ammonia water is 120:0.3-0.

4.

6. The method for preparing porous resin micro-nano materials based on lignin template method according to claim 1, characterized in that: The time for the continued reaction is 30 min-35 min.

7. The method for preparing porous resin micro-nano materials based on lignin template method according to claim 1, characterized in that: The steps of the solidification treatment include: centrifugation, washing and drying.

8. The method for preparing porous resin micro-nano materials based on lignin template method according to claim 7, characterized in that: The washing is performed by repeatedly rinsing with water and ethanol.

9. The method for preparing porous resin micro-nano materials based on lignin template method according to claim 1, characterized in that: The prepared porous resin micro-nano material has an average particle size of 90nm-350nm and a spherical structure.

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