A front-end polymerizable 3D printing ink and a method for preparing hydrogel by front-end polymerization-3D printing

Abstract

The application discloses a front-end polymerization-3D printing method for preparing a hydrogel and a front-end polymerizable 3D printing ink, and relates to the technical field of functional polymer material preparation; the Carbomer 940 particle hydrogel and the ink composed of acrylamide and acrylic acid are prepared based on the jamming phase change; the printability of the ink is researched; the front-end polymerization is combined with the 3D printing technology; the gel precursor liquid and Carbomer 940 are used as main components of the 3D printing ink; the front-end polymerization method is adopted; the gel scaffold with a specific structure and morphology is printed; the direct ink writing (DIW) technology is coupled with the front-end polymerization reaction; a polymer three-dimensional model is rapidly prepared with minimum energy input; meanwhile, the front-end face is propagated forward along the moving track of the printing needle in the printing process; the high heat release of the polymerization reaction in-situ solidifies the ink into a polymer, thereby improving the self-supporting ability of the model.

Description

Technical Field

[0001] This invention relates to the field of functional polymer material preparation technology, specifically to a front-end polymerizable 3D printing ink and a method for preparing hydrogels by front-end polymerization-3D printing. Background Technology

[0002] In recent years, additive manufacturing technology, commonly known as 3D printing, has been able to rapidly convert digital designs into complex and high-precision 3D models. Among various additive manufacturing technologies, DIW (In-Situ Curing) technology has become the most versatile 3D printing technology. It can print almost any material as long as the ink exhibits suitable rheological behavior. However, after printing, appropriate post-processing (solvent evaporation, thermosetting, photocuring, immersion, etc.) is often required based on the material properties to obtain the final 3D molded component. This not only wastes materials but also consumes energy. Therefore, the development of in-situ curing technology has become an urgent need for DIW. Pre-polymerization is a novel free radical reaction mode that transforms gel monomers into gels by the movement of local reaction regions within the gel monomers. With the heat source removed, the heat generated by the polymerization reaction itself diffuses to the unreacted areas, continuing to initiate polymerization until the monomers in the container are completely polymerized. This method is simple to operate, requires no stirring during polymerization, and is energy-saving and time-saving, making it an ideal polymerization method. Recently, pre-polymerization has been successfully combined with 3D printing for the rapid manufacture of thermosetting polymers. Importantly, once pre-polymerization is initiated, no additional energy is required within the system. Compared with traditional curing, the front-end polymerization curing strategy reduces energy requirements by more than ten orders of magnitude, greatly improving the manufacturing efficiency of high-performance polymers and their composites.

[0003] Existing general 3D printing technologies often require post-processing based on material properties after printing to obtain the final three-dimensional molded component. This not only wastes materials but also consumes energy. To address these issues, the inventors propose a front-end polymerization-3D printing method for preparing hydrogels. Summary of the Invention

[0004] To address the issue that existing 3D printing technologies often require post-processing based on material properties after printing to obtain the final three-dimensional component, which is both wasteful of materials and energy-intensive, this invention aims to provide a front-end polymerizable 3D printing ink and a method for preparing hydrogels via front-end polymerization-3D printing. This method offers advantages such as high speed, high efficiency, low energy consumption, and rapid molding, providing a pathway for the rapid and continuous preparation of hydrogels, and has high application value in both biological and chemical engineering fields.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a front-end polymerizable 3D printing ink and a method for preparing hydrogels by front-end polymerization-3D printing, the specific steps of which are as follows:

[0006] S1. Weigh a certain amount of acrylamide monomer, acrylic acid monomer and solvent dimethyl sulfoxide and put them into a container, and stir at room temperature until the solution is clear and transparent;

[0007] S2. Weigh a certain amount of rheology modifier Carbomer 940 and slowly add it to a beaker in several batches. Stir vigorously at room temperature until the solution is clear and transparent.

[0008] S3. Dissolve the crosslinking agent, polymerization inhibitor and initiator in the above mixed solution, and remove the air bubbles after thorough stirring to dissolve;

[0009] S4. Transfer the prepared printing ink to the syringe and fix it to the micro-injection pump. Connect it with a transparent tubing and needle, set the flow rate of the micro-injection pump, import and start the 3D printer printing program.

[0010] S5. After the ink is squeezed out and falls onto the printing platform, use a hot air gun to heat the ink. When the monomers in the ink begin to polymerize due to heat, remove the heat source. The end face moves forward along the printing direction at a constant speed, and finally achieves in-situ solidification of ink layer by layer.

[0011] S6, the ink contains Carbomer 940 particulate hydrogel and acrylamide, acrylic acid, and has printable and polymerizable characteristics;

[0012] Preferably, the syringe has an inner diameter of 18-20 mm, and the long needle has an inner diameter of 0.5-1.5 mm.

[0013] Preferably, the flow rate of the micro-injection pump is 1-3 mL / h, and the acrylamide monomer is acrylamide with a specific gravity of 6.8-40 wt%.

[0014] Preferably, the organic solvent is one of dimethyl sulfoxide and ethylene glycol, with a specific gravity of 25-55 wt%.

[0015] Preferably, the crosslinking agent is N,N'-methylenebisacrylamide, with a specific gravity of 0.14-0.7 wt%.

[0016] Preferably, the specific gravity of Carbomer 940 is 2-3.5 wt%.

[0017] Preferably, the initiator is ammonium persulfate with a specific gravity of 0.9-3 wt%.

[0018] Preferably, the polymerization inhibitor is 2,2,6,6 tetramethyl-1-piperidinoxy, with a specific gravity of 0.05-0.07 wt%.

[0019] Preferably, the printing speed of the 3D printer is 80-100 mm / min.

[0020] Preferably, the polymerization reaction is a front-end polymerization reaction method in which the soldering iron is used to initiate polymerization at a temperature of 80-120°C, the soldering iron is 0.8-1.2 mm away from the liquid surface, and the polymerization time is 20-40 s.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. In this invention, based on the front-end polymerization autocatalytic exothermic effect, the reaction rate is improved through the autocatalytic effect, thereby shortening the curing time and improving production efficiency. The exothermic effect can help regulate the reaction temperature, promote the polymerization of materials at a suitable temperature, prevent the material performance from deteriorating due to excessive temperature, and make the polymerization process more uniform, reduce the performance difference between batches, and ensure the consistency and reliability of the product.

[0023] 2. In this invention, front-end polymerization and 3D printing are combined to achieve in-situ curing of ink during the printing process. The in-situ curing technology can quickly solidify the printed layers, reduce flow and deformation, thereby improving the printing accuracy and detail. The degree of curing of the printed ink is 82.33%~87.82%, which has excellent performance. This indicates that the method can provide technical reference for the preparation of hydrogel materials and has high promotion and application value. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some 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 schematic diagram illustrating the principle of hydrogel preparation using front-end polymerization-3D printing technology in Example 1. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0027] Example: Figure 1 As shown, this invention provides a front-end polymerizable 3D printing ink and a method for preparing hydrogels via front-end polymerization-3D printing. The ink matrix comprises Carbomer 940 particle hydrogel, acrylamide, and acrylic acid, and possesses printable and polymerizable characteristics. The specific steps are as follows:

[0028] S1. Weigh a certain amount of acrylamide monomer, acrylic acid monomer and solvent dimethyl sulfoxide and put them into a container, and stir at room temperature until the solution is clear and transparent;

[0029] S2. Weigh a certain amount of rheology modifier Carbomer 940 and slowly add it to a beaker in several batches. Stir vigorously at room temperature until the solution is clear and transparent.

[0030] S3. Dissolve the crosslinking agent, polymerization inhibitor and initiator in the above mixed solution, and remove the air bubbles after thorough stirring to dissolve;

[0031] S4. Transfer the prepared printing ink to the syringe and fix it to the micro-injection pump. Connect it with a transparent tubing and needle, set the flow rate of the micro-injection pump, import and start the 3D printer printing program.

[0032] S5. After the ink is squeezed out and falls onto the printing platform, use a hot air gun to heat the ink. When the monomers in the ink begin to polymerize due to heat, remove the heat source. The end face moves forward along the printing direction at a constant speed, and finally achieves in-situ solidification of ink layer by layer.

[0033] The syringe has an inner diameter of 18-20 mm, and the long needle has an inner diameter of 0.5-1.5 mm.

[0034] By adopting the above technical solution, the fluid flow rate can be precisely controlled by the syringe inner diameter of 18-20 mm and the long needle inner diameter of 0.5-1.5 mm. It is suitable for injections with different flow rate requirements. The appropriate inner diameter design can reduce pressure loss in the flow and ensure the stability of the fluid during delivery. Furthermore, the selection of the inner diameter can be adjusted according to the viscosity of the liquid to ensure that there is no blockage or backflow during injection.

[0035] The flow rate of the micro-injection pump is 1-3 mL / h, and the acrylamide monomer is acrylamide with a specific gravity of 6.8-40 wt%.

[0036] By adopting the above technical solution, acrylamide can be used as a monomer to form a polymer network through polymerization, which can be widely used in the preparation of materials such as hydrogels. Its concentration affects the mechanical strength, elasticity and transparency of the final polymer, making it suitable for specific application needs.

[0037] The organic solvent is one of dimethyl sulfoxide and ethylene glycol, with a specific gravity of 25-55 wt%.

[0038] By adopting the above technical solution, these two solvents have good dissolving ability and can effectively dissolve a variety of compounds, including polar and non-polar substances. In chemical reactions, as solvents, they can improve the reaction rate and selectivity, promote the interaction between reactants, and adjust the viscosity of the formulation by changing the ratio of solvents, thus affecting the flowability and coatability of the material.

[0039] The crosslinking agent is N,N'-methylenebisacrylamide, with a specific gravity of 0.14-0.7wt%.

[0040] By adopting the above technical solution, cross-linking is formed between polymer chains to enhance the mechanical strength and heat resistance of the material. The flexibility, rigidity and elasticity of the material can be adjusted according to the degree of cross-linking to meet specific application requirements. Cross-linked polymers usually exhibit better thermal stability and chemical stability, thus extending the service life of the material.

[0041] The specific gravity of Carbomer 940 is 2-3.5 wt%.

[0042] By adopting the above technical solution, using Carbomer 940 as a thickener and stabilizer, the viscosity of the liquid can be increased, making the formulation thicker, improving fluidity and coatability, effectively suspending solid particles, preventing sedimentation, maintaining the appearance and performance of the product, helping to stabilize oil-water emulsions, preventing separation, and improving product uniformity.

[0043] The initiator is ammonium persulfate, with a specific gravity of 0.9-3 wt%.

[0044] By adopting the above technical solution, ammonium persulfate can decompose under heating or specific conditions to generate free radicals, thereby initiating a polymerization reaction and forming polymer chains. By adjusting its concentration, the rate and reaction time of the polymerization reaction can be controlled, achieving precise adjustment of product performance. Furthermore, at appropriate temperatures, ammonium persulfate can quickly and effectively generate sufficient free radicals, improving reaction efficiency and shortening reaction time.

[0045] The polymerization inhibitor is 2,2,6,6-tetramethyl-1-piperidinoxy, with a specific gravity of 0.05-0.07 wt%.

[0046] By adopting the above technical solutions, unnecessary chain growth can be suppressed, which helps to improve the consistency and performance of the final product, reduce the defect rate, and provide long-term stability, preventing polymer degradation or performance decline caused by environmental factors.

[0047] The printing speed of a 3D printer is 80-100 mm / min.

[0048] By adopting the above technical solution, a moderate printing speed can shorten printing time and improve production efficiency while ensuring printing quality. This is especially important in mass production. Furthermore, an appropriate printing speed helps control the temperature distribution of the material, avoiding thermal runaway caused by printing too fast or uneven material cooling caused by printing too slow.

[0049] The polymerization reaction is a front-end polymerization reaction method. The polymerization temperature initiated by the soldering iron is 80-120℃, the distance between the soldering iron and the liquid surface is 0.8-1.2 mm, and the polymerization initiation time is 20-40 s.

[0050] By adopting the above technical solution, the polymerization reaction is carried out under suitable thermal conditions by using an initiation temperature of 80-120℃, which can accelerate the reaction rate and improve the polymerization efficiency. The distance between the soldering iron and the liquid surface is 0.8-1.2 mm, which can ensure uniform heat transfer, avoid overheating or uneven cooling, and promote a stable polymerization process.

[0051] Working principle: When it is necessary to verify a method for preparing hydrogels through front-end polymerization and 3D printing:

[0052] Example 1

[0053] Weigh 6 g of acrylamide, 3 g of acrylic acid, and 6 g of dimethyl sulfoxide solvent and add them to a 25 mL glass beaker. Stir at room temperature until the mixture is completely mixed. Then, weigh 0.5 g of rheology modifier Carbomer 940 and slowly add it to the beaker in several batches. Stir vigorously at room temperature until the solution is clear and transparent. Then, weigh 0.1 g of N,N'-methylenebisacrylamide, 0.15 g of ammonium persulfate, and 0.01 g of 2,2,6,6-tetramethyl-1-piperidinoxy. After dissolving them completely, remove the air bubbles to obtain the front-end polymerization-3D printing ink. Start the 3D printer's printing program, transfer the prepared printing ink to the syringe and inject it. Then, use a micro-injection pump to expel the ink onto the printing platform at a flow rate of 2.3 mL / h. After heating the ink to a distance of 1.2 mm, use a soldering iron to initiate the polymerization for 10 seconds at an initiation temperature of 120°C. Once the monomers in the ink begin to polymerize, the polymer front moves at a constant speed along the printing direction. The polymerization front temperature is 113°C, and the front speed is 8.2 cm / min. After all the monomers have polymerized, a gel is obtained.

[0054] Example 2

[0055] Weigh 1 g of acrylamide, 3 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propionic acid)ammonium hydroxide, 6 g of dimethyl sulfoxide solvent, and 4 g of ethylene glycol solvent and add them to a 25 mL glass beaker. Stir at room temperature until the mixture is completely mixed. Then weigh 0.3 g of rheology modifier carbomer 940 and slowly add it to the beaker in several batches. Stir vigorously at room temperature until the solution is clear and transparent. Then weigh 0.1 g of N,N'-methylenebisacrylamide, 0.2 g of ammonium persulfate, and 0.01 g of 2,2,6,6-tetramethyl-1-piperidinoxy. After dissolving them completely, remove the air bubbles to obtain the front-end polymerization-3D printing ink. Start the 3D printer printing program, transfer the prepared printing ink to the syringe and introduce it, then use a micro-injection pump to squeeze the ink onto the printing platform at a flow rate of 2.3 mL / h. After heating with a soldering iron for 10 seconds at a distance of 1.2 mm from the ink, the ink will be ignited at a temperature of 120°C. Once the monomers in the ink begin to polymerize due to heat, the end face will move along the printing direction at a constant speed. After all the monomers have polymerized, a gel can be obtained.

[0056] Example 3

[0057] Weigh 4.0075 g of acrylamide, 0.8155 g of maleic anhydride-modified β-cyclodextrin, 0.9 g of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propionic acid)ammonium hydroxide, and 7.7 g of solvent ethylene glycol and add them to a 25 mL glass beaker. Stir at room temperature until the mixture is completely mixed. Then weigh 0.5 g of rheology modifier carbomer 940 and slowly add it to the beaker in several batches. Stir vigorously at room temperature until the solution is clear and transparent. Then weigh 0.021 g of N,N'-methylenebisacrylamide, 0.42 g of ammonium persulfate, and 0.0077 g of 2,2,6,6-tetramethyl-1-piperidinoxy. After dissolving them completely, remove the air bubbles to obtain the front-end polymerization-3D printing ink. Start the 3D printer printing program, transfer the prepared printing ink to the syringe and introduce it, then use a micro-injection pump to squeeze the ink onto the printing platform at a flow rate of 2.3 mL / h. After heating with a soldering iron for 10 seconds at a distance of 1.2 mm from the ink, the ink will be ignited at a temperature of 120°C. Once the monomers in the ink begin to polymerize due to heat, the end face will move along the printing direction at a constant speed. After all the monomers have polymerized, a gel can be obtained.

[0058] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing hydrogels via front-end polymerization and 3D printing, comprising the following specific steps: S1. Weigh a certain amount of acrylamide monomer, acrylic acid monomer and organic solvent and put them into a container. Stir at room temperature until the solution is clear and transparent. S2. Weigh a certain amount of rheology modifier Carbomer 940 and slowly add it to a beaker in several batches. Stir vigorously at room temperature until the solution is clear and transparent. S3. Dissolve the crosslinking agent, polymerization inhibitor and initiator in the above mixed solution, and remove the air bubbles after thorough stirring to dissolve; S4. Transfer the prepared printing ink to the syringe and fix it to the micro-injection pump. Connect it with a transparent tubing and needle, set the flow rate of the micro-injection pump, import and start the 3D printer printing program. S5. After the ink is squeezed out and falls onto the printing platform, use a hot air gun to heat the ink. When the monomers in the ink begin to polymerize due to heat, remove the heat source. The end face moves forward along the printing direction at a constant speed, and finally achieves in-situ solidification of ink layer by layer. The ink contains carbomer 940, acrylamide, and acrylic acid, and features printability and polymerizability.

2. The method for preparing hydrogels via front-end polymerization-3D printing as described in claim 1, characterized in that, The syringe has an inner diameter of 18-20 mm, and the needle has an inner diameter of 0.5-1.5 mm.

3. The method for preparing hydrogels via front-end polymerization-3D printing as described in claim 1, characterized in that, The flow rate of the micro-injection pump is 1-3 mL / h, and the acrylamide monomer is acrylamide with a specific gravity of 6.8-40 wt%.

4. The method for preparing hydrogels via front-end polymerization-3D printing as described in claim 1, characterized in that, The organic solvent is one of dimethyl sulfoxide and ethylene glycol, with a specific gravity of 25-55 wt%.

5. The method for preparing hydrogels via front-end polymerization-3D printing as described in claim 1, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide, with a specific gravity of 0.14-0.7 wt%.

6. The method for preparing hydrogels via front-end polymerization-3D printing as described in claim 1, characterized in that, The specific gravity of Carbomer 940 is 2-3.5 wt%.

7. The method for preparing hydrogels via front-end polymerization-3D printing as described in claim 1, characterized in that, The initiator is ammonium persulfate, with a specific gravity of 0.9-3 wt%.

8. The method for preparing hydrogels via front-end polymerization-3D printing as described in claim 1, characterized in that, The polymerization inhibitor is 2,2,6,6-tetramethyl-1-piperidinoxy, with a specific gravity of 0.05-0.07 wt%.

9. The method for preparing hydrogels via front-end polymerization-3D printing as described in claim 1, characterized in that, The printing speed of a 3D printer is 80-100 mm / min.

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