Self-healing metal-ligand polymer materials

Abstract

In various aspects, a self-healing polymer material and a method for manufacturing the self-healing material are provided. The self-healing material may comprise a polymer network defining one or more ligands having metal ion coordination sites. The polymer network may be a poly(vinyl alcohol) (PVA) hydrogel, and the metal ion may be a transition metal, such as zinc. The metal ion is distributed within the polymer network and is capable of interacting with at least one metal ion coordination site via reversible coordination bonds. The polymer network is capable of self-healing mechanical cracks or cuts under ambient conditions for less than or equal to about 30 minutes, and in some variations for only 5–10 seconds. This self-healing polymer material can be used to form pressure-sensitive adhesives.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 910,972, filed October 4, 2019. The entire disclosure of the above application is incorporated herein by reference. Technical Field

[0003] This disclosure relates to self-healing polymer materials having metal-ligand complexes that are capable of self-healing under environmental conditions. Background Technology

[0004] This section provides background information relating to this disclosure, which is not necessarily prior art.

[0005] Self-healing is generally understood as the ability of a material to recover itself upon injury (e.g., mechanical damage). Self-healing materials can improve the lifespan, recyclability, durability, energy efficiency, and safety of synthetic materials. For example, autonomous self-healing materials are capable of repairing themselves upon mechanical damage or chemical corrosion. Some self-healing materials react in situ to heal. Synthetic materials with self-healing properties are well-suited for a variety of applications, including self-healing adhesives, self-healing sensors, and self-healing coatings, applicable to a wide range of applications, including electronic and medical devices. Various self-healing strategies for polymer systems have been investigated. For example, in some techniques, reagents or catalysts for self-healing materials can be distributed within the polymer matrix, ready to react when localized damage occurs. Traditionally, self-healing polymers employ hydrogen bonds, dynamic covalent bonds, ion-dipole interactions, disulfide bonds, liquid metal interactions, and even the incorporation of healing agents as healing motifs. Autonomous self-healing materials exhibiting repeatable self-healing capabilities under environmental conditions and extended environmental stability are highly desirable. Summary of the Invention

[0006] This section provides a general overview of the disclosure, but is not a full disclosure of the entire scope or all features of the disclosure.

[0007] In some aspects, this disclosure relates to a self-healing polymer material comprising a polymer network containing poly(vinyl alcohol) (PVA) defining one or more ligands having transition metal ion coordination sites. The self-healing polymer material has transition metal ions distributed throughout the polymer network. The transition metal ions are capable of interacting with the transition metal ion coordination sites via reversible coordination bonds. Therefore, the polymer network is capable of self-healing mechanical cracks or cuts under ambient conditions within approximately 30 minutes.

[0008] On the one hand, the transition metal ion is zinc ion (Zn). 2+ ).

[0009] On the one hand, polymer networks can self-heal mechanical cracks or cuts within approximately one minute under environmental conditions.

[0010] On the one hand, the polymer network also includes additives selected from the group consisting of plasticizers, crosslinking agents, nanoparticles, and combinations thereof.

[0011] On the one hand, the polymer network is a hydrogel.

[0012] On the one hand, PVA molar (N PVA ) and the molar ratio of zinc ions (N) Zn The ratio of ( ) is greater than or equal to about 20:1 to less than or equal to about 10:5.

[0013] On the one hand, the self-healing polymer material also comprises: water, a first complex of a transition metal ion and a coordination site of the transition metal ion, and a second complex of the transition metal ion and water. The ratio of the first complex to the second complex can be greater than or equal to about 1:1 and less than or equal to about 5:1.

[0014] On the one hand, self-healing polymer materials can exhibit elongation under strain greater than or equal to approximately 100% after the self-healing of mechanical cracks or cuts.

[0015] On the one hand, self-healing polymer materials have a transmittance of more than or equal to about 70% for electromagnetic radiation wavelengths from about 380 nm to less than or equal to about 780 nm.

[0016] On the one hand, self-healing polymer materials have a sheet resistance of less than or equal to about 10 MΩ / square.

[0017] On one hand, a self-healing pressure-sensitive adhesive is provided, formed from the self-healing polymer material described above. This self-healing pressure-sensitive adhesive is capable of bonding to at least one substrate selected from the group consisting of glass, plastics, metals, fabrics, and biological tissues.

[0018] On the other hand, the bonding strength of the self-healing pressure-sensitive adhesive to at least one substrate is greater than or equal to about 0.05 MPa without any preload, and 0.15 MPa at a preload level of 1.5 MPa.

[0019] On the other hand, self-healing pressure-sensitive adhesives are water-resistant and solvent-resistant.

[0020] On the other hand, self-healing pressure-sensitive adhesives have a maximum shear strength greater than or equal to about 100 kPa.

[0021] On one hand, a device comprising the self-healing polymer material as described above is provided. This device can be selected from the group consisting of: electronic devices, displays, wearable devices, vehicles, robotic arms, manufacturing equipment, construction equipment, medical devices, packaging, toys, sensors, and energy conversion or storage devices.

[0022] In some other aspects, this disclosure relates to a self-healing polymer material comprising: a polymer network including one or more ligands having transition metal ion coordination sites; and transition metal ions distributed in the polymer network and capable of interacting with the transition metal ion coordination sites via coordination bonds. The self-healing material satisfies the following condition:

[0023] E a = a·f+b; and Among them, E a denoted as activation energy, f as the molar ratio of transition metal ions to ligands, a as the slope of the activation energy versus molar ratio, where a ranges from approximately 1 to approximately 5, and b as the y-intercept of the activation energy versus the metal-ligand molar ratio. The polymer network is capable of self-healing mechanical cracks or cuts under ambient conditions within approximately 30 minutes.

[0024] On the one hand, self-healing polymer materials have a Young's modulus expressed as: E = A·exp(-Bf), And A > 1, where E is Young's modulus and f is the ratio of the molar amount of transition metal ions to the molar amount of ligands in the polymer network.

[0025] On the one hand, self-healing polymer materials have a Young's modulus (E) greater than or equal to about 0.01 kPa to less than or equal to 100 kPa.

[0026] On the one hand, the self-healing polymer material is cross-linked and has a Young's modulus greater than or equal to about 1 kPa to less than or equal to 100 MPa.

[0027] On the one hand, the self-healing pressure-sensitive adhesive formed from the above-mentioned self-healing polymer material can have a total adhesive strength (σ) of the self-healing pressure-sensitive adhesive, expressed as follows. A ):

[0028] in, This refers to the normal adhesive strength of a self-healing pressure-sensitive adhesive without any preload. Let P be the saturation value of the normal adhesive strength of the self-healing pressure-sensitive adhesive under preload, P be the preload applied to the self-healing pressure-sensitive adhesive, and τ be the relaxation value adhesive strength under preload, where τ is greater than or equal to about 0.1 and less than or equal to about 1.

[0029] On the one hand, a self-healing pressure-sensitive adhesive can have a ratio of τ after self-healing to the initial τ before any damage, expressed as follows: Where, τ 初始 τ represents the relaxation strength before damage. 自愈合 The relaxation strength after self-healing.

[0030] On the one hand, self-healing pressure-sensitive adhesives can have a total adhesive strength (σ) greater than or equal to about 0.1 MPa to less than or equal to about 5 MPa. A ).

[0031] On the other hand, self-healing pressure-sensitive adhesives possess ionomer properties as represented by the following: Where R -1 The reciprocal of the measured resistance. The maximum value of the reciprocal of the resistance of the self-healing adhesive, f is the ratio of the molar amount of transition metal ions to the molar amount of ligands in the polymer network, f C is the percolation threshold, which is greater than 0 and less than or equal to about 0.1, and r is a critical exponent greater than or equal to about 1 and less than or equal to about 2.

[0032] In other aspects, this disclosure relates to a method for manufacturing a self-healing polymer material. The method may include mixing a polymer precursor and a precursor containing a transition metal to form a mixture of a polymer and transition metal ions distributed in the polymer, the polymer having one or more ligands having at least one coordination site for a transition metal ion. Next, the method includes freezing the mixture and then thawing it. This forms a self-healing material comprising a polymer network having transition metal ions distributed therein. At least one transition metal ion coordination site on one or more ligands of the polymer network reacts with the transition metal to form a reversible coordination bond. The self-healing material is capable of self-healing mechanical cracks or cuts under ambient conditions in the absence of external stimulation within approximately 30 minutes.

[0033] On the one hand, at least three cycles of freezing and thawing are performed.

[0034] On one hand, the method also includes a water removal process on the self-healing material after thawing. The activation energy of the self-healing material is controlled by the amount of water removed during the water removal process.

[0035] On the one hand, the method also includes subjecting the self-healing material to a temperature greater than or equal to about 30°C to less than or equal to about 60°C after thawing.

[0036] Other applicable fields will become apparent from the description provided herein. The descriptions and specific embodiments in this overview are intended for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0037] The accompanying drawings described herein are for illustrative purposes only, representing selected embodiments rather than all possible implementations, and are not intended to limit the scope of this disclosure.

[0038] Figure 1 Visual observations show the characteristics of the self-healing polymer as the corresponding amounts of transition metal ions (zinc in this paper) and poly(vinyl alcohol) (PVA) ligands change. More specifically, a self-healing hydrogel based on a Zn-PVA complex subjected to more than three freeze-thaw cycles is shown.

[0039] Figures 2A-2B Two types of complexes present in a self-healing polymer material prepared according to this disclosure are shown. Figure 2A Zinc-poly(vinyl alcohol) (PVA) ligand complexes that contribute to self-healing bonds in polymer materials are shown. On the other hand, Figure 2B It appears to be a zinc-water complex that inhibits self-healing.

[0040] Figure 3 The mechanism of forming Zn-PVA complexes in self-healing materials prepared according to certain aspects of this disclosure after undergoing a freeze-thaw process is shown.

[0041] Figure 4 Evaluations of the self-healing time of certain PVA-Zn hydrogel self-healing polymers prepared according to certain aspects of this disclosure are shown: one example (indicated by a black circle) manufactured by a freeze-thaw process and self-healing at 22°C, and another example (indicated by a red circle) manufactured by a freeze-thaw process and additionally heated at 30°C.

[0042] Figure 5 The effect of temperature on the self-healing time of a self-healing polymer prepared according to certain aspects of this disclosure is shown. The self-healing polymer is based on coordination bonds formed by a freeze-thaw process followed by additional heating at 30°C, 40°C, 50°C or 60°C.

[0043] Figure 6 The comparative self-healing times of polymers prepared according to certain variations of this disclosure are shown. Black circles indicate self-healing polymer samples containing poly(vinyl alcohol) (PVA) and zinc (Zn) formed by three cycles of freeze-thaw processes. Red circles indicate PVA / Zn self-healing polymer samples that underwent three cycles of freeze-thaw processes followed by heating at 60°C. Blue circles indicate PVA / Zn self-healing polymer samples formed by the same freeze-thaw process followed by a 72-hour dehumidification process in a desiccator set to 22°C and 17% RH.

[0044] Figure 7 The self-healing time of a self-healing PVA and Zn polymer according to certain aspects of this disclosure is shown. The polymer is manufactured by a three-cycle freeze-thaw process followed by a 72-hour dehumidification process in a dryer set at 22°C and 17% RH.

[0045] Figure 8 An Arrhenius plot of ln(k) versus 1000 / T is shown to illustrate the self-healing rate constant, which is inversely proportional to the absolute temperature of the self-healing polymer produced by a three-cycle freeze-thaw process without dehumidification.

[0046] Figure 9An Arrhenius plot of ln(k) versus 1000 / T is shown to illustrate the self-healing rate constant, which is inversely proportional to the absolute temperature of the self-healing polymer manufactured by passing through a 3-cycle freeze-thaw process followed by a 72-hour dehumidification process in a dryer set at 22°C and 17% relative humidity (RH).

[0047] Figure 10 The activation energy (E) of the self-healing polymer manufactured according to certain aspects of this disclosure via a three-cycle freeze-thaw process is shown. a (Black circle), and the activation energy (E) of the self-healing polymer manufactured through the same process, followed by a 72-hour dehumidification process in a dryer set at 22°C and 17% RH. a (Red circle).

[0048] Figure 11 Stress-strain curves of a self-healing polymer based on the coordination bonds of Zn-PVA after three cycles of freeze-thaw process without dehumidification are shown. (The inset shows a magnified view of the same results on the y-axis.)

[0049] Figure 12 Stress-strain curves of a self-healing polymer based on the coordination bonds of Zn-PVA after three cycles of freeze-thaw and then dehumidification are shown.

[0050] Figure 13 The Young's modulus (E) of a self-healing polymer based on a Zn-PVA complex prepared according to certain aspects of this disclosure after undergoing three cycles of freeze-thaw process is shown. The blue and red circles represent the modulus of the polymer before and after 72 hours of dehumidification in a desiccator (22°C and 17% RH), respectively, with the addition of zinc ions (Zn... 2+ The modulus of a self-healing polymer is measured by the change in molar fraction between PVA and PVA. Figure 9 The equations inserted in the table fit all the data using blue and red dashed lines. The yellow boxes show the modulus range of human skin surveyed from the references.

[0051] Figure 14 Showing relative to Zn 2+The elongation and tensile strength were measured based on the mole fraction of PVA, which demonstrate the brittle-ductile transition of the self-healing polymer prepared according to certain aspects of this disclosure. All samples based on the Zn-PVA complex were prepared by a three-cycle freeze-thaw process followed by dehumidification at 22°C and 17% RH for 72 hours. Red indicates tensile strength at fracture, while black indicates elongation at fracture.

[0052] Figure 15 A series of photographs show self-healing polymer materials of PVA and Zn being cut under ambient conditions, reattached by applying slight pressure (with a self-healing time of less than 10 seconds), and then stretched (with the healed polymer remaining intact).

[0053] Figure 16 This is a photograph of a self-healing polymer system containing PVA and Zn, which exhibits ultra-high elongation (approximately 4000%) at a low strain rate of 10 mm / min.

[0054] Figure 17 Photographs are shown of a self-healing polymer system prepared according to certain aspects of this disclosure, exhibiting anti-scratching test results at 0 seconds and after 5 seconds, 15 seconds, 30 seconds, and 1 minute. The self-healing polymer, with a thickness of 300 μm, is laminated onto a 1.1 mm thick glass substrate. The self-healing polymer is formed by undergoing a freeze-thaw cycle of 3 times, followed by a dehumidification process for 72 hours in a desiccator set to 22°C and 17% RH. Scratches were created by manually scratching the 300 μm thick film with a razor blade. Without any intervention or irritation, the damage initiated self-healing, and the scratches almost disappeared within 5 minutes at room temperature.

[0055] Figure 18 The normal adhesive stress of self-healing adhesives (SHAs) prepared according to certain aspects of this disclosure, laminated onto a 1.1 mm thick glass substrate with preload, was measured to evaluate the performance of pressure-sensitive adhesives (PSAs). All samples were manufactured through a 3-cycle freeze-thaw process followed by a 72-hour dehumidification process in a desiccator set to 22°C and 17% RH. Commercially available products (3M Scotch) were provided. A comparison of the results of Tape 810 with those of bio-inspired Gecko-patterned physical adhesive.

[0056] Figure 19 Photographs show observations of the adhesive properties of a self-healing adhesive (SHA) prepared according to certain aspects of this disclosure, based on a Zn-PVA complex subjected to a three-cycle freeze-thaw process followed by a 72-hour dehumidification process in a dryer set at 22°C and 17% RH. The adhesive properties of the SHA were evaluated for bonding to a variety of different substrates, including glass, metal, and plastic.

[0057] Figures 20A-20B The effect of coordination bonding on the adhesion between a self-healing adhesive (SHA) prepared according to certain aspects of this disclosure and a glass substrate is shown. Based on... Figure 20A The information shown in the literature (from M. Tupy et al., Effect of water and acid-base reactants on adhesive properties of various plasticized poly(vinyl butyral) sheet, J. Appl. Polym. Sci. 127, 3474 (2013)) is in Figure 20B A hypothetical schematic structure of SHA prepared according to this disclosure was generated. Since coordinate bonds are formed, and these coordinate bonds play a major role in enhancing the adhesive properties of SHA, SHA is considered to exhibit excellent adhesive strength on glass.

[0058] Figures 21A-21B The self-healing properties of a pressure-sensitive adhesive (PSA) prepared according to certain aspects of this disclosure are demonstrated. Figure 21A A schematic diagram of the self-healing process of PSA after it is bonded to a glass substrate is shown. Figure 21B The comparison shows the change in adhesive strength of PSA samples with preload before and after self-healing.

[0059] Figure 22 Stress-strain curves are shown, demonstrating the self-healing behavior of a self-healing adhesive (SHA) prepared according to certain aspects of this disclosure. The SHA contains PVA and Zn. 2+ The molar ratio is 10:3, and it is manufactured through a 3-cycle freeze-thaw process followed by a 72-hour dehumidification process in a dryer set at 22°C and 17% RH.

[0060] Figures 23A-23CThe chemical stability of the self-healing adhesive (SHA) prepared according to certain aspects of this disclosure in deionized water, isopropanol (IPA), acetone, dimethylformamide (DMF), and benzene was demonstrated when glass bottles and slides were sealed for 15 days under ambient conditions. Figure 23A The adhesion was shown in the presence of DMF. Figure 23B The images are of samples filled with the various solvents listed above. Figure 23C This is a photo of the same sample taken 15 days later.

[0061] Figure 24 The transmittance level and haze level of the self-healing adhesive (SHA) prepared according to certain aspects of this disclosure are shown.

[0062] Figure 25 The conductivity (resistivity) properties of the self-healing adhesive (SHA) as an ionomer based on metal-ligand coordination bonds and the percolation model shown in the illustration are displayed. The red line agrees well with the measured data (black circle).

[0063] Figure 26 The extinction at 550 nm wavelength is shown for self-healing polymers prepared according to certain aspects of this disclosure, which vary with the molar ratio of zinc ions to PVA ligands.

[0064] Figures 27A-27C The measurements of shear strength of self-healing polymers prepared according to certain aspects of this disclosure are shown based on ASTM D1002. Figure 27A A comparison of the time-varying shear strength of double-sided tape, commercially available pressure-sensitive adhesive, and self-healing polymer prepared according to certain aspects of this disclosure is shown. Figure 27B A schematic diagram of the setup used for shear strength testing is shown. Figure 27C Two photographs show the testing equipment used for shear strength testing.

[0065] Throughout the various views of the accompanying drawings, corresponding reference numerals denote the respective components. Detailed Implementation

[0066] The provision of embodiments makes this disclosure complete and will fully communicate the scope to those skilled in the art. Numerous specific details, such as specific components, parts, apparatuses, and methods, are set forth to provide a complete understanding of embodiments of this disclosure. It will be apparent to those skilled in the art that specific details are not required, that embodiments may be embodied in many different forms, and none of these should be construed as limiting the scope of this disclosure. In some embodiments, well-known processes, well-known equipment structures, and well-known technologies are not described in detail.

[0067] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may also be intended to include the plural forms unless the context clearly indicates otherwise. The terms “comprising,” “including,” “containing,” and “having” are open-ended and therefore specifically refer to the presence of the stated features, elements, components, steps, integers, operations, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Although the open-ended term “comprising” should be understood as a non-limiting term used to describe and claim the various embodiments set forth herein, in some respects the term may alternatively be understood as a more restrictive and binding term, such as “consisting of” or “substantially consisting of.” Thus, for any given embodiment listing components, materials, components, elements, features, integers, operations, and / or process steps, this disclosure also specifically includes embodiments consisting of or substantially consisting of these listed components, materials, components, elements, features, integers, operations, and / or process steps. In the case of “consisting of…”, the alternative embodiment excludes any additional components, materials, elements, features, integers, operations and / or process steps. In the case of “consisting substantially of…”, any additional components, materials, elements, features, integers, operations and / or process steps that substantially affect the essential and novel properties are excluded from the embodiment. However, any components, materials, elements, features, integers, operations and / or process steps that do not substantially affect the essential and novel properties may be included in the embodiment.

[0068] Unless specifically identified as an execution order, the methods, procedures, and operations described herein should not be construed as necessarily requiring them to be performed in the particular order discussed or illustrated. It should also be understood that additional or alternative steps may be taken unless otherwise indicated.

[0069] When a component, element, or layer is referred to as “above another element or layer,” “joined to,” “connected to,” or “coupled to” another element or layer, that component, element, or layer may be directly above, joined to, connected to, or coupled to another component, element, or layer, or there may be intermediate elements or layers. Conversely, when an element is referred to as “directly above another element or layer,” “directly joined to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intermediate elements or layers. Other words used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” vs. “directly between,” “adjacent” vs. “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0070] Although the terms first, second, third, etc., may be used herein to describe various steps, elements, components, regions, layers, and / or segments, these steps, elements, components, regions, layers, and / or segments should not be limited by these terms unless otherwise indicated. These terms may be used only to distinguish one step, element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as “first,” “second,” and other numerical terms used herein do not imply order or sequence. Therefore, the first step, element, component, region, layer, or segment discussed below may be referred to as the second step, element, component, region, layer, or segment without departing from the teachings of the embodiments.

[0071] Spatial or temporal relative terms, such as “before,” “after,” “inside,” “outside,” “below,” “below,” “above,” “over,” etc., may be used herein for the convenience of describing the relationship between one element or feature and another element or feature shown in the figures. In addition to the orientations depicted in the figures, spatial or temporal relative terms may be intended to cover different orientations of the apparatus or system in use or operation.

[0072] Throughout this disclosure, numerical values ​​represent approximate measurements or limitations of a range to cover embodiments with small deviations from a given value and having approximately the value, as well as embodiments with precise stated values. Except for the working examples provided at the end of the detailed description, all numerical values ​​(e.g., numerical values ​​of quantities or conditions) of parameters in this specification (including the claims) should be understood to be modified in all cases by the term “about,” regardless of whether “about” actually appears before the numerical value. “About” indicates that the numerical value allows for some slight imprecision (accuracy of approximating the value by some method; approximating or reasonably approximating the value; almost). If the imprecision provided by “about” is not understood in this common sense in the art, then “about” as used herein at least indicates the variation that may arise from common methods of measuring and using these parameters. For example, “about” may include variations of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in some respects, optionally less than or equal to 0.1%.

[0073] Furthermore, the disclosure of a range includes the disclosure of all values ​​as well as further subdivisions of the range throughout the entire range, including the endpoints and subranges given by the range.

[0074] The embodiments will now be described more fully with reference to the accompanying drawings.

[0075] Self-healing materials are able to repair defects, such as mechanical defects, after damage. For example, defects can be considered as microscopic physical defects (e.g., cuts or cracks with a size of less than or equal to about 1,000 μm) or macroscopic defects (e.g., cuts or cracks with a size of greater than or equal to about 1,000 μm (1 mm)).

[0076] One class of self-healing materials comprises metal-ligand complexes capable of effective self-healing because the coordination bonds between the metal and ligands are reversible under ambient conditions. The metal-ligand interactions are reversible and reproducible. Furthermore, metal-ligand interactions tend to exhibit stronger bond strength to certain substrates compared to hydrogen bonds, which could be advantageous for practical applications. Several self-healing polymers have been reported using reversible metal-ligand interactions. However, some of these metal-ligand-based self-healing materials do not self-heal under ambient conditions and require the application of external energy (such as light or heat) to induce self-healing. Additionally, some metal-ligand-based self-healing materials require complex and difficult-to-process reactions to form the material. For example, spontaneous self-healing materials based on metal-ligand coordination bonds in a pervasive network containing zinc-imidazolium have been studied, as described in D. Mozhdehi et al., “Self-Healing multiphase polymers via dynamic metal-ligand Interactions,” J. Am. Chem. Soc. 136, 16128, (2014). Although metal-ligand complexes can intrinsically possess low glass transition temperatures (T0),… g To achieve self-healing, structural polymers (such as imidazole-containing brush polymers) are formed in the soft matrix region of the matrix, but this requires complex polymerization steps.

[0077] Stretchable self-healing crosslinked polymers via metal-ligand coordination were also investigated, as described in Y. Rao et al., “Stretchable self-healing polymeric dielectrics cross-linked through metal-ligand coordination,” J. Am. Chem. Soc. 138, 6020, (2016). Polydimethylsiloxane (PDMS) with bipyridine as a ligand was further studied by adding metal salts (such as Fe) 2+ and Zn 2+This leads to the formation of metal-ligand complexes, which can induce self-healing and stretchable self-healing materials. However, this requires organic solvents containing toluene, which are generally avoided for environmentally friendly and biocompatible biomaterials (e.g., for electronic products that come into contact with the skin).

[0078] Other self-healing metal-ligand polymer systems are described in U.S. Publication No. 2017 / 0174842 by Wang et al. However, while these materials can undergo autonomous self-healing, they do so at a very slow rate. For example, self-healing is said to occur only after approximately 2 days (48 hours) under ambient conditions.

[0079] In various aspects, this disclosure provides a self-healing polymer material that provides ultra-fast self-healing capability. For example, the self-healing polymer material provided by certain aspects of this disclosure is capable of self-healing mechanical cracks in less than or equal to about 30 minutes under applied pressure and environmental conditions.

[0080] In some variations, which will be further described below, the polymer network comprises poly(vinyl alcohol) (PVA). The PVA polymer may be crosslinked or a hydrogel. The PVA comprises one or more ligands having transition metal ion coordination sites capable of forming coordination bonds with transition metal ions. The coordination bonds formed between the ligands and the metal ions may be reversible. In some aspects, the multiple ligands of the PVA polymer may have metal ion coordination sites capable of forming coordination bonds with transition metal ions. The polymer network may also contain additives known to those skilled in the art. As a non-limiting example, such additives may be selected from the group consisting of plasticizers, crosslinking agents, nanoparticle inclusions, and combinations thereof.

[0081] The transition metal ion can be a metal selected from Groups 4-12 of the IUPAC periodic table, optionally a transition metal from Row 4 of the IUPAC periodic table, such as zinc (Zn), iron (Fe), and / or copper (Cu). In some other respects, the metal can be gold (Au). In some variations, the transition metal is zinc (Zn), and the transition metal ion is a zinc ion (e.g., Zn(2,3-2)-3-3). 2+ Zinc has a rapid ligand exchange rate and participates in reversible metal-ligand interactions, making it particularly suitable as a transition metal ion in the self-healing materials presented herein.

[0082] In some respects, self-healing polymer materials comprise a polymer network having transition metal ions distributed therein. The polymer network may define one or more ligands having coordination sites for the transition metal ions. Thus, the transition metal ions are distributed within the polymer network and are capable of interacting with at least one transition metal ion coordination site via reversible coordination bonds. It should be noted that a single transition metal ion can interact with multiple different transition metal ion coordination sites among multiple ligands in the polymer network. Metal-ligand interactions can be rapidly repeated. For example, the activation and deactivation of metal-ligand bonds can be tuned by the kinetic parameters of the metal-ligand complex. As will be further discussed herein, this method based on metal-ligand complex kinetics enables the formation of ultrafast self-healing materials with highly tunable mechanical properties.

[0083] Self-healing polymer materials are provided in various aspects. In some variations, the self-healing polymer material comprises a polymer network that can be cross-linked and capable of forming strong, reversible coordination bonds with metal ions. The polymer network may comprise poly(vinyl alcohol) (PVA). PVA is a water-soluble polymer with many excellent properties, such as film-forming properties and high bond strength, as well as antistatic properties and biocompatibility and biodegradability. PVA can be used as a raw material for a variety of applications, including coatings, adhesives, surfactants, emulsifiers, dispersants, and films. The polymer network can be further cross-linked by exposure to photochemical radiation (e.g., UV radiation), electron beams, or thermal cross-linking to improve the mechanical properties of the formed material, such as increasing the Young's modulus of the self-healing polymer.

[0084] In one variant, a polymer network comprising poly(vinyl alcohol) (PVA) defines one or more ligands having transition metal ion coordination sites. Furthermore, transition metal ions (such as zinc (Zn) ions) are distributed within the polymer network and are capable of interacting with at least one transition metal ion coordination site via coordinate bonds. These coordinate bonds can be reversible. Zinc-poly(vinyl alcohol) (Zn-PVA) exhibits highly dynamic metal-ligand interactions, providing a robust spontaneous self-healing mechanism. Zinc ions can readily transfer between ligands within the PVA polymer via association and dissociation mechanisms. This active transfer capability of zinc ions enables the formation of active coordinate bonds under optimized conditions. Furthermore, zinc ions can promote the formation of a polymer network comprising polymer chains crosslinked with the hydroxyl groups of PVA via coordinate bonds. This polymer network based on metal-polymer ligand interactions significantly improves the elongation properties of the self-healing material.

[0085] If a self-healing material is subjected to damage in the form of mechanical defects (such as cracks or cuts), the self-healing polymer material can heal itself under low-level pressure and ambient temperature and pressure conditions without the application of any external energy, stimulation, or the use of chemical agents to promote self-healing and damage repair. Under pressure and ambient conditions, the polymer network is able to self-heal mechanical damage (such as cracks or cuts) in less than or equal to about 30 minutes through transition metal-ligand interactions.

[0086] In various respects, this disclosure provides self-healing polymeric materials that may contain Zn-PVA complexes to overcome the low self-healing efficiency of conventional hydrogen-bonded PVA hydrogels. H. Zhang et al., “Poly(vinylalcohol)hydrogel can autonomously self-heal,” ACS Macro Lett. 1, 1233 (2012), describe self-healing PVA hydrogels (containing only PVA) with self-healing properties based on PVA hydrogen bonds. However, the self-healing of these PVA hydrogels depends solely on hydrogen bonding, thus requiring high concentrations of the raw material (more than 35 wt.% PVA) to induce self-healing, and exhibiting long self-healing times, at least several hours to several days. In contrast, as described above, the self-healing polymeric materials provided by this disclosure are capable of self-healing cracks or cuts within less than or equal to about 30 minutes under ambient conditions and upon application of pressure, through transition metal-ligand interactions. In some aspects, the self-healing mechanism provided by the materials of this invention is ultrafast self-healing through metal-ligand interactions controlled by an activation energy. In various respects, self-healing time can be characterized as the time it takes for a material with mechanical damage (such as cracks, fissures, or cuts) to be reattached and bonded together, thereby reaching the level to which the material is considered self-healing.

[0087] For example, a self-healing material can be stretched to have an elongation at least about 100% under strain without any cracks in the healing zone (e.g., after two separate parts are glued together), and this elongation at strain is measured as follows: Among them, L F For the final length, L ○ Let L be the initial length. Therefore, if the initial length L... ○ It is 1mm, and the final length L F If the value is 2, then (2-1) / 1×100=100%, which doubles the length without breakage or damage. In some variations, the self-healing material can be stretched to strain with an elongation of at least about 200%, optionally greater than or equal to 500%, and in some variations optionally greater than or equal to about 1,000% after the self-healing of a mechanical crack or notch.

[0088] In some respects, the self-healing time may be less than or equal to about 10 minutes, optionally less than or equal to about 5 minutes, optionally less than or equal to about 1 minute, optionally less than or equal to about 30 seconds, optionally less than or equal to about 15 seconds, and in some variations, optionally less than or equal to about 10 seconds.

[0089] Embodiments of this disclosure demonstrate ultrafast self-healing polymers and autonomous self-healing polymers based on coordination bonds associated with Zn-PVA complexes. The self-healing polymer materials may comprise a cross-linked polymer network containing Zn-PVA complexes, wherein ligands in the PVA network have transition metal coordination sites, thereby providing the ability to interact with at least one transition metal ion coordination site via reversible coordination bonds. These ligand-transition metal (Zn) complexes are dominant, while transition metal-water complexes are less common. As discussed further below, the presence of a large amount of Zn-H₂O complexes may slow down self-healing, and therefore the activation energy level and self-healing rate can be controlled, for example, by a dehumidification process. While a significant advantage of coordination bonds is their lower sensitivity to moisture compared to hydrogen bonds (which lack stability to moisture), coordination bonds are still affected by moisture. The presence of water leads to a decrease in self-healing efficiency. In some respects, the self-healing polymer comprises water, a first complex formed by a transition metal ion and at least one transition metal ion coordination site on a ligand (e.g., Zn-PVA), and a second complex formed by a transition metal ion and water (e.g., Zn-H2O), wherein the ratio of the first complex to the second complex is greater than or equal to about 1:1 and less than or equal to about 5:1. This is based on the assumption that the Zn ion has a coordination number of 4, and the Zn-PVA complex, i.e., [Zn 2+ (CH2CHO - )4] 2- The molar ratio is 10:2.5. In other words, one mole of zinc ions can form a complex with four moles of hydroxyl groups in PVA. Since the self-healing polymer may have a molar ratio of 10:3 in some variants, the ratio between Zn-PVA and Zn-H2O can be 5:1. This presupposes that zinc ions first participate in the formation of the Zn-PVA complex, and then the remaining zinc ions form the Zn-H2O complex. However, in cases where zinc ions simultaneously form both types of complexes, the ratio between the two complexes may decrease to approximately 1:1 to approximately 4:1.

[0090] Therefore, certain embodiments described herein provide a novel approach to realize ultrafast self-healing polymers and spontaneous self-healing polymers induced by metal-ligand interactions, which further provide activation energy control.

[0091] Figure 1The characteristics of the self-healing polymer are visually observed by comparing the relative amounts of transition metal ions (zinc in this paper) and poly(vinyl alcohol) (PVA) ligands after three cycles of freeze-thaw. This ratio is expressed in PVA molars (N... PVA ) and zinc ions (Zn 2+ (N) Zn The molar ratio of ) is in the range of 10:0 to 10:3. The original (pristine) PVA hydrogel (N) without zinc ions... PVA :N Zn A ratio of 10:0 indicates optical opacity. For example... Figure 1 As shown, Zn-PVA complexed hydrogel (N PVA :N Zn The ratio is 10:1 to 10:3, and the transparency gradually increases as the molar ratio of zinc to PVA increases. For example, N PVA :N Zn A cross-linking ratio of 10:2 or greater appears to initiate transparency. This can be attributed to the steric hindrance of zinc ions, which prevents PVA from undergoing physical cross-linking during freeze-thaw cycles. Changes in cross-linking density during the formation process are assessed by visual observation of optical transparency. For example, as... Figure 26 Specifically, the optical extinction at 550 nm was measured using an Agilent Cary 6000UV-Vis spectrophotometer for self-healing polymers prepared according to certain aspects of this disclosure with different metal-ligand molar ratios. Higher extinction indicates lower transparency of the material. The extinction values ​​of the original physically crosslinked PVA hydrogel without any metal ions and the self-healing polymer with a zinc ion to PVA ligand molar ratio of 10:3 were 2.79 and 0.25, respectively. Compared to the extinction of the original PVA hydrogel, the extinction of the self-healing polymer was reduced by approximately 91%. Therefore, it was indirectly assessed that zinc ions affect the reduction of the physical crosslinking density in the polymer. Figure 26 As shown, the optical extinction decreases quadratically with respect to the molar ratio of zinc ions to PVA ligands.

[0092] Figures 2A-2B Two types of complexes present within self-healing polymer materials are shown. Figure 2A Zn-PVA ligand complexes were shown to contribute to self-healing bonds in polymer materials, on the other hand, Figure 2B The Zn-H2O complex appears to inhibit the formation of dynamic bonds that promote self-healing. Figure 2AThe Zn-PVA complex is thought to play a crucial role in inducing ultrafast and autonomous self-healing properties in self-healing materials, while Zn-H₂O appears to be an inhibitory complex that interferes with the formation of the desired metal-polymer network. As discussed above, and not necessarily limitingly, assuming that zinc ions initially participate in the formation of the Zn-PVA complex, followed by the remaining zinc ions forming the Zn-H₂O complex, the ratio between the Zn-PVA and Zn-H₂O complexes can be at least 1:1 to 5:1. In other words, 83% of the zinc ions bind to the PVA ligands, and the remaining zinc ions (17%) subsequently form the Zn-H₂O complex. However, in cases where zinc ions simultaneously form both types of complexes, the amount of zinc ions involved in coordination with water molecules may increase.

[0093] Therefore, in some aspects, controlling the activation energy of a self-healing material can be achieved by controlling the amount of water in the self-healing material prepared according to certain aspects of this disclosure. In some embodiments prepared according to this disclosure, the activation energy can be controlled by a dehumidification process, such that the self-healing polymer comprises a cross-linked polymer network linked by a preferred Zn-PVA complex rather than a Zn-H2O complex. For example, by reducing the water content in the self-healing material (especially a PVA-Zn self-healing material), ultrafast self-healing can occur, for example, as noted above in some embodiments, with a self-healing time of less than about 10 minutes, or about 5 minutes, or about 1 minute, or about 10 seconds.

[0094] While this teaching is not limited to any particular theory, Figure 3 The diagram illustrates the bond structure in a self-healing material 20 prepared according to certain aspects of this disclosure, which is believed to be generated during a freeze-thaw process. Using a freeze-thaw process to form a self-healing polymer system according to certain aspects of this disclosure can produce films with greater processability (e.g., for forming mechanically robust standing films). Furthermore, the use of a freeze-thaw process facilitates the induction of the formation of covalently cross-linked networks, thereby producing... Figures 23A-23C The high chemical stability is demonstrated. It is noteworthy that, according to certain aspects of this disclosure, methods for manufacturing self-healing polymer systems may include combining a precursor of a polymer network (such as poly(vinyl alcohol)(PVA)) with a precursor of a transition metal (such as a zinc salt, such as zinc nitrate hexahydrate), which may be mixed together to distribute zinc ions throughout the polymer network. In some variations, the molar amount of PVA (N...) PVA ) and the molar ratio of zinc ions (N) ZnThe ratio of the polymer to the transition metal can be greater than or equal to about 20:1 to less than or equal to about 10:5, and in some variations, greater than or equal to about 10:1 to less than or equal to about 10:3. Additional reactions, such as crosslinking and bonding, may occur in some aspects. In one variation, a freeze-thaw cycle is included to facilitate the desired reactions, including condensation and crosslinking and coordination bond formation, which, when PVA is used, produces a hydrogel. Thus, the mixture of polymer and transition metal can be frozen, for example, at a temperature of -15°C for 24 hours. The fully frozen sample is then thawed, for example, at ambient conditions (e.g., room temperature of about 23°C) for 3 hours. This freeze-thaw process is repeated multiple times, for example, three times in three cycles, resulting in the formation of a Zn-PVA complex hydrogel. Furthermore, the self-healing polymer system can be further heated, for example, at a temperature in the range of greater than or equal to about 30°C to less than or equal to about 60°C. Additionally, the self-healing polymer system can be dried or dehumidified to remove water from the sample. For example, such a dehumidification process may include a dehumidification process in a dryer, which may have a temperature of about 22°C and a relative humidity of 17%. Depending on the amount of water to be removed, the process may take place for different durations, such as more than or equal to about 24 hours, optionally more than or equal to about 48 hours, and optionally more than or equal to about 72 hours.

[0095] Refer again Figure 3 As shown in the left box, after a freeze-thaw process, the pristine PVA hydrogel 10, containing no zinc ions, is primarily linked in the network via ether bonds 12. However, as can be seen in the structure on the right, when zinc ions are introduced and distributed within the PVA polymer matrix 20, the number of ether bonds 22 decreases with increasing Zn-PVA complex 24. PVA possesses ligands that define coordination sites 26 for transition metal ions corresponding to hydroxyl groups capable of coordinating with transition metals (such as Zn). Therefore, a majority of the hydroxyl groups in the PVA participate in coordination bonding 28 with metal ions, rather than hydrogen bonding with water molecules. Figure 3 As shown, some water molecules form Zn-H2O complexes 30, which are called inhibitory complexes because they can participate in hydrogen bonding with PVA 32. Therefore, when zinc is introduced into the polymer matrix, the inherent properties of the original PVA hydrogel (without zinc) are weakened in the presence of metal-ligand interactions.

[0096] Figure 4The self-healing time of self-healing polymer materials with different zinc to PVA molar ratios prepared according to certain aspects of this disclosure is shown. First, the sample is cut into two pieces to repeat any potential mechanical damage that may occur. Then, the two pieces are brought into contact with each other, which can also be done under an optionally applied pressure, for example, less than or equal to about 0.5 MPa or optionally less than or equal to about 0.1 MPa. Thus, contact and the optionally applied pressure bond and re-bond these parts together and promote metal-ligand interactions. The self-healing time is defined as the time during which the sample can be stretched to at least 200% elongation without any cracks in the healed area. After the specified self-healing time has been achieved, the cuts in the two sample pieces can spontaneously self-heal at elevated temperatures of 22°C (black circle) and 30°C (red circle). Figure 4 As shown by the black circles and lines, hydrogels produced using a three-cycle freeze-thaw process require a relatively long self-healing time of approximately 3 to 6 hours to recover from fractures to their initial state at room temperature. However, as... Figure 4 As shown by the red circle, the self-healing time of Zn-PVA hydrogel is significantly reduced when it is stored at an elevated temperature of 30°C for 10 minutes.

[0097] To further understand the effect of heating on self-healing efficiency, self-healing tests were conducted at various temperatures (30℃, 40℃, 50℃ and 60℃). Figure 5 This indicates the effect of heating temperature on the self-healing time of self-healing hydrogels prepared according to certain aspects of this disclosure. For example... Figure 5 As shown, when the Zn-PVA complex hydrogel was heat-treated at elevated temperatures (30℃, 40℃, 50℃, and 60℃) for 10 minutes, the self-healing time significantly decreased. This effect is attributed to the increased rate of the reaction that forms coordination bonds between zinc ions and ligands in PVA. According to the Arrhenius equation listed below, the kinetic constant increases with temperature, thereby activating the reaction that forms the Zn-PVA complex:

[0098]

[0099] Where k is a kinetic constant related to the self-healing rate, and E a As the activation energy, k BLet be the Boltzmann constant, and T be the absolute temperature. According to the Arrhenius equation, the rate of self-healing is controlled by temperature and activation energy. Generally, from a kinetic perspective, higher temperatures can lead to an increase in the reaction constant. Another effective way to increase the kinetic constant is to lower the activation energy. Therefore, the activation energy of certain self-healing polymers prepared according to this disclosure can be reduced by a dehumidification or water removal process. This result can be attributed to a reduction in the amount of Zn-H2O complexes that inhibit self-healing efficiency. It is believed that after the removal of water molecules, most zinc ions can participate in the formation of coordination bonds with PVA ligands, thereby enhancing the reversibility of breakage and reforming.

[0100] Figure 6 The effect of dehumidification on the self-healing efficiency of self-healing polymers prepared according to certain modifications of this disclosure is demonstrated. Figure 6 In the experiment, self-healing polymer samples of PVA-Zn hydrogel were formed. Samples that underwent three cycles of freeze-thaw cycles (black circles) are shown as black circles. Self-healing polymer samples formed through the same freeze-thaw process followed by heating at 60°C are shown as red circles. Finally, self-healing polymer samples formed through the same freeze-thaw process followed by a 72-hour dehumidification process in a desiccator set to 22°C and 17% RH are shown as blue circles.

[0101] The ability of self-healing polymers to undergo ultrafast self-healing is based on controlling the activation energy by removing water from the polymer (e.g., through dehumidification). On one hand, dehumidification can be achieved by storing a self-healing polymer sample at 22°C in a desiccator set to 17% relative humidity for 72 hours. Interestingly, as... Figure 6 The data (blue circles) shows that after dehumidification, when zinc (N...) Zn ) and PVA(N PVA When the molar ratio of ) is 0.3, the self-healing time is significantly reduced to about 5 to 10 seconds.

[0102] Figure 7 The self-healing time corresponding to the data of dehumidifying self-healing PVA-Zn polymer was summarized. Figure 6 (The blue circle shown in the image). This ultrafast self-healing ability can be attributed to the increase in the Zn-PVA complex, rather than the Zn-H2O complex, because water molecules within the hydrogel are removed through a dehumidification process. Water can act as a barrier to inhibit the reaction of zinc ions with the hydroxyl groups of PVA to form coordination bonds. Therefore, when the self-healing polymer has a large amount of water within the material, the activation energy (E) in the Arrhenius equation is higher. a The ) term will increase. From a kinetic perspective, the kinetic constant for the formation of Zn-PVA complexes increases with the removal of the water barrier.

[0103] Figure 8 and Figure 9 The data supports the hypothesis that dehumidification alters the activation energy. Figure 8 and Figure 9 The terms represent the relationship between the kinetic constant (k) and absolute temperature (T) of the self-healing polymer prepared according to certain aspects of this disclosure before and after dehumidification, based on the Arrhenius equation. Figure 8 The results show that the logarithm (ln(k)) of the self-healing rate constant of the self-healing polymer manufactured through three cycles of freeze-thaw without dehumidification is inversely proportional to the reciprocal of the absolute temperature (1 / T). Based on experimental data, the correlation between the rate constant and the reciprocal of temperature agrees well with the Arrhenius equation, where the activation energy (E... a ) corresponds to the slope of the linear fit. Figure 9 The self-healing rate constant of a self-healing polymer manufactured through a three-cycle freeze-thaw process followed by a 72-hour dehumidification process in a dryer set at 22°C and 17% RH is shown. This self-healing rate constant is inversely proportional to the absolute temperature. The activation energy, corresponding to the slope in the linear fit, shows different trends with varying molar ratios of zinc ions to polymer ligands. (As shown in...) Figure 9 and Figure 8 As observed, the slope gradually decreases with the increase of the metal-ligand molar ratio after dehumidification.

[0104] Figure 10 It shows from Figure 8 and Figure 9 The activation energy obtained with respect to the metal-ligand molar ratio. It is estimated that most zinc ions participate in the formation of Zn-PVA complexes, thereby contributing to improved self-healing efficiency of the self-healing polymer system by reducing the likelihood of Zn-H2O complex formation, which inhibits metal-polymer interactions. Therefore, in some variations, the activation energy of the self-healing system is controlled by the dehydration process. Thus, certain embodiments provided in this disclosure can achieve a reduction in activation energy by enhancing the interaction between metal ions and polymer ligands. The correlation between activation energy and the metal-ligand molar ratio satisfies the following expression: E a = a·f+b, where

[0105]

[0106] Among them, E a denoted as 'activation energy', f is the molar ratio between the number of metal ions and the number of ligands (polymers), a is the slope of the linear fit of the curve of activation energy versus metal-ligand molar ratio, and b is the y-intercept of the same curve, i.e., the activation energy of a self-healing polymer without any metal ions.

[0107] Figure 11 and Figure 12 Static tensile tests performed by dynamic mechanical analysis (DMA) revealed the mechanical properties of the self-healing polymer prepared according to certain aspects of this disclosure. Figure 11 and Figure 12 The stress-strain curves of the self-healing polymer before and after the removal of water molecules present in the sample are shown.

[0108] exist Figure 12 Under these conditions, the sample was stored for 72 hours in a desiccator set at 22°C and 17% RH. Figure 12 As shown, with N Zn / N PVA As the value increased from 0.1 to 0.3, the maximum tensile stress at the fracture point increased from 350% (black curve) to 1,150% (orange curve). Molar ratio (N) Zn / N PVA The lower the molar ratio, the higher the Young's modulus and tensile strength, due to a greater amount of ether-based physical crosslinking within the material. On the other hand, self-healing films with higher molar ratios of 2.5 or 3.0 tend to exhibit much lower Young's modulus and even higher elongation. Higher concentrations of zinc ions may interfere with the formation of physical crosslinks between the PVA backbone during freeze-thaw processes, thereby softening the hydrogel and reducing the Young's modulus.

[0109] Figure 13 This shows how the molar ratio of zinc to PVA changes from Figure 11 and Figure 12 The Young's modulus (E) of the obtained self-healing polymer. "Young's modulus" refers to the mechanical property of a given material as a ratio of stress to strain. One way to express the Young's modulus is through the following expression:

[0110]

[0111] Wherein, the engineering stress is σ, the tensile strain is ∈, E is Young's modulus, and L O For the equilibrium length, ΔL is the length change under applied stress, F is the applied force, and A is the area of ​​the applied force. However, other methods for calculating Young's modulus can also be used, as described below. The red and blue circles represent the modulus of the self-healing polymer before and after dehumidification in a desiccator (22°C / 17% RH) for 72 hours, respectively. Both groups of samples similarly show that the modulus decreases exponentially with increasing molar ratio. Figure 13As shown, the modulus of the dehumidified sample is two orders of magnitude higher than that of the water-containing sample. While this teaching is not limited to any particular theory, this phenomenon may be related to the inherent softness of hydrogels containing a large amount of water as a plasticizer. As water is removed, hydrogels generally become mechanically harder and stronger. This characteristic may appear in self-healing polymers provided by certain aspects of this disclosure, since these self-healing polymers are manufactured via a freeze-thaw process to form general hydrogels. Furthermore, the Young's modulus gradually decreases with increasing metal ion-ligand molar ratio. As previously mentioned, the steric hindrance of zinc ions interferes with the formation of networks covalently linked by ether bonds during the freeze-thaw process. In addition, most zinc ions begin to participate in the formation of Zn-PVA complexes by bonding with the hydroxyl groups of PVA, resulting in a relatively reduced number of ether covalent bonds. For these reasons, self-healing polymers prepared according to certain aspects of this disclosure show a decrease in Young's modulus with increasing metal-ligand molar ratio. In particular, the Young's modulus in self-healing polymers shows the following correlation with the metal-ligand molar ratio:

[0112] f = A·exp(-Bf)

[0113] Where E is Young's modulus and f is the molar ratio between the number of metal ions and the number of ligands (polymer). The criteria for the formation of ultrafast self-healing polymers A and B are likely around 2. Therefore, by controlling the moisture content and the molar ratio of metal ligands, the self-healing polymer exhibits a wide range of Young's moduli. This modulus tunability is based on the formation of a polymer network induced by coordination bonds, rather than covalent bonds, between zinc ions and the PVA backbone, thus creating potential applications for artificial skin or flexible electronics. Furthermore, the Young's modulus of the dehumidified self-healing polymer shows a range similar to that of human skin. Figure 13 The yellow boxes shown indicate the modulus range of human skin discussed in papers such as M. Jadams et al., Friction and lubrication of human skin, Tribology Letters, 26, 239, (2007) and C. Pailler-Mattéi et al., “Analysis of adhesive behaviour of human skin in vivo by anindentation test,” Tribology International, 39, 12, (2006), the relevant sections of which are incorporated herein by reference.

[0114] Figure 14This represents the brittle-ductile transition of a self-healing polymer based on a Zn-PVA complex subjected to a freeze-thaw and dehydration process. Although the tensile strength at the fracture point decreases with increasing molar ratio of zinc ions to PVA, the maximum elongation increases significantly. As mentioned above, zinc ions inhibit the formation of covalent bonds (ether bonds) during the freeze-thaw process due to the steric hindrance of zinc. Furthermore, zinc ions form a polymer network comprising polymer chains crosslinked through coordination bonds with the hydroxyl groups of PVA. This polymer network based on metal-polymer ligand interactions significantly improves the elongation properties of the self-healing film. Therefore, as... Figure 14 As shown, this brittle-ductile transition with varying molar ratio of metal ligands was observed in self-healing polymers. In contrast, conventional hydrogels formed through a freeze-thaw process (e.g., pristine PVA hydrogels without metal ions) exhibit strong physical crosslinking with hydrogen bonds. Thus, pristine PVA hydrogels can be formed via hydrogen bonds, ether-like covalent bonds, and physical crosslinking. These supramolecular physical bonds within the hydrogel contribute to improved mechanical properties, such as modulus and tensile strength. Therefore, hydrogels based on physical crosslinking and hydrogen bonds formed through a freeze-thaw process exhibit strong mechanical properties, then become more brittle with gradual evaporation of water. Therefore, this brittle-ductile transition observed in self-healing polymers prepared according to certain aspects of this disclosure can be attributed to metal-ligand interactions in the presence of zinc ions.

[0115] Figure 15 These are a series of photographs taken in the case of a self-healing polymer system prepared according to certain aspects of this disclosure being cut, then reattached and healed. Figure 15 The results show that the self-healing polymers containing PVA and Zn exhibit autonomous and ultra-fast self-healing properties under environmental conditions and without slight manual pressure, with self-healing occurring without any external stimuli (e.g., heat, light, and solvents). Samples prepared by undergoing three cycles of freeze-thaw cycles followed by a 72-hour dehumidification process in a desiccator set to 22°C and 17% RH possess PVA and Zn... 2+ The molar ratio is 10:3. The self-healing time is approximately 10 seconds, after which the healed sample can be stretched to over 200% strain.

[0116] Figure 16 A self-healing polymer system comprising PVA and Zn, prepared according to certain aspects of this disclosure, exhibits an ultra-high elongation of 4000% at a very low strain rate (approximately 10 mm / min). PVA and Zn 2+ The self-healing polymer with a molar ratio of 10:3 was produced by undergoing a freeze-thaw cycle of 3 cycles, followed by a 72-hour dehumidification process in a dryer set at 22°C and 17% RH.

[0117] Figure 17 Scratch test results are shown for a self-healing polymer system with a thickness of 300 μm, laminated on a 1.1 mm thick glass substrate, prepared according to certain aspects of this disclosure. This self-healing polymer was prepared by undergoing three cycles of freeze-thaw cycles, followed by a 72-hour dehumidification process in a desiccator set to 22°C and 17% RH. Scratches were created by manually rubbing the 300 μm thick film with a razor blade. Without any intervention or stimulation, the damage began to self-heal, and the scratches almost disappeared within 5 minutes at room temperature. When the damaged surface was continuously rubbed with fingers, the scratches completely disappeared. Therefore, the self-healing polymer prepared according to certain aspects of this disclosure exhibits excellent scratch resistance as an anti-scratch coating suitable for automotive, construction, display, and electronic products.

[0118] Figure 18 Measurements of normal adhesive stress in self-healing polymer systems in the form of self-healing adhesives (SHAs) prepared according to certain aspects of this disclosure are presented. All samples were prepared by undergoing a three-cycle freeze-thaw process followed by a 72-hour dehumidification process in a desiccator set at 22°C and 17% RH. The prepared SHA films, with a thickness of 200 μm, were preloaded and laminated onto 1.1 mm glass to evaluate the performance of the pressure-sensitive adhesive (PSA). The adhesive strength initially increased monotonically with preload, then showed a saturation value starting from a preload of approximately 2 MPa. With a preload of 2.55 MPa, the adhesive strength of the SHA was approximately 67.4% higher than its inherent adhesive strength, which represents the adhesive strength of the SHA without any preload. The measured adhesive strengths (black circles) are consistent with the following fitted model:

[0119]

[0120] Where, σ A The total adhesive strength, The normal bond strength, as an inherent material property, is the bond strength without any preload. Let P be the saturation value of the normal bond strength under preload, and τ be the relaxation bond strength with preload τ. The intrinsic bond strength of SHA is extracted from the measured data. The value is 0.19 MPa, and then it is calculated through equation fitting. τ and τ are 0.13 MPa and 0.6 MPa, respectively. Therefore, the ultrafast self-healing adhesive form prepared according to certain aspects of this disclosure exhibits the special properties of a pressure-sensitive adhesive (PSA) that follows the above equation.

[0121] Furthermore, the SHA prepared according to certain aspects of this disclosure exhibits superior performance compared to commercially available products (3M Scotch). Tape810) and such Figure 18 The biomimetic Gecko patterned physical adhesive shown exhibits stronger adhesive strength than the 3MScotch adhesive. Tape 810 is described in S. Fujii et al., “Pressure-sensitive adhesive powder,” Mater. Horiz., 3, 47 (2016), and the biomimetic Gecko patterned physical adhesive is described in SH Leeee et al., “Scalable and continuous fabrication of bio-inspired dry adhesives with a thermosetting polymer,” Soft Matter, 14, 2586 (2018). Relevant portions of both documents are incorporated herein by reference. The bond strengths of 3M Scotch Magic Tape and Gecko patterned dry adhesive are 0.15 MPa and 0.112 MPa, respectively.

[0122] Figure 19 Photographs are shown to observe the adhesion properties of a self-healing adhesive (SHA) prepared according to certain aspects of this disclosure to different substrates. More specifically, the SHA is a Zn-PVA complex formed by a three-cycle freeze-thaw process followed by a 72-hour dehumidification process in a desiccator set at 22°C and 17% RH. The SHA provides excellent adhesion to various interfaces, such as metal to glass, metal to metal, and metal to plastic. For example, the SHA enhances its adhesion to glass due to the presence of coordinate bonds.

[0123] In some respects, this disclosure therefore envisions a self-healing pressure-sensitive adhesive formed from a self-healing polymer material, wherein the adhesive bonds to at least one substrate selected from the group consisting of glass, plastics, metals, fabrics, and biological tissues (such as skin). In some variations, the bond strength of the PSA to at least one substrate is greater than or equal to about 0.05 MPa without any preload and 0.15 MPa at a preload level of 1.5 MPa. For example, the bond strength may be 0.190 ± 0.006 MPa without any preload and 0.303 ± 0.006 MPa at a preload level of 1.4 MPa. The normal stress of the self-healing adhesive as the bond strength is measured by FDHT (Larson System Inc.) to evaluate the properties of the pressure-sensitive adhesive (PSA) with and without preload. The self-healing adhesive is laminated onto a metal stamp with a diameter of 1.5 cm. The metal stamp is moved vertically downwards and then bonded to the substrate with or without preload, depending on the experimental conditions. Then, the force or stress is measured as the metal embossing machine moves upward, and the maximum normal stress is recorded before the embossing machine is completely separated from the substrate.

[0124] Figures 27A-27C The measurements of shear strength of self-healing polymers prepared according to certain aspects of this disclosure are shown based on ASTM D1002. Figure 27A A comparison of the time-varying shear strength of double-sided tape, commercially available pressure-sensitive adhesive, and self-healing polymers prepared according to certain aspects of this disclosure is shown. Figures 27B-27C This shows how shear strength was measured during the test and the INSTRON used. TM Ultimate tensile testing machine. PVA and Zn 2+ A self-healing polymer with a molar ratio of 10:3 was produced by undergoing a three-cycle freeze-thaw process, followed by a 72-hour dehumidification process in a dryer set at 22°C and 17% RH. Then, it was processed at INSTRON. TM Shear strength was measured on an ultimate tensile testing machine according to ASTM D1002. This was compared to a commercially available product (3M Scotch) with a shear strength of 18.94 kPa. Compared to the shear strength of commercially available PSA (3M OCA) with a shear strength of 31.69 kPa (Tape 810), the self-healing polymer has a maximum shear strength of approximately 111.30 kPa. Therefore, the self-healing polymer prepared according to certain aspects of this disclosure exhibits excellent shear strength as a pressure-sensitive adhesive.

[0125] Figures 20A-20BA schematic diagram of the chemical structure of a self-healing adhesive (SHA) prepared according to certain aspects of this disclosure when bonded to a glass substrate containing silicon oxide is shown. Figure 20A As shown, metal-ligand complexes can form coordination bonds with ligand sites (Si-O-) provided by glass (M. Tupy et al. Effect of water and acid-base reactants on adhesive properties of various plasticized poly(vinylbutyral) sheet, J. Appl. Polym. Sci. 127, 3474 (2013), the relevant portion of which is incorporated herein by reference). Therefore, a non-limiting hypothesis is that the adhesion between SHA and glass may be due to coordination bonds between metal ions within SHA and ligand sites present on the glass surface, such as... Figure 20B As shown.

[0126] Figures 21A-21B The self-healing properties of a pressure-sensitive adhesive (PSA) prepared according to certain aspects of this disclosure are shown, and more specifically, the self-healing properties of the SHA with respect to adhesive strength are shown. Figure 21A As shown, the self-healing adhesive was cut into two pieces and then allowed to self-heal for 10 minutes. The self-healing adhesive was then bonded to a glass substrate using a preload to test the bond strength. Figure 21A The image shows the SHA layer being cut in half and then self-healing at room temperature for 10 minutes without any stimulation. Then, it was used with... Figure 18 The same method used to evaluate the adhesive strength of the self-healing SHA is shown in the PSA assessment. Figure 21B The relationship between adhesive strength and preload is shown before and after self-healing. It can be seen that the adhesive strength of samples tested before and after the self-healing process is very similar.

[0127] according to Figure 21B The equations shown indicate that the self-healing SHA exhibits the same behavior as the pre-damage SHA. The relaxation strengths (τ) of the initial SHA and the self-healing SHA before damage are 0.60 MPa and 0.66 MPa, respectively. As a non-limiting assumption, the approximately 10% difference in relaxation strength between the initial SHA and the self-healing SHA may be due to the approximately 10% additional preload required to achieve 1 / e bond strength in the case of the self-healing SHA. In some aspects, this disclosure provides conditions for the ratio of the two relaxation strengths between the initial SHA and the self-healing SHA to form an ultrafast self-healing adhesive.

[0128] Figure 22Stress-strain curves representing the self-healing behavior of a self-healing adhesive (SHA) prepared according to certain aspects of this disclosure are shown. PVA and Zn 2+ SHA with a molar ratio of 10:3 was prepared by undergoing a freeze-thaw cycle of 3 cycles, followed by a dehumidification process for 72 hours in a dryer set at 22°C and 17% RH. The initially undamaged membrane exhibited a maximum elongation of 1107% in the DMA test. Another membrane, manufactured under the same conditions, was cut into two pieces and placed in contact with each other through the damaged surfaces. After healing at room temperature for approximately 10 minutes without any intervention or stimulation, the joined membrane retained approximately 1056% of its strain in the scratch test in the DMA, with a healing efficiency of approximately 95%, except for the optional application of a pressure of less than or equal to about 0.5 MPa, and optionally less than or equal to about 0.05 MPa. The damage initiated self-healing, and the maximum elongation recovered to almost 90% of the initial elongation before the damage. This behavior is thought to be attributable to the metal-ligand coordination bonds in the polymer matrix.

[0129] Figures 23A-23C The sealing performance and durability of an adhesive joint formed by a self-healing adhesive (SHA) prepared according to certain aspects of this disclosure are demonstrated. A 500 μm thick glass slide and glass bottle are filled with deionized water, isopropanol (IPA), acetone, dimethylformamide (DMF), and benzene, and the slide and glass bottle are sealed with an SHA membrane. Figure 23A The settings are shown in the image. After sealing for 5 minutes, the slide is placed on the bottom side and then stored for 15 days. See comparison... Figure 23B and Figure 23C As shown, the sealed SHA exhibits excellent solvent resistance: when the bottle was filled with water, IPA, acetone, DMF, and benzene, no leakage was observed after 15 days of standing. This demonstrates that SHA has good solvent resistance and is particularly suitable as a leak-proof sealant. Therefore, in some aspects, this disclosure envisions a self-healing pressure-sensitive adhesive that is stable in the presence of solvent erosion and is solvent-resistant (i.e., solvent-resistant). In other aspects, this disclosure therefore envisions a self-healing pressure-sensitive adhesive that is stable and water-resistant in the presence of water. These self-healing polymeric materials can be applied when the substrate has solvents or water disposed thereon. Therefore, when the self-healing polymeric materials are pressure-sensitive adhesives, they can be used to bond wet substrates together.

[0130] Figure 24 The optical transmittance spectrum of a self-healing adhesive (SHA) prepared according to certain aspects of this disclosure is shown. Due to diffuse reflection caused by the rough surface of the SHA film, the SHA film exhibits a transmittance of approximately 78%. However, the SHA film sandwiched between two 1.1 mm thick glass substrates has a transmittance of approximately 92%, which is significantly lower than that of the SHA film sandwiched between two 1.1 mm thick glass substrates. Figure 24The transmittance of the bare glass observed was almost identical. The measured haze was approximately 0.6%, resulting in an optically transparent self-healing polymer. This optical transparency of the self-healing polymer / SHA is due to the presence of metal-ligand coordination bonds in the polymer matrix. The steric hindrance of zinc ions inhibits the formation of ether covalent bonds during the freeze-thaw process. The initial PVA hydrogel, without any metal ions and associated with a covalent cross-linked network and hydrogen bonds, exhibited optical opacity. Therefore, the addition of zinc ions to the PVA ligands increases the coordination bond density, thereby improving optical transparency.

[0131] In some aspects, the self-healing polymer system may optionally be optically transparent or optically transmissive to electromagnetic radiation in the visible spectrum (e.g., light wavelengths in the range from about 380 nm to less than or equal to about 780 nm). Transparency means that the self-healing polymer system transmits electromagnetic energy to a target wavelength range (e.g., within the visible wavelength range). The self-healing polymer systems of this disclosure are capable of transmitting selected portions of the electromagnetic spectrum and therefore may be transparent or translucent. Transparency can generally encompass translucency and is generally understood to mean that light / energy of a predetermined target wavelength or wavelength range (which may be polarized or unpolarized) passes through the self-healing polymer system. In some variations, about 50% or more of the target wavelength (or wavelength range) passes through the self-healing polymer system, optionally about 60%, optionally about 70%, optionally about 75%, optionally about 80%, optionally about 85%, optionally about 90%, and in some variations, optionally about 92% or more of the target wavelength passes through the self-healing polymer system of this disclosure.

[0132] Figure 25 The conductivity of a self-healing adhesive (SHA) prepared according to certain aspects of this disclosure is shown. SHA is an ionomer based on metal-ligand coordination bonds. The reciprocal of the measured resistance (black circle) agrees well with the fitting model (red line) based on percolation theory, which can be expressed as follows:

[0133]

[0134] Among them, R -1 The reciprocal of the resistance of the self-healing adhesive. The maximum value of the reciprocal of the resistance of the self-healing adhesive, where f is the molar ratio of zinc to PVA. C Here, is the percolation threshold, and r is the critical exponent. In some respects, this disclosure envisions a self-healing polymer system with conductive properties satisfying the following performance equation representing the ionomer's properties: 0 < f C<0.1 and 1 < r < 2. This ionomer behavior of SHA can provide potential applications in ionic conductors, polymer electrolytes, and sensors.

[0135] The self-healing polymer systems of this disclosure can be conductive, and the sheet resistance is less than or equal to about 10 MΩ / square, optionally less than or equal to about 9 MΩ / square, less than or equal to about 8 MΩ / square, and in some variations optionally less than or equal to about 7 MΩ / square. This ionomer-like behavior of the self-healing polymers provided in this disclosure makes them suitable for use as stretchable sensors and solid electrolytes.

[0136] Furthermore, self-healing adhesives (SHAs) prepared according to certain aspects of this disclosure represent a potential application of novel self-healing materials. SHAs can repair adhesive joints and autonomously heal cracks after damage. Specifically, pressure-sensitive adhesives (PSAs) with self-healing capabilities are widely applicable as a special class of polymer adhesives. PSAs are used in components across many fields, including displays, flexible packaging, and electronics. PSAs are quasi-reversible adhesives that can bond to various substrates under pressure. PSAs exhibit viscoelasticity due to their low glass transition temperature, allowing them to maintain tackiness and flexibility. However, most conventional PSAs tend to be brittle and susceptible to mechanical, chemical, and thermal damage. Therefore, robust, damage-resistant PSAs with self-healing capabilities are needed. As described above, the ultrafast self-healing polymers based on dynamic and reversible metal-ligand interactions provided by certain aspects of this disclosure are particularly suitable for a variety of technical and commercial applications, including PSAs.

[0137] In some aspects, this disclosure envisions a self-healing polymer material comprising a polymer network containing one or more ligands having transition metal ion coordination sites. The self-healing polymer material further comprises transition metal ions distributed within the polymer network and capable of interacting with the transition metal ion coordination sites via coordination bonds. Such a self-healing polymer material can satisfy the following condition: E a = a·f+b; and Where Ea is the activation energy, f is the molar ratio of the transition metal ion to the ligand, a is the slope of the activation energy versus the molar ratio (e.g., the slope is linearly fitted), a is in the range of greater than or equal to about 1 to less than or equal to about 5, and b is the y-intercept of the activation energy versus the metal-ligand molar ratio. Therefore, "b" represents the activation energy of the self-healing polymer without any metal ions, and the value of b exceeds 0.2 eV. The polymer network is capable of self-healing mechanical cracks or cuts under ambient conditions within less than or equal to about 30 minutes.

[0138] In some other respects, this self-healing polymer material can have a Young's modulus expressed as: E = A·exp(-Bf), And A > 1, where E is Young's modulus and f is the ratio of the molar amount of transition metal ions to the molar amount of ligands in the polymer network.

[0139] On one hand, the self-healing polymer material has a Young's modulus (E) greater than or equal to about 0.01 kPa and less than or equal to 100 kPa, optionally greater than or equal to about 10 kPa and less than or equal to 100 kPa. On some other aspects, the self-healing polymer material is cross-linked and has a Young's modulus greater than or equal to about 1 kPa and less than or equal to 100 MPa, optionally greater than or equal to about 1 kPa and less than or equal to 50 MPa.

[0140] In other variations, this disclosure envisions a self-healing pressure-sensitive adhesive formed from such a self-healing polymer material, wherein the total adhesive strength (σ) of the self-healing pressure-sensitive adhesive is... A It can be expressed by the following formula: Where, σ 0 A σ represents the normal bond strength of a self-healing pressure-sensitive adhesive without any preload. 0 A，P Let P be the saturation value of the normal bond strength of the self-healing pressure-sensitive adhesive under preload, P be the preload applied to the self-healing pressure-sensitive adhesive, and τ be the relaxation bond strength under preload. In some respects, τ is greater than or equal to about 0.1 and less than or equal to about 1.

[0141] In other respects, the ratio of τ after self-healing to the initial τ before any damage is represented by the following: Where, τ 初始 τ represents the relaxation strength before damage. 自愈合 The relaxation strength after self-healing.

[0142] On the one hand, the total adhesive strength (σ) of self-healing pressure-sensitive adhesives. A The pressure can be greater than or equal to about 0.1 MPa to less than or equal to about 5 MPa, and optionally greater than or equal to about 0.01 MPa to less than or equal to 1 MPa.

[0143] In other respects, self-healing polymer materials possess ionomer properties as described below: Among them, R -1 The reciprocal of the measured resistance. is the maximum value of the reciprocal of the resistance of the self-healing adhesive, f is the ratio of the molar amount of transition metal ions to the molar amount of ligands in the polymer network, f is the percolation threshold, which is greater than 0 and less than or equal to about 0.1, and r is the critical exponent, which is greater than or equal to about 1 and less than or equal to about 2.

[0144] In various other aspects, this disclosure provides a method for manufacturing a self-healing polymer material. The method may include mixing a polymer precursor and a precursor containing a transition metal to form a mixture of a polymer and transition metal ions distributed in the polymer, the polymer having one or more ligands having at least one coordination site for a transition metal ion. The method further includes: freezing the mixture; and thawing the mixture. This forms a self-healing material comprising a polymer network having transition metal ions distributed therein. At least one transition metal ion coordination site on one or more ligands of the polymer network reacts with the transition metal to form a reversible coordination bond. The self-healing material is capable of self-healing mechanical cracks or cuts under ambient conditions in the absence of external stimulation within approximately 30 minutes.

[0145] In some aspects, at least three cycles of freezing and thawing are performed. In some other aspects, the method further includes a dehydration process on the self-healing material after thawing. The activation energy of the self-healing material is controlled by the amount of water removed during the dehydration process. In other aspects, the method may also include subjecting the self-healing material to a temperature greater than or equal to about 30°C and less than or equal to about 60°C after thawing.

[0146] It should be understood that while the above discussion pertains to a variation involving reversible metal-ligand bonding, the self-healing mechanism can be extended to include weak covalent and ionic bonds that can break and reform under mild conditions. In one embodiment, thiol-metal bonds (e.g., -S=Au, -S=Ag), which are generally considered to be covalent bonds, can spontaneously form. These bonds are formed by first dissociating the SH bond, which is advantageous in alkaline environments and inhibited under acidic conditions. Therefore, the thiol-metal bonds formed are expected to break in acidic environments. When the thiol moiety is contained on the polymer chain and gold (Au) nanoparticles are contained within the polymer matrix, self-healing can be established through the breaking and reforming of the thiol-gold bonds. Therefore, this disclosure contemplates not only self-healing polymer systems but also self-healing polymer composite systems having multiple particles (such as metal particles) distributed therein.

[0147] Example

[0148] The ultrafast self-healing polymer based on the Zn-PVA complex was produced using the freeze-thaw method described in C. Hassan et al., “Structure and Applications of poly(vinyl alcohol)hydrogels produced by conventional crosslinking or by freezing / thawing methods,” Adv. Polym. Sci. 153, 37 (2000) (the relevant portion of which is incorporated herein by reference). Therefore, 10 g of PVA (Sigma-Aldrich, Mw approximately 89,000 g / mol, >99% hydrolyzed) was dissolved in 100 ml of deionized water and vigorously stirred with a magnetic rod at 90 °C for 1 hour. The mixed solution was then cooled to room temperature. For metal-ligand complexation, zinc nitrate hexahydrate (Zn(NO3)2·6H2O) was selected as the Zn... 2+ The source is the good solubility of zinc nitrate hexahydrate in water and its thermal stability in the solid state. Zinc nitrate hexahydrate (Sigma-Aldrich, purity Pa, crystallinity >99%, Mw ~ 297.49 g / mol) was added to a prepared 10 wt.% PVA solution at a molar ratio (N... PVA :N Zn The ratios of the homogeneous aqueous solutions were 10:1, 10:1.5, 10:2, 10:2.5, and 10:3, and then mixed for an additional hour at 25°C using a magnetic rod. Each of these prepared homogeneous aqueous solutions was poured into polycarbonate petri dishes of the desired size and then frozen at -15°C for 24 hours. The fully frozen samples were thawed at room temperature for 3 hours. This freeze-thaw process was repeated three times (in three cycles), resulting in the formation of Zn-PVA complex hydrogels. Finally, at least five groups of samples identical to those prepared using the above procedure were prepared to evaluate a material property. To investigate the effect of temperature on self-healing efficiency, some groups of samples were evaluated when heated at 30°C, 40°C, 50°C, and 60°C compared to ambient conditions (room temperature, typically around 23°C).

[0149] Similarly, other groups of samples were placed in a desiccator to remove residual water present within the self-healing polymer and to increase the Zn-PVA complex by reducing the Zn-H₂O complex. The humidity and temperature observed within the desiccator were 17 ± 2% RH and 22 ± 1 °C, respectively. These dehumidified samples were prepared to analyze the effect of moisture on self-healing efficiency. Self-healing efficiency was evaluated by measuring the time it took for each sample to exhibit 200% elongation in the healed region without any cracks during self-healing under given conditions. Samples had an initial length of 10 mm and were then elongated using a domestically produced tensile testing machine. Dynamic mechanical analysis measurements were performed on a Dynamic Mechanical Analyzer RSA3 (strain rate approximately 0.2 mm / sec) to evaluate the mechanical properties of the self-healing polymer, such as Young's modulus, tensile strength, and maximum elongation. Normal bond strength was measured by FDHT (Larsen Systems) to evaluate the properties of the pressure-sensitive adhesive (PSA) with preload applied to the samples. Optical transmittance and haze were evaluated using an Agilent Cary 6000UV / Vis spectrophotometer and an Ocean Optics spectrophotometer. Shear strength was measured by INSTRON. TM Ultimate tensile testing was performed using a tensile testing machine that employs the standard set forth in ASTM D1002, the relevant portions of which are incorporated herein by reference.

[0150] Therefore, this disclosure envisions a self-healing polymer in which a reversible network of dynamic metal-ligand interactions can be strategically manipulated through activation energy control. The self-healing efficiency of the materials described herein is directly related to the control of the activation energy, which can be achieved by adjusting the moisture or water content within the product. Furthermore, the mechanical and adhesive properties of the self-healing polymer materials can be tuned not only by changing material parameters (such as the ligand / metal ratio, polymer molecular weight, and degree of hydrolysis) but also by changing process parameters during formation (involving the number of freeze-thaw cycles, temperature, and humidity). Following mechanical damage, these dynamically coordinated elastomers exhibit excellent self-healing capabilities under ambient conditions without any intervention. Additionally, as an alternative, self-healing can be used in other systems, including weak covalent and ionic bonds that can break and reform under mild conditions, such as gold-thiol bonds. The self-healing polymer materials provided in certain aspects of this disclosure can be used in a variety of non-limiting applications, including electronics, displays, wearable devices, vehicles, robotic arms, manufacturing, construction, medical devices and surgical applications, flexible packaging, toys, sensors, and electrolytes (e.g., electrolytes for energy storage and conversion devices). In some aspects, the self-healing polymer materials can be molded to form structural components or used to form layers or coatings disposed on other materials. As described above, the self-healing polymer materials can form pressure-sensitive adhesives that can bond or bond two substrates together.

[0151] For illustrative and descriptive purposes, the foregoing description of the embodiments has been provided. This description is not intended to be exhaustive or limiting of this disclosure. Various elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable and may be used in selected embodiments where applicable, even if not specifically shown or described. The same parts may also be varied in various ways. These variations should not be considered as departing from this disclosure, and all such modifications are intended to be included within the scope of this disclosure.

Claims

1. A self-healing polymer material, said self-healing polymer material comprising: A polymer network comprising a polymer of poly(vinyl alcohol) defining one or more ligands having transition metal ion coordination sites, wherein, The polymer network contains no other polymers and the transition metal ion is zinc ion (Zn). 2+ And the molar N of hydroxyl groups in the poly(vinyl alcohol) PVA The molar N of the zinc ions Zn The ratio is 10:1 to 10:3; and Transition metal ions, which are distributed in the polymer network and are capable of interacting with the coordination sites of the transition metal ions through reversible coordination bonds, wherein the polymer network is capable of self-healing mechanical cracks or cuts under environmental conditions within 30 minutes or less.

2. The self-healing polymer material according to claim 1, wherein, The polymer network is capable of self-healing mechanical cracks or cuts within 1 minute or less under environmental conditions.

3. The self-healing polymer material according to claim 1, wherein, The polymer network also includes additives selected from the group consisting of plasticizers, crosslinking agents, nanoparticles, and combinations thereof.

4. The self-healing polymer material according to claim 1, wherein, The polymer network is a hydrogel.

5. The self-healing polymer material according to claim 1, wherein, The molar N of hydroxyl groups in the poly(vinyl alcohol) PVA The molar N of the zinc ions Zn The ratio is 10:

2.

6. The self-healing polymer material according to claim 1, further comprising: water; a first complex of the transition metal ion and the coordination site of the transition metal ion; and a second complex of the transition metal ion and water, wherein, The ratio of the first complex to the second complex is greater than or equal to 1:1 and less than or equal to 5:

1.

7. The self-healing polymer material according to claim 1, wherein the self-healing polymer material is capable of having a strain elongation greater than or equal to 100% after the self-healing of the mechanical crack or cut.

8. The self-healing polymer material according to claim 1, wherein the self-healing polymer material has a transmittance of greater than or equal to 70% for electromagnetic radiation wavelengths greater than or equal to 380 nm to less than or equal to 780 nm.

9. The self-healing polymer material according to claim 1, wherein the self-healing polymer material has a sheet resistance of less than or equal to 10 MΩ / square.

10. A self-healing pressure-sensitive adhesive formed from the self-healing polymer material of claim 1, wherein, The self-healing pressure-sensitive adhesive can bond to at least one substrate selected from the group consisting of glass, plastic, metal, fabric, and biological tissue.

11. The self-healing pressure-sensitive adhesive according to claim 10, wherein the bonding strength between the self-healing pressure-sensitive adhesive and the at least one substrate is greater than or equal to 0.05 MPa without any preload, and 0.15 MPa at a preload level of 1.5 MPa.

12. The self-healing pressure-sensitive adhesive according to claim 11, wherein the self-healing polymer material is water-resistant and solvent-resistant.

13. The self-healing pressure-sensitive adhesive according to claim 11, wherein the self-healing polymer material has a maximum shear strength greater than or equal to 100 kPa.

14. A device comprising the self-healing polymer material of claim 1, wherein, The device is selected from the group consisting of: electronic equipment, vehicles, manufacturing equipment, construction equipment, medical equipment, packaging, toys, and energy conversion or storage devices.

15. The device according to claim 14, wherein, The electronic device is selected from the group consisting of displays, wearable devices, and sensors, and the manufacturing equipment includes a robotic arm.

16. A self-healing polymer material, said self-healing polymer material comprising: A polymer network comprising a polymer of poly(vinyl alcohol) having one or more ligands containing transition metal ion coordination sites, wherein, The polymer network contains no other polymers; and Transition metal ions, wherein the transition metal ions are zinc ions (Zn). 2+ The transition metal ions are distributed in the polymer network and can interact with the coordination sites of the transition metal ions through coordination bonds, and the self-healing polymer material satisfies the following conditions: ； and Among them, E a The activation energy is given by f, the molar ratio of the number of transition metal ions to the number of ligands is given by a, the slope of the activation energy to the molar ratio is given by a, which is in the range of greater than or equal to 1 to less than or equal to 5, and b is the y-intercept of the activation energy to the metal-ligand molar ratio. The polymer network is capable of self-healing mechanical cracks or cuts under ambient conditions within 30 minutes or less.

17. The self-healing polymer material according to claim 16, wherein the self-healing polymer material has a Young's modulus E greater than or equal to 0.01 kPa and less than or equal to 100 kPa.

18. The self-healing polymer material according to claim 16, wherein, The self-healing polymer material is cross-linked and has a Young's modulus greater than or equal to 1 kPa and less than or equal to 100 MPa.

19. A self-healing pressure-sensitive adhesive formed from the self-healing polymer material of claim 16, wherein, The total adhesive strength of the self-healing pressure-sensitive adhesive Greater than or equal to 0.1 MPa to less than or equal to 5 MPa.

20. The self-healing pressure-sensitive adhesive according to claim 19, wherein the self-healing pressure-sensitive adhesive has ionomer properties represented by the following: ,in, R -1 The reciprocal of the measured resistance. The maximum value of the reciprocal of the resistance of the self-healing adhesive, f is the ratio of the molar amount of transition metal ions to the molar amount of ligands in the polymer network, f C is the percolation threshold, which is greater than 0 and less than or equal to 0.1, and r is a critical exponent greater than or equal to 1 and less than or equal to 2.

21. A method for manufacturing a self-healing polymer material, the method comprising: Poly(vinyl alcohol) polymer precursor and zinc ion-containing Zn 2+ Transition metal precursors are mixed together to form a polymer and a mixture of transition metal ions distributed in the polymer, the polymer having one or more ligands having at least one transition metal ion coordination site; Freeze the mixture; and The mixture is thawed to form a self-healing material comprising a polymer network containing zinc ions (Zn) distributed therein. 2+ The polymer is composed of poly(vinyl alcohol) of the transition metal ion, wherein the polymer network is free of other polymers and at least one coordination site of the transition metal ion on one or more ligands of the polymer network reacts with the transition metal to form a reversible coordination bond, wherein the self-healing material is capable of self-healing mechanical cracks or cuts under environmental conditions without external stimulation within 30 minutes or less.

22. The method according to claim 21, wherein, The freezing and thawing are performed in at least three cycles.

23. The method according to claim 21, wherein the self-healing material is subjected to a dehydration process after thawing, wherein, The activation energy of the self-healing material is controlled by the amount of water removed during the dehydration process.

24. The method according to claim 21, further comprising: After thawing, the self-healing material is subjected to a temperature greater than or equal to 30°C and less than or equal to 60°C.

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