Electrospun polylactic acid-gallium-indium alloy adhesive material, preparation and application thereof
By using electrospinning technology and biomimetic design, polylactic acid-gallium indium alloy adhesive materials were prepared, which solved the bonding problem of flexible strain sensors in complex environments, achieved efficient and reversible adhesion and conductivity, and improved the adhesion performance and signal detection capability of the sensor.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING FORESTRY UNIV
- Filing Date
- 2023-06-06
- Publication Date
- 2026-06-23
Smart Images
Figure CN116657327B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of flexible electronic materials technology, and in particular to a polylactic acid-gallium indium alloy adhesive material based on electrospinning, its preparation and application. Background Technology
[0002] In recent years, flexible electronic materials, with their bendable and stretchable characteristics, have attracted researchers' attention due to their widespread application in fields such as health monitoring, artificial skin, and implantation. Wearable strain sensors, in particular, are helpful for early diagnosis and late-stage treatment of diseases in medical monitoring of vital signs. Their working mechanism utilizes thin fabric sensors with high mechanical tensile strength to monitor the movement or deformation of an object's surface through resistance or capacitance strain sensitivity. Flexible stretchable strain sensors are typically fabricated by combining an elastic substrate with a conductive material. The elastic substrate is generally made of elastic polymers such as polydimethylsiloxane (PDMS) or polyurethane (PU), or fabrics. The conductive layer is typically made of conductive polymers, carbon nanotubes, graphene, metal nanowires, and transition metal carbides / nitrides (Mxene). The strain sensor substrate usually lacks adhesive properties and cannot adhere to surfaces. This can lead to deviations in the strain monitored by the strain sensor, resulting in motion artifacts and fault signals. Currently, research on flexible strain sensors mainly focuses on improving sensor sensitivity and tensile strain, with less emphasis on enhancing the adhesion of flexible electronic materials and achieving effective bonding with complex surfaces.
[0003] Studies have shown that introducing adhesive materials into strain sensors and attaching them to object surfaces can effectively improve the contact state of the substrate and achieve high-performance sensing. Flexible strain sensors with adhesive properties can be designed through structural design or chemical cross-linking methods. In the prior art, CN 115346976 A discloses a passive flexible touch-sensing thin-film device and its fabrication method, but its flexible device cannot achieve reversible bonding to the surface or effective bonding in complex environments. Meanwhile, gallium-based liquid metals possess electrical conductivity, thermal conductivity, non-toxicity, and fluid properties at room temperature, and can be composited with fabric materials to form a gecko-like multi-level micro / nano layered structure, achieving excellent photothermal conversion efficiency and super-strong adhesion. However, the surface of liquid metals lacks functional groups and has low surface energy, making it difficult to bond with insulating elastic substrates. Therefore, solving the bonding problem between liquid metals and elastic substrates is of great significance for developing strain sensors with super-strong adhesion and reversible self-adhesive properties. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a polylactic acid-gallium indium alloy adhesive material based on electrospinning, its preparation, and its application. Since the catechol groups in gecko-like bristle fibers and mussel foot silk proteins can achieve ultra-high contact adhesion under complex natural environments, this invention, through biomimetic principles and electrospinning technology, develops a high-performance adhesive capable of adapting to different surface conditions, overcoming the problems of difficulty in bonding liquid metals and limited research on reversible bonding. Specifically, this is achieved through the following technologies:
[0005] In a first aspect, the present invention provides a method for preparing a polylactic acid-gallium indium alloy adhesive material based on electrospinning, comprising the following steps:
[0006] S1. After mixing chloroform, gallium-indium alloy, and nonionic surfactant, add the mixture to a zirconium oxide tank and perform high-speed ball milling reaction for 6-6.5 hours to obtain gallium-indium alloy suspension; dissolve polylactic acid, carbonylated eucommia gum, and polypropylene carbonate in a mixed solvent of chloroform and N,N-dimethylformamide to obtain polymer solution.
[0007] S2. Add the gallium indium alloy suspension droplets obtained in step S1 to the polymer solution and stir thoroughly. Then perform electrospinning to obtain polylactic acid-gallium indium alloy fabric.
[0008] S3. One side of the polylactic acid-gallium indium alloy fabric obtained in step S2 is first soaked in a tannic acid aqueous solution under dark conditions for 48-50 hours, then washed and dried, and then soaked in an iron ion-polydopamine solution for 1-1.2 hours. The other side of the polylactic acid-gallium indium alloy fabric is then soaked in a polypyrrole solution in an ice water bath for 4-4.5 hours to obtain a polylactic acid-gallium indium alloy adhesive material.
[0009] The solid-liquid mass ratio of the above-mentioned gallium-indium alloy to chloroform is 0.5-0.75 g / mL; the mass ratio of polylactic acid, carbonylated eucommia gum, and polypropylene carbonate is 10:1:1; the volume ratio of chloroform to N,N-dimethylformamide in the mixed solvent is 4:1; and the solid-liquid mass ratio of polylactic acid to the mixed solvent is 0.08-0.16 (g / mL).
[0010] Furthermore, the mass ratio of the gallium-indium alloy suspension to the polymer solution is (1-4):5.
[0011] Furthermore, the aforementioned nonionic surfactant is one or more of Tween or Span. Generally, other commercially available nonionic surfactants can also be used to prepare gallium-indium alloy suspensions, and routine substitution of nonionic surfactants will not affect the performance of gallium-indium alloy suspensions.
[0012] Furthermore, the aforementioned nonionic surfactant is Tween 80 or Span 60, and the mass ratio of the nonionic surfactant to the gallium-indium alloy is (1-4):4.
[0013] In step S3 above, the concentration of the tannic acid aqueous solution is 5-8%.
[0014] The above-mentioned iron ion-polydopamine solution is prepared as follows: FeCl3 is dissolved in buffer solution, dopamine hydrochloride is added and mixed well, then H2O2 is added, and finally the pH of the solution needs to be adjusted to pH=3.5.
[0015] Furthermore, the concentration of polydopamine in the above iron ion-polydopamine solution is 2-2.2 mg / mL.
[0016] Preferably, the buffer solution is one of Tris buffer or PB buffer, but other buffer systems commonly used in biochemical laboratories are also applicable.
[0017] The above-mentioned polypyrrole solution is prepared by dissolving pyrrole in deionized water in an ice-water bath and adding FeCl3.
[0018] Preferably, the concentration of the above-mentioned polypyrrole solution is 0.01-0.04 g / mL.
[0019] The function of gallium-indium alloy in the main raw material of this invention is as follows: gallium-indium alloy has a special photothermal response function. The photothermal conversion function is beneficial to improving the adhesion of polylactic acid-gallium-indium alloy adhesive material. This not only enables the adhesive material to have excellent photothermal conversion efficiency and thermal conductivity, but also enhances the adhesion strength of the adhesive material.
[0020] The mechanism of step S3 in this invention is as follows: First, one side of the polylactic acid-gallium indium alloy fabric is immersed in tannic acid aqueous solution and iron ion-polydopamine solution, respectively. The phenolic hydroxyl groups of tannic acid can coordinate with iron ions, providing abundant adhesive active sites. Dopamine is a natural catecholamine that mimics the catechol groups in mussel foot silk protein to achieve ultra-high contact adhesion in complex natural environments, giving the polylactic acid-gallium indium alloy fabric a multi-layered micro-nano layer. At the same time, the efficient reversible adhesion and adhesion performance of one side of the polylactic acid-gallium indium alloy fabric are achieved through the action of surface chemical bonds. Second, the other side of the polylactic acid-gallium indium alloy fabric is immersed in polypyrrole solution. Polypyrrole is conductive, giving the fabric high strain response characteristics, so that the prepared polylactic acid-gallium indium alloy adhesive material can be widely used in wearable self-adhesive strain sensors to realize real-time electrical signal detection of self-adhesive strain sensors.
[0021] Secondly, the present invention also provides a polylactic acid-gallium indium alloy adhesive material prepared by the above preparation method.
[0022] Thirdly, this invention also provides the application of the aforementioned polylactic acid-gallium indium alloy adhesive material in wearable self-adhesive strain sensors. Applying the polylactic acid-gallium indium alloy adhesive material to wearable self-adhesive strain sensors enables real-time detection of electrical signals.
[0023] Compared with the prior art, the advantages of the present invention are:
[0024] 1. This invention utilizes electrospinning and surface post-treatment techniques in dry adhesive materials to develop a polylactic acid-gallium indium alloy adhesive material with strong photothermal conversion capability, excellent thermal conductivity, and stable adhesion under various conditions. This material is then applied to wearable self-adhesive strain sensors.
[0025] 2. Based on biomimetic principles, this adhesive material achieves highly efficient and reversible adhesion through the combined action of multi-layered micro / nano layers and surface chemical bonds. The reversible adhesion strength reaches 2.7625 MPa, and the adhesion stability is excellent. It can maintain stable adhesion even in harsh environments such as humidity and acid / alkali conditions, demonstrating significant application value. Simultaneously, polypyrrole enhances the conductivity of this adhesive material, enabling it to exhibit high strain response characteristics and real-time electrical signal detection capabilities. Attached Figure Description
[0026] Figure 1 This is a scanning electron microscope image of the polylactic acid-gallium indium alloy fabric in Example 1;
[0027] Figure 2 The elemental analysis diagram of the polylactic acid-gallium indium alloy fabric in Example 1 is shown below.
[0028] Figure 3 The image shows the surface morphology of the polylactic acid-gallium indium alloy adhesive material in Example 1.
[0029] Figure 4-5 The graph shows the photothermal conversion performance of the polylactic acid-gallium indium alloy adhesive material in Example 1.
[0030] Figure 6 This is a comparison of the adhesion properties of polylactic acid-gallium indium alloy fabric and pure polylactic acid fabric in Example 1.
[0031] Figure 7 The graph shows the adhesion performance of the polylactic acid-gallium indium alloy adhesive material in Example 1 under different humidity environments.
[0032] Figure 8 This is a diagram illustrating the method for testing the bending performance of the polylactic acid-gallium indium alloy adhesive material of Example 1 in an application example;
[0033] Figure 9The graph shows the results of the bending performance test of the polylactic acid-gallium indium alloy adhesive material of Example 1 in the application example. Detailed Implementation
[0034] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0035] The types and sources of the raw materials used in the following examples are shown in Table 1 below:
[0036]
[0037]
[0038] Experimental Example 1
[0039] (1) Preparation of polylactic acid-gallium indium alloy fabric
[0040] 2 mL of chloroform, 1.5 g of gallium-indium alloy, and 1.125 g of Tween 80 were added to a ball mill jar and subjected to high-speed ball milling for 6 h to obtain a gallium-indium alloy suspension. 0.8 g of polylactic acid, 0.08 g of carbonylated eucommia gum, and 0.08 g of polypropylene carbonate were dissolved in 8 mL of chloroform and 2 mL of N,N-dimethylformamide to obtain a polymer solution. The above gallium-indium alloy suspension was dropwise mixed with the polymer solution at a mass ratio of 2:5, and electrospinning was performed. The electrospinning voltage was 20 kV, the spinning speed was 4 mL / h, and the receiver distance was 15 cm. After electrospinning, polylactic acid-gallium-indium alloy fabric was obtained.
[0041] (2) Preparation of polylactic acid-gallium indium alloy adhesive material
[0042] One side of the prepared polylactic acid-gallium indium alloy fabric was immersed in a 5% tannic acid solution in the dark for 48 hours, then washed and dried. 0.0324 g of FeCl3 solution was added to 30 mL of Tris buffer (pH = 8.5, 50 mM), along with 0.06 g of dopamine hydrochloride and 0.02 g of H2O2. The pH of the solution was adjusted to 3.5 by adding 1 M HCl dropwise, resulting in an iron ion-polydopamine solution with a polydopamine concentration of 2 mg / mL. The tannic acid-immersed side of the polylactic acid-gallium indium alloy fabric was then immersed in the iron ion-polydopamine solution for 1.2 hours, taking care to ensure that the other side of the fabric did not come into contact with the solution. Finally, 0.5 g of pyrrole was dissolved in 40 mL of deionized water in an ice-water bath, and 10 mL of 10 mM FeCl3 solution was added to obtain a polypyrrole solution. The other side of the polylactic acid-gallium indium alloy fabric was immersed in the polypyrrole solution for 4.5 h. The immersion reaction was still carried out in an ice-water bath. After the immersion reaction was completed, the polylactic acid-gallium indium alloy adhesive material was obtained.
[0043] (3) Performance Testing
[0044] The polylactic acid-gallium indium alloy fabric prepared in this example was subjected to scanning electron microscopy (SEM) testing (see the SEM operating manual for testing methods) and elemental analysis (see GB / T 17359-1998 for specific methods). The results of the SEM testing are as follows: Figure 1 As shown, the results of elemental analysis are as follows: Figure 2 As shown, from Figure 1 It can be seen that the morphology of the polylactic acid-gallium indium alloy fabric is an irregular bead-like embedded spinning fiber, proving that the gallium indium alloy was successfully combined with the polylactic acid spinning fiber. Figure 2 This further demonstrates that the gallium-indium alloy is embedded in the interior and surface of the spun fibers in a beaded structure, forming a cross-linked network within the polylactic acid-gallium-indium alloy fabric.
[0045] The polylactic acid-gallium indium alloy adhesive material prepared in this example was tested using scanning electron microscopy (the test method is described in the operating instructions for the scanning electron microscope). The test results are as follows: Figure 3 ,from Figure 3 As can be seen, the polylactic acid-gallium indium alloy adhesive material is firmly attached to the surface of the polylactic acid-gallium indium alloy fabric, and the surface roughness is unevenly distributed, which can effectively increase the contact area of the bonding surface and improve the adhesion performance.
[0046] The photothermal conversion performance of the polylactic acid-gallium indium alloy adhesive material prepared in this example was tested. Specifically, the surface of the adhesive material was subjected to solar irradiation testing using a xenon lamp. The test results are as follows: Figure 4-5As shown, this polylactic acid-gallium indium alloy adhesive material utilizes the photothermal properties of gallium indium alloy in polylactic acid-gallium indium alloy fabric to rapidly heat up after absorbing light, exhibiting excellent photothermal conversion performance. It rapidly heats up from room temperature to about 45°C within 50 seconds, with the highest temperature reaching 56.5°C within 5 minutes.
[0047] The adhesion of the polylactic acid-gallium indium alloy fabric prepared in this example to pure polylactic acid fabric was compared (see GB / T 33334-2016 for specific methods). The test results are as follows. Figure 6 As shown, analysis Figure 6 It was found that, compared with pure polylactic acid fabric, polylactic acid-gallium indium alloy fabric had a bond shear strength that was nearly 2.6 times higher (reaching 2.7625 MPa) and a peel strength that was nearly 6 times higher (reaching 290 kPa).
[0048] The polylactic acid-gallium indium alloy adhesive material prepared in this example was subjected to adhesion performance tests under different humidity environments (specific methods are described in GB / T 33334-2016). The test results are as follows: Figure 7 As shown, the adhesion of polylactic acid-gallium indium alloy adhesive material tends to decrease in humid environments, but it can still maintain an adhesion strength of 1.97 MPa in an environment with a relative humidity of 90%, showing good adhesion performance in humid environments.
[0049] Experiment Example 2
[0050] (1) Preparation of polylactic acid-gallium indium alloy fabric
[0051] 2 mL of chloroform, 1 g of gallium-indium alloy, and 1 g of Span 60 were added to a ball mill jar and subjected to high-speed ball milling for 6.5 h to obtain a gallium-indium alloy suspension. 0.8 g of polylactic acid, 0.08 g of carbonylated eucommia gum, and 0.08 g of polypropylene carbonate were dissolved in 4 mL of chloroform and 1 mL of N,N-dimethylformamide to obtain a polymer solution. The above gallium-indium alloy suspension was dropwise mixed with the polymer solution at a mass ratio of 4:5, and electrospinning was performed. The electrospinning voltage was 20 kV, the spinning speed was 4 mL / h, and the receiver distance was 15 cm. After electrospinning, polylactic acid-gallium-indium alloy fabric was obtained.
[0052] (2) Preparation of polylactic acid-gallium indium alloy adhesive material
[0053] One side of the prepared polylactic acid-gallium indium alloy fabric was immersed in an 8% tannic acid solution in the dark for 50 hours, then washed and dried. 0.0324 g of FeCl3 was dissolved in 30 mL of Tris buffer (pH = 8.5, 50 mM), and 0.066 g of dopamine hydrochloride and 0.02 g of H2O2 were added. The pH of the solution was adjusted to 3.5 by adding 1 M HCl dropwise, thus preparing an iron ion-polydopamine solution with a polydopamine concentration of 2.2 mg / mL. The side of the polylactic acid-gallium indium alloy fabric that had been immersed in tannic acid was then immersed in this solution for 1 hour. Care was taken to ensure that the other side of the polylactic acid-gallium indium alloy fabric did not come into contact with the solution. Finally, 0.5 g of pyrrole was dissolved in 2.5 mL of deionized water in an ice-water bath, and 10 mL of 10 mM FeCl3 aqueous solution was added to obtain a polypyrrole solution. The other side of the polylactic acid-gallium indium alloy fabric was immersed in the polypyrrole solution for 4 hours. The immersion reaction was still carried out in an ice-water bath. After the immersion reaction was completed, the polylactic acid-gallium indium alloy adhesive material was obtained.
[0054] Experimental Example 3
[0055] The preparation method of polylactic acid-gallium indium alloy adhesive material in this experimental example is the same as that in Experimental Example 1, the difference is that in step "(1)" there are 1g of gallium indium alloy and 4g of Tween 80, and the mass ratio of gallium indium alloy suspension droplets to polymer solution is 1:5. All other steps are the same as those in Experimental Example 1.
[0056] Application examples
[0057] The polylactic acid-gallium indium alloy adhesive material prepared in Example 1 was subjected to bending performance testing. Specifically, the polylactic acid-gallium indium alloy adhesive material was attached to the upper joint area of a finger, and the response of the flexible self-adhesive sensor during bending was tested. The testing method is as follows: Figure 8 As shown, the test results are as follows: Figure 9 As shown. From Figure 9 As can be seen, the polylactic acid-gallium indium alloy adhesive material exhibits high flexibility. During finger bending, the sensor's resistance changes significantly, clearly demonstrating the waveform pattern of finger bending detected by the sensor. Furthermore, this polylactic acid-gallium indium alloy adhesive material can be applied to different parts of the body to monitor the movement of multiple body parts. Its excellent properties make it well-suited for application in the field of wearable self-adhesive strain sensors.
[0058] The above tests and results analysis show that this invention introduces gallium indium alloy particles into polylactic acid (PLA) spun fibers via electrospinning, and then attaches a biomimetic adhesive (tannic acid aqueous solution and iron ion-polydopamine adhesive layer) and a conductive material (polypyrrole solution) to their two surfaces, respectively, to prepare a PLA-GaIn alloy adhesive material. This PLA-GaIn alloy adhesive material possesses excellent photothermal conversion performance, stable adhesion, and conductivity, and can be widely used in wearable self-adhesive strain sensors. Self-adhesive strain sensors prepared using this PLA-GaIn alloy adhesive material can achieve temperature-strain based response functionality, promoting the development of wearable electronic fabric sensors.
[0059] The above detailed embodiments describe the implementation of the present invention. Due to page limitations, the present invention only lists the test result diagrams and result analysis of the relevant materials in Example 1, but this does not mean that the present invention did not conduct tests and result analysis on Examples 2-3. High-performance polylactic acid-gallium indium alloy adhesive materials can also be prepared using the embodiments of Examples 2-3. Furthermore, the present invention is not limited to the specific details of the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
Claims
1. A method for preparing polylactic acid-gallium indium alloy adhesive material based on electrospinning, characterized in that, Includes the following steps: S1. Trichloromethane, gallium-indium alloy, and nonionic surfactant are mixed and ball-milled to obtain a gallium-indium alloy suspension; polylactic acid, carbonylated eucommia gum, and polypropylene carbonate are dissolved in a mixed solvent of trichloromethane and N,N-dimethylformamide to obtain a polymer solution. S2. Add the gallium indium alloy suspension obtained in step S1 to the polymer solution and perform electrospinning to obtain polylactic acid-gallium indium alloy fabric. S3. First, immerse one side of the polylactic acid-gallium indium alloy fabric obtained in step S2 in a tannic acid aqueous solution, clean and dry it, and then immerse it in an iron ion-polydopamine solution; immerse the other side of the polylactic acid-gallium indium alloy fabric in a polypyrrole solution to obtain a polylactic acid-gallium indium alloy adhesive material.
2. The method for preparing polylactic acid-gallium indium alloy adhesive material based on electrospinning according to claim 1, characterized in that, In step S1, the solid-liquid mass ratio of the gallium-indium alloy to chloroform is 0.5-0.75; the mass ratio of the nonionic surfactant to the gallium-indium alloy is (1-4):4; the mass ratio of polylactic acid, carbonylated eucommia gum, and polypropylene carbonate is 10:1:1; the volume ratio of chloroform to N,N-dimethylformamide in the mixed solvent is 4:1; and the solid-liquid mass ratio of polylactic acid to the mixed solvent is 0.08-0.
16.
3. The method for preparing polylactic acid-gallium indium alloy adhesive material based on electrospinning according to claim 2, characterized in that, In step S2, the mass ratio of the gallium-indium alloy suspension to the polymer solution is (1-4):
5.
4. The method for preparing polylactic acid-gallium indium alloy adhesive material based on electrospinning according to claim 1, characterized in that, In step S3, the iron ion-polydopamine solution is prepared by dissolving FeCl3 in a buffer solution, adding dopamine hydrochloride and mixing well, and then adding H2O2.
5. The method for preparing polylactic acid-gallium indium alloy adhesive material based on electrospinning according to claim 4, characterized in that, The concentration of polydopamine in the iron ion-polydopamine solution is 2-2.2 mg / mL.
6. The method for preparing polylactic acid-gallium indium alloy adhesive material based on electrospinning according to claim 1, characterized in that, In step S3, the polypyrrole solution is prepared by dissolving pyrrole in deionized water in an ice-water bath and adding FeCl3.
7. The method for preparing polylactic acid-gallium indium alloy adhesive material based on electrospinning according to claim 6, characterized in that, The concentration of the polypyrrole solution is 0.01-0.04 g / mL.
8. The method for preparing polylactic acid-gallium indium alloy adhesive material based on electrospinning according to claim 1, characterized in that, In step S3, the concentration of the tannic acid aqueous solution is 5-8%.
9. A polylactic acid-gallium indium alloy adhesive material prepared by the preparation method according to any one of claims 1-8.
10. The application of the polylactic acid-gallium indium alloy adhesive material as described in claim 9 in a wearable self-adhesive strain sensor.