Preparation method, product and application of a composite nanofiber membrane

Abstract

The present invention relates to the technical field of electrospinning, and particularly to a preparation method, a product and an 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 collecting plate by means of electrospray and electrospinning to prepare a matrix material; and subjecting the matrix material to ultrasonic impregnation to obtain a liquid metal nanoparticle composite nanofiber membrane with uniform dispersion. By means of the preparation method combining electrospinning and electrospray, the present invention anchors liquid metal nanoparticles on fibers, and utilizes the action of a conjugate electric field to enable the particles and the fibers to meet in the air, so that the particles can be more uniformly loaded inside the fibers. The method of ultrasonic impregnation increases the loading amount of the liquid metal nanoparticles on the surface of the liquid metal nanoparticle composite nanofiber. The two processes complement each other and promote the uniform dispersion of the liquid metal nanoparticles in the fibers.

Description

Technical Field

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

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

[0003] As a convenient and versatile technique, electrospinning has been developed for the large-scale production of ultrafine polymer nanofiber membranes embedded with plasmonic nanoparticles. Using this technique, various shape-controllable plasmonic nanoparticles with remarkable 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 cost-effective SERS substrates. However, the active materials of existing SERS substrates based on noble metals such as gold, silver, and copper generally have contradictions between sensitivity and stability (susceptible to environmental interference), limitations in the adsorption of target molecules, 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 nanoparticle distribution, difficult control of process parameters, and cumbersome operation steps, which limit the large-area preparation of substrates with good SERS signal uniformity and are difficult to scale up to large-scale conventional SERS detection. Therefore, how to develop stable, inexpensive, large-scale, and reliable SERS substrates is a technical problem that those skilled in the art are committed to solving. Summary of the Invention

[0004] Based on the above, the present invention provides a preparation method, product and application of a composite nanofiber membrane of uniformly dispersed liquid metal nanoparticles to solve the problem of uneven dispersion of metal nanoparticles during 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 preparation method of a composite nanofiber membrane of uniformly dispersed liquid metal nanoparticles, comprising the following steps:

[0007] A matrix material is prepared by depositing a suspension of liquid metal nanoparticles and a polymer solution onto a collection plate by electrospray and electrospinning respectively, and the matrix material is ultrasonically impregnated to obtain the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane;

[0008] The needle of the electrospray is perpendicularly arranged to the needle of the electrospinning;

[0009] The electrospray and the electrospinning are carried out simultaneously.

[0010] In the present invention, the fiber membrane prepared by combining electrospinning and electrospray is used as the matrix material for subsequent ultrasonic impregnation of liquid metal nanoparticles. Under the action of ultrasound, the liquid metal nanoparticles are uniformly 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 by the above preparation method.

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

[0013] The fourth technical solution of the present invention is a SERS substrate, the raw materials thereof including the above uniformly dispersed liquid metal nanoparticle composite nanofiber membrane.

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

[0015] By the preparation method of combining electrospinning and electrospray (conjugate electrospinning method), the present invention anchors liquid metal nanoparticles on fibers. By utilizing the action of the conjugate electric field (the electric field formed by electrospinning interacts with the electric field formed by electrospray), the particles and the fibers can meet in the air, so that the particles can be more uniformly loaded on the fibers to prepare the matrix material. The method of ultrasonic impregnation improves the loading amount of liquid metal nanoparticles on the surface of the liquid metal nanoparticle composite nanofiber membrane. The matrix constructed by combining electrospinning and electrospray promotes the uniform distribution of liquid metal nanoparticles inside the fibers. The two processes (conjugate electrospinning method and ultrasonic impregnation) complement each other. The SERS substrate constructed by combining the two processes has a more uniform SERS hot spot distribution, and its SERS performance is greatly enhanced due to the provision of more SERS hot spots.

[0016] By using the method of the present invention, a uniformly dispersed liquid metal nanoparticle composite nanofiber membrane can be prepared, solving the problem of non-uniform dispersion of nanoparticles during the preparation of existing multi-composite thin 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 at the same time has the characteristics of good uniformity and stability. Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

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

[0020] Figure 2 It is the electric field simulation distribution diagram of the matrix material prepared by conjugate electrospinning in Example 1 of the present invention; among them, (a) is the electric field line distribution diagram at a horizontal distance of 60 cm, (b) is the electric field line distribution diagram at a horizontal distance of 80 cm, (c) is the electric field line distribution diagram at a horizontal distance of 100 cm, and (d) is the electric potential distribution diagram at different horizontal distances (60, 80, 100 cm).

[0021] Figure 3 It is the SEM and EDS mapping diagrams of the matrix material prepared in Example 1 of the present invention.

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

[0023] Figure 5 It is the effect verification diagram of the stability and sensitivity of the SERS substrate prepared in Examples 1-4 of the present invention; among them, (a) is the SERS spectrum of R6G collected on the SERS substrates prepared in Examples 1-4, (b) is the SERS spectra of 3 different points of R6G on the E-Au@LM-PI SERS substrate, and (c) is the intensity diagram of the peaks at 614 cm -1 of the 3 SERS spectra on the E-Au@LM-PI SERS substrate. Detailed Embodiments

[0024] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0025] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0026] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice 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 related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0027] Without departing from the scope or spirit of the present invention, various improvements and modifications can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0028] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all 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] Deposit a liquid metal nanoparticle suspension and a polymer solution on a collection plate by electrospraying and electrospinning respectively to prepare a matrix material; subject the matrix material to ultrasonic impregnation to obtain the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane;

[0031] The needle of the electrospray is perpendicularly arranged to the needle of the electrospinning;

[0032] The electrospray and the electrospinning are carried out simultaneously.

[0033] The orthogonal arrangement (90°) of the needle for electrospray and the needle for electrospinning can enable more sufficient interaction between particles and fibers. The needle for electrospinning is perpendicular to the collecting plate. Such placement can make the formation of electrospun fibers more uniform and stable during the deposition process. The needle for electrospray is parallel to the collecting plate, which enables the electrosprayed particles to be more evenly dispersed in the fibers. A skewed angle will affect the non-uniformity of the electric field distribution and the stability during spraying and spinning. 60° (when the needle for electrospinning is perpendicular to the collecting plate, the included angle between the needle for electrospray and the needle for electrospinning is 60°) will greatly affect the straight jet stage during the fiber formation process, thereby affecting the stability of the jet during fiber deposition and resulting in the phenomenon of flying filaments. 120° (when the needle for electrospinning is perpendicular to the collecting plate, the included angle between the needle for electrospray and the needle for electrospinning is 120°) will affect the curing process of the fibers, thereby destroying the uniform distribution of fiber deposition and causing the fibers to adhere into bead-like shapes. Therefore, the present invention defines the orthogonal arrangement (90°) of the needle for electrospray and the needle for electrospinning.

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

[0035] Adding liquid metal and a stabilizer to a solvent for ultrasonic treatment, and then centrifuging. 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 - 3 nm) 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, thoroughly solving the problem of environmental (fluorescence) interference. In addition, gallium nanoparticles are locally confined on the surface or inside of nanofibers with high porosity, forming abundant three-dimensional SERS "hot spots"; and the large specific surface area of the self-supporting three-dimensional porous structure fibers is easy to fully contact with the analyte (providing more adsorption sites), achieving the purpose of SERS detection with stability, uniformity, and high sensitivity.

[0038] In a preferred embodiment of the present invention, the stabilizer is at least one of polyvinylpyrrolidone, polyoxyethylene polyoxypropylene ether F127, dodecanethiol, sodium dodecylbenzenesulfonate, or N,N-dimethylacetamide. In a further preferred embodiment of the present invention, the stabilizer is polyvinylpyrrolidone.

[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 the positive and negative electrodes of the power supply are connected respectively; the needle for electrospray is placed orthogonally (vertically) to the needle for electrospinning and a voltage is applied, the lateral and longitudinal distances between the two nozzles are adjusted, and electrospinning and electrospray are carried out simultaneously on the collecting plate to prepare a liquid metal nanoparticle composite nanofiber membrane with uniform dispersion.

[0046] The liquid metal nanoparticles from electrospray and the nanofibers from electrospinning meet in the air, which can ensure that the surface of the nanofiber membrane is uniformly loaded with liquid metal nanoparticles.

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

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

[0049] The present invention provides a method for preparing a liquid metal nanoparticle composite nanofiber membrane with uniform dispersion in one step. By the conjugate electrospinning method, opposite-polarity voltages are applied to the electrospray nozzle and the electrospinning nozzle, so that the electrospun fibers and the electrosprayed nanoparticles are crosslinked in the air. By adjusting the process parameters, the liquid metal nanoparticles can be uniformly loaded on the nanofiber membrane. The nanofibers serve as the matrix, which can make the liquid metal nanoparticles more evenly distributed and prevent the nanoparticles from agglomerating, thereby improving the performance of the nanoparticles. The nanoparticles modify the surface of the nanofibers and improve the performance of the nanofibers, while realizing the multifunctionality of the nanofibers and the nanoparticles. The method of ultrasonic impregnation increases the loading amount of the liquid metal nanoparticles on the surface of the liquid metal nanoparticle composite nanofiber membrane, and the matrix constructed by electrospinning combined with electrospray promotes the uniform distribution of the liquid metal nanoparticles inside the fibers. The two processes complement each other. The SERS substrate constructed by combining the two processes has a more uniform distribution of SERS hot spots, and its SERS performance is greatly enhanced due to the provision of more SERS hot spots. The liquid metal nanoparticle composite nanofiber membrane with uniform dispersion prepared by the present invention can be used as a flexible SERS substrate with antibacterial properties, uniformity and stability for the rapid detection of trace substances.

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

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

[0052] The fourth aspect of the present invention provides an SERS substrate, the raw materials of which include the above uniformly dispersed liquid metal nanoparticle composite nanofiber membrane.

[0053] In the present invention, the "room temperature" and "normal temperature", unless otherwise specified, both represent 15 - 20 °C.

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

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

[0056] The liquid metal nanoparticle suspension (LM NPs) used in the embodiments of the present invention is prepared through the following steps: Add 0.5 g of EGa75In25 into a 20 - ml sample bottle, add 10 ml of absolute ethanol and 0.05 g of polyvinylpyrrolidone (stabilizer), insert the probe of a Weiheng ultrasonic cell disruptor (model KC - 500W) into the ethanol for ultrasonic treatment, perform ultrasonic treatment at 250 W for 120 min at room temperature. To reduce the uncertainty of temperature, carefully control the water temperature: Place a thermometer in the water bath to detect temperature changes, change the water every 10 min to ensure that the water temperature is within 20 °C. After ultrasonic treatment, place the suspension in a high - speed centrifuge and centrifuge at 3000 rpm for 30 min. The large particles deposit at the bottom, and the obtained supernatant is the liquid metal nanoparticle suspension for electrospray.

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

[0058] The present invention is further illustrated by the following examples.

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

[0060] Example 1 (Preparation of a liquid metal nanoparticle composite nanofiber membrane E - Au@LM - PI by conjugate electrospinning assisted ultrasonic impregnation)

[0061] Draw 1 mL of polyimide solution and place it in a syringe with a capacity of 1 mL for electrospinning; place the liquid metal nanoparticle suspension in a syringe with a capacity of 1 mL for electrospraying; place the electrospinning needle and the electrospraying needle perpendicular to each other (the direction of the electrospinning needle is perpendicular to the collecting plate, and the direction of the electrospraying needle is parallel to the collecting plate), set the horizontal distance between the two to 100 mm, and the height difference to 30 mm. Adopt the conjugate electrospinning method, provide a voltage of +12 kV for the electrospinning needle and a voltage of -4 kV for the electrospraying needle, adjust the injection speeds of electrospinning and electrospraying respectively, set the injection speed of electrospraying to 1.2 mL / h, and the injection speed of electrospinning to 0.4 mL / h. Set the receiving distance between the electrospinning needle and the collecting plate (with aluminum foil on the collecting plate) to 10 cm. Perform electrospinning and electrospraying simultaneously for 1 h to deposit the matrix material on the collecting plate.

[0062] Immerse the matrix material in the liquid metal nanoparticle suspension for ultrasonic treatment to uniformly load the liquid metal nanoparticles on the surface of the matrix material, and dry it at room temperature to obtain a liquid metal nanoparticle composite nanofiber membrane E-Au@LM-PI with uniform dispersion as the substrate; among them, the process parameters of the ultrasonic treatment are set as: time 30 min, power 250 w. Perform gold spraying treatment on the prepared substrate to construct an E-Au@LM-PI SERS substrate.

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

[0064] Example 2 (Preparation of liquid metal nanoparticle composite nanofiber membrane Au@LM-PI by ultrasonic impregnation method)

[0065] Draw 1 mL of polyimide solution and place it in a syringe with a capacity of 1 mL for electrospinning, provide a voltage of +12 kV for the electrospinning needle, the injection speed is 0.4 mL / h, and set the receiving distance between the electrospinning needle and the collecting plate (with aluminum foil on the collecting plate) to 10 cm to deposit polyimide nanofibers on the collecting plate.

[0066] Immerse the polyimide nanofibers in the liquid metal nanoparticle suspension, and through ultrasonic treatment, uniformly load the liquid metal nanoparticles on the surface of the polyimide nanofibers, and dry it at room temperature to obtain a liquid metal nanoparticle composite nanofiber membrane Au@LM-PI as the substrate. The parameters of the ultrasonic treatment are set as: time 30 min, power 250 w. Perform gold spraying treatment on the prepared substrate to construct an Au@LM-PI SERS substrate.

[0067] Example 3 (Fiber membrane gold-plated Au-PI)

[0068] Absorb 1 mL of polyimide solution and place it in a syringe with a capacity of 1 ml for electrospinning. Provide a voltage of +12 kV to the electrospinning needle tip, with an injection speed of 0.4 ml / h. Set the receiving distance between the electrospinning needle tip and the collection plate (with aluminum foil on the collection plate) to 10 cm, and deposit polyimide nanofibers on the collection plate. Directly perform gold spraying on the electrospun polyimide nanofibers to construct an Au-PI SERS substrate.

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

[0070] Directly perform gold spraying on a clean Si wafer to construct an Au@Si SERS substrate.

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

[0072] Through simulation analysis of the electric field distribution during the electrospinning process of the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane prepared by the conjugate electrospinning method in Example 1, the mechanism of uniformly preparing the composite film by the conjugate electrospinning method is revealed. The electric field analysis is carried out using Comsol software, and the software modeling and simulation are as follows:

[0073] (1) Geometric model: By simulating and analyzing the electric field distribution during electrospinning, 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: the needle tip, the receiving device, and the shielding net. The model is simplified, a three-dimensional model is constructed, and the shielding net, electrospinning needle tip, and electrospray needle tip are set respectively. The diameter of the nozzle is 0.6 mm, the height of the nozzle is 10 mm, and the range of the shielding net is a cube with a side length of 250 mm. The height of the collection plate is 200 mm, the depth is 200 mm, and the height is 10 mm. The horizontal and vertical distances between the electrospinning nozzle and the electrospray nozzle are set to (60, 80, 100 mm) and 30 mm respectively. Finally, the horizontal distance is determined to be 100 mm

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

[0075] Table 1

[0076] Parameter Electrospinning nozzle Electrospray nozzle Collection plate Screen mesh Relative permittivity 1 1 1 1 Material Stainless steel Stainless steel Aluminum Air Boundary condition 12000V -4000V 0V Grounding

[0077] The simulation results are as Figure 2 shown, and by Figure 2The electric field distribution of the conjugate electrospinning method and the electric field interaction distribution when electrospraying is combined with electrospinning can be obtained from the simulation result diagram. From this, it can be concluded that the nanoparticles can intersect with the electrospun nanofibers in the air, ensuring that the fiber membrane is uniformly dispersed with liquid metal particles loaded thereon.

[0078] The substrate material prepared in Example 1 was analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results are as Figure 3 shown (in the figure, the electron image 25 is the SEM image, and the rest are the EDS mapping images). From Figure 3 the SEM image and the EDS spectrum, it can be determined that for the fiber membrane (substrate material) prepared by electrospinning combined with electrospraying (conjugate electrospinning method), the liquid metal nanoparticles are uniformly dispersed on the nanofibers.

[0079] The liquid metal nanoparticle composite nanofiber membrane (SERS substrate) prepared by ultrasonic impregnation in Example 2 was analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results are as Figure 4 shown (in the figure, Electron Image1 is the SEM image, and the rest are the EDS mapping images). From Figure 4 this, it can be seen that by constructing the substrate material with subsequent ultrasonic impregnation through the conjugate electrospinning method, the uniformity of the distribution and the loading amount of the liquid metal nanoparticles in the fibers are improved, which also provides more SERS hot spots, thereby enhancing its SERS performance.

[0080] Rhodamine 6G probe molecules were used to evaluate the performance such as the sensitivity and uniformity of the composite nanofiber SERS substrate. The results are as Figure 5 shown. By comparing Example 1 and Example 2, it can be seen that there are significant differences between the composite nanofiber membrane substrate materials prepared by conjugate electrospinning-assisted ultrasonic impregnation and direct ultrasonic impregnation. The composite nanofiber membrane substrate material prepared by the conjugate electrospinning method (electrospinning combined with electrospraying) solves the problems of uneven nanoparticle distribution and particle loading, and improves the performance of the liquid metal nanoparticle composite nanofiber membrane. By comparing the effects of Example 1 and Example 2 as SERS substrates, it can be concluded that for the fiber membrane prepared by the conjugate electrospinning method as the substrate material, the liquid metal nanoparticles are uniformly distributed inside the nanofibers, and uniform "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 an SERS substrate.

[0081] The above-described embodiments are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of a liquid metal nanoparticle composite nanofiber membrane with uniform dispersibility, characterized in that, It includes the following steps: Deposit a liquid metal nanoparticle suspension and a polymer solution on a collection plate by electrospraying and electrospinning to prepare a substrate material; subject the substrate material to ultrasonic impregnation to obtain the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane; The needle of the electrospray is perpendicularly arranged with respect to the needle of the electrospinning; The electrospray and the electrospinning are carried out simultaneously; The lateral distance between the needle of the electrospray and the needle of the electrospinning is 60 - 120 mm, and the height difference is 30 - 60 mm; the needle of the electrospray is located between the needle of the electrospinning and the collection plate, and the liquid metal nanoparticles of the electrospray and the nanofibers of the electrospinning converge in the air; The voltage of the electrospinning is +12 kV, the injection speed is 0.4 ml / h, the receiving distance is 10 cm, and the time is 1 h; the voltage of the electrospray is -4 to -12 kV, the injection speed is 0.4 - 1.2 ml / h, and the time is 1 h; the needle of the electrospray is located between the needle of the electrospinning and the collection plate; The ultrasonic impregnation is specifically: immerse the substrate material in the liquid metal nanoparticle suspension for ultrasonic treatment; the power of the ultrasonic treatment is 200 W - 300 W, and the time is 10 min - 60 min; The preparation method of the liquid metal nanoparticle suspension includes the following steps: Add liquid metal and a stabilizer to a solvent for ultrasonic treatment, and then centrifuge. The obtained supernatant is the liquid metal nanoparticle suspension; The liquid metal is a gallium-indium alloy; the stabilizer is at least one of polyvinylpyrrolidone, polyoxyethylene polyoxypropylene ether F127, dodecyl mercaptan, sodium dodecylbenzenesulfonate, or N,N-dimethylacetamide; The mass-volume ratio of the liquid metal to the solvent is 1 g:(15 - 25) mL; the solvent is one of anhydrous ethanol, acetone, and dimethylformamide; the rotation speed of the centrifuge is 1000 r / min - 4000 r / min, and the time is 0 - 60 min; The polymer in the polymer solution is at least one of polyvinyl alcohol, poly(ethylene oxide), polyimide, or polyvinylidene fluoride; the solvent of the polymer solution is water; the concentration of the polymer in the polymer solution is 5 - 15%.

2. A uniformly dispersed liquid metal nanoparticle composite nanofiber membrane prepared by the preparation method according to claim 1.

3. The application of the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane according to claim 2 in the preparation of a SERS substrate.

4. A SERS substrate, characterized in that, The raw material includes the uniformly dispersed liquid metal nanoparticle composite nanofiber membrane according to claim 2.

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