Preparation method, product and application of composite nanofiber membrane

Abstract

The invention relates to the technical field of electrostatic spinning, in particular to a preparation method, a product and application of a composite nanofiber membrane. The preparation method comprises the following steps: depositing a liquid metal nanoparticle suspension and a polymer solution on a collection plate in electrostatic spraying and electrostatic spinning modes to prepare a base material; and carrying out ultrasonic impregnation on the matrix material to obtain the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane. According to the preparation method combining electrostatic spinning with electrostatic spraying, liquid metal nanoparticles are anchored to the fibers, the particles and the fibers can intersect in the air under the action of a conjugate electric field, and therefore the particles can be loaded in the fibers more evenly. The ultrasonic impregnation method improves the loading capacity of the liquid metal nanoparticles on the surface of the liquid metal nanoparticle composite nanofiber, and the two processes supplement each other to promote uniform dispersion of the liquid metal nanoparticles in the fiber.

Description

Technical Field

[0001] The present invention relates to the technical field of electrostatic spinning, and in particular to a preparation method, product and application of a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane. Background Art

[0002] Surface enhanced Raman scattering (SERS) spectroscopy is a powerful analytical tool for identifying molecules by providing fingerprint vibrational modes with ultra-high sensitivity. One of the main problems in SERS detection is to construct substrates that have both high surface enhanced Raman spectroscopy activity and good SERS signal reproducibility. For practical applications, a desired substrate should show a very uniform signal (signal deviation less than 10%) over the entire active area of ​​the substrate.

[0003] As a convenient and versatile technology, electrospinning technology has been developed for the large-scale production of ultrafine polymer nanofiber membranes embedded with plasmonic nanoparticles. Using this technology, various shape-controlled plasmonic nanoparticles with significant optical properties, such as Ag nanospheres, Au nanorods, Ag nanowires, and assemblies of Au nanorods and Ag nanowires, have been assembled into polymer (typically polyvinyl alcohol or polyacrylonitrile) nanofibers as economical and effective SERS substrates. However, the existing active materials with noble metals such as gold, silver, and copper as SERS substrates generally have the contradiction between sensitivity and stability (susceptible to environmental interference), adsorption restrictions on the molecules to be tested, and biocompatibility problems, making it difficult to achieve long-range uniform distribution of target molecules on nanostructures. Most SERS substrates composed of noble metal nanostructure arrays have been prepared by physical adsorption, emulsion spinning, coaxial spinning, and post-treatment. However, the above methods have problems such as uneven distribution of nanoparticles, difficult control of process parameters, and cumbersome operation steps, which limit the large-scale preparation of substrates with good SERS signal uniformity and are difficult to expand to large-scale conventional SERS detection. Therefore, how to develop a stable, cheap, large-scale and reliable SERS substrate is a technical problem that technicians in this field are committed to solving. Summary of the invention

[0004] Based on the above content, the present invention provides a preparation method, product and application of a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane to solve the problem of uneven dispersion of metal nanoparticles in the preparation of existing metal composite nanofiber membranes.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is a method for preparing a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane, comprising the following steps:

[0007] Depositing a liquid metal nanoparticle suspension and a polymer solution on a collecting plate by electrostatic spraying and electrostatic spinning respectively to prepare a matrix material, and ultrasonically impregnating the matrix material to obtain the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane;

[0008] The needle of the electrostatic spray is arranged vertically to the needle of the electrostatic spinning;

[0009] The electrostatic spraying and the electrostatic spinning are performed simultaneously.

[0010] The present invention uses the fiber membrane prepared by electrospinning combined with electrospraying as the matrix material for subsequent ultrasonic impregnation of liquid metal nanoparticles. Under the action of ultrasound, the liquid metal nanoparticles are evenly dispersed on the surface of the fiber membrane.

[0011] The second technical solution of the present invention is a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane prepared according to the above-mentioned preparation method.

[0012] The third technical solution of the present invention is the application of the above-mentioned uniformly dispersed liquid metal nanoparticle composite nanofiber membrane in the preparation of a SERS substrate.

[0013] A fourth technical solution of the present invention is a SERS substrate, the raw material of which includes the above-mentioned uniformly dispersed liquid metal nanoparticle composite nanofiber membrane.

[0014] The present invention discloses the following technical effects:

[0015] The present invention anchors liquid metal nanoparticles on fibers through a preparation method combining electrostatic spinning with electrostatic spraying (conjugated electrospinning), and utilizes the effect of a conjugated electric field (the electric field formed by electrospinning interacts with the electric field formed by electrospraying) to allow the particles and fibers to intersect in the air, thereby allowing the particles to be more evenly loaded on the fibers to prepare a matrix material. The ultrasonic impregnation method increases the loading amount of liquid metal nanoparticles on the surface of the liquid metal nanoparticle composite nanofiber membrane, and the matrix constructed by combining electrospinning with electrospraying promotes the uniform distribution of liquid metal nanoparticles inside the fibers. The two processes (conjugated electrospinning and ultrasonic impregnation) complement each other, and the SERS hotspot distribution of the SERS substrate constructed by combining the two processes is more uniform, and the SERS performance is greatly enhanced due to the provision of more SERS hotspots.

[0016] The method of the present invention can be used to prepare a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane, thereby solving the problem of uneven dispersion of nanoparticles in the preparation of existing multiple composite films.

[0017] The uniformly dispersed liquid metal nanoparticle composite nanofiber membrane of the present invention can be used as a flexible SERS substrate with antibacterial properties, and has the characteristics of good uniformity and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a schematic diagram of a device for preparing a matrix material using a conjugate electrospinning method in Example 1 of the present invention.

[0020] Figure 2 These are the electric field simulation distribution diagrams of the matrix material prepared by the conjugated electrospinning method in Example 1 of the present invention; wherein, (a) is the electric field line distribution diagram at a lateral distance of 60 cm, (b) is the electric field line distribution diagram at a lateral distance of 80 cm, (c) is the electric field line distribution diagram at a lateral distance of 100 cm, and (d) is the potential distribution diagram at different lateral distances (60, 80, 100 cm).

[0021] Figure 3 These are the SEM and EDS mapping images of the base material prepared in Example 1 of the present invention.

[0022] Figure 4 These are the SEM and EDS mapping images of the liquid metal nanoparticle composite nanofiber membrane prepared in Example 2 of the present invention.

[0023] Figure 5 The stability and sensitivity of the SERS substrates prepared in Examples 1-4 of the present invention are verified in Figures; (a) is the SERS spectrum of R6G collected on the SERS substrates prepared in Examples 1-4, (b) is the SERS spectra of R6G at three different points on the E-Au@LM-PI SERS substrate, and (c) is the SERS spectra of three points on the E-Au@LM-PI SERS substrate at 614 cm -1 Intensity plot of the peak at . DETAILED DESCRIPTION

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0026] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0027] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0028] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0029] The first aspect of the present invention provides a method for preparing a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane, comprising the following steps:

[0030] Depositing a liquid metal nanoparticle suspension and a polymer solution on a collecting plate by electrostatic spraying and electrostatic spinning respectively to prepare a matrix material; ultrasonically impregnating the matrix material to obtain the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane;

[0031] The needle of the electrostatic spray is arranged vertically to the needle of the electrostatic spinning;

[0032] The electrostatic spraying and the electrostatic spinning are performed simultaneously.

[0033] The orthogonal arrangement (90°) of the electrostatic spray needle and the electrostatic spinning needle can make the interaction between particles and fibers more complete. The electrostatic spinning needle is perpendicular to the collecting plate. This placement can make the fiber formation more uniform and stable during the electrospinning fiber deposition process. The electrostatic spray needle is parallel to the collecting plate, so that the electrospray particles can be more evenly dispersed in the fiber. The deflection angle will affect the unevenness of the electric field distribution and affect the stability during spraying and spinning. 60° (when the electrostatic spinning needle is perpendicular to the collecting plate, the angle between the electrostatic spray needle and the electrostatic spinning needle is 60°) will greatly affect the linear jet stage during the fiber formation process, thereby affecting the stability of the jet during fiber deposition and causing the phenomenon of flying silk. The angle of 120° (when the electrostatic spinning needle is perpendicular to the collecting plate, the angle between the electrostatic spray needle and the electrostatic spinning needle is 120°) will affect the solidification process of the fiber, thereby destroying the uniform distribution of fiber deposition and causing the fibers to stick together into beads. Therefore, the present invention stipulates that the needle of electrostatic spraying and the needle of electrostatic spinning are arranged orthogonally (90°).

[0034] In a preferred embodiment of the present invention, the method for preparing the liquid metal nanoparticle suspension comprises the following steps:

[0035] The liquid metal and the stabilizer are added to a solvent for ultrasonic treatment, followed by centrifugation, and the obtained supernatant is the liquid metal nanoparticle suspension.

[0036] In a preferred embodiment of the present invention, the liquid metal is a gallium-indium alloy.

[0037] The natural thin oxide layer (0.7-3nm) of gallium-based liquid metal nanoparticles avoids the disadvantages of unstable chemical properties and easy agglomeration of metal nanoparticles. Its surface plasmon can be extended to the deep ultraviolet region, which completely solves the problem of environmental (fluorescence) interference. In addition, gallium nanoparticles are locally confined on the surface or inside of high-porosity nanofibers to form rich three-dimensional SERS "hot spots"; and the large specific surface area of ​​self-supporting three-dimensional porous structure fibers is easy to fully contact with the detected object (providing more adsorption sites), achieving the purpose of stable, uniform, and highly sensitive SERS detection.

[0038] In a preferred embodiment of the present invention, the stabilizer is at least one of polyvinyl pyrrolidone, polyoxyethylene polyoxypropylene ether F127, dodecyl mercaptan, sodium dodecylbenzene sulfonate or N,N-dimethylacetamide. In a further preferred embodiment of the present invention, the stabilizer is polyvinyl pyrrolidone.

[0039] The concentration of the stabilizer has little effect on the liquid metal nanoparticle suspension. The concentration of the stabilizer is preferably such that the liquid metal nanoparticles can be fully dispersed. For this reason, the present invention selects a correspondingly smaller stabilizer concentration; the mass ratio of the stabilizer to the liquid metal is 1:10.

[0040] In a preferred embodiment of the present invention, the mass volume ratio of the liquid metal to the solvent is 1g:(15-25)mL; the solvent is one of anhydrous ethanol, acetone, and dimethylformamide; the centrifugal speed is 1000r / min-4000r / min, and the time is 0-60min.

[0041] The present invention limits the mass volume ratio of the solvent to the liquid metal, the ultrasonic speed and the ultrasonic time within the above range, which can fully split, crush and oxidize the liquid metal to form nanoparticles with uniform particle size distribution. In the present invention, during the ultrasonic process, the liquid metal is crushed, an oxidation reaction occurs on the surface of the liquid metal particles, and then centrifuged to form a uniform and stable liquid metal nanoparticle suspension. Thereby, the liquid metal nanoparticles can be evenly dispersed among the fibers. When the mass volume ratio of the liquid metal to the solvent and the rotation speed exceed the range recorded above, it will affect the uniformity and stability of the particle size distribution of the liquid metal particles in the liquid metal nanoparticle suspension, thereby affecting the uniformity of the distribution of the liquid metal nanoparticles in the prepared composite nanofiber membrane, and further affecting the stability and sensitivity of the composite nanofiber membrane as a SERS substrate.

[0042] In a preferred embodiment of the present invention, the polymer in the polymer solution is at least one of polyvinyl alcohol, polyethylene oxide, polyimide or polyvinylidene fluoride; the solvent of the polymer solution is water; and the concentration of the polymer in the polymer solution is 5-15%.

[0043] In a preferred embodiment of the present invention, the lateral distance between the needle of the electrostatic spray and the needle of the electrostatic spinning is 60 to 120 mm, and the height difference is 30 to 60 mm.

[0044] The present invention sets the lateral distance and height difference between the needle of the electrostatic spray and the needle of the electrostatic spinning within the above parameter range, which can make the liquid metal nanoparticles more evenly dispersed in the fiber. Too much lateral distance will make the particles unable to fully interact with the fiber, so that fewer particles interact with the fiber, resulting in too little particle content. Too high or too low height difference will affect the stability of electrospraying and electrospinning, thereby destroying the uniformity of particle dispersion. Therefore, the present invention preferably limits the lateral distance between the needle of the electrostatic spray and the needle of the electrostatic spinning to 60 to 120 mm, and the height difference to 30 to 60 mm.

[0045] In a preferred embodiment of the present invention, the polymer solution is transferred to syringe 1 and the liquid metal nanoparticle suspension is transferred to syringe 2 and connected to the positive and negative electrodes of the power supply respectively; the needle of the electrostatic spraying and the needle of the electrostatic spinning are placed orthogonally (vertically) and voltage is applied, the lateral and longitudinal distances between the two nozzles are adjusted, and electrospinning and electrostatic spraying are performed simultaneously on a collecting plate to prepare a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane.

[0046] The electrostatically sprayed liquid metal nanoparticles and the electrostatically spun nanofibers intersect in the air, which can ensure that the surface of the nanofiber membrane is evenly loaded with liquid metal nanoparticles.

[0047] The voltage of the electrospinning is +12kv, the injection speed is 0.4ml / h, the receiving distance is 10cm, and the time is 1h; the voltage of the electrostatic spray is -4 to -12kv, the injection speed is 0.4 to 1.2ml / h, and the time is 1h; the needle of the electrostatic spray is located between the needle of the electrospinning and the collecting plate.

[0048] The ultrasonic impregnation specifically comprises: immersing the base material in a liquid metal nanoparticle suspension for ultrasonic treatment; the power of the ultrasonic treatment is 200W to 300W, and the time is 10min to 60min.

[0049] The present invention provides a method for preparing uniformly dispersed liquid metal nanoparticle composite nanofiber membrane in one step. The present invention applies opposite polarity voltage to an electrostatic spray nozzle and an electrostatic spinning nozzle through a conjugate electrospinning method, so that the electrospun fibers and the electrosprayed nanoparticles are cross-linked in the air. The liquid metal nanoparticles can be uniformly loaded on the nanofiber membrane through the regulation of process parameters. The nanofibers are used as a matrix to make the liquid metal nanoparticles more evenly distributed, prevent the nanoparticles from agglomerating, thereby improving the performance of the nanoparticles. The nanoparticles modify the surface of the nanofibers to improve the performance of the nanofibers, and simultaneously realize the multifunctionality of the nanofibers and nanoparticles. The ultrasonic impregnation method increases the loading amount of the liquid metal nanoparticles on the surface of the liquid metal nanoparticle composite nanofiber membrane. The matrix constructed by electrospinning combined with electrospraying promotes the uniform distribution of the liquid metal nanoparticles inside the fibers. The two processes complement each other. The SERS hotspot distribution of the SERS substrate constructed by combining the two processes is more uniform, and the SERS performance is greatly enhanced due to the provision of more SERS hotspots. The uniformly dispersed liquid metal nanoparticle composite nanofiber membrane prepared by the present invention can be used as a flexible SERS substrate with antibacterial properties, uniformity and stability for rapid detection of trace substances.

[0050] The second aspect of the present invention provides a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane prepared according to the above-mentioned preparation method.

[0051] The third aspect of the present invention provides the use of the above-mentioned uniformly dispersed liquid metal nanoparticle composite nanofiber membrane in the preparation of a SERS substrate.

[0052] A fourth aspect of the present invention provides a SERS substrate, the raw material of which includes the above-mentioned uniformly dispersed liquid metal nanoparticle composite nanofiber membrane.

[0053] The "room temperature" and "normal temperature" mentioned in the present invention, unless otherwise specified, all mean 15-20°C.

[0054] Unless otherwise specified, the raw materials used in the embodiments of the present invention can be obtained through commercial sources.

[0055] The gallium-indium alloy used in the embodiment of the present invention is EGa75In25.

[0056] The liquid metal nanoparticle suspension (LM NPs) used in the embodiment of the present invention is prepared by the following steps: 0.5g EGa75In25 is added to a 20ml sample bottle, 10ml anhydrous ethanol and 0.05g polyvinyl pyrrolidone (stabilizer) are added, and the probe is inserted into the ethanol for ultrasonic treatment using a Weiheng ultrasonic cell disruptor (model KC-500W), and the ultrasonic treatment is carried out at 250W for 120min at room temperature. In order to reduce the uncertainty of temperature, the water temperature is carefully controlled: a thermometer is placed in the water bath to detect the temperature change, and the water is changed every 10min to ensure that the water temperature is within 20°C. After ultrasonic treatment, the suspension is placed in a high-speed centrifuge and centrifuged at 3000rpm for 30min. Large particles are deposited at the bottom, and the resulting supernatant is the liquid metal nanoparticle suspension for electrostatic spraying.

[0057] The concentration of the polyimide solution used in the embodiment of the present invention is 20 wt %, and the solvent is DMAc (dimethylacetamide).

[0058] The present invention will be further described below by way of examples.

[0059] The schematic diagram of the device for preparing uniformly dispersed liquid metal nanoparticle composite nanofiber membrane by conjugated electrospinning method in Example 1 of the present invention is as follows Figure 1 shown.

[0060] Example 1 (Preparation of Liquid Metal Nanoparticle Composite Nanofiber Membrane E-Au@LM-PI by Conjugated Electrospinning Assisted Ultrasonic Impregnation)

[0061] 1 mL of polyimide solution was taken and placed in a 1 ml syringe for electrospinning; a liquid metal nanoparticle suspension was placed in a 1 ml syringe for electrostatic spraying; the electrospinning needle and the electrostatic spray needle were placed vertically (the direction of the electrospinning needle was perpendicular to the collecting plate, and the direction of the electrostatic spray needle was parallel to the collecting plate), the lateral distance between the two was set to 100 mm, and the height difference was set to 30 mm. A conjugate electrospinning method was adopted to provide a +12 kv voltage to the electrospinning needle and a -4 kv voltage to the electrostatic spray needle. The electrospinning and electrostatic spray injection speeds were adjusted respectively, and the electrostatic spray injection speed was set to 1.2 ml / h, and the electrospinning injection speed was set to 0.4 ml / h. The receiving distance between the electrospinning needle and the collecting plate (with aluminum foil on the collecting plate) was set to 10 cm. Electrospinning and electrostatic spraying were performed simultaneously for 1 hour, and the matrix material was deposited on the collecting plate.

[0062] The substrate material was immersed in a liquid metal nanoparticle suspension for ultrasonic treatment, so that the liquid metal nanoparticles were evenly loaded on the surface of the substrate material, and dried at room temperature to obtain a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane E-Au@LM-PI as a substrate; wherein the process parameters of the ultrasonic treatment were set to: time 30min, power 250w. The prepared substrate was subjected to gold spraying to construct the E-Au@LM-PI SERS substrate.

[0063] On the basis of Example 1, the present invention also verifies the electric field simulation distribution and potential distribution under the conditions that the lateral distance between the electrospinning needle and the electrostatic spray needle is 60 cm and 80 cm (that is, except for the lateral distance, the other step parameters are the same as those in Example 1). The results are as follows Figure 2 shown.

[0064] Example 2 (Preparation of Liquid Metal Nanoparticle Composite Nanofiber Membrane Au@LM-PI by Ultrasonic Impregnation Method)

[0065] 1 mL of polyimide solution was taken and placed in a 1 ml syringe for electrospinning. A +12 kV voltage was provided to the electrospinning needle, the injection speed was 0.4 ml / h, and the receiving distance between the electrospinning needle and the collecting plate (with aluminum foil on the collecting plate) was set to 10 cm. Polyimide nanofibers were deposited on the collecting plate.

[0066] The polyimide nanofibers were immersed in a suspension of liquid metal nanoparticles, and the liquid metal nanoparticles were evenly loaded on the surface of the polyimide nanofibers by ultrasonic treatment, and dried at room temperature to obtain a liquid metal nanoparticle composite nanofiber membrane Au@LM-PI as a substrate. The parameters of the ultrasonic treatment were set as: time 30min, power 250w. The prepared substrate was subjected to gold spraying to construct the Au@LM-PI SERS substrate.

[0067] Example 3 (Gold-plated Au-PI fiber membrane)

[0068] 1 mL of polyimide solution was placed in a 1 ml syringe for electrospinning, +12 kV voltage was provided to the electrospinning needle, the injection speed was 0.4 ml / h, the receiving distance between the electrospinning needle and the collecting plate (with aluminum foil on the collecting plate) was set to 10 cm, and polyimide nanofibers were deposited on the collecting plate. The polyimide nanofibers prepared by electrospinning were directly treated with gold spraying to construct Au-PI SERS substrates.

[0069] Example 4 (Si wafer gold-plated Au@Si)

[0070] The Au@Si SERS substrate was constructed by directly sputtering gold on a clean Si wafer.

[0071] The process parameters of the gold spraying treatment in the above embodiments 1-4 are the same, specifically as follows: the gold plating process adopts an ion sputtering apparatus (SBC-12 ion sputtering apparatus), the ion sputtering treatment process is carried out under vacuum, the sputtering current is always maintained at 10mA, the sputtering time is 3min, and the other sputtering parameters are all the default parameters of the instrument.

[0072] The electric field distribution of the electrospinning process of preparing uniformly dispersed liquid metal nanoparticle composite nanofiber membrane by conjugated electrospinning method in Example 1 was simulated and analyzed to reveal the mechanism of uniform preparation of composite thin film by conjugated electrospinning method. The electric field analysis was performed using comsol software, and the software modeling and simulation were as follows:

[0073] (1) Geometric model: The electric field distribution during electrospinning is obtained through simulation, and the devices that have little impact on the entire electrostatic field can be omitted. Finally, the entire working model of electrospinning can be simplified into three main parts: needle, receiving device, and shielding net. The model is simplified and a three-dimensional model is constructed. The shielding net, electrospinning needle and electrostatic spray needle are set respectively. The nozzle diameter is 0.6mm, the nozzle height is 10mm, and the shielding net range is a regular cube with a side length of 250mm. The height of the collecting plate is 200mm, the depth is 200mm, and the height is 10mm. The lateral and longitudinal distances between the electrospinning nozzle and the electrospray nozzle are set to (60, 80, 100mm) and 30mm, respectively. The final lateral distance was determined to be 100mm

[0074] (2) Parameter settings are shown in Table 1

[0075] Table 1

[0076] parameter Electrospinning nozzle Electrospray nozzle Collection Plate Shielding Net Relative dielectric constant 1 1 1 1 Material Stainless steel Stainless steel aluminum Air Boundary conditions 12000V -4000V 0V Grounding

[0077] The simulation results are as follows Figure 2 As shown by Figure 2The simulation result diagram can be used to deduce the electric field distribution of the conjugate electrospinning method. The electric field is interactively distributed when electrostatic spraying is combined with electrospinning. From this, it can be concluded that the nanoparticles can intersect with the electrospun nanofibers in the air, which can ensure that the fiber membrane is evenly dispersed with the loaded liquid metal particles.

[0078] The substrate prepared in Example 1 was subjected to scanning electron microscopy and EDS analysis, and the results are as follows: Figure 3 As shown (in the figure, the electron image 25 is a SEM image, and the rest are EDS mapping images), from Figure 3 The SEM image and EDS energy spectrum can confirm that in the fiber membrane (matrix material) prepared by electrospinning combined with electrostatic spraying (conjugated electrospinning method), the liquid metal nanoparticles are evenly dispersed on the nanofibers.

[0079] The liquid metal nanoparticle composite nanofiber membrane (SERS substrate) prepared by ultrasonic impregnation in Example 2 was subjected to scanning electron microscopy and EDS analysis. The results are as follows: Figure 4 As shown (in the figure, Electron Image 1 is a SEM image, and the rest are EDSmapping images), from Figure 4 It can be seen that by constructing the matrix material for subsequent ultrasonic impregnation through the conjugate electrospinning method, the uniformity of the distribution of liquid metal nanoparticles and the loading amount in the fiber are improved, which also provides more SERS hotspots and enhances its SERS performance.

[0080] Rhodamine 6G probe molecule was used to evaluate the sensitivity, uniformity and other properties of the composite nanofiber SERS substrate. Figure 5 As shown. By comparing Example 1 and Example 2, it can be seen that there are significant differences between the composite nanofiber membrane matrix materials prepared by conjugated electrospinning assisted ultrasonic impregnation and direct ultrasonic impregnation. The composite nanofiber membrane matrix material prepared by the conjugated electrospinning method (electrospinning combined with electrostatic spraying) solves the problems of uneven distribution of nanoparticles and particle loading, and improves the performance of liquid metal nanoparticle composite nanofiber membrane. By comparing Example 1 and Example 2 as SERS substrate effect verification, it can be concluded that the fiber membrane prepared by the conjugated electrospinning method is used as the matrix material, and the liquid metal nanoparticles are evenly distributed inside the nanofibers. Evenly distributed "hot spots" are provided between the liquid metal nanoparticles and between the particles and the fibers, so that it has good sensitivity and stability as a SERS substrate.

[0081] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane, characterized in that: The following steps are involved: Depositing a liquid metal nanoparticle suspension and a polymer solution on a collecting plate by electrostatic spraying and electrostatic spinning to prepare a matrix material; ultrasonically impregnating the matrix material to obtain the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane; The needle of the electrostatic spray is arranged vertically to the needle of the electrostatic spinning; The electrostatic spraying and the electrostatic spinning are performed simultaneously.

2. The method for preparing a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane according to claim 1, characterized in that: The method for preparing the liquid metal nanoparticle suspension comprises the following steps: The liquid metal and the stabilizer are added to a solvent for ultrasonic treatment, followed by centrifugation, and the obtained supernatant is the liquid metal nanoparticle suspension.

3. The method for preparing a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane according to claim 2, characterized in that: The liquid metal is a gallium-indium alloy; the stabilizer is at least one of polyvinyl pyrrolidone, polyoxyethylene polyoxypropylene ether F127, dodecanethiol, sodium dodecylbenzene sulfonate or N,N-dimethylacetamide.

4. The method for preparing a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane according to claim 2, characterized in that: The mass volume ratio of the liquid metal to the solvent is 1g:(15-25)mL; the solvent is one of anhydrous ethanol, acetone, and dimethylformamide; the centrifugal speed is 1000r / min-4000r / min, and the time is 0-60min.

5. The method for preparing a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane according to claim 1, characterized in that: The polymer in the polymer solution is at least one of polyvinyl alcohol, polyethylene oxide, polyimide or polyvinylidene fluoride; the solvent of the polymer solution is water; and the concentration of the polymer in the polymer solution is 5-15%.

6. The method for preparing a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane according to claim 1, characterized in that: The lateral distance between the needle of the electrostatic spray and the needle of the electrostatic spinning is 60 to 120 mm, and the height difference is 30 to 60 mm; The voltage of the electrospinning is +12kv, the injection speed is 0.4ml / h, the receiving distance is 10cm, and the time is 1h; the voltage of the electrostatic spray is -4 to -12kv, the injection speed is 0.4 to 1.2ml / h, and the time is 1h; the needle of the electrostatic spray is located between the needle of the electrospinning and the collecting plate.

7. The method for preparing a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane according to claim 1, characterized in that: The ultrasonic impregnation specifically comprises: immersing the base material in a liquid metal nanoparticle suspension for ultrasonic treatment; the power of the ultrasonic treatment is 200W to 300W, and the time is 10min to 60min.

8. A uniformly dispersed liquid metal nanoparticle composite nanofiber membrane prepared according to the preparation method according to any one of claims 1 to 7.

9. Use of the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane as claimed in claim 8 in preparing a SERS substrate.

10. A SERS substrate, characterized in that: The raw material includes the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane as described in claim 8.

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