Preparation method of polymer film / hydrogel composite material with wrinkled surface

Abstract

The invention relates to the technical field of composite material preparation, in particular to a preparation method of a polymer film / hydrogel composite material with a wrinkled surface. The preparation method of the polymer film / hydrogel composite material with the wrinkled surface comprises the steps that hydrogel comprises a first surface and a second surface which are oppositely arranged, the first surface adheres to a substrate, the second surface is coated with a polymer solution, and the polymer film / hydrogel composite material is obtained through light curing treatment and drying treatment in sequence; and soaking the polymer film / hydrogel composite material in water to obtain the polymer film / hydrogel composite material. By controlling the raw materials, the hydrogel thickness, the soaking treatment time and the like, the fold wavelength and amplitude of the polymer film / hydrogel composite material can be accurately regulated and controlled, and the requirements of different application scenes can be met.

Description

Technical Field

[0001] The invention relates to the technical field of composite material preparation, and in particular to a method for preparing a polymer film / hydrogel composite material with wrinkled surface. Background Art

[0002] Hydrogels are three-dimensional soft materials composed of hydrophilic polymer networks. Due to their high water content, tunable mechanical properties, and excellent biocompatibility, they exhibit enormous potential for application in biomedicine, flexible sensing, microfluidic chips, optical manipulation, and information encryption. Research has shown that creating wrinkled structures on the surface of hydrogels allows for precise control of properties such as wettability, adhesion, conductivity, and impact resistance, potentially offering important applications in flexible electronics, biointerface engineering, and intelligent camouflage.

[0003] At present, the construction of surface wrinkled structures of hydrogels usually relies on mechanical pre-stretching or interfacial modulus mismatch, but these methods often require complex external field control or strict preparation conditions, which limits the programmability and environmental adaptability of the material. For example, the Chinese patent application with publication number CN118530494A discloses a core-shell structure polymer particle with a wrinkled surface and its preparation method and application. After the dried water-absorbing resin beads are fully swollen by water, they are placed in a carbon source aqueous solution, soaked and adsorbed to a layer of film, and then dehydrated and shrunk to a dry state to obtain core-shell structure polymer particles with a wrinkled surface. This patent application is only applicable to specific core-shell systems, and it is difficult to achieve dynamic control of micron-level wrinkle morphology. The Chinese patent application with publication number CN110105593A discloses a method for preparing a surface wrinkled alginate / polyacrylamide composite hydrogel. The surface wrinkled composite hydrogel is prepared by pre-stretching a calcium ion cross-linked alginate / polyacrylamide hydrogel and then soaking it in an aqueous solution of ferric chloride. This patent application relies on the application of external stress, has high requirements for the strength and direction control of pre-stretching, and is complex to operate.

[0004] Therefore, developing a new method for constructing hydrogel surface wrinkle structure with simple process is an urgent problem to be solved. Summary of the Invention

[0005] The present invention provides a method for preparing a polymer film / hydrogel composite material with a wrinkled surface. The method can be used to prepare a polymer film / hydrogel composite material with a wrinkled surface. The surface of the polymer film / hydrogel composite material with a wrinkled surface has a clear, regular, large-area wrinkled structure. The wrinkled structure is small and uniform, with a micron-level size. The preparation method is simple, does not rely on the application of external stress, and has broad application prospects.

[0006] The present invention also provides a polymer film / hydrogel composite material with a wrinkled surface, which is prepared by the above-mentioned preparation method of the polymer film / hydrogel composite material with a wrinkled surface. Therefore, the surface of the polymer film / hydrogel composite material with a wrinkled surface has an obvious, regular, large-area wrinkle structure. The wrinkle structure is small and uniform, with a micron-level size, and has potential application value in the fields of flexible electronics, biointerface engineering, and intelligent camouflage.

[0007] A first aspect of the present invention provides a method for preparing a polymer film / hydrogel composite material with a wrinkled surface, comprising: The hydrogel comprises a first surface and a second surface disposed opposite to each other. The first surface is adhered to a substrate, a polymer solution is coated on the second surface, and the polymer film / hydrogel composite material is obtained by sequentially performing a photocuring treatment and a drying treatment. placing the polymer film / hydrogel composite material in water at 5-32° C. for 1-60 minutes to obtain the polymer film / hydrogel composite material with wrinkled surface; The hydrogel is made from a raw material system including a water-soluble monomer containing a carbon-carbon double bond; the polymer solution is prepared by dispersing a polymer containing a carbon-carbon double bond in a solvent, and the polymer containing a carbon-carbon double bond is obtained by sequentially subjecting poly(styrene-butadiene-styrene) to an epoxidation reaction and acrylic acid modification.

[0008] The method for preparing the polymer film / hydrogel composite material with a wrinkled surface as described above, wherein the thickness of the polymer film in the polymer film / hydrogel composite material is 0.1-100 μm;

[0009] And / or, the mass percentage of the polymer containing carbon-carbon double bonds in the polymer solution is 1%-50%.

[0010] The method for preparing the surface wrinkled polymer film / hydrogel composite material as described above, wherein the water-soluble monomer containing carbon-carbon double bonds is at least one of acrylamide, acrylic acid, N-isopropylacrylamide, [3-(methacrylamido)propyl]trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, sodium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and 3-sulfopropyl acrylate;

[0011] And / or, the polymer containing carbon-carbon double bonds is poly(styrene-butadiene-styrene) containing carbon-carbon double bonds, and the chemical structure of the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is as follows:

[0012] ; Wherein, a, b, c, x, y, and a' are the mole fractions of the respective component units, satisfying: 0.1≤(a+a') / (a+a'+b+c+x+y)≤0.18, 0<(b+c) / (a+a'+b+c+x+y)<0.6, 0<x<0.4, 0<y<x, a+b+c+x+y+a'=1;

[0013] And / or, the solvent is at least one of dioxane, chloroform, toluene, acetone, ethanol, 1,4-dioxane, trifluorotoluene, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and deionized water.

[0014] The preparation method of the surface-wrinkled polymer film / hydrogel composite material as described above, wherein the hydrogel is made from a raw material system including a water-soluble monomer containing a carbon-carbon double bond, specifically comprises: dispersing the water-soluble monomer containing a carbon-carbon double bond, a crosslinking agent, and an initiator in water to obtain a prepolymer liquid; placing the prepolymer liquid in a mold and irradiating it under a 315-400nm ultraviolet lamp for 0.5-48 hours to obtain the hydrogel.

[0015] In the method for preparing the surface-wrinkled polymer film / hydrogel composite material as described above, in the prepolymer solution, the mass percentage of the water-soluble monomer containing carbon-carbon double bonds is 5%-90%, the mass percentage of the cross-linking agent is 0.01%-1%, and the mass percentage of the initiator is 0.1%-5%.

[0016] The method for preparing the surface wrinkled polymer film / hydrogel composite material as described above, wherein the conditions for the light curing treatment are: irradiation under a 315-400 nm ultraviolet lamp for 5-60 minutes;

[0017] And / or, during the drying process, the temperature is 30-80° C. and the time is 5-60 min.

[0018] In the method for preparing the polymer film / hydrogel composite material with a wrinkled surface as described above, the shape of the hydrogel includes any one of a cuboid, a cube, and a cylinder.

[0019] The method for preparing the polymer film / hydrogel composite material with a wrinkled surface as described above, wherein when the hydrogel is in the shape of a cuboid or a cube, the length of the hydrogel is 5-100 mm, the width is 5-100 mm, and the height is greater than 2 mm and less than 100 mm;

[0020] And / or, when the hydrogel is cylindrical, the diameter of the hydrogel is 5-100 mm, and the height is greater than 2 mm and less than 100 mm.

[0021] The second aspect of the present invention provides a polymer film / hydrogel composite material with a wrinkled surface, which is prepared by the preparation method of the polymer film / hydrogel composite material with a wrinkled surface.

[0022] The solution of the present invention has at least the following effects:

[0023] The present invention provides a method for preparing a surface-wrinkled polymer film / hydrogel composite material. The method combines the polymer film interface with the hydrogel interface through a free radical polymerization reaction to prevent delamination and extend the service life of the composite material. At the same time, the swelling difference between the first surface and the second surface of the hydrogel is utilized to cause the polymer network to diffuse in water to generate inward contraction stress, thereby causing the polymer film interface and the hydrogel interface to become unstable, inducing the generation of a wrinkled structure, and realizing the spontaneous formation and dynamic regulation of a micron-scale wrinkled structure, thereby avoiding the limitations of traditional methods that rely on external field stimulation or rigid materials. The surface of the surface-wrinkled polymer film / hydrogel composite material prepared by this method has a clear, regular, large-area wrinkled structure. The wrinkled structure is small and uniform, and is micron-sized. The method does not need to rely on the application of external stress, is simple to operate, and has broad application prospects. The present invention can achieve precise regulation of the wrinkle wavelength and amplitude of the polymer film / hydrogel composite material by controlling the raw materials, hydrogel thickness, immersion treatment time, etc., and can meet the needs of different application scenarios.

[0024] The surface-wrinkled polymer film / hydrogel composite material provided by the present invention has a distinct, regular, large-area wrinkle structure on its surface. The wrinkle structure is small and uniform, with a micron-scale size, and has potential application value in the fields of flexible electronics, biointerface engineering, and intelligent camouflage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 1H NMR spectra of poly(styrene-butadiene-styrene) (SBS), epoxidized SBS, and SBS containing double bonds in Example 1;

[0027] Figure 2 This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material with surface wrinkles in Example 1;

[0028] Figure 3This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material with surface wrinkles in Example 2;

[0029] Figure 4 This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material with surface wrinkles in Example 3;

[0030] Figure 5 This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material in Comparative Example 1;

[0031] Figure 6 This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material in Comparative Example 2;

[0032] Figure 7 This is an optical micrograph of the two-dimensional surface morphology of the hydrogel material in Comparative Example 3. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with embodiments of the present invention. Obviously, the described embodiments are part of embodiments of the present invention, rather than all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific techniques or conditions are not indicated in the embodiments, they are carried out according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments used that do not indicate manufacturers are conventional products that can be obtained commercially.

[0034] In the following description, the term "and / or" is used to describe the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, B exists alone, and A and B exist at the same time. A and B can be singular or plural.

[0035] The descriptions involving “first”, “second”, etc. in the present invention are used to distinguish similar objects, rather than to describe a specific order or sequence, and therefore should not be understood as limiting the present invention.

[0036] Those skilled in the art should understand that in the following description of the embodiments of the present invention, the order of serial numbers does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0037] It will be understood by those skilled in the art that the numerical ranges in the embodiments of the present invention are to be understood as also specifically disclosing each intermediate value between the upper and lower limits of the ranges. Each smaller range between any stated value or intermediate value within a stated range and any other stated value or intermediate value within the stated range is also encompassed within this application. The upper and lower limits of these smaller ranges may independently be included or excluded within the range.

[0038] Unless defined otherwise, technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0039] Constructing wrinkled structures on hydrogel surfaces allows precise control of properties such as wettability, adhesion, conductivity, and impact resistance, with important applications in flexible electronics, biointerface engineering, and intelligent camouflage. Swelling behavior, as an intrinsic property of hydrogels, provides a pathway for constructing wrinkled structures. However, conventional swelling processes are limited by the uniform expansion of the hydrogel network, often resulting in isotropic volume changes and making it difficult to form wrinkled structures.

[0040] Based on this, the first aspect of the present invention provides a method for preparing a polymer film / hydrogel composite material with a wrinkled surface, comprising: The hydrogel comprises a first surface and a second surface disposed opposite to each other. The first surface is adhered to a substrate, a polymer solution is coated on the second surface, and the polymer film / hydrogel composite material is obtained by sequentially performing a photocuring treatment and a drying treatment. placing the polymer film / hydrogel composite material in water at 5-32° C. for 1-60 minutes to obtain the polymer film / hydrogel composite material with wrinkled surface; The hydrogel is made of a raw material system including a water-soluble monomer containing a carbon-carbon double bond; the polymer solution is prepared by dispersing a polymer containing a carbon-carbon double bond in a solvent, and the polymer containing a carbon-carbon double bond is obtained by sequentially subjecting poly(styrene-butadiene-styrene) to an epoxidation reaction and acrylic acid modification.

[0041] The present invention does not particularly limit the specific manner of the above coating, and coating can be performed by methods well known in the art, such as drop coating, spin coating, scraping coating or spraying.

[0042] In the present invention, the substrate is a conventional substrate, for example, the substrate is an ordinary glass sheet, a gold sheet, a silver sheet, or the like.

[0043] The present invention does not limit the shape, size, and thickness of the substrate, which can be selected according to actual needs.

[0044] The present invention does not impose any particular limitation on the specific shape of the hydrogel. For example, the shape of the hydrogel may be a cuboid, a cube, or a cylinder.

[0045] In the present invention, the hydrogel has two oppositely disposed first and second surfaces.

[0046] When the hydrogel is in the shape of a cuboid or a cube, the hydrogel has six external surfaces, namely, an upper surface, a lower surface, a front surface, a rear surface, a left surface, and a right surface. In the present invention, the first surface can be used as the lower surface of the hydrogel, and the second surface can be used as the upper surface of the hydrogel.

[0047] When the hydrogel is cylindrical, the outer surface of the hydrogel has three surfaces, namely, an upper bottom surface, a lower bottom surface, and a side surface. In the present invention, the first surface can be used as the lower bottom surface of the hydrogel, and the second surface can be used as the upper bottom surface of the hydrogel.

[0048] In the present invention, the first surface is adhered to a substrate. This restricts the swelling of the hydrogel's first surface (maintaining firm contact with the substrate) while allowing the second surface to swell freely, resulting in a significant differential swelling between the first and second surfaces. This asymmetric swelling behavior induces inward contraction stress in the polymer network as it diffuses in water, leading to instability at the interface between the polymer film and the hydrogel, and inducing the formation of a wrinkled structure. Adhering the first surface to the substrate ensures the directional and stable generation of the wrinkled structure, avoiding stress dispersion caused by uniform swelling of the entire hydrogel, and providing a designable morphological foundation for the surface wrinkling.

[0049] The object prepared by the present invention is a polymer film / hydrogel composite material with a wrinkled surface. Specifically, the hydrogel includes a first surface and a second surface arranged opposite to each other. The first surface is adhered to a substrate, and a polymer solution is coated on the second surface to obtain a polymer film / hydrogel composite material precursor; the polymer film / hydrogel composite material precursor is first photocured, and then the product after the photocuring treatment is dried to obtain a polymer film / hydrogel composite material; the polymer film / hydrogel composite material is placed in water for immersion treatment to obtain a polymer film / hydrogel composite material with a wrinkled surface; the polymer film / hydrogel composite material with a wrinkled surface has a clear, regular, large-area wrinkled structure, and the wrinkled structure is small and uniform, with a micron-level size.

[0050] The hydrogel is made from a raw material system including water-soluble monomers containing carbon-carbon double bonds, and the polymer solution is prepared by dispersing a polymer containing carbon-carbon double bonds in a solvent. Therefore, both the hydrogel and the polymer solution contain carbon-carbon double bonds. During the photocuring process, the carbon-carbon double bonds in the hydrogel undergo free radical polymerization with those in the polymer solution, forming a stable covalent network structure. This enhances the mechanical strength of the polymer film and its interfacial bonding with the hydrogel, tightly bonding the polymer film interface to the hydrogel interface.

[0051] In the present invention, the above-mentioned drying treatment is to remove the solvent, shrink the polymer film and pre-store internal stress, thereby providing a driving force for asymmetric swelling (the first surface is restricted and the second surface is expanded) during the subsequent water immersion treatment, thereby directionally inducing interface instability and forming a controllable wrinkle structure.

[0052] The method for preparing a polymer film / hydrogel composite material with a wrinkled surface provided by the present invention realizes the precise control of the wrinkle wavelength and amplitude of the polymer film / hydrogel composite material, providing a new strategy for the application of multifunctional smart materials.

[0053] The principle of preparing the surface wrinkled polymer film / hydrogel composite material of the present invention is explained as follows:

[0054] The principle of the present invention is based on asymmetric swelling-induced interface instability: by firmly adhering the first surface of the hydrogel to the substrate to limit its swelling, while allowing the second surface of the hydrogel to swell freely, a significant swelling difference is formed between the first surface and the second surface. This asymmetric swelling behavior will induce the polymer network to diffuse in water to generate inward contraction stress, which in turn causes instability at the interface between the polymer film and the hydrogel, inducing the formation of a wrinkle structure. In the specific preparation process, a polymer solution is first coated on the second surface and photocured to enhance the mechanical strength of the polymer film and the interfacial bonding force with the hydrogel, and then the internal stress is pre-stored through a drying treatment; when immersed in water, the second surface of the hydrogel expands while the first surface is restricted, driving the polymer film interface and the hydrogel interface to undergo directional instability, forming a controllable wrinkle structure.

[0055] In a specific embodiment, during the above-mentioned soaking treatment, the temperature is 5-32° C. and the time is 1-60 min.

[0056] During the immersion treatment, the temperature and time parameters are each within the aforementioned ranges. The immersion temperature is controlled to be below the lower critical solution temperature of the hydrogel (e.g., poly(N-isopropylacrylamide)), maintaining the hydrogel's swollen state and preventing volume contraction due to temperature increases. This ensures continued free swelling of the hydrogel's second surface, thereby creating a stable swelling differential with the adhered first surface. This drives the polymer network to diffuse in the water, generating inward contraction stress, which in turn triggers instability at the interface between the polymer film and the hydrogel, ultimately inducing the formation of a wrinkled structure. Excessively high temperatures can cause the hydrogel to shrink, disrupting the asymmetric swelling conditions and unbalancing interfacial stresses, making it difficult to form a regular wrinkled structure.

[0057] For example, in the above-mentioned soaking treatment, the temperature may be any one of 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 32°C, or any two thereof;

[0058] The time may be any one of 1 min, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min, or a range consisting of any two of them.

[0059] In a specific embodiment, in the above-mentioned polymer film / hydrogel composite material, the thickness of the polymer film is 0.1-100 μm, for example, it can be any one of 0.1 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 57.2 μm, 60 μm, 70 μm, 75.2 μm, 80 μm, 90 μm, 100 μm or any two of them.

[0060] Furthermore, in the above polymer film / hydrogel composite material, the thickness of the polymer film may preferably be 50-100 μm.

[0061] In a specific embodiment, the mass percentage of the polymer containing carbon-carbon double bonds in the polymer solution is 1%-50%, preferably 10%-50%.

[0062] In a specific embodiment, the water-soluble monomer containing a carbon-carbon double bond is at least one of acrylamide, acrylic acid, N-isopropylacrylamide, [3-(methacrylamido)propyl]trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, sodium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and 3-sulfopropyl acrylate.

[0063] When the water-soluble monomers containing carbon-carbon double bonds are the aforementioned substances, their advantages lie in low-cost, readily available raw materials and excellent processing adaptability. These water-soluble monomers containing carbon-carbon double bonds have high solubility in water and can be directly prepared into prepolymer solutions without the need for organic solvents, which reduces production costs and meets environmental requirements. Their carbon-carbon double bonds are highly reactive and can be efficiently polymerized by light or heat, forming a hydrophilic network structure that imparts high swelling properties, biocompatibility, and adjustable mechanical properties to the hydrogel. Furthermore, the molecular structure of these water-soluble monomers containing carbon-carbon double bonds is easily modified, facilitating further functionalization and achieving a comprehensive balance between cost-effectiveness, practicality, and performance designability.

[0064] In a specific embodiment, the polymer containing carbon-carbon double bonds is poly(styrene-butadiene-styrene) containing carbon-carbon double bonds, and the chemical structure of the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is as follows:

[0065] ; Wherein, a, b, c, x, y, and a' are the mole fractions of the component units, satisfying: 0.1≤(a+a') / (a+a'+b+c+x+y)≤0.18, 0<(b+c) / (a+a'+b+c+x+y)<0.6, 0<x<0.4, 0<y<x, a+b+c+x+y+a'=1.

[0066] In the present invention, the carbon-carbon double bond in the poly(styrene-butadiene-styrene) containing a carbon-carbon double bond specifically refers to the carbon-carbon double bond on the acrylic acid group thereof.

[0067] When the polymer containing carbon-carbon double bonds is the above-mentioned substance, cross-linking is initiated by light or heating, and the carbon-carbon double bonds in the polymer solution undergo free radical polymerization reaction with the carbon-carbon double bonds in the hydrogel to form covalent connections, significantly improving the interfacial adhesion and avoiding stratification.

[0068] In a specific embodiment, the solvent is at least one of dioxane, chloroform, toluene, acetone, ethanol, 1,4-dioxane, trifluorotoluene, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and deionized water.

[0069] In one specific embodiment, the hydrogel is prepared from a raw material system including a water-soluble monomer containing a carbon-carbon double bond, specifically comprising: dispersing a water-soluble monomer containing a carbon-carbon double bond, a crosslinking agent, and an initiator in water to obtain a prepolymer solution; placing the prepolymer solution in a mold and irradiating it under a 315-400nm ultraviolet lamp for 0.5-48 hours to obtain the hydrogel.

[0070] The present invention does not impose any particular limitation on the specific material of the mold, which may be a conventional material. For example, the mold may be made of polytetrafluoroethylene.

[0071] In one specific embodiment, in the prepolymer solution, the weight percentage of the water-soluble monomer containing a carbon-carbon double bond is 5%-90%, the weight percentage of the cross-linking agent is 0.01%-1%, and the weight percentage of the initiator is 0.1%-5%. Furthermore, in the prepolymer solution, the weight percentage of the water-soluble monomer containing a carbon-carbon double bond is preferably 40%-90%, the weight percentage of the cross-linking agent is preferably 0.2%-1%, and the weight percentage of the initiator is preferably 1%-5%.

[0072] When the mass percentage of the water-soluble monomer containing carbon-carbon double bonds, the mass percentage of the cross-linking agent, and the mass percentage of the initiator in the prepolymer liquid are each within the above ranges, while ensuring efficient cross-linking and curing, the brittleness caused by excessive cross-linking or the side reactions caused by excessive initiator are reduced.

[0073] In a specific embodiment, the photocuring treatment is performed under a 315-400 nm ultraviolet lamp for 5-60 min. Furthermore, the photocuring treatment is preferably performed under a 365 nm ultraviolet lamp for 5-30 min.

[0074] In a specific embodiment, during the drying process, the temperature is 30-80° C. and the time is 5-60 min.

[0075] For example, in the drying process, the temperature may be any one of 30°C, 40°C, 50°C, 60°C, 70°C, and 80°C, or any two thereof;

[0076] The time may be any one of 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, or a range consisting of any two of them.

[0077] The present invention does not particularly limit the specific shape of the hydrogel. In one embodiment, the shape of the hydrogel includes any one of a cuboid, a cube, and a cylinder.

[0078] In a specific embodiment, when the shape of the hydrogel is a cuboid or a cube, the length of the hydrogel is 5-100 mm, the width is 5-100 mm, and the height is greater than 2 mm and less than 100 mm.

[0079] In a specific embodiment, when the hydrogel is in the shape of a cylinder, the diameter of the hydrogel is 5-100 mm, and the height is greater than 2 mm and less than 100 mm.

[0080] If the hydrogel height is less than or equal to 2 mm, it is difficult to form a clear, large-scale wrinkle structure. This may be because the insufficient thickness of the hydrogel leads to insufficient accumulation of swelling differences between the first and second surfaces, making it difficult to generate sufficient shrinkage stress and drive interface instability, resulting in the lack of clear, large-scale wrinkle structure. If the hydrogel height exceeds 100 mm, the reduced water diffusion efficiency and gravity will affect the uniformity of the swelling rate, which may lead to disordered distribution of wrinkles or local collapse. Therefore, controlling the height to greater than 2 mm and less than 100 mm can ensure effective stress accumulation due to asymmetric swelling while maintaining a balance between solvent diffusion dynamics and interface instability, thereby obtaining an orientation-controlled wrinkle structure.

[0081] The present invention does not particularly limit the type of the crosslinking agent used, and conventional types in the art can be used. Preferably, the crosslinking agent can be at least one of N,N-methylenebisacrylamide, polyethylene glycol diacrylate, and polyethylene glycol diglycidyl ether.

[0082] The present invention does not particularly limit the type of the specific initiator used, and conventional types in the art can be used. Preferably, the initiator can be at least one of ammonium persulfate, potassium persulfate, azobisisobutyronitrile, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, and α-ketoglutaric acid.

[0083] In some embodiments, the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is obtained by a preparation method comprising the following steps:

[0084] 5 g of poly(styrene-butadiene-styrene), 0.565 mL of formic acid, 0.05 mL of polyethylene glycol-600, and 50 mL of toluene were mixed and subjected to a first stirring treatment to obtain a product; 1.5 mL of hydrogen peroxide was added to the product and subjected to a second stirring treatment to obtain epoxidized poly(styrene-butadiene-styrene);

[0085] A mixture of 3.8 mL of acrylic acid and 0.0169 g of hydroquinone and 3.5 g of epoxidized poly(styrene-butadiene-styrene) were added to 35 mL of toluene for a third stirring treatment to obtain poly(styrene-butadiene-styrene) containing carbon-carbon double bonds.

[0086] The present invention modifies poly(styrene-butadiene-styrene) through the above process to prepare poly(styrene-butadiene-styrene) containing carbon-carbon double bonds, and the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds can be used to prepare the above polymer solution.

[0087] In some embodiments, during the first stirring treatment, the temperature is 68-72° C. and the time is 1.5-3 h.

[0088] In some embodiments, during the second stirring treatment, the temperature is 68-72° C. and the time is 1.5-3 h.

[0089] In some embodiments, the third stirring treatment is performed at a temperature of 70-80° C. for 15-25 hours.

[0090] A second aspect of the present invention provides a wrinkled polymer film / hydrogel composite material, produced using the aforementioned method. This wrinkled polymer film / hydrogel composite material exhibits environmentally responsive properties, and its surface wrinkles are micron-sized, showing potential applications in flexible electronics, biointerface engineering, and intelligent camouflage.

[0091] The present invention is further described below through specific examples.

[0092] Example 1

[0093] This embodiment provides a method for preparing a polymer film / hydrogel composite material with a wrinkled surface, comprising:

[0094] (1) Preparation of poly(styrene-butadiene-styrene) (SBS) containing carbon-carbon double bonds

[0095] 5 g of poly(styrene-butadiene-styrene) (0.0375 mmol) was dispersed in 50 mL of toluene, and then 0.565 mL of formic acid (0.0132 mol) and 0.05 mL of polyethylene glycol-600 (0.083 mol) were added. The mixture was stirred at 70° C. for 2 h using a magnetic stirrer. 1.5 mL of hydrogen peroxide was then added, and stirring was continued at 70° C. for 2 h. After cooling, the mixture was precipitated with anhydrous ethanol to obtain a first solid. The first solid was then washed with deionized water to obtain a clean first solid. The clean first solid was dried in a vacuum oven at 35° C. overnight to obtain epoxidized poly(styrene-butadiene-styrene) (denoted as epoxidized SBS).

[0096] 3.5 g of epoxidized SBS (0.0257 mmol) was dispersed in 35 mL of toluene, and then a mixture of 3.8 mL of acrylic acid (0.0548 mol) and 0.0169 g of hydroquinone (0.153 mol) was added. The mixture was heated to 75° C. and stirred at 75° C. for 20 h using a magnetic stirrer. After cooling, the mixture was precipitated with anhydrous ethanol to obtain a second solid. The second solid was then washed with deionized water to obtain a clean second solid. The clean second solid was dried in a vacuum oven at 35° C. overnight to obtain poly(styrene-butadiene-styrene) containing carbon-carbon double bonds (denoted as SBS containing double bonds).

[0097] (2) Preparation of surface wrinkled polymer film / hydrogel composites

[0098] 2 g of acrylamide, 0.01 g of N,N-methylenebisacrylamide, and 0.05 g of α-ketoglutaric acid were dissolved in 5 g of water and stirred thoroughly for 30 minutes to obtain a prepolymer solution. The prepolymer solution was then injected into a polytetrafluoroethylene mold with a rectangular cavity structure having a closed bottom and surrounding area and an open top. The polytetrafluoroethylene mold was sealed and exposed to a 365 nm ultraviolet lamp for 2 hours. The product after illumination was removed from the mold to obtain a hydrogel with a length of 10 mm, a width of 10 mm, and a height of 4 mm.

[0099] Disperse 1 g of SBS containing double bonds in 10 mL of toluene, stir thoroughly for 6 h, and filter with a filter to obtain a polymer solution;

[0100] The lower surface of the hydrogel was adhered to a common glass slide, and then 0.1 mL of the polymer solution was spin-coated on the upper surface of the hydrogel using a spin coater at a rotation speed of 2000 rpm. The hydrogel was then exposed to a 365 nm ultraviolet lamp for 5 minutes and then dried in an oven at 40°C for 30 minutes to obtain a polymer film / hydrogel composite material. The polymer film in the polymer film / hydrogel composite material had a thickness of 57.2 μm.

[0101] The polymer film / hydrogel composite material was immersed in water at 25° C. for 30 minutes to obtain a polymer film / hydrogel composite material with wrinkled surface.

[0102] Example 2

[0103] The preparation method of the surface wrinkled polymer film / hydrogel composite material provided in this embodiment is basically the same as that in Example 1, except that:

[0104] The hydrogel was a cuboid with a length of 10 mm, a width of 10 mm, and a height of 10 mm.

[0105] Example 3

[0106] The preparation method of the surface wrinkled polymer film / hydrogel composite material provided in this embodiment is basically the same as that in Example 1, except that:

[0107] The prepolymer solution was prepared by dissolving 2 g of N-isopropylacrylamide, 0.01 g of N,N-methylenebisacrylamide and 0.05 g of α-ketoglutaric acid in 5 g of water and stirring thoroughly for 30 minutes.

[0108] Comparative Example 1

[0109] The preparation method of the polymer film / hydrogel composite material provided in this comparative example is basically the same as that in Example 1, except that:

[0110] The hydrogel was a cuboid with a length of 10 mm, a width of 10 mm, and a height of 2 mm.

[0111] Comparative Example 2

[0112] The preparation method of the rough surface polymer film / hydrogel composite material provided in this comparative example is basically the same as that in Example 1, except that:

[0113] The temperature during the immersion treatment is 50° C. Specifically, the polymer film / hydrogel composite material is immersed in 50° C. water for 30 minutes to obtain a polymer film / hydrogel composite material with a rough surface.

[0114] Comparative Example 3

[0115] This comparative example provides a method for preparing a hydrogel material, comprising the following steps:

[0116] 2 g of acrylamide, 0.01 g of N,N-methylenebisacrylamide, and 0.05 g of α-ketoglutaric acid were dissolved in 5 g of water and stirred thoroughly for 30 minutes to obtain a prepolymer solution. The prepolymer solution was injected into a mold with a rectangular cavity structure having a closed lower end and surrounding areas and an open upper end. The mold was sealed and irradiated under a 365 nm ultraviolet lamp for 2 hours. The illuminated product was removed from the mold to obtain a hydrogel. The hydrogel was immersed in 25° C. water for 30 minutes to obtain a hydrogel material.

[0117] Performance Testing

[0118] 1. The poly(styrene-butadiene-styrene) (SBS), epoxidized SBS and SBS containing double bonds in Example 1 of the present invention were subjected to H NMR spectrum test. The structures are as follows: Figure 1 As shown; Figure 1 The H-NMR spectra of SBS, epoxidized SBS and SBS containing double bonds in the present invention are shown in FIG.

[0119] Depend on Figure 1 It can be seen that compared with SBS, two new signal peaks appeared at 2.71 and 2.95 ppm in the green part of the NMR hydrogen spectrum, corresponding to the chemical shifts of the cis-epoxy group and the trans-epoxy group, indicating the successful introduction of the epoxy group, that is, the successful preparation of epoxidized SBS; after the introduction of the acrylic acid ring-opening reaction, the signal peaks at 2.71 and 2.95 ppm weakened, while the blue part showed new characteristic signal peaks of acrylic acid groups at 5.87 and 6.15 ppm, indicating the successful introduction of the carbon-carbon double bond, that is, the successful preparation of double-bond SBS. The chemical structure of double-bond SBS is as follows: ; Wherein, a, b, c, x, y, and a' are the mole fractions of each component unit, (a+a') / (a+a'+b+c+x+y)=0.12, (b+c) / (a+a'+b+c+x+y)=0.51, x=0.25, y=0.12, a+b+c+x+y+a'=1, which are calculated based on H NMR spectrum.

[0120] 2. The surface morphology of the polymer film / hydrogel composite materials with wrinkled surfaces in Examples 1-3 of the present invention, the polymer film / hydrogel composite material in Comparative Example 1, the polymer film / hydrogel composite material with rough surface in Comparative Example 2, and the hydrogel material in Comparative Example 3 were tested using a LEXT OLS5000 confocal microscope. The results are as follows: Figure 2-7 As shown, the surface morphology test results of the polymer film / hydrogel composite materials with wrinkled surfaces in Examples 1-3 and the polymer film / hydrogel composite materials with rough surfaces in Comparative Example 2 were then imported into the software Analysis application to scan the wrinkle wavelength and amplitude to obtain the corresponding values ​​(see Table 1); Figure 2 This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material with surface wrinkles in Example 1; Figure 3 This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material with surface wrinkles in Example 2; Figure 4 This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material with surface wrinkles in Example 3; Figure 5 This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material in Comparative Example 1; Figure 6 This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material in Comparative Example 2; Figure 7 This is an optical micrograph of the two-dimensional surface morphology of the hydrogel material in Comparative Example 3.

[0121] Table 1 Test results project Wrinkle wavelength (μm) Wrinkle amplitude (μm) Example 1 41.9 17.7 Example 2 24.2 9.2 Example 3 13.5 5.9 Comparative Example 2 423.5 53.9

[0122] Depend on Figure 2-4As shown in Table 1, the surface wrinkled polymer film / hydrogel composites of Examples 1-3 exhibited distinct, regular, and large-area wrinkle structures, and these wrinkles were fine and uniform. The wrinkle wavelength of the surface wrinkled polymer film / hydrogel composite in Example 1 was 41.9 μm and the amplitude was 17.7 μm; the wrinkle wavelength of the surface wrinkled polymer film / hydrogel composite in Example 2 was 24.2 μm and the amplitude was 9.2 μm; and the wrinkle wavelength of the surface wrinkled polymer film / hydrogel composite in Example 3 was 13.5 μm and the amplitude was 5.9 μm. These results indicate that the wrinkle wavelength and amplitude are related to the thickness of the hydrogel and the water-soluble monomer containing carbon-carbon double bonds. Therefore, the surface wrinkle morphology of the polymer film / hydrogel composite can be adjusted by controlling the hydrogel thickness or using different water-soluble monomers containing carbon-carbon double bonds. Furthermore, these results demonstrate that the surface wrinkle structures of the surface wrinkled polymer film / hydrogel composite are micrometer-sized.

[0123] Depend on Figure 5 As can be seen, the polymer film / hydrogel composite material in Comparative Example 1 lacks obvious, large-scale wrinkles. This is likely due to the insufficient thickness of the hydrogel, resulting in insufficient swelling differences between the upper and lower surfaces, making it difficult to induce surface buckling. Therefore, no obvious, large-scale wrinkles were observed on the polymer film / hydrogel composite material in Comparative Example 1. Therefore, scans of wrinkle wavelength and amplitude were not performed.

[0124] Depend on Figure 6 Combined with Table 1, it can be seen that the wrinkle structure of the surface of the rough-surfaced polymer film / hydrogel composite material in Comparative Example 2 is rough, uneven and irregular, with a wrinkle wavelength of 423.5 μm and an amplitude of 53.9 μm, indicating that the wrinkle wavelength and amplitude of the rough-surfaced polymer film / hydrogel composite material in Comparative Example 2 are large. The reason may be that when the temperature during the immersion treatment is 50°C, it exceeds the lower critical solution temperature of poly(N-isopropylacrylamide), and some hydrogen bonds in the hydrogel network are destroyed, and the solvation layer of the hydrophobic part of the macromolecular chain is subsequently destroyed. The hydrogel network changes from a loose coil structure to a tight colloid structure, inducing the volume to shrink again, destroying the surface wrinkle structure, thereby showing a rough, uneven and irregular wrinkle structure.

[0125] from Figure 7 It can be seen that no wrinkle structure appeared on the surface of the hydrogel material in Comparative Example 3, indicating that the hydrogel in Comparative Example 3 could not produce a wrinkle structure when swelled in water. Since no wrinkle structure appeared on the surface of the hydrogel material in Comparative Example 3, the wrinkle wavelength and amplitude were not scanned.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a polymer film / hydrogel composite material with a wrinkled surface, characterized in that: include: The hydrogel comprises a first surface and a second surface disposed opposite to each other. The first surface is adhered to a substrate, a polymer solution is coated on the second surface, and the polymer film / hydrogel composite material is obtained by sequentially performing a photocuring treatment and a drying treatment. placing the polymer film / hydrogel composite material in water at 5-32° C. for 1-60 minutes to obtain the polymer film / hydrogel composite material with wrinkled surface; The hydrogel is made from a raw material system including a water-soluble monomer containing a carbon-carbon double bond; the polymer solution is prepared by dispersing a polymer containing a carbon-carbon double bond in a solvent, and the polymer containing a carbon-carbon double bond is obtained by sequentially subjecting poly(styrene-butadiene-styrene) to an epoxidation reaction and acrylic acid modification.

2. The method for preparing a polymer film / hydrogel composite material with a wrinkled surface according to claim 1, characterized in that: In the polymer film / hydrogel composite material, the thickness of the polymer film is 0.1-100 μm; And / or, the mass percentage of the polymer containing carbon-carbon double bonds in the polymer solution is 1%-50%.

3. The method for preparing a polymer film / hydrogel composite material with a wrinkled surface according to claim 1, characterized in that: The water-soluble monomer containing a carbon-carbon double bond is at least one of acrylamide, acrylic acid, N-isopropylacrylamide, [3-(methacrylamido)propyl]trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, sodium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and 3-sulfopropylacrylate; And / or, the polymer containing carbon-carbon double bonds is poly(styrene-butadiene-styrene) containing carbon-carbon double bonds, and the chemical structure of the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is as follows: ； Wherein, a, b, c, x, y, and a' are the mole fractions of the respective component units, satisfying: 0.1≤(a+a') / (a+a'+b+c+x+y)≤0.18, 0<(b+c) / (a+a'+b+c+x+y)<0.6, 0<x<0.4, 0<y<x, a+b+c+x+y+a'=1; And / or, the solvent is at least one of dioxane, chloroform, toluene, acetone, ethanol, 1,4-dioxane, trifluorotoluene, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and deionized water.

4. The method for preparing a polymer film / hydrogel composite material with a wrinkled surface according to claim 1, characterized in that: The hydrogel is made from a raw material system including a water-soluble monomer containing a carbon-carbon double bond, specifically comprising: dispersing a water-soluble monomer containing a carbon-carbon double bond, a crosslinking agent, and an initiator in water to obtain a prepolymer solution; placing the prepolymer solution in a mold and irradiating it under a 315-400nm ultraviolet lamp for 0.5-48 hours to obtain the hydrogel.

5. The method for preparing a polymer film / hydrogel composite material with a wrinkled surface according to claim 4, characterized in that: In the prepolymer solution, the mass percentage of the water-soluble monomer containing carbon-carbon double bonds is 5%-90%, the mass percentage of the cross-linking agent is 0.01%-1%, and the mass percentage of the initiator is 0.1%-5%.

6. The method for preparing a polymer film / hydrogel composite material with a wrinkled surface according to claim 1, characterized in that: The conditions of the light curing treatment are: irradiation under a 315-400nm ultraviolet lamp for 5-60 minutes; And / or, during the drying process, the temperature is 30-80° C. and the time is 5-60 min.

7. The method for preparing a polymer film / hydrogel composite material with a wrinkled surface according to claim 1, characterized in that: The shape of the hydrogel includes any one of a cuboid, a cube, and a cylinder.

8. The method for preparing a polymer film / hydrogel composite material with a wrinkled surface according to claim 7, characterized in that: When the shape of the hydrogel is a cuboid or a cube, the length of the hydrogel is 5-100 mm, the width is 5-100 mm, and the height is greater than 2 mm and less than 100 mm; And / or, when the hydrogel is cylindrical, the diameter of the hydrogel is 5-100 mm, and the height is greater than 2 mm and less than 100 mm.

9. A polymer film / hydrogel composite material with a wrinkled surface, characterized in that: The composite material is prepared by the method for preparing the polymer film / hydrogel composite material with wrinkled surface according to any one of claims 1 to 8.

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