3d printing composition based on raft and interpenetrating polymer network synergy

Abstract

This invention discloses a 3D printing composition based on the synergistic effect of RAFT and interpenetrating polymer networks, comprising a free radical crosslinking monomer, a diepoxy monomer, a RAFT chain transfer agent, and a cationic photoinitiator. The composition undergoes a synergistic reaction of RAFT polymerization and cationic ring-opening polymerization under light irradiation to form an interpenetrating polymer network structure. This invention selects specific ratios of free radical crosslinking monomer, diepoxy monomer, and RAFT chain transfer agent, and performs a synergistic reaction of RAFT polymerization and cationic ring-opening polymerization under light irradiation to form an interpenetrating polymer network structure, achieving a balance between strength and toughness. It maintains high toughness while maintaining high strength, thus meeting the requirements for both high strength and high toughness.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and more specifically to a 3D printing composition based on the synergy of RAFT and interpenetrating polymer networks. Background Technology

[0002] 3D printing technology, especially digital light processing (DLP) technology, is widely used in fields such as biomedicine, flexible electronics, and soft robotics due to its high resolution, rapid prototyping, and excellent surface quality. Traditional DLP printing resins mostly rely on a single polymerization mechanism, which has problems such as a narrow range of mechanical property control, poor uniformity of cross-linked networks, and insufficient toughness.

[0003] RAFT polymerization, as a "living" free radical polymerization method, can endow materials with post-modification capabilities. However, single RAFT polymerization systems have low crosslinking density and limited mechanical strength. Interpenetrating polymer networks can enhance and toughen materials through the entanglement of two networks. However, existing technologies make it difficult to achieve synergistic control of the polymerization process, making it difficult to match the strength and toughness of the materials. Furthermore, there is a lack of effective means to optimize the uniformity of the crosslinking network, which limits the precise control of material properties and practical applications. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a 3D printing composition based on the synergy of RAFT and interpenetrating polymer networks. By selecting specific ratios of free radical crosslinking monomers, diepoxy monomers, and RAFT chain transfer agents, a synergistic reaction of RAFT polymerization and cationic ring-opening polymerization is carried out under light irradiation to form an interpenetrating polymer network structure, achieving a balance between strength and toughness. This results in high strength while maintaining high toughness, thus meeting the requirements for both high strength and high toughness.

[0005] To address the aforementioned technical problems, the first aspect of this invention provides a 3D printing composition based on the synergistic reaction of RAFT and interpenetrating polymer networks, comprising a free radical crosslinking monomer, a diepoxy monomer, a RAFT chain transfer agent, and a cationic photoinitiator; the composition undergoes a synergistic reaction of RAFT polymerization and cationic ring-opening polymerization under light irradiation to form an interpenetrating polymer network structure.

[0006] Furthermore, the diepoxy monomer is ECC (epoxycyclohexylmethylepoxycyclohexane carboxylate), with the structural formula as follows: .

[0007] Furthermore, the free radical crosslinking monomer is polyethylene glycol diacrylate (PEGDA). 200 ), the structural formula is , where n is an integer.

[0008] Furthermore, the cationic photoinitiator is triarylsulfonium hexafluoroantimonate (PAG-SbF6) and 2-isopropylthioxanthone (ITX), with the following structural formulas: , .

[0009] Furthermore, the RAFT chain transfer agent is ethyl 2-((ethoxycarbonylthio)thio)propionate (EXEP), with the structural formula as follows: .

[0010] Furthermore, the molar ratio of the free radical crosslinking monomer, the diepoxy monomer, the RAFT chain transfer agent, and the cationic photoinitiator is a:b:(1-20):0.04b:0.02b, where a+b=100.

[0011] This invention preferably uses specific free radical crosslinking monomers, diepoxy monomers, RAFT chain transfer agents, and cationic photoinitiators. Under light irradiation, RAFT polymerization and cationic ring-opening polymerization are carried out in a synergistic reaction to form an interpenetrating polymer network structure. Unlike the covalent bonds in a dual crosslinked network, the interpenetrating polymer network has physical entanglement on the crosslinked network without any chemical bonds. By utilizing the energy dissipation of physical entanglement, the Young's modulus of the material can be precisely controlled within the range of 12.98 MPa to 2463.17 MPa, with a control factor of more than 190 times. At the same time, it also has excellent toughness (up to 1876.35 MPa). In contrast, the toughness of the dual crosslinked network in the prior art is only 486 MPa when the Young's modulus reaches 2.26 GPa. It can be seen that the composition of this invention can achieve a high strength and high toughness match.

[0012] This invention uses EXEP RAFT chain transfer agent, which can effectively optimize the uniformity of crosslinking network. As its content increases, the network FWHM gradually decreases, significantly improving the structural stability of the material while maintaining high toughness.

[0013] This invention allows for flexible adjustment of the material's hardness, strength, and toughness by modifying the composition ratio and curing time, thus adapting to the needs of different application scenarios. Simultaneously, the composition exhibits good stability and a printing accuracy of up to 50μm, making it suitable for multifunctional 3D printing applications such as soft robots, biomimetic structures, and flexible electronics.

[0014] A second aspect of this invention provides a 3D printing method based on the synergy of RAFT and interpenetrating polymer networks, comprising the following steps:

[0015] S1. Mix the composition described in the first aspect in a certain proportion to obtain a photosensitive resin;

[0016] S2. Place the photosensitive resin in the 3D printer, import the model file and set the printing parameters;

[0017] S3. Layer-by-layer photopolymerization printing yields a three-dimensional polymer structure.

[0018] Furthermore, the printing parameters are: layer thickness 50-100μm, exposure time 185-200s.

[0019] Furthermore, the light source for photocuring is 400-420nm.

[0020] Furthermore, the photocuring process includes a post-curing step, which takes 120-240 minutes.

[0021] The beneficial effects of this invention are:

[0022] The present invention preferably uses a specific ratio of free radical crosslinking monomer, diepoxy monomer, RAFT chain transfer agent and cationic photoinitiator to form a photosensitive composition. Under light irradiation, RAFT polymerization and cationic ring-opening polymerization are carried out in a synergistic reaction to form an interpenetrating polymer network structure, which achieves a match between strength and toughness. It maintains high toughness while maintaining high strength, thus meeting the requirements of high strength and high toughness.

[0023] This invention allows for flexible adjustment of material strength and toughness by modifying the composition ratio and curing time to meet the needs of different application scenarios. At the same time, the composition exhibits good stability and a printing accuracy of up to 50 μm, making it suitable for multifunctional 3D printing applications such as soft robots, biomimetic structures, and flexible electronics. Attached Figure Description

[0024] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a tensile property test diagram of the polymer structure obtained in Example 1 of the present invention;

[0026] Figure 2 In Embodiment 3 of the present invention, when x=1, the [PEGDA] is different. 200 Tensile property test diagram of polymer structures obtained by [ECC] formulation;

[0027] Figure 3 In Embodiment 3 of the present invention, when x=10, the [PEGDA] is different. 200 Tensile property test diagram of polymer structures obtained by [ECC] formulation;

[0028] Figure 4 In Embodiment 3 of the present invention, when x=20, the [PEGDA] is different.200 Tensile property test diagram of polymer structures obtained by [ECC] formulation;

[0029] Figure 5 These are tensile property test diagrams of polymer structures obtained at different post-curing times in Example 4 of the present invention. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. 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.

[0031] This embodiment relates to a 3D printing composition based on the synergistic reaction of RAFT and interpenetrating polymer networks, comprising a free radical crosslinking monomer, a diepoxy monomer, a RAFT chain transfer agent, and a cationic photoinitiator; the composition undergoes a synergistic reaction of RAFT polymerization and cationic ring-opening polymerization under light irradiation to form an interpenetrating polymer network structure.

[0032] In a preferred embodiment, the diepoxy monomer is ECC (epoxycyclohexylmethylepoxycyclohexane carboxylate), with the structural formula: The free radical crosslinking monomer is polyethylene glycol diacrylate (PEGDA). 200 ), the structural formula is n is an integer; the cationic photoinitiator is triarylsulfonium hexafluoroantimonate (PAG-SbF6) and 2-isopropylthioxanthone (ITX), with the following structural formulas respectively: , The RAFT chain transfer agent is ethyl 2-((ethoxycarbonylthio)thio)propionate (EXEP), with the following structural formula: .

[0033] In a preferred embodiment, the molar ratio of the free radical crosslinking monomer, the diepoxy monomer, the RAFT chain transfer agent, and the cationic photoinitiator is a:b:(1-20):0.04b:0.02b, where a+b=100.

[0034] This embodiment preferably uses specific free radical crosslinking monomers, diepoxy monomers, RAFT chain transfer agents, and cationic photoinitiators. RAFT polymerization and cationic ring-opening polymerization are carried out under light irradiation to form an interpenetrating polymer network structure. Unlike the covalent bonds in a dual crosslinked network, the interpenetrating polymer network consists of physical entanglements on the crosslinked network without any chemical bonds. This physical entanglement dissipates energy, allowing for precise control of the Young's modulus within the range of 12.98 MPa to 2463.17 MPa, with a control factor exceeding 190 times. Simultaneously, it exhibits excellent toughness (up to 1876.35 MPa). In contrast, existing dual crosslinked networks achieve a Young's modulus of only 2.26 GPa with a toughness of only 486 MPa. Therefore, the composition of this invention achieves a high strength and high toughness balance. The use of EXEP RAFT chain transfer agents effectively optimizes the uniformity of the crosslinked network. As its content increases, the network free wave size (FWHM) gradually decreases, significantly improving the structural stability of the material while maintaining high toughness. By adjusting the composition ratio and curing time, the hardness, strength, and toughness of the material can be flexibly adjusted to meet the needs of different application scenarios. At the same time, the composition has good stability and the printing accuracy can reach 50 μm, making it suitable for multifunctional 3D printing applications such as soft robots, biomimetic structures, and flexible electronics.

[0035] Another embodiment relates to a 3D printing method based on RAFT and interpenetrating polymer networks, comprising the following steps:

[0036] S1. Mix the composition described in the first aspect in a certain proportion to obtain a photosensitive resin;

[0037] S2. Place the photosensitive resin in the 3D printer, import the model file and set the printing parameters;

[0038] S3. Layer-by-layer photopolymerization printing yields a three-dimensional polymer structure.

[0039] As a preferred embodiment, the printing parameters are: layer thickness 50-100 μm, exposure time 185-200s, the light source for photocuring is 400-420 nm, and the photocuring printing process further includes a post-curing step with a time of 120-240 min.

[0040] Example 1

[0041] This embodiment relates to a method for 3D printing interpenetrating networks with different EXEP contents, including the following steps:

[0042] Molecular ratio [PEGDA] 200Three photosensitive resins were prepared by mixing [ECC]:[EXEP]:[PAG-SbF6]:[ITX] = 70:30:x:1.2:0.6 (x=1, 10, 20). 50 mL of each resin was placed in the feed tank of a DLP 3D printer. Printing parameters were set as follows: layer thickness 100 μm, layer exposure time 190 s, bottom layer (1), bottom layer exposure time 200 s, anti-aliasing (1), Z-axis lift height 5 mm, and 2 mm s. -1 Z-axis lifting speed, 2 mm / s -1 (Z-axis retraction speed), then perform the printing process to prepare the polymer structure, and post-curing (LED 405nm) for 180 min to obtain a dumbbell-shaped sample.

[0043] The polymer structure obtained in Example 1 was subjected to tensile property testing, and the test results are as follows: Figure 1 As shown. The tensile property test method is as follows:

[0044] Mechanical testing was conducted on an electronic tensile testing machine (Instron) equipped with a 50-N load cell. At room temperature, the tensile test was performed at 2.0 mm / min. -1 Tensile tests were conducted at a crosshead speed. Tensile strength was calculated by dividing the maximum load (N) by the average original cross-sectional area (m²) within the gauge length of the specimen. 2 The elongation at break is calculated by dividing the elongation at the fracture point of the specimen by the original gauge length and multiplying by 100.

[0045] The performance test results of the polymer structure obtained in Example 1 are as follows:

[0046] When x=1, the Young's modulus is 671.98±28.21MPa, the toughness is 238.04±21.10MPa, and the FWHM is 42.0817.

[0047] When x=10, the Young's modulus is 365.87±28.06MPa, the toughness is 230.68±10.43MPa, and the FWHM is 35.4511;

[0048] When x=20, the Young's modulus is 12.98±2.49MPa, the toughness is 46.16±3.39MPa, and the FWHM is 26.1038.

[0049] Example 2

[0050] The difference between this embodiment and Embodiment 1 is that [PEGDA] 200[ECC]:[EXEP]:[PAG-SbF6]:[ITX]= 50:50:x:2:1 (x=1, 10, 20), with other steps and parameters unchanged, the performance test of the prepared polymer structure is as follows:

[0051] When x=1, the Young's modulus is 1817.81±33.23MPa, the toughness is 1876.35±117.32MPa, and the FWHM is 92.2102.

[0052] When x=10, the Young's modulus is 838.88±25.09MPa, the toughness is 1159.11±89.76MPa, and the FWHM is 74.0517;

[0053] When x=20, the Young's modulus is 173.94±25.68MPa, the toughness is 223.38±15.10MPa, and the FWHM is 47.1989.

[0054] As shown in Examples 1 and 2, with the increase of EXEP content, the crosslinking network FWHM gradually decreases, and the network uniformity is significantly improved; at the same time, when [PEGDA] 200 The formula ]:[ECC]:[EXEP]:[PAG-SbF6]:[ITX] = 50:50:1:2:1 combines excellent Young's modulus and toughness, solving the problem of poor toughness in existing double crosslinked networks when Young's modulus is high.

[0055] Example 3

[0056] This embodiment involves different [PEGDA] 200 The method for 3D printing interpenetrating network (IPN) with [ECC] ratio includes the following steps:

[0057] Molecular ratio [PEGDA] 200 The photosensitive resin was prepared using the formula: [ECC]:[EXEP]:[PAG-SbF6]:[ITX]= a:b:x:0.04b:0.02b (a=70, 60, 50, 40, 30; b=30, 40, 50, 60, 70; x=1, 10, 20). Printing parameters were the same as in Example 1, followed by post-curing (LED 405nm) for 180 min. Tensile test results are as follows... Figure 2-4 As shown, where:

[0058] When a=30, b=70, and x=1, the Young's modulus reaches its maximum value of 2463.17±122.24MPa, and the toughness is 1436.76±95.03MPa.

[0059] When a=50, b=50, and x=10, the Young's modulus is 838.88±25.09MPa, and the toughness is 1159.11±89.76MPa.

[0060] When a=70, b=30, and x=10, the Young's modulus is 365.87±28.06MPa and the toughness is 230.68±10.43MPa.

[0061] Under these conditions, the range of Young's modulus and toughness is wide, and high strength and high toughness can be achieved, making up for the shortcomings of the inability to unify strength and toughness.

[0062] Example 4

[0063] This embodiment relates to a 3D printing method for interpenetrating networks with different post-curing times, including the following steps:

[0064] Molecular ratio [PEGDA] 200 A photosensitive resin was obtained by mixing [ECC]:[EXEP]:[PAG-SbF6]:[ITX] = 50:50:10:2:1. The printing parameters were the same as in Example 1, and then the resin was cured (LED 405nm) for 30 min, 120 min, 180 min, 240 min, and 360 min respectively (same as in Example 3). The test results are as follows... Figure 5 As shown, the results indicate that the Young's modulus of the material reaches a plateau after 180 min of post-curing. Therefore, post-curing for 180 min is preferred, as it significantly improves upon the uncured sample.

[0065] In summary, this invention preferably uses a specific ratio of free radical crosslinking monomers, biepoxide monomers, RAFT chain transfer agents, and cationic photoinitiators to form a photosensitive composition. Under light irradiation, RAFT polymerization and cationic ring-opening polymerization undergo a synergistic reaction to form an interpenetrating polymer network structure, achieving a balance between strength and toughness. It maintains high toughness while maintaining high strength, meeting the requirements for both. By adjusting the composition ratio and curing time, the material strength and toughness can be flexibly adjusted to adapt to different application scenarios. Simultaneously, the composition exhibits good stability and a printing accuracy of up to 50 μm, making it suitable for multifunctional 3D printing applications such as soft robots, biomimetic structures, and flexible electronics.

[0066] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A 3D printing composition based on RAFT and interpenetrating polymer network synergy, characterized in that, Including free radical crosslinking monomers, diepoxy monomers, RAFT chain transfer agents, and cationic photoinitiators; The composition undergoes a synergistic reaction of RAFT polymerization and cationic ring-opening polymerization under light irradiation to form an interpenetrating polymer network structure.

2. The 3D printing composition based on RAFT and interpenetrating polymer network synergy as described in claim 1, characterized in that, The bis-epoxy monomer is .

3. The RAFT and interpenetrating polymer network synergized based 3D printing composition as claimed in claim 1, wherein, The free radical crosslinking monomer is polyethylene glycol diacrylate.

4. The RAFT and interpenetrating polymer network based synergistic 3D printing composition according to claim 1, wherein, The cationic photoinitiator is triarylsulfonium hexafluoroantimonate and 2-isopropylthioxanthone.

5. The RAFT and interpenetrating polymer network synergized based 3D printing composition as claimed in claim 1, wherein, The RAFT chain transfer agent is ethyl 2-((ethoxycarbonylthio)thio)propionate.

6. The RAFT and interpenetrating polymer network synergized based 3D printing composition as claimed in claim 1, wherein, The molar ratio of the free radical crosslinking monomer, the diepoxy monomer, the RAFT chain transfer agent, and the cationic photoinitiator is a:b:(1-20):0.04b:0.02b, where a+b=100 and 30≤b≤70.

7. A 3D printing method based on RAFT and interpenetrating polymer networks, characterized in that, Includes the following steps: S1. Mix the composition according to any one of claims 1-6 in a certain proportion to obtain a photosensitive resin; S2. Place the photosensitive resin in the 3D printer, import the model file and set the printing parameters; S3. Layer-by-layer photopolymerization printing yields a three-dimensional polymer structure.

8. The RAFT and interpenetrating polymer network based synergistic 3D printing method according to claim 7, wherein, The printing parameters are: layer thickness 50-100μm, exposure time 185-200s.

9. The RAFT and interpenetrating polymer network synergized based 3D printing method according to claim 7, wherein, The light source for photopolymerization is 400-420nm.

10. The 3D printing method based on RAFT and interpenetrating polymer networks as described in claim 7, characterized in that, The photopolymer printing process also includes a post-curing step.

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