A polyurethane acrylate photosensitive resin containing a dynamic imine bond, and a preparation method and application thereof
The photosensitive polyurethane acrylate resin containing dynamic imine bonds, prepared by a microphase separation and multiple hydrogen bond synergistic strategy, solves the problem of balancing material strength, toughness, and self-healing in the DLP process. It achieves high strength, toughness, and self-healing functions in high-precision 3D printing materials, which are suitable for the manufacture of personalized medical assistive devices and flexible soft robots.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HENAN UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2026-05-15
- Publication Date
- 2026-07-07
AI Technical Summary
Existing recyclable photosensitive resins in DLP processes suffer from a homogeneous network, making it difficult to balance strength and toughness. The materials are prone to fatigue failure when subjected to large strains or cyclic loads, failing to meet the needs of practical engineering applications.
By employing a microphase separation and multiple hydrogen bond synergistic strategy, a polyurethane acrylate photosensitive resin containing dynamic imine bonds is prepared by introducing vanillin-derived diamine as a dynamic hard segment and polycarbonate diol as a flexible soft segment. The self-healing and shape memory functions of the intelligent device are then fabricated using digital light processing 3D printing technology.
It achieves a balance between high strength and high toughness, possesses efficient in-situ self-healing capability under mild conditions and near-non-destructive closed-loop reshaping capability, meets the requirements of long-term dynamic service, and has thermally induced shape memory effect, making it suitable for high-precision manufacturing.
Smart Images
Figure CN122344306A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of 3D printing materials technology, and particularly relates to a polyurethane acrylate photosensitive resin containing dynamic imine bonds, its preparation method and application. Background Technology
[0002] Photopolymer additive manufacturing technology, especially digital light processing (DLP) technology, has become the preferred solution for manufacturing complex three-dimensional structures due to its superior molding accuracy and excellent surface quality. However, the widespread application of this technology in the field of functional devices is still severely limited by the intrinsic defects of traditional photosensitive resins. To solve the problem of the non-recyclability of traditional photopolymer materials, researchers have successively introduced dynamic covalent chemistry (DCC) such as transesterification, disulfide bonds, and imine bonds (Schiff bases) into the photopolymer system, successfully endowing 3D printing materials with closed-loop recycling and self-healing capabilities. Among them, imine networks based on bio-based precursors such as vanillin have attracted much attention due to their mild conditions. However, existing recyclable photosensitive resins often exhibit extremely poor mechanical reliability in actual dynamic service. The fundamental scientific reason lies in the underlying conflict between the characteristics of the DLP process and the physical structure of the polymer. Limited by the stringent requirements of the DLP process for extremely low liquid viscosity, existing strategies are forced to rely heavily on directly modifying dynamic groups into low molecular weight photosensitive monomers. This compromise inevitably leads to the formation of a highly cross-linked homogeneous polymer network after photopolymerization. This homogeneous topology severely lacks effective energy dissipation mechanisms at the physical level, such as phase boundary friction and sacrificial bond breaking. Therefore, researchers attempting to improve macroscopic strength by increasing crosslink density easily fall into the trap of intrinsic material embrittlement; while blindly introducing flexible segments can increase toughness, it leads to a precipitous drop in modulus and strength. This pain point—the lack of dissipation mechanisms in homogeneous networks—makes it difficult to balance strength and toughness, causing existing dynamic printing materials to easily fail under large strain or cyclic loading, making it impossible to bridge the gap to practical engineering applications. Summary of the Invention
[0003] In view of this, the purpose of this invention is to provide a polyurethane acrylate photosensitive resin containing dynamic imine bonds, its preparation method, and its applications. This invention completely overcomes the problem of strength and toughness limitations caused by the homogeneous network in existing recyclable photosensitive resins. Abandoning the traditional homogeneous monomer design approach, it employs a microphase separation and multiple hydrogen bond synergistic strategy to successfully prepare a bio-based intelligent polyurethane acrylate resin suitable for high-precision DLP printing. This invention uses vanillin-derived diamine (VEG) as the dynamic hard segment and polycarbonate diol (PCDL) as the flexible soft segment to synthesize a polyurethane acrylate (PUA) photosensitive resin containing dynamic imine bonds through a stepwise polymerization reaction. Furthermore, it uses digital light processing (DLP) 3D printing technology to fabricate intelligent devices with self-healing and shape memory functions.
[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a polyurethane acrylate photosensitive resin containing dynamic imine bonds, which is prepared from the following raw materials in parts: 3-10 parts of polycarbonate diol, 9-11 parts of isophorone diisocyanate, 1-7 parts of 1,3-diaminopropane, 2-14 parts of 3-methoxy-4-hydroxybenzaldehyde, and 0.02-0.14 parts of p-toluenesulfonic acid monohydrate.
[0005] This invention also provides a method for preparing the above-mentioned polyurethane acrylate photosensitive resin containing dynamic imine bonds, comprising the following steps: 1) Mix 3-methoxy-4-hydroxybenzaldehyde, 1,3-diaminopropane, p-toluenesulfonic acid monohydrate and N,N-dimethylacetamide to obtain a mixture; 2) The mixture obtained in step 1) was subjected to reflux reaction under nitrogen protection. After the reaction was completed, the powdered intermediate vanillin-derived diamine was obtained by rotary evaporation. 3) Mix and stir the powdered intermediate vanillin-derived diamine obtained in step 2) with polycarbonate diol, N,N-dimethylacetamide, isophorone diisocyanate and dibutyltin dilaurate to obtain a mixed solution; The mixed solution obtained in step 4) is reacted with hydroquinone, hydroxyethyl acrylate, and N,N-dimethylacetamide, and then phenylbisphosphine oxide is added and stirred to obtain a polyurethane acrylate photosensitive resin containing dynamic imine bonds.
[0006] Preferably, the reflux reaction in step 2) is carried out at a temperature of 120°C for 24 hours.
[0007] Preferably, in step 3), the stirring temperature is 80°C, the stirring speed is 500 r / min, and the stirring time is not less than 3 h.
[0008] Preferably, the reaction temperature in step 4) is 80°C and the reaction time is 2 hours.
[0009] This invention also provides the application of the above-mentioned polyurethane acrylate photosensitive resin containing dynamic imine bonds in 3D printing.
[0010] This invention also provides the application of the above-mentioned polyurethane acrylate photosensitive resin containing dynamic imine bonds in the preparation of 3D printed products.
[0011] The present invention also provides an intelligent device with self-healing and shape memory functions, which is prepared by digital light processing 3D printing using the above-mentioned polyurethane acrylate photosensitive resin containing dynamic imine bonds.
[0012] The beneficial effects of this invention are: 1. The advanced manufacturing field urgently needs to develop photosensitive resins with green lifecycles and high toughness suitable for DLP printing. To completely overcome the core scientific challenge of "homogeneous network leading to toughness constraints" in existing recyclable photosensitive resins, this invention abandons the traditional homogeneous monomer design paradigm and proposes a polyurethane architecture strategy based on "microphase separation and multiple hydrogen bond synergy." This invention uses a dynamic Schiff base (VEG) derived from the condensation of vanillin and 1,3-propanediamine as a customized rigid hard segment, precisely embedded in a highly flexible UV-curable polyurethane (PUA) backbone, successfully developing a bio-based smart polyurethane acrylate (PUA) resin specifically for high-precision DLP 3D printing. This molecular-level design maintains the resin's ultra-low printing viscosity to perfectly adapt to high-precision DLP processes while inducing significant microphase separation structures through the VEG hard segments and polycarbonate soft segments. Thanks to the deep synergy of dense hydrogen bond physical dissipation and dynamic imine bond exchange within the microregions, this PUA material successfully breaks through the mechanical barriers of traditional resins, achieving an excellent balance between high strength and high toughness. Furthermore, the system exhibits highly efficient in-situ self-healing and near-lossless closed-loop remodeling capabilities under mild conditions, and its structure possesses an excellent thermo-induced shape memory effect based on a sensitive phase transition at body temperature.
[0013] 2. This invention solves the core problems of traditional photocurable materials, namely, their irreparability, non-recyclability, and difficulty in balancing strength and toughness. It also overcomes the shortcomings of existing dynamic materials, such as poor mechanical reliability and susceptibility to fatigue failure. The material features ultra-low printing viscosity, perfectly suited for DLP processes; through the synergistic effect of hydrogen bond physical dissipation and dynamic imine bond topological rearrangement in hard segment microregions, it achieves a balance between high strength and high toughness; it possesses efficient in-situ self-healing and near-non-destructive closed-loop recycling capabilities under mild conditions; and it exhibits excellent thermally induced shape memory effects close to body temperature, effectively overcoming fatigue failure and meeting the requirements of long-term dynamic service; using bio-based raw materials, it is green, sustainable, and environmentally friendly, and can be directly used for the high-precision manufacturing of personalized medical assistive devices and flexible soft robots, providing a new material solution and technical path for 4D printing intelligent equipment. Attached Figure Description
[0014] Figure 1 The physicochemical characterization, rheological and dynamic remodeling properties of bio-based PUA resins are as follows: (a) FTIR spectra of PUA and its precursors; (b) tensile stress-strain curves of different PUA formulations; (c) TGA curves; (d) rheological behavior of PUA resins with different DMAC contents; (e) DSC thermograms; (f) DMA temperature scans; (g) stress-strain curves of healed specimens; (h) stress-strain curves of recycled specimens; and (i) shape retention (Rf) and shape recovery (Rr) ratios over multiple cycles. Figure 2To demonstrate the self-healing and shape memory properties of intelligent PUA resin, (ab) a schematic diagram of the self-healing mechanism and an optical microscope image of the scratch healing process; (c) the 3D printed lattice structure and its macroscopic compression-recovery process; (d) a schematic diagram of the thermally induced shape memory cycling mechanism. Figure 3 The molecular design and cross-linking mechanism of bio-based dynamic PUA resin, including (a) the synthetic route and chemical structure of PUA prepolymers embedded with customized vanillin-derived imine hard segments (VEG); and (b) a schematic diagram of the dynamic three-dimensional network constructed by DLP 3D printing. Figure 4 To verify the engineering application of intelligent PUA materials, (a) the preparation process and application demonstration of a customized hallux valgus corrector; and (b) time-lapse photographs of the rapid contraction process of a line-driven soft actuator. Detailed Implementation
[0015] This invention provides a polyurethane acrylate photosensitive resin containing dynamic imine bonds, which is prepared from the following raw materials in parts: 3-10 parts of polycarbonate diol, 9-11 parts of isophorone diisocyanate, 1-7 parts of 1,3-diaminopropane, 2-14 parts of 3-methoxy-4-hydroxybenzaldehyde, and 0.02-0.14 parts of p-toluenesulfonic acid monohydrate.
[0016] The present invention does not have any special limitation on the source of the raw materials, and conventional commercially available products in the field can be used.
[0017] This invention also provides a method for preparing the above-mentioned polyurethane acrylate photosensitive resin containing dynamic imine bonds, comprising the following steps: 1) Mix 3-methoxy-4-hydroxybenzaldehyde, 1,3-diaminopropane, p-toluenesulfonic acid monohydrate and N,N-dimethylacetamide to obtain a mixture; 2) The mixture obtained in step 1) was subjected to reflux reaction under nitrogen protection. After the reaction was completed, the powdered intermediate vanillin-derived diamine was obtained by rotary evaporation. 3) Mix and stir the powdered intermediate vanillin-derived diamine obtained in step 2) with polycarbonate diol, N,N-dimethylacetamide, isophorone diisocyanate and dibutyltin dilaurate to obtain a mixed solution; The mixed solution obtained in step 4) is reacted with hydroquinone, hydroxyethyl acrylate, and N,N-dimethylacetamide, and then phenylbisphosphine oxide is added and stirred to obtain a polyurethane acrylate photosensitive resin containing dynamic imine bonds.
[0018] In this invention, the mixture is preferably refluxed at 120°C for 24 hours under nitrogen protection. After the reaction is completed, a powdered intermediate, vanillin-derived diamine (VEG), is obtained by rotary evaporation.
[0019] In this invention, the powdered intermediate vanillin-derived diamine is mixed and stirred with polycarbonate diol, N,N-dimethylacetamide, isophorone diisocyanate, and dibutyltin dilaurate. The stirring is preferably carried out at 80°C and 500 r / min until the initially turbid mixture becomes clear, and stirring is continued for 3 hours.
[0020] This invention also provides the application of the above-mentioned polyurethane acrylate photosensitive resin containing dynamic imine bonds in 3D printing.
[0021] This invention also provides the application of the above-mentioned polyurethane acrylate photosensitive resin containing dynamic imine bonds in the preparation of 3D printed products.
[0022] The present invention also provides an intelligent device with self-healing and shape memory functions, which is prepared by digital light processing 3D printing using the above-mentioned polyurethane acrylate photosensitive resin containing dynamic imine bonds.
[0023] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0024] Example 1 A method for preparing a polyurethane acrylate photosensitive resin containing dynamic imine bonds, the specific steps of which are as follows: 1. Material Preparation Polycarbonate diol (Mn=2000) was purchased from Ube Industries, Ltd., Japan. Isophorone diisocyanate (IPDI, 99%), 1,4-benzenediphenol (HQ, 99%), 1,3-diaminopropane (DI, 98%), phenyl bisphosphine oxide (BAPO, 97%), 3-methoxy-4-hydroxybenzaldehyde (VAN, 98%), hydroxyethyl acrylate (HEA, 95%), N,N-dimethylacetamide (DMAC, ≥99.9%), dibutyltin dilaurate (DBTDL, 98%), and p-toluenesulfonic acid monohydrate (PTSA, 98%) were all purchased from Aladdin Biochemical Technology Co., Ltd. (China). All chemicals were used directly without further purification.
[0025] 2. Resin Preparation Following standard procedures, VAN, DI, and PTSA were dissolved in DMAC in the proportions shown in Table 1 and thoroughly mixed. The mixture was refluxed at 120 °C for 24 hours under nitrogen protection. After the reaction was complete, the powdered intermediate VEG was obtained by rotary evaporation.
[0026] Subsequently, VEG and PCDL were mixed in DMAC, and IPDI (isophorone diisocyanate) and 2–3 drops of DBTDL were added. The solution was stirred at 80 °C (500 r / min) until the initially turbid mixture became clear, and stirring was continued for 3 hours. Afterward, 0.02 g hydroquinone, 20 mmol HEA, and 5 mL DMAC were added, and the reaction was carried out at 80 °C for 2 hours. Finally, 3 wt% BAPO was added to the system and stirred until homogeneous.
[0027] Table 1. Molar ratios for synthesizing different PUs
[0028] 3. DLP 3D Printing The 3D model was designed using SolidWorks software. The model was then sliced using Anycubic Photon Workshop software, with parameters listed in Table 2. The slice data was transferred to a high-resolution digital light processing (DLP) printer. Synthetic PU resin was filled into the resin tank, and the printing process was started. After printing, the samples were post-cured in a UV curing chamber for 15 minutes.
[0029] Table 2. Parameters for Photopolymerization 3D Printing
[0030] 4. Performance Testing and Verification Self-healing performance test: The sample was artificially cut and heat-treated in an oven at 60℃ for 12 hours. The crack healing was observed through an optical microscope, and the mechanical strength recovery rate after repair was tested through a tensile testing machine.
[0031] Shape memory performance test: The sample is heated to 85℃ to soften it, deformed by external force, and then rapidly cooled to 25℃ to fix the temporary shape. It is then heated to 85℃ again, and its shape recovery process is recorded. The shape fixation rate (Rf) and shape recovery rate (Rr) are calculated.
[0032] Closed-loop recycling test: Waste printed parts were pulverized and hot-pressed at 80℃ and 10 MPa pressure for 10 minutes to reshape them into new splines, and their mechanical property retention rate was tested. Furthermore, the material maintained extremely stable shape retention (Rf > 97%) and recovery rate (Rr > 99%) even after multiple cycles. (See results below) Figures 1 to 2 ).
[0033] The molecular design and cross-linking mechanism of the bio-based dynamic PUA resin of this invention (the principle of the printing process and the schematic diagram of the synthesis) can be found in [link to invention]. Figure 3 .
[0034] The engineering application verification of the intelligent PUA material of this invention (with scenario diagrams showing potential applications of this material in real life) can be found here. Figure 4 .
[0035] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A polyurethane acrylate photosensitive resin containing dynamic imine bonds, characterized in that, It is prepared from the following raw materials in parts: 3-10 parts polycarbonate diol, 9-11 parts isophorone diisocyanate, 1-7 parts 1,3-diaminopropane, 2-14 parts 3-methoxy-4-hydroxybenzaldehyde, and 0.02-0.14 parts p-toluenesulfonic acid monohydrate.
2. A method for preparing the polyurethane acrylate photosensitive resin containing dynamic imine bonds as described in claim 1, characterized in that, Includes the following steps: 1) Mix 3-methoxy-4-hydroxybenzaldehyde, 1,3-diaminopropane, p-toluenesulfonic acid monohydrate and N,N-dimethylacetamide to obtain a mixture; 2) The mixture obtained in step 1) was subjected to reflux reaction under nitrogen protection. After the reaction was completed, the powdered intermediate vanillin-derived diamine was obtained by rotary evaporation. 3) Mix and stir the powdered intermediate vanillin-derived diamine obtained in step 2) with polycarbonate diol, N,N-dimethylacetamide, isophorone diisocyanate and dibutyltin dilaurate to obtain a mixed solution; 4) The mixed solution obtained in step 4) is mixed with hydroquinone, hydroxyethyl acrylate and N,N-dimethylacetamide and reacted. Then, phenylbisphosphine oxide is added and stirred to obtain a polyurethane acrylate photosensitive resin containing dynamic imine bonds.
3. The method for preparing a polyurethane acrylate photosensitive resin containing dynamic imine bonds according to claim 2, characterized in that, In step 2), the reflux reaction temperature is 120°C and the time is 24 hours.
4. The method for preparing a polyurethane acrylate photosensitive resin containing dynamic imine bonds according to claim 2, characterized in that, In step 3), the stirring temperature is 80℃, the stirring speed is 500r / min, and the stirring time is not less than 3h.
5. The method for preparing a polyurethane acrylate photosensitive resin containing dynamic imine bonds according to claim 2, characterized in that, The reaction temperature in step 4) is 80℃ and the reaction time is 2h.
6. The application of the polyurethane acrylate photosensitive resin containing dynamic imine bonds as described in claim 1 in 3D printing.
7. The application of the polyurethane acrylate photosensitive resin containing dynamic imine bonds as described in claim 1 in the preparation of 3D printed products.
8. A smart device with self-healing and shape memory functions, characterized in that, The polyurethane acrylate photosensitive resin containing dynamic imine bonds described in claim 1 is prepared by digital light processing 3D printing.