A mild fluorination modification method of nanomaterials
Patent Information
- Application Number
- CN202610750269.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-28
- Publication Date
- 2026-08-21
AI Technical Summary
[0005]本发明的目的是提供一种纳米材料的温和氟化改性方法，以解决现有氟化技术温和路线氟含量低、依赖含氧官能团，以及高温或高能路线安全风险高的问题
[0020] Compared with existing technologies, this invention provides a mild fluorination modification method for nanomaterials. Through mechanochemical activation combined with deoxyfluorination reaction, the surface fluorine content of nanodiamonds is increased from <1 at.% in traditional liquid-phase fluorination to 5.5-6.5 at.%, achieving high-coverage fluorination modification of the nanodiamond surface. Using an aqueous reaction system, no organic solvents are required; the reaction can be completed simply by ball milling at room temperature. No highly toxic or corrosive reagents are used, making it safe and environmentally friendly, while significantly reducing production costs. Furthermore, it can directly activate the sp³ carbon sites on the nanodiamond surface, enabling not only deoxyfluorination with surface hydroxyl groups but also fluorination grafting at defect sites to form a highly stable CF2 structure. This significantly improves the capacity and stability of the fluorination graft, increasing its thermal oxidation temperature from 460℃ before modification to 610℃.
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Figure CN122608020A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of nanomaterial surface modification technology, and specifically to a mild fluorination modification method for nanomaterials. Background Technology
[0002] Nanodiamonds possess the intrinsic properties of diamond—superhardness, high thermal conductivity, chemical stability, and biocompatibility—as well as the size and surface effects of nanomaterials, making them highly promising for applications in high-end lubrication, polymer composites, biomedicine, electronic devices, and energy storage media. However, native nanodiamonds are rich in oxygen-containing functional groups such as hydroxyl and carboxyl groups, resulting in extremely high surface energy. This makes them prone to severe aggregation in liquid phases and polymer matrices, while also exhibiting poor interfacial compatibility and insufficient environmental stability, significantly limiting their performance and large-scale application. Surface fluorination modification is a core method for controlling the surface chemical state of nanodiamonds. By constructing stable CF covalent bonds on the surface, dangling bonds can be effectively passivated, surface energy reduced, and the dispersion stability, hydrophobicity, thermal stability, and interfacial bonding performance of nanodiamonds significantly improved. This is currently a research hotspot and a key technological bottleneck for the industrial application of functionalized nanodiamonds.
[0003] Currently, the mainstream fluorination modification technologies for nanodiamonds can be divided into five main technical routes: First, using F2 or XeF2 as fluorine sources, surface fluorination is achieved through high-temperature gas-solid direct reaction, which can obtain high fluorine content. However, the reaction conditions are harsh, the fluorine sources used are highly toxic and corrosive, and graphitization of the nanodiamond surface is easily caused at high temperatures, posing extremely high environmental and safety risks and making industrialization difficult. Second, using fluorine-containing gases such as CF4 and SF6 as fluorine sources, active fluorine species are generated through plasma to achieve room temperature to intermediate temperature surface grafting. However, the equipment is expensive, the fluorination uniformity during powder processing is poor, batch stability is insufficient, and it is difficult to scale up production. Third, room temperature selective fluorination is achieved by exciting fluorine reagents with ultraviolet light or electron beams to generate fluorine free radicals. However, the reaction efficiency is low, the excitation source has poor penetration into the powder, and the equipment and operation are complex. The high cost makes it impossible to meet mass production requirements; fourth, using organic fluorine reagents such as DAST and Sulfox Fluor to conduct deoxyfluorination reactions with oxygen-containing functional groups on the surface of nanomaterials in organic solvent systems provides mild reaction conditions, but nanodiamonds are prone to severe aggregation in the liquid phase, and the reaction can only rely on a limited number of oxygen-containing functional groups on the surface, resulting in extremely low fluorine content in the final product, and the use of large amounts of organic solvents does not meet the requirements of green chemistry; fifth, external field enhancement to improve reaction activity through Joule heating, microwaves, mechanical ball milling, etc., but the high energy input can easily damage the crystal structure of nanodiamonds, making process control difficult, unable to balance the fluorine content and fluorination uniformity of the product, and resulting in poor structural retention.
[0004] In summary, existing nanodiamond fluorination technologies suffer from irreconcilable technical contradictions. While high-temperature, plasma, and high-energy-field routes can increase fluorine content to some extent, they also present problems such as high safety risks, high equipment costs, easy structural damage, and difficulty in mass production. Traditional liquid-phase mild fluorination routes, although with mild reaction conditions, suffer from fatal flaws such as poor nanoparticle dispersion, weak reaction activation, high dependence on surface oxygen-containing functional groups, extremely low fluorine content, environmentally unfriendly organic solvents, and limited modification effects. Summary of the Invention
[0005] The purpose of this invention is to provide a mild fluorination modification method for nanomaterials to solve the problems of low fluorine content, dependence on oxygen-containing functional groups, and high safety risks of existing mild fluorination technologies.
[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for mild fluorination modification of nanomaterials, comprising the following steps:
[0007] S1. Add the fluorinating agent Sulfox Fluor and the alkaline activator to the aqueous dispersion of nanomaterials, and mix them evenly to obtain a reaction mixture;
[0008] S2. Transfer the reaction mixture to a ball mill jar, add zirconium oxide ball milling media, and seal the ball mill jar;
[0009] S3. Place the ball milling jar in a planetary ball mill to carry out the ball milling reaction, and complete the fluorination reaction through mechanochemical activation to obtain the fluorinated product;
[0010] S4. Take out the fluorinated product after ball milling, and after washing and drying, obtain fluorinated nanomaterials.
[0011] Furthermore, the nanomaterial is nanodiamond.
[0012] Furthermore, in step S1, the mass concentration of the aqueous dispersion of nanodiamond is 10-16 mg / mL.
[0013] Furthermore, the alkaline activator is DBU.
[0014] Furthermore, in the reaction mixture, the proportions of each raw material are as follows: 5-8 mL of nanomaterial aqueous dispersion, 130-150 mg of Sulfox Fluor, and 50-70 μL of DBU.
[0015] Further, in step S2, the total mass of the zirconia ball milling media is 30-40g; the zirconia balls consist of zirconia balls with a diameter of 10mm and zirconia balls with a diameter of 5mm, wherein the number of 10mm diameter zirconia balls is 5-7, and the remainder is 5mm diameter zirconia balls.
[0016] Furthermore, in step S3, the planetary ball mill has a ball milling speed of 250-350 rpm and a ball milling time of 40-80 min.
[0017] Furthermore, in step S4, the ball milling reaction is carried out in an alternating manner.
[0018] Furthermore, in step S4, the washing process involves repeated washing with ethanol until no white precipitate is produced in the washing solution.
[0019] Furthermore, the fluorinated nanomaterial obtained in step S4 is fluorinated modified nanodiamond with a surface fluorine content of 5.5-6.5 at.%, a stable CF / CF2 covalent bond structure formed on the surface, its crystal phase remains intact and there is no obvious graphitization, and its thermal oxidation temperature is increased from 460℃ before modification to 610℃.
[0020] Compared with existing technologies, this invention provides a mild fluorination modification method for nanomaterials. Through mechanochemical activation combined with deoxyfluorination reaction, the surface fluorine content of nanodiamonds is increased from <1 at.% in traditional liquid-phase fluorination to 5.5-6.5 at.%, achieving high-coverage fluorination modification of the nanodiamond surface. Using an aqueous reaction system, no organic solvents are required; the reaction can be completed simply by ball milling at room temperature. No highly toxic or corrosive reagents are used, making it safe and environmentally friendly, while significantly reducing production costs. Furthermore, it can directly activate the sp³ carbon sites on the nanodiamond surface, enabling not only deoxyfluorination with surface hydroxyl groups but also fluorination grafting at defect sites to form a highly stable CF2 structure. This significantly improves the capacity and stability of the fluorination graft, increasing its thermal oxidation temperature from 460℃ before modification to 610℃. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.
[0022] Figure 1 (a) is the F1s X-ray photoelectron spectrum of the fluorinated modified nanodiamond (F-ND) of the present invention; Figure 1 (b) Fourier transform infrared spectra of unmodified nanodiamond (ND) and fluorinated modified nanodiamond (F-ND) of the present invention;
[0023] Figure 2 Thermogravimetric analysis curves of the unmodified nanodiamond (ND) and the fluorinated modified nanodiamond (F-ND) of this invention are shown.
[0024] Figure 3 The X-ray diffraction patterns are those of the unmodified nanodiamond (ND) and the fluorinated modified nanodiamond (F-ND) of this invention.
[0025] Figure 4 The image shows the transmission electron microscope (TEM) morphology of the fluorinated modified nanodiamond (F-ND) of this invention; wherein, Figure 4 a is a low-magnification transmission electron microscope bright-field image of fluorinated modified nanodiamond; Figure 4 b is a bright-field image of fluorinated modified nanodiamond under medium magnification transmission electron microscopy. Figure 4 c is a high-resolution transmission electron microscope image of fluorinated modified nanodiamonds.
[0026] Figure 5 This is a schematic diagram of the reaction mechanism of the mild fluorination modification method for nanodiamonds of the present invention. Detailed Implementation
[0027] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.
[0028] Example 1:
[0029] This embodiment provides a mild fluorination modification method for nanomaterials, the specific steps of which are as follows:
[0030] S1. Take 6.5 mL of a nanodiamond aqueous dispersion with a mass concentration of 13 mg / mL, add 140 mg of fluorinating agent Sulfox Fluor and 60 μL of alkaline activator DBU to it, stir and mix evenly to obtain a reaction mixture.
[0031] S2. Transfer the above reaction mixture to a planetary ball mill jar, add 35g of zirconia ball milling media, including 6 zirconia balls with a diameter of 10mm and the remainder zirconia balls with a diameter of 5mm, and seal the ball mill jar.
[0032] S3. Place the sealed ball mill jar in a planetary ball mill, set the ball milling speed to 300 rpm, and use an alternating operation mode. The total ball milling time is 60 min. The fluorination reaction is completed through mechanochemical activation to obtain the fluorinated product.
[0033] S4. After ball milling, remove the fluorinated product from the ball milling jar and wash the product repeatedly with anhydrous ethanol until no white precipitate is produced in the washing solution. Dry the washed product to obtain fluorinated modified nanodiamond.
[0034] The product obtained in this embodiment was characterized by testing, and the results are as follows: X-ray photoelectron spectroscopy (XPS) showed that the fluorine content on the product surface was 6.2 at.%, and the F1s spectrum showed that a stable CF and CF2 covalent bond structure was formed on the product surface; X-ray diffraction (XRD) showed that the product maintained a complete diamond crystal phase, and the characteristic diffraction peaks were consistent with those of unmodified nanodiamonds, with no obvious graphitization characteristic peaks appearing; transmission electron microscopy (TEM) showed that the product particles were uniformly dispersed and the fluorine element was uniformly distributed; thermogravimetric analysis showed that the thermal oxidation temperature of the product was 608℃, which was significantly higher than the 460℃ of unmodified nanodiamonds.
[0035] Example 2:
[0036] This embodiment provides a mild fluorination modification method for nanomaterials, the specific steps of which are as follows:
[0037] S1. Take 5 mL of a nano-diamond aqueous dispersion with a mass concentration of 10 mg / mL, add 130 mg of fluorinating agent Sulfox Fluor and 50 μL of alkaline activator DBU to it, stir and mix evenly to obtain a reaction mixture.
[0038] S2. Transfer the above reaction mixture to a planetary ball mill jar, add 30g of zirconia ball milling media, including 5 zirconia balls with a diameter of 10mm and the remainder zirconia balls with a diameter of 5mm, and seal the ball mill jar.
[0039] S3. Place the sealed ball mill jar in a planetary ball mill, set the ball milling speed to 250 rpm, and use an alternating operation mode. The total ball milling time is 40 min. The fluorination reaction is completed through mechanochemical activation to obtain the fluorinated product.
[0040] S4. After ball milling, remove the fluorinated product from the ball milling jar and wash the product repeatedly with anhydrous ethanol until no white precipitate is produced in the washing solution. Dry the washed product to obtain fluorinated modified nanodiamond.
[0041] The product obtained in this embodiment was tested and characterized, and the results are as follows: the fluorine content on the surface of the product is 5.6 at.%, and a stable CF / CF2 covalent bond structure is formed on the surface; the diamond crystal phase remains intact and there is no obvious graphitization; the particles are uniformly dispersed, and the thermal oxidation temperature is 595℃.
[0042] Example 3:
[0043] This embodiment provides a mild fluorination modification method for nanomaterials, the specific steps of which are as follows:
[0044] S1. Take 8 mL of a nanodiamond aqueous dispersion with a mass concentration of 16 mg / mL, add 150 mg of fluorinating agent Sulfox Fluor and 70 μL of alkaline activator DBU to it, stir and mix evenly to obtain a reaction mixture.
[0045] S2. Transfer the above reaction mixture to a planetary ball mill jar, add 40g of zirconia ball milling media, including 7 zirconia balls with a diameter of 10mm and the remainder zirconia balls with a diameter of 5mm, and seal the ball mill jar.
[0046] S3. Place the sealed ball mill jar in a planetary ball mill, set the ball milling speed to 350 rpm, and use an alternating operation method. The total ball milling time is 80 min. The fluorination reaction is completed through mechanochemical activation to obtain the fluorinated product.
[0047] S4. After ball milling, remove the fluorinated product from the ball milling jar and wash the product repeatedly with anhydrous ethanol until no white precipitate is produced in the washing solution. Dry the washed product to obtain fluorinated modified nanodiamond.
[0048] The product obtained in this embodiment was tested and characterized, and the results are as follows: the fluorine content on the surface of the product is 6.4 at.%, and a stable CF / CF2 covalent bond structure is formed on the surface; the diamond crystal phase remains intact and there is no obvious graphitization; the particles are uniformly dispersed, and the thermal oxidation temperature is 610℃.
[0049] The reaction principle of this invention is as follows: The alkaline activator DBU activates the hydroxyl groups on the surface of nanodiamonds, causing the fluorinating reagent Sulfox Fluor to undergo a deoxyfluorination reaction with the hydroxyl groups, forming CF bonds on the nanodiamond surface. Simultaneously, the mechanical energy generated during ball milling introduces defect sites onto the nanodiamond surface, achieving a defect-driven fluorination reaction that can directly activate sp. 3 By using carbon sites, the traditional liquid-phase fluorination method, which relies solely on oxygen-containing functional groups, is able to generate stable CF / CF2 covalent structures on the surface of nanodiamonds without damaging the main crystal lattice of the diamond, thus achieving highly efficient fluorination modification with high structure preservation.
[0050] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.
Claims
1. A mild fluorination modification method for nanomaterials, characterized in that, Includes the following steps: S1. Add the fluorinating agent Sulfox Fluor and the alkaline activator to the aqueous dispersion of nanomaterials, and mix them evenly to obtain a reaction mixture; S2. Transfer the reaction mixture to a ball mill jar, add zirconium oxide ball milling media, and seal the ball mill jar; S3. Place the ball milling jar in a planetary ball mill to carry out the ball milling reaction, and complete the fluorination reaction through mechanochemical activation to obtain the fluorinated product; S4. Take out the fluorinated product after ball milling, and after washing and drying, obtain fluorinated nanomaterials.
2. The mild fluorination modification method for nanomaterials according to claim 1, characterized in that, The nanomaterial is nanodiamond.
3. The mild fluorination modification method for nanomaterials according to claim 2, characterized in that, In step S1, the mass concentration of the aqueous dispersion of nanodiamond is 10-16 mg / mL.
4. The mild fluorination modification method for nanomaterials according to claim 1, characterized in that, The alkaline activator is DBU.
5. The mild fluorination modification method for nanomaterials according to claim 1, characterized in that, The proportions of each raw material in the reaction mixture are as follows: 5-8 mL of aqueous dispersion of nanomaterials, 130-150 mg of Sulfox Fluor, and 50-70 μL of DBU.
6. The mild fluorination modification method for nanomaterials according to claim 1, characterized in that, In step S2, the total mass of the zirconia ball milling media is 30-40g; the zirconia balls consist of zirconia balls with a diameter of 10mm and zirconia balls with a diameter of 5mm, wherein the number of 10mm diameter zirconia balls is 5-7, and the remainder is 5mm diameter zirconia balls.
7. The mild fluorination modification method for nanomaterials according to claim 1, characterized in that, In step S3, the ball milling speed of the planetary ball mill is 250-350 rpm, and the ball milling time is 40-80 min.
8. The mild fluorination modification method for nanomaterials according to claim 1, characterized in that, In step S4, the ball milling reaction is carried out in an alternating manner.
9. The mild fluorination modification method for nanomaterials according to claim 1, characterized in that, In step S4, the washing process involves repeated washing with ethanol until no white precipitate is produced in the washing solution.
10. The mild fluorination modification method for nanomaterials according to claim 1, characterized in that, The fluorinated nanomaterial obtained in step S4 is fluorinated modified nanodiamond with a surface fluorine content of 5.5-6.5 at.%, a stable CF / CF2 covalent bond structure on the surface, and its crystal phase remains intact without obvious graphitization. Its thermal oxidation temperature is increased from 460℃ before modification to 610℃.