Resin for digital light processing 3D printing

Abstract

To provide a resin for digital light processing (DLP) 3D printing.SOLUTION: A resin for grayscale DLP 3D printing includes a donor moiety, an acceptor moiety, a rigid moiety, a photoinitiator, and a photoabsorber. The donor moiety is an acrylate monomer with a side group of a free carbonyl, a primary amine on an acrylate, a secondary amine on an acrylate, and / or a tertiary amine on an acrylate. The acceptor moiety is different than the donor moiety and is an acrylate monomer with a side group of a free hydroxy, a primary amine, a secondary amine, and / or an imine. And the rigid moiety is an acrylate monomer with a side group of a cyclohexyl, a substituted cyclohexyl, or a bicyclic structure. A monolithic structure formed from the resin using the grayscale DLP 3D printing can have a Young's modulus ranging from 0.1 MPa to 100 MPa.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Technical field This disclosure relates, in general, to resins, and more particularly to resins for digital light processing 3D printing. [Background technology]

[0002] background Digital light processing three-dimensional (DLP) 3D printing is a vat polymerization technique that constructs 3D parts by curing layers of resin one by one using a digital light projector. Grayscale DLP 3D (g-DLP 3D) printing uses grayscale light patterns to obtain graded functional materials. However, current resins have a limited range of hardness and elasticity that can be obtained.

[0003] To address these issues and other problems associated with g-DLP 3D printing, this disclosure proposes a resin for g-DLP 3D printing. [Overview of the project] [Means for solving the problem]

[0004] overview In one embodiment of the present disclosure, the resin for 3D printing comprises a donor site, a receiving site, and a rigid site. The donor site is in the form of an acrylate monomer having a side group comprising at least one of a free carbonyl, a primary amine on an acrylate, a secondary amine on an acrylate, and a tertiary amine on an acrylate. The receiving site is different from the donor site and is in the form of an acrylate monomer having a side group comprising at least one of a free hydroxyl, a primary amine, a secondary amine, and an imine. The rigid site is in the form of an acrylate monomer having a side group comprising one or more of a cyclohexyl, a substituted cyclohexyl, and a bicyclic structure. The resin comprises a photoinitiator and a light absorber and is configured to form a solid polymer having a Young's modulus in the range of 0.1 MPa to 100 MPa using grayscale digital light processing 3D printing.

[0005] In another embodiment of the present disclosure, the resin for 3D printing comprises a donor site, a receiving site, and a rigid site. The donor site is selected from the group consisting of 2-hydroxyethyl acrylate, caprolactone acrylate, hydroxypropyl acrylate, 2,3-dihydroxypropyl acrylate, 1,3-dihydroxypropyl acrylate, N-hydroxyethyl acrylamide, and diacrylates based on aliphatic urethanes. The receiving site is selected from the group consisting of diacrylates based on aliphatic urethanes and 2-hydroxyethyl acrylate. The rigid site is selected from the group consisting of isobornyl acrylate, 4-acryloylmorpholine, methyl methacrylate, 2-hydroxyethyl methacrylate, and isobornyl methacrylate. The resin also comprises a photoinitiator and a light absorber and is configured to form a solid polymer having a Young's modulus in the range of 0.1 MPa to 200 MPa using grayscale digital light processing 3D printing.

[0006] In yet another embodiment of the present disclosure, the resin for 3D printing comprises a donor site, a receiving site, and a rigid site. The donor site comprises 2-hydroxyethyl acrylate, the receiving site comprises a diacrylate based on an aliphatic urethane, and the rigid site comprises isobornyl acrylate. The resin also comprises a photoinitiator and a light absorber and is configured to form a solid polymer having a Young's modulus in the range of 0.1 MPa to 300 MPa using grayscale digital light processing 3D printing.

[0007] The above-described and other characteristics of the composite salt mixture and its preparation will become apparent from the following detailed description and the illustrative, non-limiting drawings and examples.

[0008] Brief explanation of the drawing A more complete understanding of the teachings of this invention will be achieved through the detailed description and accompanying drawings. [Brief explanation of the drawing]

[0009] [Figure 1] This shows a g-DLP 3D printer. [Figure 2A] The present disclosure shows a resin relating to the teachings of this disclosure, having hydrogen bonds between a donating portion, a receiving portion, and a rigid portion. [Figure 2B] Figure 2A shows a resin having crosslinks between the donating portion, the receiving portion, and the rigid portion. [Figure 3A] This is a photograph of a snail structure manufactured using a g-DLP 3D printer with the resin described in the teachings of this disclosure. [Figure 3B] Figure 3A is a photograph of a snail structure, which has a first soft part (neck) that is stretched or elongated by 400%, and a second soft part (shell) that is under load but maintains its shape. [Figure 4A]These are stress and strain plots for tensile test specimens manufactured using the resin described in this disclosure, printed on a g-DLP 3D printer at 0% grayscale level (indicated as "G0"), 10% grayscale level (indicated as "G10"), 20% grayscale level (indicated as "G20"), 30% grayscale level (indicated as "G30"), 40% grayscale level (indicated as "G40"), and 50% grayscale level (indicated as "G50"). [Figure 4B] These are stress and strain plots for tensile specimens manufactured using the resin described in this disclosure, printed on a g-DLP 3D printer at 60% grayscale level (indicated as "G60") and 70% grayscale level (indicated as "G70"). [Figure 4C] This is a plot of stress and cycle count for a "G60" tensile specimen manufactured by g-DLP 3D printing using the resin described in this disclosure and subjected to strain cycles of 200% to 300%. [Figure 5A] This is a plot of Young's modulus, glass transition temperature, and grayscale percentage values ​​for tensile samples made from conventional materials and tensile samples manufactured by printing with a g-DLP 3D printer using the resins taught in this disclosure at grayscale levels G0, G10, G20, G30, G40, G50, G60, and G70. [Figure 5B] This is a plot of Young's modulus and percentage elastic elongation of tensile specimens fabricated by g-DLP 3D printing using the resins taught in this disclosure, compared to other conventional materials. [Figure 6A] This is a stress and strain plot for a pair of composite-like structures manufactured using a g-LPD 3D printer with the resin described in the teachings of this disclosure (a pair of composite-like structures). [Figure 6B] This is a set of photographs showing the composite-like structure tested in Figure 6A with a 200-gram (g) weight attached. [Figure 6C] This is a series of photographs showing an airless tire manufactured using a g-LPD 3D printer with the resin relating to the teachings of this disclosure. [Figure 7A] Schematic diagrams of three different mimetic arterial tissues are shown. [Figure 7B] A plot of stress and strain when three mimetic arterial tissues manufactured with a g-LPD 3D printer using the resin according to the teachings of the present disclosure were subjected to a tensile test. [Figure 8A] A plot of load and displacement for a three-zone structure manufactured with a g-LPD 3D printer using the resin according to the teachings of the present disclosure, the three-zone structure having rigid fibers of G0 in the shape of a spring embedded in a first zone of a G66 matrix, a second zone of a G56 matrix, and a third zone of a G46 matrix. [Figure 8B] A plot of the strain of each zone of the three-zone structure against the displacement of the entire three-zone structure in FIG. 8A. [Figure 9] A series of photographs showing an artificial human heart valve manufactured with a g-LPD 3D printer using the resin according to the teachings of the present disclosure. [Figure 10] A series of photographs and FEA simulations of the structure of a fish fin manufactured with a g-LPD 3D printer using the resin according to the teachings of the present disclosure. [Figure 11A] A series of photographs showing three biomimetic structures manufactured with a g-LPD 3D print using the resin according to the teachings of the present disclosure. [Figure 11B] A plot of load and displacement for the three biomimetic structures in FIG. 11A. [Figure 12A] A set of photographs showing a pufferfish before and after inflation. [Figure 12B] A set of photographs showing before and after inflation of a biomimetic pufferfish manufactured with a g-LPD 3D printer using the resin according to the teachings of the present disclosure. [Figure 13A] Photographs and FEA simulations of a membrane structure having a rigid cap and a soft membrane manufactured with a g-LPD 3D printer using the resin according to the teachings of the present disclosure. [Figure 13B]These are photographs and FEA simulations of a membrane structure having a rigid cap and a single coaxial rigid ring within a soft membrane, fabricated using a g-LPD 3D printer with the resin described in this instruction. [Figure 13C] These are photographs and FEA simulations of a membrane structure, manufactured using a g-LPD 3D printer with the resin described in this instruction, which has a rigid cap and four coaxial rigid rings within a soft membrane. [Figure 13D] These are photographs and FEA simulations of a membrane structure having a rigid cap and three coaxial 1 / 3-circular rigid rings within a soft membrane, manufactured using a g-LPD 3D printer with the resin described in the teachings of this disclosure. [Figure 14A] The images show a schematic diagram of a cylindrical membrane structure having a horizontal rigid ring, a photograph of the cylindrical membrane structure having a horizontal rigid ring manufactured using a g-LPD 3D printer with the resin taught in this disclosure before inflation, and a photograph of the cylindrical membrane structure having a horizontal rigid ring after inflation. [Figure 14B] The images show a schematic diagram of a cylindrical membrane structure having a horizontal rigid ring and vertical rigid fibers, a photograph of the cylindrical membrane structure having a horizontal rigid ring and vertical rigid fibers manufactured using a g-LPD 3D printer with the resin taught in this disclosure before inflation, and a photograph of the cylindrical membrane structure having a horizontal rigid ring and vertical rigid fibers after inflation. [Figure 14C] The images show a schematic diagram of a cylindrical membrane structure having vertically oriented rigid fibers, a photograph of the cylindrical membrane structure having vertically oriented rigid fibers manufactured using a g-LPD 3D printer with the resin taught in this disclosure before inflation, and a photograph of the cylindrical membrane structure having vertically oriented rigid fibers after inflation. [Figure 14D] The images show a schematic diagram of a cylindrical membrane structure having a helical rigid ring, a photograph of the cylindrical membrane structure having a helical rigid ring manufactured using a g-LPD 3D printer with the resin taught in this disclosure before inflation, and a photograph of the cylindrical membrane structure having a helical rigid ring after inflation. [Figure 15A]The diagram shows a schematic of a cylindrical membrane structure having a horizontal rigid ring and vertical helical rigid fibers, and the photograph shows the cylindrical membrane structure having a horizontal rigid ring and vertical helical rigid fibers before inflation, which was manufactured using a g-DLP 3D printer with the resin taught in this disclosure. [Figure 15B] Figure 15A is a series of photographs showing how a cylindrical membrane structure, which has a horizontal rigid ring and vertical helical rigid fibers, forms a tentacle shape while being inflated. [Figure 15C] Figure 15A shows a photograph of a cylindrical membrane structure, which has a horizontal rigid ring and vertical helical rigid fibers, holding a marker pen. [Figure 15D] Figure 15A shows a photograph of a cylindrical membrane structure, which has a horizontal rigid ring and vertical helical rigid fibers, holding a marker pen. [Modes for carrying out the invention]

[0010] The drawings described herein are intended to illustrate, for the purpose of describing specific embodiments, general characteristics of the composite salt mixtures and electrolytes in the art relating to this disclosure. These drawings may not accurately reflect the characteristics of any particular embodiment and are not necessarily intended to specify or limit specific forms or modifications within the scope of this art.

[0011] Detailed explanation This disclosure provides a resin for single-vat single-cure g-DLP 3D printing. This resin has a composition that results in a highly extensible, soft organogel portion and a hard, thermosetting portion within a single print layer. In addition, the resin enables the production of monolithic 3D printed components having one or more extensible (elastic) soft organogel portions and one or more hard, thermosetting portions, without requiring the use of multiple vats containing different resins.

[0012] In several modifications, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 10 MPa to approximately 100 MPa. In at least one modification, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 10 MPa to approximately 200 MPa. In several modifications, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 10 MPa to approximately 300 MPa. And in at least one modification, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 10 MPa to approximately 400 MPa, or approximately 10 MPa to approximately 478 MPa.

[0013] In several modifications, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 8 MPa to approximately 100 MPa. In at least one modification, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 5 MPa to approximately 100 MPa. In several modifications, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 2 MPa to approximately 100 MPa. And in at least one modification, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 1 MPa to approximately 100 MPa, or approximately 0.5 MPa to approximately 100 MPa, or approximately 0.1 MPa to approximately 100 MPa.

[0014] In several modifications, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 5 MPa to approximately 200 MPa. In at least one modification, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 2 MPa to approximately 200 MPa. In several modifications, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 1 MPa to approximately 300 MPa. And in at least one modification, a monolithic structure manufactured using a g-DLP 3D printer with the resin taught in this disclosure exhibits a Young's modulus in the range of approximately 0.5 MPa to approximately 400 MPa, or approximately 0.1 MPa to approximately 475 MPa.

[0015] In some modifications, monolithic structures manufactured by a g-DLP 3D printer using the resins taught in this disclosure exhibit elastic elongation up to 100%. In some modifications, monolithic structures manufactured by a g-DLP 3D printer using the resins taught in this disclosure exhibit elastic elongation up to 200%, up to 300%, up to 400%, up to 450%, or greater than 450%. In other words, monolithic structures manufactured by g-DLP 3D printing using the resins taught in this disclosure have at least one portion having low hardness and high elasticity, and at least one portion having high hardness and high strength, details of which are described below.

[0016] It should be understood that 3D printing enables the creation of geometrically and materially complex components and structures that were physically and / or economically impossible with conventional manufacturing techniques such as casting, machining, cryogenic processing, and high-temperature processing. Furthermore, the capabilities of new 3D printing have demonstrated its use in functional applications or structures such as deployable structures, soft robotics, flexible electrical components, and biomimetic designs. However, many functional applications, such as natural product-like structures, airless tires, multi-stable absorbers, and 4D printing, require the use of multiple materials with significantly different properties. That is, in such structures, different parts must, or need, have, significantly different mechanical and / or physical properties.

[0017] It should also be understood that DLP 3D printing is a high-speed, high-resolution printing method that has become increasingly popular in recent years. Digital light processing uses a projector to irradiate hundreds or thousands of thin layers of resin with a predetermined cross-section of a solid part, curing each layer one by one to produce the solid part layer by layer. In a typical DLP printing process, one resin vat is used, and only movement of the build plate in the z-direction is required to form the component, with photopolymerization (or photocuring) of the thin layers occurring in seconds. Therefore, DLP 3D printing is one of the fastest 3D printing technologies. However, because it uses one resin vat, DLP is generally not suitable for printing parts with multiple material properties. Methods have been developed to print two or more materials by using multiple vats and moving the printed parts between them. However, cross-contamination occurs between multiple vats, and switching between different resin vats and cleaning significantly slows down the printing speed.

[0018] In g-DLP printing, the degree of local monomer conversion (curing) is controlled by the intensity of light, and this light intensity is manipulated at the pixel level by an input grayscale image. For example, referring to Figure 1, a g-DLP 3D printer 10 is shown having a projector 100, a build platform 120, and a resin vat 140 containing a resin 150 as taught in this disclosure. The projector 100 is configured to project a grayscale image onto the transparent bottom wall 142 of the resin vat 140, so that a layer of resin 150 having a predetermined cross-section of component "C" is irradiated and cured. Once the layer of resin 150 is irradiated (and cured) by grayscale exposure from the projector 100, the build platform 120 moves in the illustrated +z direction so that the resin 150 flows between the nearly cured resin layer and the upper surface 143 of the transparent bottom wall 142. Next, the projector 100 projects another grayscale image onto the transparent bottom wall 142 of the resin vat 140, thereby illuminating the newest layer of resin 150 with a predetermined cross-section of component "C". This process or cycle continues until component C is manufactured layer by layer and completed.

[0019] Referring to Figures 2A and 2B, a non-limiting example of three monomers contained in resin 150 in the resin is shown. In particular, resin 150 comprises at least one hydrogen bond donating monomer 152 (2-hydroxyethyl acrylate as shown), at least one hydrogen bond receiving monomer 154 (diacrylate based on aliphatic urethane as shown), and at least one rigid monomer 156 (isobornyl acrylate as shown). In some variations, at least one hydrogen bond donating monomer 152 may be a different hydrogen bond receiving monomer from at least one hydrogen bond receiving monomer 154, and / or at least one hydrogen bond receiving monomer 154 may be a different hydrogen bond donating monomer from at least one hydrogen bond donating monomer 152.

[0020] In some variations, at least one hydrogen bond donating monomer 152 (also referred to herein as “donor site 152”) is an acrylate monomer having one or more side groups including a free carbonyl (-C=O) group or a primary, secondary, or tertiary amine side group on the acrylate. And in at least one variation, at least one hydrogen bond receiving monomer 154 (also referred to herein as “receiving site 154”) is an acrylate monomer having one or more side groups including a free hydroxyl (-OH), a primary or secondary amine (-N(H)-, for example, urethane (C(O)-N(H)-)), or an imine (-N=). Furthermore, at least one rigid monomer 156 (also referred to herein as “rigid site 156”) may be an acrylate monomer having one or more side groups, including one or more of cyclohexyl, substituted cyclohexyl, and bicyclic side groups (in particular isobornyl, norbornyl, and dicyclopentanyl). In addition, the donor site 152 and / or receiving site 154 is an oligomer (e.g., a diacrylate based on an aliphatic urethane) that functions as a crosslinking agent.

[0021] Examples of at least one hydrogen bond-donating monomer 152 include, but are not limited to, 2-hydroxyethyl acrylate (2-HEA), caprolactone acrylate, hydroxypropyl acrylate, 2,3-dihydroxypropyl acrylate, 1,3-dihydroxypropyl acrylate, N-hydroxyethyl acrylamide, and diacrylates based on aliphatic urethanes. Examples of at least one hydrogen bond-receiving monomer 154 include, but are not limited to, aliphatic urethane-based diacrylate (AUD) and 2-HEA. And examples of at least one rigid monomer 156 include, but are not limited to, isobornyl acrylate (IOBA), 4-acryloylmorpholine, methyl methacrylate, 2-hydroxyethyl methacrylate, and isobornyl methacrylate.

[0022] In some modifications, the resin relating to the teachings of this disclosure (also referred to herein for brevity as "resin 150") contains about 5% by weight (wt) to about 35% by weight of at least one hydrogen bond donor monomer 152, and in at least one modification, resin 150 contains about 10% by weight to about 30% by weight of at least one hydrogen bond donor monomer 152. Furthermore, in some modifications, resin 150 contains about 15% by weight to about 25% by weight of at least one hydrogen bond donor monomer 152. For example, in at least one modification, resin 150 contains about 20% by weight of at least one hydrogen bond donor monomer 152.

[0023] In some variations, the resin 150 contains about 5% to about 35% by weight of at least one hydrogen bond receiving monomer 154, and in at least one variation, the resin 150 contains about 10% to about 30% by weight of at least one hydrogen bond receiving monomer 154. Furthermore, in some variations, the resin 150 contains about 15% to about 25% by weight of at least one hydrogen bond receiving monomer 154. For example, in at least one variation, the resin 150 contains about 20% by weight of at least one hydrogen bond receiving monomer 154.

[0024] In some variations, the resin 150 contains about 45% to about 75% by weight of at least one rigid monomer 156, and in at least one variation, the resin 150 contains about 50% to about 70% by weight of at least one rigid monomer 156. Furthermore, in some variations, the resin 150 contains about 55% to about 65% by weight of at least one rigid monomer 156. For example, in at least one variation, the resin 150 contains about 60% by weight of at least one rigid monomer 156.

[0025] In some variations, resin 150 contains a photoinitiator. For example, in some variations, the resin contains about 0.1% to about 2% by weight of the photoinitiator, for example, about 0.4% to 1.6% by weight of the photoinitiator, or about 0.7% to about 1.3% by weight of the photoinitiator. In at least one variation, resin 150 contains about 1.0% by weight of the photoinitiator. Examples of photoinitiators include, but are not limited to, photoinitiator 819 (phenylbis(2,4,6-trimethylbenzoyl) phosphate phosphine) and camphorquinone.

[0026] In some variations, resin 150 contains a light absorber. For example, in some variations, the resin contains about 0.01% to about 1% by weight of the light absorber, for example, about 0.025% to 0.5% by weight of the light absorber, or about 0.04% to about 0.1% by weight of the light absorber. In at least one variation, resin 150 contains about 0.05% by weight of the light absorber. Examples of light absorbers include, but are not limited to, methylene, coccine, and tartrazine. [Examples]

[0027] Without limiting the scope of this disclosure, in order to better illustrate the resin 150, its properties, and its potential for manufacturing monolithic structures with a wide range of properties, one exemplary composition of the resin 150, and many examples of monolithic structures and their corresponding properties are described below.

[0028] Resin 150 was prepared by mixing the monomers 2-hydroxyethyl acrylate (Sigma-Aldrich, MO, USA), isobornyl acrylate (Sigma-Aldrich), and AUD (Ebecryl 8413, Allnex, GA, USA) in a weight ratio of 20:60:20. Then, 1% by weight of a photoinitiator (Irgacure 819, Sigma-Aldrich) and 0.05% by weight of a light absorber (Sudan I, Sigma-Aldrich) were added to the monomer mixture.

[0029] While not bound by theory, IBOA and 2-HEA were included as linear builders, and AUD as a crosslinking agent. AUD is a viscous oligomer with high molecular weight aliphatic chains and urethane units that interacts with 2-HEA and IOBA monomers to form HN…O hydrogen bonds. Additionally, 2-HEA provides abundant -OH groups, which further form OH…O hydrogen bonds.

[0030] When the degree of hardening (also known as "degree of hardening" and referred to as "DoC" in this specification) is low, the covalent network and the abundant hydrogen bonds of the hardened resin result in a rubbery, highly extensible structure, as shown in Figure 2A. On the other hand, when the DoC is high, the hard IBOA has a glass transition temperature (T) above room temperature, as shown in Figure 2B. g This exhibits glass-like behavior, resulting in high elasticity.

[0031] Referring to Figures 3A and 3B, resin 150 was used in a bottom-up DLP printer that projected light from the bottom of a vat. This bottom-up DLP printer used a 385nm UV-LED light projector (PRO4500, Wintech Digital Systems Technology, Carlsbad, CA, USA) and a linear motion stage (LTS150, Thorlabs, Newton, NJ, USA). A container with an oxygen-permeable window (Teflon AF-2400, Biogeneral, CA, USA) was used as the resin vat.

[0032] The designed 3D structure was sliced ​​to obtain multiple image files with a thickness of 0.05 mm, which were then converted to grayscale image files using a MATLAB® script. The designed 3D structure was printed using a continuous liquid interface production (CLIP) approach at an optimal speed of 3 seconds per layer. Before printing, the printer's light intensity was calibrated using a photometer (ILT1400-A Radiometer, International Light Technologies, MA, USA).

[0033] Uniaxial tension tests were performed using a universal testing machine (Insight 10, MTS Systems, Eden Prairie, MN, USA) at a crosshead speed of 5 mm / min. Dynamic thermodynamic properties were investigated using a DMA machine (Q800, TA Instruments, New Castle, DE, USA) by changing the temperature at a rate of 10°C / min. The peak intensity of acrylate measured by normalized FTIR (Nicolet iS50 spectrophotometer, Thermo Fisher Scientific, Waltham, MA, USA) was 809 cm⁻¹. -1 The degree of hardening was investigated by utilizing the phenomenon observed in the sample. Multiple tests were performed for each sample to confirm reproducibility.

[0034] Referring to Figure 3A, the designed 3D snail structure was first sliced ​​to obtain multiple 2D images, which were then converted into multiple grayscale images using a MATLAB script (MathWorks, Natick, MA, USA). These grayscale images were projected from the bottom onto an ink vat window (+z direction, Figure 1) to initiate free radical polymerization of the resin, and by locally varying the UV intensity, different DoCs were obtained throughout the fabricated part, resulting in different mechanical properties. As shown in Figure 3B, the printed snail had a hard shell (at 100% light intensity) and a soft body (at 40% light intensity). The shell withstood a 1 kg weight without visible deformation, while the body (e.g., the neck) easily stretched (400%).

[0035] It should be understood that different material properties were determined by varying the grayscale level of UV projection from 0% (maximum intensity, indicated as G0) to 100% (darkest, indicated as G100). To analyze the correlation between depth-dependent DoC and light dose, the photopolymerization rate was investigated using the photopolymerization (PP) model disclosed by Vitale et al. ("Interfacial Profile and Propagation of Frontal Photopolymerization Waves," Macromolecules 2015, 48(1), 198-205). Based on a slice thickness of 50 μm, and using the theoretically predicted correlation between the PP model and experimental tests, a grayscale range from G0 to G70 (70% darkness) was used to ensure a fast print speed and good shape fidelity. At G0, the light intensity was 24.82 mW / cm². 2 The DoC was 96% (determined by FTIR measurement), and at G70, the light intensity was 0.85 mW / cm². 2 The DoC rate was 55%.

[0036] The mechanical properties of structures formed by printing resin 150 using a g-DLP 3D printer at different grayscale levels were evaluated by uniaxial tensile tests, and the thermodynamic properties were investigated. As shown in Figures 4A and 4B, the printed polymer gradually softened from G0 to G50, with a Young's modulus of 487 MPa at G0. Furthermore, this "hard state" (G0) exhibited excellent toughness, approximately 109 J / m². 3 Furthermore, when the fracture toughness was measured by tear testing, it was found to be 650-10000 J / m 2The range was as follows. Rubber states G60 and G70 (Figure 4B) with a conversion degree of approximately 50-60% had elasticity of 0.38 MPa and 0.1 MPa, respectively, and could be stretched up to an upper limit of approximately 450%. Because hydrogen bonds existed extensively between uncured monomers with a cross-linked network, the printed parts became a stable organogel state, exhibiting excellent elastic properties and resilience even after 10,000 fatigue cycles, and the strain was large, ranging from 200% to 300% (Figure 4C).

[0037] The rigid monomer IOBA increased the Tg at high DoC, making the network stiffer and resulting in different elasticity at different DoCs. Figure 5A shows Young's modulus and Tg at different grayscale levels. g This provides an overview, showing that the difference in Young's modulus between the hard G0 and the soft G70 exceeds 4800 times. Figure 5B also shows a comparison of Young's modulus and elongation of monolithic structures formed from resin 150 and DLP materials reported in the literature. As shown in Figure 5B, resin 150 exhibits a wide range of Young's moduli and greater elastic elongation than any of the known materials reported in the literature. Therefore, these experimental results indicate that high extensibility at low DoC can be achieved by using monomers that form a cured network chain through hydrogen bonding.

[0038] Referring to Figures 6A to 6C, it is shown that structures formed using resin 150 and printed with g-LPD 3D exhibit composite-like properties. In particular, Figures 6A to 6B show two printed monolithic composite structures: one in which vertically oriented rigid G0 fibers are embedded in a flexible G60 matrix, and the other in which horizontally oriented rigid G0 fibers are embedded in a flexible G60 matrix. The structure with the horizontally oriented rigid G0 fibers was so soft that it could not support its own weight (approximately 1g), and was stretched to more than twice its own length by a 200g weight. In contrast, the structure with the vertically oriented rigid G0 fibers supported the same 200g weight without any deformation being observed. Figure 6C also shows a prototype airless tire having a compressible G60 rubber-like outer periphery for shock absorption and a rigid G0 inner hub structure. This integrated structure allows the tire to deform when subjected to a vertical force (simulating ground undulation), and to return completely to its original state when the force is removed.

[0039] Referring to Figures 7A and 7B, a composite designed to mimic arterial tissue and its stress-strain behavior, which exhibits a J-shaped curve, are shown. Such a J-shaped curve may be important for the function of arterial tissue in controlling blood flow at low pressure (or mechanical load), dilating the arteries and increasing blood flow, but when the dilation exceeds a certain limit, the arterial tissue hardens and restricts flow. This behavior is due to the structure of arterial tissue, which mainly consists of a soft elastin matrix embedded with stiff, winding collagen fibers. When the degree of tissue elongation is small, the winding collagen fibers provide little deformation resistance (due to their curvature) until the tissue straightens out and then stretches axially with a large tissue elongation rate.

[0040] The composite structure shown in Figure 7A mimics the structure of arterial tissue by using resin 150 and g-DLP 3D printing to create a hollow cylindrical structure in which stiff G0 fibers are embedded in a soft elastic matrix of G60. In particular, schematic diagrams of cylindrical samples with straight stiff G0 fibers (indicated as T0), cylindrical samples with helical stiff G0 fibers with a first pitch (indicated as T2), and cylindrical samples with helical stiff G0 fibers with a second pitch greater than the first pitch (indicated as T10) are shown in Figure 7A. Composite samples of T0, T2, and T10, composite samples corresponding to pitches T6 and T8, and a sample with no fibers at all (indicated as M) were manufactured using resin 150 and a g-LPD 3D printer and subjected to uniaxial tensile testing. As shown in Figure 7B, the T8 and T10 structures exhibited J-shaped behavior, meaning that the stiffness, initially low, gradually increased to high, corresponding to the straightening of stiffer fibers. By adjusting the fiber pitch size (equivalent to the bend), the strain range was adjusted to match the straightening of the fibers, and the T10 structure exhibited the most pronounced J-shaped behavior. Thus, these results demonstrate that g-DLP 3D printing using resin 150 can be used for phototypes of artificial tissues that mimic the behavior of actual tissues.

[0041] Referring to Figures 8A and 8B, it is shown that a continuous deformation response was achieved by increasing the force level while subjecting resin 150 to g-DLP 3D printing using multiple grayscale levels. In particular, the sample shown in Figure 8A had spring-shaped rigid fibers (G0) embedded in a rubbery matrix with three compartments. The bottom compartment of the sample had a G66 matrix, the middle compartment had a G56 matrix, and the top compartment had a G46 matrix. As can be observed from the images of the three samples in Figure 8A, a clear time delay was observed in the deformation of each compartment, with the top G46 compartment being the stiffest and showing deformation at a relatively later stage. Figure 8B shows the overall strain change of the entire structure as a function of load.

[0042] Referring to Figure 9, the biometric structure of an artificial human heart valve having a soft and rigid portion, fabricated using resin 150 with a g-DLP 3D printer, is shown. This heart valve has a rigid support of G60 and three soft valve flaps of G60, and the valve moves between a closed and open position when the fluid flow state changes. The hydrodynamic performance of the g-DLP printed heart valve was tested using pressure loading on the inner surface of the flaps, and the experimental results were in good agreement with the results of FEA simulations. Therefore, resin 150 provides an efficient approach for creating patient-specific heart valve models for pre-operative planning.

[0043] Referring to Figure 10, a photograph is shown of a fish fin structure fabricated with a g-DLP printer using resin 150, in which rigid, bony fin rays of G0 are attached to a common G0 fin base and supported by a flexible tissue membrane of G60. Fish can change the shape of their fins by pushing and pulling the base to which the bony fin rays are attached using muscles and tendons, and the printed model shown in Figure 10 mimics this shape change. The movement of the fish fin was modeled using FEA, which induces opening and closing by applying pressure load perpendicular to the base, and the out-of-plane curvature of the membrane in the folded state and the in-plane curvature of the bony fin rays in the extended state closely matched experimental results. Therefore, resin 150 enables g-DLP 3D printing of fish fin structures, and because it can accurately reproduce such mechanisms, it facilitates the rapid fabrication of flexible robotic structures in biomimetics.

[0044] Referring to FIGS. 11A - 11B, a designed biomimetic structure having a complex multi - material composition is shown. In particular, nacreous structures, Bouligand structures, and bulk or simple structures manufactured using resin 150 with a g - DLP 3D printer are shown in FIG. 11B, and the load as a function of displacement in the fracture toughness tests of the three structures is shown in FIG. 11B. The nacreous structure and the Bouligand structure have hard flakes or fibers held or joined together, and there is a soft interface of G70 between them, which extends the crack propagation path and dissipates energy. By changing specific parameters of the structure such as flake / fiber size, aspect ratio, or the detailed arrangement of the two - phase, the toughness of the printed composite can be adjusted or optimized.

[0045] Referring particularly to FIG. 11B, the results of three - point bending of the printed biomimetic structure are shown. The nacreous structure has dimensions of 48 mm (L), 6 mm (W), 6 mm (t) and has 51% of the soft material of G70, and the Bouligand structure has dimensions of 56 mm (L), 6 mm (W), 6 mm (t) and has 48% of the soft material (G70). The three - point bending device has a span of 32 mm, and the fracture toughness of the nacreous structure and the Bouligand structure are 166 Kpa m 0.5 and 146 Kpa m 0.5 respectively. In comparison, the fracture toughness of the bulk - cured sample of G0 is 42 Kpa m 0.5 respectively. Therefore, the nacreous structure and the Bouligand structure exhibit a fracture toughness approximately 3 - 4 times greater than that of the G0 cured - bulk sample, and the g - DLP 3D printing of resin 150 shows performance suitable for the concept of testing various biomimetic structures.

[0046] Referring to Figures 12–15, g-DLP 3D printing of resin 150 for forming complex inflatable structures is shown. While inflatability is a desirable property in many applications, it often limits the design space due to the use of only one material, and complex inflating using multiple materials by 3D printing typically requires multiple material tanks or a combination of multiple printing techniques. Resin 150, on the other hand, allows for the addition of rigid inclusions anywhere within a soft, stretchable matrix using a single resin vat, thereby providing a wide range of inflatable designs that are not easily achievable with other techniques.

[0047] Referring to Figures 12A and 12B, Figure 12A shows photographs of an actual pufferfish before and after inflation, and Figure 12B shows a photograph of a biomimetic pufferfish manufactured using resin 150 with a g-DLP 3D printer. The black dotted line in Figure 12B represents the material switching region; the material above the dotted line is printed in G0 grayscale, and the material below the dotted line is printed in G60 grayscale. When an internal pressure of 30 kPa was applied to the inside of the biomimetic pufferfish, the rigid body part (upper part) of the biomimetic pufferfish swelled slightly, and the soft abdomen (lower part) of the biomimetic pufferfish swelled to about 10 times its initial volume, successfully mimicking the behavior of an actual pufferfish.

[0048] Referring to Figures 13A to 13D, photographs and FEA simulations are shown for four different membrane structures fabricated using resin 150 with a g-DLP 3D printer. Each design had a shallow, rigid cylinder with a rigid cap at the bottom and a soft membrane at the top. Figure 13A shows the soft membrane without any added rigid pattern, representing the default expansion state, which is typically the limit for an inflatable membrane made from a single material. Figure 13B shows a design in which one rigid ring is embedded within the soft membrane. Due to internal pressure, the soft material expands between the end of the cylinder and the outer diameter of the rigid ring, causing the rigid ring to lift. The rigid ring itself did not deform due to its relatively high elasticity. Inside the rigid ring was another compartment made of the soft membrane, which also lifted due to internal pressure. Figure 13C shows a design with four thin, rigid coaxial rings. These rigid rings prevented the soft film from expanding outward, but did not prevent it from expanding upward. This resulted in a relatively conical final shape, which differed significantly from the spherical shape of the simple soft film shown in Figure 13A. Figure 13D shows a design with four coaxial rigid 1 / 3 circles printed on a soft film. In Figure 13D, the left side of the soft film has rigid fibers, resulting in a generally linear shape, while the right side is free and spherical, resulting in an asymmetrical expansion. This inflation experiment closely matches the FEA simulation, and although only four designs are shown in Figures 13A-13D, it should be understood that other inflatable film processing can be easily achieved using resin 150.

[0049] Referring to Figures 14A to 14D, four different designs are shown in which rigid G0 fibers are embedded within an extensible, airtight cylindrical matrix of g60. These four designs can achieve four basic movements—expansion, twisting, contraction, and bending—by applying an internal pressure of 30 kPa. In a monolithic g-DLP 3D-printed soft actuator (using resin 150), the sequence and combination of these basic movements can result in advanced deformations. Figure 14A shows an expansion design in which rigid G0 rings are positioned along the length of a soft G60 tube. Without the rigid G0 rings, the soft G60 tube would likely deform primarily outward when expanded, but the thin rigid G0 rings prevent outward expansion. Furthermore, because these rigid G0 rings are not connected to each other, the actuator is very easily manipulated along its length, resulting in a significant length increase under pressure. Figure 14B shows an expansion design modification in which a rigid G0 ring is positioned along the length of a flexible G60 tube, allowing the actuator to be expanded. However, by adding a single rigid G0 fiber to one side of the flexible G60 tube, asymmetrical suppression was applied to the actuator, resulting in a bending motion.

[0050] Figure 14C presents a shrinkage design in which a stiff G0 fiber extends straight between two G0 end caps. Under pressure, the stiff G0 fiber bent outward but withstood the change in length. As a result, the curved stiff G0 fiber pulled the two G0 end caps closer together, as shown in the figure.

[0051] Figure 14D shows a torsional design with two helical rigid G0 rings (fibers) that spiral between the top and bottom of a soft G60 tube. Here too, the rigid G0 rings prevent the soft G60 tube from expanding radially outward, causing the helical structure to unwind and stretch vertically. As indicated by the arrows in the figure, the "unwinding" of the helical structure causes the torsional design actuator to twist. It should be understood that combining these actuator designs allows for use in complex applications such as soft robotics and biomimicry.

[0052] Referring to Figures 15A to 15D, tentacle-like actuators exhibiting curvature and twisting are shown. When the actuator shown in Figure 15A is inflated, it gradually coils up to form two circles, as designed and as shown in Figure 15B, thus mimicking the movement of a tentacle grasping an object. Figure 15C shows an actuator (weighing 5g) gripping a marker pen (weighing 8.5g), and Figure 15D shows an actuator gripping a 14g plastic centrifuge tube, thus functioning like an elephant's trunk. Compared to previous gripper designs, which typically required two or three fingers, actuators or grippers realized with resin 150 allow for or result in simpler designs. It should also be understood that the shape and movement of the inflated tentacles can be changed by easily altering the orientation and density of the fibers. The descriptions set forth above are merely illustrative and not intended to limit the disclosure or any use or application of the disclosure. The expression "at least one of A, B, and C" as used herein should be interpreted as meaning "A or B or C" using the non-exclusive logic "or". It should be understood that the principles of the disclosure remain unchanged even if the various steps included in a method are performed in a different order. The scope disclosure includes the disclosure of all individual scopes and individual subdivided scopes that are included in the overall scope.

[0053] The headings (e.g., “Background” and “Overview”) and subheadings used herein are intended solely to provide a general overview of the topics covered within the scope of this disclosure and are not intended to limit the disclosure of the technology or any aspect thereof. Descriptions of multiple forms or variations having the described features are not intended to exclude other forms or variations having further features or incorporating other combinations of the described features.

[0054] Where used herein, the terms “about” and “generally” in relation to numerical values ​​refer to the known variability or tolerance in commercial and / or experimental measurements of the quantities referred to. In some variations, such known commercial and / or experimental measurement tolerance is ±10% of the measured value; in other variations, such known commercial and / or experimental measurement tolerance is ±5% of the measured value; and in yet another variation, such known commercial and / or experimental measurement tolerance is ±2.5% of the measured value. And in at least one variation, such known commercial and / or experimental measurement tolerance is ±1% of the measured value.

[0055] The terms “equipped with” and “include” as used herein, and their variations thereof, are intended to be non-limiting, and the sequential listing or enumeration of items does not exclude other similar items that may be useful in the devices and methods of the Art. Similarly, the terms “may” and “may” and their variations are intended to be non-limiting, and any statement that a certain form or variation may include or be equipped with a particular element or feature does not exclude other forms or variations of the Art according to the present invention that do not include such element or feature.

[0056] The broad teachings of this disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes specific examples, the true scope of this disclosure should not be limited to the specific examples included herein, as other modifications will become apparent to those skilled in the art by studying the specification and the claims below. References to one or more embodiments within this specification mean that a specific feature, structure, or characteristic described in relation to a particular embodiment or modification is included in at least one embodiment or modification. Where the expression "in one modification" or "in one form" (or variations thereof) is used, this does not necessarily refer to the same embodiment or modification. Furthermore, it should be understood that the various method steps described herein do not necessarily have to be performed in the same order as described, and that each method step is not necessarily required in each embodiment or modification.

[0057] The descriptions of the forms or variations set forth above are provided for illustrative and explanatory purposes only. They are not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular form or variation are not generally limited to that particular form or variation and, where appropriate, are interchangeable and can be used in selected forms or variations without specific notation or description. Furthermore, individual elements or features of a particular form or variation may be modified in various ways. Such modifications should not be considered deviations from the scope of the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

[0058] While specific forms or variations are described above, alternatives, modifications, changes, improvements, and substantial equivalents that are not currently foreseeable or unforeseeable can be conceived by the applicants or other persons skilled in the art. Accordingly, the claims at the time of filing and as amended are intended to encompass all such alternatives, modifications, changes, improvements, and substantial equivalents.

Claims

1. A donating site which is in the form of an acrylate monomer selected from at least one of 2-hydroxyethyl acrylate, caprolactone acrylate, hydroxypropyl acrylate, 2,3-dihydroxypropyl acrylate, 1,3-dihydroxypropyl acrylate, N-hydroxyethyl acrylamide, and diacrylate based on an aliphatic urethane, A receiving site different from the donating site, which is in the form of an acrylate monomer selected from at least one of aliphatic urethane-based diacrylate and 2-hydroxyethyl acrylate, A rigid moiety in the form of an acrylate monomer selected from at least one of isobornyl acrylate, 4-acryloylmorpholine, methyl methacrylate, 2-hydroxyethyl methacrylate, and isobornyl methacrylate, Photoinitiator and A resin containing a light absorber, The donated portion constitutes 10% to 30% by weight of the total composition of the resin. The receiving portion comprises 10% to 30% by weight of the total composition of the resin. The resin is configured to form a solid polymer having a Young's modulus in the range of 0.1 MPa to 100 MPa using grayscale digital light processing 3D printing.

2. The resin according to claim 1, wherein the rigid portion constitutes 50% to 70% by weight of the total composition of the resin.

3. A donor site in the form of an acrylate monomer selected from the group consisting of 2-hydroxyethyl acrylate, caprolactone acrylate, hydroxypropyl acrylate, 2,3-dihydroxypropyl acrylate, 1,3-dihydroxypropyl acrylate, N-hydroxyethyl acrylamide, and diacrylates based on aliphatic urethanes, A receiving site different from the donating site, which is in the form of an acrylate monomer selected from the group consisting of aliphatic urethane-based diacrylate and 2-hydroxyethyl acrylate, A rigid moiety in the form of an acrylate monomer selected from the group consisting of isobornyl acrylate, 4-acryloylmorpholine, methyl methacrylate, 2-hydroxyethyl methacrylate, and isobornyl methacrylate, Photoinitiator and A resin containing a light absorber, The donated portion constitutes 10% to 30% by weight of the total composition of the resin. The receiving portion comprises 10% to 30% by weight of the total composition of the resin. The rigid portion comprises 50% to 70% by weight of the total resin composition. The resin is configured to form a solid polymer having a Young's modulus in the range of 0.1 MPa to 200 MPa using grayscale digital light processing 3D printing.

4. The resin according to claim 1 or 3, wherein the acrylate monomer of the donating site is 2-hydroxyethyl acrylate.

5. The resin according to claim 1 or 3, wherein the acrylate monomer of the receiving portion is a diacrylate based on aliphatic urethane.

6. The resin according to claim 1 or 3, wherein the acrylate monomer of the rigid portion is isobornyl acrylate.

7. The resin according to claim 1 or 3, wherein the acrylate monomer of the donating site is 2-hydroxyethyl acrylate, and the acrylate monomer of the receiving site is a diacrylate based on aliphatic urethane.

8. The resin according to claim 1 or 3, wherein the acrylate monomer of the receiving portion is a diacrylate based on aliphatic urethane, and the acrylate monomer of the rigid portion is isobornyl acrylate.

9. The resin according to claim 1 or 3, wherein the acrylate monomer of the donating portion is 2-hydroxyethyl acrylate, and the acrylate monomer of the rigid portion is isobornyl acrylate.

10. The resin according to claim 1 or 3, wherein the acrylate monomer of the donating portion is 2-hydroxyethyl acrylate, the acrylate monomer of the receiving portion is a diacrylate based on aliphatic urethane, and the acrylate monomer of the rigid portion is isobornyl acrylate.

11. A donor site containing 2-hydroxyethyl acrylate, Receiving site containing diacrylate based on aliphatic urethane, A rigid part containing isobornyl acrylate, Photoinitiator and A resin containing a light absorber, The 2-hydroxyethyl acrylate is present in an amount of 15% to 25% by weight of the total composition of the resin. The aliphatic urethane-based diacrylate is present in an amount of 15% to 25% by weight of the total resin composition. The isobornyl acrylate makes up 55% to 65% by weight of the total composition of the resin. The resin is configured to form a solid polymer having a Young's modulus in the range of 0.1 MPa to 300 MPa using grayscale digital light processing 3D printing.

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