4D printing shape memory smart porthole and preparation method thereof

Abstract

This invention relates to a 4D-printed shape memory smart porthole and its fabrication method. The porthole includes at least one shielding structure placed on a glass substrate. The shielding structure consists of several parallel shielding modules, each including a support unit and a shielding unit. The central region of the shielding unit is connected to the top of the support unit. The shielding structure is integrally formed from shape memory material through 4D printing. The shielding unit has a closed state and an open state. When all shielding units in the shielding structure are in the open state, the glass substrate is shielded. The shape memory material includes the following components by mass fraction: 40%~55% shape memory polymer, 5%~10% fluorinated photocurable monomer, 10%~18% crosslinking agent, 20%~30% color-developing functional material, 1%~3% nano-functional material, 1%~2% radiation-resistant material, and 1.5%~3% photoinitiator. The 4D-printed shape memory smart porthole of this invention integrates intelligent shading, thermal regulation, and dynamic radiation resistance functions, making it suitable for complex space environments.

Description

Technical Field

[0001] This invention relates to the field of intelligent porthole system technology, particularly to the field of intelligent materials technology, and especially to a 4D printed shape memory intelligent porthole and its preparation method. Background Technology

[0002] When spacecraft windows operate in the extreme environment of space, with its intense light, strong ultraviolet radiation, and high-energy radiation coupling, they are prone to problems such as optical performance degradation, glare, increased heat load, and the initiation and propagation of microcracks, leading to deterioration of structural mechanical properties. These issues severely restrict the safety and stability of spacecraft windows during long-term on-orbit service. Traditional spacecraft windows typically rely on fixed structures or coatings for light shading and radiation protection, making it difficult to achieve adaptive adjustment under fluctuating light and space radiation intensity.

[0003] Therefore, there is an urgent need for a 4D-printed shape memory smart porthole and its fabrication method. Summary of the Invention

[0004] This invention provides a 4D-printed shape memory smart porthole and its manufacturing method. The system integrates adaptive adjustment of shading, thermal regulation and anti-radiation functions to meet the application requirements of complex space environments.

[0005] The present invention provides a 4D printed shape memory smart porthole in a first aspect, comprising at least one layer of shielding structure placed on a glass substrate; the shielding structure is composed of a plurality of parallel shielding modules, each shielding module comprising a support unit and a shielding unit; the middle region of the shielding unit is connected to the top of the support unit; The at least one layer of shielding structure is integrally formed by 4D printing using shape memory material; The shielding unit includes a closed state and an open state; when all the shielding units in the shielding plate structure are in the open state, the glass substrate is covered. The shape memory material comprises the following components by mass fraction: 40%~55% shape memory polymer, 5%~10% fluorine-containing photocurable monomer, 10%~18% crosslinking agent, 20%~30% color-developing functional material, 1%~3% nano-functional material, 1%~2% radiation-resistant material, and 1.5%~3% photoinitiator.

[0006] Preferably, when the shielding unit is in a closed state, the angle formed between the shielding unit and the supporting unit is less than 90°; When the shielding unit is in the open state, the angle between the shielding unit and the supporting unit is 90°.

[0007] Preferably, when all the blocking units are in the open state, at least one side of the blocking unit extends outward in the horizontal direction to form an extended blocking area.

[0008] More preferably, when all the shielding units in the shielding structure are in the open state, the adjacent extended shielding areas are connected in sequence.

[0009] Preferably, the blocking unit heats up to the glass transition temperature of the shape memory material and deforms after being stimulated, thereby realizing the transition between the closed state and the open state.

[0010] More preferably, the responsive stimulus includes at least one of light stimulation, thermal stimulation, or magnetic stimulation.

[0011] Preferably, for at least two layers of shielding structure, the projections of the support units in different layers of the shielding structure onto the glass substrate overlap.

[0012] More preferably, the shape memory materials used in the shielding units of the shielding structure in different layers have different glass transition temperatures.

[0013] Preferably, the shape memory polymer is at least one of polyurethane (meth) acrylate shape memory polymers, polycaprolactone acrylate shape memory polymers, polyethylene glycol acrylate shape memory polymers, epoxy-acrylate shape memory polymers, and phenolic resin-based shape memory polymers.

[0014] Preferably, the fluorinated photocurable monomer is perfluorooctyl ethyl acrylate.

[0015] Preferably, the color-developing functional material is at least one of cholesteric liquid crystal oligomers, thermochromic microcapsules, spiropyran, and perovskite materials.

[0016] Preferably, the nanomaterial is at least one of vanadium dioxide, titanium dioxide, silicon dioxide, antimony-doped tin oxide, aluminum oxide, and zirconium oxide.

[0017] Preferably, the radiation-resistant material is at least one of carbon nanotubes, graphene, graphite powder, azobenzene, and coumarin.

[0018] In a second aspect, the present invention provides a method for fabricating a 4D-printed shape memory smart porthole as described in the first aspect above, comprising: (1) The nano-functional material, the radiation-resistant material and the crosslinking agent are mixed to obtain a suspension; (2) The color-developing functional material, the fluorine-containing photocurable monomer, the shape memory polymer and the photoinitiator are added sequentially to the suspension and mixed under light-protected conditions to obtain the printing material; (3) The printing material is used to 4D print at least one layer of shielding structure; the shielding structure is composed of several parallel shielding modules, and the shielding module includes a support unit and a shielding unit; the middle region of the shielding unit is connected to the top of the support unit. (4) Integrate the at least one layer of shielding structure onto the glass substrate to obtain the 4D printed shape memory smart porthole.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The 4D-printed shape memory smart porthole provided by this invention integrates one or more shielding structures on a glass substrate as a shielding device, so as to achieve multi-level shape transformation by means of the shielding structure made of shape memory material to adapt to different light and magnetic field intensities in the space environment. Moreover, the shielding device can also present multiple colors as the temperature rises, so as to further improve the light blocking and heat protection performance. In addition, the shielding device also constructs a radiation intensity-responsive adaptive shielding mechanism, which effectively solves the problem of incompatibility between high radiation resistance and communication wave transmission in traditional aerospace porthole protective materials. Thus, the 4D-printed shape memory smart porthole integrates adaptive adjustment of light blocking, heat regulation and radiation resistance functions, meeting the application requirements of high reliability of light and heat protection, radiation protection and long-term stable service in complex space environments.

[0020] (2) The method for preparing the 4D printed shape memory smart porthole provided by the present invention utilizes 4D printing technology, which can not only achieve precise control of the structural size and morphological features of the porthole and meet the personalized customization needs of different application scenarios, but also has the advantages of fast forming speed, high processing efficiency and high manufacturing precision, and has good application prospects. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a 4D-printed shape memory smart porthole in the open state, according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a 4D-printed shape memory smart porthole in the closed state, according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a shielding module in an open state according to an embodiment of the present invention; Figure 4This is a schematic diagram of the structure of a shielding module in a closed state according to an embodiment of the present invention; Figure 5 This is a schematic diagram of another shielding module in a closed state according to an embodiment of the present invention; Figure 6 This is a schematic diagram of another 4D-printed shape memory smart porthole provided in an embodiment of the present invention; Reference numerals: 10-glass substrate; 20-shielding plate structure; 200-shielding module; 2001-support unit; 2002-shielding unit. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] The following is the concept of the present invention, such as Figure 1 , Figure 2 As shown, the present invention provides a 4D printed shape memory smart porthole, including at least one layer of shielding structure 20 placed on a glass substrate 10; the shielding structure 20 is composed of a plurality of parallel shielding modules 200, and the shielding module 200 includes a support unit 2001 and a shielding unit 2002; the middle region of the shielding unit 2002 is connected to the top of the support unit 2001. At least one layer of shielding structure 20 is integrally formed by 4D printing using shape memory material; The shielding unit 2002 includes a closed state and an open state; when all the shielding units 2002 in the shielding plate structure 20 are in the open state, the glass substrate 10 is covered. The shape memory material comprises the following components by mass fraction: 40%–55% shape memory polymer (e.g., 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, or 55%), 5%–10% fluorinated photocurable monomer (e.g., 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%), and 10%–18% crosslinking agent (e.g., 10%, 11%, 12%, 13%, 14%). %, 15%, 16%, 17% or 18%), color-developing functional materials 20% to 30% (e.g., 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%), nano-functional materials 1% to 3% (e.g., 1%, 1.5%, 2%, 2.5% or 3%), radiation-resistant materials 1% to 2% (e.g., 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8% or 2%), photoinitiator 1.5% to 3% (e.g., 1.5%, 2%, 2.5% or 3%).

[0025] In this embodiment of the invention, one or more shielding structures are integrated onto a glass substrate as a shielding device. The shielding structure, made of shape memory material, achieves multi-level shape transformation to adapt to varying light and magnetic field intensities in the space environment. Furthermore, the shielding device can display multiple colors as the temperature rises, further enhancing its light-blocking and heat protection performance. In addition, the shielding device incorporates a radiation-intensity-responsive adaptive shielding mechanism, effectively solving the problem of incompatibility between high radiation resistance and communication wave transmission in traditional aerospace window protective materials. Thus, the 4D-printed shape memory smart window integrates adaptive light-blocking, heat regulation, and radiation resistance functions, meeting the application requirements for highly reliable light and heat protection, radiation protection, and long-term stable service in complex space environments.

[0026] In this embodiment of the invention, the shape memory polymer, fluorinated photocurable monomer, and crosslinking agent in the shape memory material form a network through covalent crosslinking. This not only improves mechanical properties but also helps to fix nanomaterials and radiation-resistant materials within the polymer matrix, suppressing phase separation. The color-developing functional material endows the shape memory material with temperature-responsive visible light modulation capabilities, enabling multiple color changes in response to light, electricity, and magnetism, thereby altering the reflection characteristics of visible light of different wavelengths. This reduces the heating effect caused by visible light penetrating the window, allowing for further temperature control within the window. The addition of nanomaterials gives the shape memory material the characteristic of reflecting near-infrared light, thus reducing the heat transmitted by solar near-infrared radiation and achieving effective temperature control. The addition of radiation-resistant materials enables the shape memory material to achieve radiation shielding and energy dissipation, allowing it to be applied in space environments.

[0027] In the embodiments of this invention, experiments have confirmed that, with other component dosages remaining constant, if the amount of shape memory polymer is less than 40 wt%, it leads to insufficient matrix support, decreased shape memory fixation rate, and reduced mechanical properties; however, if its dosage is greater than 55 wt%, it results in high system viscosity, making it difficult to fully disperse other functional fillers and hindering printing. With other component dosages remaining constant, if the content of the color-developing functional material is less than 20 wt%, the system exhibits weak color change and a reduced response range; however, if the component content is greater than 30 wt%, the color-developing functional material is prone to self-aggregation, leading to increased interfacial repulsion and uneven color change. With other component dosages remaining constant, if the amount of crosslinking agent is less than 10 wt%, it results in insufficient crosslinking, a fragile structure, and reduced shape memory efficiency; however, if its dosage is greater than 18 wt%, it leads to excessive crosslinking, making it difficult to disperse functional fillers and limiting deformation. With other component dosages remaining constant, if the content of the fluorinated photocurable monomer is less than 5 wt%, it results in high system viscosity, making the functional fillers prone to agglomeration; however, if the content of this component is greater than 10 wt%, it leads to decreased mechanical properties and higher brittleness of the shape memory material. With other components remaining constant, a nanomaterial content below 1 wt% results in weak thermal insulation and light regulation functions; a content above 3 wt% leads to severe agglomeration and uneven thermal insulation and light regulation functions. With other components remaining constant, a radiation-resistant material content that is too low (<1 wt%) results in insufficient photothermal and magnetocaloric conversion capabilities; however, a content that is too high (>2 wt%) causes severe agglomeration. With other components remaining constant, a photoinitiator content that is too low (<1.5 wt%) leads to insufficient curing of shape memory materials and a decrease in shape fixation rate; however, a content that is too high (>3 wt%) leads to excessive light absorption, excessively rapid curing, and high internal stress.

[0028] In some preferred embodiments, such as Figure 3 As shown, when the blocking unit is in the open state, the angle formed between the blocking unit and the supporting unit is 90°. like Figure 4 and Figure 5 As shown, when the blocking unit is in the closed state, the angle formed between the blocking unit and the supporting unit is less than 90° (for example, it can be 60°, 45° or 30°, etc.).

[0029] It should be noted that the support unit is used to support the occlusion unit. Specifically, the shape memory material can be designed to have multiple glass transition temperatures, so that the fabricated 4D-printed shape memory smart porthole can have multiple closing states, achieving different degrees of closure under different stimulus conditions or intensities. For example, under low light or electromagnetic stimulus intensities, the occlusion unit... Figure 5 The closed state is shown; under high intensity of light, electromagnetic, or other stimuli, the blocking unit is in a closed state. Figure 4 The closed state shown achieves light shielding and radiation protection; under high light, electromagnetic, and other stimuli, the shielding unit extends... Figure 3 The shown open state further enhances the light-shielding and radiation protection effects. To ensure the support capacity of the support unit, its shape memory properties were not utilized.

[0030] In some preferred embodiments, such as Figure 1 As shown, when all the blocking units are in the open state, at least one side of the blocking unit extends outward in the horizontal direction to form an extended blocking area.

[0031] Specifically, when the blocking unit is in the open state, it includes, but is not limited to, the following two situations: the first situation, such as... Figure 1 As shown, when the blocking unit is in the open state, both sides of the blocking unit extend outward in the horizontal direction to form an extended blocking area; in the second case, when the blocking unit is in the open state, one side of the blocking unit extends outward in the horizontal direction to form an extended blocking area.

[0032] In some more preferred embodiments, such as Figure 1 As shown, when all the shielding units in the shielding structure are in the open state, adjacent extended shielding areas are connected in sequence to completely cover the glass substrate.

[0033] Specifically, when all the shielding units in the shielding plate structure are in the open state, the extended shielding areas of adjacent shielding units are connected in sequence, that is, the width of the shielding unit in the open state is basically the same as the distance between adjacent support units.

[0034] In some preferred embodiments, the blocking unit heats up to the glass transition temperature of the shape memory material and deforms after being stimulated, thereby achieving the transition between a closed state and an open state.

[0035] In some preferred embodiments, the responsive stimulus includes at least one of light stimulation, thermal stimulation, or magnetic stimulation.

[0036] In some preferred embodiments, such as Figure 6 As shown, for at least two layers of shielding structure, the projections of the support units in different layers of shielding structure onto the glass substrate overlap. That is, the coordinates of the support units in each layer of shielding structure are the same in the horizontal plane, and only their coordinates in the height direction are different.

[0037] In some preferred embodiments, the shape memory materials used in the shielding units of the shielding structure of different layers have different glass transition temperatures.

[0038] In this embodiment of the invention, by giving different layers of shielding structure different glass transition temperatures, the shielding structure of different layers can be deformed under different conditions, so as to realize the layer-by-layer deformation and independent deformation of each shielding structure, so that each layer of shielding structure can be in an open or closed state as needed, further improving the light-blocking and heat-insulating capabilities of 4D printed shape memory smart porthole.

[0039] In some preferred embodiments, the shape memory polymer is at least one of polyurethane (meth) acrylate shape memory polymers, polycaprolactone acrylate shape memory polymers, polyethylene glycol acrylate shape memory polymers, epoxy-acrylate shape memory polymers, and phenolic resin-based shape memory polymers.

[0040] It should be noted that "at least one" means any one or more of them mixed in any proportion.

[0041] In some preferred embodiments, the fluorinated photocurable monomer is perfluorooctyl ethyl acrylate, CAS number 27905-45-9.

[0042] In this embodiment of the invention, perfluorooctyl ethyl acrylate has low surface energy properties and can also reduce the repulsion and aggregation tendency of the organic / inorganic interfaces of the components of the shape memory material.

[0043] In some preferred embodiments, the color-developing functional material is at least one of cholesteric liquid crystal oligomers, thermochromic microcapsules, spiropyran, and perovskite materials.

[0044] In some preferred embodiments, the nanomaterial is at least one of vanadium dioxide, titanium dioxide, silicon dioxide, antimony-doped tin oxide, aluminum oxide, and zirconium oxide.

[0045] In some preferred embodiments, the radiation-resistant material is at least one of carbon nanotubes, graphene, graphite powder, azobenzene, and coumarin.

[0046] In some preferred embodiments, the shape memory material comprises, by mass fraction, the following components: 40%–55% polyurethane (meth)acrylate shape memory polymer, 5%–10% perfluorooctyl ethyl acrylate, 10%–18% polyethylene glycol diacrylate, 20%–30% cholesteric liquid crystal oligomer, 1%–3% nanofunctional material, 1%–2% carbon nanotubes, and 1.5%–3% 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO photoinitiator).

[0047] In this embodiment of the invention, carbon nanotubes can form a supporting network around cholesteric liquid crystal oligomers and nanofunctional materials, inhibiting the self-aggregation of cholesteric liquid crystal oligomers and the aggregation of nanofunctional materials, while also improving photothermal conductivity and making the thermal response of nanofunctional materials uniform. Perfluorooctyl ethyl acrylate can reduce the repulsion and aggregation tendency of organic / inorganic interfaces; polyurethane (meth)acrylate shape memory polymer, cholesteric liquid crystal oligomers and polyethylene glycol diacrylate form a network through covalent crosslinking, which not only improves mechanical properties, but also helps to fix nanofunctional materials and carbon nanotubes in the polymer matrix, further inhibiting phase separation. Moreover, the composite of nanofunctional materials and carbon nanotubes can form a synergistic coupling mechanism, and the heterogeneous interface between nanofunctional materials and carbon nanotubes can induce significant interfacial polarization and multiple scattering effects, further improving radiation attenuation efficiency. In addition, the thermally conductive network constructed by carbon nanotubes and the thermal response characteristics of nanofunctional materials work synergistically to effectively alleviate local heat accumulation and improve the thermal stability of the system.

[0048] In a second aspect, the present invention provides a method for fabricating a 4D-printed shape memory smart porthole as described in the first aspect above, comprising: (1) The nano-functional material, the radiation-resistant material and the crosslinking agent are mixed to obtain a suspension; (2) Add color-developing functional material, fluorine-containing photocurable monomer, shape memory polymer and photoinitiator to the suspension in sequence and mix them under light-protected conditions to obtain printing material; (3) The printing material is used to 4D print at least one layer of shielding structure; the shielding structure is composed of several parallel shielding modules, the shielding module includes a support unit and a shielding unit; the middle area of ​​the shielding unit is connected to the top of the support unit. (4) Integrate at least one layer of shielding structure on the glass substrate to obtain a 4D printed shape memory smart porthole.

[0049] It should be noted that in step (3), at least one layer of shielding structure is constructed by printing and curing layer by layer under ultraviolet light irradiation. During the printing process, the printing material undergoes a rapid cross-linking reaction under the action of the photoinitiator, forming a stable three-dimensional cross-linked network between each printing layer. Step (4) includes, but is not limited to, using a highly adhesive adhesive with excellent radiation resistance to integrate at least one layer of shielding structure onto the glass substrate.

[0050] In this embodiment of the invention, the color-developing functional materials, nano-functional materials, and radiation-resistant materials are prone to agglomeration, which can affect the uniform configuration of the printing material. Therefore, this aspect employs a staged addition and dispersion strategy. First, the nano-functional materials, radiation-resistant materials, and crosslinking agents are ultrasonically dispersed to form a stable suspension. Then, the color-developing functional materials are added in stages and stirred to ensure uniform dispersion. Subsequently, a fluorine-containing photocurable monomer is added to improve interfacial compatibility through fluorine-fluorine or fluorine-organic interactions, reducing the agglomeration of the color-developing functional materials or nano-functional materials. Next, a shape memory polymer is added. Due to its high viscosity, adding it later can encapsulate the well-dispersed functional components while avoiding nanoparticle agglomeration caused by stirring the high-viscosity system. Finally, a photoinitiator is added to ensure uniform photocuring without affecting the initial dispersion.

[0051] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these embodiments. The present invention may have many other embodiments, and those skilled in the art can make various corresponding changes and modifications based on the present invention without departing from its spirit and essence. However, all such corresponding changes and modifications should fall within the scope of protection of the appended claims. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials, reagents, etc., used in the following embodiments can be obtained commercially or by existing methods.

[0052] All components in the following examples and comparative examples are by mass parts, and polyethylene glycol diacrylate (PEGDA) is in liquid state.

[0053] Polycaprolactone-based polyurethane acrylate shape memory polymers are obtained as follows: Polycaprolactone diol (PCL diol, Mn=1000) is dried at 80°C under vacuum for 4-6 hours to fully remove moisture and avoid side reactions between isocyanate groups and water. Subsequently, under dry, light-protected reaction conditions with nitrogen purging, the pretreated PCL diol is added to a reactor, the temperature is raised to 70-75°C, and 4,4'-diphenylmethane diisocyanate (MDI) is slowly added dropwise, while 0.03-0.05 wt% of dibutyltin dilaurate (DBTDL) is added as a catalyst. The reaction is continued at this temperature with stirring for 4-8 hours to allow the PCL diol and MDI to react fully, generating isocyanate-terminated polyurethane prepolymers. The reaction system was then slowly cooled to 30-35°C, and hydroxyethyl methacrylate (HEMA) was added. The mixture was stirred for 1.5-2 hours to allow HEMA to cap the isocyanate groups at the ends of the prepolymer until the -NCO groups in the system completely disappeared, yielding a polycaprolactone-type polyurethane acrylate shape memory polymer. The molar ratio of PCL glycol, MDI, and HEMA was 1:2:2.

[0054] The polyurethane acrylate shape memory polymer was obtained as follows: Polyethylene glycol was placed in a vacuum drying oven and dried at 80-100°C for 2-4 hours to remove moisture. Then, pretreated polyethylene glycol (PEG) was added to a reactor equipped with a stirrer and nitrogen protection. Under nitrogen protection, the temperature was raised to 65-75°C, and MDI was slowly added, along with a small amount of catalyst DBTDL. The system temperature was controlled at 70-80°C, and the reaction was continuously stirred for 2-4 hours to ensure complete reaction between the hydroxyl groups of PEG and the isocyanate groups of MDI. The reaction system was then cooled to 50-60°C, HEMA was added, and the reaction was continued with stirring for 3-5 hours until the NCO groups were completely reacted, yielding the polyurethane acrylate shape memory polymer. The molar ratio of PEG, MDI, and HEMA was 1:2:2.

[0055] Cholesteric liquid crystal oligomers were obtained as follows: 20-25 parts of nematic liquid crystal monomer 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), 1-1.5 parts of chiral dopant LC756, 0.2-0.3 parts of catalyst dimethylaminopropylamine diisopropanol (DPA), and 65-70 parts of solvent dichloromethane (DCM) were sequentially added to a reaction vessel and stirred at room temperature for 5 min to ensure uniform dispersion of the liquid crystal monomer, chiral dopant, and catalyst in the solvent. Subsequently, 10-15 parts of chain extender 2,2′-(1,2-ethylenedioxydioxo)diethylthiol (EDDET) were added to the above system, and the reaction system was heated to 55°C and stirred continuously for 5-7 h, allowing the liquid crystal monomer and chain extender to gradually form a liquid crystal oligomer with cholesteric phase structural characteristics under the action of the catalyst. After the reaction was completed, the system temperature was kept at 55°C, and the dichloromethane solvent was evaporated and removed until the sample gradually changed from a fluid state to a white viscous substance, thus obtaining the cholesteric phase liquid crystal oligomer.

[0056] Example 1 A 4D-printed shape memory smart porthole, such as Figure 1 and Figure 2 As shown, it includes at least one layer of shielding structure 20 placed on a glass substrate 10; the shielding structure 20 is composed of a plurality of shielding modules 200 arranged in parallel, and the shielding module 200 includes a support unit 2001 and a shielding unit 2002; the middle region of the shielding unit 2002 is connected to the top of the support unit 2001. At least one layer of shielding structure 20 is integrally formed by 4D printing using shape memory material; The blocking unit 2002 includes two closed states (such as...) Figure 4 and Figure 5 (as shown) and on / off state (as shown) Figure 3 (As shown); when all the shielding units 2002 in the shielding structure 20 are in the open state, the two sides of the shielding unit extend outward in the horizontal direction to form an extended shielding area. Adjacent extended shielding areas are connected in sequence to completely cover the glass substrate 10. A method for fabricating a 4D-printed shape memory smart porthole includes: (1) Two parts of nano-sized vanadium dioxide, 1.5 parts of carbon nanotubes and 11.5 parts of polyethylene glycol diacrylate (PEGDA) were ultrasonically dispersed and mixed to obtain a suspension; (2) Add 25 parts of cholesteric liquid crystal oligomer, 8 parts of perfluorooctyl ethyl acrylate, 50 parts of polycaprolactone-type polyurethane acrylate shape memory polymer and 2 parts of TPO photoinitiator to the suspension in sequence and mix them under light-protected conditions to obtain the printing material. (3) Under ultraviolet light irradiation, the printing material is printed using 4D printing by means of layer-by-layer printing exposure curing. Figure 1 and Figure 2 The structure shown is a single-layer shielding plate. (4) Integrate a layer of shielding structure onto the glass substrate to obtain a 4D printed shape memory smart porthole.

[0057] Application: Applying external force to the baffle structure at a temperature of 110~120℃ changes it from an open state to a closed state, resulting in programmed shape 1 (e.g., ...). Figure 4 (As shown); then, while maintaining the external force, the temperature is lowered to 80~90℃ to fix the baffle structure in programmed shape 1. Afterwards, the external force is continued to be applied at 80~90℃, causing the baffle structure to be further programmed from programmed shape 1 to a closed state, resulting in programmed shape 2 (as shown). Figure 5 (as shown); then the temperature is lowered to room temperature, thereby fixing the shield structure to the programmed shape 2.

[0058] Example 2 Example 2 is basically the same as Example 1, except that: the 4D printed shape memory smart porthole is as follows: Figure 6 As shown.

[0059] Specifically, the 4D-printed shape memory smart porthole includes two layers of shielding structure 20 placed on a glass substrate 10; the projections of the support units in the different layers of shielding structure on the glass substrate overlap.

[0060] Example 3 Example 3 is basically the same as Example 1, except that the shape memory material is different.

[0061] Specifically, the shape memory material comprises the following components by mass fraction: 50% polyurethane acrylate shape memory polymer, 8% perfluorooctyl ethyl acrylate, 11.5% polyethylene glycol diacrylate, 25% cholesteric liquid crystal oligomer, 2% silica, 1.5% graphene, and 2%, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO photoinitiator).

[0062] Example 4 Example 4 is basically the same as Example 1, except that the shape memory material is different.

[0063] Specifically, the shape memory material comprises the following components by mass fraction: 40% polycaprolactone-type polyurethane acrylate shape memory polymer, 10% perfluorooctyl ethyl acrylate, 16.5% polyethylene glycol diacrylate, 30% cholesteric liquid crystal oligomer, 1% vanadium dioxide, 1% carbon nanotubes, and 1.5% 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO photoinitiator).

[0064] Example 5 Example 4 is basically the same as Example 1, except that the shape memory material is different.

[0065] Specifically, the shape memory material comprises the following components by mass fraction: 55% polycaprolactone-type polyurethane acrylate shape memory polymer, 5% perfluorooctyl ethyl acrylate, 10% polyethylene glycol diacrylate, 22% cholesteric liquid crystal oligomer, 3% vanadium dioxide, 2% carbon nanotubes, and 3% 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO photoinitiator).

[0066] Comparative Example 1 Comparative Example 1 is basically the same as Example 1, except that the shape memory material is different.

[0067] Specifically, only 35 parts of polycaprolactone-type polyurethane acrylate shape memory polymer were added to the shape memory material.

[0068] Comparative Example 2 Comparative Example 2 is basically the same as Example 1, except that the shape memory material is different.

[0069] Specifically, no carbon nanotubes were added to the shape memory material.

[0070] Comparative Example 3 Comparative Example 3 is basically the same as Example 1, except that the shape memory material is different.

[0071] Specifically, vanadium dioxide was not added to the shape memory material.

[0072] Tests showed that the 4D-printed shape memory smart windows prepared in the above embodiments all possess shape memory function and integrate adaptive adjustment of light-blocking, thermal regulation, and radiation resistance. They also achieve multiple color changes in response to stimuli such as light, electricity, and magnetism. However, in Comparative Example 1, the addition of too little shape memory polymer resulted in insufficient support from the shape memory polymer matrix, leading to a decrease in shape memory fixation rate. In Comparative Examples 2 and 3, the lack of a synergistic coupling mechanism between the vanadium dioxide and carbon nanotubes, and the absence of a heterogeneous interface dependent on them, prevented the induction of significant interfacial polarization and multiple scattering effects. Consequently, the resulting 4D-printed shape memory smart windows exhibited poor radiation resistance and low thermal stability.

[0073] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A 4D-printed shape memory smart porthole, characterized in that, The invention includes at least one layer of shielding structure placed on a glass substrate; the shielding structure is composed of several parallel shielding modules, each shielding module including a support unit and a shielding unit; the middle region of the shielding unit is connected to the top of the support unit; The at least one layer of shielding structure is integrally formed by 4D printing using shape memory material; The shielding unit includes a closed state and an open state; when all the shielding units in the shielding plate structure are in the open state, the glass substrate is covered. The shape memory material comprises the following components by mass fraction: 40%~55% shape memory polymer, 5%~10% fluorine-containing photocurable monomer, 10%~18% crosslinking agent, 20%~30% color-developing functional material, 1%~3% nano-functional material, 1%~2% radiation-resistant material, and 1.5%~3% photoinitiator.

2. The 4D-printed shape memory smart porthole according to claim 1, characterized in that, When the shielding unit is in a closed state, the angle formed between the shielding unit and the supporting unit is less than 90°; When the shielding unit is in the open state, the angle between the shielding unit and the supporting unit is 90°.

3. The 4D-printed shape memory smart porthole according to claim 1, characterized in that, When all the shielding units are in the open state, at least one side of the shielding unit extends outward in the horizontal direction to form an extended shielding area; preferably, when all the shielding units in the shielding plate structure are in the open state, adjacent extended shielding areas are connected in sequence.

4. The 4D-printed shape memory smart porthole according to claim 1, characterized in that, The occlusion unit heats up to the glass transition temperature of the shape memory material and deforms after being stimulated, thereby changing between the closed state and the open state; preferably, the stimuli include at least one of light stimulation, thermal stimulation or magnetic stimulation.

5. The 4D-printed shape memory smart porthole according to claim 1, characterized in that, For at least two-layer shielding structures, the projections of the supporting units in different layers of the shielding structure onto the glass substrate overlap; preferably, the shape memory materials used by the shielding units in different layers of the shielding structure have different glass transition temperatures.

6. The 4D-printed shape memory smart porthole according to claim 1, characterized in that, The shape memory polymer is at least one of polyurethane (meth)acrylate shape memory polymers, polycaprolactone acrylate shape memory polymers, polyethylene glycol acrylate shape memory polymers, epoxy-acrylate shape memory polymers, and phenolic resin-based shape memory polymers; and / or, The fluorinated photocurable monomer is perfluorooctyl ethyl acrylate.

7. The 4D-printed shape memory smart porthole according to claim 1, characterized in that, The color-developing functional material is at least one of cholesteric liquid crystal oligomers, thermochromic microcapsules, spiropyran, and perovskite materials.

8. The 4D-printed shape memory smart porthole according to claim 1, characterized in that, The nanomaterial is at least one of vanadium dioxide, titanium dioxide, silicon dioxide, antimony-doped tin oxide, aluminum oxide, and zirconium oxide.

9. The 4D-printed shape memory smart porthole according to any one of claims 1 to 8, characterized in that, The radiation-resistant material is at least one of carbon nanotubes, graphene, graphite powder, azobenzene, and coumarin.

10. A method for fabricating a 4D-printed shape memory smart porthole as described in any one of claims 1 to 9, characterized in that, include: (1) The nano-functional material, the radiation-resistant material and the crosslinking agent are mixed to obtain a suspension; (2) The color-developing functional material, the fluorine-containing photocurable monomer, the shape memory polymer and the photoinitiator are added sequentially to the suspension and mixed under light-protected conditions to obtain the printing material; (3) The printing material is used to 4D print at least one layer of shielding structure; The shielding structure consists of several parallel shielding modules, each shielding module including a support unit and a shielding unit; the middle region of the shielding unit is connected to the top of the support unit. (4) Integrate the at least one layer of shielding structure onto the glass substrate to obtain the 4D printed shape memory smart porthole.

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