A method for preparing a surface-ridged polymer film / hydrogel composite

Abstract

The present application relates to the technical field of composite material preparation, and particularly relates to a preparation method of a surface-wrinkled polymer film / hydrogel composite material. The preparation method of the surface-wrinkled polymer film / hydrogel composite material comprises the following steps: a hydrogel comprises a first surface and a second surface arranged oppositely, the first surface is adhered to a substrate, a polymer solution is coated on the second surface, and then a photo-curing treatment and a drying treatment are sequentially performed to obtain a polymer film / hydrogel composite material; and the polymer film / hydrogel composite material is placed in water for immersion treatment, and the surface-wrinkled polymer film / hydrogel composite material is obtained. The wavelength and amplitude of the wrinkles of the polymer film / hydrogel composite material can be accurately controlled by controlling the raw materials, the thickness of the hydrogel and the immersion treatment time, and the requirements of different application scenarios can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material preparation, and particularly relates to a preparation method of a surface-wrinkled polymer film / hydrogel composite material. BACKGROUND

[0002] Hydrogel is a kind of three-dimensional soft material composed of a hydrophilic polymer network. Due to its high water content, adjustable mechanical properties and excellent biocompatibility, it has great application potential in the fields of biomedical, flexible sensing, microfluidic chip, optical regulation and information encryption. Studies have shown that the construction of wrinkle structure on the surface of hydrogel can precisely regulate its wettability, adhesion, conductivity and impact resistance, and has important application value in the fields of flexible electronics, biological interface engineering and intelligent camouflage.

[0003] At present, the construction of wrinkle structure on the surface of hydrogel usually depends on mechanical pre-stretching or interfacial modulus mismatch, but these methods often require complex external field regulation or strict preparation conditions, which limits the programmability and environmental adaptability of the material. For example, the Chinese patent application with the publication number CN118530494A discloses a surface-wrinkled core-shell structure polymer particle and its preparation method and application. The dry water-absorbing resin beads are fully absorbed and expanded, then placed in a carbon source aqueous solution, soaked and adsorbed a layer of film, and then dehydrated and shrunk to a dry state to obtain a surface-wrinkled core-shell structure polymer particle. The patent application is only suitable for a specific core-shell system, and it is difficult to realize dynamic regulation of micron-scale wrinkle morphology. The Chinese patent application with the publication number CN110105593A discloses a preparation method of a surface-wrinkled alginate / polyacrylamide composite hydrogel. The calcium ion cross-linked alginate / polyacrylamide hydrogel is pre-stretched, and then soaked in a ferric chloride aqueous solution to prepare a surface-wrinkled composite hydrogel. The patent application needs to rely on the application of external stress, and the control requirements of the pre-stretching force and direction are high, and the operation is complex.

[0004] Therefore, it is an urgent problem to develop a new method for constructing the wrinkle structure on the surface of hydrogel with simple process. SUMMARY

[0005] The present application provides a preparation method of a surface-wrinkled polymer film / hydrogel composite material. The surface-wrinkled polymer film / hydrogel composite material can be prepared by the method. The surface of the surface-wrinkled polymer film / hydrogel composite material has obvious, regular and large-area wrinkle structure. The wrinkle structure is small and uniform, and is micron-sized. The preparation method is simple, does not need to rely on the application of external stress, and has wide application prospect.

[0006] The application further provides a surface-creped polymer film / hydrogel composite material prepared by the above method, and the surface of the surface-creped polymer film / hydrogel composite material has obvious, regular and large-area creped structures, the creped structures are micron-sized and uniform, and the surface-creped polymer film / hydrogel composite material has potential application value in the fields of flexible electronics, biological interface engineering and intelligent camouflage.

[0007] The first aspect of the application provides a method for preparing a surface-creped polymer film / hydrogel composite material, comprising the following steps:

[0008] The hydrogel comprises a first surface and a second surface arranged oppositely, the first surface is adhered to a substrate, and a polymer solution is coated on the second surface, and then subjected to a photo-curing treatment and a drying treatment to obtain a polymer film / hydrogel composite material;

[0009] The polymer film / hydrogel composite material is immersed in water at 5-32 DEG C for 1-60 min to obtain the surface-creped polymer film / hydrogel composite material;

[0010] The hydrogel is prepared from a raw material system comprising 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 an acrylic acid modification.

[0011] The method for preparing a surface-creped polymer film / hydrogel composite material as described above, wherein the thickness of the polymer film in the polymer film / hydrogel composite material is 0.1-100 μm;

[0012] The mass percentage of the polymer containing a carbon-carbon double bond in the polymer solution is 1%-50%.

[0013] The method for preparing a surface-creped polymer film / hydrogel composite material as described above, wherein the water-soluble monomer containing a carbon-carbon double bond is at least one of acrylamide, acrylic acid, N-isopropyl acrylamide, [3-(methacryloylamino)propyl]trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, sodium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid and 3-sulfopropyl acrylate.

[0014] The polymer containing a carbon-carbon double bond is a poly(styrene-butadiene-styrene) containing a carbon-carbon double bond, and the chemical structural formula of the poly(styrene-butadiene-styrene) containing a carbon-carbon double bond is as follows:

[0015] ;

[0016] 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;

[0017] 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.

[0018] 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.

[0019] 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%.

[0020] 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;

[0021] And / or, during the drying process, the temperature is 30-80° C. and the time is 5-60 min.

[0022] 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.

[0023] 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;

[0024] 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.

[0025] The second aspect of the present application provides a surface-creped polymer film / hydrogel composite material prepared by the method for preparing a surface-creped polymer film / hydrogel composite material.

[0026] The scheme of the present application has at least the following effects:

[0027] The method for preparing a surface-creped polymer film / hydrogel composite material provided by the present application combines the polymer film interface and the hydrogel interface together through a free radical polymerization reaction, prevents delamination, and prolongs the service life of the composite material. Meanwhile, the swelling difference between the first surface and the second surface of the hydrogel causes the polymer network to diffuse in water to generate an inward shrinkage stress, which further induces the instability of the polymer film interface and the hydrogel interface, and induces the generation of a creped structure, thereby realizing the spontaneous formation and dynamic regulation of a micron-level creped structure and avoiding the limitations of traditional methods that rely on external field stimulation or rigid materials. The surface-creped polymer film / hydrogel composite material prepared by the method has a clear, regular, and large-area creped structure, and the creped structure is small and uniform, with a micron-level size. The method does not need to rely on the application of external stress, is simple to operate, and has a wide application prospect. The present application can realize the accurate regulation of the creped wavelength and amplitude of the polymer film / hydrogel composite material by controlling the raw materials, the thickness of the hydrogel, and the soaking treatment time, and can meet the needs of different application scenarios.

[0028] The surface-creped polymer film / hydrogel composite material provided by the present application has a clear, regular, and large-area creped structure on the surface, and the creped structure is small and uniform, with a micron-level size, and has potential application value in the fields of flexible electronics, biological interface engineering, and intelligent camouflage. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1 NMR hydrogen spectrum of poly(styrene-butadiene-styrene) (SBS), epoxidized SBS, and SBS containing double bonds in Example 1;

[0031] Figure 2 Optical micrograph of the two-dimensional surface creped morphology of the surface-creped polymer film / hydrogel composite material in Example 1;

[0032] Figure 3Optical micrograph of two-dimensional surface wrinkle topography of the surface-wrinkled polymer film / hydrogel composite material in Example 2;

[0033] Figure 4 Optical micrograph of two-dimensional surface wrinkle topography of the surface-wrinkled polymer film / hydrogel composite material in Example 3;

[0034] Figure 5 Optical micrograph of two-dimensional surface wrinkle topography of the polymer film / hydrogel composite material in Comparative Example 1;

[0035] Figure 6 Optical micrograph of two-dimensional surface wrinkle topography of the polymer film / hydrogel composite material in Comparative Example 2;

[0036] Figure 7 Optical micrograph of two-dimensional surface topography of the hydrogel material in Comparative Example 3. DETAILED DESCRIPTION

[0037] In order to make the objects, technical solutions and advantages of the present application clearer, the following will combine the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application. If the specific technology or condition is not indicated in the embodiments, the technology or condition described in the literature in the art or according to the product instruction is adopted. If the reagent or instrument is not indicated by the manufacturer, it is a conventional product that can be obtained by market purchase.

[0038] In the following description, the term "and / or" is used to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the following three cases: A exists alone, B exists alone and A and B exist simultaneously. Wherein A and B can be singular or plural.

[0039] In the present application, the description of "first", "second" and the like is used to distinguish similar objects, and is not used to describe a specific sequence or chronological order, and therefore should not be understood as a limitation on the present application.

[0040] Those skilled in the art should understand that in the following description of the embodiments of the present application, the sequence of the serial numbers does not mean the sequence of the execution, and part or all of the steps can be executed in parallel or in sequence, and the execution sequence of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0041] Those skilled in the art will understand that the numerical ranges in the embodiments of the present application should be understood to also specifically disclose each intermediate value between the upper and lower limits of the range. Each intermediate value within any stated value or stated range, as well as any other stated value or intermediate value within the stated range, is also encompassed within the present application. The upper and lower limits of these smaller ranges can be independently included or excluded from the ranges.

[0042] Unless otherwise defined, technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0043] The construction of wrinkle structure on the surface of hydrogel can precisely regulate its wettability, adhesion, conductivity and impact resistance, etc., and has important application value in the fields of flexible electronics, biological interface engineering and intelligent camouflage, etc. Swelling behavior, as an intrinsic property of hydrogel, provides a way for the construction of wrinkle structure. However, the traditional swelling process is limited by the uniform expansion of hydrogel network, which often leads to isotropic volume change and is difficult to form wrinkle structure.

[0044] Based on this, the first aspect of the present application provides a preparation method of a surface-wrinkled polymer film / hydrogel composite material, comprising:

[0045] The hydrogel comprises a first surface and a second surface arranged oppositely, the first surface is adhered to a substrate, and a polymer solution is coated on the second surface, and then subjected to light curing treatment and drying treatment in sequence to obtain a polymer film / hydrogel composite material;

[0046] The polymer film / hydrogel composite material is immersed in water at 5-32 DEG C for 1-60 min to obtain the surface-wrinkled polymer film / hydrogel composite material;

[0047] The hydrogel is made of a raw material system comprising 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 epoxidation reaction and acrylic acid modification.

[0048] The present application does not particularly limit the specific method of coating, and the coating can be carried out by methods well known in the art, such as drop coating, spin coating, blade coating or spraying, etc.

[0049] In the present application, the above-mentioned substrate is a conventional substrate, for example, the substrate is a common glass sheet, a gold sheet or a silver sheet, etc.

[0050] The present application does not limit the shape, size and thickness of the substrate, which can be selected according to actual needs.

[0051] The present application does not particularly limit the specific shape of the hydrogel, for example, the shape of the hydrogel can be a cuboid, a cube or a cylinder.

[0052] In the present application, the hydrogel has two oppositely arranged first and second surfaces.

[0053] When the shape of the hydrogel is a cuboid or a cube, the outer surface of the hydrogel has a total of six surfaces, which are the upper surface, the lower surface, the front side surface, the rear side surface, the left side surface and the right side surface. In the present application, 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.

[0054] When the shape of the hydrogel is a cylinder, the outer surface of the hydrogel has a total of three surfaces, which are the upper bottom surface, the lower bottom surface and the side surface. In the present application, 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.

[0055] In the present application, the first surface is adhered to the substrate, and by limiting the swelling of the first surface of the hydrogel (the first surface is firmly in contact with the substrate), while allowing the second surface of the hydrogel to swell freely, a significant swelling difference is formed between the first and second surfaces. This asymmetric swelling behavior induces the polymer network to diffuse in water to generate an inward shrinkage stress, which in turn triggers the instability of the polymer film interface and the hydrogel interface, inducing the generation of a wrinkled structure. In the present application, the first surface is adhered to the substrate to ensure the directional generation and stable control of the wrinkled structure, and to avoid the dispersion of stress caused by the uniform swelling of the whole hydrogel, thereby providing a designable morphology basis for the surface wrinkled structure.

[0056] The present application is a polymer film / hydrogel composite material with a wrinkled surface, specifically, the hydrogel includes oppositely arranged first and second surfaces, the first surface is adhered to the 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 subjected to a photocuring treatment, and then the product after the photocuring treatment is subjected to a drying treatment to obtain a polymer film / hydrogel composite material; the polymer film / hydrogel composite material is immersed in water for soaking treatment, thereby obtaining a polymer film / hydrogel composite material with a wrinkled surface; the polymer film / hydrogel composite material with a wrinkled surface has a clear, regular and large-area wrinkled structure, and the wrinkled structure is small and uniform, with a micron-level size.

[0057] The hydrogel is made of a raw material system containing water-soluble monomers with carbon-carbon double bonds, and the polymer solution is made by dispersing the polymer with carbon-carbon double bonds in a solvent. Therefore, the hydrogel and the polymer solution both contain carbon-carbon double bonds. During the photocuring process, the carbon-carbon double bonds in the hydrogel and the carbon-carbon double bonds in the polymer solution undergo radical polymerization to form a stable covalent network structure, thereby enhancing the mechanical strength of the polymer film and the interfacial adhesion between the polymer film and the hydrogel, and tightly bonding the polymer film interface and the hydrogel interface together.

[0058] In the present application, the drying process is to remove the solvent, shrink the polymer film and pre-store internal stress, so as to provide driving force for the subsequent asymmetric swelling (the first surface is limited and the second surface is expanded) of the water immersion process, thereby directionally inducing the interface instability and forming a controllable wrinkle structure.

[0059] The preparation method of the surface-wrinkled polymer film / hydrogel composite material provided by the present application realizes the accurate control of the wrinkle wavelength and amplitude of the polymer film / hydrogel composite material, and provides a new strategy for the application of multifunctional smart materials.

[0060] The principle of preparing the surface-wrinkled polymer film / hydrogel composite material of the present application is described as follows:

[0061] The principle of the present application is based on the 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 induces the polymer network to diffuse in water to generate inward shrinkage stress, which in turn triggers the instability of the polymer film interface and the hydrogel interface, and induces the formation of a wrinkle structure. In the specific preparation process, the polymer solution is coated on the second surface and subjected to photocuring treatment to enhance the mechanical strength of the polymer film and the interfacial adhesion with the hydrogel, and then internal stress is pre-stored by drying treatment; when immersed in water, the second surface of the hydrogel expands while the first surface is limited, driving the directional instability of the polymer film interface and the hydrogel interface, and forming a controllable wrinkle structure.

[0062] In one specific embodiment, the temperature in the immersion process is 5-32℃, and the time is 1-60min.

[0063] In the soaking treatment, the temperature and the time are each in the above range, the temperature of the soaking treatment is controlled to be lower than the lower critical solution temperature of the hydrogel (such as poly(N-isopropylacrylamide)), the swelling state of the hydrogel is maintained, the volume shrinkage of the hydrogel due to the temperature rise is avoided, the continuous free swelling of the second surface of the hydrogel is ensured, a stable swelling difference is formed between the adhered first surface and the second surface, the polymer network is driven to diffuse in water to generate an inward shrinkage stress, and then the interface between the polymer film and the hydrogel is destabilized, and finally the wrinkle structure is induced. If the temperature is too high, the hydrogel will shrink, the asymmetric swelling condition will be destroyed, the interface stress will be unbalanced, and it is difficult to form a regular wrinkle structure.

[0064] Exemplarily, in the soaking treatment, the temperature can be any one or a range formed by any two of 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, and 32°C.

[0065] The time can be any one or a range formed by any two of 1 min, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min.

[0066] In an embodiment, in the polymer film / hydrogel composite, the thickness of the polymer film is 0.1-100 μm, for example, can be any one or a range formed by any two 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, and 100 μm.

[0067] Further, in the polymer film / hydrogel composite, the thickness of the polymer film can be preferably 50-100 μm.

[0068] In an embodiment, the mass percentage of the polymer containing a carbon-carbon double bond in the polymer solution is 1%-50%, which can be preferably 10%-50%.

[0069] In an embodiment, the water-soluble monomer containing a carbon-carbon double bond is at least one of acrylamide, acrylic acid, N-isopropylacrylamide, [3-(methacryloylamino)propyl]trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, sodium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and 3-sulfopropyl acrylate.

[0070] When the water-soluble monomer containing carbon-carbon double bond is the above-mentioned substance, the advantage lies in low-cost, easily-obtained raw materials and excellent processing adaptability. The water-soluble monomer containing carbon-carbon double bond has high solubility in water, can be directly prepared into a prepolymer solution without organic solvents, reduces production cost and meets environmental protection requirements; the carbon-carbon double bond has high activity, can be efficiently polymerized by light or heating to form a hydrophilic network structure, endows the hydrogel with high swelling property, biocompatibility and adjustable mechanical property; in addition, the molecular structure of the water-soluble monomer containing carbon-carbon double bond is easy to modify, which is convenient for further functionalization, and comprehensively balances economy, practicability and performance designability.

[0071] In a specific embodiment, the above-mentioned polymer containing carbon-carbon double bond is a polymer containing carbon-carbon double bond, and the chemical structural formula of the above-mentioned polymer containing carbon-carbon double bond is as follows:

[0072] ;

[0073] In the formula, a, b, c, x, y and a' are the mole fractions of the respective component units, and satisfy: 0.1≤(a+a') / (a+a'+b+c+x+y)≤0.18, 0<(b+c) / (a+a'+b+c+x+y)<0.6, 0

[0074] In the present application, the carbon-carbon double bond in the polymer containing carbon-carbon double bond is specifically the carbon-carbon double bond on the acrylic group.

[0075] When the polymer containing carbon-carbon double bond is the above-mentioned substance, crosslinking is initiated by light or heating, the carbon-carbon double bond in the polymer solution and the carbon-carbon double bond in the hydrogel undergo free radical polymerization to form covalent bonds, which significantly improves the interfacial adhesion and avoids delamination.

[0076] In a specific embodiment, the above-mentioned 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.

[0077] In a specific embodiment, the above-mentioned hydrogel is prepared from a raw material system comprising a water-soluble monomer containing carbon-carbon double bond, and specifically comprises: dispersing the water-soluble monomer containing 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 under a 315-400 nm ultraviolet lamp for 0.5-48 h to obtain the above-mentioned hydrogel.

[0078] The specific material of the mold is not particularly limited, and is a conventional type, for example, the material of the mold is polytetrafluoroethylene.

[0079] In an embodiment, the mass percentage of the water-soluble monomer containing a carbon-carbon double bond in the pre-polymer solution 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%. Further, the mass percentage of the water-soluble monomer containing a carbon-carbon double bond in the pre-polymer solution can be preferably 40%-90%, the mass percentage of the cross-linking agent can be preferably 0.2%-1%, and the mass percentage of the initiator can be preferably 1%-5%.

[0080] When the mass percentage of the water-soluble monomer containing a carbon-carbon double bond, the mass percentage of the cross-linking agent, and the mass percentage of the initiator in the pre-polymer solution are each within the above ranges, brittle due to excessive cross-linking or side reactions caused by excessive initiation of the initiator can be reduced while ensuring efficient cross-linking and curing.

[0081] In an embodiment, the light curing treatment is performed under a 315-400 nm ultraviolet lamp for 5-60 min. Further, the light curing treatment can be preferably performed under a 365 nm ultraviolet lamp for 5-30 min.

[0082] In an embodiment, the drying treatment is performed at a temperature of 30-80°C for 5-60 min.

[0083] For example, the temperature in the drying treatment can be any one or a range formed by any two of 30°C, 40°C, 50°C, 60°C, 70°C, and 80°C.

[0084] The time can be any one or a range formed by any two of 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min.

[0085] The specific shape of the hydrogel is not particularly limited. In an embodiment, the shape of the hydrogel includes any one of a cuboid, a cube, and a cylinder.

[0086] In an 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.

[0087] In an embodiment, when the shape of the hydrogel is a cylinder, the diameter of the hydrogel is 5-100 mm, and the height is greater than 2 mm and less than 100 mm.

[0088] If the height of the hydrogel is less than or equal to 2 mm, it is difficult to form obvious and large-area wrinkle structures, which may be due to the insufficient thickness of the hydrogel, resulting in insufficient accumulation of the swelling difference between the first surface and the second surface, and it is difficult to generate sufficient shrinkage stress and drive the interface to be unstable, so that obvious and large-area wrinkle structures do not appear; if the height of the hydrogel exceeds 100 mm, the water diffusion efficiency is reduced and the gravity affects the uniformity of the swelling rate, which may lead to disorderly distribution or local collapse of the wrinkle structure. Therefore, the height is controlled to be greater than 2 mm and less than 100 mm, which can not only ensure effective stress accumulation generated by asymmetric swelling, but also maintain the balance between solvent diffusion kinetics and interface instability, so as to obtain an oriented wrinkle structure.

[0089] The present application does not particularly limit the type of the specific cross-linking agent used above, and a conventional type in the art can be used. Preferably, the cross-linking agent described above can be at least one of N,N-methylenebisacrylamide, polyethylene glycol diacrylate, and polyethylene glycol diglycidyl ether.

[0090] The present application also does not particularly limit the type of the specific initiator used above, and a conventional type in the art can be used. Preferably, the initiator described above can be at least one of ammonium persulfate, potassium persulfate, azobisisobutyronitrile, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, and alpha-ketoglutaric acid.

[0091] In some embodiments, the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is obtained by a preparation method comprising the following processes:

[0092] 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 are mixed and subjected to a first stirring treatment to obtain a product; 1.5 mL of hydrogen peroxide is added to the product and subjected to a second stirring treatment to obtain an epoxidized poly(styrene-butadiene-styrene);

[0093] A mixture consisting of 3.8 mL of acrylic acid and 0.0169 g of hydroquinone is added to 3.5 g of the epoxidized poly(styrene-butadiene-styrene) in 35 mL of toluene and subjected to a third stirring treatment to obtain the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds.

[0094] The present application modifies the poly(styrene-butadiene-styrene) by the above-mentioned processes to obtain the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds, which can be used to prepare the polymer solution described above.

[0095] In some embodiments, in the first stirring treatment, the temperature is 68-72℃, and the time is 1.5-3h.

[0096] In some embodiments, in the second stirring treatment, the temperature is 68-72℃, and the time is 1.5-3h.

[0097] In some embodiments, in the third stirring treatment, the temperature is 70-80℃, and the time is 15-25h.

[0098] The second aspect of the present application provides a surface-creped polymer film / hydrogel composite material prepared by the above-mentioned method for preparing a surface-creped polymer film / hydrogel composite material. Therefore, the surface-creped polymer film / hydrogel composite material has environmental response characteristics, and the creped structure on the surface thereof is micron-sized, which has potential application value in the fields of flexible electronics, biological interface engineering, and intelligent camouflage.

[0099] Hereinafter, the present application will be further described through specific examples.

[0100] Example 1

[0101] The present example provides a method for preparing a surface-creped polymer film / hydrogel composite material, comprising:

[0102] (1) Preparation of poly(styrene-butadiene-styrene) containing carbon-carbon double bonds (double-bond-containing SBS)

[0103] 5g of poly(styrene-butadiene-styrene) (0.0375mmol) was dispersed in 50mL of toluene, then 0.565mL of formic acid (0.0132mol) and 0.05mL of polyethylene glycol-600 (0.083mol) were added, and stirring treatment was carried out at 70℃ for 2h using a magnetic stirrer, then 1.5mL of hydrogen peroxide was added, and stirring was continued at 70℃ for 2h, after cooling, precipitation was carried out using anhydrous ethanol to obtain a first solid, the first solid was washed with deionized water to obtain a clean first solid, and the clean first solid was dried in a vacuum oven at 35℃ overnight to obtain epoxidized poly(styrene-butadiene-styrene) (denoted as epoxidized SBS);

[0104] Disperse 3.5 g of epoxidized SBS (0.0257 mmol) in 35 mL of toluene, then add a mixture composed of 3.8 mL of acrylic acid (0.0548 mol) and 0.0169 g of hydroquinone (0.153 mol), heat to 75°C, stir at 75°C for 20 h with a magnetic stirrer, precipitate with absolute ethanol after cooling, obtain a second solid, wash the second solid with deionized water to obtain a clean second solid, dry the clean second solid in a 35°C vacuum oven overnight to obtain a poly(styrene-butadiene-styrene) containing carbon-carbon double bonds (denoted as double-bond-containing SBS);

[0105] (2) Preparation of a polymer film / hydrogel composite material with surface wrinkles

[0106] Dissolve 2 g of acrylamide, 0.01 g of N,N-methylenebisacrylamide and 0.05 g of α-ketoglutaric acid in 5 g of water, stir thoroughly for 30 min to obtain a prepolymer solution; then inject the prepolymer solution into a polytetrafluoroethylene mold with a rectangular cavity structure, with the lower end and the four sides sealed and the upper end open, seal the polytetrafluoroethylene mold and irradiate under a 365 nm ultraviolet lamp for 2 h, take out the product after irradiation from the mold to obtain a hydrogel with a length of 10 mm, a width of 10 mm and a height of 4 mm;

[0107] Disperse 1 g of double-bond-containing SBS in 10 mL of toluene, stir thoroughly for 6 h, filter with a filter head to obtain a polymer solution;

[0108] Adhere the lower surface of the hydrogel to a common glass sheet, then use a spin coater with a rotation speed of 2000 r / min to spin coat 0.1 mL of the polymer solution on the upper surface of the hydrogel, then place it under a 365 nm ultraviolet lamp for irradiation for 5 min, and then place it in a 40°C oven for drying treatment for 30 min to obtain a polymer film / hydrogel composite material; in the polymer film / hydrogel composite material, the thickness of the polymer film is 57.2 μm;

[0109] Place the polymer film / hydrogel composite material in 25°C water for immersion treatment for 30 min to obtain a polymer film / hydrogel composite material with surface wrinkles.

[0110] Example 2

[0111] The preparation method of the polymer film / hydrogel composite material with surface wrinkles provided in this example is basically the same as that of Example 1, except that:

[0112] The hydrogel is a rectangular solid with a length of 10 mm, a width of 10 mm and a height of 10 mm.

[0113] Example 3

[0114] The preparation method of the surface-roughened polymer film / hydrogel composite provided in the embodiment is basically the same as that in Embodiment 1, except that:

[0115] The prepolymer solution was prepared by dissolving 2 g of N-isopropyl acrylamide, 0.01 g of N,N-methylenebisacrylamide and 0.05 g of alpha-ketoglutaric acid in 5 g of water, and fully stirring for 30 min.

[0116] Comparative Example 1

[0117] The preparation method of the polymer film / hydrogel composite provided in the comparative example is basically the same as that in Embodiment 1, except that:

[0118] The hydrogel was a cuboid with a length of 10 mm, a width of 10 mm and a height of 2 mm.

[0119] Comparative Example 2

[0120] The preparation method of the surface-roughened polymer film / hydrogel composite provided in the comparative example is basically the same as that in Embodiment 1, except that:

[0121] The temperature during the soaking treatment was 50°C, and specifically, the polymer film / hydrogel composite was soaked in water at 50°C for 30 min to obtain the surface-roughened polymer film / hydrogel composite.

[0122] Comparative Example 3

[0123] The preparation method of the hydrogel material provided in the comparative example comprises the following steps:

[0124] 2 g of acrylamide, 0.01 g of N,N-methylenebisacrylamide and 0.05 g of alpha-ketoglutaric acid were dissolved in 5 g of water, and fully stirred for 30 min to obtain a prepolymer solution; the prepolymer solution was injected into a mold with a cuboid cavity structure with a closed bottom and four sides and an open top, the mold was sealed, and then irradiated under a 365 nm ultraviolet lamp for 2 h; the product after irradiation was taken out of the mold to obtain a hydrogel; the hydrogel was soaked in water at 25°C for 30 min to obtain a hydrogel material.

[0125] Performance test

[0126] 1. The nuclear magnetic hydrogen spectrum of poly(styrene-butadiene-styrene) (SBS), epoxidized SBS and SBS containing double bonds in Embodiment 1 of the present application was tested, and the structure is as shown in Figure 1 ; Figure 1 The nuclear magnetic hydrogen spectrum of SBS, epoxidized SBS and SBS containing double bonds in the present application.

[0127] By Figure 1It can be seen that, compared with SBS, two new signal peaks appear in the green part of the nuclear magnetic hydrogen spectrum at 2.71 and 2.95 ppm, corresponding to the chemical shifts of cis-epoxy group and 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 ring opening reaction, the signal peaks at 2.71 and 2.95 ppm are weakened, and the blue part appears new characteristic signal peaks of the acrylic group at 5.87 and 6.15 ppm, indicating the successful introduction of the carbon-carbon double bond, that is, the successful preparation of the double bond-containing SBS, and the chemical structural formula of the double bond-containing SBS is as follows:

[0128] ;

[0129] In the formula, a, b, c, x, y, 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 is calculated according to the nuclear magnetic hydrogen spectrum.

[0130] 2, the surface morphology of the surface wrinkled polymer film / hydrogel composite material in the present application examples 1-3, the polymer film / hydrogel composite material in comparative example 1, the surface rough polymer film / hydrogel composite material in comparative example 2 and the hydrogel material in comparative example 3 were tested by using a confocal microscope with model LEXT OLS5000, and the results are shown in Figures 2-7 , then the surface morphology test results of the surface wrinkled polymer film / hydrogel composite material in examples 1-3 and the surface rough polymer film / hydrogel composite material in comparative example 2 were introduced into the software Analysis application for scanning of the wrinkle wavelength and amplitude, and the corresponding numerical values were obtained (see Table 1); Figure 2 It is a two-dimensional surface wrinkle morphology optical micrograph of the surface wrinkled polymer film / hydrogel composite material in example 1; Figure 3 It is a two-dimensional surface wrinkle morphology optical micrograph of the surface wrinkled polymer film / hydrogel composite material in example 2; Figure 4 It is a two-dimensional surface wrinkle morphology optical micrograph of the surface wrinkled polymer film / hydrogel composite material in example 3; Figure 5 It is a two-dimensional surface wrinkle morphology optical micrograph of the polymer film / hydrogel composite material in comparative example 1; Figure 6 It is a two-dimensional surface wrinkle morphology optical micrograph of the polymer film / hydrogel composite material in comparative example 2; Figure 7 It is a two-dimensional surface morphology optical micrograph of the hydrogel material in comparative example 3.

[0131] Table 1 test results

[0132] Item Wrinkle wavelength (pm) Wrinkle amplitude (pm) 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

[0133] From Figures 2-4 From Table 1, it can be seen that the surface-ridged polymer film / hydrogel composite material in Examples 1-3 has obvious, regular and large-area wrinkle structure, and the wrinkle structure is fine and uniform. The wrinkle wavelength of the surface-ridged polymer film / hydrogel composite material in Example 1 is 41.9 μm, and the amplitude is 17.7 μm; the wrinkle wavelength of the surface-ridged polymer film / hydrogel composite material in Example 2 is 24.2 μm, and the amplitude is 9.2 μm; the wrinkle wavelength of the surface-ridged polymer film / hydrogel composite material in Example 3 is 13.5 μm, and the amplitude is 5.9 μm. The above results show that the wrinkle wavelength and amplitude are related to the thickness of the hydrogel and the water-soluble monomer containing carbon-carbon double bond, and thus the surface-ridged morphology of the polymer film / hydrogel composite material can be adjusted by controlling the thickness of the hydrogel or using different water-soluble monomers containing carbon-carbon double bond. The above results also show that the wrinkle structure on the surface of the surface-ridged polymer film / hydrogel composite material is micron-sized.

[0134] From Figure 5 From Table 1, it can be seen that the surface of the polymer film / hydrogel composite material in Comparative Example 1 does not have obvious and large-area wrinkle structure, which may be due to the fact that the thickness of the hydrogel is insufficient, and the swelling difference between the upper surface and the lower surface is insufficient to induce surface buckling behavior, so that obvious and large-area wrinkle structure does not appear. The surface of the polymer film / hydrogel composite material in Comparative Example 1 does not have obvious and large-area wrinkle structure, and thus the scanning of the wrinkle wavelength and amplitude is not performed.

[0135] From Figure 6 From Table 1, it can be seen that the wrinkle structure on the surface of the surface-rough polymer film / hydrogel composite material in Comparative Example 2 is rough, uneven and irregular, the wrinkle wavelength is 423.5 μm, and the amplitude is 53.9 μm, which shows that the wrinkle wavelength and amplitude of the surface-rough polymer film / hydrogel composite material in Comparative Example 2 are large. The reason may be that when the temperature during the soaking treatment is 50℃, it exceeds the lower critical solution temperature of poly(N-isopropyl acrylamide), and part of the hydrogen bonds in the hydrogel network are destroyed, and the solvent layer of the hydrophobic part of the macromolecular chain is also destroyed, and the hydrogel network changes from loose coil structure to compact colloidal structure, inducing volume shrinkage again, which destroys the surface wrinkle structure, and thus the wrinkle structure is rough, uneven and irregular.

[0136] From Figure 7It can be seen that no wrinkle structure appears on the surface of the hydrogel material in Comparative Example 3, which indicates that the hydrogel in Comparative Example 3 cannot generate a wrinkle structure when swelling in water. No wrinkle structure appears on the surface of the hydrogel material in Comparative Example 3, and no scanning of the wrinkle wavelength and amplitude is performed.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

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, wherein the polymer containing a carbon-carbon double bond is obtained by sequentially subjecting poly(styrene-butadiene-styrene) to epoxidation reaction and acrylic acid modification; The height of the hydrogel is greater than 2 mm and less than 100 mm.

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 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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