A method of patterned additive manufacturing of a metal organic framework material

Abstract

The application provides a metal organic framework material patterning additive manufacturing method, and relates to the technical field of additive manufacturing.The application proposes a new strategy of MOF micro-nano additive manufacturing based on mechanical chemical fixation and hydrothermal conversion, and the application utilizes the mechanical friction effect of a friction pair on the surface of a base material to fix metal oxide precursor micro-nano structures in a preset track in a directional and quantitative manner, so as to form an accurate patterned prototype; then, the fixed precursor is reacted with an organic ligand through a hydrothermal reaction, so as to be directionally converted into a corresponding MOF structure.The application implements the patterning construction of the precursor and the conversion of the MOF in steps, so as to not only ensure the fineness of the precursor structure, but also ensure the sufficiency and crystallinity of the MOF conversion.The whole process does not need a mask, does not need electron beam exposure, and does not need a developing solution treatment, has low requirements on equipment, is simple to operate, has a cost significantly lower than that of a traditional photolithography technology, and has good material universality and base adaptability.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and more particularly to a method for patterned additive manufacturing of metal-organic framework materials. Background Technology

[0002] Metal-organic frameworks (MOFs) with micro- and nano-structures have shown great potential in applications such as microsensing, optoelectronic devices, and catalysis. However, achieving directional, localized, and patterned integration of MOF materials at the micro- and nano-scale remains a bottleneck restricting their practical application in devices. Traditional micro- and nano-fabrication techniques, such as photolithography and electron beam etching, can achieve high-precision patterning, but they generally suffer from problems such as complex processes, expensive equipment, high energy consumption, and environmental pollution caused by the use of developing solutions, and are difficult to apply to porous and fragile functional materials such as MOFs. In recent years, although some studies have attempted to combine MOFs with microfabrication techniques, such as the development of direct X-ray and electron beam lithography based on halogenated ZIF materials to achieve high-resolution patterning at sub-50 nm, this method still relies on large synchrotron radiation sources or electron beam lithography equipment, which is costly and requires the use of specific halogenated ligands, limiting its versatility and large-scale application. Other researchers have developed an electron beam-induced, solvent-free, bottom-up ZIF patterning method. This method suppresses MOF growth in specific regions by pre-treating electron beam-sensitized metal oxide precursors, achieving patterns with feature sizes of approximately 100 nm. This technique avoids the liquid development step, which is a significant advancement. However, its core still relies on expensive electron beam lithography systems for writing, making it difficult to meet the demands for low-cost and convenient manufacturing. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a patterned additive manufacturing method for metal-organic framework materials. The manufacturing method provided by this invention is simple to operate, low in cost, and requires no complex masks, no solvent development, and no expensive exposure equipment.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for patterned additive manufacturing of metal-organic framework materials, comprising the following steps: The friction pair is subjected to frictional motion on the surface of a substrate coated with a metal oxide dispersion according to a set motion trajectory. At the position of the motion trajectory, a metal oxide-based micro / nano structure with a height of nanometer is formed, resulting in a substrate bearing the patterned metal oxide-based micro / nano structure. During the frictional motion, the load is 0.01~1.0N, the sliding speed is 10~3000μm / s, and the ambient temperature is 20~30℃. The substrate carrying the patterned metal oxide-based micro / nano structure is placed in an organic ligand solution for hydrothermal reaction to form a patterned metal-organic framework micro / nano structure on the substrate.

[0005] Preferably, the metal oxide in the metal oxide dispersion includes one or more of ZnO, Co3O4 and CuO, and the particle size of the metal oxide is 15~500nm.

[0006] Preferably, the dispersion medium of the metal oxide dispersion is ethanol or polyalphaolefin, and the mass fraction of the metal oxide in the metal oxide dispersion is 0.1-30%.

[0007] Preferably, the friction pair is made of steel, copper, nickel, or ceramic material; the friction pair is a spherical friction pair with a diameter of 0.1~3mm.

[0008] Preferably, the substrate is made of metal, alloy, silicon nitride, silicon, ceramic, polymer or ITO glass.

[0009] Preferably, the relative humidity of the environment is 20-70% during the frictional motion.

[0010] Preferably, the frictional motion is a reciprocating frictional motion with a reciprocating distance of 40~2000μm and a friction cycle of 50~10000 times.

[0011] Preferably, the organic ligand in the organic ligand solution includes one or more of 2-methylimidazole, terephthalic acid, and 3,4-dichloroimidazole, and the concentration of the organic ligand in the organic ligand solution is 0.05~10 g / L.

[0012] Preferably, the hydrothermal reaction is carried out at a temperature of 60~120℃ for a time of 15min~24h.

[0013] Preferably, the height of the metal oxide-based micro / nano structure is 10-200 nm and the width is 5-35 μm; the height of the patterned metal-organic framework micro / nano structure is 100-350 nm.

[0014] This invention provides a patterned additive manufacturing method for metal-organic framework (MOF) materials. It proposes a novel MOF micro / nano additive manufacturing strategy based on a combination of mechanochemical fixation and hydrothermal conversion. This invention utilizes the mechanical friction of a friction pair on a substrate surface to directionally and quantitatively fix metal oxide precursor micro / nano structures along a predetermined trajectory, forming a precise patterned prototype. Then, by controlling the hydrothermal reaction, the fixed precursor reacts with organic ligands, directionally converting into the corresponding MOF structure. This invention implements the precursor patterning and MOF conversion processes step-by-step, ensuring not only the precision of the precursor structure but also the sufficiency and crystallinity of the MOF conversion. The entire process requires no masks, no electron beam exposure, and no developer treatment, has low equipment requirements, is simple to operate, and is significantly less expensive than traditional photolithography. It also possesses good material versatility and substrate adaptability, enabling the acquisition of patterned MOF micro / nano structures with feature sizes down to the hundreds of nanometers level. This provides a novel technical approach for the efficient and green integration of MOF materials in micro / nano devices. Attached Figure Description

[0015] Figure 1 The image shows the local three-dimensional microstructure (a) and two-dimensional contour curve (b) of the ZIF-8 sample prepared on the substrate surface in Example 1. Figure 2 This is a light microscope image of the ZIF-8 patterned sample prepared on the substrate surface in Example 2; Figure 3 The image shows the local three-dimensional microstructure (a) and two-dimensional contour curve (b) of the ZIF-67 sample prepared on the substrate surface in Example 4. Figure 4 The image shows the local three-dimensional microstructure (a) and two-dimensional contour curve (b) of the MOF-5 sample prepared on the substrate surface in Example 5. Detailed Implementation

[0016] This invention provides a method for patterned additive manufacturing of metal-organic framework materials, comprising the following steps: The friction pair is subjected to frictional motion on the surface of a substrate coated with a metal oxide dispersion according to a set motion trajectory. At the position of the motion trajectory, a metal oxide-based micro / nano structure with a height of nanometer is formed, resulting in a substrate bearing the patterned metal oxide-based micro / nano structure. During the frictional motion, the load is 0.01~1.0N, the sliding speed is 10~3000μm / s, and the ambient temperature is 20~30℃. The substrate carrying the patterned metal oxide-based micro / nano structure is placed in an organic ligand solution for hydrothermal reaction to form a patterned metal-organic framework micro / nano structure on the substrate.

[0017] In this invention, all raw materials / equipment involved are commercially available products well known in the art.

[0018] In this invention, a friction pair is subjected to frictional motion on the surface of a substrate coated with a metal oxide dispersion according to a set motion trajectory. At the position of the motion trajectory, a metal oxide-based micro / nano structure with a height of nanometer is formed by directional growth, resulting in a substrate carrying a patterned metal oxide-based micro / nano structure.

[0019] In this invention, the friction pair is preferably made of steel (such as GCr15 steel), copper, nickel, or ceramic. This invention does not have specific requirements for the ceramic material; any ceramic material well-known to those skilled in the art, such as zirconium oxide or silicon carbide, can be used. The friction pair made of the aforementioned material possesses chemical stability. In this invention, the friction pair is preferably a spherical friction pair, and the diameter of the spherical friction pair is preferably 0.1~3 mm, which can be 0.3, 0.5, 1, 2, or 3 mm. In this invention, the substrate material is preferably metal, alloy (such as steel), silicon nitride, silicon (such as single-crystal silicon), ceramic, polymer, or ITO glass. In this invention, the hardness matching degree between the friction pair and the substrate affects the wear pattern and stress magnitude of the friction interface: when the hardness of the friction pair is much higher than that of the substrate (e.g., zirconium dioxide pair / steel substrate), the surface of the substrate is easily plowed, causing wear on the substrate; when the hardness of the friction pair is comparable to that of the substrate (e.g., steel pair / steel substrate, zirconium dioxide pair / silicon nitride substrate), the nanoparticles in the metal oxide dispersion generate micro-nano structures in a predetermined trajectory through shear force and the mechanical friction of the friction pair on the substrate surface; when the hardness of the friction pair is lower than that of the substrate (e.g., copper pair / steel substrate), the friction pair itself wears more severely, and its wear debris may recombine with the substrate, forming wear debris on the movement trajectory of the substrate.

[0020] In this invention, the substrate is preferably pretreated before use. The preferred method for pretreatment is to ultrasonically clean the substrate in acetone, ethanol and deionized water for 15 minutes each, and then dry it with high-purity nitrogen.

[0021] In this invention, the metal oxide in the metal oxide dispersion preferably includes one or more of ZnO (zinc oxide), Co3O4 (cobalt tetroxide), and CuO (copper oxide). The particle size of the metal oxide is preferably 15-500 nm, the particle size of ZnO is more preferably 15-50 nm, and the particle sizes of Co3O4 and CuO are more preferably 20-250 nm. In this invention, the dispersion medium of the metal oxide dispersion is preferably ethanol or polyalphaolefin, and the polyalphaolefin can be PAO4; when the metal oxide is ZnO, the dispersion medium is preferably ethanol, and when the metal oxide is Co3O4 or CuO, the dispersion medium is preferably polyalphaolefin. In this invention, the mass fraction of the metal oxide in the metal oxide dispersion is preferably 0.1-30%, and can be 5-20%, specifically 10%, 15%, or 18%. The quantitative fixation of the metal oxide precursor on the substrate can be achieved by controlling the concentration of the metal oxide in the metal oxide dispersion. In this invention, the preferred method for preparing the metal oxide dispersion is to mix the metal oxide with a dispersion medium and then ultrasonically disperse it for 30 minutes to ensure uniform dispersion of the metal oxide.

[0022] In this invention, during the frictional motion, the load is 0.01~1.0N, which can be 0.05, 0.1, 0.15, 0.2, 0.3, 0.4 or 0.5N; the sliding speed is 10~3000μm / s, which can be 500, 800, 1000, 1200 or 2000μm / s; and the ambient temperature is 20~30℃, which can be 22, 25 or 30℃. In this invention, the load determines the deposition effect and structural stability. If the load is too low (<0.01N), the contact stress is insufficient, the mechanochemical interaction is weak, the metal oxide particles cannot be stably adsorbed on the substrate surface, and the precursor pattern is discontinuous and easy to fall off. If the load is moderate (0.01~1.0N), the stress is just enough to allow the particles to be deposited in a directional manner through physical and chemical interactions, forming a uniform micro-nano structure with a height of 10~200nm and clear boundaries, while avoiding substrate wear. If the load is too high (>1.0N), the substrate surface will be worn, the particles will be easily wrapped and detached by the wear debris, the pattern will be destroyed, and impurities will be introduced, affecting the subsequent MOF conversion. In this invention, the sliding speed controls the deposition uniformity and pattern accuracy. If the sliding speed is too slow (<10μm / s), the contact time between the friction pair and the substrate is too long, resulting in excessive deposition of local particles, leading to uneven structural thickness, severe agglomeration, and a pattern width exceeding the preset range. If the sliding speed is moderate (10~3000μm / s), the contact time matches the particle adsorption rate, resulting in a highly uniform deposition structure that can accurately replicate the friction trajectory (length 40~2000μm) while promoting the renewal of the lubricant (i.e., metal oxide dispersion) and avoiding abnormal local concentrations. If the sliding speed is too fast (>3000μm / s), the contact time is too short, the mechanochemical action is insufficient, the particles are not firmly adsorbed, and the pattern is sparse and has poor continuity. In this invention, the ambient temperature ensures process stability and particle dispersibility. If the ambient temperature is too low (<20℃), the lubricant viscosity increases, the metal oxide particle dispersibility deteriorates, leading to agglomeration, slow interfacial molecular movement, and decreased deposition efficiency. At a moderate temperature (20~30℃), the lubricant has optimal fluidity, particles are uniformly dispersed, mechanochemical interactions are mild and controllable, the precursor structure is stable, and no additional temperature control equipment is needed, reducing costs. If the temperature is too high (>30℃), the lubricant evaporates rapidly, local particle concentration increases sharply, structural thickness becomes uneven, and some metal oxides may undergo phase transitions, reducing the reactivity with subsequent organic ligands. This invention combines load, sliding speed, and ambient temperature to obtain a metal oxide precursor pattern with regular morphology and strong adhesion, laying the foundation for the complete conversion of MOFs.

[0023] In this invention, during the frictional motion, the relative humidity of the environment is preferably 20-70%, which can be 30%, 35%, 40%, 45% or 50%. The frictional motion is preferably reciprocating frictional motion, the reciprocating distance is preferably 40-2000μm, which can be 50, 100, 400, 500, 600 or 1000μm. The friction cycle is preferably 50-10000 times, which can be 300, 400, 500, 1000, 2000 or 5000 times.

[0024] In this invention, the height of the metal oxide-based micro / nano structure is preferably 10-200 nm, and the width is preferably 5-35 μm.

[0025] In this invention, the preferred preparation operation of the substrate bearing the patterned metal oxide-based micro / nano structure is as follows: the pretreated substrate is fixed on a precision displacement platform, 100-200 μL of the prepared metal oxide dispersion is dropped onto the substrate surface using a micropipette, a spherical friction pair with a diameter of 0.1-3 mm is selected, friction parameters (including load, sliding speed, reciprocating distance, and friction cycle) and environmental conditions (including ambient temperature and relative humidity) are set, and the required motion trajectory is designed through a computer control system, so that the friction pair moves along the set motion trajectory on the substrate surface.

[0026] This invention uses a metal oxide dispersion (suspension) as a precursor. By setting up a friction pair to generate frictional contact with the substrate sample in a specific medium environment, the metal oxide precursor undergoes periodic frictional motion along a set trajectory under a preset load and sliding speed. The negative wear effect is achieved by utilizing tribochemical action, which promotes mechanochemical action in the contact area. Through mechanochemical-induced directional deposition, the metal oxide precursor is directionally (i.e., the formation of micro / nano structures is precisely controlled at the position of the motion trajectory) and quantitatively (referring to the growth height and size of the micro / nano structures) fixed on the preset trajectory of the substrate surface, thus completing the patterned construction of the precursor for MOF preparation. The resulting micro / nano structures can achieve a precision of 10~200nm. At the same time, by designing the motion trajectory, specific patterned micro / nano structures, such as straight lines, curves, or complex patterns, can be prepared on the substrate surface as needed.

[0027] After obtaining a substrate carrying a patterned metal oxide-based micro / nano structure, the present invention places the substrate carrying the patterned metal oxide-based micro / nano structure in an organic ligand solution for hydrothermal reaction to form a patterned metal-organic framework micro / nano structure on the substrate.

[0028] In this invention, the organic ligand in the organic ligand solution preferably includes one or more of 2-methylimidazole, terephthalic acid, and 3,4-dichloroimidazole. The organic ligand solution is an aqueous solution or an organic solution (such as an ethanol solution) of the organic ligand. The concentration of the organic ligand in the organic ligand solution is preferably 0.05~10 g / L, and can be 2, 2.5, 3, or 4 g / L. This invention does not have particular requirements on the amount of organic ligand solution added, as long as it is sufficient to completely immerse the substrate carrying the patterned metal oxide-based micro / nano structure.

[0029] In this invention, when preparing the metal-organic framework material ZIF-8, the metal oxide in the metal oxide dispersion is ZnO, and the organic ligand solution is an aqueous solution of 2-methylimidazole; when preparing the metal-organic framework material ZIF-67, the metal oxide in the metal oxide dispersion is Co3O4, and the organic ligand solution is an aqueous solution of 2-methylimidazole; when preparing the metal-organic framework material ZIF-71, the metal oxide in the metal oxide dispersion is ZnO, and the organic ligand solution is an aqueous solution of 3,4-dichloroimidazole; when preparing the metal-organic framework material MOF-5, the metal oxide in the metal oxide dispersion is ZnO, and the organic ligand solution is an ethanol solution of terephthalic acid.

[0030] In this invention, the substrate bearing the patterned metal oxide-based micro / nano structure is preferably placed in a high-pressure reactor lined with polytetrafluoroethylene, and an organic ligand solution is added thereto to carry out a hydrothermal reaction.

[0031] In this invention, the hydrothermal reaction temperature is preferably 60~120℃, but can be 80, 90, or 100℃, and the time is preferably 15min~24h, but can be 1, 2, 4, 6, or 8h. During the hydrothermal reaction, the metal oxide precursor in the substrate carrying the patterned metal oxide-based micro / nanostructure undergoes a solid-liquid interface reaction with the organic ligand, directionally transforming into a metal-organic framework (MOF) micro / nanostructure, and the transformed MOF micro / nanostructure completely inherits the patterned morphology characteristics of the precursor. In this invention, the morphology and transformation degree of the MOF micro / nanostructure can be precisely controlled by adjusting the concentration of the organic ligand solution, the hydrothermal reaction temperature, and the time.

[0032] After the hydrothermal reaction is completed, the substrate with the patterned metal-organic framework micro / nanostructure is preferably removed after natural cooling to room temperature and then cleaned and dried sequentially. In this invention, the cleaning is preferably performed by alternating between deionized water and ethanol three times to remove residual ligands and byproducts physically adsorbed on the substrate surface; the drying is preferably carried out in an inert gas atmosphere or vacuum environment (such as a vacuum drying oven), the drying temperature is preferably 40~80℃, and the drying time is preferably 1~12h, after which the final patterned MOF micro / nanostructure product is obtained.

[0033] In this invention, the height of the patterned metal-organic framework micro / nano structure is preferably 100-350 nm, and can be 125, 150, 180, 200, 220 or 270 nm, and the width is preferably 5-35 μm.

[0034] This invention provides a MOF micro / nano additive manufacturing method based on a combination of mechanochemical and hydrothermal conversion. By combining simple and low-cost mechanochemical-induced micro / nano structure growth with hydrothermal reactions, it achieves the directional, localized, and patterned fabrication of metal-organic framework materials on various micro / nano-scale substrates. The resulting micro / nano structures exhibit clear pattern boundaries and uniform morphology, with heights at the hundreds of nanometers level. This invention eliminates the need for complex masks, expensive photolithography or electron beam exposure equipment, and solvent development. It separates the controllable fabrication of metal oxide precursor micro / nano structures with subsequent hydrothermal conversion, ensuring both the precision of the precursor micro / nano structures and the sufficiency of MOF conversion, significantly reducing process complexity and manufacturing costs. Compared with traditional MOF micro / nano fabrication methods such as photolithography and electron beam etching, the method of this invention has advantages such as low cost, simple process, environmentally friendly process, applicability to large-area substrates, customization, and strong scalability. It is applicable to a variety of substrates and suitable for the integration of patterned functional MOF materials in fields such as microsensing, photoluminescence, optoelectronic devices, and catalysis, providing a highly universal, green, and efficient micro / nano functional structure integration solution for these fields. Furthermore, by adjusting the type of precursor metal oxide and organic ligand, this invention can achieve the micro / nano fabrication of different types of MOF materials, exhibiting good material versatility.

[0035] To further illustrate the present invention, the patterned additive manufacturing method for metal-organic framework materials provided by the present invention will be described in detail below with reference to examples, but these should not be construed as limiting the scope of protection of the present invention.

[0036] Example 1 Fabrication of ZIF-8 micro / nano structures: Zirconia spheres with a diameter of 1 mm were used as the friction pair, and a single-crystal silicon wafer was used as the substrate (ultrasonically cleaned for 15 min each in acetone, ethanol, and deionized water, then dried with high-purity nitrogen). The lubricating dispersion between the friction pair and the substrate surface (coated onto the substrate surface) was a 15 wt% ZnO (particle size 15~25 nm) ethanol solution. The friction parameters were set as follows: load 0.1 N, sliding speed 1000 μm / s, reciprocating distance 500 μm, and friction cycle 300 times; ambient temperature 25℃, relative humidity 40%. Under these conditions, the friction pair was subjected to frictional motion on the substrate surface according to the set trajectory. After friction printing, the sample was hydrothermally reacted with a 2 g / L 2-methylimidazole aqueous solution at 80℃ for 6 h. The obtained ZIF-8 micro / nano structure had an average height of 270 nm and a width of approximately 8 μm, exhibiting good patterned structure and crystallinity.

[0037] Figure 1 The local three-dimensional microstructure (a) and two-dimensional profile curve (b) of the ZIF-8 sample prepared on the substrate surface in Example 1 are shown. Figure 1 In (b), Profile1, Profile2, Profile3, and Profile4 represent four different locations selected from the surface for two-dimensional profile analysis.

[0038] Example 2 Fabrication of ZIF-8 patterned micro / nano structures: Zirconia spheres with a diameter of 0.3 mm were used as the friction pair, and a single-crystal silicon wafer was used as the substrate (ultrasonically cleaned for 15 min each in acetone, ethanol, and deionized water, then dried with high-purity nitrogen). The lubricating dispersion between the friction pair and the substrate surface was a 15 wt% ZnO (particle size 15~25 nm) ethanol solution. The friction parameters were set as follows: load 0.4 N, sliding speed 500 μm / s, reciprocating distance 500 μm, and friction cycle 1000 times; ambient temperature 25℃, relative humidity 40%. Under these conditions, the friction pair was subjected to frictional motion on the substrate surface according to the set trajectory. After friction printing, the sample was hydrothermally reacted with a 2 g / L 2-methylimidazole aqueous solution at 80℃ for 6 h. The obtained ZIF-8 micro / nano structure had an average height of 220 nm and a width of approximately 5 μm, exhibiting good patterned structure and crystallinity.

[0039] Figure 2 This is a light microscope image of the ZIF-8 patterned sample prepared on the substrate surface in Example 2.

[0040] Example 3 Fabrication of ZIF-8 micro / nano structures: Zirconia spheres with a diameter of 0.5 mm were used as the friction pair, and a single-crystal silicon wafer was used as the substrate (ultrasonically cleaned for 15 min each in acetone, ethanol, and deionized water, then dried with high-purity nitrogen). The lubricating dispersion between the friction pair and the substrate surface was a 15 wt% ZnO (particle size 15~25 nm) ethanol solution. The friction parameters were set as follows: load 0.05 N, sliding speed 2000 μm / s, reciprocating distance 100 μm, and friction cycle 500 times; ambient temperature 25℃, relative humidity 40%. Under these conditions, the friction pair was subjected to frictional motion on the substrate surface according to the set trajectory. After friction printing, the sample was hydrothermally reacted with a 4 g / L 2-methylimidazole aqueous solution at 90℃ for 4 h. The obtained ZIF-8 micro / nano structure had an average height of 180 nm and a width of approximately 6 μm, exhibiting good pattern fidelity and crystallinity.

[0041] Example 4 Fabrication of ZIF-67 micro / nano structures: Zirconia steel balls with a diameter of 1 mm were used as the friction pair, and silicon nitride wafers were used as the substrate (ultrasonically cleaned for 15 min each in acetone, ethanol, and deionized water, then dried with high-purity nitrogen). The lubricating dispersion between the friction pair and the substrate surface was a 10 wt% Co3O4 PAO4 base oil dispersion (particle size 200~250 nm). The friction parameters were set as follows: load 0.5 N, sliding speed 800 μm / s, reciprocating distance 400 μm, and friction cycle 5000 times; ambient temperature 22℃, relative humidity 35%. Under these conditions, the friction pair was subjected to frictional motion on the substrate surface according to the set trajectory. After friction printing, the sample was hydrothermally reacted with a 0.03 mol / L 2-methylimidazole aqueous solution at 80℃ for 6 h. The obtained ZIF-67 micro / nano structure had a height of approximately 220 nm and a width of approximately 23 μm, with good structural uniformity.

[0042] Figure 3 The local three-dimensional microstructure (a) and two-dimensional profile curve (b) of the ZIF-67 sample prepared on the substrate surface in Example 4 are shown. Figure 3 In (b), Profile1, Profile2, Profile3, and Profile4 represent four different locations selected from the surface for two-dimensional profile analysis.

[0043] Example 5 Fabrication of MOF-5 micro / nano structures: Silicon carbide spheres with a diameter of 0.5 mm were used as the friction pair, and ITO glass was used as the substrate (ultrasonically cleaned for 15 min each in acetone, ethanol, and deionized water, then dried with high-purity nitrogen). The lubricating dispersion between the friction pair and the substrate surface was an 18 wt% ZnO (particle size 15~25 nm) ethanol solution. The friction parameters were set as follows: load 0.15 N, sliding speed 1200 μm / s, reciprocating distance 600 μm, and friction cycle 400 times; ambient temperature 30℃, relative humidity 45%. Under these conditions, the friction pair was subjected to frictional motion on the substrate surface according to the set trajectory. After friction printing, the sample was hydrothermally reacted with a 2 g / L terephthalic acid ethanol solution at 120℃ for 2 h. The obtained MOF-5 micro / nano structure had a height of 125 nm and a width of approximately 4.6 μm.

[0044] Figure 4 The local three-dimensional microstructure (a) and two-dimensional profile curve (b) of the MOF-5 sample prepared on the substrate surface in Example 5 are shown. Figure 4 In (b), Profile1, Profile2, and Profile3 represent two-dimensional profile analysis performed at three different locations selected from the surface.

[0045] This invention achieves high-precision patterning of various MOF materials by optimizing friction parameters and hydrothermal reaction conditions. The prepared MOF micro / nano structures exhibit good morphology control and crystallinity, providing an effective technical means for the integrated application of MOF materials in micro / nano devices.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for patterned additive manufacturing of metal-organic framework materials, characterized in that, Includes the following steps: The friction pair is subjected to frictional motion on the surface of a substrate coated with a metal oxide dispersion according to a set motion trajectory. At the position of the motion trajectory, a metal oxide-based micro / nano structure with a height of nanometer is formed, resulting in a substrate bearing the patterned metal oxide-based micro / nano structure. During the frictional motion, the load is 0.01~1.0N, the sliding speed is 10~3000μm / s, and the ambient temperature is 20~30℃. The substrate carrying the patterned metal oxide-based micro / nano structure is placed in an organic ligand solution for hydrothermal reaction to form a patterned metal-organic framework micro / nano structure on the substrate.

2. The method for patterned additive manufacturing of metal-organic framework materials according to claim 1, characterized in that, The metal oxide in the metal oxide dispersion includes one or more of ZnO, Co3O4 and CuO, and the particle size of the metal oxide is 15~500nm.

3. The method for patterned additive manufacturing of metal-organic framework materials according to claim 1 or 2, characterized in that, The dispersion medium of the metal oxide dispersion is ethanol or polyalphaolefin, and the mass fraction of the metal oxide in the metal oxide dispersion is 0.1-30%.

4. The method for patterned additive manufacturing of metal-organic framework materials according to claim 1, characterized in that, The friction pair is made of steel, copper, nickel, or ceramic material; the friction pair is a spherical friction pair with a diameter of 0.1~3mm.

5. The method for patterned additive manufacturing of metal-organic framework materials according to claim 1, characterized in that, The substrate is made of metal, alloy, silicon nitride, silicon, ceramic, polymer or ITO glass.

6. The method for patterned additive manufacturing of metal-organic framework materials according to claim 1, characterized in that, During the frictional motion, the relative humidity of the environment is 20-70%.

7. The method for patterned additive manufacturing of metal-organic framework materials according to claim 1 or 6, characterized in that, The frictional motion is a reciprocating frictional motion with a reciprocating distance of 40~2000μm and a friction cycle of 50~10000 times.

8. The method for patterned additive manufacturing of metal-organic framework materials according to claim 1, characterized in that, The organic ligand in the organic ligand solution includes one or more of 2-methylimidazole, terephthalic acid, and 3,4-dichloroimidazole, and the concentration of the organic ligand in the organic ligand solution is 0.05~10 g / L.

9. The method for patterned additive manufacturing of metal-organic framework materials according to claim 1 or 8, characterized in that, The hydrothermal reaction is carried out at a temperature of 60~120℃ for a time of 15min~24h.

10. The method for patterned additive manufacturing of metal-organic framework materials according to claim 1, characterized in that, The metal oxide-based micro / nanostructure has a height of 10-200 nm and a width of 5-35 μm; the patterned metal-organic framework micro / nanostructure has a height of 100-350 nm.

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