Liquid metal magnetofluid and preparation method of magnetic liquid metal micro-nano particles

Abstract

The invention relates to the technical field of alloy materials, in particular to a liquid metal magnetofluid and a preparation method of magnetic liquid metal micro-nano particles. The preparation method of the liquid metal magnetic fluid and the magnetic liquid metal micro-nano particles is easy and convenient to operate, easy to execute, short in preparation time and good in process stability. The whole process of preparing the liquid metal magnetofluid by using the vortex method only needs about 20 minutes, the obtained liquid metal magnetofluid can be continuously used for preparing the magnetic liquid metal micro-nano particles by using the vortex method, the preparation of the magnetic liquid metal micro-nano particles does not exceed 20 minutes, and the production efficiency is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of alloy materials, and in particular to a method for preparing a liquid metal magnetic fluid and magnetic liquid metal micro-nano particles. Background Art

[0002] Liquid metal magnetic fluids are different from traditional magnetic fluids that use water, oil or organic solvents as carriers. They have excellent conductivity, high density, high boiling point and chemical stability, which greatly expands the functions of magnetic fluids. Gallium-based magnetic liquid metal micro-nanoparticles have good biocompatibility, magnetic response, acoustic, optical, thermal and electrical stimulus response, fluidity and modifiability. Liquid metal magnetic fluids and magnetic liquid metal micro-nanoparticles exhibit multiple functions and can be widely used in biomedical engineering, thermal management, printing, patterning, flexible sensors and soft robots.

[0003] In the prior art, mechanical stresses such as grinding (Elbourne A, Cheeseman S, Atkin P, et al. Antibacterial Liquid Metals: Biofilm Treatment via Magnetic Activation [J]. ACS Nano, 2020, 14 (1): 802-17) or solvents such as hydrochloric acid (Tang J, Zhao X, Li J, et al. Liquid Metal Phagocytosis: Intermetallic Wetting Induced Particle Internalization [J]. Advanced Science, 2017, 4 (5): 1700024) are used to achieve intermetallic infiltration and prepare liquid metal magnetic fluid. Mechanical stimulation methods such as grinding usually place liquid metal and magnetic particles in an inert environment, remove the oxides of the two substances through mechanical shear stress, make them in direct contact, trigger the liquid metal engulfment process, and promote the formation of liquid metal magnetic fluid. However, the preparation process of the grinding method is cumbersome, and there are characteristics of low manufacturing efficiency and low filling ratio of magnetic particles. The solvent preparation method usually immerses the liquid metal and magnetic particles in a solution such as hydrochloric acid and stirs them, followed by rinsing and vacuum drying to prepare the liquid metal magnetic fluid. The solution is used to remove the oxide, so that the magnetic particles and liquid metal contact each other, triggering the engulfment process and the formation of liquid metal magnetic fluid. This preparation method is cumbersome and the filling ratio of magnetic particles is also limited. For example, when using an acidic solution such as hydrochloric acid, hydrochloric acid will react with liquid metal and magnetic particles such as iron, resulting in raw material loss; and the hydrogen produced in the process will hinder the contact between magnetic particles and liquid metal, affecting the formation of liquid metal magnetic fluid. When using alkaline or neutral solutions for preparation, additional steps are required, such as polarization or the use of sacrificial metals to electrochemically reduce liquid metals and magnetic particles, and the process is quite cumbersome. The prepared liquid metal magnetic fluid can be dispersed into micro-nano structures by ultrasound to become magnetic liquid metal micro-nano particles. However, as the filling ratio of magnetic particles increases, the liquid metal magnetic fluid exhibits a harder texture, and the ultrasound method may not be sufficient to disperse it into a micro-nano structure. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a method for preparing a liquid metal magnetic fluid and magnetic liquid metal micro-nano particles to solve the following technical problems:

[0005] 1. The problem of low filling ratio of magnetic particles in liquid metal magnetic fluid;

[0006] 2. The complex preparation process of liquid metal magnetic fluid and magnetic liquid metal micro-nano particles;

[0007] 3. The ultrasonic method is not suitable for dispersing liquid metal magnetic fluids with high magnetic particle filling ratios.

[0008] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0009] In a first aspect, a method for preparing a liquid metal magnetic fluid is provided, which comprises the following steps: adding magnetic particles into liquid metal, and obtaining the liquid metal magnetic fluid by a vortex mixing method.

[0010] Furthermore, the magnetic particles are reduced iron powder, or ferrosoferric oxide nanoparticles.

[0011] Furthermore, the liquid metal is gallium, or a binary alloy of gallium and indium, or a ternary alloy of gallium, indium, and tin.

[0012] Furthermore, the mass ratio of the magnetic particles to the liquid metal is (0.1-5):5.

[0013] Furthermore, the vortex mixing has a vortex time of 5-25 minutes and a rotation speed of 1000-20000 rpm.

[0014] On the other hand, a method for preparing magnetic liquid metal micro-nano particles is provided, wherein liquid metal magnetic fluid is added to a dispersion liquid, and a solution containing magnetic liquid metal micro-nano particles of different sizes is obtained by a vortex dispersion method, and then the solution is filtered and screened to obtain magnetic liquid metal micro-nano particles of a specific size.

[0015] Furthermore, the dispersion liquid is a chitosan oligosaccharide solution or pure water.

[0016] Furthermore, the mass ratio of the liquid metal magnetic fluid to the dispersion liquid is (0.1-5):5.

[0017] Furthermore, the vortex dispersion has a vortex time of 1-5 minutes and a rotation speed of 8000-10000 rpm.

[0018] The beneficial effects of the present invention are:

[0019] 1. The preparation method of the liquid metal magnetic fluid and magnetic liquid metal micro-nano particles provided by the present invention is simple to operate, easy to execute, short in preparation time, and good in process stability. It only takes about 20 minutes to prepare the liquid metal magnetic fluid using the vortex method, and the obtained liquid metal magnetic fluid can continue to use the vortex method to prepare magnetic liquid metal micro-nano particles. The preparation of magnetic liquid metal micro-nano particles does not exceed 20 minutes, which greatly improves production efficiency.

[0020] 2. The preparation method of the liquid metal magnetic fluid and magnetic liquid metal micro-nano particles provided by the present invention involves only a few types of raw materials, namely, liquid metal, magnetic particles and dispersion liquid, which reduces raw material consumption and production costs; at the same time, it reduces the use of harmful chemicals (such as hydrochloric acid, etc.) and reduces operational risks.

[0021] 3. The liquid metal magnetic fluid preparation method provided by the present invention can be used to prepare liquid metal magnetic fluid with a higher magnetic particle filling ratio; the magnetic liquid metal micro-nano particle preparation method provided can screen magnetic liquid metal micro-nano particles of different particle sizes by adjusting the vortex time and the size of the filter membrane to meet different needs.

[0022] 4. The vortex preparation method provided by the present invention solves the problem that the ultrasonic method is difficult to effectively disperse the liquid metal magnetic fluid with a high magnetic particle filling ratio (φ≥44.4%). BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart for preparing the liquid metal magnetic fluid of Example 1;

[0024] Figure 2 Macroscopic images of liquid metal magnetic fluids with different magnetic particle filling ratios prepared in Example 1;

[0025] Figure 3 This is the magnetic response image of the liquid metal magnetic fluid with a magnetic particle filling ratio of 44.4% prepared in Example 1;

[0026] Figure 4 This is a flow chart for preparing magnetic liquid metal micro-nano particles of Example 2;

[0027] Figure 5 This is a diagram showing the characterization results of the magnetic liquid metal micro-nanoparticles prepared in Example 2. DETAILED DESCRIPTION

[0028] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0029] Example 1

[0030] This embodiment follows Figure 1 The process shown in the figure is to prepare a liquid metal magnetic fluid, and the specific steps are as follows:

[0031] (1) Weigh 2 g of pure gallium into a 5 mL centrifuge tube, and then add 0.4, 0.8, 1.2, 1.6, and 2.0 g of reduced iron powder, respectively.

[0032] (2) Use a magnet to attract the iron powder to the bottom of the bottle and mix it initially.

[0033] (3) The magnetic particles and the liquid metal were vortex-mixed at a rotation speed of 9000 rpm for 15 minutes (VortexGenie2 vortex mixer, single test tube head gasket) to obtain liquid metal magnetic fluid.

[0034] The filling ratio of magnetic particles in the liquid metal magnetic fluid can be 0-50%. When the filling ratio of magnetic particles is low, no magnetism is exhibited. When the filling ratio of magnetic particles is high, there is no fluidity. The filling ratios of magnetic particles in the liquid metal magnetic fluid prepared in Example 1 are 16.7%, 28.6%, 37.5%, 44.4% and 50% respectively (the filling ratio of magnetic particles φ = the mass of magnetic particles / the mass of liquid metal magnetic fluid × 100%). Figure 2 Macroscopic images of liquid metal magnetic fluid with different magnetic particle filling ratios. Figure 3 Magnetic response image of liquid metal magnetic fluid with a magnetic particle filling ratio of 44.4%.

[0035] Example 2

[0036] This embodiment follows Figure 4 The process shown is to prepare a magnetic liquid metal micro-nano particle, and the specific steps are as follows:

[0037] (1) Prepare a 40 mg / mL chitosan oligosaccharide solution and transfer 10 mL into a 50 mL centrifuge tube.

[0038] (2) 3.6 g of liquid metal magnetic fluid (magnetic particle filling ratio is 44.4%) is added to the chitosan oligosaccharide solution.

[0039] (3) The mixture was vortexed at 9000 rpm for 3 minutes (Vortex Genie 2 vortex mixer, single tube head gasket).

[0040] (4) Using a 100 μm cell sieve to filter the vortexed mixture to remove magnetic particles with a particle size greater than 100 μm; then using a 40 μm cell sieve to filter to remove magnetic particles with a particle size less than 40 μm, magnetic liquid metal micro-nanoparticles with a particle size between 40 and 100 μm can be obtained.

[0041] The characterization results of the magnetic liquid metal micro-nano particles prepared in Example 2 are as follows: Figure 5 , scale: 25μm. Elemental analysis shows that the magnetic liquid metal micro-nano particles are successfully prepared.

[0042] In summary, the present invention can optimize the hardness, fluidity and magnetism of the liquid metal magnetic fluid by adjusting the filling ratio of the magnetic particles, so as to make it suitable for different application scenarios. The method for preparing the magnetic liquid metal micro-nano particles provided by the present invention can disperse the obtained liquid metal magnetic fluid into a micro-nano structure, which is used to supplement the demand for magnetic liquid metal micro-nano particles.

[0043] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for preparing a liquid metal magnetic fluid, characterized in that: The method comprises the following steps: adding magnetic particles into liquid metal, and obtaining liquid metal magnetic fluid by vortex mixing.

2. The method for preparing the liquid metal magnetic fluid according to claim 1, characterized in that: The magnetic particles are reduced iron powder or ferroferric oxide nanoparticles.

3. The method for preparing the liquid metal magnetic fluid according to claim 1, characterized in that: The liquid metal is gallium, or a binary alloy of gallium and indium, or a ternary alloy of gallium, indium, and tin.

4. The method for preparing the liquid metal magnetic fluid according to claim 1, characterized in that: The mass ratio of magnetic particles to liquid metal is (0.1-5):

5.

5. The method for preparing the liquid metal magnetic fluid according to claim 1, characterized in that: The vortex time is 5-25 minutes and the rotation speed is 1000-20000 rpm.

6. A method for preparing magnetic liquid metal micro-nano particles, characterized in that: A liquid metal magnetic fluid is prepared by the method described in any one of claims 1 to 5, and then the liquid metal magnetic fluid is added to a dispersion liquid, and a solution containing magnetic liquid metal micro-nano particles of different sizes is obtained by a vortex dispersion method, and then filtered and screened to obtain magnetic liquid metal micro-nano particles of a specific size.

7. The method for preparing magnetic liquid metal micro-nano particles according to claim 6, characterized in that: The dispersion liquid is chitosan oligosaccharide solution or pure water.

8. The method for preparing magnetic liquid metal micro-nano particles according to claim 7, characterized in that: The mass ratio of liquid metal magnetic fluid to dispersion liquid is (0.1-5):

5.

9. The method for preparing magnetic liquid metal micro-nano particles according to claim 6, characterized in that: The vortex time is 1-5 minutes and the rotation speed is 8000-10000 rpm.

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