Multi-modal liquid metal droplet fiber and method of making same

Abstract

The application provides a multi-morphology liquid metal droplet fiber and a preparation method thereof. The multi-morphology liquid metal droplet fiber is prepared by using microfluidic spinning technology, and comprises a fiber substrate and metal droplets which are distributed on the fiber substrate at intervals. The metal droplets have multiple morphologies, and the fiber has more flexible and controllable surface topography, and can be applied to the regulation of the fluid interface on the fiber.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fiber materials, in particular to a multi-morphology liquid metal droplet fiber and a preparation method thereof. BACKGROUND

[0002] Droplet microfluidic spinning technology is an effective method for generating droplet sequences or jets in immiscible fluids. By solidifying the continuous phase in the generated two-phase system, spindle-shaped fibers or core-shell fibers can be produced. This method of producing fibers is called microfluidic spinning technology. For spindle-shaped fibers, their periodic surface morphology is similar to that of spider silk, which can promote the attachment and growth of droplets in water mist, thereby achieving efficient water mist collection. For core-shell structures, by using a conductive liquid as the core, it is easy to prepare stretchable fibers with conductivity, which can be widely used in the design and preparation of flexible electronic devices.

[0003] Liquid metal generally refers to metals with melting points below room temperature, including mercury, gallium, etc. It has excellent fluidity, electrical conductivity, thermal conductivity, etc. and is widely used in flexible electronics. Among them, mercury has toxicity and volatility, so devices based on mercury often face reliability and safety problems. Gallium-based liquid metal is non-toxic and non-volatile, which is an excellent choice for liquid metal device design.

[0004] In previous studies, scholars often study how to use gallium-based liquid metal for the preparation of flexible wires, including electrospinning technology, microfluidic spinning technology, etc. However, the research on liquid metal in the preparation of core-shell fibers has been overlooked. In addition, the microfluidic spinning method in the current literature report can only form spherical dispersed phase droplets, because of the influence of the surface tension of the two-phase interface, the droplets tend to form spherical droplets to reduce the phase interface area, but the limitation of surface tension also limits the shape of the droplet, thereby limiting the further expansion of the surface morphology of the fiber. SUMMARY

[0005] In order to overcome the deficiencies in the prior art, the main purpose of the present application is to provide a multi-morphology liquid metal droplet fiber and a preparation method thereof. The multi-morphology liquid metal droplet fiber is prepared by microfluidic spinning technology, which includes a fiber matrix and metal droplets spaced apart on the fiber matrix; and the metal droplets have multiple morphologies, which give the fiber a more flexible and controllable surface morphology, and can be applied to the regulation of the fluid interface on the fiber.

[0006] In order to achieve the above purpose, according to the first aspect of the present application, a multi-morphology liquid metal droplet fiber is provided.

[0007] The multi-form liquid metal droplet fiber is prepared by using micro-fluid spinning technology, and comprises a fiber substrate and metal droplets which are distributed in the fiber substrate at intervals.

[0008] Further, the metal droplets are in spherical, ellipsoidal or conical shape.

[0009] Further, the metal droplets are located inside the fiber substrate, and the surface of the metal droplets is wrapped with an oxide film.

[0010] Further, the metal droplets are at least partially exposed outside the fiber substrate, and the surface of the metal droplets is wrapped with an oxide film.

[0011] Further, the metal droplets include, but are not limited to, pure gallium, gallium-indium alloy, gallium-indium-tin alloy, gallium-indium-tin-zinc alloy droplets.

[0012] Preferably, the material of the fiber substrate includes, but is not limited to, hydrogel.

[0013] In order to achieve the above-mentioned purpose, according to the second aspect of the present application, a preparation method of a multi-form liquid metal droplet fiber is provided.

[0014] The preparation method of the multi-form liquid metal droplet fiber is based on micro-fluid spinning technology, and comprises the following steps:

[0015] Liquid metal and a curable solution with a certain amount of dissolved oxygen are used, and the injection speed of the two is controlled to obtain a curable solution with metal droplets distributed at intervals inside; wherein the form of the metal droplets can be controlled.

[0016] The curable solution with metal droplets distributed at intervals is subjected to a curing treatment to obtain the multi-form liquid metal droplet fiber.

[0017] Further, the content of the dissolved oxygen in the curable solution is ≥1mg / L.

[0018] Further, the curable solution includes, but is not limited to, sodium alginate solution, polyethylene glycol diacrylate, PDMS prepolymer.

[0019] Preferably, the curing solution used in the curing treatment includes, but is not limited to, calcium chloride solution.

[0020] Further, the curing treatment includes, but is not limited to, temperature curing, light curing and ion-induced curing.

[0021] Further, the preparation method further comprises post-treatment of the liquid metal droplet fiber; wherein the post-treatment includes, but is not limited to, standing and drying, centrifugation and surface modification.

[0022] The present application is based on microfluidic spinning technology, and utilizes the mechanical support characteristics of the oxide film in the metal droplet generation process to obtain metal droplets with different morphologies, thereby preparing liquid metal droplet fibers with various morphologies.

[0023] Moreover, due to the high density characteristics of gallium-based liquid metal, the fiber can also be post-processed to form more morphological liquid metal droplet fibers, and the fiber can be endowed with more flexible and controllable surface topography, which can be applied to the regulation of the fluid interface on the fiber.

[0024] In addition, the metal droplets in the present application can be selectively exposed outside the fiber substrate (solidified phase), thereby generating asymmetric fibers with different morphologies. In addition, the exposed metal droplet phase has different fluid wettability from the solidified phase, and the directional transport on the liquid metal droplet fiber can be regulated through further surface modification, thereby realizing efficient water mist collection and transmission. BRIEF DESCRIPTION OF DRAWINGS

[0025] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not intended to limit the scope of the present application. Moreover, like reference numerals designate like parts throughout the several views in the drawings. In the drawings:

[0026] Figure 1 Structure diagram of the preparation device in the embodiments provided by the present application;

[0027] Figure 2 Several basic morphologies / configurations of the metal droplets in the embodiments provided by the present application;

[0028] Figure 3 Liquid metal droplet fibers before dehydration formed in the embodiments provided by the present application;

[0029] Figure 4 Several basic configurations of the liquid metal droplet fibers in the embodiments provided by the present application.

[0030] In the drawings:

[0031] 1, first injection device; 1-1, solidifiable solution; 2, second injection device; 2-1, liquid metal; 3, droplet generation device; 3-1, first channel; 3-2, second channel; 4, delivery channel; 5, solidification device; 6, multi-morphology liquid metal droplet fiber; 6-1, fiber substrate; 6-2, metal droplet. DETAILED DESCRIPTION

[0032] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood, and so that the full scope of the present disclosure is conveyed to those skilled in the art.

[0033] In view of the fact that gallium-based liquid metal is easily oxidized in an oxygen-containing environment, and the solid oxide layer can mechanically support the morphology of the liquid, the present application innovatively forms an oxide film wrapped around the surface of the metal droplet at the moment when the gallium-based liquid metal is continuously sheared into metal droplets. And due to the introduction of the solid oxide film, compared with traditional droplet microfluidics, the metal droplet can generate more abundant morphologies in principle.

[0034] In the present application, metal droplets with different configurations / morphologies are prepared by microfluidic spinning technology, and a continuous phase is used to build a multi-morphology liquid metal droplet fiber. Further, through post-processing of the fiber, a liquid metal droplet fiber with more abundant configuration can be obtained, thereby endowing the liquid metal droplet fiber with potential fluid directional transport capability, and being applied to efficient water mist directional collection.

[0035] According to the specific embodiments of the present application, a multi-morphology liquid metal droplet fiber is provided.

[0036] The multi-morphology liquid metal droplet fiber in the present application is prepared by microfluidic spinning technology.

[0037] As shown in Figure 4 , the multi-morphology liquid metal droplet fiber 6 includes a fiber base 6-1 and metal droplets 6-2 spacedly distributed on the fiber base 6-1; wherein the metal droplets 6-2 have multiple morphologies.

[0038] As shown in Figure 2 , the metal droplets 6-2 are spherical, ellipsoidal or conical.

[0039] It is worth mentioning that only spherical, ellipsoidal and conical droplet morphologies are given as examples in the present application, and in actual preparation, the method provided by the present application can be used to control the implementation according to requirements, and is not specifically limited.

[0040] As an embodiment of the present application, the metal droplets 6-2 are located inside the fiber base 6-1, and the surface of the metal droplets 6-2 is wrapped with an oxide film.

[0041] As shown in Figure 4 (i) and (ii), the metal droplets 6-2 are formed inside the fiber base 6-1, and the morphology of the metal droplets 6-2 can be spherical, ellipsoidal or conical.

[0042] Figure 4 The polymorphic liquid metal droplet fiber 6 shown in (i) and (ii) can be regarded as a symmetrical spindle knot fiber, and due to the periodically changing diameter, can be used for efficient water mist collection; and for the spindle knot fiber constructed by the conical metal droplet 6-2, due to the droplet shape imitating the conical needle tip of a cactus, theoretically, efficient water mist collection and directional transport of droplets can be realized.

[0043] As another embodiment in the application, the metal droplet 6-2 is at least partially exposed outside the fiber substrate 6-1, which can be understood as that the metal droplet 6-2 is partially exposed outside the fiber substrate 6-1, and the surface of the metal droplet 6-2 is wrapped with an oxide film, such as Figure 4 shown in (iii); or the metal droplet 6-2 is entirely exposed outside the fiber substrate 6-1, and the surface of the metal droplet 6-2 is wrapped with an oxide film, such as Figure 4 shown in (iv).

[0044] Figure 4 The polymorphic liquid metal droplet fiber 6 shown in (iii) and (iv) can be regarded as an asymmetric spindle knot fiber. For the asymmetric spindle knot fiber, two types of surfaces are introduced: the liquid metal oxide film surface and the fiber substrate surface (such as the hydrogel surface), and by regulating the wettability of the two interfaces, directional transport of liquid on the fiber can also be realized.

[0045] In addition, the asymmetric spindle knot fiber has a morphology close to a caterpillar (see Figure 4 shown in (iv)), and by doping the metal droplet 6-2 or constructing a magnetic droplet, the fiber can be used for construction of a micro-worm robot.

[0046] In the embodiments of the application, the metal droplet 6-2 includes but is not limited to a pure gallium droplet, a gallium-indium alloy droplet, a gallium-indium-tin alloy droplet, and a gallium-indium-tin-zinc alloy droplet.

[0047] In the embodiments of the application, the material of the fiber substrate 6-1 includes but is not limited to a hydrogel.

[0048] According to the specific embodiments of the application, a polymorphic gallium-based liquid metal droplet fiber preparation device is also provided.

[0049] The preparation of the polymorphic liquid metal droplet fiber in the application is based on the preparation device.

[0050] As Figure 1As shown, the preparation device of the multi-state liquid metal droplet fiber comprises a first injection device 1, a second injection device 2, a droplet generation device 3 and a solidification device 4, wherein the first injection device 1 is used for containing a solidifiable solution 1-1; the second injection device 2 is used for containing a liquid metal 2-1; the droplet generation device 3 has a first channel 3-1 and a second channel 3-2, the second channel 3-2 is nested in the first channel 3-1, and the length of the second channel 3-2 is less than that of the first channel 3-1; wherein the first channel 3-1 is communicated with the first injection device 1, and the second channel 3-2 is communicated with the second injection device 2; the solidification device 5 is communicated with the droplet generation device 3 through a conveying channel 4.

[0051] In the embodiment of the present application, the first injection device 1 and the second injection device 2 both realize the controllable injection of the solidifiable solution 1-1 and the liquid metal 2-1 by using the combination of the injection pump and the syringe; wherein the solidifiable solution can adopt sodium alginate solution, and the liquid metal can adopt gallium-indium-tin alloy.

[0052] In the embodiment of the present application, the droplet generation device 3 can realize the generation of the metal droplet 6-2 by the nested injection needle head forming a coaxial flow microfluidic system.

[0053] It is worth mentioning that the droplet generation device 3 in the present application includes but is not limited to the coaxial flow microfluidic system and the flow focusing microfluidic system; wherein the form of the microfluidic system includes but is not limited to the microfluidic chip type and the capillary assembly type, which can be selected according to the actual situation.

[0054] In the embodiment of the present application, the conveying channel 4 adopts a silica gel hose, which is convenient for observation and adjustment.

[0055] It is worth mentioning that the conveying channel 4 can be set to different lengths based on hydrodynamics, so as to induce the metal droplet 6-2 to move to different distances along the axial direction according to the density difference between the metal droplet 6-2 and the solidifiable solution 1-1, and construct different liquid metal droplet fibers 6.

[0056] In the embodiment of the present application, the solidification solution in the solidification device 5 can adopt calcium chloride solution, so as to realize the rapid crosslinking of the sodium alginate solution and construct the gallium-based multi-state liquid metal droplet fiber.

[0057] According to the specific embodiment of the present application, a preparation method of the multi-state liquid metal droplet fiber is also provided.

[0058] The preparation method of the multi-state liquid metal droplet fiber in the present application is based on the microfluidic spinning technology and the above preparation device.

[0059] The preparation method of the multi-state liquid metal droplet fiber in the present application comprises the following steps:

[0060] 1) Adopt liquid metal 2-1 and the solidifiable solution 1-1 with a certain dissolved oxygen, and respectively fill into the second injection device 2 and the first injection device 1.

[0061] 2) Then, the liquid metal 2-1 and the solidifiable solution 1-1 with a certain dissolved oxygen are injected into the droplet generation device 3, and the injection speed of the two is controlled to obtain the solidifiable solution with internal interval distribution of metal liquid droplets 6-2; wherein, the form of the metal liquid droplets 6-2 can be controlled.

[0062] In the embodiment of the present application, under the action of flow shear, the liquid metal 2-1 at the shear necking can be oxidized, and the surface of the generated metal liquid droplet 6-2 can be covered with an oxide film. The mechanical support effect of the oxide film makes the metal liquid droplet 6-2 have rich morphology / configuration, including spherical, non-spherical and the like. Figure 2 The first injection device 1 and the second injection device 2 can generate metal liquid droplets 6-2 with various forms under different injection speeds.

[0063] In the present application, because there is dissolved oxygen in the solidifiable solution 1-1, the surface of the generated metal liquid droplet 6-2 will be covered with an oxide film to fix the droplet form, and by controlling the injection speed, the formation of the metal liquid droplet 6-2 form can be affected: increasing the injection speed will affect the oxidation degree of the liquid metal exposed at the flow shear end, the faster the metal liquid droplet 6-2 is generated, the more difficult it is for the oxide film to form during the droplet shearing process, so the metal liquid droplet 6-2 presents spherical shape; with the decrease of the injection speed, the oxide film gradually forms in the droplet shearing process, so the form of the metal liquid droplet 6-2 gradually approaches ellipsoidal, conical.

[0064] It should be noted that the injection speed in the present application can be adjusted and selected according to actual conditions, the purpose is to form an oxide film on the surface of the metal liquid droplet 6-2 to fix the form of the droplet, and finally obtain the multi-morphology liquid metal liquid droplet fiber 6.

[0065] Moreover, in the present application, the injection speed of the first injection device 1 and the second injection device 2 is continuously adjustable, so that metal liquid droplets 6-2 with different sizes, intervals and forms can be continuously generated.

[0066] In addition, through the design of hydrodynamics, the size, interval and distance along the axis of the metal liquid droplet 6-2 can be continuously adjusted, so as to form a variety of forms and required liquid metal liquid droplet fibers 6.

[0067] In the embodiment of the present application, for gallium-based liquid metal, the content of dissolved oxygen in the solidifiable solution 1-1 is ≥1mg / L, so as to ensure that the gallium-based liquid metal can form an oxide film covering the metal liquid droplet 6-2 when sheared at the droplet generation device 3.

[0068] Of course, the content of dissolved oxygen in the curable solution 1-1 can also be designed and selected according to actual conditions, and is not specifically limited.

[0069] 3) The curable solution 1-1 with the metal droplets 6-2 distributed thereon is then introduced into the curing device 5 through the conveying channel 4, and is subjected to a curing treatment to obtain the multi-form liquid metal droplet fiber 6.

[0070] As an embodiment of the present application, the curable solution includes but is not limited to a sodium alginate solution, a polyethylene glycol diacrylate, and a PDMS prepolymer.

[0071] In the embodiment of the present application, the curable solution in the curing device 5 is a calcium chloride solution, and the Ca 2+ The sodium alginate solution can be quickly cross-linked to form a hydrogel, so that the liquid metal droplet fiber 6-2 is formed as shown in the liquid metal droplet fiber before dehydration. Figure 3

[0072] Subsequently, the liquid metal droplet fiber 6-2 is taken out of the calcium chloride solution and is dried at room temperature. During the drying process, the hydrogel is dehydrated and shrinks, but the volume of the metal droplet 6-2 does not change. Therefore, the metal droplet 6-2 can be selectively wrapped in the hydrogel to form a symmetrically shaped spindle knot fiber, or the metal droplet 6-2 can be exposed outside the hydrogel to form an asymmetrically shaped spindle knot fiber.

[0073] In the embodiment of the present application, the curing solution used in the curing treatment includes but is not limited to a calcium chloride solution.

[0074] In the embodiment of the present application, the curing treatment includes but is not limited to temperature curing, light curing, and ion-induced curing.

[0075] The preparation method in the present application further includes post-treatment of the obtained liquid metal droplet fiber 6; wherein the post-treatment includes but is not limited to standing drying, centrifugation, surface modification, etc.

[0076] As an embodiment of the present application, in order to obtain a liquid metal droplet fiber with more forms, the obtained liquid metal droplet fiber 6 can be subjected to post-treatment operations such as standing drying, centrifugation, and surface modification.

[0077] It should be noted that the terms "comprising" and their any variations as used in the specification and claims of the present application are intended to cover non-exclusive inclusion, for example, a series of components are included without being limited to those components clearly listed, and other components not clearly listed or inherent to the components can be included.

[0078] ​In the present application, the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are mainly used for better description of the present application and its embodiments, and are not used to limit the indicated devices, elements or components must have a particular orientation, or be constructed and operated in a particular orientation.

[0079] In addition, in addition to the above-mentioned terms can be used to indicate the orientation or positional relationship, but also can be used to represent other meanings, for example, the term "upper" in some cases can also be used to represent a certain dependent relationship or connection relationship. For those skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific circumstances.

[0080] In addition, the description of "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features.

[0081] In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appear contradictory or can not be realized, it should be considered that the combination of technical solutions does not exist, also not within the scope of protection required by the present application.

[0082] The above is only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A multi-morphology liquid metal droplet fiber, characterized in that, The multi-morphology liquid metal droplet fiber is prepared by using a microfluidic spinning technology, and includes a fiber substrate and metal droplets which are spacedly distributed on the fiber substrate; wherein the metal droplets have multiple morphologies. The metal droplets are located inside the fiber substrate or at least partially exposed outside the fiber substrate, and the surface of the metal droplets is wrapped with an oxide film.

2. The multi- morphic liquid metal droplet fiber of claim 1, wherein, The metal droplets are in spherical, ellipsoidal or conical shapes.

3. The multi- morphic liquid metal droplet fiber of claim 1, wherein, The metal droplets include pure gallium, gallium-indium alloy, gallium-indium-tin alloy or gallium-indium-tin-zinc alloy droplets.

4. The multi- morphic liquid metal droplet fiber of claim 1, wherein, The material of the fiber substrate is hydrogel.

5. The method for preparing multimorphic liquid metal droplet fibers according to any one of claims 1-4, characterized in that, The preparation method is based on the microfluidic spinning technology, and includes the following steps: Liquid metal and a solidifiable solution with a certain amount of dissolved oxygen are used, and the injection speeds of the two are controlled to obtain the solidifiable solution with the metal droplets spacedly distributed inside; wherein the morphology of the metal droplets is adjustable and controllable. The solidifiable solution with the metal droplets spacedly distributed is subjected to solidification treatment to obtain the multi-morphology liquid metal droplet fiber.

6. The production method according to claim 5, wherein The content of the dissolved oxygen in the solidifiable solution is greater than or equal to 1 mg / L.

7. The production method according to claim 5, wherein The solidifiable solution includes sodium alginate solution, polyethylene glycol diacrylate or PDMS prepolymer.

8. The production method according to claim 5, wherein The solidification solution used in the solidification treatment is calcium chloride solution.

9. The production method according to claim 5, wherein The solidification treatment includes temperature solidification, light solidification or ion-induced solidification.

10. The production method according to claim 5, wherein The preparation method further includes post-treatment of the liquid metal droplet fiber; wherein the post-treatment includes standing and drying, centrifugation or surface modification.

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