Alkoxy covalently modified MXene as well as preparation method and application thereof
By covalently modifying MXene with alkoxy groups, the problems of dispersion and conductivity of MXene in organic solvents are solved, achieving stable dispersion and high conductivity in a variety of solvents, which is suitable for high-precision electrofluid printing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHWEST JIAOTONG UNIV
- Filing Date
- 2025-12-23
- Publication Date
- 2026-05-12
AI Technical Summary
Existing MXene materials exhibit poor dispersibility in organic solvents, and are particularly unstable in non-polar solvents, resulting in decreased conductivity, making it difficult to meet the high precision and high conductivity requirements of electrofluid printing technology.
Modified MXene through alkoxy covalent modification utilizes alkoxy groups as strong nucleophiles to form covalent bonds with metal atoms on the MXene surface, replacing the original -OH groups. This achieves stable dispersion of MXene in both polar and nonpolar organic solvents while maintaining high conductivity.
The modified MXene exhibits excellent amphiphilic dispersibility in a variety of solvents, maintains high conductivity, and is suitable for high-precision electrofluid printing, producing clear electronic components with micron-level linewidths.
Smart Images
Figure CN122011808A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of MXene material technology, specifically to an alkoxy-covalently modified MXene, its preparation method, and its application. Background Technology
[0002] MXenes, as a new class of two-dimensional transition metal carbides, nitrides or carbonitrides, have attracted widespread attention since their discovery in 2011 due to their high metallic conductivity, good mechanical strength and unique optical and thermal properties. They have shown great application potential in energy storage, electromagnetic interference shielding, sensing and transparent conductive films.
[0003] The abundant hydrophilic terminal groups on the surface of MXene enable it to be stably dispersed in aqueous solutions and can be film-formed using solution processing techniques such as spray coating, spin coating, and blade coating. However, the inherent hydrophilicity of MXene also presents two major challenges. First, MXene has poor chemical stability; when dispersed in aqueous solutions or exposed to humid air, it is highly susceptible to oxidative degradation, leading to a rapid decline in its excellent conductivity and other physicochemical properties, significantly shortening the lifespan of devices. Second, its strongly hydrophilic surface has poor compatibility with most organic solvents, especially nonpolar or weakly polar solvents, making it difficult to disperse stably in them. This characteristic severely limits the use of MXene in many industrial applications.
[0004] In the manufacturing processes of many electronic devices, especially when using electrohydraulic printing technology, there are specific requirements for ink solvents: organic solvents with a certain degree of polarity but relatively low surface tension (such as ethanol and toluene) are typically needed to ensure the formation of stable Taylor cones and the achievement of fine jetting under an electric field. Water, due to its high surface tension, high boiling point, and tendency to cause electrode short circuits, is generally unsuitable as a solvent for electrohydraulic printing inks. Because of the instability of perovskites in polar solvents, non-polar solvents such as toluene must be used. Similarly, in the synthesis of general-purpose polymer composites (such as polyurethane and polyimide) for flexible electronic devices, electromagnetic shielding, and energy storage systems, fillers that are well-compatible with these polymer solvents are required, and these solvents are mostly non-polar. Therefore, developing MXene materials that can be stably dispersed in a variety of organic solvents, including non-polar solvents, while maintaining their intrinsic high conductivity has become crucial for their practical application, especially in electrohydraulic printing technology.
[0005] To improve the dispersibility of MXene in organic solvents, researchers have attempted to modify its surface by grafting organic ligands with hydrophobic segments. For example, reported modifiers include polyacrylonitrile fibers, alkylphosphonic acids, polycarboxylic acid ethers, and bis(hydrogenated tallow)benzylmethylammonium chloride. While these modification strategies have improved the dispersibility and antioxidant properties of MXene in organic solvents to some extent, they typically introduce long-chain or large-volume organic molecules. These molecules hinder electron transport between MXene layers and significantly increase the interlayer spacing, leading to a sharp decrease in the conductivity of the modified MXene. This makes it difficult to apply to applications requiring high conductivity, such as printed wires, coils, and electrodes.
[0006] Electrofluid printing, as an emerging micro- and nano-scale patterning manufacturing technology, can precisely control ink droplet deposition through an electric field to achieve high-resolution patterns far exceeding the precision of traditional inkjet printing. However, this technology places extremely high demands on ink performance: the ink needs to possess excellent dispersion stability and suitable rheological properties in specific organic solvents to ensure a smooth and unclogging printing process; simultaneously, the printed patterns must have high electrical conductivity to be directly used in functional electronic devices. Existing MXene materials cannot simultaneously meet these stringent requirements. Therefore, developing an MXene ink that is broadly compatible with organic solvents, maintains high conductivity, and is suitable for electrofluid printing is a pressing technical challenge in this field. Summary of the Invention
[0007] To address the aforementioned technical problems, the present invention aims to provide an alkoxy-covalently modified MXene, its preparation method, and its application. The present invention achieves amphiphilicity in MXene through a simple one-step covalent surface modification, enabling stable dispersion in a variety of polar and non-polar organic solvents, while maximizing the maintenance of high conductivity and improving its applicability in high-precision electrofluid printing.
[0008] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for preparing alkoxy-covalently modified MXene is provided, comprising the following steps: (1) Centrifuge the aqueous dispersion of monolayer MXene, then wash it with an organic solvent, and then disperse it in an organic solvent to obtain an organic dispersion of MXene; (2) Dissolve sodium alkoxy in toluene, then add the MXene organic dispersion obtained in step (1), stir the reaction in an inert gas atmosphere, centrifuge after the reaction is completed, and then wash with hydrochloric acid and ethanol to obtain alkoxy covalently modified MXene.
[0009] Aqueous dispersions of monolayer MXene refer to liquids in which monolayer MXene is dispersed in water, with a typical concentration of approximately 1.9 mg / mL. MXene materials include, but are not limited to, Ti3C2T. x .
[0010] In this invention, during the reaction, alkoxy groups act as strong nucleophiles, covalently grafting onto the metal atoms on the MXene surface via a nucleophilic substitution mechanism, replacing the original -OH and other terminal groups to form stable covalent bonds. After the reaction, the reaction byproduct NaOH is thoroughly removed by repeated centrifugation and washing with hydrochloric acid and ethanol.
[0011] Furthermore, in step (1), the organic solvent is dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF).
[0012] Furthermore, in step (1), the concentration of the MXene organic dispersion is 1-10 mg / mL.
[0013] Furthermore, in step (2), the sodium alkoxy is sodium ethoxide or sodium phenolate.
[0014] Furthermore, in step (2), the mass-to-volume ratio of sodium alkoxy and toluene is 2-20 mg: 1 mL.
[0015] Furthermore, in step (2), the amount of sodium alkoxy is 10-100% of the mass of MXene in the MXene organic dispersion.
[0016] Furthermore, in step (2), the reaction is stirred at 30-50°C for 3-24 h.
[0017] Furthermore, in step (2), washing with methanol can be used instead.
[0018] Furthermore, after the preparation is completed, the alkoxy-covalently modified MXene is dispersed in ethanol for storage. If it needs to be dispersed in other solvents, solvent exchange is performed by centrifugation.
[0019] The present invention also provides a method for preparing the above-mentioned alkoxy-covalently modified MXene, which yields alkoxy-covalently modified MXene.
[0020] This invention also provides the application of the above-mentioned alkoxy covalently modified MXene in the preparation of electrofluid printing inks.
[0021] The present invention also provides a highly conductive ink suitable for electrofluid printing, which is prepared from alkoxy-covalently modified MXene.
[0022] Furthermore, the modified MXene, which is covalently modified with alkoxy groups, is prepared by dispersing it in a solvent at a concentration of 0.4-3.5 mg / mL.
[0023] The present invention has the following beneficial effects: 1. The alkoxy-covalently modified MXene prepared by the method of this invention exhibits excellent amphiphilic dispersibility. Experiments have confirmed that it can form a uniform and stable dispersion in water, polar organic solvents (such as methanol and ethanol), and non-polar organic solvents (toluene), showing no signs of sedimentation even after standing for several days. In contrast, unmodified MXene can only be stably dispersed in water and will rapidly aggregate and settle in most organic solvents. This broad solvent compatibility allows the modified MXene to adapt to the needs of different polymer systems and processing environments, especially meeting the core requirements of electrohydraulic printing for organic solvent-based inks.
[0024] 2. The modified MXene of this invention can be well applied to electrohydraulic printing. When the modified MXene is formulated with suitable organic solvents such as ethanol to prepare conductive inks of different concentrations, it exhibits excellent film-forming properties and conductivity. Using this ink, precise control of the printed linewidth was successfully achieved by adjusting parameters such as voltage (1-3 kV), air pressure (0-1 kPa), printing speed (1-7 mm / s), number of printing layers (1-7 layers), and needle distance (0.3-0.7 mm), and clear bar patterns were printed with linewidths down to the micrometer level. This has great application potential in the fabrication of high-precision, high-conductivity flexible circuits, sensors, antennas, and other electronic components. Attached Figure Description
[0025] Figure 1 This is a diagram showing the dispersion of unmodified MXene in a solvent; Figure 2 This is a diagram showing the dispersion of the modified MXene in the solvent; Figure 3 A comparison of the conductivity retention rates of unmodified and modified MXene films; Figure 4 Printing effect image of modified MXene ink; Figure 5 Printing results of unmodified MXene ink; Figure 6 Example images showing MXene films with different linewidths obtained by printing modified MXene ink. Detailed Implementation
[0026] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.
[0027] Example 1 An alkoxy-covalently modified MXene, the preparation method of which includes the following steps: (1) Single-layer MXene (Ti3C2T) x The aqueous dispersion of MXene was centrifuged at 4000 rpm for 3 min, then washed with N,N-dimethylformamide, and then dispersed in N,N-dimethylformamide to obtain a 5 mg / mL MXene organic dispersion. (2) Sodium ethoxide was dissolved in toluene at a mass-volume ratio of 10 mg: 1 mL. The MXene organic dispersion obtained in step (1) was added. The amount of sodium alkoxy was 50% of the mass of MXene. The mixture was stirred at 40°C for 12 h in an inert gas atmosphere. After the reaction was completed, the mixture was centrifuged and washed with hydrochloric acid and ethanol to obtain alkoxy covalently modified MXene.
[0028] Example 2 An alkoxy-covalently modified MXene, the preparation method of which includes the following steps: (1) Single-layer MXene (Ti3C2T) x The aqueous dispersion of MXene was centrifuged at 4000 rpm for 3 min, then washed with dimethyl sulfoxide, and then dispersed in dimethyl sulfoxide amine to obtain a 1 mg / mL MXene organic dispersion. (2) Sodium ethoxide or sodium phenolate was dissolved in toluene at a mass-volume ratio of 2 mg: 1 mL. The MXene organic dispersion obtained in step (1) was added. The amount of sodium alkoxy was 10% of the mass of MXene. The mixture was stirred at 30°C for 3 h in an inert gas atmosphere. After the reaction was completed, the mixture was centrifuged and washed with methanol to obtain alkoxy covalently modified MXene.
[0029] Example 3 An alkoxy-covalently modified MXene, the preparation method of which includes the following steps: (1) Single-layer MXene (Ti3C2T) x The aqueous dispersion of MXene was centrifuged at 4000 rpm for 3 min, then washed with dimethyl sulfoxide, and then dispersed in dimethyl sulfoxide to obtain a 10 mg / mL MXene organic dispersion. (2) Sodium ethoxide was dissolved in toluene at a mass-volume ratio of 20 mg: 1 mL. The MXene organic dispersion obtained in step (1) was added. The amount of sodium alkoxy was 100% of the mass of MXene. The mixture was stirred at 50°C for 24 h in an inert gas atmosphere. After the reaction was completed, the mixture was centrifuged and washed with hydrochloric acid and ethanol to obtain alkoxy covalently modified MXene.
[0030] Experimental Example 1 The alkoxy-covalently modified MXene (MX-OEt) prepared in Example 1 was dispersed in ethanol and stored. Solvent exchange was performed by centrifugation, and MX-OEt was dispersed in various solvents of different polarities (10 mL of each solvent) at the same concentration (0.4 mg / mL). All dispersions remained homogeneous and stable, without any visible precipitation or stratification. As a comparison, the original Ti3C2T was... x The MXene aqueous dispersion was then attempted to be dispersed in the aforementioned organic solvents in the same manner. The dispersion of unmodified and modified MXene in the solvents is shown below. Figure 1 and Figure 2 As shown.
[0031] The results showed that unmodified MXene agglomerated and precipitated immediately or within a short time in various solvents, and the supernatant quickly became clear. In contrast, modified MXene could be stably dispersed in various solvents. This experiment directly demonstrated the excellent amphiphilic dispersion ability of modified MXene.
[0032] Experimental Example 2 The electrical properties of films prepared with and without modified MXene from Example 1 were monitored for 15 days at room temperature and 80% relative humidity. A Keithley 2450 source meter was used to monitor the resistance changes using the two-terminal method. The results are as follows: Figure 3 As shown.
[0033] The results show that the modification treatment significantly altered the aging behavior of the material: the conductivity of the unmodified MXene film remained at around 20% after 15 days. In contrast, the modified MXene film exhibited a more gradual initial decay rate (remaining at around 70% after 15 days), demonstrating the effective barrier effect of surface hydrophobication treatment against water and oxygen erosion in the short term.
[0034] Experimental Example 3 The modified MXene prepared according to Example 1 was dispersed in ethanol to prepare four different concentrations of MX-OEt / ethanol stock solutions (sodium ethoxide content of 10%, 20%, 50%, and 100%, and stock solution concentrations of 3.17 mg / mL, 3.67 mg / mL, 2.23 mg / mL, and 3.5 mg / mL, respectively). These solutions were stored in different reagent bottles for subsequent evaluation. All inks showed no gelation or sedimentation after being sealed and allowed to stand for one week, demonstrating excellent operational stability.
[0035] An electrohydraulic printing system was employed, equipped with a precision micro-injection pump and a high-voltage power supply, with a nozzle inner diameter of 80 μm. Printing was conducted using 100% modified MX-OEt / ethanol ink (3.5 mg / mL) and unmodified MXene / ethanol ink as printing materials, under parameters including 3 kV voltage, 30 kPa pressure, 5 mm / s printing speed, and single-layer printing. The printing results are shown below. Figure 4 and Figure 5 As shown.
[0036] The results showed that unmodified MXene could not complete printing, while modified MXene could print normally.
[0037] Furthermore, by adjusting parameters such as voltage, air pressure, printing speed, and needle distance, the jet velocity and linewidth can be controlled, resulting in the printing of MXene films with different linewidths, such as... Figure 6 As shown. Therefore, printing efficiency and accuracy can be controlled by adjusting the parameters.
[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing alkoxy-covalently modified MXene, characterized in that, Includes the following steps: (1) Centrifuge the aqueous dispersion of monolayer MXene, then wash it with an organic solvent, and then disperse it in the organic solvent to obtain an organic dispersion of MXene; (2) Dissolve sodium alkoxy in toluene, then add the MXene organic dispersion obtained in step (1), stir the reaction in an inert gas atmosphere, centrifuge after the reaction is completed, and then wash with hydrochloric acid and ethanol to obtain alkoxy covalently modified MXene.
2. The method for preparing alkoxy-covalently modified MXene as described in claim 1, characterized in that, In step (1), the organic solvent is dimethyl sulfoxide or N,N-dimethylformamide.
3. The method for preparing alkoxy-covalently modified MXene as described in claim 1, characterized in that, In step (1), the concentration of the MXene organic dispersion is 1-10 mg / mL.
4. The method for preparing alkoxy-covalently modified MXene as described in claim 1, characterized in that, In step (2), the sodium alkoxy is sodium ethoxide or sodium phenolate.
5. The method for preparing alkoxy-covalently modified MXene as described in claim 1, characterized in that, In step (2), the mass-to-volume ratio of sodium alkoxy and toluene is 2-20 mg: 1 mL.
6. The method for preparing alkoxy-covalently modified MXene as described in claim 1, characterized in that, In step (2), the amount of sodium alkoxy is 10-100% of the mass of MXene in the MXene organic dispersion.
7. The method for preparing alkoxy-covalently modified MXene as described in claim 1, characterized in that, In step (2), the reaction is stirred at 30-50°C for 3-24 h.
8. Alkoxy-covalently modified MXene prepared by the method of any one of claims 1-7.
9. The application of the alkoxy-covalently modified MXene according to claim 8 in the preparation of electrofluid printing ink.
10. A highly conductive ink suitable for electrohydraulic printing, characterized in that, It is prepared from the alkoxy-covalently modified MXene as described in claim 8.