A method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material

Abstract

The present invention relates to the technical field of composite material preparation, and in particular to a method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material. The method for constructing the surface wrinkle structure of the polymer film / hydrogel composite material comprises the following steps: dispersing a polymer containing carbon-carbon double bonds in a solvent to obtain a polymer solution; coating the polymer solution on the surface of a substrate, and forming a polymer film after drying; dispersing a water-soluble monomer containing carbon-carbon double bonds, a crosslinking agent, and an initiator in an aqueous solution to obtain a prepolymer solution; contacting the surface of the polymer film with at least a portion of the liquid surface of the prepolymer solution, and crosslinking and curing under light irradiation to obtain a polymer film / hydrogel composite material with a surface wrinkle structure. The present invention can achieve precise control of the wrinkle wavelength and amplitude by controlling the thickness of the polymer film, and can meet the needs of different application scenarios.

Description

Technical Field

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

[0002] Hydrogel is a three-dimensional soft material composed of a hydrophilic polymer network. Due to its high water content, adjustable mechanical properties and excellent biocompatibility, it has shown great application potential in biomedicine, flexible sensing, microfluidic chips, optical regulation and information encryption. Studies have shown that constructing a wrinkled structure on the surface of a hydrogel can precisely control its wettability, adhesion, conductivity and impact resistance. It is an important way to achieve hydrogel surface functionalization and a key direction for promoting the development of hydrogel-based functional devices. However, hydrogels prepared by traditional free radical polymerization are usually carried out in closed molds. Their cross-linked network density is uniform, and there is a lack of modulus gradient or internal stress difference, which makes it difficult to trigger the conditions for the formation of surface wrinkled structures. In addition, hydrogels are prone to swelling or volume collapse under humid or high temperature conditions, resulting in the collapse of the wrinkled structure, which limits their practical application.

[0003] At present, the existing technology mainly uses the pre-stretching method to construct a wrinkled structure on the surface of the hydrogel. For example, the Chinese patent application with publication number CN114437389A discloses an ordered nano-wrinkled cellulose composite membrane with high surface Raman enhancement effect and its preparation method. The double cross-linking strategy induced in the coagulation bath under the assistance of external force is used to prepare an ordered nano-wrinkled cellulose composite membrane with high surface Raman enhancement effect. 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 the calcium ion cross-linked alginate / polyacrylamide hydrogel and then soaking it in an aqueous solution of ferric chloride. Although this method can construct a wrinkled structure on the surface of the hydrogel, it is heavily dependent on the application of external stress, has high requirements for the strength and direction control of the pre-stretching, is complicated to operate, and is prone to introducing residual stress during the pre-stretching process, resulting in a decrease in the mechanical properties of the hydrogel or irreversible deformation.

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

[0005] The present invention provides a method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material. The polymer film / hydrogel composite material with a surface wrinkle structure prepared by this construction method is compatible with various stimulus-responsive hydrogel systems such as light / heat, and its wrinkle structure is micron-sized. In addition, by controlling the thickness of the polymer film, the wavelength and amplitude of the wrinkles can be precisely controlled to meet the needs of different application scenarios.

[0006] The present invention also provides a polymer film / hydrogel composite material with a corrugated structure on the surface, which is prepared by the above-mentioned method for constructing a corrugated structure on the surface of the polymer film / hydrogel composite material; the polymer film / hydrogel composite material with a corrugated structure on the surface is compatible with various stimulus-responsive hydrogel systems such as light / heat, and its corrugated structure is micron-sized, and has potential application value in the fields of biomedicine, flexible sensing, microfluidic chips, optical regulation, etc.

[0007] A first aspect of the present invention provides a method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material, comprising the following steps:

[0008] dispersing a polymer containing a carbon-carbon double bond in a solvent to obtain a polymer solution;

[0009] coating the polymer solution on the surface of a substrate and forming a polymer film with a thickness of 0.1-100 μm after drying;

[0010] Dispersing a water-soluble monomer containing a carbon-carbon double bond, a cross-linking agent, and an initiator in an aqueous solution to obtain a prepolymer solution;

[0011] contacting the surface of the polymer film with at least a portion of the liquid surface of the prepolymer solution, and crosslinking and curing the polymer film under light irradiation to obtain a polymer film / hydrogel composite material having a wrinkled surface structure;

[0012] The polymer containing carbon-carbon double bonds is obtained by sequentially subjecting poly(styrene-butadiene-styrene) to epoxidation reaction and acrylic acid modification.

[0013] In the method for constructing the surface wrinkle structure of the polymer film / hydrogel composite material as described above, the mass percentage of the polymer containing carbon-carbon double bonds in the polymer solution is 1%-50%.

[0014] In the method for constructing the surface wrinkle structure of the 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%.

[0015] In the method for constructing the surface wrinkle structure of the polymer film / hydrogel composite material described above, 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:

[0016] 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.

[0017] In the method for constructing the surface wrinkle structure of the polymer film / hydrogel composite material as described above, the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is obtained by a preparation method comprising the following steps:

[0018] Mixing poly(styrene-butadiene-styrene), formic acid, polyethylene glycol-600 and first toluene and performing a first stirring process to obtain a product; adding hydrogen peroxide to the product and performing a second stirring process, and obtaining epoxidized poly(styrene-butadiene-styrene) after first cooling and first precipitation;

[0019] A mixture of acrylic acid and hydroquinone and the epoxidized poly(styrene-butadiene-styrene) are added to a second toluene for a third stirring treatment, and the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is obtained after a second cooling and a second precipitation.

[0020] In the method for constructing the surface wrinkle structure of the polymer film / hydrogel composite material as described above, 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.

[0021] The method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material as described above, wherein 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;

[0022] and / or, the cross-linking agent is at least one of N,N-methylenebisacrylamide, polyethylene glycol diacrylate, and polyethylene glycol diglycidyl ether;

[0023] And / or, the initiator is at least one of ammonium persulfate, potassium persulfate, azobisisobutyronitrile, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, and α-ketoglutaric acid.

[0024] The method for constructing a surface wrinkle structure of the polymer film / hydrogel composite material as described above, wherein the drying temperature is 30-100° C. and the drying time is 8-48 hours;

[0025] And / or, the cross-linking and curing under light irradiation includes: cross-linking and curing under ultraviolet light irradiation with a wavelength of 315-400 nm for 0.5-48 hours.

[0026] A second aspect of the present invention provides a polymer film / hydrogel composite material having a surface wrinkle structure, which is prepared by the method for constructing a surface wrinkle structure of the polymer film / hydrogel composite material.

[0027] The solution of the present invention has at least the following effects:

[0028] (1) The method for constructing the surface wrinkle structure of the polymer film / hydrogel composite material provided by the present invention realizes self-driven wrinkle forming through the intrinsic contraction of the hydrogel, avoids the strict requirements of the traditional pre-stretching method on force and direction, and simplifies the construction steps of the surface wrinkle structure; (2) The polymer film interface and the hydrogel interface are covalently cross-linked to form a polymer film / hydrogel composite material, which ensures the mechanical reliability of the polymer film / hydrogel composite material, prevents delamination, and extends the service life; (3) By controlling the thickness of the polymer film, the wavelength and amplitude of the wrinkles can be precisely controlled to meet the needs of different application scenarios. (4) The polymer film / hydrogel composite material with a wrinkled surface structure prepared by this construction method is compatible with a variety of stimulus-responsive hydrogel systems such as light / heat, providing a new paradigm for the dynamic reconstruction of smart surfaces; (5) The construction method of the surface wrinkled structure of the polymer film / hydrogel composite material provided by the present invention is simple to operate and has strong versatility, which greatly reduces the cost of obtaining the wrinkled structure on the surface of the hydrogel. The wrinkled morphology can be regulated by controlling the thickness of the polymer film, the water-soluble monomer containing carbon-carbon double bonds, the cross-linking density, etc.; this construction method has both ease of preparation and structural accuracy, and is suitable for wide promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 H NMR spectra of poly(styrene-butadiene-styrene) (SBS), epoxidized SBS and SBS containing double bonds in the present invention;

[0031] Figure 2 This is a photo of the polymer film / hydrogel composite material having a wrinkled surface structure in Example 1 of the present invention;

[0032] Figure 3 This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material having a surface wrinkle structure in Example 1 of the present invention;

[0033] Figure 4 These are optical micrographs of the two-dimensional surface morphology of the polymer film / hydrogel composite material with a surface wrinkle structure in Examples 1-3 of the present invention, the polymer film / hydrogel composite material in Comparative Example 1, and the hydrogel material in Comparative Example 2, wherein Figure 4 a is an optical micrograph of the two-dimensional surface morphology of the polymer film / hydrogel composite material with a wrinkled surface structure in Example 1. Figure 4 b is an optical micrograph of the two-dimensional surface morphology of the polymer film / hydrogel composite material with a wrinkled surface structure in Example 2. Figure 4 c is an optical micrograph of the two-dimensional surface morphology of the polymer film / hydrogel composite material in Example 3, Figure 4 d is an optical micrograph of the two-dimensional surface morphology of the polymer film / hydrogel composite material in Comparative Example 1, Figure 4 e is an optical micrograph of the two-dimensional surface morphology of the hydrogel material in Comparative Example 2;

[0034] Figure 5 The three-dimensional surface morphology optical micrographs of the polymer film / hydrogel composite material with a surface wrinkle structure in Examples 1-2 of the present invention and the polymer film / hydrogel composite material in Comparative Example 1 are shown in FIG. Figure 5 a is an optical micrograph of the three-dimensional surface morphology of the polymer film / hydrogel composite material with a wrinkled surface structure in Example 1. Figure 5 b is an optical micrograph of the three-dimensional surface morphology of the polymer film / hydrogel composite material with a wrinkled surface structure in Example 2. Figure 5 c is an optical micrograph of the three-dimensional surface morphology of the polymer film / hydrogel composite material in Comparative Example 1;

[0035] Figure 6 The surface wrinkle morphology of the polymer film / hydrogel composite material having a wrinkle structure and the heated polymer film / hydrogel composite material in Example 3 of the present invention, wherein Figure 6a is the surface wrinkle morphology of the polymer film / hydrogel composite material having a wrinkle structure on the surface in Example 3 of the present invention, Figure 6 b is the surface wrinkle morphology of the polymer film / hydrogel composite material with a wrinkle structure on the surface after heating. DETAILED DESCRIPTION

[0036] 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.

[0037] It should be noted that the descriptions involving "first", "second", "third", etc. in the present invention are used to distinguish similar objects, and are not used to describe a specific order or sequence, and therefore cannot be understood as a limitation of the present invention.

[0038] In addition, in the specification and claims, "and / or" means at least one of the connected objects, and the character " / " generally indicates that the previous and subsequent related objects are in an "or" relationship.

[0039] A first aspect of the present invention provides a method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material, comprising the following steps:

[0040] dispersing a polymer containing a carbon-carbon double bond in a solvent to obtain a polymer solution;

[0041] coating the polymer solution on the surface of a substrate and forming a polymer film with a thickness of 0.1-100 μm after drying;

[0042] Dispersing a water-soluble monomer containing a carbon-carbon double bond, a cross-linking agent, and an initiator in an aqueous solution to obtain a prepolymer solution;

[0043] contacting the surface of the polymer film with at least a portion of the liquid surface of the prepolymer solution, and crosslinking and curing the polymer film under light irradiation to obtain a polymer film / hydrogel composite material having a wrinkled surface structure;

[0044] The polymer containing carbon-carbon double bonds is obtained by sequentially subjecting poly(styrene-butadiene-styrene) to epoxidation reaction and acrylic acid modification.

[0045] 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.

[0046] 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.

[0047] The present invention does not limit the shape, size, and thickness of the substrate, which can be selected according to actual needs.

[0048] The present invention does not limit the shape and size of the polymer film, which can be selected according to actual needs.

[0049] In the present invention, contacting the surface of the polymer film with at least a portion of the liquid surface of the prepolymerization liquid means that the surface of the polymer film may be in contact with a portion of the liquid surface of the prepolymerization liquid or the entire liquid surface of the prepolymerization liquid.

[0050] The present invention does not specifically limit the specific operation of contacting the surface of the polymer film with at least a portion of the liquid surface of the prepolymer solution. For example, a mold can be used for this operation. The present invention does not specifically limit the specific shape of the mold used and can be selected according to actual needs. For example, a cube or rectangular parallelepiped with a closed bottom and four sides and an open top can be used as the mold.

[0051] When the mold used is a rectangular parallelepiped cavity structure with a closed lower end and four sides and an open upper end, after the prepolymer liquid is injected into the mold, the prepolymer liquid has a total of six liquid levels, namely the upper liquid level, the lower liquid level, the left liquid level, the right liquid level, the front liquid level and the rear liquid level. For example, when the mold is a rectangular parallelepiped cavity structure with a closed lower end and four sides and an open upper end, the prepolymer liquid can be injected into the mold first, and then a polymer film can be covered on the upper liquid level of the prepolymer liquid so that the surface of the polymer film is in contact with the upper liquid level of the prepolymer liquid; the polymer film can also be covered on the inner wall surface of the lower end of the mold first, and then the prepolymer liquid is injected into the mold, and then the polymer film can be covered on the upper liquid level of the prepolymer liquid so that the surface of the polymer film is in contact with the lower liquid level and the upper liquid level of the prepolymer liquid; the polymer film can also be covered on the inner wall surface of the lower end of the mold first, and then the prepolymer liquid is injected into the mold, and then the polymer film can be covered on the upper liquid level of the prepolymer liquid so that the surface of the polymer film is in contact with the lower liquid level and the upper liquid level of the prepolymer liquid; The inner wall surface of the mold is covered with a polymer film, and then the prepolymer liquid is injected into the mold, and then the upper liquid surface of the prepolymer liquid is covered with a polymer film so that the surface of the polymer film is in contact with the left liquid surface, the right liquid surface, the front liquid surface, the rear liquid surface and the upper liquid surface of the prepolymer liquid; the polymer film can also be first covered on the inner wall surface of the lower end and the surrounding areas of the mold, and then the prepolymer liquid is injected into the mold, and then the polymer film is covered on the upper liquid surface of the prepolymer liquid so that the surface of the polymer film is in contact with the upper liquid surface, the lower liquid surface, the left liquid surface, the right liquid surface, the front liquid surface and the rear liquid surface of the prepolymer liquid.

[0052] The object prepared by the present invention is a polymer film / hydrogel composite material with a wrinkled structure on the surface. Specifically, a polymer containing carbon-carbon double bonds is first dispersed in a solvent to obtain a polymer solution, and then the polymer solution is coated on the surface of a substrate and dried to form a polymer film; then a water-soluble monomer containing carbon-carbon double bonds, a crosslinking agent and an initiator are dispersed in an aqueous solution to obtain a prepolymer solution; finally, the surface of the polymer film is contacted with at least a portion of the liquid surface of the prepolymer solution, and cross-linking and curing are carried out under light irradiation. The prepolymer solution is cured under light irradiation to form a hydrogel. During the curing process, the carbon-carbon double bonds in the polymer film and the carbon-carbon double bonds in the hydrogel react through free radical polymerization to covalently crosslink the polymer film interface and the hydrogel interface. At the same time, the volume shrinkage of the hydrogel induces the generation of a wrinkled structure, thereby obtaining a polymer film / hydrogel composite material with a wrinkled structure on the surface.

[0053] The principle of preparing a polymer film / hydrogel composite material having a wrinkled surface structure according to the present invention is described below:

[0054] The surface of the polymer film is brought into contact with at least a portion of the liquid surface of the prepolymer liquid, and the prepolymer liquid is cured under light to form a hydrogel. Simultaneously, during the hydrogel curing process, the carbon-carbon double bonds in the hydrogel react with the carbon-carbon double bonds in the polymer film through free radical polymerization to form a covalently cross-linked polymer film / hydrogel composite material. After the cross-linking and curing is completed, the volume of the hydrogel shrinks due to the decrease in entropy of the polymer cross-linking network and the volatilization of water. However, the elastic modulus of the surface polymer film is usually high, making it difficult to shrink synchronously, resulting in the polymer film being compressed and buckling and wrinkling (according to the elastic buckling theory, when a rigid film (the polymer film of the present invention) is attached to the surface of a shrinking soft substrate (the hydrogel of the present invention), the compressive stress exceeds a critical value, and the rigid film releases energy by forming periodic wrinkles), ultimately obtaining a polymer film / hydrogel composite material having a surface wrinkled structure.

[0055] Furthermore, the thickness of the polymer film may preferably be 50-100 μm.

[0056] When the thickness of the polymer film is within the above range, a polymer film / hydrogel composite material having a micron-scale wrinkled structure on the surface can be prepared.

[0057] The present invention can achieve precise regulation of the wavelength and amplitude of wrinkles by controlling the thickness of the polymer film, which can meet the needs of different application scenarios.

[0058] 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%, and more preferably 10%.

[0059] When the mass percentage of the polymer containing carbon-carbon double bonds in the polymer solution is within the above range, it is conducive to the subsequent free radical polymerization reaction between the carbon-carbon double bonds in the polymer film and the carbon-carbon double bonds in the hydrogel, avoiding problems such as uneven reaction or excessive shrinkage caused by excessive concentration.

[0060] In a specific embodiment, in the above-mentioned prepolymer liquid, the mass percentage of the water-soluble monomer containing a carbon-carbon double bond 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%; in the above-mentioned prepolymer liquid, the mass percentage of the water-soluble monomer containing a carbon-carbon double bond may be preferably 40%-90%, the mass percentage of the cross-linking agent may be preferably 0.2%-1%, and the mass percentage of the initiator may be preferably 1%-5%; in the above-mentioned prepolymer liquid, the mass percentage of the water-soluble monomer containing a carbon-carbon double bond may be further preferably 40%, the mass percentage of the cross-linking agent may be further preferably 0.2%, and the mass percentage of the initiator may be further preferably 1%.

[0061] 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, which is beneficial to improving the reliability of the polymer film / hydrogel composite material.

[0062] In a specific embodiment, the polymer containing carbon-carbon double bonds includes poly(styrene-butadiene-styrene) containing carbon-carbon double bonds, and the chemical structure of poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is as follows:

[0063] 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.

[0064] 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.

[0065] 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 of the polymer film undergo free radical polymerization reaction with the carbon-carbon double bonds in the hydrogel network to form covalent connections, significantly improving the interfacial adhesion and avoiding stratification.

[0066] In one embodiment, the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is obtained by a preparation method comprising the following steps:

[0067] Mixing poly(styrene-butadiene-styrene), formic acid, polyethylene glycol-600 and first toluene and performing a first stirring process to obtain a product; adding hydrogen peroxide to the product and performing a second stirring process, and obtaining epoxidized poly(styrene-butadiene-styrene) after first cooling and first precipitation;

[0068] A mixture of acrylic acid and hydroquinone and epoxidized poly(styrene-butadiene-styrene) are added to a second toluene for a third stirring treatment, and poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is obtained after a second cooling and a second precipitation.

[0069] 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 a polymer film containing carbon-carbon double bonds.

[0070] 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.

[0071] 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.

[0072] 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, and preferably toluene.

[0073] In a specific embodiment, the cross-linking agent is at least one of N,N-methylenebisacrylamide, polyethylene glycol diacrylate, and polyethylene glycol diglycidyl ether, and is preferably N,N-methylenebisacrylamide.

[0074] In a specific embodiment, the initiator is at least one of ammonium persulfate, potassium persulfate, azobisisobutyronitrile, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, and α-ketoglutaric acid, and preferably α-ketoglutaric acid.

[0075] In a specific embodiment, the drying temperature is 30-100°C and the time is 8-48h; the drying temperature may preferably be 60-100°C and the time may preferably be 12-48h; the drying temperature may further preferably be 60°C and the time may further preferably be 12h.

[0076] When the parameters of the drying temperature and time are each within the above range, the solvent can be removed uniformly with gentle heating.

[0077] In a specific embodiment, the above-mentioned cross-linking and curing under light irradiation includes: cross-linking and curing under ultraviolet light with a wavelength of 315-400nm for 0.5-48h; preferably, cross-linking and curing under ultraviolet light with a wavelength of 365-400nm for 2-8h; and further preferably, cross-linking and curing under ultraviolet light with a wavelength of 365nm for 2h.

[0078] When cross-linked and cured for 0.5-48 hours under ultraviolet light with a wavelength of 315-400nm, not only can the prepolymer liquid be cured to form a hydrogel under light irradiation, but also during the curing process, the carbon-carbon double bonds in the polymer film can form covalent connections with the carbon-carbon double bonds in the hydrogel through free radical polymerization reactions. After the curing is completed, the volume shrinkage of the hydrogel induces the formation of a wrinkled structure, thereby obtaining a polymer film / hydrogel composite material with a wrinkled structure on the surface.

[0079] A second aspect of the present invention provides a polymer film / hydrogel composite material having a corrugated surface structure, prepared by the aforementioned method for constructing a corrugated surface structure in a polymer film / hydrogel composite material. This polymer film / hydrogel composite material having a corrugated surface structure is therefore compatible with various stimuli-responsive hydrogel systems, such as those for light and heat. Its micron-sized corrugated structure has potential applications in biomedicine, flexible sensing, microfluidic chips, and optical control.

[0080] The present invention is further described below through specific examples.

[0081] Example 1

[0082] This embodiment provides a method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material, comprising the following steps:

[0083] (1) Preparation of poly(styrene-butadiene-styrene) (SBS) containing carbon-carbon double bonds:

[0084] 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. Subsequently, 1.5 mL of hydrogen peroxide was 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) (epoxidized SBS).

[0085] 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 hours 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 (SBS containing double bonds).

[0086] (2) 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;

[0087] (3) 0.1 mL of the polymer solution was spin-coated on the surface of a glass slide using a spin coater at a speed of 2000 r / min, and then dried in an oven at 60 °C for 12 h to obtain a polymer film with a thickness of 57.2 μm.

[0088] (4) 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 and stir thoroughly for 30 min to obtain a prepolymer solution;

[0089] (5) The prepolymer liquid is injected into a polytetrafluoroethylene mold with a rectangular cavity structure that is closed at the bottom and around and open at the top. Then, a polymer film is covered on the upper liquid surface of the prepolymer liquid. After the polytetrafluoroethylene mold is sealed, it is cross-linked and cured under ultraviolet light with a wavelength of 365 nm for 2 hours. The cross-linked and cured product is taken out of the mold to obtain a polymer film / hydrogel composite material with a wrinkled surface structure.

[0090] Example 2

[0091] The method for constructing the surface wrinkle structure of the polymer film / hydrogel composite material provided in this embodiment is basically the same as that in Example 1, except that:

[0092] (3) 0.1 mL of the polymer solution was spin-coated on the surface of a glass slide using a spin coater at a rotation speed of 500 r / min, and then dried in an oven at 60 °C for 12 h to obtain a polymer film with a thickness of 75.2 μm.

[0093] Example 3

[0094] The method for constructing the surface wrinkle structure of the polymer film / hydrogel composite material provided in this embodiment is basically the same as that in Example 1, except that:

[0095] (4) Dissolve 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 stir thoroughly for 30 min to obtain a prepolymer solution.

[0096] Comparative Example 1

[0097] 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:

[0098] (3) 0.1 mL of the polymer solution was spin-coated on the surface of a glass slide using a spin coater at a rotation speed of 100 r / min, and then dried in an oven at 60 °C for 12 h to obtain a polymer film with a thickness of 124.7 μm.

[0099] Comparative Example 2

[0100] This comparative example provides a method for preparing a hydrogel material, comprising the following steps:

[0101] (1) 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 and stir thoroughly for 30 min to obtain a prepolymer solution;

[0102] (2) The prepolymer liquid is injected into a mold with a rectangular cavity structure that is closed at the bottom and around and open at the top. After the mold is sealed, it is cured under ultraviolet light with a wavelength of 365 nm for 2 hours. The cross-linked and cured product is removed from the mold to obtain a hydrogel material.

[0103] Performance Testing

[0104] 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 hydrogen NMR spectra of SBS, epoxidized SBS and SBS containing double bonds in the present invention are shown in FIG.

[0105] 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:

[0106] 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, calculated based on H NMR spectrum.

[0107] 2. The morphology of the polymer film / hydrogel composite material with a surface wrinkle structure in Example 1 of the present invention was tested using a confocal microscope. The results are as follows: Figure 2 and Figure 3 As shown; Figure 2 This is a photo of the polymer film / hydrogel composite material having a wrinkled surface structure in Example 1 of the present invention; Figure 3 This is an optical micrograph of the two-dimensional surface wrinkle morphology of the polymer film / hydrogel composite material having a wrinkle structure on the surface in Example 1 of the present invention.

[0108] Depend on Figure 2 It can be seen that the polymer film / hydrogel composite material in Example 1 is intact and not damaged, and can be observed to be transparent.

[0109] Depend on Figure 3It can be seen that the polymer film / hydrogel composite material with a wrinkled surface in Example 1 has an obvious wrinkled structure on its surface, and the wrinkled structure can exist stably, indicating that it has a highly stable interface.

[0110] 3. The surface morphology of the polymer film / hydrogel composite materials with surface wrinkles in Examples 1-3 of the present invention, the polymer film / hydrogel composite materials in Comparative Example 1, and the hydrogel material in Comparative Example 2 were tested using a LEXT OLS5000 confocal microscope. The results are as follows: Figure 4 As shown, the surface morphology test results were then imported into the software Analysis application to scan the wrinkle wavelength and amplitude to obtain the corresponding values. The test results are shown in Table 1; Figure 4 These are optical micrographs of the two-dimensional (2D) surface morphology of the polymer film / hydrogel composite materials with a surface wrinkle structure in Examples 1-3 of the present invention, the polymer film / hydrogel composite materials in Comparative Example 1, and the hydrogel material in Comparative Example 2.

[0111] Table 1 Test results

[0112] project Wrinkle wavelength (μm) Wrinkle amplitude (μm) Example 1 20 8.7 Example 2 79 13.5 Example 3 14 7.6 Comparative Example 1 0 0 Comparative Example 2 0 0

[0113] Depend on Figure 4 As shown in Table 1, no wrinkle structure appeared on the surface of the hydrogel material in Comparative Example 2 ( Figure 4 e); Comparative Example 1, the surface of the polymer film / hydrogel composite material did not show obvious wrinkles ( Figure 4 d), which may be because the thickness of the polymer film is too thick and the shrinkage of the hydrogel volume is not enough to induce surface buckling behavior, so no wrinkle structure is observed; the surface of the polymer film / hydrogel composite material with a wrinkle structure in Example 1 has an obvious wrinkle structure ( Figure 4 a), which may be because the shrinkage of the hydrogel volume is sufficient to cause the buckling behavior of the polymer film; the surface of the polymer film / hydrogel composite material with a wrinkled structure in Example 2 has an obvious wrinkled structure ( Figure 4 b), which may be due to the shrinkage of the hydrogel volume being sufficient to cause the buckling behavior of the polymer film, but the wavelength and amplitude showed a significant increase compared with Example 1, which may be because the wavelength and amplitude of the critical characteristic wrinkles are proportional to the thickness of the surface polymer film; the surface of the polymer film / hydrogel composite material with a wrinkled structure in Example 3 has an obvious wrinkled structure ( Figure 4 c), which may be due to the shrinkage of the hydrogel volume being sufficient to cause the buckling behavior of the polymer film, but the wavelength and amplitude show a significant decrease compared with Example 2, which may be due to the reduction in the thickness of the surface polymer film.

[0114] As shown in Table 1, the polymer film / hydrogel composite materials with surface wrinkles in Examples 1-3 have different wrinkle wavelengths and amplitudes. The wrinkle wavelength of the polymer film / hydrogel composite material with surface wrinkles in Example 1 is 20 μm, and the amplitude is 8.7 μm; the wrinkle wavelength of the polymer film / hydrogel composite material with surface wrinkles in Example 2 is 79 μm, and the amplitude is 13.5 μm; and the wrinkle wavelength of the polymer film / hydrogel composite material with surface wrinkles in Example 3 is 14 μm, and the amplitude is 7.6 μm. These results indicate that the wrinkle wavelength and amplitude are related to the thickness of the polymer film and the water-soluble monomer containing carbon-carbon double bonds. Therefore, the surface wrinkle morphology of the polymer film / hydrogel composite material can be adjusted by controlling the thickness of the polymer film or using different water-soluble monomers containing carbon-carbon double bonds. These results demonstrate that the wrinkle structure of the polymer film / hydrogel composite material is micrometer-sized.

[0115] 4. The surface morphology of the polymer film / hydrogel composite material with a surface wrinkle structure in Examples 1-2 of the present invention and the polymer film / hydrogel composite material in Comparative Example 1 were tested using a confocal microscope. The results are as follows: Figure 5 As shown; Figure 5 These are optical micrographs of the three-dimensional (3D) surface morphology of the polymer film / hydrogel composite material having a surface wrinkle structure in Examples 1-2 of the present invention and the polymer film / hydrogel composite material in Comparative Example 1.

[0116] Depend on Figure 5 It can be seen from the 3D morphology analysis that the thickness of the polymer film significantly affects the wrinkle structure on the surface of the polymer film / hydrogel composite material: the thinner the polymer film (Example 1, Figure 5 a) forming regular wrinkles with a wavelength of 20 μm and an amplitude of 8.7 μm; increasing the thickness of the polymer film (Example 2, Figure 5 b) causes the wrinkle wavelength to increase significantly to 79 μm and the amplitude to 13.5 μm; and when the thickness of the polymer film exceeds the critical value (Comparative Example 1, Figure 5 c), no wrinkle structure appears on the surface, and the wavelength and amplitude are both 0 μm, confirming that a controllable transition from micron-scale wrinkles to a completely smooth surface can be achieved by precisely controlling the thickness of the polymer film.

[0117] 5. The polymer film / hydrogel composite material having a wrinkled surface structure in Example 3 was heated to 50° C. to obtain a polymer film / hydrogel composite material having a wrinkled surface structure after heating; the morphology of the polymer film / hydrogel composite material having a wrinkled surface structure after heating was tested using a confocal microscope. The results were as follows: Figure 6 As shown; Figure 6The surface wrinkle morphology of the polymer film / hydrogel composite material having a surface wrinkle structure in Example 3 of the present invention and the polymer film / hydrogel composite material having a surface wrinkle structure after heating.

[0118] Depend on Figure 6 It can be seen that the surface of the polymer film / hydrogel composite material with a wrinkled structure in Example 3 has an obvious wrinkled structure, which is a spontaneously constructed surface wrinkle morphology. When the temperature rises to 50°C, the surface wrinkle morphology of the polymer film / hydrogel composite material with a wrinkled structure is reconstructed. This may be because when the temperature rises to 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 hydrogel volume to shrink again, so that its surface wrinkle morphology is reconstructed, showing the dynamic regulation ability of the wrinkle morphology.

[0119] 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 constructing a surface wrinkle structure of a polymer film / hydrogel composite material, characterized in that: The following steps are involved: dispersing a polymer containing a carbon-carbon double bond in a solvent to obtain a polymer solution; coating the polymer solution on the surface of a substrate and forming a polymer film with a thickness of 50-100 μm after drying; Dispersing a water-soluble monomer containing a carbon-carbon double bond, a cross-linking agent, and an initiator in an aqueous solution to obtain a prepolymer solution; contacting the surface of the polymer film with at least a portion of the liquid surface of the prepolymer solution, and crosslinking and curing the polymer film under light irradiation to obtain a polymer film / hydrogel composite material having a wrinkled surface structure; The polymer containing carbon-carbon double bonds is obtained by sequentially subjecting poly(styrene-butadiene-styrene) to epoxidation reaction and acrylic acid modification; The mass percentage of the polymer containing carbon-carbon double bonds in the polymer solution is 1%-50%.

2. The method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material according to claim 1, 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%.

3. The method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material according to claim 1, characterized in that: The polymer containing carbon-carbon double bonds is poly(styrene-butadiene-styrene) containing carbon-carbon double bonds, and the chemical structural formula 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 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.

4. The method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material according to claim 3, characterized in that: The poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is obtained by a preparation method comprising the following steps: Mixing poly(styrene-butadiene-styrene), formic acid, polyethylene glycol-600 and first toluene and performing a first stirring process to obtain a product; adding hydrogen peroxide to the product and performing a second stirring process, and obtaining epoxidized poly(styrene-butadiene-styrene) after first cooling and first precipitation; A mixture of acrylic acid and hydroquinone and the epoxidized poly(styrene-butadiene-styrene) are added to a second toluene for a third stirring treatment, and the poly(styrene-butadiene-styrene) containing carbon-carbon double bonds is obtained after a second cooling and a second precipitation.

5. The method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material 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.

6. The method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material according to claim 1, characterized in that: 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; and / or, the cross-linking agent is at least one of N,N-methylenebisacrylamide, polyethylene glycol diacrylate, and polyethylene glycol diglycidyl ether; And / or, the initiator is at least one of ammonium persulfate, potassium persulfate, azobisisobutyronitrile, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, and α-ketoglutaric acid.

7. The method for constructing a surface wrinkle structure of a polymer film / hydrogel composite material according to claim 1, characterized in that: The drying temperature is 30-100°C and the drying time is 8-48h; And / or, the cross-linking and curing under light irradiation includes: cross-linking and curing under ultraviolet light irradiation with a wavelength of 315-400 nm for 0.5-48 hours.

8. A polymer film / hydrogel composite material having a corrugated surface, characterized in that: The polymer film / hydrogel composite material is prepared by the method for constructing a surface wrinkle structure of the polymer film / hydrogel composite material according to any one of claims 1 to 7.

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