High-elasticity self-repairing mechanical color-changing ionic gel film and preparation method thereof

Abstract

The application discloses a mechanical color-changing ionic gel film with high elasticity and self-repairing characteristics and a preparation method thereof, and belongs to the field of new material preparation. The mechanical color-changing ionic gel film is obtained by embedding a sub-micron microsphere three-dimensional ordered array into a double-layer homogeneous ionic gel layer based on an ion polymer. The ordered array of the non-close-packed microspheres changes the lattice spacing when stressed, achieving the colorimetric sensing effect of tensile / compressive color change. Non-covalent interaction weak ionic acrylate monomers are selected for photopolymerization, dynamic acylhydrazone bonds are introduced as reversible chemical cross-linking to construct a polymer network, and a high content of compatible ionic liquid is doped, so that the high elasticity and self-healing properties are realized. The mechanical sensing, motion detection, flexible display, interactive device and the like have wide application prospects.

Description

Technical Field

[0001] This invention belongs to the field of new material preparation, specifically to the field of structural color materials, and specifically relates to a highly elastic self-healing mechanical color-changing ionogel membrane and its preparation method. Technical Background

[0002] The optical signals of mechanically responsive colors can visualize invisible stresses in materials, enabling colorimetric sensing of mechanical stimuli such as tension, compression, or bending. Color-changing methods include pigment color and structural color. Structural colors are generated through the interference and diffraction of light with ordered micro / nano structures. Compared to pigment colors, structural colors are independent of molecular structure and possess excellent chemical stability and resistance to photobleaching.

[0003] With the development of flexible electronics, it is essential to develop mechanochromic materials that possess both synchronous electrical response and mechanical color change. Composite materials obtained by introducing structural color into conductive hydrogels and conductive elastomers can achieve synergistic optical and electromechanical sensing by adjusting structural parameters through external forces. However, hydrogels cannot overcome the defects of freezing and dehydration, resulting in poor environmental resistance, while elastomers have poor conductivity, limiting the promotion and practical application of optoelectronic dual-signal mechanoresponsive materials.

[0004] Iongels, composed of polymer networks and ionic liquids, possess high conductivity, customizable mechanical properties, and excellent environmental resistance. However, numerous non-covalent interactions reduce the elasticity of iongels, leading to significant strength loss and residual strain under repeated loading, severely impacting the reliability of sensing signals. Self-healing properties can restore the optical and electrical sensing performance of damaged iongels, extending their lifespan. Therefore, developing photoelectric dual-response mechanosensitive iongels with both high elasticity and self-healing properties is of great significance. Summary of the Invention

[0005] To address the shortcomings of current mechanochromic sensing materials, this invention aims to provide a highly elastic, self-healing mechanochromic ionogel membrane and its preparation method, achieving a dual optical and electrical response to strain. An ionic polymer network undergoes reversible chemical cross-linking via dynamic acylhydrazone bonds and encapsulates a high content of ionic liquid, exhibiting excellent elasticity and self-healing properties. The mechanical properties of the ionogel can be controlled by varying the amount of cross-linking agent components (diacetone acrylamide and diacylhydrazine compounds) and the ionic liquid content. A non-close-packed microsphere array endows the ionogel with highly sensitive, wide-range mechanochromic properties, outputting synergistic optical and electrical signals in response to different tensile / compressive strains. The prepared ionogel exhibits excellent environmental stability and long-term durability, showing great promise for applications in flexible sensors, smart displays, visual interactive devices, and biomimetic artificial skin.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A highly elastic, self-healing, mechanically color-changing ionogel membrane is provided, in which a non-densely packed ordered microsphere array is embedded in a bilayer ionogel membrane obtained by photopolymerization of ionic acrylic acid or acrylate monomers. The ionogel membrane is chemically cross-linked by forming reversible hydrazone bonds through the reaction of diacetone acrylamide and diacylhydrazine compounds, and encapsulates 50%-75% by mass of ionic liquid.

[0008] The microspheres are silica microspheres or core-shell structured microspheres with silica as the shell. The core-shell structured microspheres are one of the following: silica-coated polystyrene core-shell microspheres, silica-coated titanium dioxide core-shell microspheres, silica-coated cerium dioxide core-shell microspheres, silica-coated zinc sulfide core-shell microspheres, silica-coated polymethyl methacrylate core-shell microspheres, and silica-coated zinc oxide core-shell microspheres. The shell thickness of the core-shell structured microspheres is 10–25 nm. The microspheres are not limited to those prepared above.

[0009] The ionic acrylic or acrylate monomer is one or more of the following: cationic acrylic or acrylate monomers, anionic acrylic or acrylate monomers, and zwitterionic acrylic or acrylate monomers.

[0010] According to the above technical solution, in a preferred embodiment, the diameter of the microspheres is 160–220 nm, and the thickness of the opal template is 5–10 μm.

[0011] According to the above technical solution, in a preferred embodiment, the non-densely packed ordered microsphere array is obtained by swelling a densely packed ordered microsphere array.

[0012] According to the above technical solution, in a preferred embodiment, the gaps in the densely packed ordered microsphere array are filled with ionogel to form a composite structure. In this composite structure, the ionogel swells after being dissolved by the mixed liquid, resulting in an increase in the spacing between the microspheres, thus obtaining a non-densely packed ordered microsphere array.

[0013] According to the above technical solution, in a preferred embodiment, the densely packed ordered microsphere array is obtained by convective self-assembly.

[0014] According to the above technical solution, in a preferred embodiment, the ionic acrylic acid or acrylate monomer is one or more of the following: cationic acrylic acid or acrylate monomers (e.g., acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride), anionic acrylic acid or acrylate monomers (e.g., acrylic acid), and zwitterionic acrylic acid or acrylate monomers (e.g., sulfobetaine methacrylate).

[0015] According to the above technical solution, in a preferred embodiment, the ionic liquid should be selected to satisfy the requirements of photopolymerization of a mixture of ionic acrylate monomers, diacetone acrylamide, diacylhydrazine, ionic liquid and photoinitiator, resulting in a colorless and transparent ionic gel film without microsphere arrays. The ionic liquid is one or more of tetrafluoroborate, hexafluorophosphate, onium malononitrile salt, and bis(trifluoromethanesulfonyl)imide salt.

[0016] The present invention also provides a method for preparing the above-mentioned highly elastic self-healing mechanical color-changing ionogel membrane, comprising the following steps:

[0017] ① At room temperature, a microsphere dispersion with a mass fraction of 5-10% is coated on a hydrophobic substrate. After the solvent has completely evaporated, the microspheres self-assemble to form an opal photonic crystal template.

[0018] ② Adhere commercial polyimide tape to both ends of a hydrophobic substrate assembled with an opal photonic crystal template, cover with a transparent substrate, and inject a mixture of ionic acrylic or acrylate monomers, diacetone acrylamide, diacylhydrazine compounds, ionic liquids and photoinitiators between the two substrates. Polymerize with ultraviolet light at a power of 10-20W for 1-2 hours to obtain a composite film.

[0019] ③ Peel the composite membrane obtained in step ② from the hydrophobic substrate and flip it so that the microsphere array faces upward and the ionogel matrix faces downward. Attach polyimide tape to both ends of the substrate, cover with a transparent substrate, and pour a mixture of ionic acrylic or acrylate monomers, diacetone acrylamide, diacylhydrazine compounds, ionic liquids, and photoinitiators used in step ② between the two substrates. Polymerize with ultraviolet light at a power of 10-20W for 1-2 hours. After completely peeling it off from the substrate, a highly elastic self-healing mechanical color-changing ionogel membrane is obtained.

[0020] According to the above technical solution, in a preferred embodiment, in step ①, the hydrophobic substrate is one of polymethyl methacrylate sheet, polytetrafluoroethylene sheet, or a flat sheet with commercially available transparent polypropylene tape.

[0021] According to the above technical solution, in the preferred case, in step ①, the coating amount of the microsphere dispersion is 100-200 microliters per square centimeter.

[0022] According to the above technical solution, in a preferred embodiment, ethanol is used as the solvent for the microsphere dispersion.

[0023] According to the above technical solution, in a preferred embodiment, the planar area of ​​the hydrophobic substrate used is 1×1cm. 2 Up to 10×10cm 2 The thickness is 2-5mm. It is not limited to the above dimensions.

[0024] According to the above technical solution, in a preferred embodiment, the thickness of the polyimide tape is 200–1000 μm.

[0025] According to the above technical solution, in a preferred embodiment, the transparent substrate is one of polymethyl methacrylate sheet, glass sheet, or a flat transparent sheet with polypropylene tape.

[0026] According to the above technical solution, in a preferred embodiment, the diacylhydrazine compound is one or more of succinic diacylhydrazine, adipic diacylhydrazine, oxaloyl diacylhydrazine, maleic diacylhydrazine, and 3,3'-dithiobis(propionylhydrazine). It is not limited to the diacylhydrazine compounds mentioned above.

[0027] According to the above technical solution, in a preferred embodiment, the photoinitiator is one of 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, and 1-hydroxycyclohexylphenylpropanone. The ultraviolet polymerization conditions are: power 10-20W and polymerization time 1-2 hours.

[0028] According to the above technical solution, in a preferred embodiment, the mass ratio of the ionic acrylic acid or acrylate monomer to diacetone acrylamide is 100:1 to 100:4, the molar ratio of diacetone acrylamide to dihydrazide compound is 2:1 to 5:1, the mass ratio of the ionic acrylic acid or acrylate monomer to ionic liquid is 1:1 to 1:3, and the mass ratio of the ionic acrylic acid or acrylate monomer to photoinitiator is 100:0.5 to 100:2.

[0029] According to the above technical solution, in a preferred embodiment, if the ionic acrylic acid or acrylate monomers exist in solution form, after UV polymerization and complete peeling from the substrate in step ③, the solvent needs to be dried by heating at a temperature of 50–100°C. The mass fraction of the ionic acrylate monomer solution is 50–100%.

[0030] Another objective of this invention is to provide an application of a highly elastic, self-healing, mechanochromic ionogel membrane, which has broad application prospects in fields such as human motion detection, pressure imaging, interactive sensing, and intelligent human-machine interfaces. Traditional mechanochromic sensing materials can only output a single optical signal, which cannot meet the electrical signal requirements of flexible electronic ionization, limiting practical applications. The developed mechanochromic ionogel possesses excellent electrical properties, responding to different strains through changes in resistance with high sensitivity, eliminating the need for complex signal processing equipment. Thanks to the introduction of a non-close-packed microsphere array, the lattice spacing can be changed during stretching and compression, generating a sensitive and intuitive dynamic structural color signal, providing immediate visual feedback, which can be used for human motion detection and dynamic pressure imaging. Existing ionogels have not yet simultaneously achieved high elasticity and self-healing properties. This invention introduces dynamic acylhydrazone bonds into an ionic polymer network as a reversible chemical crosslink, achieving a balance and integration of elasticity and self-healing properties, which is beneficial for long-term stable use and cost reduction. Through the integration of multiple ionogel arrays, it has application potential in the fields of human-machine interfaces and interactive sensing. Applications are not limited to these.

[0031] The mechanochromic ionogel membrane of this invention is obtained by embedding a three-dimensional ordered array of submicron microspheres into a bilayer homogeneous ionogel layer based on an ionomer. The non-close-packed ordered array of microspheres exhibits a change in lattice spacing under stress, achieving a colorimetric sensing effect of tensile / compression-induced color change. Photopolymerization is performed using ionic acrylic or acrylate monomers with weak non-covalent interactions, introducing dynamic acylhydrazone bonds as reversible chemical crosslinks to construct the polymer network. Furthermore, a high content of compatible ionic liquid is incorporated, simultaneously achieving high elasticity and self-healing properties.

[0032] The advantages of this invention are as follows: the highly elastic, self-healing, mechanochromic ionogel membrane is highly practical and versatile. The preparation method is simple, and the resulting mechanochromic ionogel membrane possesses excellent electrical and mechanical properties, a bright structural color, and can sensitively respond to tensile and compressive strain, achieving coordinated output of electrical and optical signals. High elasticity and self-healing properties ensure signal reliability during long-term use, extend service life, and reduce maintenance costs. The stable chemical cross-linking structure enables the ionogel membrane to exhibit stable electrical and optical responses after multiple uses, demonstrating excellent cycle durability. This invention has broad application prospects in fields such as novel flexible sensors, intelligent displays, visual interactive devices, and bionic artificial skin. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the preparation of the highly elastic self-healing mechanical color-changing ionogel membrane in Example 1, and it is also applicable to all examples.

[0034] Figure 2a is an SEM image of the silica-coated polystyrene microsphere template used in Example 1. Figure 2 b is a SEM image of the cross-section of the highly elastic, self-healing, mechanically color-changing ionogel membrane. Figure 2 c is Figure 2 A magnified view of part b. The silica-coated polystyrene microspheres have a particle size of ~210 nm. The microspheres in the opal template are arranged in an orderly face-centered cubic packing. After being filled with ionomer gel to form a composite film, the microsphere array changes from close packing to non-close packing but still maintains an orderly arrangement.

[0035] Figure 3 a is a digital photograph of the highly elastic self-healing mechanochromic ionogel membrane obtained in Example 1 under different tensile strains. Figure 3 b represents the corresponding reflectance spectrum; Figure 3 c represents digital photographs taken under different compressive strains. Figure 3 d represents the corresponding reflection spectrum. The wavelength shift range for stretch-induced color change is >130nm, and for compression-induced color change is >170nm. The structural color is sensitive to strain changes.

[0036] Figure 4 The stress-strain curve of the highly elastic self-healing mechanochromic ionogel membrane obtained in Example 1 during 200 consecutive stretch-relaxation cycles shows only <5% residual strain and very low strength loss, indicating high elasticity.

[0037] Figure 5 a represents the electrical response signal of the highly elastic self-healing mechanochromic ionogel membrane obtained in Example 1 to different tensile strains. Figure 5 b represents the electrical response signal to different compressive strains. Electrical signals can accurately reflect strain and have high sensitivity.

[0038] Figure 6 The images show the reflection spectra of the highly elastic self-healing mechanochromic ionogel membranes obtained in Examples 1, 4, and 5 in their relaxed state. As the particle size of the silica-coated polystyrene microspheres increases, the reflection wavelength of the resulting highly elastic self-healing mechanochromic ionogel membrane in its relaxed state also increases.

[0039] Figure 7 The stress-strain curves are for the highly elastic self-healing, mechanically color-changing ionogel membranes obtained in Examples 1, 7, and 8. With increasing crosslinking component content, the tensile modulus increases and the fracture strain decreases. With increasing ionic liquid content, the tensile modulus decreases and the fracture strain increases.

[0040] Figure 8 These are photographs of the highly elastic self-healing, mechanically color-changing ionogel membrane obtained in Example 1 after damage and self-healing, exhibiting stretching and color change. The cracks are clearly visible under slight stretching after damage; after self-healing, it can be stretched from red to blue without showing any gaps.

[0041] Figure 9 The image shows the changes in optical signal (reflection wavelength) of the highly elastic self-healing mechanical color-changing ionogel membrane obtained in Example 1 during 1000 compressions and stretches, demonstrating its good cycle durability.

[0042] Figure 10 The changes in electrical signals of the highly elastic self-healing mechanochromic ionogel membrane obtained in Example 1 during 1000 compression and stretching cycles demonstrate its good cycle durability.

[0043] Figure 11 The stress-strain curves are shown for the ionogels obtained in Examples 10 and 12. Due to the absence of simultaneous addition of adipic acid dihydrazide and diacetone acrylamide, the ionogels exhibit extremely low mechanical strength.

[0044] Figure 12 This is a digital photograph of the ionogel obtained in Example 11. When only adipic acid dihydrazide is added without diacetone acrylamide, the resulting ionogel has very poor film-forming properties and cannot form independent films.

[0045] Figure 13 The images show partial infrared spectra of the ionogel membranes obtained in Examples 1 and 9. When the amounts of adipic acid dihydrazide and diacetone acrylamide are increased tenfold, an infrared spectrum at 1665 cm⁻¹ can be observed. -1 The presence of a relatively obvious C=N characteristic peak at the point indicates the formation of an acylhydrazone bond. Detailed Implementation

[0046] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0047] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0048] Example 1

[0049] (1) On a glass substrate (4×4cm) covered with commercial polypropylene tape. 2 0.5 mL of an ethanol dispersion containing ~10% by mass of silica-coated polystyrene microspheres with a particle size of ~210 nm (the silica shell is about 20 nm thick) was coated onto the surface. After the ethanol completely evaporated, the microspheres self-assembled to form an opal photonic crystal template.

[0050] (2) 500 μm thick commercial polyimide tape was adhered to both ends of a hydrophobic substrate with an opal photonic crystal template assembled thereon. A glass slide was then placed over the substrate, and a mixture was poured between the substrate and the glass slide. The mixture consisted of: an aqueous solution of acryloyloxyethyltrimethylammonium chloride (80% by mass), 1-ethyl-3-methylimidazolium tetrafluoroborate, diacetone acrylamide, and photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:200:2:1, and a molar ratio of diacetone acrylamide to adipate dihydrazide in a molar ratio of 2:1. The composite film was obtained by polymerization under 12W ultraviolet light for 1 hour.

[0051] (3) Peel the composite membrane obtained in step (2) off the substrate and flip it so that the microsphere array faces upward on the substrate. Attach 1000μm thick commercial polyimide tape to both ends of the substrate, cover it with a glass plate, pour the mixture used in step (2) between the substrate and the glass plate, use 12W ultraviolet light to polymerize for 1 hour, completely peel it off from the substrate, and dry it in an oven at 60℃ to obtain a highly elastic self-healing mechanical color-changing ionogel membrane with an initial color of red.

[0052] Example 2

[0053] (1) On a glass slide with commercial polypropylene tape attached, a substrate (4×4cm) 2 0.5 mL of an ethanol dispersion containing ~10% by mass of silica-coated polystyrene microspheres with a particle size of ~210 nm (the silica shell is about 20 nm thick) was coated onto the surface. After the ethanol completely evaporated, the microspheres self-assembled to form an opal photonic crystal template.

[0054] (2) 500 μm thick commercial polyimide tape was adhered to both ends of a hydrophobic substrate with an opal photonic crystal template assembled thereon. A glass slide was then placed on top, and a mixture was poured in. The mixture consisted of: 80% (w / w) acryloxyethyltrimethylammonium chloride aqueous solution, 1-butyl-3-methylimidazolium tetrafluoroborate, diacetone acrylamide, and photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:200:2:1, and a molar ratio of diacetone acrylamide to adipate dihydrazide in a ratio of 2:1. The composite film was obtained by polymerization under 12W ultraviolet light for 1 hour.

[0055] (3) Peel the composite membrane obtained in step (2) off the substrate and flip it so that the microsphere array faces upward on the substrate. Attach 1000μm thick commercial polyimide tape to both ends of the substrate, cover it with a glass plate, pour the mixture used in step (2) between the substrate and the glass plate, use 12W ultraviolet light to polymerize for 1 hour, completely peel it off from the substrate, and dry it in an oven at 60℃ to obtain a highly elastic self-healing mechanical color-changing ionogel membrane with an initial color of red.

[0056] Example 3

[0057] (1) On a glass slide with commercial polypropylene tape attached, a substrate (4×4cm) 2 0.5 mL of an ethanol dispersion containing ~10% by mass of silica-coated polystyrene microspheres with a particle size of ~210 nm (the silica shell is about 20 nm thick) was coated onto the surface. After the ethanol completely evaporated, the microspheres self-assembled to form an opal photonic crystal template.

[0058] (2) 500 μm thick commercial polyimide tape was adhered to both ends of a hydrophobic substrate with an opal photonic crystal template assembled thereon. A glass slide was then placed on top, and a mixture was poured in. The mixture consisted of sulfobetaine methacrylate, 1-ethyl-3-methylimidazolium malononitrile, diacetone acrylamide, and photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:200:2:1, and the molar ratio of diacetone acrylamide to adipate dihydrazide was 2:1. The composite film was obtained by polymerization under 12W ultraviolet light for 1 hour.

[0059] (3) Peel the composite membrane obtained in step (2) off the substrate and flip it so that the microsphere array faces upward on the substrate. Attach 1000μm thick commercial polyimide tape to both ends of the substrate, cover it with a glass plate, pour the mixture used in step (2) between the substrate and the glass plate, use 12W ultraviolet light to polymerize for 1 hour, and completely peel it off from the substrate to obtain a highly elastic self-healing mechanical color-changing ionogel membrane with an initial color of red.

[0060] Example 4

[0061] (1) On a glass slide with commercial polypropylene tape attached, a substrate (4×4cm) 2 0.5 mL of an ethanol dispersion containing ~10% by mass of silica-coated polystyrene microspheres (with a silica shell thickness of approximately 20 nm) with a particle size of ~195 nm was coated onto the surface. After the ethanol completely evaporated, the microspheres self-assembled to form an opal photonic crystal template.

[0062] (2) 500 μm thick commercial polyimide tape was adhered to both ends of a hydrophobic substrate with an opal photonic crystal template assembled thereon. A glass slide was then placed on top, and a mixture was poured in. The mixture consisted of: 80% (w / w) acryloxyethyltrimethylammonium chloride aqueous solution, 1-ethyl-3-methylimidazolium tetrafluoroborate, diacetone acrylamide, and photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:200:2:1, and the molar ratio of diacetone acrylamide to adipate dihydrazide was 2:1. The composite film was obtained by polymerization under 12W ultraviolet light for 1 hour.

[0063] (3) Peel the composite membrane obtained in step (2) off the substrate and flip it so that the microsphere array faces upward on the substrate. Attach 1000μm thick commercial polyimide tape to both ends of the substrate, cover it with a glass plate, pour the mixture used in step (2) between the substrate and the glass plate, use 12W ultraviolet light to polymerize for 1 hour, completely peel it off from the substrate, and dry it in an oven at 60℃ to obtain a highly elastic self-healing mechanical color-changing ionogel membrane with an initial color of orange.

[0064] Example 5

[0065] (1) On a glass slide with 5 commercial polypropylene tape attached, a substrate (4×4cm) 2 0.5 mL of an ethanol dispersion containing ~10% by mass of silica-coated polystyrene microspheres (with a silica shell thickness of approximately 15 nm) with a particle size of ~182 nm was coated onto the surface. After the ethanol completely evaporated, the microspheres self-assembled to form an opal photonic crystal template.

[0066] (2) 500 μm thick commercial polyimide tape was adhered to both ends of a hydrophobic substrate with an opal photonic crystal template assembled thereon. A glass slide was then placed on top, and a mixture was poured in. The mixture consisted of: 80% (w / w) acryloxyethyltrimethylammonium chloride aqueous solution, 1-ethyl-3-methylimidazolium tetrafluoroborate, diacetone acrylamide, and photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:200:2:1, and the molar ratio of diacetone acrylamide to adipate dihydrazide was 2:1. The composite film was obtained by polymerization under 12W ultraviolet light for 1 hour.

[0067] (3) Peel the composite membrane obtained in step (2) off the substrate and flip it so that the microsphere array faces upward on the substrate. Attach 1000μm thick commercial polyimide tape to both ends of the substrate, cover it with a glass plate, pour the mixture used in step (2) between the substrate and the glass plate, use 12W ultraviolet light to polymerize for 1 hour, completely peel it off from the substrate, and dry it in an oven at 60℃ to obtain a highly elastic self-healing mechanical color-changing ionogel membrane with an initial color of green.

[0068] Example 6

[0069] (1) On a glass slide with commercial polypropylene tape attached, a substrate (4×4cm) 2 0.5 mL of an ethanol dispersion containing ~10% by mass of silica-coated polystyrene microspheres with a particle size of ~210 nm (the silica shell is about 20 nm thick) was coated onto the surface. After the ethanol completely evaporated, the microspheres self-assembled to form an opal photonic crystal template.

[0070] (2) 500 μm thick commercial polyimide tape was adhered to both ends of a hydrophobic substrate with an opal photonic crystal template assembled thereon. A glass slide was then placed on top, and a mixture was poured in. The mixture consisted of: acryloyloxyethyltrimethylammonium chloride solution (80% by mass), 1-ethyl-3-methylimidazolium tetrafluoroborate, diacetone acrylamide, and photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:200:2:1, and the molar ratio of diacetone acrylamide to succinic acid dihydrazide was 2:1. The composite film was obtained by polymerization under 12W ultraviolet light for 1 hour.

[0071] (3) Peel the composite membrane obtained in step (2) off the substrate and flip it so that the microsphere array faces upward on the substrate. Attach 1000μm thick commercial polyimide tape to both ends of the substrate, cover it with a glass plate, pour the mixture used in step (2) between the substrate and the glass plate, use 12W ultraviolet light to polymerize for 1 hour, completely peel it off from the substrate, and dry it in an oven at 60℃ to obtain a highly elastic self-healing mechanical color-changing ionogel membrane with an initial color of red.

[0072] Example 7

[0073] (1) On a glass slide with commercial polypropylene tape attached, a substrate (4×4cm) 2 0.5 mL of an ethanol dispersion containing ~10% by mass of silica-coated polystyrene microspheres with a particle size of ~210 nm (the silica shell is about 20 nm thick) was coated onto the surface. After the ethanol completely evaporated, the microspheres self-assembled to form an opal photonic crystal template.

[0074] (2) 500 μm thick commercial polyimide tape was adhered to both ends of a hydrophobic substrate with an opal photonic crystal template assembled thereon. A glass slide was then placed on top, and a mixture was poured in. The mixture consisted of: acryloyloxyethyltrimethylammonium chloride solution (80% by mass), 1-ethyl-3-methylimidazolium tetrafluoroborate, diacetone acrylamide, and photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:200:4:1, and the molar ratio of diacetone acrylamide to adipate dihydrazide was 2:1. The composite film was obtained by polymerization under 12W ultraviolet light for 1 hour.

[0075] (3) Peel the composite membrane obtained in step (2) off the substrate and flip it so that the microsphere array faces upward on the substrate. Attach 1000μm thick commercial polyimide tape to both ends of the substrate, cover it with a glass plate, pour the mixture used in step (2) between the substrate and the glass plate, use 12W ultraviolet light to polymerize for 1 hour, completely peel it off from the substrate, and dry it in an oven at 60℃ to obtain a highly elastic self-healing mechanical color-changing ionogel membrane with an initial color of red.

[0076] Example 8

[0077] (1) On a glass slide with commercial polypropylene tape attached, a substrate (4×4cm) 2 0.5 mL of an ethanol dispersion containing ~10% by mass of silica-coated polystyrene microspheres with a particle size of ~210 nm (the silica shell is about 20 nm thick) was coated onto the surface. After the ethanol completely evaporated, the microspheres self-assembled to form an opal photonic crystal template.

[0078] (2) 500 μm thick commercial polyimide tape was adhered to both ends of a hydrophobic substrate with an opal photonic crystal template assembled thereon. A glass slide was then placed on top, and a mixture was poured in. The mixture consisted of: acryloyloxyethyltrimethylammonium chloride solution (80% by mass), 1-ethyl-3-methylimidazolium tetrafluoroborate, diacetone acrylamide, and photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:300:2:1, and the molar ratio of diacetone acrylamide to adipate dihydrazide was 2:1. The composite film was obtained by polymerization under 12W ultraviolet light for 1 hour.

[0079] (3) Peel the composite membrane obtained in step (2) off the substrate and flip it so that the microsphere array faces upward on the substrate. Attach 1000μm thick commercial polyimide tape to both ends of the substrate, cover it with a glass plate, pour the mixture used in step (2) between the substrate and the glass plate, use 12W ultraviolet light to polymerize for 1 hour, completely peel it off from the substrate, and dry it in an oven at 60℃ to obtain a highly elastic self-healing mechanical color-changing ionogel membrane with an initial color of red.

[0080] Example 9

[0081] A 1000 μm thick layer of commercial polyimide tape was adhered to both ends of a substrate on a glass slide covered with commercial polypropylene tape. The glass slide was then covered, and a mixture was poured between the substrate and the glass slide. The mixture consisted of: an aqueous solution of acryloyloxyethyltrimethylammonium chloride (80% by mass), 1-ethyl-3-methylimidazolium tetrafluoroborate, diacetone acrylamide, and the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:200:20:1; and a molar ratio of diacetone acrylamide to adipate dihydrazide in a molar ratio of 2:1. Polymerization was performed using 12 W of UV light for 1 hour to obtain an ionogel membrane for characterizing the relevant structure.

[0082] Example 10

[0083] Commercial polyimide tape with a thickness of 1000 μm was adhered to both ends of a substrate on a glass slide covered with commercial polypropylene tape. The glass slide was then covered, and a mixture was poured between the substrate and the glass slide. The mixture consisted of: an aqueous solution of acryloyloxyethyltrimethylammonium chloride (80% by mass), 1-ethyl-3-methylimidazolium tetrafluoroborate, diacetone acrylamide, and the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:200:2:1. Polymerization was performed using 12 W of ultraviolet light for 1 hour to obtain an ionogel film.

[0084] Example 11

[0085] Commercial polyimide tape with a thickness of 1000 μm was adhered to both ends of a substrate on a glass slide covered with commercial polypropylene tape. The glass slide was then covered, and a mixture was poured between the substrate and the glass slide. The mixture consisted of 80% (w / w) acryloyloxyethyltrimethylammonium chloride aqueous solution, 1-ethyl-3-methylimidazolium tetrafluoroborate, adipate dihydrazide, and the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:200:1:1. Polymerization was performed using 12 W of ultraviolet light for 1 hour to obtain an ionogel film.

[0086] Example 12

[0087] Commercial polyimide tape with a thickness of 1000 μm was adhered to both ends of a substrate on a glass slide covered with commercial polypropylene tape. The glass slide was then covered, and a mixture was poured between the substrate and the glass slide. The mixture consisted of an aqueous solution of acryloyloxyethyltrimethylammonium chloride (80% by mass), 1-ethyl-3-methylimidazolium tetrafluoroborate, and the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 100:200:1. Polymerization was performed using 12W ultraviolet light for 1 hour to obtain an ionogel film.

[0088] For all those skilled in the art, without departing from the scope of the present invention, possible modifications and variations can be made to the solutions of the present invention using the above-described technical content, or equivalent embodiments can be transformed into equivalent changes. Therefore, any simple modifications, equivalent changes, or alterations made to the above embodiments based on the essence of the present invention without departing from the content of the present invention are all within the protection scope of the present invention.

Claims

1. A highly elastic, self-healing, mechanically color-changing ionogel membrane, characterized in that, Non-close-packed ordered microsphere arrays are embedded in a bilayer ionogel membrane obtained by photopolymerization of ionic acrylic acid or acrylate monomers. The ionogel membrane is chemically cross-linked by forming reversible hydrazone bonds through the reaction of diacetone acrylamide and diacylhydrazine compounds, and encapsulates 50%-75% by mass of ionic liquid. The non-densely packed ordered microsphere array is obtained by swelling a densely packed ordered microsphere array. The microspheres are silica microspheres or core-shell structured microspheres with silica as the shell layer. The core-shell structured microspheres are one of the following: silica-coated polystyrene core-shell microspheres, silica-coated titanium dioxide core-shell microspheres, silica-coated cerium dioxide core-shell microspheres, silica-coated zinc sulfide core-shell microspheres, silica-coated polymethyl methacrylate core-shell microspheres, and silica-coated zinc oxide core-shell microspheres. The diameter of the microspheres is 150~220 nm, the shell thickness of the core-shell structured microspheres is 10~25 nm, and the thickness of the microsphere array is 5~10 μm. The ionic acrylic or acrylate monomer is one or more of acryloyloxyethyltrimethylammonium chloride and methacryloyloxyethyltrimethylammonium chloride. The ionic liquid is one or more of tetrafluoroborate, hexafluorophosphate, onium malononitrile salt, and bis(trifluoromethanesulfonyl)imide salt; The preparation method of the highly elastic self-healing mechanical color-changing ionogel membrane includes the following steps: ① A microsphere dispersion with a mass fraction of 5-10% is coated on a hydrophobic substrate. After the solvent has completely evaporated, the microspheres self-assemble to form an opal photonic crystal template. ② Adhere polyimide tape to both ends of a hydrophobic substrate with an opal photonic crystal template assembled on it, cover it with a transparent substrate, and pour a mixture of ionic acrylic or acrylate monomers, diacetone acrylamide, diacylhydrazine compounds, ionic liquids and photoinitiators between the two substrates. Use 10~20W of ultraviolet light to polymerize for 1~2 hours to obtain a composite film. ③ Peel off the composite membrane obtained in step ②, place the microsphere array side up on the substrate, attach polyimide tape to both ends of the substrate, cover with a transparent substrate, pour the mixture used in step ② between the two substrates, use 10~20W power ultraviolet light to polymerize for 1~2 hours, and after completely peeling off from the substrate, a highly elastic self-healing mechanical color-changing ionogel membrane is obtained. In step ②, the dihydrazide compound is one of succinic dihydrazide, adipate dihydrazide, oxaloyl dihydrazide, maleic dihydrazide, and 3,3'-dithiobis(propionyl hydrazide); the photoinitiator is one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin dimethyl ether, and 1-hydroxycyclohexylphenylacetone.

2. The highly elastic self-healing mechanical color-changing ionogel membrane according to claim 1, characterized in that, The densely packed ordered microsphere array is obtained through convective self-assembly.

3. The highly elastic self-healing mechanical color-changing ionogel membrane according to claim 1, characterized in that, In step ①, the hydrophobic substrate is one of polymethyl methacrylate sheet, polytetrafluoroethylene sheet, or a flat sheet with polypropylene tape attached; the coating amount of the microsphere dispersion is 100-200 microliters per square centimeter; the microsphere dispersion is prepared with ethanol.

4. The highly elastic self-healing, mechanically color-changing ionogel membrane according to claim 1, characterized in that, In step ②, the thickness of the polyimide tape is 200~1000 μm; the transparent substrate is one of polymethyl methacrylate sheet, glass sheet, or a planar transparent sheet with polypropylene tape.

5. The highly elastic self-healing mechanical color-changing ionogel membrane according to claim 1, characterized in that, The mass ratio of the ionic acrylic acid or acrylate monomer to diacetone acrylamide is 100:1 to 100:4, the molar ratio of diacetone acrylamide to diacylhydrazine compound is 2:1 to 5:1, the mass ratio of the ionic acrylic acid or acrylate monomer to ionic liquid is 1:1 to 1:3, and the mass ratio of the ionic acrylic acid or acrylate monomer to photoinitiator is 100:0.5 to 100:

2. When the ionic acrylic acid or acrylate monomer is in solution form, the solvent needs to be dried by heating after complete peeling from the substrate in step ③.

6. The application of the highly elastic self-healing mechanochromic ionogel membrane according to any one of claims 1-2 in the fields of mechanical sensing, motion detection, flexible display or interactive devices.

Images