A functional surface modifier, modified material and modification method thereof

Abstract

This invention belongs to the field of material surface modification, and relates to a novel functional surface modifier, the modified material obtained by modification, and the modification method. This invention points out that substances containing liquid metal can be used as surface modifiers. Specifically, it indicates that substances containing liquid metal can serve as surface modifiers for materials (including fillers), improving material functionality such as conductivity, dielectric properties, magnetic permeability, thermal conductivity, photothermal properties, and medical applications, while also improving the dispersibility of related materials in composite materials. This invention achieves functional modification of materials (including fillers) through a simple "one-step method," without solvents or byproducts, and requiring no post-processing. It is a simple, versatile, and advanced technology. The introduction of a small amount of liquid metal solves the problem that traditional surface modification methods cannot provide functional gains, while simultaneously improving filler dispersion.

Description

Technical Field

[0001] This invention belongs to the field of material surface modification, and relates to a novel functional surface modifier, the modified material obtained by modification, and the modification method. Background Technology

[0002] Composite materials are widely used in transportation, construction, electronics, power, and energy sectors. In these applications, surface modification of the filler particles is often necessary to achieve good filler dispersion and interfacial adhesion, thereby improving the composite's properties. However, traditional surface modification methods, such as plasma treatment, surface oxidation, phosphate ester modification, silane coupling agent treatment, dopamine treatment, and surface grafting, while enhancing the mechanical properties (strength and modulus) of composite materials, offer very limited gains in the electrical, magnetic, thermal, acoustic, and optical functions. This fails to meet the increasingly diverse functional material demands of the electronics, power, energy, and environmental sectors.

[0003] This is mainly because the intrinsic functionality (electric, magnetic, thermal, acoustic and optical) of traditional organic modified layers (organic molecules and groups) is poor. The function is hindered or even passivated in the cross-interface transfer between filler / matrix, so the functionality of the composite material hardly changes after modification, and sometimes it is even weakened (such as the conductivity and dielectric constant in polymer composites).

[0004] Modifying the filler surface with a functionally prominent second component (such as metallic or inorganic ceramic materials) holds promise for solving this problem. This typically requires techniques such as deposition and electrostatic assembly, which, while capable of enhancing functionality, lack versatility and modification efficiency for the filler, and also fail to improve filler dispersion.

[0005] In summary, few surface modification methods can simultaneously solve the problems of filler function and dispersion, and also have good versatility and scalability. Summary of the Invention

[0006] To address the existing problems in the field of filler surface modification, the purpose of this invention is to provide a more universal functional surface modifier, its modification method, and the modified material obtained therefrom. This invention uses a substance containing liquid metal (liquid metal refers to a wide range of low-melting-point metal materials that are liquid at room temperature or lower temperatures, possessing intrinsic electrical, dielectric, thermal, and photothermal properties, and exhibiting weak interactions with fillers such as metals and inorganic ceramics) to modify the surface of materials (such as fillers). The modification method is a mechanical forced mixing method. Through the strong shear force and pressure induced by the strong mechanical mixing of the solid phase, a strong mechanochemical effect is generated, causing a strong interfacial interaction between the liquid metal and the material (initial filler), thereby achieving the fixation of the material by the liquid metal. The resulting liquid metal modified material can improve the dispersibility of materials such as fillers while enhancing their functionality (conductivity, dielectricity, magnetic permeability, thermal conductivity, photothermal properties, medical applications, etc.). This is a significantly different approach from traditional surface modification. This surface modification is completed in a "one-step" process, without solvents or byproducts, and requires no post-processing. It is a new technology that is simple to produce and highly versatile.

[0007] The technical solution of this invention:

[0008] The first technical problem this invention aims to solve is to identify substances containing liquid metal as surface modifiers. Specifically, it aims to identify substances containing liquid metal that can serve as surface modifiers for materials (including fillers), improving both the functionality (conductivity, dielectric properties, magnetic permeability, thermal conductivity, photothermal properties, medical applications, etc.) and the dispersibility of these materials when used in composite materials.

[0009] Furthermore, the liquid metal substance is used as a surface modifier for the filler.

[0010] Furthermore, when the liquid metal-containing substance is used as a surface modifier for fillers, the specific method is as follows: the liquid metal-containing substance is added to the filler, and then a mechanical mixing process is used to obtain the corresponding modified filler; wherein, the volume ratio of the liquid metal-containing substance to the filler is: 85.00 to 99.99 parts by volume of filler and 15.00 to 0.01 parts by volume of liquid metal.

[0011] Furthermore, the liquid metal-containing substance is used to improve the dispersibility of the filler in the material, such as in polymer materials, inorganic ceramic materials, or other liquid materials (e.g., small molecule solvents and ionic liquids).

[0012] Furthermore, substances containing liquid metal are used to improve the functional properties of fillers, such as electrical conductivity, dielectric properties, electromagnetic properties, thermal conductivity, photothermal properties, or rheological tensile properties.

[0013] Furthermore, the mechanical mixing process involves using shear forces (e.g., grinding equipment with a rotation speed > 60 rpm, stirring equipment with a rotation speed > 600 rpm, and the distance between the mixing rod and the mixing equipment wall < 2 cm) and pressure-induced physicochemical effects during mixing to modify the filler with liquid metal. The modification process requires no auxiliary media or post-treatment; the product of this one-step strong mechanical mixing is the liquid metal-modified filler.

[0014] Furthermore, the equipment used in the mechanical mixing processing method is selected from: high-speed mixers, ribbon mixers, plow mixers, zero-gravity mixers, cone mixers, automatic grinders, automatic ball mills or sand mills, and other equipment with strong mechanical mixing, or a combination of the above mixing equipment.

[0015] Furthermore, the liquid metal-containing substance includes at least one of gallium, indium, zirconium, rubidium, francium, cesium, tin, or bismuth, or it may be a liquid metal that has been modified twice or multiple times through other modification methods such as chemical reduction, chemical oxidation, silane coupling agent grafting, dopamine polymerization, doping, etc.

[0016] Furthermore, the filler is selected from: ceramic materials, metal materials, carbon-based materials, etc., or it can be the above-mentioned fillers after other surface modifications, such as acid-treated metals, hydrogen peroxide-treated ceramics and graphite oxide, or combinations of the above-mentioned fillers, such as a combination of carbon-based graphite oxide and ceramic-based hexagonal boron nitride.

[0017] Furthermore, the ceramic material is aluminum oxide, magnesium oxide, zinc oxide, titanium dioxide, ferric oxide, iron tetroxide, vanadium pentoxide, silicon dioxide, nickel hydroxide, calcium carbonate, montmorillonite, mica, bentonite, boron nitride, silicon carbide, aluminum nitride, silicon nitride, barium titanate, barium zirconate titanate, barium strontium titanate, Mxene, or molybdenum disulfide, etc.

[0018] Furthermore, the metallic material is a structural material metal or a functional material metal such as copper, iron, nickel, silver, magnesium, zinc, tungsten, lithium, sodium, manganese, stainless steel, rubidium iron boron or samarium cobalt.

[0019] Furthermore, the carbon-based materials include expanded graphite, graphene oxide, and carbon nanotubes.

[0020] Furthermore, the morphology of the filler includes 0-dimensional particles, 1-dimensional fibers, 2-dimensional sheets, and 3-dimensional complex shapes.

[0021] Furthermore, the initial filler size ranges from 1.0 nm to 1.0 cm, and can be either a monodisperse filler or a polydisperse filler, such as spherical alumina fillers with size composites used in the thermal management field.

[0022] Furthermore, the modification process temperature is selected below the melting point of the liquid metal substance to maintain good fluidity of the liquid metal and enable it to be more evenly dispersed on the filler. For example, when using gallium indium tin, the mixing temperature should be above 20°C.

[0023] Furthermore, the mixing time of the mechanical force is 0.01h to 10.00h, and the time can be appropriately shortened for mixing equipment with high rotation speed.

[0024] Furthermore, the magnitude of the mechanical force can be controlled by adjusting the distance between the stirring rod (stirring blade, stirring ball) and the equipment wall. The closer the stirring rod is to the equipment wall, the greater the lateral pressure that can be applied to the modified filler. Choosing a stirring rod (blade, ball) with a larger modulus helps reduce force dissipation and enhance the modification effect; for example, steel blades are superior to plastic blades. In addition, significantly increasing the stirring and mixing speed can also increase the shear force during modification.

[0025] Furthermore, the modified atmosphere can be selected from air, oxygen, nitrogen, or an inert gas.

[0026] The second technical problem to be solved by the present invention is to provide a method for improving the dispersibility of fillers in a polymer matrix. The method comprises: modifying the filler with a substance containing liquid metal; preparing the modified filler by mechanically mixing the filler and the substance containing liquid metal; and then adding the obtained modified filler to the polymer matrix to improve the dispersibility of the filler in the matrix; wherein the volume ratio of the substance containing liquid metal to the filler is: 85.00-99.99 parts by volume of filler and 15.00-0.01 parts by volume of liquid metal.

[0027] Further, the volume ratio of the modified filler to the polymer matrix is: 0.01 to 99.00 parts by volume of modified filler and 99.99 to 1.00 parts by volume of polymer matrix. Preferably, it is: 1 to 99 parts by volume of modified filler and 99 to 1 part by volume of polymer matrix.

[0028] Furthermore, the filler is selected from: ceramic materials, metal materials, carbon-based materials, etc., or it can be the above-mentioned fillers after other surface modifications, such as acid-treated metals, hydrogen peroxide-treated ceramics and graphite oxide, or combinations of the above-mentioned fillers, such as a combination of carbon-based graphite oxide and ceramic-based hexagonal boron nitride.

[0029] The third technical problem to be solved by the present invention is to provide a modified material, which is prepared by the following method: adding a substance containing liquid metal to a filler, and then obtaining the corresponding modified filler by mechanical mixing; wherein the volume ratio of the substance containing liquid metal to the filler is: 85.00 to 99.99 parts by volume of filler and 15.00 to 0.01 parts by volume of liquid metal.

[0030] Furthermore, the liquid metal-containing substance includes at least one of gallium, indium, zirconium, rubidium, francium, cesium, tin, or bismuth, or it may be a liquid metal that has been modified twice or multiple times through other modification methods such as chemical reduction, chemical oxidation, silane coupling agent grafting, dopamine polymerization, doping, etc.

[0031] Furthermore, the filler is selected from: ceramic materials, metal materials, carbon-based materials, etc., or it can be the above-mentioned fillers after other surface modifications, such as acid-treated metals, hydrogen peroxide-treated ceramics and graphite oxide, or combinations of the above-mentioned fillers, such as a combination of carbon-based graphite oxide and ceramic-based hexagonal boron nitride.

[0032] Furthermore, the morphology of the modified material (liquid metal anchored on the material) can be fully encapsulated (core-shell structure), partially encapsulated (protruding structure), overlapped (bridging structure), and double-yolk (liquid metal simultaneously encapsulates multiple fillers).

[0033] Furthermore, the liquid metal modified filler can undergo secondary or multiple modifications after modification, such as oxidation or reduction of the filler body or liquid metal part, grafting of silane coupling agent, polymerization of dopamine, or alloying of liquid metal.

[0034] Furthermore, the modified material contains very little liquid metal, and the filler is the main component. This is significantly different from traditional liquid metal / filler hybrid materials. Only a small amount of liquid metal is fixed on the surface of the modified filler. The volume ratio of the initial filler to the liquid metal is: 85.00 to 99.99 parts by volume of initial filler and 15.00 to 0.01 parts by volume of liquid metal.

[0035] Preferably, in the modified material, the liquid metal-containing substance is gallium indium tin liquid metal, and the filler is at least one of barium titanate, barium zirconate titanate, barium strontium titanate, Mxene, or molybdenum disulfide; the resulting modified material has a high dielectric constant.

[0036] Preferably, in the modified material, the liquid metal-containing substance is gallium indium tin liquid metal, and the filler is at least one of the following: aluminum oxide, magnesium oxide, zinc oxide, titanium dioxide, ferric oxide, ferric oxide, vanadium pentoxide, silicon dioxide, nickel hydroxide, calcium carbonate, montmorillonite, mica, bentonite, boron nitride, silicon carbide, aluminum nitride, silicon nitride, barium titanate, barium zirconate titanate, barium strontium titanate, Mxene, or molybdenum disulfide; the resulting modified material has high electromagnetic shielding performance.

[0037] The fourth technical problem to be solved by the present invention is to provide a method for improving the dielectric constant of filler, wherein the method is as follows: modifying the filler with a substance containing liquid metal, and preparing the modified filler by mechanically mixing the filler and the substance containing liquid metal; wherein the volume ratio of the substance containing liquid metal to the filler is 0.01~15.00:99.99~85.00.

[0038] Furthermore, the filler is selected from at least one of barium titanate, barium zirconate titanate, barium strontium titanate, Mxene, or molybdenum disulfide.

[0039] The fifth technical problem to be solved by the present invention is to provide a method for improving the electromagnetic shielding performance of filler, wherein the method is as follows: modifying the filler with a substance containing liquid metal, and preparing the modified filler by mechanically mixing the filler and the substance containing liquid metal; wherein the volume ratio of the substance containing liquid metal to the filler is 0.01~15.00:99.99~85.00.

[0040] Furthermore, the filler is selected from at least one of the following: alumina, magnesium oxide, zinc oxide, titanium dioxide, ferric oxide, ferric oxide, vanadium pentoxide, silicon dioxide, nickel hydroxide, calcium carbonate, montmorillonite, mica, bentonite, boron nitride, silicon carbide, aluminum nitride, silicon nitride, barium titanate, barium zirconate titanate, barium strontium titanate, Mxene, or molybdenum disulfide.

[0041] The sixth technical problem to be solved by the present invention is to provide an amphiphilic filler, wherein the raw materials of the amphiphilic filler include a filler and a surface modifier, wherein the surface modifier is a substance containing liquid metal; the volume ratio of the liquid metal-containing substance to the filler is 0.01-15.00: 99.99-85.00; wherein the filler is alumina, magnesium oxide, zinc oxide, titanium dioxide, ferric oxide, ferric oxide, vanadium pentoxide, silicon dioxide, nickel hydroxide, calcium carbonate, montmorillonite, mica, bentonite, boron nitride, silicon carbide, aluminum nitride, silicon nitride, barium titanate, barium zirconate titanate, barium strontium titanate, Mxene, expanded graphite, graphene oxide, carbon nanotubes, copper, iron, nickel, silver, magnesium, zinc, tungsten, lithium, sodium, manganese, stainless steel, rubidium iron boron, or samarium cobalt.

[0042] The seventh technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned amphiphilic filler, wherein the preparation method is as follows: the filler and the surface modifier are mixed by mechanical force to obtain the corresponding modified filler; wherein the volume ratio of the surface modifier to the filler is: 0.01~15.00: 99.99~85.00.

[0043] The beneficial effects of this invention are:

[0044] This invention achieves functional modification of materials (including fillers) through a simple "one-step method" without solvents or byproducts and without post-processing. It is a new technology that is easy to produce and highly versatile. The introduction of a small amount of liquid metal not only solves the problem that traditional surface modification methods cannot provide functional gains, but also has the potential to improve the dispersion of fillers.

[0045] This invention is the first to demonstrate that liquid metal-like materials (substances containing liquid metal) can be used as surface modifiers for materials. By employing a strong mechanical mixing process involving "mechanically induced strong interactions" with the material, a modified material with a structure of "a small amount of liquid metal anchored to the filler surface" is obtained. The resulting modified material is particularly suitable as a raw material for fields such as electronics, electromagnetics, electricity, energy, photothermal, environment, and biomedicine. In applications, the modified material can be used directly as a raw material, assembled and sintered as a framework, prepared as a dispersion, scaled up for surface modification of macroscopic bulk materials, or directly added to a matrix material (polymers, ceramics, and metals, etc.) to create composite materials. Attached image description:

[0046] Figure 1 Scanning electron microscopy morphology and elemental distribution of the liquid metal modified alumina filler (LM-Al2O3) with a liquid metal content of 4.0 vol% in Example 1 and the liquid metal modified boron nitride filler (LM-BN) in Example 3, prepared by strong shear mechanical forced mixing.

[0047] Figure 2 a represents the change in the dielectric constant (1 kHz) of LM-BaTiO3 with the liquid metal content in Example 2. Figure 2 b represents the change in electromagnetic shielding efficiency of LM-Al2O3 with the liquid metal content in Example 1.

[0048] Figure 3 The images show the changes in hydrophilicity (wetting of H2O) and lipophilicity (wetting of diiodomethane, abbreviated as CH2I2) of gallium indium tin liquid metal modified barium titanate (LM-BaTiO3) in Example 2 with varying liquid metal content; and a comparison with silane-modified barium titanate (Silane-BaTiO3) obtained in Comparative Example 3 and dopamine-modified barium titanate (PDA-BaTiO3) obtained in Comparative Example 4.

[0049] Figure 4 a represents the change in contact angle of gallium indium tin liquid metal modified barium titanate (LM-BaTiO3) with varying liquid metal content in Example 2; Figure 4 b is a comparison of Example 2 with silane modification (Comparative Example 3) and dopamine modification (Comparative Example 4).

[0050] Figure 5 The images show the changes in hydrophilicity (wetting of H2O) and lipophilicity (wetting of diiodomethane, abbreviated as CH2I2) of the gallium indium tin liquid metal modified boron nitride filler (LM@BN) in Example 5.

[0051] Figure 6 The scanning electron microscope cross-sectional morphology of the polymer composites prepared with polypropylene (PP), polymethyl methacrylate (PMMA) and polyvinylidene fluoride (PVDF) before and after liquid metal modification in Examples 5 and Comparative Example 5 shows the improved filler dispersion due to liquid metal modification.

[0052] Figure 7 The scanning electron microscope cross-sectional morphology of the polymer composites prepared by BaTiO3 before and after liquid metal modification with polyvinylidene fluoride (PVDF) in Example 6 and Comparative Example 6 shows the improved filler dispersion due to liquid metal modification.

[0053] Figure 8 The scanning electron microscope cross-sectional morphology of the polymer composites prepared with polydimethylsiloxane (PDMS) before and after liquid metal modification of alumina filler in Example 7 and Comparative Example 7 shows the improved filler dispersion due to liquid metal modification.

[0054] Figure 9 The scanning electron microscope cross-sectional morphology of the polymer composites prepared by NdFeB and polyvinylidene fluoride (PVDF) before and after liquid metal modification in Example 8 and Comparative Example 8 shows the improved filler dispersion due to liquid metal modification.

[0055] Figure 10 This is a comparison of the macroscopic rheological properties of the composite materials obtained in Example 7 and Comparative Example 7 of the present invention. Detailed Implementation

[0056] To address the challenge of enhancing functionality in current filler surface modification methods, this invention aims to provide a functionalized surface modifier, a method for functionalized surface modification, and the modified material thereof. The modification method is characterized by a strong mechanically induced mechanochemical reaction that generates a strong interaction between the initial filler and liquid metal, thereby achieving liquid metal-modified filler. This method requires no solvent, no post-treatment, and no large amount of liquid metal. The resulting modified filler exhibits a macroscopic shape consistent with the initial filler (e.g., powder, fibrous, etc.) and a microscopic feature of a small amount of liquid metal anchoring on the filler surface. The modified filler obtained through the surface modification described in this invention enhances the functionality of the initial filler through the presence of liquid metal and reduces association between initial filler particles through the adhesion of the flowing liquid metal, thus improving the filler's hydrophilicity and oleophilicity, and enhancing its dispersibility.

[0057] In the modification method of the filler of this invention, during modification, the fluidity of the liquid metal firstly allows it to easily and tightly wet the surface of the initial filler without gaps. Secondly, the strong shear force and strong pressure-induced chemical action induced by solid-phase mechanical mixing cause a strong interfacial interaction between the liquid metal and the initial filler, achieving the fixation of the liquid metal, thereby obtaining the liquid metal modified filler. For ceramic fillers, this interaction originates from the strong coordination between the empty orbitals of the liquid metal (such as Ga atoms in gallium indium tin liquid metal, which are rich in empty orbitals) and the lone pairs of electrons on the surface of the ceramic filler (such as the electron-rich O atoms in alumina, the electron-rich N atoms in boron nitride, and the O atoms in barium titanate). For some carbon-based fillers, this interaction may also exist, possibly due to the interaction between the empty orbitals of the liquid metal and the lone pairs of electrons in the oxide layer on the surface of the carbon-based filler (such as the O atoms in graphene oxide and carbon nanotubes). For some metal fillers, this interaction arises from the mechanical activation of the metal filler surface when mixed with metal, the reactivity of the liquid metal and the metal filler leading to the diffusion of interfacial elements and interfacial alloying (in fact, active metals such as aluminum can directly react with liquid metal to form alloys), and the interaction between the empty orbitals of the liquid metal and the lone pairs of electrons of the O atoms in the trace oxide layer on the surface of the metal filler.

[0058] In the preparation of liquid metal modified fillers, controllable factors include the equipment for mechanical mixing, the modification time, the magnitude of mechanical force, the modification atmosphere, and the modification temperature.

[0059] This invention also provides a modified material, which is prepared by the above-described method. The surface-functionalized modified material of this invention is obtained by modifying an initial material (such as a filler) with liquid metal, with a small amount of liquid metal fixed on the material surface. On the one hand, liquid metal, due to its inherent excellent functional properties, can endow the modified material with stronger functionality. On the other hand, liquid metal can also reduce the association between materials (e.g., covalent bonds, hydrogen bonds, hydrophobic interactions, dipole interactions, and conjugation interactions), affecting the surface energy and wettability of the modified material. The oxide layer of the liquid metal can also interact with the polar matrix material. These combined effects make liquid metal-modified fillers promising for improving the dispersion of fillers in different matrix materials (polymers, ceramics, and metals, etc.).

[0060] The resulting modified material (liquid metal anchored filler) can have morphologies of full encapsulation (core-shell structure), partial encapsulation (protruding structure), overlap (bridging structure), and double-yolk structure (liquid metal simultaneously encapsulates multiple filler particles). For example, by controlling the ambient temperature, force magnitude / time / frequency during forced mixing under strong shear, the mechanochemical action can be controlled, thereby controlling the degree of anchoring between the liquid metal and the filler, achieving a transition from partial to full encapsulation of the filler surface. By selecting filler particles with diverse particle sizes for liquid metal surface modification, the liquid metal can bridge small-sized fillers to the surface of large-sized fillers. By selecting nanoscale (1nm-10nm) filler particles with extremely small particle sizes for liquid metal surface modification, the liquid metal can coat multiple small filler particles to form a double-yolk encapsulation structure modification. This may be due to the high surface energy of the liquid metal, which makes it tend to coat rather than spread on the surface of extremely small-sized nanoparticles to form a coating.

[0061] The technical solutions described below, in conjunction with specific implementation schemes, are further explained. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0062] Example 1: Preparation of Gallium Indium Tin Liquid Metal Modified Alumina Filler:

[0063] Four types of modified fillers with different liquid metal contents were prepared by adding 4.0 vol% and 8.0 vol% gallium indium tin liquid metal (purchased from Hunan Zhongcai Shengte New Materials) and 96.0 vol% and 92.0 vol% alumina (purchased from Baitu Technology, particle size 1 μm) to an automatic ball mill. The atmosphere was air, the temperature was 25℃, the rotation speed was 300 rpm, and the milling time was 10 min. Liquid metal modified alumina fillers (LM-Al2O3) with different liquid metal contents were obtained.

[0064] Example 2: Preparation of Gallium Indium Tin Liquid Metal Modified Barium Titanate Filler:

[0065] Four modified fillers with different liquid metal contents were prepared by adding 0.5 vol%, 1.0 vol%, 3.0 vol%, and 6.0 vol% of gallium indium tin liquid metal (purchased from Hunan Zhongcai Shengte New Materials) and 99.5 vol%, 99.0 vol%, 97.0 vol%, and 94.0 vol% of barium titanate (purchased from Shanghai Aladdin, particle size 1 μm) to an automatic grinding mill. The atmosphere was air, the temperature was 25℃, the speed was 100 rpm, and the grinding time was 10 min to obtain liquid metal modified barium titanate fillers with different liquid metal contents (named 0.5LM-BaTiO3, 1LM-BaTiO3, 3LM-BaTiO3, and 6LM-BaTiO3).

[0066] Example 3: Preparation of GaInTin liquid metal modified boron nitride filler:

[0067] 3 vol% of gallium indium tin liquid metal (purchased from Hunan Zhongcai Shengte New Materials) and 97 vol% of boron nitride (purchased from Qinhuangdao Yinuo, particle size 10-15 μm) were added to an automatic grinding machine. The atmosphere was air, the temperature was 25℃, the rotation speed was 200 rpm, and the grinding was carried out for 10 min to obtain liquid metal modified boron nitride filler (LM-BN).

[0068] Example 4: Preparation of gallium indium tin liquid metal modified silicon dioxide:

[0069] Add 5 vol% gallium indium tin liquid metal (purchased from Hunan Zhongcai Shengte New Materials) and 95 vol% silica (purchased from Evonik, particle size <50 nm) to a high-speed mixer. The atmosphere is air, the temperature is 25℃, the speed is 1500 rpm, and the mixture is mixed for 6 minutes to obtain liquid metal modified silica filler.

[0070] Example 5: Preparation of liquid metal-modified boron nitride nanosheet polymer composite material:

[0071] Step 1: 15 vol% of gallium indium tin liquid metal (purchased from Hunan Zhongcai Shengte New Materials) and 85 vol% of boron nitride nanosheets (purchased from Sigma-Aldrich, particle size 200 nm) were added to an automatic ball mill. The atmosphere was nitrogen, the temperature was 25℃, and the rotation speed was 300 rpm for 1 min. The product was then placed in a plowshare mixer and ground for 1 min at 25℃ in an air atmosphere at 100 rpm to obtain liquid metal-modified boron nitride nanosheets.

[0072] Step 2: Liquid metal-modified boron nitride nanosheets were blended with melts of polypropylene (PP), polymethyl methacrylate (PMMA), and polyvinylidene fluoride (PVDF) to prepare three polymer composites (PP / LM-BN, PMMA / LM-BN, and PVDF / LM-BN). The volume ratio of modified filler to polymer matrix was 4:96. The mixing equipment was a micro-mixing rheometer, and the mixing temperatures were 195℃, 225℃, and 200℃, respectively. The mixing speed was 120 rpm, and the mixing time was 10 min. The extruded product was cooled and pelletized to obtain the liquid metal-modified boron nitride nanosheet polymer composite.

[0073] Example 6: Preparation of liquid metal-modified barium titanate polymer composite material:

[0074] Step 1: Add 3 vol% of gallium indium tin liquid metal (purchased from Hunan Zhongcai Shengte New Materials) and 97 vol% of barium titanate (purchased from Shanghai Aladdin, particle size <100nm) to an automatic ball mill. The atmosphere is air, the temperature is 25℃, the rotation speed is 300 rpm, and the grinding time is 5 minutes to obtain liquid metal modified barium titanate filler.

[0075] Step 2: Liquid metal modified barium titanate filler is blended with polyvinylidene fluoride (PVDF) melt to prepare polymer composite material. The volume ratio of modified filler to polymer matrix is ​​5:95. The mixing equipment is a micro-mixing rheometer. The mixing temperature is 195℃, the mixing speed is 120 rpm, and the mixing time is 10 min. The extruded product is cooled and pelletized to obtain liquid metal modified barium titanate polymer composite material.

[0076] Example 7: Preparation of liquid metal modified alumina polymer composite material:

[0077] Step 1: Add 1 vol% of gallium indium tin liquid metal (purchased from Hunan Zhongcai Shengte New Materials) and 99 vol% of alumina (purchased from Baitu Technology, particle size <500nm) to a mortar. Grind in an air atmosphere at 25℃ for 20 minutes at a speed of 120 rpm to obtain liquid metal modified silica filler.

[0078] Step 2: Prepare a polymer composite material by blending liquid metal modified alumina filler with polydimethylsiloxane (PDMS). The volume ratio of modified filler to polymer matrix is ​​50:50. The mixing equipment is a planetary mixer, the mixing temperature is room temperature, the mixing speed is 300 rpm, and the mixing time is 2 min. The product is the liquid metal modified alumina polymer composite material.

[0079] Example 8: Preparation of liquid metal-modified rubidium iron boron polymer composite material:

[0080] Step 1: Add 5 vol% of gallium indium tin liquid metal (purchased from Hunan Zhongcai Shengte New Materials) and 95 vol% of neodymium iron boron (purchased from Galaxy Magnet, particle size ≈10 μm, abbreviated as NdFeB) to an automatic ball mill. The atmosphere is air, the temperature is 25℃, the rotation speed is 300 rpm, and the milling time is 5 min to obtain liquid metal modified neodymium iron boron filler (abbreviated as LM-NdFeB).

[0081] Step 2: Liquid metal-modified rubidium iron boron filler is blended with polyvinylidene fluoride (PVDF) melt to prepare polymer composite material. The volume ratio of modified filler to polymer matrix is ​​10:90. The mixing equipment is a micro-mixing rheometer. The mixing temperature is 195℃, the mixing speed is 120 rpm, and the mixing time is 10 min. The extruded product is cooled and pelletized to obtain liquid metal-modified rubidium iron boron polymer composite material.

[0082] Example 9: Preparation of liquid metal modified silica polymer composite material:

[0083] Step 1: Add 5 vol% of gallium indium tin liquid metal (purchased from Hunan Zhongcai Shengte New Materials) and 95 vol% of silicon dioxide (purchased from Evonik, particle size <50nm) to a high-speed mixer. The atmosphere is air, the temperature is 25℃, the speed is 1500 rpm, and the mixture is mixed for 6 minutes to obtain liquid metal modified silicon dioxide filler.

[0084] Step 2: Liquid metal modified silica filler is blended with polypropylene (PP) melt to prepare polymer composite material. The volume ratio of modified filler to polymer matrix is ​​40:60. The mixing equipment is a micro-mixing rheometer. The mixing temperature is 195℃, the mixing speed is 120rpm, and the mixing time is 10min. The extruded product is cooled and pelletized to obtain liquid metal modified silica polymer composite material.

[0085] Comparative Example 1: Alumina filler (purchased from Bestu Technology, particle size 1μm), without any modification.

[0086] Comparative Example 2: Barium titanate filler (purchased from Shanghai Aladdin, particle size 1μm), without any modification.

[0087] Comparative Example 3: Preparation of silane-modified barium titanate filler:

[0088] The temperature was controlled at 60℃. 2g of γ-methacryloxypropyltrimethoxysilane (silane coupling agent KH570, purchased from Shanghai Aladdin) was mixed with 4g of deionized water and 2g of anhydrous ethanol under magnetic stirring at 200rpm for 1.0h. The solution was then sprayed onto the surface of 200g of uniformly dispersed barium titanate filler powder and dried in a vacuum oven at 60℃ for 8 hours to obtain the silane-modified barium titanate filler (named Silane-BaTiO3).

[0089] Comparative Example 4: Preparation of dopamine-modified barium titanate filler:

[0090] 0.3 g of dopamine hydrochloride (purchased from Macklin) and 30 g of barium titanate filler were added to Tris-HCl buffer solution and mixed for 24 hours at room temperature with magnetic stirring at 200 rpm. The suspension was then centrifuged at 10,000 rpm for 5 minutes, and the precipitate was collected. The mixture was stirred with deionized water, and the centrifugation process was repeated twice to remove unreacted dopamine. Finally, the mixture was dried in a vacuum oven at 60°C for 8 hours to obtain dopamine-modified barium titanate filler (named PDA-BaTiO3).

[0091] Comparative Example 5: Preparation of Boron Nitride Nanosheet Polymer Composite Material

[0092] Three polymer composite materials (PP / BN, PMMA / BN, and PVDF / BN) were prepared by blending boron nitride nanosheets (purchased from Sigma-Aldrich, particle size 200 nm) with melts of polypropylene (PP), polymethyl methacrylate (PMMA), and polyvinylidene fluoride (PVDF). The volume ratio of filler to polymer matrix was 4:96. The mixing equipment was a micro-mixing rheometer, and the mixing temperatures were 195℃, 225℃, and 200℃, respectively. The mixing speed was 120 rpm, and the mixing time was 10 min. The extruded product was cooled and pelletized to obtain the boron nitride nanosheet polymer composite material.

[0093] Comparative Example 6: Preparation of Barium Titanate Polymer Composite Material:

[0094] Barium titanate (purchased from Shanghai Aladdin, particle size <100nm) was blended with polyvinylidene fluoride (PVDF) melt to prepare a polymer composite material. The volume ratio of filler to polymer matrix was 5:95. The mixing equipment was a micro-mixing rheometer. The mixing temperature was 195℃, the mixing speed was 120rpm, and the mixing time was 10min. The extruded product was cooled and pelletized to obtain the barium titanate polymer composite material.

[0095] Comparative Example 7: Preparation of alumina polymer composite material:

[0096] Polymer composites were prepared by blending alumina filler (purchased from Bestu Technology, particle size <500nm) with polydimethylsiloxane (PDMS). The volume ratio of filler to polymer matrix was 50:50. The mixing equipment was a planetary mixer, the mixing temperature was room temperature, the mixing speed was 300 rpm, and the mixing time was 2 min. The product was the alumina polymer composite.

[0097] Preparation of 8 Rubidium Iron Boron Polymer Composites (Comparative Example):

[0098] Rubidium iron boron (purchased from Galaxy Magnet, particle size ≈10μmB) was blended with polyvinylidene fluoride (PVDF) melt to prepare a polymer composite material. The volume ratio of filler to polymer matrix was 10:90. The mixing equipment was a micro-mixing rheometer. The mixing temperature was 195℃, the mixing speed was 120rpm, and the mixing time was 10min. The extruded product was cooled and pelletized to obtain the Rubidium iron boron polymer composite material.

[0099] Comparative Example 9: Preparation of silica polymer composite material:

[0100] Polymer composites were prepared by blending silica (purchased from Evonik, particle size <50nm) with polyvinylidene fluoride (PVDF) melt. The volume ratio of filler to polymer matrix was 40:60. The mixing equipment was a micro-mixing rheometer. The mixing temperature was 195℃, the mixing speed was 120rpm, and the mixing time was 10min. The extruded product was cooled and pelletized to obtain the silica polymer composite.

[0101] Structural and performance characterization

[0102] This invention characterizes the microstructure of liquid metal-modified fillers. The morphologies of liquid metal-modified alumina and liquid metal-modified boron nitride in Examples 1 and 3 (testing equipment: FESEM, Hitachi, S-4800) are as follows: Figure 1 As shown, the comparison with the initial filler and the elemental distribution of gallium verify that liquid gallium indium tin can coat the filler surface with a protruding morphology under strong shear.

[0103] This invention tested the improvement of the intrinsic function of fillers by liquid metal modification. The following explanation uses dielectric constant (tested on a Novo control concept 60) and electromagnetic shielding efficiency (tested on an Agilent N5244Avector) as examples. Figure 2 As shown in Figure a, the comparison between Example 2 and Comparative Example 2 illustrates that the dielectric constant of the liquid metal-modified barium titanate filler increases with the increase of gallium indium tin liquid metal content. At 6 vol%, the dielectric constant increases to 510, which is nearly 1.6 times that of the unmodified initial filler (unmodified barium titanate dielectric constant 320). Figure 2As shown in b, the comparison between Example 1 and Comparative Example 1 illustrates that the electromagnetic shielding performance of liquid metal modified alumina filler increases significantly with the increase of gallium indium tin liquid metal content. At 8 vol%, the electromagnetic shielding reflection efficiency of liquid metal modified alumina increases to 4.1 dB, which is nearly 2.8 times (1.5 dB) that of the unmodified initial filler.

[0104] This invention tested the improvement of filler dispersibility by liquid metal modified fillers, through characterization of the filler's hydrophilicity and oleophilicity (optical contact angle meter, KRUSS DSA25) and assessment of the cross-sectional morphology of the modified filler in the composite material (FESEM, Hitachi, S-4800). Taking modified barium titanate filler as an example, such as... Figure 3 As shown, the comparison between Example 2 and Comparative Examples 2, 3, and 4 illustrates that the wettability of liquid metal modified barium titanate filler to oil and water increases with the increase of gallium indium tin liquid metal content, demonstrating an improvement in amphiphilicity, while silane modified barium titanate and dopamine modified barium titanate only increase oleophilicity / hydrophobicity.

[0105] Figure 4 a calculated Figure 3 The contact angle changes in the liquid metal. At 6 vol% liquid metal, the oil contact angle of the liquid metal modified barium titanate filler decreases to about 55° and the water contact angle decreases to 14°, which indicates that the modified filler has excellent hydrophilicity and good oleophilicity. Figure 4 b indicates that even at the same 1 vol% modification content, liquid metal modification exhibits more pronounced amphiphilicity than dopamine and silane modification, suggesting that liquid metal modified fillers hold promise for improving dispersibility in the matrix materials of various composite materials. Figure 5 As shown, the oil contact angle and water contact angle of the liquid metal modified boron nitride packing (Example 5) are also reduced compared to the original boron nitride packing, indicating that the improvement of the amphiphilicity of the packing by the liquid metal modified packing is valid for different types of packings.

[0106] like Figure 6 As shown, the comparison between Example 5 and Comparative Example 5 illustrates that the initial boron nitride nanosheet filler is extremely prone to agglomeration in polypropylene (PP), polymethyl methacrylate (PMMA), and polyvinylidene fluoride (PVDF). Liquid metal modification can effectively improve the dispersion of boron nitride nanosheet filler, indicating that the effect of liquid metal modification on improving filler dispersion is valid in different types of matrices.

[0107] In addition, such as Figures 7-9As shown, the comparison between Examples 6-8 and Comparative Examples 6-8 illustrates that the dispersion of liquid metal modified barium titanate (LM-BaTiO3), liquid metal modified alumina (LM-Al2O3), and liquid metal modified rubidium iron boron (LM-NdFeB) in the matrix is ​​also improved compared to unmodified barium titanate (BaTiO3), alumina (Al2O3), and rubidium iron boron (NdFeB). This indicates that the dispersion improvement effect of liquid metal modified fillers is valid for different types of fillers.

[0108] Furthermore, this invention also investigated the macroscopic rheological properties of the composite material. Using Example 7 and Comparative Example 7 as examples, this invention used a ramp flow distance test to evaluate the changes in the macroscopic extrusion flowability of the alumina polymer composite material before and after liquid metal modification. Figure 10 As shown, during the 30s test period, the flow distance of the liquid metal modified composite material (PDMS / LM-Al2O3) increased by about 30% compared with that before modification (PDMS / Al2O3), indicating that the modified filler of the present invention improves the flowability and workability of the composite material.

[0109] The present invention also verifies that the functionality of composite materials can be enhanced by liquid metal modified fillers. For example, comparing Example 9 with Comparative Example 9, the electromagnetic shielding efficiency of the liquid metal modified silica polymer composite material can be increased from 0.5 dB in the unmodified silica polymer composite material in the comparative example to 6.1 dB after modification, an increase of 1120%.

Claims

1. A method for improving the dielectric constant and / or hydrophilicity and oleophilicity of fillers, characterized in that, The method involves modifying the filler with a liquid metal-containing substance, and preparing the modified filler by mechanically mixing the filler and the liquid metal-containing substance; wherein the volume ratio of the liquid metal-containing substance to the filler is 0.5 vol%–6.00 vol% : 99.50 vol%–94.00 vol%; the mechanical mixing method utilizes the physicochemical effects induced by shear force and pressure during mixing to modify the filler with liquid metal. The filler is selected from barium titanate, and the liquid metal-containing substance is gallium indium tin liquid metal, with the sum of the volume ratios of gallium indium tin liquid metal and filler being 100%.

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