CN115141320B - 4D printable temperature-sensitive hydrogel elastomer hydrophilic and hydrophobic material and preparation method and application thereof - Google Patents

4D printable temperature-sensitive hydrogel elastomer hydrophilic and hydrophobic material and preparation method and application thereof Download PDF

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CN115141320B
CN115141320B CN202210697350.2A CN202210697350A CN115141320B CN 115141320 B CN115141320 B CN 115141320B CN 202210697350 A CN202210697350 A CN 202210697350A CN 115141320 B CN115141320 B CN 115141320B
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CN115141320A (en
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李学锋
许丹妮
张高文
舒凡
李坚
陈晗予
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Hubei University of Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
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    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
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    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F265/00—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00
    • C08F265/10—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00 on to polymers of amides or imides

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Abstract

The invention discloses a 4D printable temperature-sensitive hydrogel elastomer hydrophilic-hydrophobic material, a preparation method and application thereof, wherein hydrophilic hydrogel and a hydrophobic elastomer molecular chain are interconnected by the diffusion of an amphiphilic photoinitiator 2959 at an interface to obtain a three-dimensional product, and the product can perform spontaneous and controllable deformation movement under the water stimulation of a variable temperature. The preparation process is simple and convenient to operate, the 3D shape structure with complex structure can be constructed through 3D printing, the workpiece can be changed along with the environment, the performance is sensitive, and the method can be used as a new material of the underwater 4D soft robot.

Description

4D printable temperature-sensitive hydrogel elastomer hydrophilic and hydrophobic material and preparation method and application thereof
Technical Field
The invention relates to the field of high polymer materials, in particular to a preparation method and application of a 4D printable temperature-sensitive hydrogel-elastomer hydrophilic and hydrophobic material.
Background
4D printing refers to using 3D printing technology and plaitedMaterials of the process are used for manufacturing three-dimensional objects capable of self-changing physical properties (such as morphology, color, conductivity and the like) under the preset stimulus (such as water, temperature, electricity, light and the like). Inspired by the skin-muscle tissue of an organism, the skin serves as a first natural barrier of mammals, prevents the evaporation of skin moisture by secreting grease, and is tightly connected with the muscle tissue; muscle tissue is subjected to autonomic nerve and undergoes stress reactions such as contraction and the like under the stimulation of external environment; the mechanical properties of the skin and the muscle tissue are matched, so that the tissue is protected from being damaged easily. Among the intelligent polymer materials, hydrophilic hydrogel has a structure and performance similar to those of muscle tissues and has good biocompatibility, but is easy to dehydrate in air to cause component loss and damage; the rubber elastomer is used as a common hydrophobic polymer material, has the characteristics of high elasticity, high toughness, high stability and the like, and the combination member of the rubber elastomer and the hydrogel is similar to the functions of human skin and muscle tissue, so that on one hand, the water loss of the hydrogel and the matrix damage can be prevented; on the other hand, the soft composite material which integrates the advantages of the rubber elastomer and the hydrogel has wide application prospect in the fields of soft robots, tissue engineering and the like. However, at present, a material which has good mechanical property adaptability and can realize three-dimensional deformation along with the change of external environment is not reported by combining hydrogel and an elastomer material. In order for a 4D printed hydrogel-elastomeric hydrophilic-hydrophobic material to spontaneously deform in three dimensions under the stimulus of an external temperature change, the following conditions need to be met: 1. the precursor solution is easy to extrude and solidify under certain conditions, so that the printability of the material is realized; 2. the hydrophobic rubber elastomer has good adhesive property with hydrophilic hydrogel (the adhesive energy under water environment is more than 200J/m) 2 ) The method comprises the steps of carrying out a first treatment on the surface of the 3. Hydrogels need to have good temperature sensitivity properties; 4. the hydrogel is matched with the mechanical property of the elastomer (the tensile strength of the hydrogel is more than 10) 2 kPa, strain greater than 100%, and both bending angles exceeding 15 °).
Shao Zhufeng et al (CN 110978508 a) invented a device and method for 3D printing of silica gel, which can realize rapid printing of silica gel by providing a motion module. Li Xuefeng (CN 108276522A) and the like, and the 3D printing hydrogel bracket cured by ultraviolet light irradiation has excellent performance by soaking trivalent iron ions. The two 3D printing methods are simple and convenient to operate and are respectively applicable to various hydrogel and rubber elastomer materials; by designing parameters such as printing thickness, size and the like, the mechanical properties of the rubber elastomer and the hydrogel material can be matched. However, these two methods cannot effectively combine the hydrogel with the hydrophilic and hydrophobic silicone rubber material, so that it is difficult to achieve strong adhesion between the elastomer and the hydrogel, and it is also impossible to achieve self-transformation of physical properties under a predetermined stimulus.
Disclosure of Invention
The invention aims to solve the technical problems and provide a preparation method and application of a 4D-printable temperature-sensitive hydrogel-elastomer hydrophilic and hydrophobic material which has higher bonding strength and can spontaneously and three-dimensionally deform under temperature stimulation.
The technical scheme comprises the following specific steps:
a preparation method of a 4D printable temperature-sensitive hydrogel-elastomer hydrophilic-hydrophobic material comprises the following specific steps:
1) Adding poly (2-acrylamido-2-methylpropanesulfonate) (PNaAMPS) powder, N-isopropylacrylamide (NIPAM), acrylamide (AAm), N-Methylenebisacrylamide (MBAA) and amphiphilic photoinitiator 2-hydroxy-4- (2-hydroxyethoxy) -2-methylbenzophenone (photoinitiator 2959) into deionized water, and uniformly stirring under the shading condition to obtain poly (2-acrylamido-2-methylpropanesulfonate) (PNaAMPS)/poly (N-isopropylacrylamide-co-acrylamide) P (NIPAM-co-AAm) temperature-sensitive double-network hydrogel preprinting liquid (T-DN preprinting liquid);
2) Uniformly mixing and stirring the silicone rubber elastomer prepolymer, a photoinitiator 2959 and fumed silica powder, and stirring and defoaming by a defoaming machine to obtain uniformly mixed silicone rubber elastomer Si-E preprinting liquid;
3) Printing the Si-E pre-printing liquid obtained in the step 2) by using a 3D printer, and standing at room temperature in a dark place to perform primary solidification to obtain an Si-E printing layer;
4) And (3) printing the T-DN pre-printing liquid obtained in the step (1) on the Si-E printing layer obtained in the step (3) by using a 3D printer under the light-proof condition, and carrying out illumination cross-linking on the obtained preformed three-dimensional product to obtain the temperature sensitive T-DN/Si-E material.
Further, the PNaAMPS powder in the step 1) is obtained by drying and crushing chemically crosslinked poly (2-acrylamido-2-methylpropanesulfonate) (PNaAMPS) hydrogel, and the particle size of the PNaAMPS powder is 10-200 mu m.
Further, the molar concentration of the monomer 2-acrylamido-2-methylpropanesulfonic Acid (AMPS) in the PNaAMPS hydrogel is 1mol/L, the molar concentration of sodium hydroxide (NaOH) is 1-1.25 mol/L, the molar concentration of MBAA is 0.01-0.012 mol/L, and the molar concentration of the initiator 2-ketoglutaric acid is 0.01-0.012 mol/L.
Further, in the T-DN preprinting liquid obtained in the step 1), the mass concentration of PNaAMPS is 0.01-0.1 g/mL, the molar concentration of NIPAM is 2-3.5 mol/L, and the molar concentration of AAm is 0.5-2 mol/L.
Further, in the T-DN preprinting liquid obtained in the step 1), the molar concentration of MBAA is 0.009-0.012 mol/L, and the molar concentration of photoinitiator 2959 is 0.001-0.0013 mol/L.
Further, in the step 2), the silicone rubber elastomer component is Ecoflex00-30 silicone rubber manufactured by Smooth-On in the United states, wherein the mass ratio of the solution A to the solution B is 1:1.
further, in the Si-E preprinting liquid obtained in the step 2), the molar concentration of the photoinitiator 2959 is 0.003-0.0035 mol/L.
Further, in the Si-E preprinting liquid obtained in the step 2), the mass fraction of the fumed silica is 3-5%.
Further, in the step 3), the time of light-shielding standing and primary curing is 1 to 1.5 hours; in the step 4), the illumination conditions under the ultraviolet lamp are as follows: the illumination time is 10 hours under an ultraviolet lamp with the wavelength of 365nm and the power of 15W.
Further, the ratio of the thickness of the Si-E printing layer to the thickness of the T-DN layer after photo-crosslinking is 0.3-1.
The invention also provides a 4D printable temperature-sensitive hydrogel-elastomer hydrophilic-hydrophobic material, which is prepared by adopting the method.
The invention also provides application of the 4D printable temperature-sensitive hydrogel-elastomer hydrophilic-hydrophobic material in the field of soft robots and tissue engineering. For example, placing the 4D printed T-DN/Si-E hydrophilic-hydrophobic material product in water at 5-30 ℃, wherein the product is bent and deformed towards the hydrophobic Si-E side; and then the temperature is increased to 40-90 ℃, and the product is subjected to reverse hydrophilic T-DN side bending deformation. The product can be correspondingly bent and deformed to two sides repeatedly when the temperature is repeatedly increased and reduced.
The monomer solution before curing contains water-swellable PNaAMPS particles, the viscosity of the T-DN prepolymer solution is adjusted to be moderate by adjusting the content of PNaAMPS powder, and the 3D printing technology can be adopted to extrude lines, so that the free forming of the hydrogel is realized. Adding fumed silica into the double-component silicone rubber to obtain Si-E prepolymer, printing the T-DN prepolymer on the preliminarily cured Si-E prepolymer after preliminary curing through 3D printing, and curing under ultraviolet irradiation to obtain a T-DN/Si-E hydrophilic-hydrophobic composite structure 3D printing product with hydrophilic surfaces and hydrophobic surfaces.
Photoinitiator 2959 (2-hydroxy-4- (2-hydroxyethoxy) -2-methylpropionacetone) can be dissolved in aqueous solution or oily solution, and can be uniformly dispersed in the T-DN preprinting liquid and the Si-E preprinting liquid. In the curing process, hydroxyl and hydroxyethoxy functional groups can promote 2959 to diffuse towards the hydrophilic T-DN side at the interface, and propiophenone functional groups can also promote 2959 to diffuse towards the hydrophobic Si-E side at the interface, so that a polymer long chain in the T-DN is further covalently connected into an elastomer, the covalent connection of a hydrophilic T-DN network and a hydrophobic Si-E network at the interface is realized, and the curing of gel and the covalent interconnection of the interface are synchronously carried out, so that more covalent crosslinking points can be obtained, and further higher bonding strength is obtained.
Due to the inclusion of both hydrophilic amide groups (-CONH) in the NIPAM structure 2 ) And comprises a hydrophobic isopropyl group (-CH (CH) 3 ) 2 ) The T-DN is given temperature sensitivity, and its low critical phase transition temperature (LCST) is 35 ℃. When soaked in deionized water at 5-30 ℃, NIPAM chain segments in the T-DN network form hydrogen bonds with water inside molecules or among moleculesHydrophilic temperature-sensitive double-network hydrogel (T-DN) network can absorb water and expand, and hydrophobic Si-E is unchanged, so that the printed T-DN/Si-E is bent and deformed from the T-DN side to the Si-E side; when the temperature is raised to 40-90 ℃, namely, when the temperature is above LCST, a hydrogen bond formed by NIPAM chain segments in a T-DN network and water in molecules or among molecules is broken, water in the system is discharged rapidly, the volume is gathered and contracted, the hydrophilicity of a hydrophilic T-DN network can be obviously reduced, at the moment, the hydrogel network becomes more compact, the hydrophobicity is enhanced, so that the printed T-DN/Si-E is subjected to controllable deformation opposite to the first swelling direction, namely, bending deformation from the Si-E side to the T-DN side, and the effect that the 4D printing product can spontaneously and three-dimensionally deform under the temperature stimulation in the water environment without artificial interference is further shown.
Compared with the prior art, the invention has the following advantages and remarkable progress:
1) The invention has simple preparation process, low production cost, easily obtained raw materials, sensitive product performance, good controllability, and can realize large-scale industrial application by constructing a 3D shape structure with complex 3D printing technology.
2) According to the invention, the photoinitiator 2959 is simultaneously introduced into the hydrogel layer and the elastomer, and the amphipathy of 2959 is utilized to realize the diffusion at the interface between the T-DN and the Si-E, so that the T-DN/Si-E hydrogel-elastomer double-layer part has good adhesive property at the same time, unlike the traditional mode of chemically treating and bonding solid materials on the surface of the gel.
3) The introduction of the temperature-sensitive monomer NIPAm gives the T-DN/Si-E hydrogel-elastomer double-layer part good environmental responsiveness. The three-dimensional shape deformation can be automatically controlled under the stimulation of temperature in water environment, and the three-dimensional shape deformation device has wide application prospect in the fields of underwater intelligent soft robots and the like in the future.
Drawings
FIG. 1 is a schematic illustration of the preparation of a 4D printable T-DN/Si-E with temperature sensitivity;
FIG. 2 is a schematic diagram of a shape deformation test performed in a low and high temperature environment according to an embodiment of the present application.
Detailed Description
For a better understanding of the present invention, the following examples are further illustrative of the present invention, but the contents of the present invention are not limited to the following examples only.
The PNaAMPS adopted in the embodiment of the application is self-made, and the preparation method is as follows:
4.145g of AMPS (1 mol/L), 0.90g of NaOH (1.125 mol/L), 0.1234g of MBAA (0.01 mol/L) and 0.028g of KA (0.01 mol/L) are weighed, 20mL of deionized water is added, the mixture is stirred uniformly under the shading condition to obtain a uniform mixed solution, the uniform mixed solution is poured into a glass mold, and the uniform mixed solution is subjected to illumination polymerization under an ultraviolet lamp to obtain PNaAMPS hydrogel. Drying the PNaAMPS hydrogel to constant weight in a vacuum drying oven, ball milling and sieving to obtain PNaAMPS powder, wherein the particle size range is 10-200 mu m.
Example 1
Step 1): T-DN preprinting liquid of PNaAMPS 0.03g/mL, NIPAM 2.0mol/L, AAm 2.0.0 mol/L, photoinitiator 2959 0.001mol/L, MBAA 0.01.01 mol/L was prepared.
Step 2): and (3) placing the silicon rubber solution A, the silicon rubber solution B (Ecoflex 00-30), the photoinitiator 2959 (mass fraction 0.4%) and the gas-phase nano silicon dioxide (mass fraction 3%) in a mass ratio of 1:1 into a deaerator for high-speed stirring and deaeration to obtain the uniformly mixed Si-E preprinting liquid.
Step 3): connecting the Si-E prepolymer obtained in the step 2) on a 3D printer, wherein the 3D printer is a single-nozzle printer, adjusting the extrusion speed to ensure that the material can easily reach a nozzle, starting the printer to automatically extrude and print according to an input program, printing a layer of spline with the length of 60mm and the width of 10mm, controlling the thickness of the Si-E layer to be 0.5mm, and standing for 1 hour at room temperature in a dark place to ensure that the Si-E is primarily solidified.
Step 4): and 2) on the preliminarily solidified Si-E printing layer, automatically extruding and printing the T-DN pre-printing liquid obtained in the step 1) according to the same input program, controlling the thickness of the T-DN layer to be 1mm, and placing the printed integrated product under an ultraviolet lamp for illumination to obtain the T-DN/Si-E double-layer workpiece.
The tensile strength of T-DN/Si-E obtained in this example was 278kPa, and the elongation at break was 293%. The bond strength between hydrogel and elastomer was 657J/m 2 。
Example 2
Step 1): T-DN preprinting liquid of PNaAMPS 0.03g/mL, NIPAM 2.5mol/L, AAm 1.5.5 mol/L, photoinitiator 2959 0.001mol/L, MBAA 0.01.01 mol/L was prepared.
Step 2): and (3) placing the silicon rubber solution A, the silicon rubber solution B (Ecoflex 00-30), the photoinitiator 2959 (mass fraction 0.4%) and the gas-phase nano silicon dioxide (mass fraction 3%) in a mass ratio of 1:1 into a deaerator for high-speed stirring and deaeration to obtain the uniformly mixed Si-E preprinting liquid.
Step 3): connecting the Si-E prepolymer obtained in the step 2) on a 3D printer, wherein the 3D printer is a single-nozzle printer, adjusting the extrusion speed to ensure that the material can easily reach a nozzle, starting the printer to automatically extrude and print according to an input program, printing a layer of spline with the length of 60mm and the width of 10mm, controlling the thickness of the Si-E layer to be 0.5mm, and standing for 1 hour at room temperature in a dark place to ensure that the Si-E is primarily solidified.
Step 4): and 2) on the preliminarily solidified Si-E printing layer, automatically extruding and printing the T-DN pre-printing liquid obtained in the step 1) according to the same input program, controlling the thickness of the T-DN layer to be 1mm, and placing the printed integrated product under an ultraviolet lamp for illumination to obtain the T-DN/Si-E double-layer workpiece.
The tensile strength of the T-DN/Si-E obtained in this example was found to be 251kPa, and the elongation at break was found to be 237%.
The adhesion performance between the hydrogel and the elastomer is tested by using an electronic universal testing machine at a speed of 50mm/min through a 90 DEG peeling test, and the adhesive strength between the hydrogel and the elastomer is 589J/m 2 。
Example 3
Step 1): T-DN preprinting liquid of PNaAMPS 0.03g/mL, NIPAM 3.0mol/L, AAm 1.0.0 mol/L, photoinitiator 2959 0.001mol/L, MBAA 0.01.01 mol/L was prepared.
Step 2): and (3) placing the silicon rubber solution A, the silicon rubber solution B (Ecoflex 00-30), the photoinitiator 2959 (mass fraction 0.4%) and the gas-phase nano silicon dioxide (mass fraction 3%) in a mass ratio of 1:1 into a deaerator for high-speed stirring and deaeration to obtain the uniformly mixed Si-E preprinting liquid.
Step 3): connecting the Si-E prepolymer obtained in the step 2) on a 3D printer, wherein the 3D printer is a single-nozzle printer, adjusting the extrusion speed to ensure that the material can easily reach a nozzle, starting the printer to automatically extrude and print according to an input program, printing a layer of spline with the length of 60mm and the width of 10mm, controlling the thickness of the Si-E layer to be 0.5mm, and standing for 1 hour at room temperature in a dark place to ensure that the Si-E is primarily solidified.
Step 4): and 2) on the preliminarily solidified Si-E printing layer, automatically extruding and printing the T-DN hydrogel preprinting liquid obtained in the step 1) according to the same input program, controlling the thickness of the T-DN layer to be 1mm, and placing the printed integrated under an ultraviolet lamp for illumination to obtain the T-DN/Si-E double-layer workpiece.
The tensile strength of the T-DN/Si-E obtained in this example was found to be 230kPa and the elongation at break was found to be 161%.
The adhesion performance between the hydrogel and the elastomer is tested by using an electronic universal testing machine at a speed of 50mm/min through a 90 DEG peeling test, and the adhesion strength between the hydrogel and the elastomer is 535J/m 2 。
Example 4
Step 1): T-DN preprinting liquid of PNaAMPS 0.03g/mL, NIPAM 3.5mol/L, AAm 0.5.5 mol/L, photoinitiator 2959 0.001mol/L, MBAA 0.01.01 mol/L was prepared.
Step 2): and (3) placing the silicon rubber solution A, the silicon rubber solution B (Ecoflex 00-30), the photoinitiator 2959 (mass fraction 0.4%) and the gas-phase nano silicon dioxide (mass fraction 3%) in a mass ratio of 1:1 into a deaerator for high-speed stirring and deaeration to obtain the uniformly mixed Si-E preprinting liquid.
Step 3): connecting the Si-E elastomer prepolymer obtained in the step 2) on a 3D printer, wherein the 3D printer is a single-nozzle printer, adjusting the extrusion speed to ensure that the material can easily reach a nozzle, starting the printer to automatically extrude and print according to an input program, printing a layer of spline with the length of 60mm and the width of 10mm, controlling the thickness of the Si-E layer to be 0.5mm, and standing for 1 hour at room temperature in a dark place to ensure that the Si-E is primarily solidified.
Step 4): and 2) on the preliminarily solidified Si-E printing layer, automatically extruding and printing the T-DN pre-printing liquid obtained in the step 1) according to the same input program, controlling the thickness of the T-DN layer to be 1mm, and placing the printed integrated product under an ultraviolet lamp for illumination to obtain the T-DN/Si-E double-layer workpiece.
The tensile strength of T-DN/Si-E obtained in this example was 189kPa, and the elongation at break was 120%.
The adhesion performance between the hydrogel and the elastomer is tested by using an electronic universal testing machine at a speed of 50mm/min through a 90 DEG peeling test, and the bonding strength between the hydrogel and the elastomer is 339J/m 2 。
Comparative example 1
Step 1): a T-DN preprinting liquid of 2.5mol/L NIPAM, 0.001mol/L, MBAA and 0.01mol/L photoinitiator was prepared.
Step 2): and (3) placing the silicon rubber solution A, the silicon rubber solution B (Ecoflex 00-30), the photoinitiator 2959 (mass fraction 0.4%) and the gas-phase nano silicon dioxide (mass fraction 3%) in a mass ratio of 1:1 into a deaerator for high-speed stirring and deaeration to obtain the uniformly mixed Si-E preprinting liquid.
Step 3): connecting the Si-E prepolymer obtained in the step 2) on a 3D printer, wherein the 3D printer is a single-nozzle printer, adjusting the extrusion speed to ensure that the material can easily reach a nozzle, starting the printer to automatically extrude and print according to an input program, printing a layer of spline with the length of 60mm and the width of 10mm, controlling the thickness of the Si-E layer to be 0.5mm, and standing for 1 hour at room temperature in a dark place to ensure that the Si-E is primarily solidified.
Step 4): and 2) on the preliminarily cured Si-E printing layer in the step 2), automatically extruding and printing the hydrogel preprinting liquid obtained in the step 1) according to the same input procedure, controlling the thickness of the PNIPAM hydrogel layer to be 1mm, and placing the printed integrated product under an ultraviolet lamp for illumination to obtain the PNIPAM/Si-E double-layer workpiece.
The tensile strength of PNIPAM/Si-E obtained in this example was found to be 56kPa and the elongation at break was found to be 82%. Adhesion properties, resulting in a bond strength between hydrogel and elastomer of 109J/m 2 。
Comparative example 2
Step 1): preparing a T-DN preprinting liquid with PNaAMPS 0.03g/mL, AAm 4mol/L, photoinitiator 2959.001 mol/L, MBAA 0.01.01 mol/L.
Step 2): and (3) placing the silicon rubber solution A, the silicon rubber solution B (Ecoflex 00-30), the photoinitiator 2959 (mass fraction 0.4%) and the gas-phase nano silicon dioxide (mass fraction 3%) in a mass ratio of 1:1 into a deaerator for high-speed stirring and deaeration to obtain the uniformly mixed Si-E preprinting liquid.
Step 3): connecting the Si-E elastomer prepolymer obtained in the step 2) on a 3D printer, wherein the 3D printer is a single-nozzle printer, adjusting the extrusion speed to ensure that the material can easily reach a nozzle, starting the printer to automatically extrude and print according to an input program, printing a layer of spline with the length of 60mm and the width of 10mm, controlling the thickness of the Si-E layer to be 0.5mm, and standing for 1 hour at room temperature in a dark place to ensure that the Si-E is primarily solidified.
Step 4): and 2) on the preliminarily solidified Si-E printing layer, automatically extruding and printing the P-DN pre-printing liquid obtained in the step 1) according to the same input procedure, controlling the thickness of the P-DN hydrogel layer to be 1mm, and placing the printed integrated product under an ultraviolet lamp for illumination to obtain the P-DN/Si-E double-layer workpiece.
The tensile strength of the P-DN/Si-E obtained in this example was found to be 1500kPa and the elongation at break was found to be 1200%.
The adhesion performance between the hydrogel and the elastomer is tested by using an electronic universal testing machine at a speed of 50mm/min through a 90 DEG peeling test, and the adhesive strength between the hydrogel and the elastomer is 1050J/m 2 。
Comparative example 3
Step 1): T-DN preprinting liquid of PNaAMPS 0.03g/mL, NIPAM 3.5mol/L, AAm 0.5.5 mol/L, photoinitiator 2959 0.001mol/L, MBAA 0.01.01 mol/L was prepared.
Step 2): and (3) placing the silicon rubber A solution, the silicon rubber B solution (Ecoflex 00-30) and the gas phase nano silicon dioxide (mass fraction 3%) with the mass ratio of 1:1 into a deaerator for high-speed stirring deaeration to obtain the uniformly mixed Si-E preprinting solution.
Step 3): connecting the Si-E elastomer prepolymer obtained in the step 2) on a 3D printer, wherein the 3D printer is a single-nozzle printer, adjusting the extrusion speed to ensure that the material can easily reach a nozzle, starting the printer to automatically extrude and print according to an input program, printing a layer of spline with the length of 60mm and the width of 10mm, controlling the thickness of the Si-E layer to be 0.5mm, and standing for 1 hour at room temperature in a dark place to ensure that the Si-E is primarily solidified.
Step 4): and 2) on the preliminarily solidified Si-E printing layer, automatically extruding and printing the T-DN pre-printing liquid obtained in the step 1) according to the same input program, controlling the thickness of the T-DN layer to be 1mm, and placing the printed integrated product under an ultraviolet lamp for illumination to obtain the T-DN/Si-E double-layer workpiece.
The tensile strength of the T-DN/Si-E obtained in this example was found to be 175kPa and the elongation at break was found to be 115%.
The adhesion performance between the hydrogel and the elastomer is tested by using an electronic universal testing machine at the speed of 50mm/min through a 90 DEG peeling test, and the adhesive strength between the hydrogel and the elastomer is 48J/m 2 。
Comparative example 4
Step 1): preparing a T-DN preprinting liquid with PNaAMPS of 0.03g/mL, NIPAM of 3.5mol/L, AAm of 0.5mol/L, MBAA 0.01.01 mol/L.
Step 2): and (3) placing the silicon rubber solution A, the silicon rubber solution B (Ecoflex 00-30), the photoinitiator 2959 (mass fraction 0.4%) and the gas-phase nano silicon dioxide (mass fraction 3%) in a mass ratio of 1:1 into a deaerator for high-speed stirring and deaeration to obtain the uniformly mixed Si-E preprinting liquid.
Step 3): connecting the Si-E elastomer prepolymer obtained in the step 2) on a 3D printer, wherein the 3D printer is a single-nozzle printer, adjusting the extrusion speed to ensure that the material can easily reach a nozzle, starting the printer to automatically extrude and print according to an input program, printing a layer of spline with the length of 60mm and the width of 10mm, controlling the thickness of the Si-E layer to be 0.5mm, and standing for 1 hour at room temperature in a dark place to ensure that the Si-E is primarily solidified.
Step 4): and 2) on the preliminarily solidified Si-E printing layer, automatically extruding and printing the T-DN pre-printing liquid obtained in the step 1) according to the same input program, controlling the thickness of the T-DN layer to be 1mm, and placing the printed integrated product under an ultraviolet lamp for illumination to obtain the T-DN/Si-E double-layer workpiece.
The tensile strength of the T-DN/Si-E obtained in this example was 72kPa and the elongation at break was 53%.
Measured by 90 DEG peel test at a speed of 50mm/min by means of an electronic universal testerThe adhesion between the hydrogel and the elastomer was tested to give a bond strength of 103J/m 2 。
Comparative example 5
Step 1): preparing T-DN preprinting liquid with PNaAMPS 0.03g/mL, NIPAM 3.5mol/L, AAm 0.5mol/L and photoinitiator benzophenone 0.001mol/L, MBAA 0.01.01 mol/L.
Step 2): and (3) placing the silicon rubber solution A, the silicon rubber solution B (Ecoflex 00-30), the photoinitiator benzophenone (mass fraction 0.4%) and the gas-phase nano silicon dioxide (mass fraction 3%) in a mass ratio of 1:1 into a deaerator for high-speed stirring and deaeration to obtain the uniformly mixed Si-E preprinting liquid.
Step 3): connecting the Si-E elastomer prepolymer obtained in the step 2) on a 3D printer, wherein the 3D printer is a single-nozzle printer, adjusting the extrusion speed to ensure that the material can easily reach a nozzle, starting the printer to automatically extrude and print according to an input program, printing a layer of spline with the length of 60mm and the width of 10mm, controlling the thickness of the Si-E layer to be 0.5mm, and standing for 1 hour at room temperature in a dark place to ensure that the Si-E is primarily solidified.
Step 4): and 2) on the preliminarily solidified Si-E printing layer, automatically extruding and printing the T-DN pre-printing liquid obtained in the step 1) according to the same input program, controlling the thickness of the T-DN layer to be 1mm, and placing the printed integrated product under an ultraviolet lamp for illumination to obtain the T-DN/Si-E double-layer workpiece.
The tensile strength of T-DN/Si-E obtained in this example was found to be 159kPa and the elongation at break was found to be 100%.
The adhesion performance between the hydrogel and the elastomer is tested by using an electronic universal testing machine at a speed of 50mm/min through a 90 DEG peeling test, and the adhesive strength between the hydrogel and the elastomer is 230J/m 2 。
Temperature sensitive shape deformation test:
as shown in fig. 2, the T-DN/Si-E obtained in example 2 was measured for shape deformation in deionized water at different temperatures, and the specific steps were as follows:
1) The resulting hydrogel-elastomeric hydrophilic-hydrophobic material was cut with a knife into 20mm by 5mm by 1.5mm sized bars. Placing the sample strip into deionized water at 15 ℃, and immersing for 30 minutes to observe that the T-DN/Si-E double-layer workpiece bends from the T-DN side to the Si-E side;
2) The bending bars were again placed in 65 ℃ deionized water and after 30 minutes of soaking, a T-DN/Si-E bilayer article was observed to bend from the Si-E side to the T-DN side, the results of which are shown in table 1 below.
Table 1: temperature sensitive hydrogel-elastomer hydrophilic-hydrophobic material tensile strength, maximum tensile strain, adhesion energy between hydrogel and elastomer, and bend angle change values
Figure BDA0003702674470000091
( "+" indicates that a positive deformation occurs, i.e., a deformation in which the gel side bends toward the elastomer side; "-" means that the deformation occurs in the opposite direction, i.e. the deformation is such that the gel bends sideways to the elastomer side )
As can be seen from the data in the table:
examples 1-4 prepared temperature-sensitive T-DN/Si-E by varying the molar concentrations of NIPAm and AAm, comparative example 1 prepared PNIPAm/Si-E with temperature sensitivity, comparative example 2 prepared P-DN/Si-E without temperature sensitivity, comparative example 3 prepared temperature-sensitive T-DN/Si-E with hydrogel layer without 2959, comparative example 4 prepared temperature-sensitive T-DN/Si-E with elastomer layer without 2959, and comparative example 5 prepared temperature-sensitive T-DN/Si-E with photoinitiator benzophenone.
As can be seen from the mechanical properties of examples 1 to 4 and comparative example 1 in the tables, the tensile strength (189 to 278 kPa), the maximum tensile strain (120 to 293%) and the adhesion energy (339 to 670J/m) of T-DN/Si-E 2 ) All greater than PNIPAm/Si-E tensile strength (58 kPa), maximum tensile strain (82%) and adhesion energy (109J/m) 2 ). This is due to the design of the introduced dual network structure, the rigid PNaAMPS microgel network can act as a physical cross-linker for the polymer network, balancing the stress distribution inside the gel during deformation, further dissipating energy. Therefore, the T-DN double-network hydrogel shows more excellent mechanical property compared with PNIPAm single-network hydrogel. Meanwhile, as can be seen from the adhesion energies of comparative examples 3, 4 and 5 in the table, the T-DN/Si-E adhesion performance of the photoinitiator 2959 is better, the 2959 further covalently links the polymer long chain in the gel layer to the Si-E to realize covalent linking of the polymer long chain and the Si-E at the interface, and the adhesion energy is related to the strength of the gel per se, so that the interfacial adhesion energy between the T-DN/Si-E is stronger than that between the PNIPAm/Si-E in the 90 DEG peel test.
From the results of the temperature-sensitive shape deformation test of examples 1 to 4 and comparative example 2 in the table, it can be seen that P-DN/Si-E can only undergo forward deformation of gel-side to elastomer-side bending at both 15℃and 65℃and T-DN/Si-E can undergo deformation of gel-side to elastomer-side bending at 15℃ (forward deformation), deformation of elastomer-side to gel-side bending at 65℃ (reverse deformation), and the ability to undergo reverse deformation at 15℃gradually decreases and the ability to undergo reverse deformation at 65℃gradually increases as the molar concentration of NIPAm increases. The hydrophilic property of the hydrogel is that the hydrogel swells in water at 15 ℃, and the proportion of the hydrophobic chain segments in the copolymer gradually increases along with the increase of the molar concentration of NIPAm, so that the water absorption swelling capacity gradually weakens in a low-temperature environment (5-30 ℃), the rate of phase transition gradually increases rapidly in a high-temperature environment (40-90 ℃), the volume shrinkage is obvious, and the reverse deformation angle of the hydrogel is gradually increased in high-temperature water. Thus, the macroscopic three-dimensional product can be expressed as a 4D printed three-dimensional product which can spontaneously and three-dimensionally deform under the stimulation of temperature in water environment without human intervention.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted equally without departing from the spirit and scope of the technical solution of the present invention.

Claims (10)

1. A preparation method of a 4D printable temperature-sensitive hydrogel-elastomer hydrophilic-hydrophobic material is characterized by comprising the following steps: the method comprises the following specific steps:
1) Adding poly (2-acrylamido-2-methylpropanesulfonate) (PNaAMPS) powder, N-isopropylacrylamide (NIPAM), acrylamide (AAm), N-Methylenebisacrylamide (MBAA) and amphiphilic photoinitiator 2-hydroxy-4- (2-hydroxyethoxy) -2-methylbenzophenone (photoinitiator 2959) into deionized water, and uniformly stirring under the shading condition to obtain poly (2-acrylamido-2-methylpropanesulfonate) (PNaAMPS)/poly (N-isopropylacrylamide-co-acrylamide) P (NIPAM-co-AAm) temperature-sensitive double-network hydrogel preprinting liquid (T-DN preprinting liquid);
2) Uniformly mixing and stirring the silicone rubber elastomer prepolymer, a photoinitiator 2959 and fumed silica powder, and stirring and defoaming by a defoaming machine to obtain uniformly mixed silicone rubber elastomer Si-E preprinting liquid;
3) Printing the Si-E pre-printing liquid obtained in the step 2) by using a 3D printer, and standing at room temperature in a dark place to perform primary solidification to obtain an Si-E printing layer;
4) And (3) printing the T-DN pre-printing liquid obtained in the step (1) on the Si-E printing layer obtained in the step (3) by using a 3D printer under the light-proof condition, and carrying out illumination cross-linking on the obtained preformed three-dimensional product to obtain the temperature sensitive T-DN/Si-E material.
2. The method of manufacturing according to claim 1, wherein: the PNaAMPS powder in the step 1) is obtained by drying and crushing chemically crosslinked PNaAMPS hydrogel, and the particle size of the powder is 10-200 mu m.
3. The method of manufacturing according to claim 1, wherein: in the T-DN pre-printing liquid obtained in the step 1), the mass concentration of PNaAMPS is 0.01-0.1 g/mL, the molar concentration of NIPAM is 2-3.5 mol/L, and the molar concentration of AAm is 0.5-2 mol/L.
4. The method of manufacturing according to claim 1, wherein: in the T-DN preprinting liquid obtained in the step 1), the molar concentration of MBAA is 0.009-0.012 mol/L, and the molar concentration of photoinitiator 2959 is 0.001-0.0013 mol/L.
5. The method of manufacturing according to claim 1, wherein: in the step 2), the silicone rubber elastomer prepolymer is Ecoflex00-30 silicone rubber prepolymer A liquid and B liquid, wherein the mass ratio of the A liquid to the B liquid is 1:1.
6. the method of manufacturing according to claim 1, wherein: in the Si-E preprinting liquid obtained in the step 2), the molar concentration of the photoinitiator 2959 is 0.003-0.0035 mol/L.
7. The method of manufacturing according to claim 1, wherein: in the Si-E preprinting liquid obtained in the step 2), the mass fraction of the fumed silica is 3-5%.
8. The method of manufacturing according to claim 1, wherein: the thickness ratio of the Si-E printing layer to the T-DN layer after photo-crosslinking is 0.3-1.
9. A 4D printable temperature sensitive hydrogel-elastomeric hydrophilic-hydrophobic material prepared by the method of any one of claims 1 to 8.
10. Use of the 4D printable temperature sensitive hydrogel-elastomeric hydrophilic-hydrophobic material of claim 9 in the field of soft robotics and tissue engineering.
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