Method for preparing elastic three-dimensional electrode through 3D printing based on phase transition polymer

Abstract

The invention relates to a method for preparing an elastic three-dimensional electrode through 3D printing based on a phase transition polymer. The method comprises the steps that S1, conductive ink is prepared; s2, three-dimensional electrode printing; and S3, curing and preparing the elastic three-dimensional electrode. The property that the modulus of the conductive phase transition polymer is adjustable at different temperatures is utilized, and the change of the modulus is controlled through the temperature, so that the conductive phase transition polymer can print a three-dimensional structure in a low-temperature and high-modulus state, is used in a high-temperature and low-modulus state, and has a wide application prospect in the field of flexible electronic devices.

Description

Technical Field

[0001] The present invention belongs to the field of flexible electronic technology, and in particular relates to a method for preparing elastic three-dimensional electrodes by 3D printing based on phase change polymers. Background Art

[0002] Conductive polymers (CPPs) are a class of polymers with intrinsic conductivity. Due to their unique polymer properties, excellent electrical and mechanical properties, stability, and biocompatibility, they have become one of the most promising materials for diverse applications such as energy storage, flexible electronics, and bioelectronics. Despite recent advances in CPPs and their applications, the fabrication of CPP structures and devices primarily relies on conventional fabrication techniques, such as inkjet printing, screen printing, aerosol printing, electrochemical patterning, and photolithography, which present limitations and challenges. For example, these existing CPP fabrication techniques are limited to low-resolution (e.g., exceeding 100 microns), two-dimensional (e.g., low aspect ratio) patterns, or complex and costly procedures (e.g., multi-step processes involving alignment, masking, etching, and post-assembly in cleanrooms), which hinders rapid innovation and widespread application of CPPs.

[0003] Unlike these traditional methods, three-dimensional (3D) printing offers the ability to freely design in 3D space in a programmable, convenient, and flexible manner. Using conductive polymers to print three-dimensional electrodes is of great significance for flexible electronic devices, but it is still limited to two-dimensional space and layout. Typical 3D printing processes deposit a single layer at a time and are not suitable for creating complex, filamentous, and omnidirectional wiring. Three-dimensional circuits have many advantages, such as omitting the insulating layer, improving space utilization, and better adapting to complex circuits. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers.

[0005] The present invention solves the technical problem by the following technical solutions:

[0006] A method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers, characterized in that the method comprises the following steps:

[0007] S1. Evenly mix a side chain phase transition monomer, a long chain crosslinking agent, an initiator, and a conductive material to obtain a conductive ink;

[0008] S2, using a printer to print the conductive ink of S1 at low temperature to obtain a three-dimensional electrode;

[0009] S3. Initiate and solidify the three-dimensional electrode of S2 to obtain an elastic three-dimensional electrode.

[0010] Moreover, the side chain phase transition monomer is one or more of octadecyl acrylate, hexadecyl acrylate, tetradecyl acrylate, octadecyl methacrylate, hexadecyl methacrylate, tetradecyl methacrylate, and dodecyl methacrylate.

[0011] Moreover, the mass fraction of the side chain phase transition monomer in the conductive ink is less than 40%, the mass fraction of the cross-linking agent is less than 40%, and the mass fraction of the conductive material is higher than 20%.

[0012] Moreover, the long-chain crosslinking agent is one or more of CN6021, CN8888, CN9021, trimethylolpropane triacrylate, diphenylphosphine oxide, polyurethane diacyl acid, polyethylene glycol polyethylene glycol diacrylate, polypropylene glycol diacrylate, hexanediol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, and trimethylolpropane trimethacrylate.

[0013] Moreover, the conductive material is one or more of silver nanoparticles, gold nanoparticles, copper nanoparticles, silver nanowires, gold nanowires, copper nanowires, ionic liquids, graphene, carbon nanotubes, and MXene.

[0014] Moreover, the S2 specifically includes injecting the conductive ink into the syringe of the direct writing printer, fixing the printing substrate on the printing platform, lowering the temperature of the needle tube and the cold platform, adjusting the syringe nozzle so that the printing nozzle writes the conductive ink directly on the printing cold platform according to the pattern information, and obtaining a three-dimensional electrode with a preset pattern structure.

[0015] Moreover, the printing temperature of the printer is lower than the melting temperature of the ink, and the selected range is -10 to 20°C.

[0016] Furthermore, the initiator is a thermal initiator or a photoinitiator.

[0017] The advantages and beneficial effects of the present invention are:

[0018] The present invention utilizes the property of conductive phase-change polymers with adjustable modulus at different temperatures. By controlling the modulus change through temperature, it can print three-dimensional structures in a low-temperature high-modulus state and use them in a high-temperature low-modulus state. It has broad application prospects in the field of flexible electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the 3D printed elastic three-dimensional electrode based on phase change polymer of the present invention;

[0020] Figure 2 This is a graph showing the change in elastic modulus of the 3D printed elastic stereo electrode of the present invention with temperature;

[0021] Figure 3Storage and loss modulus graphs (G' and G") of different inks prepared in the present invention at 5°C;

[0022] Figure 4 This is a tensile resistance test diagram of the 3D printed elastic three-dimensional electrode of the present invention;

[0023] Figure 5 This is a real picture of the 3D printed elastic three-dimensional electrode of the present invention lighting up a small light bulb. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the scope of protection of the present invention cannot be limited thereto.

[0025] Example 1

[0026] A method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers, the innovation of which lies in the following steps:

[0027] (1) Hexadecyl acrylate and tetradecyl acrylate were mixed in a mass ratio of 98:2, the mixture of hexadecyl acrylate and tetradecyl acrylate and polypropylene glycol diacrylate were mixed in a mass ratio of 95:5, an ethanol dispersion of silver nanowires was added, 3 wt% of a photoinitiator 2,2-dimethoxy-2-phenylacetophenone was added, and the mixture was heated at 80°C with stirring for 3 h to obtain a phase transition polymer precursor liquid;

[0028] (2) Injecting the conductive ink into the syringe of the direct writing printer, fixing the printing substrate on the printing platform, lowering the needle and cold platform temperatures, and adjusting the syringe nozzle so that the printing nozzle writes the conductive ink directly on the printing cold platform according to the pattern information to obtain a three-dimensional electrode with a preset pattern structure.

[0029] (3) The conductive three-dimensional structure prepared in step 2) is UV-cured at room temperature for 20 minutes to obtain a 3D-printed elastic three-dimensional electrode based on a phase change polymer.

[0030] Example 2

[0031] A method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers, the innovation of which lies in the following steps:

[0032] (1) Octadecyl acrylate and hexadecyl acrylate were mixed in a mass ratio of 7:3, a mixture of octadecyl acrylate and tetradecyl acrylate and polyurethane diacyl acid were mixed in a mass ratio of 3:2, an ionic liquid was added, 3 wt% of a photoinitiator, diphenylphosphine oxide was added, and the mixture was heated at 80°C with stirring for 3 h to obtain a phase transition polymer precursor liquid;

[0033] (2) injecting conductive ink into the syringe of a direct writing printer, fixing the printing substrate on the printing platform, lowering the needle and cold stage temperatures, and adjusting the syringe nozzle so that the printing nozzle writes the conductive ink directly on the printing cold stage according to the pattern information to obtain a three-dimensional electrode with a preset pattern structure;

[0034] (3) The conductive three-dimensional structure prepared in step 2) is UV-cured at room temperature for 20 minutes to obtain a 3D-printed elastic three-dimensional electrode based on a phase change polymer.

[0035] Example 3

[0036] A method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers, the innovation of which lies in the following steps:

[0037] (1) Octadecyl acrylate and dodecyl methacrylate were mixed in a mass ratio of 4:3, the mixture of octadecyl acrylate and dodecyl methacrylate and CN8888 were mixed in a mass ratio of 9:1, 5 mg / mL of ethanol dispersion of gold nanoparticles were added, and the mixture was heated and stirred at 80°C for 3 h. After the mixture was cooled, 3 wt% of thermal initiator potassium persulfate was added and quickly stirred to obtain a phase transition polymer precursor liquid;

[0038] (2) injecting conductive ink into the syringe of a direct writing printer, fixing the printing substrate on the printing platform, lowering the needle and cold stage temperatures, and adjusting the syringe nozzle so that the printing nozzle writes the conductive ink directly on the printing cold stage according to the pattern information to obtain a three-dimensional electrode with a preset pattern structure;

[0039] (3) The conductive three-dimensional structure prepared in step 2) is heated and cured at 80° C. for 30 minutes to obtain a 3D printed elastic three-dimensional electrode based on a phase change polymer.

[0040] Example 4

[0041] A method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers, the innovation of which lies in the following steps:

[0042] (1) Hexadecyl methacrylate and tetradecyl methacrylate were mixed in a mass ratio of 98:2, the mixture of hexadecyl methacrylate and tetradecyl methacrylate and trimethyl propane trimethacrylate were mixed in a mass ratio of 9:1, 5 mg / mL of ethylene glycol dispersion of gold nanowires was added, 3 wt% of photoinitiator benzophenone was added, and the mixture was heated at 80°C with stirring for 3 h to obtain a phase change polymer precursor liquid;

[0043] (2) injecting conductive ink into the syringe of a direct writing printer, fixing the printing substrate on the printing platform, lowering the needle and cold stage temperatures, and adjusting the syringe nozzle so that the printing nozzle writes the conductive ink directly on the printing cold stage according to the pattern information to obtain a three-dimensional electrode with a preset pattern structure;

[0044] (3) The conductive three-dimensional structure prepared in step 2) is UV-cured at room temperature for 20 minutes to obtain a 3D-printed elastic three-dimensional electrode based on a phase change polymer.

[0045] Figure 1 This is a schematic diagram of the 3D printed elastic three-dimensional electrode prepared by the present invention. By printing at low temperature, high modulus and high viscosity, the printed three-dimensional morphology can be maintained; the three-dimensional printed structure is solidified and used at room temperature to have a low modulus and elasticity.

[0046] Figure 2 The elastic modulus of the 3D printed elastic three-dimensional electrode prepared by the present invention changes with temperature. When the temperature is below 25 degrees, it is in a semi-crystalline state with a high modulus and suitable for 3D printing. As the temperature rises above 25 degrees, the modulus drops sharply and is in an amorphous state with a low modulus and is elastic, which is in line with the expected concept.

[0047] Figure 3 Figures 2 show the storage and loss moduli (G' and G") of different inks prepared in the present invention at 5°C. A rotational rheometer was used to measure the changes in the storage and loss moduli of the different inks at 5°C. The storage modulus of the ink obtained by uniformly mixing a side-chain phase transition monomer, a long-chain crosslinker, and an initiator to remove the conductive material, and the conductive ink obtained by uniformly mixing a side-chain phase transition monomer, a long-chain crosslinker, an initiator, and a conductive material, are higher than the loss modulus at low shear rates. The ink is in a high solid state, which is beneficial for the direct writing of independent 3D structures.

[0048] Figure 4 This is a graph showing the stretch resistance of the 3D-printed elastic three-dimensional electrode produced by this invention. At 30% strain, the resistance change and initial resistance of the elastic conductor remained stable below 0.2 over 3,000 cycles. The conductive material is uniformly mixed within the long-chain crosslinker to form a conductive path. While it's hypothetical that the conductive path would break with increasing stretching, resulting in a gradual increase in resistance, the long-chain crosslinker's excellent mechanical properties prevented the conductive path from being significantly affected. Our elastic conductor maintains relatively stable conductivity even after multiple cycles.

[0049] Figure 5 This is a real picture of the 3D printed elastic three-dimensional electrode of the present invention lighting a small light bulb, and the lighting of the light bulb proves the working stability of the three-dimensional electrode.

[0050] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers, characterized in that: The steps of the method are: S1, mixing the side chain phase transition monomer, the long chain crosslinking agent, the initiator and the conductive material uniformly to obtain a conductive ink; S2, using a printer to print the conductive ink of S1 at low temperature to obtain a three-dimensional electrode; S3, initiating and curing the three-dimensional electrode of S2 to obtain an elastic three-dimensional electrode.

2. The method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers according to claim 1, characterized in that: The side chain phase transition monomer is one or more of octadecyl acrylate, hexadecyl acrylate, tetradecyl acrylate, octadecyl methacrylate, hexadecyl methacrylate, tetradecyl methacrylate, and dodecyl methacrylate.

3. The method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers according to claim 1, characterized in that: The mass fraction of the side chain phase transition monomer in the conductive ink is lower than 40%, the mass fraction of the cross-linking agent is lower than 40%, and the mass fraction of the conductive material is higher than 20%.

4. The method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers according to claim 1, characterized in that: The long-chain crosslinking agent is one or more of CN6021, CN8888, CN9021, trimethylolpropane triacrylate, diphenylphosphine oxide, polyurethane diacrylic acid, polyethylene glycol polyethylene glycol diacrylate, polypropylene glycol diacrylate, hexanediol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, and trimethylolpropane trimethacrylate.

5. The method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers according to claim 1, characterized in that: The conductive material is one or more of nanosilver particles, nanogold particles, nanocopper particles, nanosilver wires, nanogold wires, nanocopper wires, ionic liquids, graphene, carbon nanotubes, and MXene.

6. The method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers according to claim 1, characterized in that: The S2 is specifically to inject the conductive ink into the syringe of the direct writing printer, fix the printing substrate on the printing platform, lower the temperature of the needle tube and the cold platform, adjust the syringe nozzle so that the printing nozzle writes the conductive ink directly on the printing cold platform according to the pattern information, and obtain a three-dimensional electrode with a preset pattern structure.

7. The method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymers according to claim 1, characterized in that: The printing temperature of the printer is lower than the melting temperature of the ink, and the selection range is -10 to 20°C.

8. The method for preparing elastic three-dimensional electrodes based on 3D printing of phase change polymer according to claim 1, characterized in that: The initiator is a thermal initiator or a photoinitiator.

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