Multi-stimulus-response reprogrammable shape deformation method

Abstract

The invention relates to a multi-stimulus-response reprogrammable shape deformation method, and belongs to the field of functional materials. The shape deformation method comprises the following steps: heating the multi-stimulus response nano composite material to a glass-transition temperature, and inducing the nano composite material to deform through external constraint; heating until the temperature exceeds the topological freezing transition temperature, so that a dynamic cross-linked network in a resin matrix of the nano composite material is activated and recombined, and releasing stress to obtain a completely reshaped composite material; cooling and removing the external constraint, and raising the temperature to a glass-transition temperature to realize deformation programming of the nano composite material; the temperature is increased to the glass transition temperature after cooling, and the nanocomposite recovers to the permanent shape after reshaping; the nano composite material is a resin matrix composite material containing dynamic covalent bonds. The method is easy and convenient to operate, various in stimulation and rapid in response, the shape of the material can be reprogrammed, the shape memory function is achieved, and the shape of the formed material is changed.

Description

Technical Field

[0001] The present invention specifically relates to a multi-stimulus responsive reprogrammable shape deformation method, which is applied in the field of functional materials. Background Art

[0002] Stimuli-responsive materials can undergo physical or chemical transformations under external stimuli such as magnetism, electricity, light, heat, pH, etc. Taking traditional stimuli-responsive polymers as an example, most of them can only respond to a single stimulus, such as deformation due to thermal stimulation, while materials with multiple responses can produce corresponding changes in response to more environmental stimuli. They are in great demand in important engineering applications such as biomedicine and drive devices. It has become a top priority to develop new multi-stimulus responsive shape deformation methods.

[0003] Shape memory effect is one of the important methods to achieve shape deformation. When the material is heated to the glass transition temperature (T g When the temperature is above 400 °C, the deformation is generated by external force constraint, the temperature is lowered and the external force is removed, the temporary shape is fixed to realize programming, and the temperature is raised above the glass transition temperature again, and it will restore the original shape, that is, the shape memory function is realized. Shape memory depends on the mechanical design of temperature and deformation. Most traditional shape memory materials can only increase the temperature by convection heating and deform by contact forces such as stretching, torsion and shear. Therefore, the application of a single stimulus response mode is limited in complex working conditions. The development of multiple stimulus response modes is expected to achieve diversified controllable heating and non-contact remote deformation by using special stimulus response modes. This is an important development direction in the current field. In addition, the initial shape of traditional shape memory polymers cannot be changed again once they are cured. Taking the commonly used thermosetting resin-based composite materials as an example, they have good mechanical properties and shape deformation potential, but their permanent cured shape limits the flexible design and adjustment of shape deformation functions.

[0004] Therefore, in view of the current limitations of single stimulus responsive materials that are difficult to use for complex engineering needs and the problem that traditional thermosetting shape memory polymer materials are difficult to change the permanently cured molded shape, there is an urgent need to develop new multi-stimulus responsive shape deformation methods to cope with the increasingly complex engineering application scenarios. On the one hand, it is necessary to use multi-stimulus response to achieve deformation programming and shape memory of complex shapes. On the other hand, it is necessary to break through the limitation that traditional thermosetting shape memory polymer materials cannot be reshaped. Summary of the invention

[0005] In view of the problems that the traditional thermosetting composite material shape deformation method takes a long time, has a complicated operation process, can only respond to a single external stimulus, and cannot change the original shape of the formed material, the present invention provides a multi-stimulus response and reprogrammable shape deformation method. The advantages of this method are that the implementation method is simple, the stimulus response is fast, the shape of the material can be reprogrammed, it has a shape memory function, and the shape of the formed material can be changed.

[0006] The present invention is implemented by the following technical solutions:

[0007] The present invention provides a multi-stimulus response reprogrammable shape deformation method, comprising the following steps:

[0008] After heating the multi-stimulus responsive nanocomposite material to the glass transition temperature, inducing the multi-stimulus responsive nanocomposite material to deform by external constraints; continuing to heat the material to a temperature exceeding the topological freezing transition temperature so that the dynamic cross-linked network inside the resin matrix of the multi-stimulus responsive nanocomposite material is activated and reorganized, releasing stress, and obtaining a fully reshaped composite material; the multi-stimulus responsive nanocomposite material is a resin matrix composite material containing dynamic covalent bonds;

[0009] Cooling down and removing external constraints, and heating up to the glass transition temperature again to achieve deformation programming of the multi-stimulus responsive nanocomposite material;

[0010] After cooling down and then heating up to the glass transition temperature, the multi-stimulus responsive nanocomposite material recovers to its permanent shape after being reshaped, thereby achieving multi-stimulus responsive reprogrammable shape deformation.

[0011] As a preferred embodiment of the present invention, the heating method is convection heating, photothermal effect heating or magnetocaloric effect heating; the external constraint is a contact external force constraint or a non-contact external force constraint, the contact external force constraint is carried out by stretching, compression, bending or torsion, and the non-contact external force constraint is magnetic field guidance.

[0012] As a preferred embodiment of the present invention, the dynamic covalent bond is one or a combination of ester bond, thioester bond, amide bond, imine bond, borane bond, borate ester bond, thioether bond or disulfide bond.

[0013] As a preferred embodiment of the present invention, the multi-stimulus responsive nanocomposite material is prepared using epoxy A resin monomer as a raw material and polyacid or anhydride substances as a curing agent under the action of a catalyst.

[0014] Furthermore, the polyacid is selected from sebacic acid, benzoic acid, dimer fatty acid or trimer fatty acid, the acid anhydride substance is selected from phthalic anhydride, glutaric anhydride, methyltetrahydrophthalic anhydride or maleic anhydride, and the catalyst is selected from 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,4-diazabicyclo[2.2.2]octane, zinc acetylacetonate, zinc acetate or N,N-dimethylformamide.

[0015] Furthermore, the epoxy A resin monomer, curing agent and catalyst are mixed in a molar ratio of epoxy functional group: carboxyl functional group: catalyst of 1.0-2.0:0.5-1.5:0.05-0.15.

[0016] Furthermore, after the epoxy A resin monomer and the fixing agent are mixed, melted and evenly dispersed, a catalyst is added and cured to obtain the multi-stimulus responsive nanocomposite material.

[0017] As a preferred embodiment of the present invention, fillers are added to the multi-stimulus responsive nanocomposite material during preparation to make the multi-stimulus responsive nanocomposite material magnetic. The added fillers have magnetic properties, and the temperature of the nanocomposite material changes with the change of the applied magnetic field strength, thereby realizing programming and reshaping. It can also be attracted by a permanent magnet or an electromagnet magnetic field to change its shape after being softened by heating, thereby realizing magnetic field attraction deformation.

[0018] Furthermore, the filler is selected from nano-ferroferric oxide particles, cobalt ferrite or nickel-zinc ferrite.

[0019] Furthermore, based on the total mass of the mixed system consisting of the epoxy A resin monomer, the curing agent, the catalyst and the filler, the added amount of the filler is 5wt% to 30wt%. After the concentration of the filler in the resin matrix is ​​further increased, the glass transition temperature of the nanocomposite material is significantly reduced, which is more conducive to achieving complex shape deformation, and its magnetic response performance is also more superior.

[0020] As a preferred embodiment of the present invention, the multi-stimulus responsive nanocomposite material is placed on a heating table of a magnetic field heating instrument during heating, the power of the instrument is set to 820-2000W, and the current is set to 200-480A, in order to ensure that the sample can achieve deformation, shape memory and reshaping in different temperature ranges.

[0021] As a preferred embodiment of the present invention, the topological freezing transition temperature T of the multi-stimulus responsive nanocomposite material is vThe temperature is 140-250°C, at which point the multi-stimulus responsive nanocomposite material will slowly change shape under the constraint of external force and continue to be heated at the current temperature for 15-90 minutes, in order to maintain a smaller deformation rate and achieve a reshaping effect without destroying the structure of the multi-stimulus responsive nanocomposite material itself, thereby completely changing the shape of the multi-stimulus responsive nanocomposite material.

[0022] As a preferred embodiment of the present invention, the glass transition temperature T g It is 70~120℃.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The method provided by the present invention introduces dynamic covalent bonds into the resin matrix of the multi-stimulus responsive nanocomposite material. The rearrangement of the network topology caused by the dynamic covalent bonds is the key to the multi-stimulus responsive nanocomposite material being able to be reprogrammed to change the structure or even completely reshaped. This method only requires the presence of dynamic covalent bonds in the resin matrix, such as ester bonds, thioester bonds, amide bonds, imine bonds, boron oxygen bonds, borate bonds, thioether bonds or disulfide bonds, and the composite material can achieve arbitrary shape changes and reprogramming. The deformation principle is that the dynamic network inside the resin matrix moves under external stimulation, and the material is deformed accordingly; when the material temperature is lower than the glass transition temperature T g When the internal dynamic network is frozen, the new shape formed is preserved. For permanent reshaping of the original shape, when the material temperature rises to the topological freezing transition temperature, T v At the above times, the internal dynamic bond exchange reaction intensifies and the dynamic network topological structure is reorganized, so that the internal network structure after deformation under the action of external force is transformed into a stress-free state, realizing permanent shaping of the material; when the temperature is lowered, since the internal topological network structure has been completely reorganized, the reorganized shape will be completely retained instead of the original shape, completing a thorough deformation and reshaping.

[0025] The method provided by the present invention can use multiple stimulation methods to heat the material and is not limited to a single external stimulation, such as magnetocaloric effect heating, photothermal effect heating or convection heating.

[0026] The method provided by the present invention can not only change the shape of the material through traditional contact external force constraint deformation methods such as stretching, compression, bending or twisting, but also adopt non-contact deformation methods such as using the magnetic field of a permanent magnet or an electromagnet to achieve material deformation through magnetic field attraction.

[0027] The method provided by the present invention can be widely used in the reshaping of multi-stimulus responsive nanocomposite materials. The multi-stimulus responsive reprogrammable shape deformation method proposed by the present invention is easy to operate, has diverse stimuli, and responds quickly. It can realize deformation of various complex shapes and has shape memory function. It can permanently change the structure of the formed material. For example, with the help of a magnetic field, it can achieve a rapid temperature rise of 140°C / min, and then only needs to be kept at 200°C for 30 minutes to achieve complete reshaping of various complex configurations, and the reshaped material still has excellent mechanical properties and load-bearing capacity. It breaks through the limitations of traditional shape deformation methods, such as complex operation procedures, slow stimulus response, and inability to change the shape of the original material.

[0028] The stimulus responses in the present invention can be used in combination with each other to achieve deformation of complex shapes and even permanent reshaping, such as applying an external magnetic field to guide and assist deformation of materials deformed by laser heating.

[0029] The present invention selects epoxy A resin monomer, polyacid or acid anhydride, and catalyst as the preparation system for preparing multi-stimulus corresponding nanocomposite materials. Among them, the polyacid can be sebacic acid, benzoic acid, dimer fatty acid or trimer fatty acid, and the acid anhydride material is selected from phthalic anhydride, glutaric anhydride, methyltetrahydrophthalic anhydride or maleic anhydride; the catalyst can be 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,4-diazabicyclo[2.2.2]octane, zinc acetylacetonate, zinc acetate or N,N-dimethylformamide. At the same time, magnetic fillers are doped in the preparation process of the nanocomposite material, so that the nanocomposite material has the characteristic that the temperature changes with the change of the applied magnetic field strength, and then complex programming and reshaping can be realized. It can also be attracted by the permanent magnet or electromagnet magnetic field to change the shape after heating and softening, so as to realize magnetic field attraction deformation. Due to the selection of the nanocomposite material preparation system and magnetic materials, the nanocomposite material in the present invention has the function of multiple stimulus responses, and can realize rapid response of multiple stimuli of heat, light or magnetism. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of the multi-stimulus responsive reprogrammable shape deformation method of the present invention.

[0031] Figure 2 It is a schematic diagram of three heating methods in the present invention.

[0032] Figure 3 It is a schematic diagram of utilizing magnetic field to assist material deformation in the present invention.

[0033] Figure 4 Schematic diagram of the mechanism of reprogrammable shape deformation in the present invention.

[0034] Figure 5It is a schematic diagram of a specific implementation of the reprogrammable shape deformation method of the present invention.

[0035] Figure 6 It is a schematic diagram of the shape deformation of the magnetic field guiding material in the present invention. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0037] Stimulus-responsive materials can undergo reversible physical or chemical transformations under external stimuli such as magnetism, electricity, light, heat, and pH, while materials with multiple responses can produce corresponding changes in response to more environmental stimuli. They are in great demand in important engineering applications such as biomedicine and sensing technology. For example, nanoparticles in photothermal therapy have both light and heat responses, achieving better results.

[0038] However, the current means of stimulating the temperature change and deformation of materials all have certain limitations. In addition, for traditional shape memory polymers, once the initial shape is determined, it cannot be changed at all. Taking the commonly used thermosetting composite materials as an example, they have good mechanical properties, but it is extremely difficult to change the shape of the cured material, which limits the flexible design and adjustment of the shape deformation function. Unlike traditional stimulus response, multi-stimulus response means more stimulation methods to cause the material to change its temperature, and special stimulation such as magnetic field attraction can be used to achieve the shape change of the material, thereby realizing the reshaping and reprogramming of the material. Therefore, using multi-stimulus response to achieve multiple heating methods and non-contact remote deformation methods not only meets the increasingly diverse production practices and engineering application needs, but is also the key to achieving the permanent shape reshaping of shape memory materials and thus achieving complex shape reprogramming.

[0039] The present invention provides a multi-stimulus responsive reprogrammable shape deformation method, which can be applied to the reshaping of complex structures, comprising the following steps:

[0040] After heating the multi-stimulus responsive nanocomposite material to the glass transition temperature, inducing the multi-stimulus responsive nanocomposite material to deform by external constraints; continuing to heat the material to a temperature exceeding the topological freezing transition temperature so that the dynamic cross-linked network inside the resin matrix of the multi-stimulus responsive nanocomposite material is activated and reorganized, releasing stress, and obtaining a fully reshaped composite material; the multi-stimulus responsive nanocomposite material is a resin matrix composite material containing dynamic covalent bonds;

[0041] Cooling down and removing external constraints, and heating up to the glass transition temperature again to achieve deformation programming of the multi-stimulus responsive nanocomposite material;

[0042] After cooling down and then heating up to the glass transition temperature, the multi-stimulus responsive nanocomposite material recovers to the permanent shape after being reshaped.

[0043] Figure 1 That is a flow chart of the multi-stimulus responsive reprogrammable shape deformation method provided by the present invention, for preparing a multi-stimulus responsive nanocomposite material.

[0044] Figure 2 Temperature changes can be achieved by using stimulation methods such as light, magnetic field, and convection heating. Magnetic fields can also be used. Figure 3 Realize non-contact material shape control.

[0045] Figure 4 The diagram is a mechanism diagram of the reprogrammable shape deformation in the present invention. Above the glass transition temperature, as the temperature increases, the internal bond exchange reaction of the resin matrix of the multi-stimulus responsive nanocomposite material gradually accelerates, the dynamic network structure is reorganized, and under external stimulation and induction, the original shape of the material is gradually changed. When the temperature enters a higher topological freezing transition temperature, the internal bond exchange reaction is intense, and the rate at which the molecular chain network transforms to a stress-free state is faster. If certain constraints are applied, the shape can be completely reshaped after a period of time. It should be noted that the shape memory function does not change the structure of the molecular chain network, and the reshaping process completely changes the topological structure of the internal network.

[0046] In addition, in the present invention, as long as there are dynamic covalent bonds in the resin matrix, dynamic bond exchange reactions can occur, and reprogrammable arbitrary shape deformation can be achieved. The dynamic covalent bonds include ester bonds, thioester bonds, amide bonds, imine bonds, boron oxygen bonds, borate ester bonds, thioether bonds or disulfide bonds.

[0047] The stimulation means in the present invention is not limited to a single stimulation, and multiple stimulation means may be used to heat the material, such as convection heating, photothermal heating or magnetocaloric heating.

[0048] The deformation method in the present invention is not limited to traditional shape deformation means such as stretching and twisting, and magnetic field-assisted attraction can be used to achieve material reshaping and complex shape programming.

[0049] The reprogrammable shape deformation method of the present invention, such as Figure 5 As shown, the principle is to use the resin matrix in two characteristic temperature ranges, namely the glass transition temperature T g and topological freezing transition temperature T vWhen the material is heated to a temperature lower than the glass transition temperature, the dynamic bond exchange reaction inside the resin matrix causes the dynamic network structure to be reorganized, thereby achieving reshaping. In the glass transition temperature range, the material is softened by increasing the temperature, so that the material can be reprogrammed into any shape under the action of external force. When the temperature is lowered to below the glass transition temperature, the internal dynamic network is frozen, so that the new shape formed is retained. After reheating, the material returns to its original shape, achieving shape memory. For permanent reshaping of the original shape, when the material temperature rises to the topological freezing transition temperature, i.e., T v When the temperature is lowered, the internal topological network structure has been completely reorganized, so the reorganized shape will be completely retained instead of the original shape, completing the complete deformation and reshaping. For various types of complex components, it only takes 30 minutes to achieve complete reshaping, and the shaping time can be shortened by changing different material preparation ratios and experimental conditions.

[0050] The multi-stimulus responsive reprogrammable shape deformation method provided by the present invention has the advantages of low cost, simple operation process, excellent reliability, the ability to respond to multiple stimuli, and the ability to achieve permanent reshaping and reprogramming of the structural shape of the material.

[0051] The present invention selects epoxy A resin monomer, polyacid or acid anhydride, and catalyst as the preparation system for preparing multi-stimulus corresponding nanocomposite materials. Among them, the polyacid can be sebacic acid, benzoic acid, dimer fatty acid or trimer fatty acid, and the acid anhydride material is selected from phthalic anhydride, glutaric anhydride, methyltetrahydrophthalic anhydride or maleic anhydride; the catalyst can be 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,4-diazabicyclo[2.2.2]octane, zinc acetylacetonate, zinc acetate or N,N-dimethylformamide. At the same time, magnetic fillers are doped in the preparation process of the nanocomposite material, so that the material has the characteristic that the temperature changes with the change of the applied magnetic field strength, and then complex programming and reshaping can be realized. It can also be attracted by a permanent magnet or an electromagnet magnetic field to change its shape after heating and softening, thereby realizing magnetic field attraction deformation. Due to the specific selection of the nanocomposite material preparation system and the magnetic filler, the nanocomposite material in the present invention has the function of multiple stimulus responses, and can achieve rapid response to multiple stimuli of heat, light or magnetism.

[0052] Preferably, the polyacid is sebacic acid, the catalyst is 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and the reaction speed of the system is faster when sebacic acid is used as a curing agent than when anhydride substances are used as curing agents. At the same time, 1,5,7-triazabicyclo[4.4.0]dec-5-ene can further increase the reaction rate of the system.

[0053] In summary, the multi-stimulus responsive reprogrammable shape deformation method provided by the present invention is easy to operate, has diverse stimuli, and responds quickly. It can reprogram existing shapes to achieve shape memory and can achieve permanent shaping of the initial structure.

[0054] Example 1

[0055] Preparation of multi-stimulus responsive nanocomposites

[0056] In this embodiment, the uniformity of nanoparticles in the polymer solution is first achieved. Currently, the nanoparticle dispersion methods include physical means such as grinding, ultrasonic dispersion, mechanical stirring, etc. and chemical means such as acid and alkali washing, sol adsorption, etc. In this embodiment, mechanical stirring is used to disperse the nanoparticles; the added nanomaterial is nano-iron oxide particles, the particle size is 20 nanometers, and the purity is 99.5%;

[0057] The main reactant components of the resin matrix of the nanocomposite material are bisphenol A diglycidyl ether monomer, sebacic acid and catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene;

[0058] The bisphenol A diglycidyl ether monomer and sebacic acid were preheated and melted at 150°C, stirred at 150°C with a magnetic stirrer for 40 minutes until uniform, and 5wt% of the total mass of the mixed system consisting of epoxy A resin monomer, curing agent, catalyst and nano-iron tetroxide particles was added, and then mechanical stirring was used for 60 minutes to ensure that the nanoparticles in the solution were evenly dispersed. After stirring, the solution was cooled to 130°C and the catalyst was added, and the catalyst was quickly stirred for 3 minutes until the catalyst was completely dissolved. Bisphenol A diglycidyl ether monomer, curing agent sebacic acid, and catalyst were added according to the molar ratio of epoxy functional group: carboxyl functional group: catalyst of 1.5:1:0.1. Finally, the solution was vacuumed for 6 minutes at a temperature of 130°C to eliminate bubbles in the solution, and the vacuuming time should not be too long to prevent the material from curing prematurely. Finally, the polymer solution was poured into the treated mold and cured in an oven at 160°C for 12 hours to finally obtain a multi-stimulus responsive nanocomposite material.

[0059] Example 2

[0060] Deforming and reshaping materials with convection heating

[0061] The nanocomposite material prepared in Example 1 was selected and convection heated in a high temperature oven ( Figure 2 ). Set the oven temperature to 180°C, the material softens due to heat, and then changes shape under contact external forces such as bending or molds of different shapes. At the same time, high temperature activates the bond exchange reaction inside the resin matrix, so that the dynamic network topology is reorganized, and the network configuration is transformed to a stress-free state, and finally a complete reshaping is achieved. After complete reshaping, cool down, remove the external force after the sample is completely cooled, and heat up to 100°C again with the help of the oven. After the material softens due to heat, the material is deformed under contact external forces such as bending or molds of different shapes, and then multiple shape reprogramming is completed. After the sample is completely cooled after cooling down, it will retain the temporary shape after programming. At this time, the temperature is raised to 100°C again, and the sample slowly returns to the shape of the sample after reshaping.

[0062] Example 3

[0063] The nanocomposite material prepared in Example 1 was selected and convection heated in a high temperature oven ( Figure 2 ). Set the oven temperature to 180°C, the material softens due to heat, and then deforms under the guidance of a non-contact magnetic field. At the same time, high temperature activates the bond exchange reaction inside the resin matrix, so that the dynamic network topology is reorganized, and the network configuration is transformed into a stress-free state, and finally a complete reshaping is achieved. After complete reshaping, cool down, remove the external force after the sample is completely cooled, and heat up to 100°C again with the help of an oven. After the material softens due to heat, it deforms under the guidance of a non-contact magnetic field, and then completes the reprogramming of various shapes. After the sample is completely cooled after cooling down, it will retain the temporary shape after programming. At this time, the temperature is raised to 100°C again, and the sample slowly returns to the shape of the sample after reshaping.

[0064] Example 4

[0065] Deforming and reshaping materials using photothermal effects

[0066] The nanocomposite material prepared in Example 1 was selected and irradiated with an 808 nm infrared laser. The current was set to 1.35 A and the laser power was set to 2.75 W / cm 2 , realize photothermal heating ( Figure 2 ).

[0067] The material temperature is maintained at 250°C by laser irradiation, and the sample is reshaped under contact external forces such as bending or molds of different shapes. The sample is cooled after it is completely reshaped. After cooling, the sample is completely reshaped into a new permanent shape, that is, light stimulus response reshaping is achieved. After complete cooling, the laser is used to heat it again to 120°C. After the material is softened by heat, various complex shapes are programmed under contact external forces such as bending or molds of different shapes. After the sample is completely cooled after cooling, it will retain the temporary shape after programming. At this time, it is heated to 120°C again, and the sample slowly returns to the shape of the sample after reshaping, that is, shape memory under light stimulus response is achieved. In the experiment, the heating rate of the sample can reach 22°C / min, and the highest temperature is 308°C, which shows that laser heating only requires a small power to greatly increase the heating rate of the material, and no additional equipment such as wires is required to connect the materials. This feature can be used to achieve more complex structural deformation and reshaping.

[0068] Example 5

[0069] The nanocomposite material prepared in Example 1 was selected and irradiated with an 808 nm infrared laser. The current was set to 1.35 A and the laser power was set to 2.75 W / cm 2 , realize photothermal heating ( Figure 2 ).

[0070] The material temperature is maintained at 250°C by laser irradiation, and a non-contact magnetic field is applied to guide the deformation. The sample is reshaped under the combined action of the two. After the sample is completely reshaped, the temperature is lowered. After cooling, the sample is completely reshaped into a new permanent shape, that is, light stimulus response reshaping is achieved. After complete cooling, the laser is used to heat it again to 120°C. After the material is softened by heat, a non-contact magnetic field is applied to guide the material to deform, and the programming of various complex shapes is achieved. After the sample is completely cooled after cooling, it will retain the temporary shape after programming. At this time, the temperature is raised to 120°C again, and the sample slowly returns to the shape of the sample after reshaping, that is, shape memory under light stimulus response is achieved.

[0071] Example 6

[0072] Using magnetocaloric effect to deform and shape materials

[0073] The nanocomposite material in Example 1 was selected and the material in the coil was heated by an alternating magnetic field generated by an Easy Heat 224 instrument ( Figure 2 ), the operating power is set to 2000W, the current is set to 480A, and the operating frequency is 215kHz.

[0074] The material is heated to 210°C with the help of a magnetic field. The material softens due to heat, and then the material is guided to deform under contact external forces such as bending or molds of different shapes. The material is kept warm for 30 minutes to achieve complete reshaping of the sample. After cooling, the sample obtains a new permanent shape, that is, reshaping in response to magnetic field stimulation is achieved. Subsequently, the instrument power is adjusted to 820W, the current is set to 200A, and the sample is reheated to 90°C. After softening due to heat, shape programming can be achieved under contact external forces such as bending or molds of different shapes. After the sample is completely cooled after cooling, it will retain the temporary shape after programming. At this time, it is heated to 90°C again, and the sample slowly returns to the shape of the sample after reshaping, that is, shape memory in response to magnetic field stimulation is achieved. If you want to shorten the time required for reshaping, you can increase the power, current, frequency and other parameters of the instrument.

[0075] Example 7

[0076] The nanocomposite material in Example 1 was selected and the material in the coil was heated by an alternating magnetic field generated by an Easy Heat 224 instrument ( Figure 2 ), the operating power is set to 2000W, the current is set to 480A, and the operating frequency is 215kHz.

[0077] With the help of a magnetic field, the material is heated to 210°C, the material softens due to heat, and then a non-contact magnetic field is used to guide the material to deform, and the temperature is kept for 30 minutes to achieve complete reshaping of the sample. After cooling, the sample obtains a new permanent shape, that is, the reshaping in response to magnetic field stimulation is achieved. Subsequently, the instrument power is adjusted to 820W, the current is set to 200A, the sample is reheated to 90°C, and a non-contact magnetic field is applied to guide the material to deform after heat softening, so that complex shape programming can be completed. After the sample is completely cooled after cooling, it will retain the temporary shape after programming. At this time, the temperature is raised to 90°C again, and the sample slowly returns to the shape of the sample after reshaping, that is, shape memory in response to magnetic field stimulation is achieved. If you want to shorten the time required for reshaping, you can increase the power, current, frequency and other parameters of the instrument.

[0078] Example 8

[0079] Realize complex deformation, shape memory and permanent reshaping of materials

[0080] The nanocomposite material in Example 1 was selected and deformed at a temperature of 200°C using external forces and molds of different shapes. The experimental process is as follows: Figure 5As shown. At high temperatures, the material softens due to heat, and the dynamic network inside the resin matrix is ​​reorganized, making it easier for the material to deform rapidly under the action of external loads and constraints, and finally completely reshaped into a permanent shape with a completely changed internal network topology, that is, stimulus-responsive reshaping and deformation. When the sample is completely cooled, all constraints are removed, and the sample is heated up to 120°C again. After being softened by heat, the sample is deformed under the action of external force to complete the reprogramming of different shapes. After the sample is completely cooled after cooling, it will retain the temporary shape after programming. At this time, it is heated up to 120°C again, and the sample slowly returns to the shape of the sample after reshaping, successfully realizing shape memory under multi-stimulus response.

[0081] Example 9

[0082] Using magnetic fields to guide material deformation and reshaping

[0083] The nanocomposite material in Example 1 was selected, one end of which was fixed on a fixture, and a permanent magnet was used to attract the nanocomposite material according to a specified shape deformation path at a temperature of 200°C to induce deformation of the material. The experimental process is as follows: Figure 6 As shown. After being softened by heat at high temperature, the dynamic network inside the composite resin matrix is ​​reorganized, and the filled metal nanoparticles are attracted by the magnetic field due to their own magnetism, causing the material to deform, achieving shape change under the guidance of the magnetic field, and finally completing the reshaping of the material, that is, realizing the magnetic field-guided material reshaping. After the sample is completely cooled, the sample is heated up to 120°C again. After being softened by heat, a magnetic field is applied to the sample to guide it to deform, and complex shape programming can be completed. After the sample is completely cooled after cooling, it will retain the temporary shape after programming. At this time, it is heated up to 120°C again, and the sample slowly returns to the reshaped shape, that is, the shape memory of the material is realized.

[0084] Example 10

[0085] The difference from Example 2 is that the preparation method of the multi-stimulus responsive nanocomposite material is different, specifically:

[0086] The bisphenol A diglycidyl ether monomer and glutaric anhydride were preheated and melted at 100°C, stirred at 100°C with a magnetic stirrer for 20 minutes until uniform, and 5wt% of the total mass of the mixed system consisting of epoxy A resin monomer, curing agent, catalyst and nano-iron tetroxide particles was added, and then mechanical stirring was used for 30 minutes to ensure that the nanoparticles in the solution were evenly dispersed. After the stirring was completed, the catalyst zinc acetylacetonate was added and stirred for 15 minutes until the catalyst was completely dissolved. Bisphenol A diglycidyl ether monomer, curing agent glutaric anhydride, and catalyst were added according to the molar ratio of epoxy functional group: carboxyl functional group: catalyst of 1.0:0.5:0.05. Finally, the vacuum drying oven was vacuumed for 10 minutes at a temperature of 90°C to eliminate bubbles in the solution, and the vacuuming time should not be too long to prevent the material from curing prematurely. Finally, the polymer solution was poured into the treated mold and cured in an oven. The curing conditions were 2 hours at 130°C and 5 hours at 160°C to finally obtain a multi-stimulus responsive nanocomposite material.

[0087] Embodiment 11

[0088] The difference from Example 2 is that the preparation method of the multi-stimulus responsive nanocomposite material is different, specifically:

[0089] Methyltetrahydrophthalic anhydride is poured into the preheated molten bisphenol A diglycidyl ether monomer at 80°C, stirred at 80°C with a magnetic stirrer for 15 minutes until uniform, and 5wt% of the total mass of the mixed system consisting of epoxy A resin monomer, curing agent methyltetrahydrophthalic anhydride, catalyst and nano-iron tetroxide particles is added, and then mechanical stirring is used for 15 minutes. After stirring, the catalyst zinc acetylacetonate is added to the solution and stirred for 15 minutes until the catalyst is completely dissolved. Bisphenol A diglycidyl ether monomer, curing agent methyltetrahydrophthalic anhydride, and catalyst are added according to the molar ratio of epoxy functional group: curing agent functional group: catalyst of 2.0:1.5:0.15. Finally, vacuum the solution in a vacuum drying oven at a temperature of 80°C for 10 minutes to eliminate bubbles in the solution, and the vacuuming time should not be too long to prevent the material from curing prematurely. Finally, the polymer solution is poured into the treated mold and cured in an oven at 140°C for 10 hours to finally obtain a multi-stimulus responsive nanocomposite material.

[0090] Example 12

[0091] The difference from Example 2 is that the preparation method of the multi-stimulus responsive nanocomposite material is different, specifically:

[0092] Bisphenol A diglycidyl ether monomer and sebacic acid were preheated and melted at 150°C, stirred at 150°C with a magnetic stirrer for 40 minutes until uniform, and nano-iron tetroxide particles were added, which was equivalent to 30wt% of the total mass of the mixed system consisting of epoxy A resin monomer, curing agent, catalyst and nano-iron tetroxide particles, and then mechanically stirred for 60 minutes to ensure that the nanoparticles in the solution were evenly dispersed. After stirring, the solution was cooled to 130°C and the catalyst zinc acetylacetonate was added, and the catalyst was quickly stirred for 3 minutes until the catalyst was completely dissolved. Bisphenol A diglycidyl ether monomer, curing agent, and catalyst were added according to the molar ratio of epoxy functional group: carboxyl functional group: catalyst of 1.5:1:0.1. Finally, the solution was vacuumed for 6 minutes at a temperature of 130°C to eliminate bubbles in the solution, and the vacuuming time should not be too long to prevent the material from curing prematurely. Finally, the polymer solution was poured into the treated mold and cured in an oven at 160°C for 12 hours to finally obtain a multi-stimulus responsive nanocomposite material.

[0093] Example 13

[0094] The difference from Example 2 is that the preparation method of the multi-stimulus responsive nanocomposite material is different, specifically:

[0095] Preheat the bisphenol A diglycidyl ether monomer and sebacic acid at 150°C and stir them for 40 minutes at 150°C until they are uniform. Add 20wt% of the total mass of the mixed system consisting of epoxy A resin monomer, curing agent, catalyst and nano-iron tetroxide particles, and then use mechanical stirring for 60 minutes to ensure that the nanoparticles in the solution are evenly dispersed. After stirring, cool the solution to 130°C and add the catalyst N,N-dimethylformamide, and stir quickly for 3 minutes until the catalyst is completely dissolved. Bisphenol A diglycidyl ether monomer, curing agent, and catalyst are added according to the molar ratio of epoxy functional group: carboxyl functional group: catalyst of 1.5:1:0.1. Finally, vacuum the solution for 6 minutes at a temperature of 130°C to eliminate bubbles in the solution, and the vacuuming time should not be too long to prevent the material from solidifying prematurely. Finally, the polymer solution was poured into the treated mold and cured in an oven at 160°C for 12 hours to finally obtain a multi-stimulus responsive nanocomposite material.

[0096] Embodiment 14

[0097] The difference from Example 2 is that the preparation method of the multi-stimulus responsive nanocomposite material is different, specifically:

[0098] The bisphenol A diglycidyl ether monomer and sebacic acid were preheated and melted at 150°C, stirred at 150°C with a magnetic stirrer for 40 minutes until uniform, and 5wt% of the total mass of the mixed system consisting of epoxy A resin monomer, curing agent, catalyst and cobalt ferrite was added, and then mechanical stirring was used for 60 minutes to ensure that the nanoparticles in the solution were evenly dispersed. After stirring, the solution was cooled to 130°C and the catalyst was added, and the catalyst was quickly stirred for 3 minutes until the catalyst was completely dissolved. Bisphenol A diglycidyl ether monomer, curing agent, and catalyst were added according to the molar ratio of epoxy functional group: carboxyl functional group: catalyst of 1.5:1:0.1. Finally, the solution was vacuumed for 6 minutes at a temperature of 130°C to eliminate bubbles in the solution, and the vacuuming time should not be too long to prevent the material from curing prematurely. Finally, the polymer solution was poured into the treated mold and cured in an oven at 160°C for 12 hours to finally obtain a multi-stimulus responsive nanocomposite material.

[0099] Embodiment 15

[0100] The difference from Example 2 is that the preparation method of the multi-stimulus responsive nanocomposite material is different, specifically:

[0101] Bisphenol A diglycidyl ether monomer and sebacic acid were preheated and melted at 150°C, stirred at 150°C with a magnetic stirrer for 40 minutes until uniform, and nickel-zinc ferrite equivalent to 5wt% of the total mass of the mixed system consisting of epoxy A resin monomer, curing agent, catalyst and nickel-zinc ferrite was added, and then mechanical stirring was used for 60 minutes to ensure that the nanoparticles in the solution were evenly dispersed. After stirring, the solution was cooled to 130°C and the catalyst was added, and the catalyst was quickly stirred for 3 minutes until the catalyst was completely dissolved. Bisphenol A diglycidyl ether monomer, curing agent, and catalyst were added according to the molar ratio of epoxy functional group: carboxyl functional group: catalyst of 1.5:1:0.1. Finally, the solution was vacuumed for 6 minutes at a temperature of 130°C to eliminate bubbles in the solution, and the vacuuming time should not be too long to prevent the material from curing prematurely. Finally, the polymer solution was poured into the treated mold and cured in an oven at 160°C for 12 hours to finally obtain a multi-stimulus responsive nanocomposite material.

[0102] The test results of Examples 1 to 15 show that the material undergoes significant shape changes at high temperatures and is reshaped into a new permanent shape structure. External force constraints can achieve permanent reshaping of the material itself, and can also achieve complex deformation programming, while achieving stimulus response deformation through shape memory function. And because magnetic field attraction does not require contact with the sample and is flexible to use, it can also be combined with other stimulus responses to achieve more complex shape deformation programming.

[0103] The above implementation cases are only preferred embodiments of the present invention and are not intended to limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, they are not intended to limit the present invention. Therefore, any simple modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A multi-stimulus responsive reprogrammable shape deformation method, characterized in that: The following steps are involved: After heating the multi-stimulus responsive nanocomposite material to the glass transition temperature, inducing the multi-stimulus responsive nanocomposite material to deform by external constraints; continuing to heat the material to a temperature exceeding the topological freezing transition temperature so that the dynamic cross-linked network inside the resin matrix of the multi-stimulus responsive nanocomposite material is activated and reorganized, releasing stress, and obtaining a fully reshaped composite material; the multi-stimulus responsive nanocomposite material is a resin matrix composite material containing dynamic covalent bonds; Cooling down and removing external constraints, and heating up to the glass transition temperature again to achieve deformation programming of the multi-stimulus responsive nanocomposite material; After cooling down and then heating up to the glass transition temperature, the multi-stimulus responsive nanocomposite material recovers to its permanent shape after being reshaped, thereby achieving multi-stimulus responsive reprogrammable shape deformation.

2. The multi-stimulus responsive reprogrammable shape deformation method according to claim 1, characterized in that: The heating method is convection heating, photothermal effect heating or magnetocaloric effect heating; The external constraint is a contact type external force constraint or a non-contact type external force constraint. The contact type external force constraint is performed by stretching, compression, bending or twisting, and the non-contact type external force constraint is guided by a magnetic field.

3. The multi-stimulus responsive reprogrammable shape deformation method according to claim 1, characterized in that: The dynamic covalent bond is one or a combination of ester bonds, thioester bonds, amide bonds, imine bonds, boron oxygen bonds, borate ester bonds, thioether bonds or disulfide bonds.

4. The multi-stimulus responsive reprogrammable shape deformation method according to claim 3, characterized in that: The multi-stimulus responsive nanocomposite material is prepared by using epoxy A resin monomer as a raw material and polyacid or anhydride substances as a curing agent under the action of a catalyst.

5. The multi-stimulus responsive reprogrammable shape deformation method according to claim 4, characterized in that: The epoxy A resin monomer, curing agent and catalyst are mixed according to the molar ratio of epoxy functional group: carboxyl functional group: catalyst of 1.0-2.0:0.5-1.5:0.05-0.

15.

6. The multi-stimulus responsive reprogrammable shape deformation method according to claim 5, characterized in that: After the epoxy A resin monomer and the curing agent are mixed, melted and evenly dispersed, a catalyst is added, and the mixture is cured and formed to obtain the multi-stimulus responsive nanocomposite material.

7. The multi-stimulus responsive reprogrammable shape deformation method according to claim 4, characterized in that: The polyacid is selected from sebacic acid, benzoic acid, dimer fatty acid or trimer fatty acid, the acid anhydride substance is selected from phthalic anhydride, glutaric anhydride, methyltetrahydrophthalic anhydride or maleic anhydride, and the catalyst is selected from 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,4-diazabicyclo[2.2.2]octane, zinc acetylacetonate, zinc acetate or N,N-dimethylformamide.

8. The multi-stimulus responsive reprogrammable shape deformation method according to claim 4, characterized in that: Fillers are added to the multi-stimulus responsive nanocomposite material during preparation so that the multi-stimulus responsive nanocomposite material can acquire magnetic properties.

9. The multi-stimulus responsive reprogrammable shape deformation method according to claim 8, characterized in that: The filler is selected from nano-ferroferric oxide particles, cobalt ferrite or nickel-zinc ferrite.

10. The multi-stimulus responsive reprogrammable shape deformation method according to claim 8, characterized in that: Based on the total mass of the mixed system consisting of the epoxy A resin monomer, the curing agent, the catalyst and the filler, the added amount of the filler is 5wt% to 30wt%.

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