A method for preparing a 3D-printed double-layer magnetically responsive hydrogel
By in situ forming Fe3O4 magnetic particles in thermosensitive hydrogel and combining them with sodium magnesium lithium silicate cross-linking, a double-layer magnetically responsive hydrogel with high toughness and uniform structure was prepared, which solved the problems of poor mechanical properties and low 3D printing yield of magnetically responsive hydrogel, and achieved 4D deformation and high yield under magnetic field.
Patent Information
- Application Number
- CN202411854980.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-17
- Publication Date
- 2025-10-14
- Estimated Expiration
- 2044-12-17
AI Technical Summary
Existing magnetically responsive hydrogels have poor mechanical properties, uneven distribution of magnetic particles, and low 3D printing yield.
A double-layer magnetic responsive hydrogel preparation method was adopted. By in situ forming Fe3O4 magnetic particles in the thermosensitive hydrogel, combined with sodium magnesium lithium silicate cross-linking and 3D printing technology, a double-layer magnetic responsive hydrogel with high toughness and uniform structure was prepared.
A double-layer magnetically responsive hydrogel with high toughness and uniform structure was achieved, which is capable of 4D deformation under magnetic field conditions, improving the 3D printing yield and mechanical properties.
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Figure CN119684639B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a method for 3D printing of magnetic response hydrogel, and belongs to the technical field of 3D printing materials. BACKGROUND
[0002] Gel as a special dispersion system, the molecules in it are connected to form a network structure full of dispersion medium under certain conditions, due to its unique properties and internal structure, it has attracted more and more attention in the field of drug delivery, biomedical and other fields. Combining gel materials with other materials with unique properties, while retaining the characteristics of gel materials, new functions are given, such as temperature response hydrogel, magnetic hydrogel. Among them, the shape deformation of the existing temperature response hydrogel must be triggered in the liquid environment, which greatly limits their application, and the aggregation of magnetic particles in the hydrogel matrix is always a problem, and the distribution of magnetic particles will significantly affect the mechanical properties of magnetic response hydrogel, and the yield is low when using 3D printing, which limits their practical application. SUMMARY
[0003] The present application is to solve the technical problems of the existing magnetic response hydrogel, such as poor mechanical properties, uneven distribution of magnetic particles, and low yield of 3D printing, and to provide a preparation method of 3D printed double-layer magnetic response hydrogel. The preparation method of magnetic response hydrogel for 3D printing is simple, low in cost, and high in yield of double-layer hydrogel structure.
[0004] The preparation method of 3D printed double-layer magnetic response hydrogel of the present application is carried out in the following steps:
[0005] I. Take 0.1-1 parts of N,N'-methylene bisacrylamide, 0.1-1 parts of photoinitiator, 10-30 parts of water, 5-10 parts of sodium magnesium lithium silicate, 5-10 parts of recrystallized N-isopropyl acrylamide and 1-5 parts of dimethylaminopropyl methyl propionamide by weight ratio;
[0006] II. N,N'-methylene bisacrylamide and photoinitiator are added to water in turn, stirred for 5-15 min, and then sodium magnesium lithium silicate is added to the aqueous solution in batches under stirring, and the addition is completed within 10-30 seconds, and the stirring is continued until the mixed solution presents gel state; after the mixed solution presents gel state, recrystallized N-isopropyl acrylamide and dimethylaminopropyl methyl propionamide are added to the mixed solution under nitrogen protection and stirred for 2-3 h, and then transferred to a centrifuge to remove the gas bubbles in the gel solution, and a temperature sensitive deformation gel solution is obtained;
[0007] III. The temperature-sensitive deformed gel liquid is added to a 3D printer for 3D extrusion printing. After printing, the printing liquid maintains the printing shape by self-supporting effect, and a gel body is obtained. The gel body is transferred to an ultraviolet light curing lamp for light curing for 2-3 min, and a cured body is obtained. The cured body is transferred to room temperature deionized water for full swelling, and unreacted monomers are removed, and a temperature-sensitive hydrogel body is obtained.
[0008] IV. Iron chloride hexahydrate and ferrous chloride tetrahydrate are weighed and added to deionized water, and magnetic stirring is performed to fully dissolve the solid particles, and an iron salt aqueous solution is obtained. In the iron salt aqueous solution, the molar ratio of Fe 2+ to Fe 3+ is 1:1.
[0009] V. The temperature-sensitive hydrogel body after swelling is immersed in the iron salt aqueous solution for 36-48 h to fully swell the temperature-sensitive hydrogel body, and a swollen temperature-sensitive hydrogel body is obtained. In the iron salt aqueous solution, divalent iron ions Fe 2+ and trivalent iron ions Fe 3+ enter the gel polymer network gap through the diffusion of water molecules.
[0010] VI. The swollen temperature-sensitive hydrogel body is transferred to a NaOH solution for 20-24 h, and a magnetic responsive hydrogel body is obtained. In this process, the swollen temperature-sensitive hydrogel body will quickly turn black after contacting the NaOH solution, because the divalent and trivalent iron ions have been transferred to the gel network before contacting the sodium hydroxide solution. The hydroxyl group will form Fe3O4 magnetic particles in situ in the gel network during the migration of water molecules. After full absorption and reaction, Fe3O4 magnetic particles are formed in situ in the gel.
[0011] VII. The temperature-sensitive hydrogel body obtained in step III is bonded to the magnetic responsive hydrogel body obtained in step VI, and a 3D printed double-layer magnetic responsive hydrogel is prepared. The lower layer is a temperature-sensitive hydrogel, and the upper layer is a magnetic responsive hydrogel. The double-layer magnetic responsive hydrogel can undergo a 4D deformation process under the magnetic field generated by an electric current.
[0012] Further, the photoinitiator in step I is (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide (TPO).
[0013] Further, in step one, 0.5-1 parts of N,N'-methylenebisacrylamide, 0.2-0.5 parts of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, 10-30 parts of water, 5-10 parts of sodium magnesium lithium silicate, 5-10 parts of recrystallized N-isopropyl acrylamide, and 1-5 parts of dimethylaminopropyl methyl propionamide are weighed by weight fraction; the sodium magnesium lithium silicate is used as a rheological modifier, the N,N'-methylenebisacrylamide is used as a chemical crosslinking agent, and the N-isopropyl acrylamide and dimethylaminopropyl methyl propionamide are used as temperature-sensitive monomers to prepare a temperature-sensitive deformation gel liquid; the temperature-sensitive deformation gel 3D printing liquid synthesized under this condition exhibits better 3D printing forming stability and a product rate of 100%. Different contents of lithium magnesium silicate cause different flowabilities of the temperature-sensitive deformation gel 3D printing liquid; when the weight fraction of lithium magnesium silicate is less than 5 parts, the angle between the liquid surface and the container wall of the printing liquid precursor becomes smaller after being inclined and standing for ten minutes, because when the content of lithium magnesium silicate is low, the printing liquid precursor still has a certain autonomous flowability, and the shape retention is poor, which cannot be quickly shaped, causing the printing to be unable to be self-supporting and unable to realize accurate 3D printing. When the content of lithium magnesium silicate is 5-10 parts, the angle between the liquid surface and the container wall of the printing liquid precursor is still 90 degrees after being inclined and standing, and there is no obvious change after being inclined and standing for ten minutes, indicating that when the content of lithium magnesium silicate is 5-10 parts, the rapid forming and self-supporting can be realized. In addition, when the content of lithium magnesium silicate is greater than 10 parts, the printing liquid becomes more viscous, the flowability of the printing liquid becomes poor, and accurate printing and forming cannot be realized.
[0014] Further, in step two, the speed of the centrifuge is 6000 rpm, and the centrifugation time is 5 min to obtain the temperature-sensitive deformation gel 3D printing liquid.
[0015] Further, in step two, the preparation method of the recrystallized N-isopropyl acrylamide is as follows: 10 g of NIPAM is dissolved in toluene, and the solution is heated to 60°C in a magnetic stirring water bath at a stirring rate of 400 rpm until complete dissolution; 40 mL of n-hexane is added to the solution, and the solution is kept at 60°C and stirred for 20 min; toluene and n-hexane are added again, respectively, and the process is repeated twice; the mixed solution is filtered to remove the undissolved polymerization inhibitor, and the filtrate is kept in a refrigerator at -20°C for 12 h; the filtrate is filtered to obtain white flocculent crystals, and the crystals are freeze-dried to obtain 7 g of NIPAM crystals with a yield of 70%;
[0016] Further, the 3D extrusion printing in step three has the specific steps that: the built model is saved as an STL format file with a suffix, the model is imported into the RepetierHost software to adjust the printing position and size, the model is sliced, then the printer parameters are set, and then the 3D extrusion printing is carried out by using a double-head direct writing printer; the printer parameters are that the printing speed of the used extrusion 3D printing equipment is 10-30 mm / s, a Teflon needle with a diameter of 0.4-1.2 mm is used as the 3D printing needle, the printing needle height is set to be 0.7-1.2 mm, and the printing liquid extrusion speed is 10 mm / s.
[0017] Further, the solidified model in step three is transferred into room temperature deionized water for sufficient swelling by being soaked in the room temperature deionized water for 24 h.
[0018] Further, the wavelength of the ultraviolet light curing lamp in step three is 365 nm.
[0019] Further, the magnetic stirring in step four is carried out at a stirring speed of 500-800 rpm for 20-30 min.
[0020] Further, the concentration of the ferric chloride hexahydrate in the ferric salt aqueous solution in step four is 0.05-0.2 mol / L.
[0021] Further, the method for swelling the temperature-sensitive hydrogel model in step five is that: the temperature-sensitive hydrogel model is first soaked in room temperature deionized water for 40-48 h to remove unreacted impurities, and then is transferred into hot water at 80 DEG C for 1-2 h to shrink and swell.
[0022] Further, the concentration of the NaOH solution in step five is 1-5 mol / L; the mechanical properties of the magnetic hydrogel can be adjusted by changing the concentration of the alkaline solution.
[0023] Further, the bonding method in step seven is that: the volume ratio of the strong glue Loctite 406 to ethyl acetate is 1:10, the glue mixture is obtained by mixing uniformly, and then the temperature-sensitive hydrogel model and the magnetic responsive hydrogel model are bonded by the glue mixture to prepare the double-layer magnetic responsive hydrogel.
[0024] The present application improves the performance of the double-layer magnetic responsive hydrogel with high toughness and uniform structure which can be used for 3D printing and 4D printing from the following aspects.
[0025] (1) The high-toughness and structure-uniform double-layer magnetic responsive hydrogel for 3D printing of the application, wherein the poly(N-isopropyl acrylamide) hydrogel matrix is cross-linked by sodium magnesium lithium silicate, and Fe3O4 magnetic particles are precipitated in situ on the hydrogel polymer network, and the high toughness of the magnetic responsive hydrogel is due to the phase separation of the hydrogel in a high-concentration alkaline solution. And the original liquid environment trigger type hydrogel becomes a magnetic responsive hydrogel, and this shape deformation method using a magnetic field opens up a new method for programming complex 3D structures of hydrogels, which can realize remote control and make the hydrogel structure away from the liquid environment.
[0026] (2) The application adopts extrusion type 3D printing to print temperature-sensitive hydrogel, and designs a double-layer composed of magnetic responsive hydrogel and temperature-sensitive hydrogel. The 2D structure double-layer can evolve into a 3D shape in an alternating magnetic field (AMF) controlled by a magnetic heating effect, which ensures the perfect realization of 4D printing.
[0027] (3) The DMAPMA composite hydrogel is prepared, wherein sodium magnesium lithium silicate is uniformly dispersed in the hydrogel matrix. The DMAPMA chain is cross-linked with sodium magnesium lithium silicate through non-covalent interaction, and the magnetic particles can be uniformly distributed in the hydrogel due to hydrogen bond or ionic or coordination interaction, and the flowability of the temperature-sensitive deformation gel 3D printing liquid is adjusted by the content of lithium magnesium silicate, so that precise printing and forming are realized.
[0028] The residual magnetization of the 3D printable high-toughness and structure-uniform magnetic responsive hydrogel of the application is 3.92-4.98 emu / g, the Young's modulus is 3.82-5.34 kPa, and the elongation at break is 230%-280%, which can be used in the field of functional hydrogel preparation. BRIEF DESCRIPTION OF DRAWINGS
[0029] Figure 1 is a schematic diagram of the synthesis process of the temperature-sensitive magnetic gel in Example 1, (a) temperature-sensitive gel printing; (b) iron ion solution immersion; (c) synthesis of magnetic gel;
[0030] Figure 2 is a cross-shaped magnetic responsive temperature-sensitive gel physical sample prepared in Example 1;
[0031] Figure 3 is a flower self-folding process diagram of the flower-shaped double-layer magnetic responsive hydrogel prepared in Example 1 in an alternating magnetic field;
[0032] Figure 4 is a magnetic demonstration diagram of the double-layer magnetic responsive hydrogel prepared in Example 1;
[0033] Figure 5 is an XRD spectrum of the double-layer magnetic responsive hydrogel prepared in Examples 1-3;
[0034] Figure 6 is a thermogravimetric analysis curve of the double-layer magnetic responsive hydrogel prepared in Examples 1-3;
[0035] Figure 7 is a hysteresis loop diagram of the double-layer magnetic responsive hydrogel prepared in Examples 1-3. DETAILED DESCRIPTION
[0036] The present application will be described in detail below by way of examples. If not otherwise specified, the raw materials used are commercially available.
[0037] Example 1: The preparation method of the double-layer magnetic responsive hydrogel in this example is carried out in the following steps:
[0038] I. Take 0.015 g of N,N'-methylene bisacrylamide, 0.015 g of a photoinitiator (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide, 10 mL of deionized water, 0.5 g of sodium magnesium lithium silicate, 0.8 g of recrystallized N-isopropyl acrylamide, and 0.2 g of dimethylaminopropyl methyl propionamide; wherein the preparation method of the recrystallized N-isopropyl acrylamide is as follows: take 10 g of N-isopropyl acrylamide (NIPAM) dissolved in toluene, heat to 60°C in a magnetic stirring water bath at a speed of 400 rpm until completely dissolved, add 40 mL of n-hexane to the solution, and keep stirring at 60°C for 20 min; add toluene and n-hexane again, respectively, and repeat twice; remove the undissolved polymerization inhibitor by suction filtration, and place the filtrate in a refrigerator at -20°C for 12 h; remove the filtrate by suction filtration to obtain white flocculent crystals, and freeze-dry to obtain 7 g of NIPAM crystals with a yield of 70%;
[0039] II. Add N,N'-methylene bisacrylamide and the photoinitiator (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide to deionized water in sequence, stir for 10 min, and then add sodium magnesium lithium silicate to the aqueous solution in batches under stirring, add all within 30 seconds, and continue stirring for 60 min, at which time the solution presents a gel state; after the solution presents a gel state, add recrystallized N-isopropyl acrylamide and dimethylaminopropyl methyl propionamide to the mixed solution under nitrogen protection, stir for 2 h, and then transfer to a centrifuge for centrifugal treatment at a speed of 6000 rpm for 5 min to remove bubbles in the gel solution, to obtain a temperature-sensitive deformation gel solution;
[0040] III. The built model is saved as a file with the suffix-stl format, and the model is imported into the RepetierHost software to adjust the appropriate printing position and size, and the model is sliced to process, and then the printer parameters are set; the printer parameters are: a Teflon needle with a diameter of 0.8 mm is used as a 3D printing needle, the printing needle height is set to 0.9 mm, and the printing liquid extrusion speed is 10 mm / s; the temperature-sensitive deformation gel liquid is added to the 3D printer, and then a double-head direct writing printer is used for 3D extrusion printing to obtain a gel body; the gel body maintains the printing shape by relying on its self-supporting effect; then the gel body is transferred to an ultraviolet light curing lamp for light curing for 2 min to obtain a cured body; then the cured body is transferred to room temperature deionized water for immersion for 48 h, so that the gel is fully swollen to remove unreacted monomers, and a temperature-sensitive hydrogel body is obtained;
[0041] IV. 4 g of iron chloride hexahydrate and 1.5 g of ferrous chloride tetrahydrate are weighed and added to 100 mL of deionized water, and a magnetic stirrer is used to stir at a stirring rate of 500 rpm for 20 min to completely dissolve the solid particles, to obtain an iron salt aqueous solution; wherein the molar ratio of Fe 2+ and Fe 3+ is 1:1;
[0042] V. The temperature-sensitive hydrogel body is first immersed in deionized water at room temperature for 48 h to remove unreacted impurities, and then transferred to 80°C hot water for 2 h for shrinkage and swelling; the temperature-sensitive hydrogel body after swelling is immersed in the iron salt aqueous solution for 36 h to fully swell the temperature-sensitive hydrogel body, to obtain a swollen temperature-sensitive hydrogel body; the divalent iron ion Fe 2+ and the trivalent iron ion Fe 3+ enter the gel polymer network gap through the diffusion of water molecules;
[0043] VI. The swollen temperature-sensitive hydrogel body is transferred to a NaOH solution with a concentration of 3 mol / L for 24 h to obtain a magnetic responsive hydrogel body; in this process, the swollen temperature-sensitive hydrogel body will quickly turn black after contacting the NaOH solution, which is because the divalent and trivalent iron ions have been transferred to the gel network before contacting the sodium hydroxide solution, and the hydroxyl ions will form Fe3O4 magnetic particles in situ in the gel network during the migration of water molecules; after sufficient absorption and reaction, Fe3O4 magnetic particles are formed in situ in the gel;
[0044] Seven, the strong glue Loctite 406 and ethyl acetate were mixed uniformly at a volume ratio of 1:10 to obtain a glue mixture; the temperature-sensitive hydrogel type body obtained in step three was taken as the lower layer, the magnetic responsive hydrogel type body obtained in step six was taken as the upper layer, and the glue mixture was coated between the upper and lower layers for bonding to prepare a 3D printed double-layer magnetic responsive hydrogel. The double-layer magnetic responsive hydrogel can undergo a 4D deformation process under the condition of a magnetic field generated by an electric current.
[0045] Figure 1 A schematic diagram of the process of obtaining the magnetic responsive hydrogel type body in step six from the temperature-sensitive hydrogel type body in step three and the swollen temperature-sensitive hydrogel type body in step five in Example 1; wherein a is the temperature-sensitive hydrogel type body in step three, b is the swollen temperature-sensitive hydrogel type body in step five, and c is the magnetic responsive hydrogel type body in step six.
[0046] Figure 2 A photograph of the cross-shaped double-layer magnetic responsive hydrogel sample prepared in step six of Example 1, a is a 3D printed temperature-sensitive hydrogel, b is a magnetic responsive hydrogel generated by in-situ precipitation, and c is a magnetic force test diagram of the magnetic responsive hydrogel, from which it can be seen that the magnetic responsive hydrogel can be lifted by a magnet.
[0047] Figure 3 is a petal-shaped double-layer magnetic responsive hydrogel sample of Example 1, which is placed in a coil, the coil is energized to form a magnetic field, and the petal-shaped double-layer magnetic responsive hydrogel sample deforms under the condition of the magnetic field as shown in Figure 3 , which requires 4.5 min for the entire deformation process, and the temperature-sensitive hydrogel type body in the lower layer can remain in a stable gel state without flowing under this condition.
[0048] Figure 4 is a magnetic demonstration diagram of the double-layer magnetic responsive hydrogel prepared in Example 1, from which Figure 4 it can be seen that the double-layer magnetic responsive hydrogel can be moved by an external magnetic field.
[0049] Example 2: The preparation method of the double-layer magnetic responsive hydrogel of this example is as follows:
[0050] I. 0.03 g of N,N'-methylenebisacrylamide, 0.03 g of a photoinitiator (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide, 10 mL of deionized water, 1 g of sodium magnesium lithium silicate, 0.7 g of recrystallized N-isopropyl acrylamide, and 0.3 g of dimethylaminopropyl methylpropionamide were weighed; wherein the preparation method of the recrystallized N-isopropyl acrylamide is the same as that of Example 1;
[0051] II. N,N'-methylenebisacrylamide and a photoinitiator (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide were sequentially added to deionized water, stirred for 10 min, and then sodium magnesium lithium silicate was added to the aqueous solution in batches under stirring, added completely within 30 seconds, and continued to stir for 60 min. At this time, the solution showed a gel state. After the solution showed a gel state, recrystallized N-isopropyl acrylamide and dimethylaminopropyl methylpropionamide were added to the mixed solution under nitrogen protection and stirred for 2 h, and then transferred to a centrifuge for centrifugal treatment at a speed of 6000 rpm for 5 min to remove bubbles in the gel solution, to obtain a temperature-sensitive deformation gel solution;
[0052] III. The built model was saved as a file with a suffix of-stl format, the model was imported into RepetierHost software to adjust the appropriate printing position and size, the model was sliced, and then the printer parameters were set. The printer parameters were as follows: a Teflon needle with a diameter of 0.8 mm was used as a 3D printing needle, the printing needle height was set to 1.1 mm, and the printing liquid extrusion speed was 20 mm / s. The temperature-sensitive deformation gel solution was added to the 3D printer, and then a double-head direct writing printer was used for 3D extrusion printing to obtain a gel model. The gel model relied on its own self-supporting effect to maintain the printing shape. Then the gel model was transferred to an ultraviolet light curing lamp for photocuring for 2 min to obtain a cured model. Then the cured model was transferred to room temperature deionized water for immersion for 48 h, so that the gel was fully swollen to remove unreacted monomers, to obtain a temperature-sensitive hydrogel model;
[0053] IV. 4 g of iron chloride hexahydrate and 1.5 g of ferrous chloride tetrahydrate were weighed and added to 100 mL of deionized water. The solid particles were completely dissolved by stirring at a stirring rate of 500 rpm for 20 min using a magnetic stirrer to obtain an iron salt aqueous solution. In the iron salt aqueous solution, the molar ratio of Fe 2+ to Fe 3+ was 1:1.
[0054] V. The temperature-sensitive hydrogel model was first immersed in room temperature deionized water for 48 h to remove unreacted impurities, and then transferred to 80°C hot water for 2 h for shrinkage and swelling. The temperature-sensitive hydrogel model after swelling was immersed in the iron salt aqueous solution for 36 h to fully swell the temperature-sensitive hydrogel model, to obtain a swollen temperature-sensitive hydrogel model. In the iron salt aqueous solution, the divalent iron ion Fe 2+ and the trivalent iron ion Fe 3+ entered the gel polymer network gap through the diffusion of water molecules.
[0055] Six, the swollen temperature-sensitive hydrogel type body is transferred into a NaOH solution with a concentration of 4 mol / L and kept for 24 h to obtain a magnetic responsive hydrogel type body; in this process, the swollen temperature-sensitive hydrogel type body will become black after being in contact with the NaOH solution, because the divalent and trivalent iron ions have been transferred into the gel network before being in contact with the sodium hydroxide solution, and the hydroxyl ions will form Fe3O4 magnetic particles in situ in the gel network during the migration of water molecules, and after sufficient absorption and reaction, Fe3O4 magnetic particles will be formed in situ in the gel;
[0056] Seven, the strong glue Loctite 406 is mixed with ethyl acetate at a volume ratio of 1:10 to obtain a glue mixture; the temperature-sensitive hydrogel type body obtained in step three is the lower layer, and the magnetic responsive hydrogel type body obtained in step six is the upper layer, and the glue mixture is coated between the upper and lower layers for bonding to prepare a 3D printed double-layer magnetic responsive hydrogel. The double-layer magnetic responsive hydrogel can undergo a 4D deformation process under the condition of a magnetic field generated by an electric current.
[0057] The double-layer magnetic responsive hydrogel prepared in Example 2 can deform under the condition of a magnetic field, and the entire deformation process takes 5 min. The temperature-sensitive hydrogel in the lower layer can remain in a gel stable state under this condition without flowing.
[0058] Example 3: The preparation method of the double-layer magnetic responsive hydrogel in this example is as follows:
[0059] One, 0.015 g of N,N'-methylene bisacrylamide, 0.015 g of a photoinitiator (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide, 10 mL of deionized water, 1 g of sodium magnesium lithium silicate, 0.7 g of recrystallized N-isopropyl acrylamide, and 0.3 g of dimethylaminopropyl methyl propionamide are weighed; wherein the preparation method of the recrystallized N-isopropyl acrylamide is the same as that of Example 1;
[0060] Two, N,N'-methylene bisacrylamide and the photoinitiator (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide are sequentially added to deionized water, stirred for 10 min, and then sodium magnesium lithium silicate is added to the aqueous solution in batches under stirring, added within 30 seconds, and continues to stir for 60 min, at which time the solution presents a gel state; after the solution presents a gel state, recrystallized N-isopropyl acrylamide and dimethylaminopropyl methyl propionamide are added to the mixed solution under nitrogen protection and stirred for 2 h, and then transferred to a centrifuge for centrifugal treatment at a speed of 6000 rpm for 5 min to remove bubbles in the gel solution, to obtain a temperature-sensitive deformation gel solution;
[0061] III. The built model is saved as a file with the suffix-stl format, and the model is imported into the RepetierHost software to adjust the appropriate printing position and size, and the model is sliced to process, and then the printer parameters are set; the printer parameters are: the printing speed is 20 mm / s, a Teflon needle with a diameter of 1.2 mm is used as a 3D printing needle, the printing needle height is set to 0.9 mm, and the printing liquid extrusion speed is 20 mm / s; the temperature-sensitive deformation gel liquid is added to the 3D printer, and then a double-head direct writing printer is used for 3D extrusion printing to obtain a gel body; the gel body maintains the printing shape by relying on its self-supporting effect; then the gel body is transferred to an ultraviolet light curing lamp for light curing for 2 min to obtain a cured body; then the cured body is transferred to room temperature deionized water for immersion for 48 h, so that the gel is fully swollen to remove unreacted monomers, and a temperature-sensitive hydrogel body is obtained;
[0062] IV. 3.5 g of iron chloride hexahydrate and 2 g of ferrous chloride tetrahydrate are weighed and added to 100 mL of deionized water, and a magnetic stirrer is used to stir at a stirring rate of 500 rpm for 20 min to completely dissolve the solid particles, to obtain an iron salt aqueous solution; wherein the Fe 2+ and Fe 3+ molar ratio is 1:1;
[0063] V. The temperature-sensitive hydrogel body is first immersed in deionized water at room temperature for 48 h to remove unreacted impurities, and then transferred to 80°C hot water for 2 h for shrinkage and swelling; the temperature-sensitive hydrogel body after swelling is immersed in the iron salt aqueous solution for 36 h to fully swell the temperature-sensitive hydrogel body, to obtain a swollen temperature-sensitive hydrogel body; the divalent iron ion Fe 2+ and the trivalent iron ion Fe 3+ enter the gel polymer network gap through the diffusion of water molecules;
[0064] VI. The swollen temperature-sensitive hydrogel body is transferred to a NaOH solution with a concentration of 5 mol / L for 24 h to obtain a magnetic responsive hydrogel body; in this process, the swollen temperature-sensitive hydrogel body will quickly turn black after contacting the NaOH solution, which is because the divalent and trivalent iron ions have been transferred to the gel network before contacting the sodium hydroxide solution, and the hydroxyl ions will form Fe3O4 magnetic particles in situ in the gel network during the migration of water molecules; after sufficient absorption and reaction, Fe3O4 magnetic particles are formed in situ in the gel;
[0065] Seven, the strong glue Loctite 406 and ethyl acetate were mixed uniformly at a volume ratio of 1:10 to obtain a glue mixture; the temperature-sensitive hydrogel type body obtained in step three was taken as the lower layer, the magnetic responsive hydrogel type body obtained in step six was taken as the upper layer, and the glue mixture was coated between the upper and lower layers for bonding to prepare a 3D printed double-layer magnetic responsive hydrogel. The double-layer magnetic responsive hydrogel can undergo a 4D deformation process under the condition of a magnetic field generated by an electric current.
[0066] The double-layer magnetic responsive hydrogel sample of the embodiment can deform under the condition of a magnetic field, and the entire deformation process requires 5.2 min. The temperature-sensitive hydrogel in the lower layer can remain in a gel stable state without fluidity under the condition.
[0067] The double-layer magnetic responsive hydrogel prepared in examples 1-3 was subjected to XRD testing, and the obtained XRD spectrum is shown in Figure 5 From Figure 5 It can be seen that the characteristic peaks in the spectrum match the peaks of Fe3O4, indicating that the double-layer magnetic responsive hydrogel contains Fe3O4 particles, and the sizes of the Fe3O4 particles in the double-layer magnetic responsive hydrogels prepared in examples 1-3 are not significantly different.
[0068] The double-layer magnetic responsive hydrogel prepared in examples 1-3 was subjected to thermal gravimetric analysis, and the obtained thermal gravimetric curve is shown in Figure 6 From Figure 6 It can be seen that during the thermal treatment process of the double-layer magnetic responsive hydrogel, water will vaporize as the temperature rises, and most of the polymer materials will be ablated, and the main residual is inorganic matter such as iron oxide. Among the double-layer magnetic responsive hydrogels prepared in examples 1-3, the residual weight of the double-layer magnetic responsive hydrogel of example 1 is the highest, indicating that it has the highest content of iron oxide. The basis of the magnetic responsive hydrogel is to contain magnetic Fe3O4, so the content of iron is the highest, and it should have the best magnetic response.
[0069] The double-layer magnetic responsive hydrogel prepared in examples 1-3 was subjected to magnetic hysteresis loop testing, and the obtained magnetic hysteresis loop diagram is shown in Figure 7 From Figure 7 It can be seen that the double-layer magnetic responsive hydrogels prepared in examples 1-3 all exhibit obvious superparamagnetic behavior, and the residual magnetization of the double-layer magnetic responsive hydrogel prepared in example 1 is the largest, being 4.98 emu / g. The residual magnetization of the double-layer magnetic responsive hydrogel prepared in example 2 is 4.14 emu / g, and the residual magnetization of the double-layer magnetic responsive hydrogel prepared in example 3 is 3.92 emu / g.
[0070] The double-layer magnetic responsive hydrogel prepared in examples 1-3 was subjected to mechanical property testing, and the obtained mechanical properties are shown in Table 1.
[0071] Table 1 Mechanical properties of the double-layer magnetic responsive hydrogels prepared in Examples 1-3
[0072] Sample Young's modulus (kPa) Elongation at break (%) Example 1 4.54 280 Example 2 5.34 260 Example 3 Example 4 3.82 230
[0073] Example 4: The preparation method of the double-layer magnetic responsive hydrogel in this example was carried out in the following steps:
[0074] I. 0.015 g of N,N'-methylenebisacrylamide, 0.015 g of a photoinitiator (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 10 mL of deionized water, 1.5 g of sodium magnesium lithium silicate, 0.8 g of recrystallized N-isopropyl acrylamide, and 0.2 g of dimethylaminopropyl methacrylamide were weighed; the preparation method of the recrystallized N-isopropyl acrylamide was the same as that in Example 1;
[0075] II. N,N'-methylenebisacrylamide and the photoinitiator (2,4,6-trimethylbenzoyl)diphenylphosphine oxide were sequentially added to the deionized water, and after stirring for 10 min, the sodium magnesium lithium silicate was added to the aqueous solution in batches under stirring, and was completely dissolved in 30 seconds, and stirring was continued for 60 min, at which time the solution showed a gel state; after the solution showed a gel state, the recrystallized N-isopropyl acrylamide and dimethylaminopropyl methacrylamide were added to the mixed solution under nitrogen protection and stirred for 2 h, and then transferred to a centrifuge for centrifugal treatment at a speed of 6000 rpm for 5 min to remove the gas bubbles in the gel liquid, to obtain a temperature-sensitive deformation gel liquid;
[0076] III. The built model was saved as a file with the suffix name-stl format, the model was imported into the RepetierHost software to adjust the appropriate printing position and size, the model was sliced, and then the printer parameters were set; the printer parameters were as follows: a Teflon needle with a diameter of 0.8 mm was used as the 3D printing needle, the printing needle height was set to 0.9 mm, and the printing liquid extrusion speed was 10 mm / s; the temperature-sensitive deformation gel liquid was added to the 3D printer, and then a double-head direct writing printer was used for 3D extrusion printing to obtain a gel model; the gel model relied on its own self-supporting effect to maintain the printing shape; the gel model was then transferred to an ultraviolet light curing lamp for photocuring for 2 min to obtain a cured model; the cured model was then transferred to room temperature deionized water for immersion for 48 h, so that the gel was fully swollen to remove the unreacted monomers, to obtain a temperature-sensitive hydrogel model;
[0077] IV. 4.0 g of ferric chloride hexahydrate and 1.5 g of ferrous chloride tetrahydrate were added to 100 mL of deionized water, and a magnetic stirrer was used to stir at a stirring rate of 500 rpm for 20 min to completely dissolve the solid particles, to obtain an iron salt aqueous solution; the Fe 2+ and Fe 3+1:1 in molar ratio;
[0078] V. First, the temperature-sensitive hydrogel type body is fully immersed in deionized water at room temperature for 48 h to remove unreacted impurities, and then transferred to hot water at 80°C for 2 h for shrinkage and swelling. The temperature-sensitive hydrogel type body after swelling is immersed in an aqueous solution of iron salt ions for 36 h to fully swell the temperature-sensitive hydrogel type body, obtaining a swollen temperature-sensitive hydrogel type body; the aqueous solution of iron salt ions contains divalent iron ions Fe 2+ and trivalent iron ions Fe 3+ enter the gel polymer network interstices through the diffusion of water molecules;
[0079] VI. The swollen temperature-sensitive hydrogel type body is transferred to a NaOH solution with a concentration of 3 mol / L for 24 h, obtaining a magnetic responsive hydrogel type body; in this process, the swollen temperature-sensitive hydrogel type body will quickly turn black after contacting the NaOH solution, which is due to the fact that the divalent and trivalent iron ions have been transferred to the inside of the gel network before contacting the sodium hydroxide solution. The hydroxide ions will form Fe3O4 magnetic particles in situ in the gel network during the migration of water molecules. After sufficient absorption and reaction, Fe3O4 magnetic particles will be formed in situ in the gel;
[0080] VII. The glue mixture is obtained by uniformly mixing Loctite 406 and ethyl acetate at a volume ratio of 1:10; the temperature-sensitive hydrogel type body obtained in step III is the lower layer, and the magnetic responsive hydrogel type body obtained in step VI is the upper layer. The glue mixture is coated between the upper and lower layers for bonding, thereby preparing a 3D printed double-layer magnetic responsive hydrogel. The double-layer magnetic responsive hydrogel can undergo a 4D deformation process under the magnetic field generated by the current.
[0081] The double-layer magnetic responsive hydrogel sample prepared in this example can deform under the magnetic field, and the entire deformation process takes 4.9 min. The temperature-sensitive gel in the lower layer remains in a stable gel state under this condition and has no flowability.
[0082] The double-layer magnetic responsive hydrogel prepared in this example has a residual magnetization of 4.53 emu / g, a Young's modulus of 5.13 kPa, and an elongation at break of 270%.
Claims
1. A method for preparing a 3D-printed double-layer magnetically responsive hydrogel, characterized in that: The method proceeds as follows:
1. Weigh 0.1-1 parts of N,N'-methylenebisacrylamide, 0.1-1 parts of photoinitiator, 10-30 parts of water, 5-10 parts of sodium magnesium lithium silicate, 5-10 parts of recrystallized N-isopropylacrylamide and 1-5 parts of dimethylaminopropylmethylacrylamide according to the weight ratio; 2. Add N,N'-methylenebisacrylamide and photoinitiator to water in sequence, stir for 5 to 15 minutes, then add sodium magnesium lithium silicate to the aqueous solution in batches under stirring within 10 to 30 seconds, and continue stirring until the mixed solution presents a gel state; after the mixed solution presents a gel state, add recrystallized N-isopropylacrylamide and dimethylaminopropylmethylpropionamide to the mixed solution under nitrogen protection, stir for 2 to 3 hours, and then transfer to a centrifuge to remove bubbles in the gel solution to obtain a temperature-sensitive deformation gel solution; 3. Add the thermosensitive deformable gel liquid to the 3D printer and perform 3D extrusion printing. After printing, the printing liquid relies on its own self-supporting effect to maintain the printed shape to obtain a gel body. The body is then transferred to a UV curing lamp for light curing for 2 to 3 minutes to obtain a solid body. The solid body is then transferred to room temperature deionized water to fully swell and remove unreacted monomers to obtain a thermosensitive hydrogel body.
4. Weigh ferric chloride hexahydrate and ferrous chloride tetrahydrate and add them to deionized water. Stir magnetically to dissolve the solid particles completely to obtain an aqueous solution of iron salt ions. 2+ with Fe 3+ The molar ratio is 1:1; 5. Immersing the deswelled thermosensitive hydrogel body in an aqueous solution of iron salt ions for 36 to 48 hours to allow the thermosensitive hydrogel body to fully swell, thereby obtaining a swollen thermosensitive hydrogel body; 6. Transfer the swollen thermosensitive hydrogel body into a NaOH solution and keep it for 20 to 24 hours to obtain a magnetically responsive hydrogel body; 7. The thermosensitive hydrogel body obtained in step 3 is bonded to the magnetic responsive hydrogel body obtained in step 6, with the lower layer being the thermosensitive hydrogel and the upper layer being the magnetic responsive hydrogel, to prepare a 3D printed double-layer magnetic responsive hydrogel.
2. The method for preparing a 3D-printed double-layer magnetically responsive hydrogel according to claim 1, wherein: The photoinitiator described in step 1 is (2,4,6-trimethylbenzoyl)diphenylphosphine oxide.
3. The method for preparing a 3D-printed double-layer magnetically responsive hydrogel according to claim 1 or 2, characterized in that: In step 1, 0.5 to 1 part of N,N'-methylenebisacrylamide, 0.2 to 0.5 part of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 10 to 30 parts of water, 5 to 10 parts of sodium magnesium lithium silicate, 5 to 10 parts of recrystallized N-isopropylacrylamide and 1 to 5 parts of dimethylaminopropylmethylpropionamide are weighed in parts by weight.
4. The method for preparing a 3D-printed double-layer magnetically responsive hydrogel according to claim 1 or 2, wherein: The preparation method of recrystallized N-isopropylacrylamide described in step 1 is as follows: 10 g of NIPAM is weighed and dissolved in toluene, heated to 60° C. in a magnetic stirring water bath at 400 rpm until completely dissolved, 40 mL of n-hexane is added to the solution, and the solution is kept at 60° C. and stirred for 20 minutes; toluene and n-hexane are added again, and the process is repeated twice; the mixed solution is filtered to remove the undissolved polymerization inhibitor, the filtrate is allowed to stand in a -20° C. refrigerator for 12 hours, the filtrate is filtered to remove white flocculent crystals, and the NIPAM crystals are obtained by freeze-drying.
5. The method for preparing a 3D-printed double-layer magnetically responsive hydrogel according to claim 1 or 2, characterized in that: The specific steps of 3D extrusion printing described in step three are: saving the built body model as a file with the suffix -stl format, importing the model into the RepetierHost software to adjust the printing position and size, slicing the model, and then setting the printer parameters. After that, use a dual-head direct writing printer for 3D extrusion printing; the printer parameters are: the extrusion 3D printing equipment used has a printing speed of 10 to 30 mm / s, a Teflon needle with a diameter of 0.4 to 1.2 mm is used as the 3D printing needle, the printing needle height is set between 0.7 and 1.2 mm, and the printing liquid extrusion speed is 10 mm / s.
6. The method for preparing a 3D-printed double-layer magnetically responsive hydrogel according to claim 1 or 2, characterized in that: The solidified body described in step 3 is transferred to deionized water at room temperature to fully swell, which is to soak the solidified body in deionized water at room temperature for 24 hours to fully swell.
7. The method for preparing a 3D-printed double-layer magnetically responsive hydrogel according to claim 1 or 2, characterized in that: The wavelength of the ultraviolet curing lamp described in step 3 is 365nm.
8. The method for preparing a 3D-printed double-layer magnetically responsive hydrogel according to claim 1 or 2, characterized in that: The method for deswelling the thermosensitive hydrogel body in step 5 is as follows: first, the thermosensitive hydrogel body is fully soaked in deionized water at room temperature for 40 to 48 hours to remove unreacted impurities, and then transferred to 80° C. hot water for 1 to 2 hours to shrink and deswell.
9. The method for preparing a 3D-printed double-layer magnetically responsive hydrogel according to claim 1 or 2, characterized in that: The concentration of the NaOH solution in step five is 1 to 5 mol / L.
10. The method for preparing a 3D-printed double-layer magnetically responsive hydrogel according to claim 1 or 2, characterized in that: The bonding method described in step seven is: mixing Loctite 406 and ethyl acetate in a volume ratio of 1:10 to obtain a glue mixture; then bonding the thermosensitive hydrogel body and the magnetic responsive hydrogel body with the glue mixture to prepare a double-layer magnetic responsive hydrogel.