A method and system for direct patterning of metal-organic framework materials based on friction printing

Abstract

This invention provides a method and system for the direct patterning of metal-organic framework (MOF) materials based on triboelectric printing, relating to the fields of micro / nano and additive manufacturing technology. The method utilizes a dispersion of MOFs as the printing medium. Through localized mechanochemical interactions between the friction pair and the substrate, solution enrichment effects, and interfacial crystallization processes, the MOF material is directly deposited and crystallized in situ on the substrate along a predetermined trajectory, forming highly controllable patterned MOF micro / nano structures. This invention eliminates the need for metal oxide precursors, hydrothermal conversion steps, masks, electron beam exposure, or developing solutions. By controlling the triboelectric load, sliding speed, solution composition, and printing path, direct patterned additive manufacturing of various MOFs can be achieved. The resulting MOF patterned structures exhibit clear boundaries, good crystallinity, and high controllability.

Description

Technical Field

[0001] This invention relates to the field of micro-nano and additive manufacturing technology, and in particular to a method and system for the direct patterning of metal-organic framework materials based on triboelectric printing. Background Technology

[0002] Metal-organic frameworks (MOFs) have broad application prospects in gas sensing, catalysis, electrochemistry, and optoelectronic devices due to their high specific surface area, tunable pore structure, and excellent functionality. However, how to integrate MOF materials onto substrate surfaces in a micro / nanoscale, patterned, and controllable manner has always been a bottleneck limiting their device applications. MOF micro / nanostructure fabrication methods mainly include photolithography, template-assisted deposition, and metal oxide precursor conversion. While photolithography and electron beam writing offer high resolution, they are expensive, complex, and potentially damage porous MOF structures. Precursor conversion methods rely on multi-step chemical reaction processes, making precise control of pattern contours difficult, and MOFs are generated under hydrothermal conditions, which are highly dependent on the substrate. Currently, there is no mature technology that can achieve one-step direct fabrication of patterned MOF micro / nanostructures. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a method and system for the direct patterning of metal-organic framework (MOF) materials based on triboelectric printing. This method enables the complete physical and one-step construction of patterned micro / nano structures of MOFs, significantly reducing process complexity and avoiding potential damage to the substrate and the MOF structure.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for direct patterning of metal-organic framework materials based on triboprinting, comprising the following steps: The friction pair moves along a set trajectory on the surface of a substrate coated with lubricating printing fluid to form a patterned metal-organic framework micro / nano structure on the substrate surface; the lubricating printing fluid is a dispersion of metal-organic framework material, and the dispersion medium of the dispersion fluid is ethanol or base oil; during the friction movement, the contact load is 0.01~2.0N, and the sliding speed is 100~5000μm / s.

[0005] Preferably, the metal-organic framework material includes one or more of ZIF-67, ZIF-8, and HKUST-1.

[0006] Preferably, the base oil includes one or more of PAO4, PAO10 and 500SN.

[0007] Preferably, the mass fraction of the metal-organic framework material in the dispersion is 1-20%.

[0008] Preferably, the frictional motion is a reciprocating frictional motion with a reciprocating distance of 100~2000μm and a reciprocating cycle of 50~5000 times.

[0009] Preferably, during the frictional motion, the ambient temperature is 25~150℃ and the relative humidity is 30~40%.

[0010] Preferably, the friction pair is spherical with a diameter of 0.1~3mm, and the material of the friction pair is ceramic or steel.

[0011] Preferably, the substrate is made of metal, silicon, ceramic, glass, ITO, polymer, or a flexible electronic substrate.

[0012] Preferably, the height of the patterned metal-organic framework micro / nano structure is 50-200 nm and the width is 10-50 μm.

[0013] This invention provides a direct patterning preparation system for metal-organic framework materials based on triboelectric printing, comprising a friction pair, a substrate, and a lubricating printing liquid. The lubricating printing liquid is a dispersion of the metal-organic framework material, and the dispersion medium of the dispersion liquid is ethanol or base oil. The lubricating printing liquid is applied between the friction pair and the surface of the substrate.

[0014] This invention provides a method for the direct patterning of metal-organic framework (MOF) materials based on triboelectric printing, comprising the following steps: a triboelectric pair is subjected to triboelectric motion along a predetermined trajectory on the surface of a substrate coated with a lubricating printing solution, thereby forming a patterned MOF micro / nano structure on the substrate surface; the lubricating printing solution is a dispersion of the MOF material, and the dispersion medium is ethanol or base oil; during the triboelectric motion, the contact load is 0.01~2.0N, and the sliding speed is 100~5000μm / s. This invention proposes a novel MOF micro / nano additive manufacturing strategy based on the combination of triboelectric printing and localized deposition of MOF materials. Compared with existing technologies, this invention has the following beneficial effects: This invention uses a dispersion of existing metal-organic framework materials (MOFs) with ethanol or base oil as a printing medium. Through the mechanical shearing, local compaction and extrusion of lubricating medium generated by the friction pair and the substrate surface, the MOF material is oriented, localized, and densified along a preset trajectory, thereby directly constructing a MOF micro-nano pattern structure with clear boundaries. This invention fully physicalizes and streamlines the construction process of micro-nano structures of MOF materials in one step, significantly reducing technical complexity and avoiding potential damage to the substrate and MOF structure. Combined with appropriate friction printing process parameters, it significantly improves the resolution and consistency of the structure. The entire process requires no mask, no exposure, and no development treatment, has extremely low equipment requirements, is easy to operate, and has a significantly lower cost than photolithography and other micro-nano processing technologies. The method of this invention is highly versatile for MOF material types and substrate types, and can be applied to various MOF materials such as ZIF-8, ZIF-67, and HKUST-1, and is compatible with various substrates such as silicon, glass, ceramics and flexible polymers; This invention provides a novel process route for the green and efficient integration of MOF materials in fields such as microsensing, flexible electronics, optoelectronic devices, and catalytic microstructures. Attached Figure Description

[0015] Figure 1 The cross-sectional morphology (a) and elemental distribution (b) of the ZIF-67 micro / nano structure prepared on the substrate surface in Example 1 are shown. Figure 2 The above are the AFM characterization results of the ZIF-67 micro / nano structure samples prepared on the substrate surface in Example 2. Figure 2 (a) shows the local three-dimensional micro-morphology, (b) shows the two-dimensional contour curve, and (c) shows the AFM high-magnification scan image; Figure 3 Examples of ZIF-67 patterning prepared on the substrate surface in Example 3; Figure 4 The ZIF-67 patterned array prepared on the substrate surface in Example 3 is shown. Detailed Implementation

[0016] This invention provides a method for direct patterning of metal-organic framework materials based on triboprinting, comprising the following steps: The friction pair moves along a set trajectory on the surface of a substrate coated with a lubricating printing fluid (also known as lubricant) to form a patterned metal-organic framework micro / nano structure on the substrate surface; the lubricating printing fluid is a dispersion of metal-organic framework material, and the dispersion medium of the dispersion fluid is ethanol or base oil; during the friction movement, the contact load is 0.01~2.0N, and the sliding speed is 100~5000μm / s.

[0017] Unless otherwise specified, all raw materials and equipment involved in this invention are commercially available products well known in the art.

[0018] In this invention, the friction pair is preferably spherical, with a diameter preferably of 0.1~3mm, which can be 0.1~1mm, specifically 0.3, 0.5 or 1mm. The material of the friction pair is preferably ceramic or steel, such as zirconium oxide or silicon carbide, and such as GCr15 steel. The material of the substrate is preferably metal, silicon (such as single crystal silicon wafer), ceramic (such as silicon nitride wafer), glass, ITO, polymer (such as flexible polymer substrate) or flexible electronic substrate.

[0019] In this invention, the substrate is preferably pretreated before use. The pretreatment method preferably involves sequentially cleaning and drying the substrate. Cleaning preferably involves ultrasonically cleaning the substrate in acetone, anhydrous ethanol, and deionized water for 15 minutes each to remove surface oil, particles, and impurities (for flexible polymer substrates (such as PI, PET, etc.), the same solvent cleaning method or a low-mask-pressure surface treatment method can be used for cleaning). Drying is preferably done by blowing with high-purity nitrogen. The pretreated substrate is then placed in a clean environment for later use.

[0020] In this invention, the metal-organic framework (MOF) material preferably includes one or more of ZIF-67, ZIF-8, and HKUST-1. The appropriate MOF material is selected according to the type of MOF to be printed. The MOF material can be in the form of two-dimensional sheets or particles. When the MOF material is in the form of two-dimensional sheets, its length is preferably 5-10 μm and its thickness is preferably 100-300 nm. When the MOF material is in the form of particles, its particle size is preferably 200 nm-1 μm. In this invention, the dispersion medium of the dispersion liquid is ethanol or a base oil. The base oil preferably includes one or more of PAO4, PAO10, and 500SN. In this invention, the type of dispersion medium plays a crucial regulatory role in achieving the local enrichment, directional deposition, and in-situ crystallization process of the MOF precursor. As a microenvironment carrier for the reaction, the dispersion medium directly affects the solubility, diffusion rate, and interfacial behavior of the precursor through its physicochemical properties, thereby influencing the efficiency and accuracy of the entire process. During the local enrichment stage, the volatility of the dispersion medium and its ability to dissolve metal-organic framework precursors jointly determine whether critical supersaturation can be rapidly reached at a specific contact interface, triggering nucleation. During the directional deposition stage, the surface tension, viscosity, and interaction between the dispersion medium and the substrate dominate the wetting and spreading behavior of the precursor solution at the interface, guiding crystal growth along a specific orientation. During the in-situ crystallization stage, the dispersion medium, as a participant in the reaction, regulates the kinetics of nucleation and growth through its polarity and coordination ability, and may also act as a structure-directing agent, influencing the structure and morphology of the final crystal.

[0021] In this invention, the mass fraction of the metal-organic framework (MOF) material in the dispersion is preferably 1-20%, and can be 5%, 10%, or 15%. The preferred method for preparing the MOF dispersion is to add the MOF material to a dispersion medium and then ultrasonically disperse (e.g., for 30 minutes) or perform high-speed shear mixing to ensure uniform and stable dispersion of the MOF material in the dispersion medium. The dispersion system used in this invention is a purely physical dispersion process and does not involve any chemical reactions.

[0022] In this invention, during the frictional motion, the contact load is 0.01~2.0N, which can be 0.05, 0.08, 0.1, 0.3, 0.5, 0.9, 1.0, or 2.0N, and the sliding speed is 100~5000μm / s, which can be 400, 800, 1000, 2000, 3000, or 5000μm / s. In this invention, the normal pressure generated by the contact load mainly drives the extrusion of the lubricating medium, promoting the local enrichment and compaction of MOF precursors in the contact area. The sliding speed, by controlling the shear rate, dominates the directional arrangement and efficient transport of particles, and synergistically regulates the residence time and frictional heat effect of the precursors in the reaction zone, thereby affecting the kinetics of in-situ crystallization. The matching of these two factors jointly determines the force-thermal-chemical microenvironment of the contact area: excessively high loads may lead to over-compaction or dry friction, while excessively high speeds may limit the sufficiency of the reaction. Therefore, optimizing the combination of load and velocity is the key to achieving the process from enrichment and directional deposition to complete crystallization, ultimately obtaining patterned MOF micro / nano structures with clear boundaries, dense structures, and good crystallization.

[0023] In this invention, the frictional motion is preferably reciprocating frictional motion, the reciprocating distance is preferably 100~2000μm, which can be 200, 500 or 1000μm, and the reciprocating cycle is preferably 50~5000 times, which can be 300, 500, 1000 or 2000 times; the ambient temperature during the frictional motion is preferably 25~150℃, when the dispersion medium of the dispersion is ethanol, the ambient temperature is further preferably 25~35℃, and when the dispersion medium of the dispersion is base oil, the ambient temperature is further preferably 80~150℃, which can be 80, 85, 90 or 95℃; the relative humidity during the frictional motion is preferably 30~40%, which can be 30~35%.

[0024] During the frictional motion, the normal pressure and shear force generated by the friction pair guide MOF nanoparticles to undergo local enrichment, directional deposition and in-situ crystallization in the contact area between the friction pair and the substrate surface (i.e., the friction area) (forming a dense stacked structure under local extrusion), resulting in patterned MOF micro / nano structures.

[0025] In this invention, the preferred steps for the direct patterning preparation of the metal-organic framework material are as follows: the pretreated substrate is fixed on a precision displacement platform, 20-200 μL of lubricating printing liquid is added to the surface of the substrate using a micropipette, so that a thin lubricating film is formed in the friction area, a spherical friction pair of a certain diameter is selected, and the friction printing parameters (including load, sliding speed, reciprocating distance, friction cycle, ambient temperature and ambient humidity) are set, and the friction pair is moved along a set trajectory (such as a straight line, curve or complex pattern) on the surface of the substrate. The normal pressure, shearing action and local extrusion effect of the dispersion medium (such as PAO4) generated at the interface cause the MOF material in the dispersion to continuously concentrate towards the friction contact area, and then deposited, arranged and formed a patterned structure with micro-nano scale under continuous mechanical compaction.

[0026] In this invention, after the patterning preparation is completed, the obtained sample is preferably cleaned and dried in sequence; the cleaning reagent is preferably petroleum ether; the drying temperature is preferably 40~80℃, and the drying time is preferably 1~12h. The cleaning and drying further remove excess dispersion medium and improve the compactness of the pattern structure.

[0027] In this invention, the height of the patterned metal-organic framework micro / nanostructure is preferably 50-200 nm, and can be 80, 100, 120, 150, or 200 nm; the width is preferably 10-50 μm, and can be 20, 25, 30, or 40 μm. The patterned metal-organic framework micro / nanostructure prepared by this invention has clear pattern boundaries and a highly uniform and dense crystalline structure, and its crystal structure retains the original characteristics of MOF (including morphology and pore features).

[0028] This invention, for the first time, utilizes a stable dispersion system, formed by mixing existing MOF materials with ethanol or base oil as the dispersion medium, as a lubricating printing solution. Through localized shearing, compaction, and lubricant removal effects between the friction pair and the substrate, the MOF material is locally deposited, densely packed, and patterned on the substrate surface along a predetermined path, directly obtaining MOF micro / nano patterned structures with clear boundaries. This invention uses existing MOF materials as printing materials and directly constructs patterned MOF micro / nano structures on the substrate surface through mechanical friction. The entire process requires no photolithography, chemical reactions, hydrothermal processes, or precursor systems, achieving true direct printing construction of MOF materials. This method is green, safe, requires simple equipment, is low-cost, and offers high pattern precision. It is adaptable to various substrates, including flexible substrates, providing a novel technological path for the integrated manufacturing of MOF materials in fields such as microsensors, electrochemical devices, optoelectronic devices, light-emitting devices, and catalytic microsystems.

[0029] This invention provides a system for the direct patterning of metal-organic framework (MOF) materials based on triboprinting, comprising a friction pair, a substrate, and a lubricating printing fluid. The lubricating printing fluid is a dispersion of the MOF material, and the dispersion medium is ethanol or a base oil. The lubricating printing fluid is applied between the friction pair and the substrate surface. In this invention, the specific conditions of the friction pair, substrate, and lubricating printing fluid are the same as those described in the previous technical solutions. The fabrication system provided by this invention enables the localized deposition of MOF nanomaterials, achieving one-step construction of patterned MOF micro / nano structures.

[0030] To further illustrate the present invention, the following detailed description, in conjunction with examples, of the method and system for direct patterning of metal-organic framework materials based on triboelectric printing provided by the present invention, should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1 Zirconia spheres with a diameter of 0.3 mm were used as the friction pair, and silicon nitride wafers were used as the substrate. A mixture of 5 wt% ZIF-67 (a two-dimensional MOF material with a length of 5-10 μm and a thickness of 100-300 nm) and 95 wt% PAO4 was used as the lubricant. The substrate surface was ground, polished, cleaned, and dried, and then fixed in a groove directly below the friction pair. 20 μL of lubricant was placed between the friction pair and the substrate using a pipette (the lubricant was dripped onto the substrate surface). The friction trajectory was set as a straight line. During the friction process, a load of 0.08 N, a sliding speed of 3000 μm / s, a reciprocating distance of 1000 μm, a friction cycle of 500 times, an ambient temperature of 85℃, and a relative humidity of 30% were used. After preparation, the sample was removed, cleaned with petroleum ether, and dried. The surface morphology and elemental distribution of the ZIF-67 micro / nanostructure sample prepared on the substrate surface in Example 1 are shown below. Figure 1 As shown, the interface structure is clear and the elements are evenly distributed.

[0032] Example 2 Zirconia spheres with a diameter of 0.3 mm were used as the friction pair, and silicon nitride wafers were used as the substrate. A lubricant was prepared by mixing 10 wt% ZIF-67 (a two-dimensional MOF material with a length of 5-10 μm and a thickness of 100-300 nm) with 90 wt% PAO4. The substrate surface was ground, polished, cleaned, and dried, and then fixed in a groove directly below the friction pair. 20 μL of lubricant was placed between the friction pair and the substrate using a pipette. The friction trajectory was set as a straight line. During friction, the load was 0.10 N, the sliding speed was 2000 μm / s, the reciprocating distance was 500 μm, the friction cycle was 1000 times, the ambient temperature was 95℃, and the relative humidity was 30%. After preparation, the sample was removed, cleaned with petroleum ether, and dried.

[0033] The AFM morphology of the ZIF-67 micro / nano structure sample prepared on the substrate surface in Example 2 is shown in Figure 2. Figure 2 Image (a) shows the local three-dimensional microstructure, (b) shows the two-dimensional profile curves (where Profile1, Profile2, and Profile3 represent two-dimensional profile analysis performed at three different locations selected from the surface), and (c) shows the AFM high-magnification scan image (2×2μm). The micro / nano structure is generally flat, with an average height of approximately 150nm and a width of approximately 25μm. Figure 2 As can be seen in (c), the surface of this micro-nano structure has granular structure, which is consistent with the morphological characteristics of ZIF-67 crystal form.

[0034] Example 3 Zirconia spheres with a diameter of 0.5 mm were used as the friction pair, and silicon nitride wafers were used as the substrate. A lubricant was prepared by mixing 10 wt% ZIF-67 (a two-dimensional MOF material with a length of 5-10 μm and a thickness of 100-300 nm) with 90 wt% PAO4. The substrate surface was ground, polished, cleaned, and dried, and then fixed in a groove directly below the friction pair. 20 μL of lubricant was placed between the friction pair and the substrate material using a pipette. Friction trajectories were set as triangular, circular, and rhomboid shapes. During friction, the load was 0.10 N, the sliding speed was 5000 μm / s, the reciprocating distance was 1000 μm, the friction cycle was 2000 times, the ambient temperature was 85℃, and the relative humidity was 30%. After preparation, the sample was removed, cleaned with petroleum ether, and dried.

[0035] Example 3: ZIF67 patterned structures prepared on the substrate surface, as shown in Figure 3. Figure 4 As shown, it has the potential to prepare a variety of patterns and the ability to construct arrays.

[0036] Example 4 Zirconia spheres with a diameter of 0.5 mm were used as the friction pair, and silicon nitride wafers were used as the substrate. A mixture of 5 wt% ZIF-8 (200 nm ~ 1 μm) and 95 wt% PAO4 was used as the lubricant. The substrate surface was ground, polished, cleaned, and dried, and then fixed in a groove directly below the friction pair. 20 μL of lubricant was placed between the friction pair and the substrate material using a pipette. The friction trajectory was set as a straight line. During the friction process, the load was 0.90 N, the sliding speed was 400 μm / s, the reciprocating distance was 200 μm, the friction cycle was 1000 times, the ambient temperature was 85℃, and the relative humidity was 30%. After preparation, the sample was removed, cleaned with petroleum ether, and dried. The obtained ZIF-8 micro / nano structure had a height of approximately 120 nm and a width of approximately 40 μm, with good structural uniformity.

[0037] Example 5 Zirconia spheres with a diameter of 0.5 mm were used as the friction pair, and silicon nitride wafers were used as the substrate. A mixture of 10 wt% HKUST-1 (200 nm ~ 1 μm) and 90 wt% PAO4 was used as the lubricant. The substrate surface was ground, polished, cleaned, and dried, and then fixed in a groove directly below the friction pair. 20 μL of lubricant was placed between the friction pair and the substrate material using a pipette. The friction trajectory was set as a straight line. During the friction process, the load was 0.05 N, the sliding speed was 800 μm / s, the reciprocating distance was 500 μm, the friction cycle was 300 times, the ambient temperature was 95℃, and the relative humidity was 30%. After preparation, the sample was removed, cleaned with petroleum ether, and dried. The obtained HKUST-1 micro / nano structure had a height of approximately 80 nm and a width of approximately 20 μm, with good structural uniformity.

[0038] 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 direct patterning of metal-organic framework materials based on triboprinting, characterized in that, Includes the following steps: The friction pair moves along a set trajectory on the surface of a substrate coated with lubricating printing fluid to form a patterned metal-organic framework micro / nano structure on the substrate surface; the lubricating printing fluid is a dispersion of metal-organic framework material, and the dispersion medium of the dispersion fluid is ethanol or base oil; during the friction movement, the contact load is 0.01~2.0N, and the sliding speed is 100~5000μm / s.

2. The method for direct patterning of metal-organic framework materials based on triboprinting according to claim 1, characterized in that, The metal-organic framework material includes one or more of ZIF-67, ZIF-8, and HKUST-1.

3. The method for direct patterning of metal-organic framework materials based on triboprinting according to claim 1, characterized in that, The base oil includes one or more of PAO4, PAO10 and 500SN.

4. The method for direct patterning of metal-organic framework materials based on triboprinting according to claim 1, 2, or 3, characterized in that, The mass fraction of the metal-organic framework material in the dispersion is 1-20%.

5. The method for direct patterning of metal-organic framework materials based on triboprinting according to claim 1, characterized in that, The frictional motion is a reciprocating frictional motion with a reciprocating distance of 100~2000μm and a reciprocating cycle of 50~5000 times.

6. The method for direct patterning of metal-organic framework materials based on triboprinting according to claim 1 or 5, characterized in that, During the frictional motion, the ambient temperature is 25~150℃ and the relative humidity is 30~40%.

7. The method for direct patterning of metal-organic framework materials based on triboprinting according to claim 1, characterized in that, The friction pair is spherical with a diameter of 0.1~3mm, and the material of the friction pair is ceramic or steel.

8. The method for direct patterning of metal-organic framework materials based on triboprinting according to claim 1, characterized in that, The substrate is made of metal, silicon, ceramic, glass, ITO, polymer, or flexible electronic substrate.

9. The method for direct patterning of metal-organic framework materials based on triboprinting according to claim 1, characterized in that, The patterned metal-organic framework micro / nanostructure has a height of 50-200 nm and a width of 10-50 μm.

10. A system for direct patterning of metal-organic framework materials based on triboprinting, characterized in that, The device includes a friction pair, a substrate, and a lubricating printing fluid. The lubricating printing fluid is a dispersion of a metal-organic framework material, and the dispersion medium of the dispersion is ethanol or a base oil. The lubricating printing fluid is applied between the friction pair and the surface of the substrate.

Images