Modulus-adjustable composite material and preparation method thereof

Abstract

The invention provides a modulus-adjustable composite material and a preparation method thereof. The modulus-adjustable composite material comprises a functional material layer and a magnetofluid layer which are stacked, wherein the magnetic fluid layer comprises liquid metal and a magnetic sensitive material uniformly distributed in the liquid metal; the magnetic sensitive material is controlled through an external magnetic field so as to control phase change of the liquid metal, and modulus adjustment of the magnetic fluid layer is achieved. The modulus of the material can be regulated and controlled in a non-contact mode, flexibility and rigidity are flexibly switched, and the material adapts to complex and changeable environments and diversified requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid metals, and more specifically, to a modulus-adjustable composite material and a preparation method thereof. Background Art

[0002] Liquid metals are a class of metal materials that are liquid at room temperature or near room temperature, such as gallium and its alloys. Due to their unique fluidity, high electrical and thermal conductivity, and reversible liquid-solid phase change characteristics, they have shown great potential in the fields of flexible electronics, soft robotics, biomedicine, etc. at present. Currently, the modulus of liquid metals can be regulated through the phase change process. For example, it exhibits a low modulus in the liquid state, while the modulus can be increased by several times to dozens of times in the solid state. This property makes it an ideal candidate for designing dynamically adjustable materials. However, in the prior art, the phase change regulation of liquid metals mainly relies on temperature changes or contact external force control, which has problems such as slow response speed, high energy consumption, and the need for direct contact, restricting its application in complex environments or non-contact scenarios.

[0003] In addition, the modulus of materials is usually single, and it is difficult to meet the requirements for the rigid-flexible switching and multi-modal mechanical properties of materials in multiple scenarios. For example, traditional flexible pressure sensors usually have a single modulus based on functional composite materials with a fixed structure. However, their detection range (measurement range) is often pre-fixed by the material modulus and structural design. Due to the significant differences in the requirements for the pressure detection range in different scenarios, achieving multi-modal of a single sensor has become one of the focuses of current attention.

[0004] Therefore, how to regulate the modulus of materials in a non-contact manner and achieve multi-modal switching of the overall mechanical properties of composite materials is a technical difficulty that needs to be solved urgently at present. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a modulus-adjustable composite material and a preparation method thereof to solve the problems of high energy consumption, low efficiency, the need for direct contact regulation, and fixed detection range existing in the existing material modulus regulation methods.

[0006] The modulus-adjustable composite material provided by the present invention includes a functional material layer and a ferrofluid layer arranged in a stacked manner; wherein,

[0007] the ferrofluid layer includes liquid metal and magnetic sensitive materials uniformly distributed inside the liquid metal;

[0008] By controlling the magnetic sensitive materials with an external magnetic field, the phase change of the liquid metal is controlled to achieve the modulus adjustment of the ferrofluid layer.

[0009] In addition, an alternative technical solution is that the laminated structure of the magnetorheological fluid layer and the functional material layer includes: a flat multi-layer structure, a core-shell structure, and a network structure; wherein,

[0010] The magnetorheological fluid layer and the functional material layer are alternately distributed.

[0011] In addition, an alternative technical solution is that at least one layer is provided for the functional material layer and the magnetorheological fluid layer respectively; and, the distribution density of the magnetic sensitive material in different magnetorheological fluid layers is different.

[0012] In addition, an alternative technical solution is that the liquid metal includes mercury, gallium, gallium-indium alloy, gallium-indium-tin alloy, and gallium, gallium-indium alloy, gallium-indium-tin alloy doped with at least one transition metal and solid non-metal element.

[0013] In addition, an alternative technical solution is that the magnetic sensitive material includes at least one of metallic iron, nickel, cobalt, manganese, iron tetroxide, metal alloy, ferrite, neodymium iron boron.

[0014] In addition, an alternative technical solution is that, within the magnetorheological fluid layer, the weight percentage range of the magnetic sensitive material to the liquid metal is 5% to 35%.

[0015] In addition, an alternative technical solution is that the material of the functional material layer includes an elastic matrix and a multiphase composite material formed by physical blending or chemical bonding of the elastic matrix with at least one of silver nanowires, liquid metal, carbon nanotubes, graphene, carbon black, PEDOT:PSS; wherein,

[0016] The elastic matrix includes at least one of aliphatic random copolyesters, aromatic random copolyesters, polydimethylsiloxane, rubber-like polymers, resin materials, hydrogels, polyurethanes, polyethylene octene copolymers, and thermoplastic elastomers.

[0017] In addition, an alternative technical solution is that the functional material layer includes a multiphase composite material formed by polydimethylsiloxane and carbon nanotubes; and, the weight ratio range of the carbon nanotubes to the polydimethylsiloxane is 1% to 5%.

[0018] In addition, an alternative technical solution is that the method of incorporating the magnetic sensitive material into the liquid metal includes at least one of mechanical mixing, chemical reduction, surface modification, and electrochemical deposition.

[0019] On the other hand, the present invention also provides a preparation method of a modulus adjustable composite material for preparing the above-mentioned modulus adjustable composite material, the method comprising:

[0020] Mix a magnetic-sensitive material into a liquid metal for uniform mixing to obtain a magnetic fluid; meanwhile, prepare an uncured functional material prepolymer;

[0021] Stack the functional material prepolymer and the magnetic fluid in a preset mold;

[0022] Cure the functional material prepolymer and the magnetic fluid in the preset mold to form the modulus-adjustable composite material.

[0023] Using the above-mentioned modulus-adjustable composite material and preparation method, a composite material is formed by stacking a functional material layer and a magnetic fluid layer. The magnetic fluid layer further includes a liquid metal and a magnetic-sensitive material uniformly distributed inside the liquid metal. During application, by controlling the distribution position of the magnetic-sensitive material through an external magnetic field, the phase change of the liquid metal can be controlled, and then the modulus of the composite material can be adjusted. Non-contact control of the material phase change can be achieved to achieve the effect of regulating the material modulus, and it can meet the multi-environment and diverse requirements for materials, especially in the fields of intelligent robots and medical materials.

[0024] To achieve the above and related purposes, one or more aspects of the present invention include the features described in detail later. The following description and the accompanying drawings detail certain exemplary aspects of the present invention. However, these aspects only indicate some of the various ways in which the principles of the present invention can be used. In addition, the present invention aims to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] By referring to the following description in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more apparent and easier to understand. In the drawings:

[0026] Figure 1 FIG. is a schematic structural diagram of a modulus-adjustable composite material according to an embodiment of the present invention;

[0027] Figure 2 FIG. is a schematic structural diagram of a magnetic fluid layer according to an embodiment of the present invention;

[0028] Figure 3 FIG. is a schematic structural diagram of a modulus-adjustable composite material according to another embodiment of the present invention;

[0029] Figure 4 FIG. is a curve graph showing the relationship between an externally applied magnetic field and the change in the content of the magnetic-sensitive material according to an embodiment of the present invention;

[0030] Figure 5 FIG. is a curve graph showing the relationship between the stress and strain changes of a modulus-adjustable composite material according to an embodiment of the present invention.

[0031] The reference numerals in the above drawings include: functional material layer 1, magnetorheological fluid layer 2, liquid metal 21, magnetic sensitive material 22, functional material layer 1', magnetorheological fluid layer 2'.

[0032] In all the drawings, the same reference numerals indicate similar or corresponding features or functions. Detailed implementation manners

[0033] In the following description, for the purpose of explanation, in order to provide a comprehensive understanding of one or more embodiments, many specific details are set forth. However, it is obvious that these embodiments can also be implemented without these specific details. In other instances, well-known structures and devices are shown in block diagram form for the purpose of facilitating the description of one or more embodiments.

[0034] Those skilled in the art of the present technology can understand that, unless specifically stated otherwise, the singular forms "a", "an", "the" and "said" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present invention means the presence of the described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their groups. It should be understood that the phrase "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0035] Those skilled in the art of the present technology can understand that, unless otherwise defined, all terms (including material terms and scientific terms) used herein have the same meaning as the general understanding of those of ordinary skill in the art to which the present invention belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless defined as such herein.

[0036] To describe in detail the modulus adjustable composite material and preparation method within the present invention, the following will describe in detail the specific embodiments of the present invention with reference to the drawings.

[0037] Figure 1 and Figure 3 respectively show the schematic cross-sectional structures of modulus adjustable composite materials according to two different embodiments of the present invention, Figure 2 shows the schematic structure of the magnetorheological fluid layer according to an embodiment of the present invention.

[0038] Such as Figures 1 to 3As shown together, the modulus-adjustable composite material (hereinafter referred to as the composite material for short) of the embodiment of the present invention includes a functional material layer 1 and a magnetorheological fluid layer 2 arranged in layers; wherein, the magnetorheological fluid layer 2 further includes a liquid metal 21 and a magnetic sensitive material 22 uniformly distributed inside the liquid metal 21. During the application process of the composite material, by controlling the magnetic sensitive material 22 with an external magnetic field, the phase change of the liquid metal 21 can be controlled, thereby realizing the modulus adjustment of the magnetorheological fluid layer 2. Non-contact adjustment can be achieved, and the modulus-adjustable range of the composite material is large, which can meet the application requirements in various scenarios.

[0039] Among them, the laminated structure of the magnetorheological fluid layer 2 and the functional material layer 1 may include: a flat multi-layer structure, a core-shell structure, a network structure, etc. Among them, the flat multi-layer structure is as Figure 1 shown, including the functional material layer 1, the magnetorheological fluid layer 2, the functional material layer 1, the magnetorheological fluid layer 2 arranged flat in sequence, and so on, so that the magnetorheological fluid layer 2 and the functional material layer 1 are distributed alternately; among them, to ensure the overall stability of the composite material, the outermost layer can adopt the functional material layer 1. The core-shell structure is as Figure 5 shown, which is a multi-layer spherical structure, including a functional material layer 1' and a magnetorheological fluid layer 2' arranged in layers, and the outermost layer is the functional material layer 1'. The network structure (not shown in the figure) is a spatial connection structure, and each connection part or connection point can be arranged in the form of a multi-layer structure or a core-shell structure.

[0040] In a specific embodiment of the present invention, at least one layer is provided for the functional material layer 1 and the magnetorheological fluid layer 2 respectively; and, the distribution density of the magnetic sensitive material 22 in different magnetorheological fluid layers 2 can be set to be the same or different; among them, the different distribution densities of the magnetic sensitive material 22 in different magnetorheological fluid layers 2 can be achieved by controlling the magnetic sensitive material 22 during the preparation process of the composite material. After the composite material is prepared, the control of the magnetic sensitive material 22 can be realized by controlling the magnitude of the external magnetic field applied to different magnetorheological fluid layers 2, so that the magnetic sensitive material 22 moves orderly to different degrees in the corresponding magnetorheological fluid layer 2, prompting the liquid metal 21 in the layer to undergo a liquid-solid phase change, and changing the modulus of the liquid metal 21. Therefore, when an external magnetic field acts on the composite material, the modulus of the composite material will also change accordingly.

[0041] Among them, the above-mentioned liquid metal 21 may include mercury, gallium, gallium-indium alloy, gallium-indium-tin alloy, and gallium, gallium-indium alloy, gallium-indium-tin alloy doped with at least one transition metal and solid non-metal element, etc. Preferably, the liquid metal 21 can adopt pure gallium liquid metal 21.

[0042] In addition, the magnetic sensitive material 22 incorporated into the liquid metal 21 may include at least one of metallic iron, nickel, cobalt, manganese, iron tetroxide, metal alloy, ferrite, neodymium iron boron, or other materials capable of orderly movement under the action of a magnetic field. Preferably, the magnetic sensitive material 22 may be iron with good compatibility with the liquid metal 21.

[0043] Specifically, within the magnetofluid layer, the weight percentage range of the magnetic sensitive material 22 to the liquid metal 21 may be set to 5% - 35%.

[0044] In addition, the material of the functional material layer 1 includes an elastic matrix and a multiphase composite material formed by physical blending or chemical bonding of the elastic matrix with at least one material among silver nanowires, liquid metal 21, carbon nanotubes, graphene, carbon black, PEDOT:PSS, etc.; wherein, the elastic matrix further includes at least one of aliphatic random copolyesters, aromatic random copolyesters, polydimethylsiloxane, rubber-like polymers, resin materials, hydrogels, polyurethanes, polyethylene octene copolymers, and thermoplastic elastomers, etc.; preferably, the functional material layer 1 may adopt a multiphase composite material formed by polydimethylsiloxane and carbon nanotubes; and, the weight ratio range of the carbon nanotubes to the polydimethylsiloxane is 1% - 5%.

[0045] During the preparation process of the composite material, the method of incorporating the magnetic sensitive material 22 into the liquid metal 21 includes at least one of mechanical mixing, chemical reduction, surface modification, electrochemical deposition, etc. Preferably, the mechanical mixing method can be adopted to complete it, and specifically, it can be flexibly selected according to the application scenario and performance requirements of the composite material.

[0046] Corresponding to the above modulus-tunable composite material, the present invention also provides a preparation method of a modulus-tunable composite material for preparing the above modulus-tunable composite material, and the method includes:

[0047] S100: Incorporate the magnetic sensitive material into the liquid metal for uniform mixing to obtain a magnetofluid; meanwhile, prepare an uncured functional material prepolymer;

[0048] S200: Stack the functional material prepolymer (forming the functional material layer after curing) and the magnetofluid (forming the magnetofluid layer after curing) in a preset mold;

[0049] S300: Cure the functional material prepolymer and the magnetofluid in the preset mold to form a modulus-tunable composite material, including a magnetofluid layer and a functional material layer.

[0050] Among them, the preset mold can be correspondingly set according to the required size and laminated structure of the composite material. After the functional material prepolymer and the magnetic fluid are laminated and distributed in the preset mold, the composite material can be formed through curing treatment. Among them, the curing temperature can be controlled at 60°C to 100°C, and the curing time is 1 to 4 hours. Preferably, the temperature of 80°C is selected for curing for 2 hours.

[0051] Example 1

[0052] The liquid metal is selected as gallium, the magnetic sensitive material is selected as Fe particles, and the functional material is selected as CNT@PDMS, that is, carbon nanotube@polydimethylsiloxane is a composite material composed of carbon nanotubes (CNT) and polydimethylsiloxane (PDMS).

[0053] The method for preparing the modulus-adjustable composite material using the above materials includes:

[0054] 1. Incorporate Fe particles into the liquid metal gallium by mechanical mixing method to obtain magnetic fluid. The weight percentage of Fe particles to liquid metal gallium is 10%;

[0055] 2. Mix CNT and PDMS evenly to prepare an uncured CNT@PDMS prepolymer;

[0056] 3. Use a preset mold to fix the mixed magnetic fluid layer by layer in the CNT@PDMS prepolymer to obtain a preliminary composite material;

[0057] 4. Cure the preliminary composite material in step 3 at 80°C for 2 hours to form a composite material.

[0058] Example 2

[0059] 1. Incorporate 0.5 g of Fe particles into 4.5 g of liquid metal gallium by mechanical mixing method;

[0060] 2. Uniformly mix 0.5 g of CNT and 10 g of PDMS to prepare an uncured CNT@PDMS composite prepolymer.

[0061] 3. Use a mold to fix the mixed gallium-iron material inside the CNT@PDMS composite prepolymer and cure it at 80°C for 2 hours to form a composite material.

[0062] Figure 4 and Figure 5 respectively show the relationship curve between the applied magnetic field and the change in the content of the magnetic sensitive material according to the embodiments of the present invention, and the relationship curve between the stress and strain changes of the modulus-adjustable composite material. As Figure 4As shown, as the iron content increases, the magnetic field required to trigger the phase change of liquid metal gallium also increases. When using gallium-iron materials as the magnetic fluid layer to form different laminated structures in combination with functional materials, gallium-iron materials (magnetic fluids) with different doping amounts can be used. For example, in a multi-layer structure, gallium-iron materials with different contents are used in different layers. Applying a small magnetic field to the gallium-iron material with a small content can trigger the phase change of the liquid metal, without triggering the phase change of the gallium-iron material with a large content. When applying a large magnetic field, the phase change of the gallium-iron material with a large content can be triggered. Thus, multiple modes of modulus change of the material can be achieved.

[0063] As Figure 5 shown, the ratio of stress to strain (the slope of the curve) represents the modulus of the composite material. The larger the slope, the larger the modulus. It can be seen that the modulus of the initial CNT@PDMS material is as shown by the middle dashed line. After being combined with 10 wt% gallium-iron material, when the gallium-iron material is in a liquid state, as shown by the lower curve, the modulus of the material decreases. When applying a magnetic field of 70 mT, the 10 wt% gallium-iron material undergoes a phase change and turns into a solid state. At this time, the modulus of the material increases, as shown by the upper curve.

[0064] In the application process of the above composite material, first, at room temperature, different magnetic fields can be applied to the magnetic fluid layer, and the critical magnetic field size that causes the phase change of the liquid metal can be measured to obtain a series of reference values of the relationship between the magnetic field size and the content change of the magnetic-sensitive material. Then, according to the magnetic field size in the relationship reference values, the required magnetic field intensity can be applied to the composite material, and then the modulus of the composite material in different liquid-solid phase change states of the liquid metal can be measured until the application requirements are met.

[0065] It should be noted that the above-described preparation method embodiments can refer to the descriptions in the modulus-tunable composite material embodiments. The content in the method and material embodiments can be mutually referenced and will not be elaborated here one by one.

[0066] According to the above modulus-tunable composite material and preparation method of the present invention, a composite material is formed by laminating a functional material layer and a magnetic fluid layer, and the magnetic fluid layer further includes a liquid metal and a magnetic-sensitive material uniformly distributed inside the liquid metal. In the application process, by controlling the distribution position of the magnetic-sensitive material in different layers through an external magnetic field, the phase change of the liquid metal in the corresponding layer can be controlled, and thus the modulus of the composite material can be adjusted. Non-contact control of the material phase change can be achieved to achieve the effect of regulating the material modulus. The modulus regulation range is wide, the material shape is controllable, and it can adapt to multi-environment and diverse application requirements.

[0067] The modulus-adjustable composite material and preparation method according to the present invention are described by way of example with reference to the accompanying drawings above. However, those skilled in the art should understand that various improvements can be made to the above-mentioned modulus-adjustable composite material and preparation method of the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the appended claims.

Claims

1. A composite material with adjustable modulus, characterized in that: It comprises a functional material layer and a magnetic fluid layer which are stacked; wherein, The magnetic fluid layer includes liquid metal and magnetically sensitive material uniformly distributed inside the liquid metal; The magnetically sensitive material is controlled by an external magnetic field to control the phase change of the liquid metal and achieve the modulation of the modulus of the magnetic fluid layer.

2. The modulus adjustable composite material according to claim 1, characterized in that: The stacked structure of the magnetic fluid layer and the functional material layer includes: a flat multilayer structure, a core-shell structure and a network structure; wherein, The magnetic fluid layer and the functional material layer are distributed alternately with each other.

3. The modulus adjustable composite material according to claim 1, characterized in that: The functional material layer and the magnetic fluid layer are respectively provided with at least one layer; and the distribution density of the magnetically sensitive material in different magnetic fluid layers is different.

4. The modulus adjustable composite material according to claim 1, characterized in that: The liquid metal includes mercury, gallium, gallium-indium alloy, gallium-indium-tin alloy, and gallium, gallium-indium alloy, gallium-indium-tin alloy doped with at least one transition metal or solid non-metallic element.

5. The modulus adjustable composite material according to claim 1, characterized in that: The magnetically sensitive material includes at least one of metallic iron, nickel, cobalt, manganese, ferroferric oxide, metal alloy, ferrite, and neodymium iron boron.

6. The modulus adjustable composite material according to claim 1, characterized in that: In the magnetic fluid layer, the weight percentage of the magnetically sensitive material and the liquid metal ranges from 5% to 35%.

7. The modulus adjustable composite material according to claim 1, characterized in that: The material of the functional material layer includes an elastic matrix and a multiphase composite material formed by physically blending or chemically bonding the elastic matrix with at least one of silver nanowires, liquid metals, carbon nanotubes, graphene, carbon black, and PEDOT:PSS; wherein, The elastic matrix includes at least one of aliphatic random copolyester, aromatic random copolyester, polydimethylsiloxane, rubber polymer, resin material, hydrogel, polyurethane, polyethylene octene co-elastomer and thermoplastic elastomer.

8. The composite material with adjustable modulus according to claim 7, characterized in that: The functional material layer comprises a multiphase composite material formed by polydimethylsiloxane and carbon nanotubes; and the weight ratio of the carbon nanotubes to the polydimethylsiloxane is in the range of 1% to 5%.

9. The composite material with adjustable modulus according to claim 1, characterized in that: The manner of adding the magnetic sensitive material into the liquid metal includes at least one of mechanical mixing, chemical reduction, surface modification, and electrochemical deposition.

10. A method for preparing a composite material with adjustable modulus, characterized in that: For preparing the modulus-adjustable composite material according to any one of claims 1 to 9, the method comprises: The magnetically sensitive material is added to the liquid metal for uniform mixing to obtain a magnetic fluid; meanwhile, an uncured functional material prepolymer is prepared; Laying the functional material prepolymer and the magnetic fluid in a preset mold; The functional material prepolymer and the magnetic fluid in the preset mold are cured to form the modulus-adjustable composite material.

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