Ultra-tensile polymer conductive material, and preparation method therefor and use thereof

Abstract

An ultra-tensile polymer conductive material, and a preparation method therefor and a use thereof. The ultra-tensile polymer conductive material comprises a plurality of one-dimensional nano materials and a plurality of liquid metal fragments; the one-dimensional nano materials are connected by means of the liquid metal fragments to form a conductive network having a linear framework and form a flexible island-bridge structure; in the island-bridge structure, the liquid metal fragments are islands, and the one-dimensional nano materials are bridges; when the ultra-tensile polymer conductive material is stretched under stress, the liquid metal fragments are self-organized and aggregated or broken to maintain the resistance stability of the conductive network. In the present application, the liquid metal fragments are connected by means of rearrangement of the one-dimensional nano materials, enhancing the conductivity of a conductor during stretching. The flexible island-bridge structure mitigates adverse effects of mechanical stress on electronic performance, maintains almost constant resistance and achieves high conductivity. When the ultra-tensile polymer conductive material is applied to an interconnector, the stability of signal transmission can be kept during ultra-tensile deformation.

Description

A super-stretchable polymer conductive material and its preparation method and application Technical Field

[0001] The present application relates to an ultra-stretchable polymer conductive material and a preparation method and application thereof, belonging to the field of new material technology. Background Art

[0002] Stretchable electronics are a promising technology with applications in many emerging devices, such as flexible cardiovascular robots, soft underwater surveillance robots, and biomimetic electronic eyes, where flexibility and electrical conductivity are crucial to achieving their fundamental requirements. The harmonious integration of these devices will require tightly coupled conformal and curvilinear electronic materials that extend and contract over thousands of cycles. Many design strategies for stretchable electronic materials pair conductive microstructures (such as metal foils, metal / carbon filler networks, or meshes) with elastic matrices or substrates. While these approaches reliably maintain good electrical properties under short dielectric strains, they struggle to achieve high elongation and cycling stability. To overcome these limitations, some strategies for fabricating stretchable conductors have turned to intrinsically stretchable materials, such as conducting polymers, ionic liquids, and liquid metals. While conjugated polymers and ionic fluids suffer from low carrier mobility, liquid metals (such as non-toxic gallium alloys) offer the higher conductivity range required for applications such as radiofrequency operation. For example, serpentine-structured liquid metal antennas are often frequency-stabilized, but they cannot avoid wrinkling outside the surface, making mechanical frequency tuning impossible.

[0003] The rigid island-bridge structure emphasizes accommodating traditional bulky non-stretchable functional elements into the non-stretchable island area, while localizing the strain to the peripheral stretchable interconnection, with structural stretchable bending, tortuosity and buckling design, thereby achieving device-level stretchability. In the context of island material selection, the preferred choice is usually local materials (such as brittle semiconductors, rigid metal layers). Elastic bridging elements usually have periodic shapes (such as serpentine, wavy, two-dimensional / three-dimensional buckling configurations). However, the stretchability of this typical structure is limited by the stability of the island to tensile and shear stresses, the stretchability of the bridge and the bridge / island ratio.

[0004] Summary of the Invention

[0005] In view of the above situation, the existing design strategies for achieving a balance between the mechanical and electrical properties of stretchable conductors in the prior art are still subject to obvious limitations. In order to solve the above problems, this application proposes a novel stretchable conductor structure design strategy.

[0006] This application adopts the following technical solutions:

[0007] According to one aspect of the present application, an ultra-stretched polymer conductive material is provided, wherein the ultra-stretched polymer conductive material comprises a plurality of one-dimensional nanomaterials and a plurality of liquid metal fragments;

[0008] The one-dimensional nanomaterials are connected by liquid metal fragments to form a conductive network with a linear skeleton and a flexible island-bridge structure;

[0009] In the island-bridge structure, the liquid metal fragments are islands and the one-dimensional nanowires are bridges;

[0010] When the ultra-stretchable polymer conductive material is stretched under stress, liquid metal fragments self-organize, aggregate, or break to maintain the resistance stability of the conductive network.

[0011] Optionally, the volume conductivity of the ultra-stretchable polymer conductive material is greater than 2.6×10 5 S / cm.

[0012] Optionally, the one-dimensional nanomaterial has a length of 5 to 100 μm.

[0013] Optionally, the weight ratio of the one-dimensional nanomaterial to the liquid metal fragments in the ultra-stretchable polymer conductive material is 1:0.35-25.

[0014] Optionally, the one-dimensional nanomaterial is selected from at least one of gold nanowires, silver nanowires, and carbon nanotubes;

[0015] Optionally, the liquid metal is selected from eutectic gallium and indium.

[0016] Optionally, the ultra-stretchable polymer conductive material further comprises an elastic substrate, and the conductive network is deposited on the surface of the elastic substrate;

[0017] Optionally, the elastic substrate is a hydrogel.

[0018] According to another aspect of the present application, a method for preparing the above-mentioned ultra-stretchable polymer conductive material is provided, comprising the following steps:

[0019] S1, coating the one-dimensional nanomaterial dispersed in the aqueous solution on the surface of the elastic substrate, and vacuum drying to form a one-dimensional conductive layer;

[0020] S2. Spin-coating liquid metal on the one-dimensional conductive layer obtained in step S1 to obtain an ultra-stretchable polymer conductive material through self-assembly.

[0021] Optionally, the content of the one-dimensional nanomaterial in the raw material solution is:

[0022] Optionally, the mass concentration of the liquid metal on the ultra-stretched polymer conductive material after spin coating is 1.5-25 wt %, which is relative to the mass concentration of the one-dimensional material and the liquid metal system.

[0023] Optionally, the elastic substrate is prepared by the following method:

[0024] Adding a reaction accelerator to a mixture containing a prepolymer and an initiator to obtain a pre-gel solution, which is then solidified and swelled in water to obtain an elastic substrate;

[0025] Optionally, the prepolymer comprises acrylamide.

[0026] Optionally, the prepolymer further comprises at least one of hyaluronic acid and sodium alginate.

[0027] Optionally, the mixed solution further contains at least one of calcium chloride and calcium sulfate.

[0028] Optionally, the initiator is selected from ammonium persulfate;

[0029] Optionally, the reaction accelerator is selected from N, N, N', N'-tetramethylethylenediamine;

[0030] Optionally, the curing conditions include: a radiation light wavelength of 365 nm and a radiation time of 0.2 to 1 h.

[0031] According to another aspect of the present application, there is provided an application of the above-mentioned ultra-stretchable polymer conductive material in flexible electronic devices and minimally invasive interventional surgery.

[0032] Optionally, the electronic device includes an electromagnetic actuator and an electromagnetic clamp.

[0033] The beneficial effects of this application include:

[0034] The ultra-stretchable polymer conductive material provided in this application utilizes a novel design strategy for stretchable conductor structures that mimics the specific deformable properties of rigid island-bridge devices, delegating the task of stretchability to a deformable liquid metal (LM) while maintaining the integrity of the one-dimensional interconnect under large strains. Therefore, most of the deflection of the soft island-bridge structure is mediated by liquid metal-based and island deformation on an elastically supported linear backbone. On the integrated island-bridge structure, liquid metal fragments aggregate during stretching, facilitated by rearranged bridges, to form a conductive network. When the stretching force is released, the liquid metal fragments self-organize into a tortuous bridge-skeleton network with an average zero-strain conductivity resistance of 1.4Ω. The autonomously formed topology of the soft island bridges helps maintain a nearly constant resistance, resulting in a volume conductivity of 2.6×105 S / cm at >2200% strain. In the application of the ultra-stretchable polymer conductive material of this application, the strong island bridge conductor exhibits the bending elasticity of the electromagnetic clamp and the stretching durability of the vascular-scale robot. This scalable and adjustable design strategy enables the integration of different materials in a single device, allowing various applications in stretchable electronics, opening up new avenues for the design and application of the next generation of ultra-stretchable electronics. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a SEM image of Comparative Example 2 of the present application and an energy dispersive spectrum (EDS) of the Ag bridge structure, with a scale bar of 100 nm.

[0036] FIG2 is a SEM image of Comparative Example 1 of the present application and an energy dispersive spectrum (EDS) of the island structure, with a scale bar of 100 nm.

[0037] FIG3 is a SEM image of Example 1 of the present application and an energy dispersive spectrum (EDS) of the island-bridge structure, with a scale bar of 100 nm.

[0038] FIG4 is an SEM image of Example 1 of the present application and the energy dispersive spectrum (EDS) of the island-bridge structure in the unstretched state (a), stretched state (b) and a pair of the two, with a scale bar of 100 nm.

[0039] Figure 5 shows (a) Schematic diagrams of the "island-only" conductive material strategy with and without strain, (b) finite element analysis results of the surface stress distribution of the conductive material using the "island-only" strategy, (c) Schematic diagrams of the "bridge-only" conductive material strategy with and without strain, (d) finite element analysis results of the current loss density of the conductive material using the "bridge-only" strategy, (e) Schematic diagrams of the "island-bridge" conductive material strategy with and without strain, (f) finite element analysis results of the current density of the conductive material using the "island-bridge" strategy, and (g) comparison of the conductivity and resistance changes of other stretchable conductive materials at maximum strain. Scale bar: 1 μm.

[0040] FIG6 is a reference diagram of an equivalent circuit diagram of a flexible island-bridge structure.

[0041] Figure 7 shows the relationship between (a) the relative change in conductor resistance of Comparative Example 1 using the "island only" and strain strategy, (b) the normalized resistance and strain of the "island only" conductor at 400 cycles under 200% strain, and (e) the relative change in conductor resistance of Examples 1 to 3 using the "bridge only" and strain strategy. The bridge includes AgNWs (black), AuNWs (yellow), and CNT (blue). (f) Under 200% strain, the resistance change of the "bridge-only" conductor using AgNWs (black), AuNWs (yellow), and CNT (blue) as the bridge, respectively. (f) The relative change of the conductor resistance adopts the "soft island bridge" and strain strategy. The soft island bridge includes Ag-Ga (black), Au-Ga (yellow), and CNT-Ga (blue). (g) Under 200% strain, the resistance change of the "soft island bridge" conductor using AgNWs (black), AuNWs (yellow), and CNT (blue) as the bridge, respectively.

[0042] FIG8 is a comparison of resistance changes under different one-dimensional nanomaterial dosages and different liquid metal mass concentrations in Example 1 and Examples 4 to 23.

[0043] FIG9 shows the change in resistance and conductivity of the ultra-stretched polymer conductive material of Example 1 with tensile strain (R is the resistance in the stretched state, and R0 is the resistance in the zero strain state)

[0044] Figure 10 shows the application of the ultra-stretched polymer conductive material of the present application as an interconnector, (a) is a schematic diagram of the application in a signal transmission test system, (b) is the stability of signal transmission of the ultra-stretched polymer conductive material under a series of deformations of 0%-500%, and (c) and (d) are the stability of signal transmission of the island conductor and the bridge conductor under a series of deformations of 0%-500%.

[0045] Figure 11 shows the surface morphology changes of (a) the island-bridge structure, the island structure alone, and the bridge structure alone under different strains for Examples 1-3 of the present application. (b)-(d) SEM images of the materials of Examples 1-3 at 0% strain (scale bar: 1 mm), 500% strain (scale bar: 100 μm), and a magnified SEM image of a portion at 500% strain (scale bar: 5 μm).

[0046] Figure 12 shows the resistance change rate of the ultra-stretchable polymer conductive material (a) in the undeformed and deformed states, while applying different pressures (F = 2N, 5N, 10N) to the pressure sensor. b. The functional relationship between the resistance change rate and the applied force. DETAILED DESCRIPTION

[0047] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0048] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0049] Unless otherwise specified, conventional methods were used for testing, and instrument settings were those recommended by the manufacturer.

[0050] LM (Ga 75.5%, In 24.5%, conductivity 34,000 S cm -1 ) were purchased from Sigma (USA); one-dimensional nanomaterials: AgNWs were purchased from Maogo Technology Co., Ltd. (Shanghai, China); carbon nanotubes and gold nanowires were purchased from XFNANO Materials Technology Co., Ltd. (Nanjing, China); hyaluronic acid, calcium chloride, N,N,N',N'-tetramethylethylenediamine (TEMED), acrylamide (AAm, ≥99%), N,N'-methylenebis(acrylamide) (MBAA, 99%), ammonium persulfate (APS), sodium alginate (SA, 99%), and calcium sulfate were purchased from Macklin (Shanghai, China). Deionized water (18.2 mΩ) was used in the experiments.

[0051] The surface morphology was characterized by SEM (Zeiss, UK); elemental analysis was performed by electron dispersion spectroscopy (EDS) and characterization was performed by scanning electron microscopy (SEM) using EDAX Genesis X4M; the resistance was measured using an LCR meter (Keysight Technologies, USA), and the resistance value (Ω) was averaged from ten measurements. The thickness was measured using a scanning electron microscope and the average value (μm) was taken from 12 measurements. The initial conductivity of the material was calculated as σ = l / Rwt, where l, w, t, and R are the length, width, thickness, and resistance of the conductor, respectively; electromechanical characterization was performed by transfer printing a rectangular specimen with a length of 30 mm and a width of 10 mm onto a VHB or PDMS substrate. In order to eliminate the interface resistance change between the LM-AgNw-based conductor and the external copper tape, LM was added at each end of the sample for electrical connection. The electrical resistance of the elastic conductor under different tensile states was measured using an LCR meter. The sample was prepared into rectangular flat sheets (30 mm × 50 mm × 2 mm) and then cut into dumbbell-shaped specimens of known dimensions (4 mm × 10 mm) for tensile testing. The conductor was tested on a mechanical testing machine to obtain stress-tension curves and identify the shear modulus by fitting the experimental curves to the new Hookean model. Cyclic tensile tests were conducted on a uniaxial mechanical tensor at a low strain rate of 10 mm / min. Finite element modeling was performed using the 3D finite element method (FEM) and COMSOL Multiphysics 6.0 software. In the current module, a DC voltage of 100 V was defined and connected to the right end of the silver nanowire at the boundary, while the left end of the silver nanowire at the boundary was grounded. The current density and directional distribution of the model were calculated using the current interface. Basic parameters: Silver nanowire radius: r = 40nm EGaIn ellipsoid major axis: 0.35μm and 0.15μm Substrate side length: 5.4μm Substrate side width: 2.6μm EGaIn conductivity: 8.3×106S / m Silver nanowire conductivity: 6.16×107S / m.

[0052] Example 1 Preparation of ultra-stretchable polymer conductive material based on silver bridge

[0053] (1) Preparation of substrate:

[0054] We dissolved the specified amounts of AAm, SA, and APS (initiator) in deionized water and then added TEMED (reaction accelerator). The precursor solution was then injected into a reaction cell consisting of two acyclic plates separated by a 1mm-thick acrylic spacer. The plates were exposed to a 365nm UV irradiator for half an hour to polymerize, synthesizing a PAAM-SA hydrogel elastic substrate. The prepared hydrogel substrate was swollen in a large amount of water, the residue was removed, and equilibrium was achieved at room temperature.

[0055] (2) Preparation of flexible island-bridge structure layer:

[0056] A 1.5 cm x 1.5 cm PAAM-SA hydrogel elastic substrate was cut and treated with UV ozone activation for 15 minutes. A one-dimensional nanomaterial solution (silver nanowire content 1 mg / mL) was then dripped directly onto the surface of the elastic substrate using a pipette. The sample was then placed in a vacuum chamber to dry and remove excess water. The one-dimensional material solution was then dripped directly onto the surface of the elastic substrate using a pipette again, and the sample was placed in a vacuum chamber to dry and remove excess water, forming a one-dimensional conductive layer. Liquid metal LM (mass concentration 6.25 wt%) was then spin-coated onto the one-dimensional conductive layer and manually sintered to obtain the ultra-stretchable polymer conductive material.

[0057] Example 2 Preparation of ultra-stretchable polymer conductive material based on gold bridge

[0058] The preparation process is the same as that of Example 1, except that gold nanowires are used as the one-dimensional nanomaterial.

[0059] Example 3 Preparation of ultra-stretchable polymer conductive materials based on carbon bridges

[0060] The preparation process is the same as that of Example 1, except that carbon nanotubes are used as the one-dimensional nanomaterial.

[0061] Examples 4 to 23

[0062] The preparation process was the same as that in Example 1, except that the silver nanowire contents were 1 mg / ml, 2 mg / ml, 3 mg / ml, and 4 mg / ml, respectively, and the mass concentrations of the liquid metal LM were 1.5625 wt%, 3.125 wt%, 6.25 wt%, 12.5 wt%, and 25 wt% under each silver nanowire content.

[0063] Comparative Example 1 Eutectic Gallium Indium (EGaIn) Island Structure Conductive Material

[0064] (1) Preparation of substrate: same as in Example 1;

[0065] (2) Preparation of island structure layer: Cut a 1.5 cm × 1.5 cm PAAM-SA hydrogel elastic substrate and treat it with UV ozone activation for 15 min. Then, place the sample in a vacuum chamber to dry and remove excess moisture. LM is injected into the template mask and brushed onto the elastic substrate.

[0066] Comparative Example 2 One-dimensional structure conductive material

[0067] (1) Preparation of substrate: same as in Example 1;

[0068] (2) Preparation of one-dimensional structural layers:

[0069] A 1.5 cm × 1.5 cm PAAM-SA hydrogel elastic substrate was cut, pre-stretched by 50%, and treated with UV ozone activation for 15 minutes. A one-dimensional nanomaterial (silver nanowire) solution was dripped directly onto the surface of the elastic substrate using a pipette, and then the sample was placed in a vacuum chamber to dry and remove excess moisture from the surface. The elastic substrate was then rotated 90° and pre-stretched by 50% again. The one-dimensional material solution was dripped directly onto the surface of the elastic substrate using a pipette again, and then the sample was placed in a vacuum chamber to dry and remove excess moisture to form a one-dimensional conductive layer.

[0070] From the surface morphology in Figures 1 and 2, it can be seen that for the elastic materials of Comparative Example 2 with only bridges and Comparative Example 1 with only isolated islands, the hard oxide layer around the liquid metal hinders firm contact with the substrate. Figure 3 shows the difference between the island bridge structure and the one without island bridges in Example 1, where the cross-linked particles appear denser and the exposed surface area is smaller. The interwoven network structure of the island bridge structure densely covers the surface of the hydrogel, resulting in a significant reduction in visible pores in the EDS mapping. Observe the structural deformation of In-Ag before and after stretching. (Figure 4). In the initial state, the dispersed liquid metal is entangled with the silver nanowires and presents an aggregated state (Figure 4a). During stretching, the liquid metal is pulled by the silver bridge and gradually merges into a larger dense structure (Figure 4b, Figure 4c).

[0071] Eutectic gallium indium (EGaIn) is an attractive intrinsic elastic material due to its high liquid fluidity, high conductivity and low toxicity. Figure 5a shows a schematic diagram of the island structure conductor used in Comparative Example 1. Initially, the liquid metal atoms are densely packed together. However, increasing the stress weakens the atomic bonds, causing the conductive path to fail. This also leads to the following limitations: low initial conductivity, low cyclic stability, low maximum strain, cumbersome manufacturing and fragile sealing. In Figure 5b, finite element modeling of only the island conductor is performed. The unnecessary formation of the oxide layer tends to be electrically insulating, and because it tends to impart adhesion and non-Newtonian properties, the delamination behavior further hinders the formation of the conductive path during the strain process.

[0072] One-dimensional nanomaterials ensure a direct conductive path, and the aspect ratio of the conductive material reduces the critical density, so they can achieve high conductivity with less material. However, the direct manufacture of elastic conductors using one-dimensional nanomaterials is hindered by severe agglomeration problems and requires additional mechanical sintering to form conductive junctions. Figure 5d shows a schematic diagram of the one-dimensional linear structure used in Comparative Example 2, and shows a one-dimensional linear material arranged in an ordered manner to form a conductive percolation network. However, due to the lack of strong and effective bonding connections between the linear materials, the conductivity decreases under tensile strain, and electrical failure caused by slip in the oriented one-dimensional nanomaterial occurs (Figure 5c).

[0073] Figure 5e is a schematic diagram of the flexible island-bridge structure used in Example 1. The concept of this structure involves deformable electronically conductive islands connected by rigid conductive bridges. During significant deformation, the island-bridge structure generates a compensation mechanism to keep the charge flowing stably through the structure. The liquid metal coalesces into larger droplets as islands, while the silver nanowires at both ends of the droplets and the parts extending from the edges of the droplets act as bridges connecting the islands. The proposed island-bridge structure focuses on fixing non-stretchable components and limiting strain to stretchable interconnects to achieve stretchability. Under severe stretching, the ultra-long wires reach their limits, and the inherent properties of liquid metal lead to additional stretchability enhancement and maintained conductivity. Compared with other stretchable electronic design strategies, the electromechanical performance of soft island bridges stands out. Combining high initial conductivity, large stretchability, and increased conductivity at extreme elongation, soft island bridges have unparalleled performance among stretchable conductors, as shown in Figure 5g.

[0074] The equivalent circuit diagram of the flexible island-bridge structure used in Example 1 is shown in FIG6 , where R a 、R b and R c are the resistances of the soft island, bridge, and soft island-bridge structures, respectively. Equations:

[0075] During the stretching process, the adjacent overlapping area changes, making the contact resistance R a As the strain increases, the gaps between islands become larger, increasing the electron migration path and causing the resistance (R b ) increases. However, the resistance of the conductor remains robust because the oxide film of the liquid metal droplets in these composites breaks down, the liquid metal flows out, and forms new connections with the adjacent solid conductive filler. This stable structure acts as a buffer mechanism, helping to stabilize the resistance R c The associated current density map shows the path of electrons entering the island region (Figure 5f). By measuring the theoretical resistance of each structure, the resistance of the soft island bridge is indeed lower than that of the representative non-island bridge design. This soft island bridge innovation subverts the traditional concept of soft interconnection and endows patterned elastic conductors with high electrical performance and electrochemical stability during mechanical deformation.

[0076] Test Example 1

[0077] The dotted line graph in Figure 7e shows the bridges stretched to 1000% strain and their resistance change (R / R0). According to Paulet's law, the bridge resistance change is positively correlated with the applied strain, indicating the formation of a conductive percolation network of nanoscale bridges. Figure 7f shows the contact resistance of each bridge during 100 cycles of uniaxial tensile testing. The silver bridge, gold bridge, and carbon bridge fluctuate regularly within the range of 1000Ω-3500Ω (silver bridge), 3800Ω-9000Ω (gold bridge), and 900Ω-5700Ω (carbon bridge), respectively. This indicates that in the first stage of the buffering mechanism, the rearranged bridges are stably attached to the substrate. The dynamic conductive pathways generated by the liquid metal fragments maximize the resistance change of the isolated island conductors, resulting in an R / R0 at 1000% strain that is 1050 times that at 0% strain (Figure 7a). The islands fluctuate on the substrate, with the resistance varying from 1150Ω to 3000Ω. During 100 cycles of tensile testing, the strain reached up to 200% (Fig. 7b).

[0078] In Figure 7g, a conductor with an island-bridge structure exhibits resistance changes that are insensitive to strain within the range of 500 Ω. Subsequently, the resistance increases abruptly by 1–4 orders of magnitude before stabilizing. Furthermore, it is noteworthy that In-CNTs exhibit no significant resistance change, with a resistance change of 3.5 Ω at 1000% strain. Using these thresholds, simple resistance measurements can serve as a functional memory of the maximum strain in the island bridges even after repeated elongation. In Figure 7h, the island bridges retain strain memory after 100 cycles of elongation, a fact that suggests that the rupture of some particles is controlled by a strain / energy threshold that does not fatigue. The zero-state resistance of this sample after 1 cycle to 200% strain (3 Ω) and after 100 cycles to 200% strain (9 Ω) is shown. The strain-induced resistance change is small, resulting in lower prediction fidelity. However, a clear inflection point and resistance drop can still be observed when measuring resistance versus strain beyond the previous maximum strain.

[0079] The electrical properties of the resulting conductors were investigated at different weight ratios (Figure 8). As the LM mass loading and AgNW concentration loading increased, the resistance change of the island bridge stretchable conductor gradually became gentler. The resistance change of the island bridge was ultimately maintained at around 1.5, and the elongation exceeded 2200%. (Figure 9)

[0080] Test Example 2

[0081] To test the resolution of pressure measurements of strain on a conductor, a pressure sensing system was constructed, as shown in Figure 10a. The electrical property of each conductor is defined as ΔR' / R0', where R' is the total resistance of the entire circuit under deformation, R0' is the initial resistance without deformation, and ΔR' is the change in resistance during deformation, given by ΔR' = (R' - R0'). The rate of change of the connected island bridges during repeated stretching is consistent across different strains. The signal transmission test method is as follows: First, different sections of the stretchable conductor are connected in series with a resistive pressure sensor within the circuit. Then, the resistive sensor is repeatedly pressed during seven load-unload cycles while the stretchable conductor is subjected to varying strains from 0% to 500%. This process allows for multiple tests to assess the stability of signal transmission. Figure 10b shows the resistance change in the circuit of an In-Ag stretchable conductor under dynamic strains from 0% to 500%. The sensor's response to pressure is nearly instantaneous and highly repeatable with each application of pressure across all cycles. The conductance response upon pressure loading remains constant within the experimental resolution and returns to its initial level upon pressure unloading. In particular, referring to Figure 10b, the relative change in conductance under 8 N of applied pressure is 95%, with a standard deviation σ of 0.005%. Figure 11a shows the morphology of the various phases of the island-bridge structure. This is because the liquid-phase EGaIn is able to follow any changes in the shape of the stretched hydrogel matrix. The EGaIn is connected by silver nanowires to maintain a continuous conduction pathway through the linear backbone (Figure 11b). In stark contrast, this demonstrates that the high-aspect-ratio nanowires promote the stretchability of the liquid metal. The alloying reaction also ensures EGaIn's affinity for the substrate.

[0082] The electrical responses to the same normal pressure are almost the same in the tensile strain range of 0 to 500%. Fig. 12 shows that the applied normal pressure can be detected and is linearly dependent on the electrical response under various tensile strains. After the loading-unloading cycle, the conductivity response amplitude corresponding to the 2N, 5N, and 10N normal pressure loading was maintained (Fig. 12a), and Fig. 12b shows the functional relationship between the resistance change and the applied force, verifying the reliability of the pressure measurement. When used only as a signal transmission medium, the island bridge and the bridge only exhibited a fluctuating electrical response in the strain range of 0% to 500% (Fig. 10c-10d). The conductor without the island bridge structure formed an isolated granular morphology after being stretched to 500% (Fig. 11c-11d)

[0083] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A super-stretchable polymer conductive material, characterized in that The ultra-stretchable polymer conductive material comprises a plurality of one-dimensional nanomaterials and a plurality of liquid metal fragments; The one-dimensional nanomaterials are connected by liquid metal fragments to form a conductive network with a linear skeleton and a flexible island-bridge structure; In the island-bridge structure, the liquid metal fragments are islands and the one-dimensional nanowires are bridges; When the ultra-stretchable polymer conductive material is stretched under stress, liquid metal fragments self-organize, aggregate, or break to maintain the resistance stability of the conductive network.

2. The ultra-stretchable polymer conductive material according to claim 1, characterized in that The volume conductivity of the ultra-stretchable polymer conductive material is greater than 2.6×10 5 S / cm.

3. The ultra-stretchable polymer conductive material according to any one of claims 1 to 2, characterized in that: The one-dimensional nanomaterial has a length of 5 to 100 μm.

4. The ultra-stretchable polymer conductive material according to any one of claims 1 to 3, characterized in that: The weight ratio of the one-dimensional nanomaterial to the liquid metal fragments in the ultra-stretchable polymer conductive material is 1:0.35-25.

5. The ultra-stretchable polymer conductive material according to any one of claims 1 to 4, characterized in that: The one-dimensional nanomaterial is selected from at least one of gold nanowires, silver nanowires, and carbon nanotubes.

6. The ultra-stretchable polymer conductive material according to any one of claims 1 to 5, characterized in that: The liquid metal is selected from eutectic gallium and indium.

7. The ultra-stretchable polymer conductive material according to any one of claims 1 to 6, characterized in that: The ultra-stretched polymer conductive material further includes an elastic substrate, and the conductive network is deposited on the surface of the elastic substrate.

8. The ultra-stretchable polymer conductive material according to any one of claims 1 to 7, characterized in that: The elastic substrate is a hydrogel.

9. The method for preparing the ultra-stretchable polymer conductive material according to any one of claims 1 to 8, characterized in that: The steps include: S1, coating the one-dimensional nanomaterial dispersed in the aqueous solution on the surface of the elastic substrate, and vacuum drying to form a one-dimensional conductive layer; S2. Spin-coating liquid metal on the one-dimensional conductive layer obtained in step S1 to obtain an ultra-stretchable polymer conductive material through self-assembly.

10. The preparation method according to claim 9, characterized in that The content of the one-dimensional nanomaterial in the raw material solution is 1-4 mg / mL.

11. The preparation method according to any one of claims 9 to 10, characterized in that: The mass concentration of the liquid metal on the ultra-stretched polymer conductive material after spin coating is 1.5-25 wt %.

12. The preparation method according to any one of claims 9 to 11, characterized in that: The elastic substrate is prepared by the following method: A reaction accelerator is added to a mixed solution containing a prepolymer and an initiator to obtain a pre-gel solution, which is then solidified and swelled in water to obtain an elastic substrate.

13. The preparation method according to any one of claims 9 to 12, characterized in that: The prepolymer comprises acrylamide.

14. The preparation method according to any one of claims 9 to 13, characterized in that: The prepolymer further comprises at least one of hyaluronic acid and sodium alginate.

15. The preparation method according to any one of claims 9 to 14, characterized in that: The initiator is selected from ammonium persulfate.

16. The preparation method according to any one of claims 9 to 15, characterized in that: The reaction accelerator is selected from N, N, N', N'-tetramethylethylenediamine.

17. The preparation method according to any one of claims 9 to 16, characterized in that: The curing conditions include: a radiation light wavelength of 365 nm and a radiation time of 0.2 to 1 hour.

18. Use of the ultra-stretchable polymer conductive material according to any one of claims 1 to 8 in flexible electronic devices and minimally invasive interventional surgery.

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