Front-end polymerization type 3D printing ink and method for preparing hydrogel through front-end polymerization-3D printing

Abstract

The invention discloses a method for preparing hydrogel through front-end polymerization-3D printing and front-end polymerization type 3D printing ink, and relates to the technical field of functional polymer material preparation. Ink formed by combining Carbomer 940 particle hydrogel, acrylamide and acrylic acid is prepared on the basis of blocking phase change, the printability of the ink is studied, front-end polymerization and a 3D printing technology are combined, a gel precursor solution and Carbomer 940 serve as main components of the 3D printing ink, a front-end polymerization method is adopted, a gel support of a specific structure and morphology is printed, and the 3D printing ink has the advantages of being simple in preparation process, low in cost and high in practicability. A direct ink writing (DIW) technology is coupled with a front-end polymerization reaction, a polymer three-dimensional model is rapidly prepared with minimum energy input, meanwhile, the front-end end face is spread forwards along with the moving track of a printing needle in the printing process, ink is cured into a polymer in situ through high heat release of the polymerization reaction, and the self-supporting capacity of the model is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of functional polymer material preparation, in particular to a front-end polymerizable 3D printing ink and a method for preparing a hydrogel by front-end polymerization-3D printing. Background Art

[0002] In recent years, additive manufacturing technology, commonly known as three-dimensional (3D) printing, has been able to quickly convert digital designs into complex and high-precision 3D models. Among various additive manufacturing technologies, DIW technology has become the most versatile 3D printing technology. As long as the ink exhibits appropriate rheological behavior, it can print almost any material. However, after printing, corresponding post-treatment (solvent evaporation, thermal curing, light curing, immersion, etc.) is often required according to the material properties to obtain the final three-dimensional 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. Front-end polymerization is a new free radical reaction mode that converts gel monomers into gel by moving local reaction areas in gel monomers. The heat source is evacuated, and the heat generated by the polymerization reaction itself diffuses to the unreacted area, continuing to initiate polymerization until the monomers in the container are completely polymerized. This method is simple to operate, does not require stirring during polymerization, and is energy-saving and time-saving. It is an ideal polymerization method. Recently, front-end polymerization has been successfully combined with 3D printing for rapid manufacturing of thermosetting polymers. Importantly, after the front-end polymerization is initiated, no additional energy is required in the system. Compared with traditional curing, the front-end polymerization curing strategy reduces the energy demand by more than ten orders of magnitude, greatly improving the manufacturing efficiency of high-performance polymers and their composites.

[0003] After printing, the existing general 3D printing technology often requires corresponding post-processing based on the material properties to obtain the final three-dimensional molded component. This not only wastes materials but also consumes energy. To address the above problems, the inventors proposed a method for preparing hydrogels by front-end polymerization-3D printing to solve the above problems. Summary of the invention

[0004] In order to solve the problem that the existing general 3D printing technology often needs to perform corresponding post-processing according to the material properties after printing to obtain the final three-dimensional molded component, which not only wastes materials but also consumes energy; the purpose of the present invention is to provide a front-end polymerizable 3D printing ink and a front-end polymerization-3D printing method for preparing hydrogels; this method has the advantages of fast speed, high efficiency, low energy consumption, fast molding, etc., provides a path for realizing the rapid and continuous preparation of hydrogels, and has high application value in the fields of biology and chemical engineering.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: a method for preparing hydrogel by front-end polymerization-3D printing ink and front-end polymerization-3D printing, wherein the specific steps are as follows: S1. Weigh a certain amount of acrylamide monomer, acrylic acid monomer and solvent dimethyl sulfoxide into a container, and stir at room temperature until the solution is clear and transparent; S2. Weigh a certain amount of polymerization inhibitor Carbomer 940 and slowly add it to the beaker several times, and stir vigorously at room temperature until the solution is clear and transparent; S3, dissolving the crosslinking agent, polymerization inhibitor and initiator in the above mixed solution, and removing bubbles after sufficient stirring and dissolution; S4, transfer the prepared printing ink into a syringe, fix it on a micro-injection pump, connect it with a transparent hose and a needle, set the flow rate of the micro-injection pump, and import and start the 3D printer printing program; S5. After the ink is squeezed out and falls on the printing platform, a hot air gun is used to heat the ink. When the monomers in the ink begin to polymerize due to the heat, the heat source is removed and the end face moves forward along the printing direction at a constant speed, and finally the ink is accumulated layer by layer and solidified in situ; S6, ink contains Carbomer940 particle hydrogel and acrylamide, acrylic acid, with printable and polymerizable characteristics; Preferably, the inner diameter of the syringe is 18-20 mm, and the inner diameter of the long needle is 0.5-1.5 mm.

[0006] Preferably, the flow rate of the microfluidic injection pump is 1-3 mL / h, and the acrylamide monomer is acrylamide, and its specific gravity is 6.8-40wt%.

[0007] Preferably, the organic solvent is one of dimethyl sulfoxide and ethylene glycol, and its specific gravity is 25-55wt%.

[0008] Preferably, the cross-linking agent is N,N'-methylenebisacrylamide, and its specific gravity is 0.14-0.7wt%.

[0009] Preferably, the specific gravity of Carbomer 940 is 2-3.5wt%.

[0010] Preferably, the initiator is ammonium persulfide, and its specific gravity is 0.9-3wt%.

[0011] Preferably, the polymerization inhibitor is 2,2,6,6-tetramethyl-1-piperidinyloxy, and its specific gravity is 0.05-0.07wt%.

[0012] Preferably, the printing speed of the 3D printer is 80-100 mm / min.

[0013] Preferably, the polymerization reaction is a front-end polymerization reaction method, the soldering iron used to initiate the polymerization temperature is 80-120° C., the soldering iron is 0.8-1.2 mm away from the liquid surface, and the soldering iron initiates the polymerization time 20-40 s.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, based on the self-catalytic exothermic effect of the front-end polymerization, the reaction rate is improved through the self-catalytic effect, thereby shortening the curing time and improving the production efficiency. The exothermic effect can help regulate the reaction temperature, promote the completion of polymerization of the material at a suitable temperature, and prevent the degradation of material performance due to excessively high temperature. In addition, the self-catalytic reaction can make the polymerization process more uniform, reduce the performance difference between batches, and ensure the consistency and reliability of the product.

[0015] 2. In the present 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 layer, reduce flow and deformation, thereby improving the printing accuracy and detail performance, and the printed ink curing degree is 82.33%~87.82%, which has excellent performance, indicating that this method can provide a technical reference for the preparation of hydrogel materials and has a high promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 Schematic diagram of the principle of preparing hydrogel using front-end polymerization-3D printing technology in Example 1. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example: Figure 1As shown, the present invention provides a front-end polymerizable 3D printing ink and a method for preparing hydrogel by front-end polymerization-3D printing. The main body of the ink contains Carbomer940 particle hydrogel, acrylamide, and acrylic acid, and has printability and polymerizability characteristics. The specific steps are: S1. Weigh a certain amount of acrylamide monomer, acrylic acid monomer and solvent dimethyl sulfoxide into a container, and stir at room temperature until the solution is clear and transparent; S2. Weigh a certain amount of polymerization inhibitor Carbomer 940 and slowly add it to the beaker several times, and stir vigorously at room temperature until the solution is clear and transparent; S3, dissolving the crosslinking agent, polymerization inhibitor and initiator in the above mixed solution, and removing bubbles after sufficient stirring and dissolution; S4, transfer the prepared printing ink into a syringe, fix it on a micro-injection pump, connect it with a transparent hose and a needle, set the flow rate of the micro-injection pump, and import and start the 3D printer printing program; S5. After the ink is squeezed out and falls on the printing platform, a hot air gun is used to heat the ink. When the monomers in the ink begin to polymerize due to the heat, the heat source is removed and the end face moves forward along the printing direction at a constant speed, and finally the ink is accumulated layer by layer and solidified in situ; S6, ink contains Carbomer940 particle hydrogel and acrylamide, acrylic acid, with printable and polymerizable characteristics; The inner diameter of the syringe is 18-20 mm, and the inner diameter of the long needle is 0.5-1.5 mm.

[0020] By adopting the above technical solution, the flow rate of the fluid can be accurately controlled through the inner diameter of the syringe of 18-20 mm and the inner diameter of the long needle of 0.5-1.5 mm, which is suitable for injections with different flow rate requirements. The appropriate inner diameter design can reduce the pressure loss in the flow and ensure the stability of the fluid during the delivery process. The choice of the inner diameter can be adjusted according to the viscosity of the liquid to ensure that there will be no blockage or backflow during injection.

[0021] The flow rate of the microfluidic injection pump is 1-3 mL / h, and the acrylamide monomer is acrylamide, and its specific gravity is 6.8-40wt%.

[0022] By adopting the above technical solution and using acrylamide as a monomer, a polymer network can be formed through polymerization, which is widely used in the preparation of materials such as hydrogels. Its concentration affects the mechanical strength, elasticity and transparency of the final polymer and is suitable for specific application requirements.

[0023] The organic solvent is one of dimethyl sulfoxide and ethylene glycol, and its specific gravity is 25-55wt%.

[0024] 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 increase the reaction rate and selectivity and promote the interaction between reactants. By changing the proportion of solvents, the viscosity of the formula can be adjusted, affecting the fluidity and coating properties of the material.

[0025] The cross-linking agent is N,N'-methylenebisacrylamide, and its specific gravity is 0.14-0.7wt%.

[0026] By adopting the above technical solution, the mechanical strength and heat resistance of the material can be enhanced by forming cross-links between polymer chains. 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 show better thermal stability and chemical stability, extending the service life of the material.

[0027] The specific gravity of Carbomer 940 is 2-3.5wt%.

[0028] By adopting the above technical solution, using Carbomer 940 mainly as a thickener and stabilizer, the viscosity of the liquid can be increased, making the formula thicker, improving fluidity and coating properties, effectively suspending solid particles, preventing precipitation, maintaining the appearance and performance of the product, and helping to stabilize the oil-water emulsion, prevent stratification, and improve the uniformity of the product.

[0029] The initiator is ammonium persulfide, and its specific gravity is 0.9-3wt%.

[0030] By adopting the above technical solution, ammonium persulfide can decompose under heating or specific conditions to generate free radicals, thereby starting a polymerization reaction to form a polymer chain. By adjusting its concentration, the rate and reaction time of the polymerization reaction can be controlled to achieve precise adjustment of product performance. At an appropriate temperature, ammonium persulfide can quickly and effectively generate sufficient free radicals, thereby improving reaction efficiency and shortening reaction time.

[0031] The polymerization inhibitor is 2,2,6,6-tetramethyl-1-piperidinyloxy, and its specific gravity is 0.05-0.07wt%.

[0032] By adopting the above technical solutions, by inhibiting unnecessary chain growth, it helps to improve the consistency and performance of the final product, reduce the defect rate, and provide long-term stability to prevent polymer degradation or performance decline caused by environmental factors.

[0033] The printing speed of the 3D printer is 80-100 mm / min.

[0034] By adopting the above technical solution, a moderate printing speed can shorten the printing time and improve production efficiency while ensuring the printing quality, which is particularly important in mass production. In addition, a proper printing speed helps to control the temperature distribution of the material, avoiding thermal runaway caused by too fast a printing speed or uneven material cooling caused by too slow a printing speed.

[0035] The polymerization reaction is a front-end polymerization reaction method, the soldering iron initiation polymerization temperature used is 80-120°C, the soldering iron is 0.8-1.2 mm away from the liquid surface, and the soldering iron initiation polymerization time is 20-40 s.

[0036] By adopting the above technical solution, the initiation temperature of 80-120°C ensures that the polymerization reaction is carried out under suitable thermal conditions, which can accelerate the reaction rate and improve the polymerization efficiency. The soldering iron is 0.8-1.2 mm away from the liquid surface to ensure uniform heat transfer, avoid overheating or uneven cooling, and promote a stable polymerization process.

[0037] Working principle: When a front-end polymerization-3D printing method for preparing hydrogels needs to be verified: Embodiment 1 Weigh 6 g acrylamide, 3 g acrylic acid, and 6 g solvent dimethyl sulfoxide and add them together into a 25 mL glass beaker. Stir at room temperature. After the mixed solution is completely mixed, weigh 0.5 g rheological agent Carbomer 940 and slowly add it into the beaker several times. Stir vigorously at room temperature until the solution is clear and transparent. Then weigh 0.1 g N,N'-methylenebisacrylamide, 0.15 g ammonium persulfate and 0.01 g 2,2,6,6-tetramethyl-1-piperidinyloxy. After fully dissolving, remove the bubbles to obtain front-end polymerization-3D printing ink. Start the 3D printer printing program, transfer the prepared printing ink into the syringe and introduce it, then use the microfluidic syringe pump to squeeze the ink out at a flow rate of 2.3 mL / h and drop it on the printing platform. Use an electric soldering iron to heat and trigger it 10 seconds after 1.2 mm from the ink. The triggering temperature is 120°C. When the monomers in the ink are heated and begin to polymerize, the end face moves along the printing direction at a constant speed. The front temperature of the polymerization is 113°C and the front speed is 8.2 cm / min. After all the monomers have completed polymerization, gel can be obtained.

[0038] Embodiment 2 1 g acrylamide, 3 g [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide, 6 g solvent dimethyl sulfoxide and 4 g solvent ethylene glycol were weighed and added into a 25 mL glass beaker. The mixture was stirred at room temperature. After the mixed solution was completely mixed, 0.3 g rheological agent Carbomer 940 was weighed and slowly added into the beaker several times. The mixture was stirred vigorously at room temperature until the solution was clear and transparent. Then 0.1 g N,N'-methylenebisacrylamide, 0.2 g ammonium persulfate and 0.01 g 2,2,6,6-tetramethyl-1-piperidinyloxy were weighed. After being fully dissolved, bubbles were removed to obtain front-end polymerization-3D printing ink. Start the 3D printer printing program, transfer the prepared printing ink into the syringe and introduce it, then use a microfluidic syringe pump to squeeze the ink out at a flow rate of 2.3 mL / h and drop it onto the printing platform. Use an electric soldering iron to heat it 1.2 mm away from the ink and trigger it for 10 s. The trigger temperature is 120°C. When the monomers in the ink begin to polymerize due to the heat, the end face moves along the printing direction at a constant speed. After all the monomers have completed polymerization, a gel can be obtained.

[0039] Embodiment 3 4.0075 g acrylamide, 0.8155 g maleic anhydride-modified β-cyclodextrin, 0.9 g [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide, and 7.7 g solvent ethylene glycol were weighed and added into a 25 mL glass beaker. The mixture was stirred at room temperature. After the mixed solution was completely mixed, 0.5 g rheological agent Carbomer 940 was weighed and slowly added into the beaker several times. The mixture was stirred vigorously at room temperature until the solution was clear and transparent. Then 0.021 g N,N'-methylenebisacrylamide, 0.42 g ammonium persulfate and 0.0077 g 2,2,6,6-tetramethyl-1-piperidinyloxy were weighed. After being fully dissolved, bubbles were removed to obtain front-end polymerization-3D printing ink. Start the 3D printer printing program, transfer the prepared printing ink into the syringe and introduce it, then use a microfluidic syringe pump to squeeze the ink out at a flow rate of 2.3 mL / h and drop it onto the printing platform. Use an electric soldering iron to heat it 1.2 mm away from the ink and trigger it for 10 s. The trigger temperature is 120°C. When the monomers in the ink begin to polymerize due to the heat, the end face moves along the printing direction at a constant speed. After all the monomers have completed polymerization, a gel can be obtained.

[0040] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing hydrogel by front-end polymerization-3D printing, the specific steps of which are: S1. Weigh a certain amount of acrylamide monomer, acrylic acid monomer and solvent dimethyl sulfoxide into a container, and stir at room temperature until the solution is clear and transparent; S2. Weigh a certain amount of polymerization inhibitor Carbomer 940 and slowly add it to the beaker several times, and stir vigorously at room temperature until the solution is clear and transparent; S3, dissolving the crosslinking agent, polymerization inhibitor and initiator in the above mixed solution, and removing bubbles after sufficient stirring and dissolution; S4, transfer the prepared printing ink into a syringe, fix it on a micro-injection pump, connect it with a transparent hose and a needle, set the flow rate of the micro-injection pump, and import and start the 3D printer printing program; S5. After the ink is squeezed out and falls on the printing platform, a hot air gun is used to heat the ink. When the monomers in the ink begin to polymerize due to the heat, the heat source is removed and the end face moves forward along the printing direction at a constant speed, and finally the ink is accumulated layer by layer and solidified in situ; S6, ink contains Carbomer940 particle hydrogel and acrylamide, acrylic acid, with printable and polymerizable characteristics.

2. A method for preparing hydrogel by front-end polymerization-3D printing as claimed in claim 1, It is characterized in that The inner diameter of the syringe is 18-20 mm, and the inner diameter of the long needle is 0.5-1.5 mm.

3. A method for preparing hydrogel by front-end polymerization-3D printing as claimed in claim 1, It is characterized in that The flow rate of the microfluidic injection pump is 1-3 mL / h, and the acrylamide monomer is acrylamide, and its specific gravity is 6.8-40 wt%.

4. A method for preparing a hydrogel by front-end polymerization-3D printing as claimed in claim 1, It is characterized in that The organic solvent is one of dimethyl sulfoxide and ethylene glycol, and its specific gravity is 25-55wt%.

5. The method for preparing hydrogel by front-end polymerization-3D printing as claimed in claim 1, It is characterized in that The cross-linking agent is N,N'-methylenebisacrylamide, and its specific gravity is 0.14-0.7wt%.

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

7. The method for preparing hydrogel by front-end polymerization-3D printing as claimed in claim 1, It is characterized in that The initiator is ammonium persulfide, and its specific gravity is 0.9-3wt%.

8. The method for preparing hydrogel by front-end polymerization-3D printing as claimed in claim 1, It is characterized in that The polymerization inhibitor is 2,2,6,6-tetramethyl-1-piperidinyloxy, and its specific gravity is 0.05-0.07wt%.

9. The method for preparing hydrogel by front-end polymerization-3D printing as claimed in claim 1, It is characterized in that The printing speed of the 3D printer is 80-100mm / min.

10. The method for preparing hydrogel by front-end polymerization-3D printing according to claim 1, It is characterized in that The polymerization reaction is a front-end polymerization reaction method, the soldering iron used to initiate the polymerization temperature is 80-120° C., the soldering iron is 0.8-1.2 mm away from the liquid surface, and the soldering iron initiates the polymerization time is 20-40 s.

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