Method for preparing friction nano-generator by using photocuring 3D printing isotropic high-toughness polyurethane elastomer

Abstract

The invention provides a preparation method of a photocuring 3D printing isotropic high-toughness polyurethane elastomer for a friction nano generator, and a composition for preparing the photocuring 3D printing isotropic high-toughness polyurethane elastomer comprises the following components in parts by mass: 100 parts of a polyurethane methacrylate terminated oligomer, 0.1-0.3 part of a catalyst, 0.1-10 parts of a photoinitiator, 0.1-10 parts of a photoinitiator, 0.1-10 parts of a photoinitiator, 0.1-10 parts of a photoinitiator and 0.1-10 parts of a photoinitiator. 1-20 parts of an amine chain extender and 0-20 parts of a rheological modifier, namely gaseous silicon. The high-toughness polyurethane urea elastomer is prepared through UV-DIW printing while a solvent or a diluent is not used, an isotropic structure is achieved, the elastomer can adapt to dynamic loads and complex environments, the mechanical properties of the printed polyurethane elastomer in all directions are more uniform, and the mechanical properties of the elastomer are more uniform. And the reliability and the performance consistency in practical application are enhanced.

Description

Technical Field

[0001] The present invention relates to a method for preparing an ultraviolet-cured 3D-printed isotropic high-toughness polyurethane elastomer for use in a friction nanogenerator, and belongs to the technical field of polymer materials. Background Art

[0002] As an emerging technology that efficiently converts mechanical energy into electrical energy, triboelectric nanogenerators (TENGs) have shown great potential for applications in self-powered sensing systems, wearable electronics, and energy harvesting due to their numerous advantages, including high output power and conversion efficiency, ease of fabrication, low cost, a wide range of materials, and environmental friendliness. To further expand the application range of TENGs and enhance their performance, the development of high-performance functional materials and innovative fabrication processes has become a research hotspot and a key challenge in this field.

[0003] An elastomer is a cross-linked polymer network that can be significantly stretched or twisted and quickly return to its original state after the removal of external force. Due to its combined flexibility and elasticity, it plays an irreplaceable role in many traditional fields such as automobiles, construction, and consumer products. Polyurethane elastomer (PUE) has been widely used in wearable sensors, smart skin, and soft robotics due to its unique chemical structure and excellent physical properties, such as high elasticity, good wear resistance, outstanding mechanical strength, and adjustable hardness. In the preparation of TENG, the choice of friction layer material has a decisive influence on the device's output performance, durability, and flexible adaptability. Traditional TENG friction layer materials often have problems such as poor mechanical durability and low deformation adaptability. PUE, as a friction layer material, has significant advantages in the structural design of TENG.

[0004] Traditional molding methods, such as casting and screen printing, suffer from low precision and a lack of customization, which to some extent limits the development of PUE in TENGs. 3D printing, also known as additive manufacturing, is an emerging material molding and processing technology. It uses computer-aided design to create virtual objects and digitally slices them to construct solid shapes layer by layer. This technology offers significant advantages in fabricating geometrically complex or customized products. With the development of additive manufacturing, direct ink writing (DIW), a high-precision and efficient 3D printing technology, has become increasingly important in the fabrication of complex structures made of elastomeric materials due to its wide range of applications and high design freedom. Ultraviolet-assisted direct ink writing (UV-DIW), through its unique curing method and ink design, is well-suited to elastomeric materials, enabling room-temperature 3D printing and providing a new solution for the additive manufacturing of flexible materials. However, UV-DIW-printed PUE still faces the challenge of poor mechanical properties. To meet the critical 3D printing requirements of material flowability and curing speed, the limited ink selection results in PUE with lower tensile strength and elongation at break than those produced using traditional molding methods. On the other hand, the layer-by-layer stacking method of 3D printing results in the interlayer bonding force being weaker than the molecular chain bonding force within the material, and the strength and toughness perpendicular to the printing direction are significantly lower than those in the parallel direction.

[0005] The integrated encapsulation layer can better protect the electrodes from environmental corrosion, extending the lifespan of the TENG. Current TENG fabrication and encapsulation processes primarily rely on interfacial self-healing and self-encapsulation mechanisms, which often require the introduction of specific self-healing groups into the material structure. Wang et al. prepared a bio-based polyurethane triboelectric elastomer (BPUxPy) with self-healing, degradable, and reprocessable properties (see references: Wang, H.; Zhang, L.; Yang, W.; Xu, P.; Niu, D.; Chen, C.; Ma, P.; Ma, P. Chemical Engineering Journal 2025, 512, 162533). By adjusting the disulfide bond content and polycaprolactone content, they achieved optimal mechanical properties of 1.4 MPa and 1050%, respectively. They also fabricated a TENG to construct a wildlife monitoring system. Jia et al. prepared a fluorinated phenolic polyurethane elastomer (FPPU), whose unique electron-withdrawing effect imparts high mechanical strength. Furthermore, the resulting stretchable conductive composite material has broad application prospects in the development of flexible and smart electronic devices. (See reference: Jia, Y.; Guan, Q.; Chu, C.; Zhang, L.; Neisiany, RE; Gu, S.; Sun, J.; You, Z. Science Bulletin 2024, 69 (12), 1875-1886.) Although self-healing groups can effectively improve the interface stability and encapsulation efficiency of devices, their introduction is also accompanied by several potential defects. For example, the degradation of the mechanical properties of the matrix material limits the application of TENG in high-load scenarios to a certain extent. In addition, the introduction of such chemically unstable groups not only shortens the service life of TENG, but also may cause the risk of failure of the encapsulation interface during long-term use. In addition, Lee et al. prepared and encapsulated a transparent and stretchable single-electrode polydimethylsiloxane polyurethane-based TENG (PP-TENG) by selective photopolymerization for detecting human motion. (See reference: Lee, HJ; Kim, H.; Kim, TS; Kim, HY; Mun, J.; Choi, G.; Jeong, HE; ​​Yeo, J. Nano Energy 2024,121, 109274.) In summary, the development of high-performance polyurethane elastomers is of great significance for improving the performance of TENG and expanding its application fields. Summary of the Invention

[0006] Purpose of the invention: In order to overcome the shortcomings of the prior art, the present invention provides a method for preparing a light-cured 3D-printed isotropic high-toughness polyurethane elastomer for use in a friction nanogenerator. Without using solvents or diluents, a high-toughness polyurethane urea elastomer is prepared by UV-DIW printing, achieving an isotropic structure that can adapt to dynamic loads and complex environments, making the printed polyurethane elastomer more uniform in mechanical properties in all directions, and enhancing its reliability and performance consistency in practical applications.

[0007] The first object of the present invention is to provide a light-cured 3D-printed isotropic high-toughness polyurethane elastomer. The composition of the isotropic high-toughness polyurethane elastomer includes, by weight, 100 parts of a polyurethane methacrylate end-capped oligomer and the following components in weight: 0.1-10 parts of a photoinitiator, 1-20 parts of an amine chain extender, and 0.1-20 parts of a rheology modifier. The method for preparing a polyurethane methacrylate-terminated oligomer comprises the following steps: using polyether diol and isocyanate as raw materials, an amine (meth)acrylate monomer as a blocking agent, and adding a catalyst to synthesize the polyurethane methacrylate-terminated oligomer. The molar ratio of the polyether diol, isocyanate, amine (meth)acrylate monomer, and catalyst is 1:1-2:1-2:0.001-0.05, and exemplarily 1:2:2:0.006.

[0008] According to an embodiment of the present invention, the polyether diol includes at least one of polypropylene glycol PPG, polyethylene glycol PEG or polytetramethylene glycol PTMEG, and the molecular weight of the polyether diol is independently 1000-4000.

[0009] According to an embodiment of the present invention, the isocyanate includes at least one of toluene diisocyanate TDI, isophorone diisocyanate IPDI, diphenylmethane diisocyanate MDI, dicyclohexylmethane diisocyanate HMDI or hexamethylene diisocyanate HDI.

[0010] According to an embodiment of the present invention, the amine (meth)acrylate monomer blocking agent includes at least one of tert-butylaminoethyl methacrylate TBAEMA, tert-amylaminoethyl methacrylate TPAEMA, tert-hexylaminoethyl methacrylate THAEMA or tert-butylaminopropyl methacrylate TBAPMA and acrylate analogs thereof.

[0011] According to an embodiment of the present invention, the catalyst includes a tin catalyst, and the tin catalyst includes at least one of stannous octoate DBTO, dibutyltin octoate DBTD, or dibutyltin dilaurate DBDTL.

[0012] According to an embodiment of the present invention, the reaction temperature is 40-80°C, exemplified by 50°C, 60°C, and 70°C.

[0013] According to an embodiment of the present invention, the reaction time is 1-8 h, for example, 3 to 6 h, exemplified by 3 h, 4 h, 5 h, and 6 h.

[0014] According to an embodiment of the present invention, the reaction process of the polyurethane methacrylate terminated oligomer is as follows: Among them, HO-R1-OH represents polyether diols such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol, and OCN-R2-NCO represents diisocyanates such as isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate. H2C=C (CH3) CO2-R3-NH-R4 represents an amine (meth)acrylate such as tert-butylaminoethyl methacrylate, tert-amylaminoethyl methacrylate, tert-hexylaminoethyl methacrylate or tert-butylaminopropyl methacrylate, wherein R3 represents -(CH2)2- / -(CH2)3-, and R4 represents -C (CH3)3 / -C (CH3)2CH2CH3 / -C (CH3)2CH2CH2CH3.

[0015] According to an embodiment of the present invention, the photoinitiator includes at least one of 1-hydroxycyclohexylphenyl ketone HCPK, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide TPO, 2,4,6-trimethylbenzoyl-ethoxy-phenylphosphine oxide TPO-L, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide BAPO, 2,2-dimethoxy-1,2-diphenylethanone BDK, 2-ethyloctyl-4-dimethylaminobenzoate EDB or 4-p-toluene-2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone ITX.

[0016] According to an embodiment of the present invention, the amine chain extender includes at least one of ethylenediamine EDA, 1,4-butanediamine BDA, hexamethylenediamine HMDA, isophoronediamine IPDA, 1,3-diaminocyclohexane PACM or diphenylmethanediamine MDA.

[0017] According to an embodiment of the present invention, the rheology modifier comprises fumed silica SiO2.

[0018] According to an embodiment of the present invention, the light-cured 3D-printed isotropic high-toughness polyurethane elastomer has a breaking strength of 5.3 MPa, an elongation at break of 1640%, and an anisotropy of <5%.

[0019] The second object of the present invention is to propose a method for preparing a light-cured 3D printed isotropic high-toughness polyurethane elastomer as described above, comprising the following steps: mixing a polyurethane methacrylate end-capped oligomer, a photoinitiator, a gas silicon and an amine chain extender to obtain a polyurethane acrylate 3D printing resin composition, and then heat treating it to obtain an isotropic high-toughness polyurethane elastomer.

[0020] According to an embodiment of the present invention, the heat treatment temperature is 90-150°C, for example 100-150°C, exemplified by 100°C, 120°C, and 150°C.

[0021] According to an embodiment of the present invention, the network reconstruction principle during the heat treatment process is shown in the following reaction formula: Here, R / R' is determined by the original polymer network, and H2N-R"-NH2 represents diamines such as 4,4'-methylenebis(cyclohexylamine), 1,3-diaminocyclohexane, ethylenediamine, 1,4-butanediamine, isophoronediamine, and diphenylmethanediamine.

[0022] The third object of the present invention is to provide a friction nanogenerator prepared using any of the above-described photocurable 3D printed isotropic high-toughness polyurethane elastomers.

[0023] The fourth object of the present invention is to propose a method for preparing and encapsulating a friction nanogenerator, using a light-cured 3D-printed isotropic high-toughness polyurethane elastomer as described above to respectively prepare the substrate, friction electric layer and electrode layer of the friction nanogenerator, stack the friction electric layer, electrode layer, wire and substrate from top to bottom, and place them in an oven for interlayer welding heat treatment to achieve encapsulation preparation.

[0024] According to an embodiment of the present invention, the interlayer welding heat treatment time is 1 to 8 hours, such as 2 to 8 hours, exemplified by 2 hours, 4 hours, 6 hours or 8 hours.

[0025] The present invention also provides a method for preparing the isotropic high-toughness polyurethane elastomer 3D printing composition, comprising the following steps: (1) Using polyether diol and isocyanate as raw materials and amine (meth)acrylate monomer as blocking agent, a catalyst is added to synthesize polyurethane methacrylate end-capped oligomer; (2) mixing a polyurethane methacrylate end-capped oligomer, a photoinitiator, a gaseous silicon and an amine chain extender to obtain a polyurethane acrylate 3D printing resin composition; (3) The polyurethane acrylate 3D printing resin composition is further heat treated to obtain an isotropic and highly tough polyurethane elastomer.

[0026] The present invention further provides the resin composition and the application of the resin obtained by the preparation method in TENG.

[0027] Beneficial effects: Compared with the existing technology, this invention has the following advantages: The present invention prepares a high-toughness polyurethane urea elastomer by UV-DIW printing without using solvents or diluents, and can adapt to dynamic loads and complex environments.

[0028] The present invention realizes an isotropic structure, which makes the mechanical properties of the printed polyurethane elastomer more uniform in all directions, and enhances its reliability and performance consistency in practical applications.

[0029] This invention can accommodate a variety of polyurethane materials and other functional ink combinations, allowing for flexible adjustment of material properties (such as hardness, elasticity, and toughness) based on specific application requirements. This highly adaptable material system offers broad potential for application in diverse fields, such as healthcare, automotive, and electronics.

[0030] The present invention realizes flexible multi-material composite, integrating materials with different functions (such as rigidity, flexibility, conductivity, insulation, etc.) into the same product to meet different performance requirements in different areas.

[0031] The present invention prepares a flexible TENG by integrated printing and applies it to driving electronic devices and human body sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the infrared spectrum of the preparation of the polyurethane methacrylate-terminated oligomer in Example 1 and Example 2; Figure 2 This is a rheological test in oscillation mode using the ink in Example 1; Figure 3 The tensile curves of the polyurethane elastomers prepared in Example 1 and Example 2; Figure 4 The Photo-DSC curves of the inks in Examples 1 and 2 are as follows; Figure 5 、 6 is the anisotropy of the tensile properties of the polyurethane elastomer in Example 1, specifically the breaking strength and elongation at break; Figure 7 The scanning electron microscope images of the printed sample before and after heat treatment in Example 1; Figure 8 The polyurethane elastomer 3D printing model provided in Example 1 of the present invention; Figure 9 Schematic diagram of the bending of the flexible TENG prepared in Example 1 of the present invention; Figure 10 This is the electrical output diagram of the flexible TENG provided in Example 1 of the present invention during 1600 cycles of contact-separation process; Figure 11 The flexible TENG prepared in Example 1 of the present invention is used to drive small electronic devices; Figure 12 The flexible TENG prepared in Example 1 of the present invention is used for human body sensing. DETAILED DESCRIPTION

[0033] The integrated encapsulation layer can better protect the electrodes from external environmental corrosion and extend the service life of TENG. The current preparation and encapsulation process of TENG mainly relies on interface self-repair and autonomous encapsulation mechanisms. This process often requires the introduction of specific self-repairing groups into the material structure. To this end, the present invention proposes a polyurethane methacrylate end-capped oligomer, which is used as a 3D printing composition for preparing an isotropic high-toughness polyurethane elastomer, and is used to prepare a friction nanogenerator. The specific preparation method includes the following steps: (1) Using polyether diol and isocyanate as raw materials and amine (meth)acrylate monomer as blocking agent, a catalyst is added to synthesize polyurethane methacrylate end-capped oligomer; (2) mixing a polyurethane methacrylate end-capped oligomer, a photoinitiator, a gas silicon and an amine chain extender to obtain a polyurethane acrylate 3D printing resin composition; (3) The polyurethane acrylate 3D printing resin composition is further heat-treated to obtain an isotropic and highly tough polyurethane elastomer.

[0034] Optionally, in some examples, the molar ratio of the polyether diol, isocyanate, amine (meth)acrylate monomer and catalyst in step (1) is 1:1~2:1~2:0.001~0.05, and exemplarily is 1:2:2:0.006.

[0035] Optionally, in some examples, the temperature of the reaction in step (1) is 40-80°C, exemplified by 50°C, 60°C, and 70°C.

[0036] Optionally, in some examples, the reaction time of step (1) is 1-8 h, for example, 3-6 h, exemplified by 3 h, 4 h, 5 h, and 6 h; Optionally, in some examples, the mass ratio of the catalyst in step (1) is 0.01 to 0.5, and 0.004 is an example; Optionally, in some examples, the mass ratio of the polyurethane methacrylate end-capped oligomer, the photoinitiator, the gas silicon and the amine chain extender in step (2) is 100: (0.1-10): (0-20): (1-20); Optionally, in some examples, the heat treatment temperature in step (3) is 90-150°C, for example, 100-150°C, exemplified by 100°C, 120°C, and 150°C.

[0037] The present invention further provides the resin composition and the application of the resin obtained by the preparation method in TENG.

[0038] On the other hand, the present invention also provides a method for preparing and packaging a high-performance TENG, using the isotropic high-toughness polyurethane elastomer to prepare the substrate, triboelectric layer and electrode layer of the TENG respectively, and stacking the triboelectric layer, electrode layer, wire and substrate from top to bottom and placing them in an oven for heat treatment to achieve packaging preparation.

[0039] Optionally, in some examples, the heat treatment temperature is 90-150°C, for example, 100-150°C, exemplified by 100°C, 120°C, and 150°C.

[0040] Optionally, in some examples, the interlayer welding heat treatment time is 1 to 8 hours, for example, 2 to 8 hours, exemplified by 2 hours, 4 hours, 6 hours, and 8 hours.

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] Example The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0043] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0044] Example 1 (1) Synthesis of polyurethane methacrylate terminated oligomers: A prepolymer was prepared by mixing polypropylene glycol (Mn = 2000 g / mol, 100 g, 0.05 mol), isophorone diisocyanate (22.23 g, 0.1 mol) and catalyst dibutyltin dilaurate (0.18 g, 0.0003 mol) and reacting them at 50 °C for 3 hours until the isocyanate group content stabilized.

[0045] 2-(tert-Butylamino)ethyl methacrylate TBAEMA (18.25 g, 0.1 mol) was reacted with the prepolymer and stirred at 50°C for 3 hours until the isocyanate groups reacted completely to obtain a polyurethane methacrylate-terminated oligomer.

[0046] (2) Preparation of printing ink The polyurethane methacrylate-terminated oligomer (100 g), the photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (1 g), and 4,4′-methylenebis(cyclohexylamine) (6 g) were added and mixed in appropriate proportions. To adjust the rheological and mechanical properties of the ink, fumed silica (SiO2, 20 nm particle size, 5 g) was added to the mixture to optimize the ink's viscosity and printing performance. The mixture was dispersed in a high-speed disperser at 3000 rpm for 3 minutes to ensure thorough dispersion and the removal of air bubbles, resulting in a uniform ink suitable for UV-DIW printing.

[0047] (3) UV direct writing printing and thermal curing Printing was performed under UV light (365 nm wavelength, 30 mW / cm² intensity) for real-time curing. The nozzle diameter was 0.6 mm, and the air pressure was 500 kPa. The UV power and exposure time were controlled to ensure complete ink curing and high-precision printed structures. The printed polyurethane elastomer material was then thermally cured at 120°C for 2 hours to convert it into a polyurethaneurea elastomer. This thermal curing process further improved the material's mechanical properties, enhancing its toughness and also improving its anisotropy.

[0048] (4) Preparation of TENG Polyurethane methacrylate oligomer, photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 4,4'-methylenebiscyclohexylamine and fumed silica were mixed to prepare the triboelectric layer and substrate of TENG. Polyurethane methacrylate oligomer, photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 4,4'-methylenebiscyclohexylamine and multi-walled carbon nanotubes (CNTs, length: 10-20 μm) were mixed to prepare the electrode layer of TENG. The prepared ink was formed by UV-DIW printing and then heat-treated and encapsulated in step (3).

[0049] See attached Figure 1 , which is the preparation infrared spectrum of the polyurethane methacrylate terminated oligomer provided in Examples 1 and 2 of the present invention, 3300 cm -1 1N-H stretching vibration and 1660cm -1 , 810cm -1The bending vibration of C=C and =CH appears at 2270cm -1 The NCO characteristic peak gradually weakened until it disappeared.

[0050] See attached Figure 2 , which is a graph showing the shear modulus variation of the printing ink provided in Example 1 of the present invention. As can be seen from the graph, under low shear stress, the printing ink is in the linear viscoelastic region, with the storage modulus greater than the loss modulus. However, under high shear stress, the storage modulus is less than the loss modulus, indicating that the ink can be extruded smoothly under high shear stress and retains its shape when shearing ceases. Therefore, the printing ink meets the required shear-thinning properties for successful printing.

[0051] See attached Figure 3 , which shows the UV-curing photo-DSC curves of the printing inks provided in Examples 1 and 2 of the present invention. As can be seen from the figure, under UV irradiation, the printing inks rapidly undergo a curing reaction, reaching a peak value within approximately 1 second. This allows for real-time curing of the inks, resulting in samples with excellent printing accuracy.

[0052] See attached Figure 4 , which is the tensile curve of the polyurethane urea elastomer provided by Example 1 and Example 2 of the present invention. It can be seen from the figure that the prepared polyurethane urea elastomer has a breaking strength of 5.3 MPa, an elongation at break of 1640% and 8 MPa, 320%, respectively, and has high toughness.

[0053] See attached Figure 5 , 6, which is the tensile property anisotropy of the polyurethane elastomer provided in Example 1 of the present invention. The anisotropy of the printed material is calculated according to the following formula: The anisotropy was significantly reduced from 56% to 4%, and this isotropy was attributed to the deblocking of the thermally cured isocyanate and the chain extension reaction of the diprimary amine, resulting in interlayer bonding and intralayer bonding.

[0054] See attached Figure 7 , which is a scanning electron microscope image of the printed sample provided in Example 1 of the present invention before and after heat treatment. It can be seen that the original clear interface between the layers becomes blurred after heat treatment, indicating that new interlayer bonding is generated by chain extension through heat treatment, and the force at the interface is improved.

[0055] See attached Figure 8 , which is the 3D printing model provided by Example 1 of the present invention, and it can be seen that it has high precision.

[0056] See attached Figure 9, which is the flexible TENG provided in Example 1 of the present invention, can be bent to a large extent, indicating the potential of the prepared flexible TENG for application in human motion sensing.

[0057] See attached Figure 10 , which is the flexible TENG provided in Example 1 of the present invention, maintains continuous and stable output during 1600 cycles of contact-separation process, that is, the prepared flexible TENG has stability and long-term reliability.

[0058] See attached Figure 11 , it is that the flexible TENG provided in Example 1 of the present invention can be used as a reliable energy source for small electronic devices, and is used to drive small electronic devices such as thermometers and hygrometers after multiple contact and separation.

[0059] See attached Figure 12 , it is the flexible TENG provided in Example 1 of the present invention that is used for human body sensing, monitoring elbow bending, etc.

[0060] Example 2 The difference from Example 1 is that the molecular weight of the polypropylene glycol in step (1) is different, and the amounts of isophorone diisocyanate and 2-(tert-butylamino)ethyl methacrylate are different.

[0061] (1) Synthesis of polyurethane methacrylate terminated oligomers: A prepolymer was prepared by mixing polypropylene glycol (Mn = 1000 g / mol, 100 g, 0.1 mol), isophorone diisocyanate (44.58 g, 0.2 mol) and catalyst dibutyltin dilaurate (0.38 g, 0.0006 mol) in a ratio of 2:2 and reacting at 50 °C for 3 h until the isocyanate group content stabilized.

[0062] 2-(tert-Butylamino)ethyl methacrylate TBAEMA (36.5 g, 0.2 mol) was reacted with the prepolymer and stirred at 50°C for 3 hours until the isocyanate groups reacted completely to obtain a polyurethane methacrylate-terminated oligomer.

[0063] (2) Preparation of printing ink The oligomer (100 g), the photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (1 g), and 4,4′-methylenebis(cyclohexylamine) (6 g) were added and mixed in appropriate proportions. To adjust the rheological and mechanical properties of the ink, fumed silica (SiO2, 20 nm particle size, 5 g) was added to the mixture to optimize the ink's viscosity and printing performance. The mixture was dispersed in a high-speed disperser at 3000 rpm for 3 minutes to ensure full dispersion and the removal of air bubbles, resulting in a uniform ink suitable for UV-DIW printing.

[0064] (3) UV direct writing printing and thermal curing Printing was performed under UV light (365 nm wavelength, 30 mW / cm² intensity) for real-time curing. The nozzle diameter was 0.6 mm, and the air pressure was 500 kPa. The UV power and exposure time were controlled to ensure complete ink curing and high-precision printed structures. The printed polyurethane elastomer material was then thermally cured at 120°C for 2 hours to convert it into a polyurethaneurea elastomer. This thermal curing process further improved the material's mechanical properties, enhancing its toughness and also improving its anisotropy.

[0065] Example 3 Except for step (3), the steps are the same as those in Example 1. The difference from Example 1 is that the duration of thermal curing is 4 hours.

[0066] Printing was performed under UV light (365 nm wavelength, 30 mW / cm² intensity) for real-time curing. The nozzle diameter was 0.6 mm, and the air pressure was 500 kPa. The UV power and exposure time were controlled to ensure complete curing of the ink and high precision of the printed structure. The printed polyurethane elastomer material was then thermally cured at 120°C for four hours to convert it into a polyurethaneurea elastomer. This thermal curing process further improved the material's mechanical properties, enhancing its toughness and also improving its anisotropy.

[0067] Example 4 Except for step (3), the steps are the same as those in Example 1. The difference from Example 1 is that the duration of thermal curing is 6 hours.

[0068] Printing was performed under UV light (365 nm wavelength, 30 mW / cm² intensity) for real-time curing. The nozzle diameter was 0.6 mm, and the air pressure was 500 kPa. UV power and exposure time were controlled to ensure complete ink curing and high-precision printed structures. The printed polyurethane elastomer material was then thermally cured at 120°C for 6 hours to convert it into a polyurethaneurea elastomer. This thermal curing process further improved the material's mechanical properties, enhancing its toughness and also improving its anisotropy.

[0069] Example 5 Except for step (3), the same steps are performed as in Example 1. The difference from Example 1 is that the duration of thermal curing is 8 hours.

[0070] Printing was performed under UV light (365 nm wavelength, 30 mW / cm² intensity) for real-time curing. The nozzle diameter was 0.6 mm, and the air pressure was 500 kPa. UV power and exposure time were controlled to ensure complete ink curing and high-precision printed structures. The printed polyurethane elastomer material was then thermally cured at 120°C for 8 hours to convert it into a polyurethaneurea elastomer. This thermal curing process further improved the material's mechanical properties, enhancing its toughness and also improving its anisotropy.

[0071] Example 6 Except for step (3), the steps are the same as those in Example 1. The difference from Example 1 is that the thermal curing temperature is 100°C.

[0072] Printing was performed under UV light (365 nm wavelength, 30 mW / cm² intensity) for real-time curing. The nozzle diameter was 0.6 mm, and the air pressure was 500 kPa. UV power and exposure time were controlled to ensure complete ink curing and high-precision printed structures. The printed polyurethane elastomer material was then thermally cured at 100°C for 2 hours to convert it into a polyurethaneurea elastomer. This thermal curing process further improved the material's mechanical properties, enhancing its toughness and also improving its anisotropy.

[0073] Example 7 Except for step (3), the steps are the same as those in Example 1. The difference from Example 1 is that the thermal curing temperature is 100° C. and the duration is 4 hours.

[0074] Printing was performed under UV light (365 nm wavelength, 30 mW / cm² intensity) for real-time curing. The nozzle diameter was 0.6 mm, and the air pressure was 500 kPa. The UV power and exposure time were controlled to ensure complete curing of the ink and high precision of the printed structure. The printed polyurethane elastomer material was then thermally cured at 100°C for 4 hours to convert it into a polyurethaneurea elastomer. This thermal curing process further improved the material's mechanical properties, enhancing its toughness and also improving its anisotropy.

[0075] Example 8 Except for step (3), the steps are the same as those in Example 1. The difference from Example 1 is that the thermal curing temperature is 100° C. and the duration is 6 hours.

[0076] Printing was performed under UV light (365 nm wavelength, 30 mW / cm² intensity) for real-time curing. The nozzle diameter was 0.6 mm, and the air pressure was 500 kPa. The UV power and exposure time were controlled to ensure complete curing of the ink and high precision of the printed structure. The printed polyurethane elastomer material was then thermally cured at 100°C for 6 hours to convert it into a polyurethaneurea elastomer. This thermal curing process further improved the material's mechanical properties, enhancing its toughness and also improving its anisotropy.

[0077] Example 9 Except for step (3), the steps are the same as those in Example 1. The difference from Example 1 is that the thermal curing temperature is 100° C. and the duration is 8 hours.

[0078] Printing was performed under UV light (365 nm wavelength, 30 mW / cm² intensity) for real-time curing. The nozzle diameter was 0.6 mm, and the air pressure was 500 kPa. UV power and exposure time were controlled to ensure complete ink curing and high-precision printed structures. The printed polyurethane elastomer material was then thermally cured at 100°C for 8 hours to convert it into a polyurethaneurea elastomer. This thermal curing process further improved the material's mechanical properties, enhancing its toughness and also improving its anisotropy.

[0079] Example 10 Except for step (2), the same procedures as in Example 1 are carried out, except that the amount of 4,4′-methylenebis(cyclohexylamine) used is 0.2 g.

[0080] The oligomer (10 g), photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (0.1 g), and 4,4′-methylenebis(cyclohexylamine) (0.2 g) were added and mixed in proportion. To adjust the rheological and mechanical properties of the ink, fumed silica (SiO2, particle size 20 nm, 0.5 g) was added to the mixture to optimize the ink's viscosity and printing performance. The mixture was dispersed in a high-speed disperser at 3000 rpm for 3 minutes to ensure that the material was fully dispersed and bubbles were removed, resulting in a uniform printing ink suitable for UV-DIW printing.

[0081] Example 11 Except for step (2), the same procedures as in Example 1 are carried out, except that the amount of 4,4′-methylenebis(cyclohexylamine) used is 0.4 g.

[0082] The oligomer (10g), the photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (0.1g), and 4,4′-methylenebis(cyclohexylamine) (0.4g) were added and mixed in appropriate proportions. To adjust the rheological and mechanical properties of the ink, fumed silica (SiO2, 20 nm particle size, 0.5g) was added to the mixture to optimize the ink's viscosity and printing performance. The mixture was dispersed in a high-speed disperser at 3000 rpm for 3 minutes to ensure thorough dispersion and the removal of air bubbles, resulting in a uniform ink suitable for UV-DIW printing.

[0083] Example 12 Except for step (2), the same procedures as in Example 1 are carried out, except that the amount of 4,4′-methylenebis(cyclohexylamine) used is 0.8 g.

[0084] The oligomer (10g), the photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (0.1g), and 4,4′-methylenebis(cyclohexylamine) (0.8g) were added and mixed in appropriate proportions. To adjust the rheological and mechanical properties of the ink, fumed silica (SiO2, 20 nm particle size, 0.5g) was added to the mixture to optimize the ink's viscosity and printing performance. The mixture was dispersed in a high-speed disperser at 3000 rpm for 3 minutes to ensure thorough dispersion and the removal of air bubbles, resulting in a uniform ink suitable for UV-DIW printing.

[0085] Example 13 Except for step (2), the same steps are as in Example 1. The difference from Example 1 is that the amount of fumed silica SiO2 used is 1 g.

[0086] The oligomer (10g), the photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (0.1g), and 4,4′-methylenebis(cyclohexylamine) (0.6g) were added and mixed in appropriate proportions. To adjust the rheological and mechanical properties of the ink, fumed silica (SiO2, 20 nm particle size, 1g) was added to the mixture to optimize the ink's viscosity and printing performance. The mixture was dispersed in a high-speed disperser at 3000 rpm for 3 minutes to ensure thorough dispersion and the removal of air bubbles, resulting in a uniform ink suitable for UV-DIW printing.

[0087] Example 14 Except for step (1), the same as Example 1 is performed. The difference from Example 1 is that the polyether polyol used is polyethanol.

[0088] Polyethanol (Mn = 2000 g / mol, 100 g, 0.05 mol), isophorone diisocyanate (22.29 g, 0.1 mol) and catalyst dibutyltin dilaurate (0.18 g, 0.0003 mol) were mixed and reacted at 50°C to prepare a prepolymer for 3 hours until the isocyanate group content stabilized.

[0089] 2-(tert-Butylamino)ethyl methacrylate TBAEMA (18.25 g, 0.1 mol) was reacted with the prepolymer and stirred at 50°C for 3 hours until the isocyanate groups reacted completely to obtain a polyurethane methacrylate-terminated oligomer.

[0090] Example 15 Except for step (1), the steps are the same as those in Example 1. The difference from Example 1 is that the polyether polyol used is polytetrahydrofuran.

[0091] A prepolymer was prepared by mixing polytetrahydrofuran (Mn = 2000 g / mol, 100 g, 0.05 mol), isophorone diisocyanate (22.29 g, 0.1 mol) and catalyst dibutyltin dilaurate (0.18 g, 0.0003 mol) and reacting them at 50°C for 3 hours until the isocyanate group content stabilized.

[0092] 2-(tert-Butylamino)ethyl methacrylate TBAEMA (18.25 g, 0.1 mol) was reacted with the prepolymer and stirred at 50°C for 3 hours until the isocyanate groups reacted completely to obtain a polyurethane methacrylate-terminated oligomer.

[0093] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A light-cured 3D printed isotropic high-toughness polyurethane elastomer, characterized in that: The composition of the isotropic high-toughness polyurethane elastomer includes 100 parts of polyurethane methacrylate end-capped oligomer and the following components in parts by mass: 0.1-10 parts of photoinitiator, 1-20 parts of amine chain extender, 0.1-20 parts of rheology modifier; The preparation method of the polyurethane methacrylate-terminated oligomer comprises the following steps: using polyether diol and isocyanate as raw materials, amine (meth)acrylate monomer as a blocking agent, and adding a catalyst to synthesize the polyurethane methacrylate-terminated oligomer, wherein the molar ratio of the polyether diol, isocyanate, amine (meth)acrylate monomer, and catalyst is 1:(1-2):(1-2):(0.001-0.05), and exemplarily 1:2:2:0.

006.

2. The light-cured 3D printing isotropic high-toughness polyurethane elastomer according to claim 1, characterized in that: The polyether diol comprises at least one of polypropylene glycol (PPG), polyethylene glycol (PEG) or polytetramethylene glycol (PTMEG), and the molecular weight of the polyether diol is independently 1000 to 4000; and / or The isocyanate comprises at least one of toluene diisocyanate TDI, isophorone diisocyanate IPDI, diphenylmethane diisocyanate MDI, dicyclohexylmethane diisocyanate HMDI or hexamethylene diisocyanate HDI; and / or The amine (meth)acrylate monomer blocking agent includes at least one of tert-butylaminoethyl methacrylate TBAEMA, tert-amylaminoethyl methacrylate TPAEMA, tert-hexylaminoethyl methacrylate THAEMA or tert-butylaminopropyl methacrylate TBAPMA and acrylate analogs thereof; and / or The catalyst includes a tin catalyst, and the tin catalyst includes at least one of stannous octoate DBTO, dibutyltin octoate DBTD or dibutyltin dilaurate DBDTL; and / or The light-cured 3D-printed isotropic high-toughness polyurethane elastomer according to claim 1, characterized in that the reaction temperature is 40 to 80° C., exemplified by 50° C., 60° C., or 70° C.; and / or The reaction time is 1-8 h, for example 3-6 h, exemplified by 3 h, 4 h, 5 h, and 6 h.

3. The light-cured 3D printing isotropic high-toughness polyurethane elastomer according to claim 1, characterized in that: The reaction process of the polyurethane methacrylate end-capped oligomer is as follows: Among them, HO-R1-OH represents polyether diols such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol, and OCN-R2-NCO represents diisocyanates such as isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate. H2C=C (CH3) CO2-R3-NH-R4 represents an amine (meth)acrylate such as tert-butylaminoethyl methacrylate, tert-amylaminoethyl methacrylate, tert-hexylaminoethyl methacrylate or tert-butylaminopropyl methacrylate, wherein R3 represents -(CH2)2- / -(CH2)3-, and R4 represents -C (CH3)3 / -C (CH3)2CH2CH3 / -C (CH3)2CH2CH2CH3.

4. The light-cured 3D printing isotropic high-toughness polyurethane elastomer according to claim 1, characterized in that: The photoinitiator includes at least one of 1-hydroxycyclohexylphenyl ketone HCPK, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide TPO, 2,4,6-trimethylbenzoyl-ethoxy-phenylphosphine oxide TPO-L, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide BAPO, 2,2-dimethoxy-1,2-diphenylethanone BDK, 2-ethyloctyl-4-dimethylaminobenzoate EDB or 4-p-toluene-2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone ITX; and / or The amine chain extender includes at least one of 4,4′-methylenebis(cyclohexylamine) H12MDA, ethylenediamine EDA, 1,4-butanediamine BDA, hexamethylenediamine HMDA, isophoronediamine IPDA, 1,3-diaminocyclohexane PACM or diphenylmethanediamine MDA; and / or The rheology modifier includes fumed silica SiO2.

5. The light-cured 3D printing isotropic high-toughness polyurethane elastomer according to claim 1, characterized in that: The photocurable 3D printed isotropic high-toughness polyurethane elastomer has a breaking strength of 5.3 MPa, an elongation at break of 1640%, and an anisotropy of <5%.

6. A method for preparing a light-cured 3D printed isotropic high-toughness polyurethane elastomer according to any one of claims 1 to 5, characterized in that: The following steps are involved: The polyurethane methacrylate end-capped oligomer, photoinitiator, gas silicon and amine chain extender are mixed to obtain a polyurethane acrylate 3D printing resin composition, which is then heat-treated to obtain an isotropic and high-toughness polyurethane elastomer.

7. The method according to claim 6, characterized in that The heat treatment temperature is 90-150°C, for example, 100-150°C, exemplified by 100°C, 120°C, and 150°C.

8. A triboelectric nanogenerator, characterized in that: It is prepared using the light-cured 3D printing isotropic high-toughness polyurethane elastomer described in any one of claims 1-5.

9. A method for preparing and packaging a triboelectric nanogenerator, characterized in that: The substrate, triboelectric layer and electrode layer of the friction nanogenerator are respectively prepared using the light-cured 3D-printed isotropic high-toughness polyurethane elastomer as described in any one of claims 1 to 5. The triboelectric layer, electrode layer, wire and substrate are stacked from top to bottom and placed in an oven for interlayer welding heat treatment to achieve packaging preparation.

10. The method according to claim 9, characterized in that The interlayer welding heat treatment time is 1 to 8 hours, for example, 2 to 8 hours, exemplified by 2 hours, 4 hours, 6 hours or 8 hours.

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