Flexible strong and tough waterborne thin films, methods of making and applications thereof

Abstract

The application discloses a flexible and tough water-vapor film, a preparation method and application thereof. The flexible and tough water-vapor film comprises a nanofiber skeleton formed by interweaving organic nanofibers and having a three-dimensional network structure, and a functional polymer material distributed at least in the interior of the nanofiber skeleton and used at least for connecting part of the organic nanofibers in the nanofiber skeleton. The water-vapor film has excellent flexibility, can generate energy and detect ions based on the water-vapor effect, has low cost, is easy to integrate, has good reliability, has long service life, and is suitable for being applied to wearable devices as a water-vapor power generation device, an ion sensor and the like, can adapt to various motion scenes, and has wide application prospect.

Description

Technical Field

[0001] This invention relates to a water-voltaic power generation device, and more particularly to a flexible and tough high-performance water-voltaic thin film, its preparation method and application, belonging to the field of water-voltaic technology. Background Technology

[0002] Evaporation-driven hydrovoltaics is an emerging environmental energy capture technology that can continuously generate electricity through the evaporation or flow of water. Its working mechanism utilizes ambient thermal energy to drive water evaporation through nanoscale channels within nanomaterials. Due to the presence of overlapping electric double layers within these channels, they exhibit ion selectivity, resulting in the directional migration of specific charged ions and generating voltage output. This voltage is stable, continuous, and spontaneously generated, making it a novel paradigm for environmental energy capture with the potential to power wearable electronic devices.

[0003] Because ions in plasma have a shielding effect on the electric double layer, the voltage and current signals of devices based on the water-voltaic effect are directly affected by the ion concentration in the solution. Based on this, evaporation-driven water-voltaic devices also possess potential ion-sensing characteristics; however, related research is currently very limited.

[0004] Existing water-based photovoltaic devices are mostly thin films formed by nanoparticle coating or spraying. Due to the lack of bonding mechanisms between nanomaterials, their mechanical properties and stability are poor. In addition, the channels formed by the nanomaterials that constitute evaporation-driven water-based photovoltaic devices are currently difficult to precisely control in size, resulting in weak solid-liquid interface interactions and low output voltage (~1V) and current of the devices. Summary of the Invention

[0005] The main objective of this invention is to provide a flexible and tough high-performance water-based thin film, its preparation method and application, thereby overcoming the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] One aspect of the present invention provides a flexible and tough hydrophobic film, comprising:

[0008] Nanofiber framework, which is formed by interwoven organic nanofibers and has a three-dimensional network structure;

[0009] In addition, a functionalized polymer material, which is at least distributed within the nanofiber framework and is used to connect at least a portion of the organic nanofibers to each other.

[0010] Furthermore, the water-voltaic film of this application contains abundant nanoscale channels, and the functionalized polymer materials therein can exhibit morphologies such as adhesion, binding, and local coating of organic nanofibers, thereby significantly improving the mechanical properties of the water-voltaic film, such as structural strength and stability. Moreover, due to the presence of functionalized polymer materials, the size of organic nanofibers changes, thereby allowing the size of the formed nanoscale channels to be controllably adjusted. The chemical properties of the surface of organic nanofibers also change due to the addition of functionalized polymer materials, such as an increase in surface zeta potential, which in turn greatly enhances the water-voltaic performance of the water-voltaic film.

[0011] In one embodiment, the porosity of the nanofiber skeleton is above 15%, preferably above 50%, and more preferably 70% to 90%.

[0012] In one embodiment, the pore size of the pores contained in the nanofiber skeleton is 10 nm to 2000 nm, preferably 10 nm to 800 nm.

[0013] In one embodiment, the diameter of the organic nanofiber is 10 nm to 10 μm, preferably 10 nm to 2 μm, and more preferably 10 nm to 800 nm. If the diameter of the organic nanofiber is too large, the pore size of the nanoscale channel will be unsatisfactory, resulting in poor water resistance. Conversely, if the diameter of the organic nanofiber is too small, the pore size of the nanoscale channel will be too small, resulting in excessive flow resistance, which will also lead to poor water resistance.

[0014] In one embodiment, the organic nanofibers are made of at least one of polyurethane, silk fibroin, polylactic acid, epoxy resin, polyacrylonitrile, polyvinyl alcohol, nylon 66, and butadiene-styrene block copolymer.

[0015] In one embodiment, the functionalized polymer material is also distributed on the surface of the nanofiber framework.

[0016] In one embodiment, the functionalized polymer material at least partially coats the surface of the organic nanofibers, and the diameter of the composite fiber composed of the functionalized polymer material and the nanofibers can be adjusted by adjusting the coating thickness.

[0017] In one embodiment, the functionalized polymer material includes, but is not limited to, at least one of oxidized polyurethane, epoxy resin, polyacrylonitrile, nylon 66, silk fibroin, carboxylated polystyrene, aminolated polystyrene, and sulfonate-modified polystyrene.

[0018] In one embodiment, the content of the functionalized polymer material in the water-based film is 1 wt% to 30 wt%, preferably 10 wt% to 20 wt%. If the content of the functionalized polymer material is too high, it will block the nanoscale channels within the nanofiber framework; conversely, if the content of the functionalized polymer material is too low, the mechanical properties of the water-based film, such as toughness, will be poor.

[0019] In one embodiment, the thickness of the water-based film is 100 nm to 500 μm, preferably 1 μm to 80 μm. If the thickness is too small, the number of nanoscale channels is small, resulting in poor performance; if the thickness is too large, the water will not evaporate sufficiently, and the performance will also decrease.

[0020] In one embodiment, the width of the water-based film is 0.1 to 7.5 cm, preferably 1.5 to 7.5 cm.

[0021] In one embodiment, the porosity of the water-voltaic thin film is 50% to 90%. Within this porosity range, the water-voltaic thin film exhibits ideal mechanical properties such as flexibility and toughness, and it also forms abundant nanoscale channels with suitable pore sizes, thus enabling the water-voltaic thin film to also exhibit good water-voltaic power generation performance.

[0022] The functionalized polymer material may or may not have polar functional groups. Its main function is to bind organic nanofibers, stabilizing the porous network framework structure without blocking the nanoscale channels within the porous network. Especially for non-polar functionalized polymer materials, they cannot completely coat the organic nanofibers; otherwise, the surface of the nanoscale channels would be non-polar, causing the water-repellent film to lose its water-repellent properties.

[0023] The water-voltaic film of the present invention has good flexibility and excellent toughness due to the above-mentioned structural design. After absorbing water, based on the water-voltaic effect, water can flow smoothly in the nanoscale channel and form a flowing potential under the drive of evaporation, thereby generating electricity quickly, efficiently and continuously, and with relatively low requirements for the purity of the water source.

[0024] Another aspect of the invention provides the use of the flexible and tough hydrovoltaic film in the preparation of hydrovoltaic power generation equipment or ion detection equipment.

[0025] The hydroelectric power generation equipment or ion detection equipment can be flexible equipment.

[0026] The photovoltaic power generation equipment or ion detection equipment can be a wearable device.

[0027] Another aspect of the present invention provides a flexible functional device comprising the aforementioned flexible and tough hydrophobic film.

[0028] In one embodiment, the flexible functional device further includes a first electrode and a second electrode, which are spaced apart and electrically connected to the water-voltaic thin film, respectively.

[0029] In one embodiment, the first electrode and the second electrode are respectively connected to a first end and a second end of the water-based thin film, with the first end and the second end positioned opposite each other. In some cases, the first end and the second end may be either the two ends of the water-based thin film in the length direction or the two ends in the width direction.

[0030] In one embodiment, the distance between the first electrode and the second electrode in a specified direction is 0.2 to 4.2 cm, and the specified direction is the direction from the first end to the second end.

[0031] In one embodiment, the first electrode and the second electrode may be formed of an inert material, including but not limited to at least one of platinum, gold, carbon black, carbon nanotubes, graphene, ITO glass, FTO glass, and carbon cloth.

[0032] In one embodiment, the flexible functional device includes a hydroelectric power generation device or an ion sensor device, etc.

[0033] Another aspect of the present invention provides a method for preparing the flexible and tough water-based thin film, comprising:

[0034] S1. Provide an organic nanofiber precursor solution, and use the precursor solution as a spinning solution for electrospinning to obtain an electrospun nanofiber membrane as a nanofiber skeleton.

[0035] S2. Introduce functionalized polymer materials into the electrospun nanofiber membrane and connect at least some of the organic nanofibers to each other.

[0036] In one embodiment, the precursor solution comprises an organic material with a molecular weight of 10w to 1000w and an organic solvent.

[0037] The organic materials include, but are not limited to, at least one of polyurethane, silk fibroin, epoxy resin, polyacrylonitrile, polyvinyl alcohol, nylon 66, and butadiene-styrene block copolymer.

[0038] The organic solvents include, but are not limited to, any one or a combination of two or more of methanol, ethanol, formic acid, acetic acid, tetrahydrofuran, dichloromethane, cyclohexane, epoxy resin, N,N dimethylformamide, and acetone.

[0039] In one embodiment, the concentration of the precursor solution is 1 wt% to 30 wt%, preferably 5 wt% to 25 wt%. If the concentration is too high, the electrospun fibers will be too coarse. Conversely, if the concentration is too low, it will be difficult to spin uniform fibers.

[0040] In one embodiment, the electrospinning process parameters include: spinning voltage of 3-50kV, spinning flow rate of 0.1-5mL / h, spinning distance of 1-20cm, spinning time of 1-20h, receiving roller speed of 50-6000rpm, ambient temperature of 20℃-30℃, and humidity of 20%-80%.

[0041] In one embodiment, step S2 specifically includes: contacting the functionalized polymer material with the electrospun nanofiber membrane using at least one of the methods of dip coating, spray coating, or blade coating, and allowing a portion of the functionalized polymer material to enter the electrospun nanofiber membrane, so as to connect at least a portion of the organic nanofibers to each other. Taking dip coating as an example, if the functionalized polymer material used is silk fibroin, the concentration of the silk fibroin solution used in step S2 is preferably 0.001 wt% to 10 wt%.

[0042] In one embodiment, the preparation method further includes:

[0043] S3. The composite fiber membrane obtained in step S2 is dried at 50-200°C.

[0044] In one embodiment, the preparation method further includes repeating steps S2-S3 more than twice. By adjusting the number of repetitions of steps S2-S3, the content of functionalized polymeric materials in the water-voltaic film can be easily adjusted, thereby controlling the water-voltaic properties of the water-voltaic film.

[0045] The method for preparing the water-voltaic thin film provided by this invention is simple, easy to operate, low in cost, and highly controllable. By introducing functionalized polymer materials into a three-dimensional porous framework structure composed of organic nanofibers, the mechanical properties and surface zeta potential of the water-voltaic thin film are enhanced, and the nanoscale channel size is controllably adjusted, thereby significantly improving the mechanical and water-voltaic properties of the water-voltaic thin film.

[0046] Another aspect of the present invention provides a method for generating hydroelectric power, comprising:

[0047] Provide the aforementioned flexible functional device;

[0048] The first end of the water-voltaic film in the flexible functional device is brought into contact with water, an aqueous solution, or water vapor, thereby generating electricity from the flexible functional device.

[0049] Another aspect of the present invention provides an ion detection method, comprising:

[0050] Provide the aforementioned flexible functional device;

[0051] By bringing the aqueous phase system containing ions into contact with the first end of the water-voltaic thin film in the flexible functional device, at least the type and / or concentration of ions in the aqueous phase system can be detected.

[0052] Another aspect of the present invention provides a wearable device comprising the aforementioned flexible functional device.

[0053] Compared with the prior art, the advantages of the present invention include:

[0054] (1) By introducing functionalized polymer materials into the nanofiber skeleton, the mechanical properties and surface zeta potential of the water-voltaic film are enhanced, and the nanoscale channel size is controllable, thereby achieving a significant improvement in the performance of the evaporation-driven water-voltaic device.

[0055] (2) The provided water-voltaic film based on electrospinning technology has abundant, interconnected nanopores and excellent mechanical properties. These nanopores can form nanoscale channels, thereby endowing the water-voltaic film with excellent water-voltaic properties. This allows the water-voltaic film of the present invention to obtain energy from ambient water through natural evaporation, thus serving as an ideal power source for wearable electronic / electrical devices. Furthermore, by connecting multiple water-voltaic films in series and parallel, an ideal DC power supply system can be built to obtain high-quality clean energy.

[0056] (3) The provided water-based thin film preparation process is simple, easy to implement, easy to achieve large-area preparation, low cost, green and environmentally friendly, and widely applicable.

[0057] (4) The provided water-voltaic thin film also has ion sensing performance and can be used to prepare self-powered ion sensors. It can realize innovative, flexible, and stable output flexible ion sensors, which have broad application prospects in the field of smart wearables and environmental ion monitoring. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the structure of a flexible functional device based on an ultra-tough hydrophobic thin film in Example 1;

[0059] Figure 2 This is a SEM image of a water-based photovoltaic film from Example 1;

[0060] Figure 3 This is a graph showing the changes in the diameter and silk fibroin loading of composite fibers formed after the electrospun nanofiber skeleton is immersed in a silk fibroin aqueous solution for different numbers of times.

[0061] Figure 4 The graph shows the Zta potential changes of the water-voltaic film formed after the electrospun nanofiber skeleton is immersed in the silk fibroin aqueous solution for different numbers of times.

[0062] Figure 5 This is one of the strain-stress variation diagrams of water-coated films formed after the electrospun nanofiber skeleton is immersed in silk fibroin aqueous solution for different numbers of times;

[0063] Figure 6 This is the second strain-stress variation diagram of a water-coated film formed after the electrospun nanofiber skeleton is immersed in a silk fibroin aqueous solution for different numbers of times.

[0064] Figure 7 This is a photograph of a water-based film from Example 1;

[0065] Figure 8 yes Figure 7 Electron micrograph of the cross-section of the water-based thin film shown;

[0066] Figure 9 This is a photograph of a water-based photovoltaic power generation device from Example 1;

[0067] Figure 10 This is a test diagram of the power generation performance of a water-voltaic thin film in Example 1;

[0068] Figure 11 This is a test graph showing the open-circuit voltage response of the water-coated nanofiber skeleton formed by immersing it in an aqueous solution of silk fibroin 1, 3, and 5 times in Example 1 when it is used to prepare a flexible functional device for different concentrations of sodium chloride solution. Detailed Implementation

[0069] In view of the shortcomings of existing technologies, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention, which mainly relates to a flexible and tough high-performance water-based photovoltaic film, its preparation method, and its applications. This invention increases the mechanical strength of the water-based photovoltaic film by using functionalized polymer materials to adhere to and / or bind and / or encapsulate organic nanofibers to form a three-dimensional network framework, while simultaneously making it flexible, thus constructing a flexible and ultra-tough water-based photovoltaic film that can meet its stable performance under different environmental conditions. This water-based photovoltaic functional layer can be used in power / energy generation devices, ion concentration sensors, and wearable electronic devices, and is not limited by water sources, meeting the usage requirements under different environmental conditions and states.

[0070] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0071] See Example 1 Figure 1 and Figure 2 The flexible functional device based on an ultra-tough water-based thin film provided in this embodiment includes a water-based thin film 1 and a non-intersecting top electrode 2 (also known as the first electrode) and bottom electrode 3 (also known as the second electrode). The top electrode 2 and the bottom electrode 3 are electrically connected to the top and bottom ends of the water-based thin film 1, respectively.

[0072] Among them, the water-based film 1 is mainly formed by electrospun nanofiber skeleton 4 and silk fibroin. The electrospun nanofiber skeleton is formed by multiple electrospun nylon 66 nanofibers interwoven, and silk fibroin is modified on the surface and inside of the electrospun nanofiber skeleton.

[0073] The thickness of the water-based thin film 1 can be set to 500nm to 500μm, its vertical dimension (which can be defined as length or height) can be set to 1.8 to 4.2cm, and its horizontal dimension (which can be defined as width) can be set to 1.5 to 7.5cm.

[0074] The top electrode 2 and bottom electrode 3 are formed using chemically inert materials such as platinum, gold, carbon black, carbon nanotubes, graphene, ITO glass, FTO glass, and carbon cloth, with carbon black being the preferred material. The top electrode 2 can be strip-shaped, and the bottom electrode 3 can be L-shaped. The distance between the top electrode 2 and the bottom electrode 3 along the length (or height) of the water-voltaic film 1 can be set to 0.2–4.2 cm.

[0075] One type of water-based photovoltaic thin film can be prepared by the following process:

[0076] S1. Dissolve nylon 66 in formic acid to form a spinning solution with a concentration of 20wt%.

[0077] S2. Electrospinning is performed on the spinning solution. The electrospinning parameters are set as follows: spinning voltage 30kV, spinning flow rate 0.5mL / h, spinning distance 5cm, receiving roller speed 3000r / min, ambient temperature 25℃, humidity 70%, and spinning time 2.5h to obtain an electrospinned nanofiber framework, which can be considered as an electrospinned nanofiber membrane. Its scanning electron microscope image is shown below. Figure 2 As shown, many nanoscale pores can be seen between the electrospun nanofibers.

[0078] S3. The above electrospun nanofiber skeleton is immersed in a 0.001wt% silk fibroin aqueous solution for 10 seconds, then removed and dried on a hot plate at a temperature of about 80°C.

[0079] Performing step S3 more than 0 times can yield water-based films with different compositions. Please refer to... Figure 3 If step S3 is performed 0-5 times, i.e., the electrospun nanofiber skeleton is immersed in a silk fibroin aqueous solution 0-5 times, the mass of silk fibroin loaded on the surface of the electrospun nanofibers and the diameter of the resulting composite fibers will increase with the number of immersions. Furthermore, the Zeta potential of the water-based film also increases with the number of immersions, reaching its maximum value at 4 immersions. Figure 4 As shown. Furthermore, with increasing impregnation cycles, the elastic modulus and ductility of the water-based film will also change accordingly, such as... Figures 5-6 As shown.

[0080] If these water-based films are assembled into structures such as Figure 1 The water-volt power generation devices shown will have a water-volt voltage between 0 and 6V, which indicates that the amount of modification with functionalized polymer materials such as silk fibroin has a significant impact on the open-circuit voltage and short-circuit current of the water-volt film.

[0081] When step S3 is performed three times, the resulting water-based thin film is as follows: Figure 7 As shown, it is approximately 45 μm thick and contains about 12 wt% silk fibroin. The surface of some electrospun nanofibers is coated with silk fibroin with a thickness of approximately 28 nm. Figure 8 As shown.

[0082] The structure of the aforementioned water-voltaic thin-film assemblies for water-voltaic power generation devices can be found in [reference needed]. Figure 1 If the top and bottom of the water-based film are placed in air and water respectively, and the area submerged in water is defined as the first region 1a and the area exposed to air is defined as the second region 1b, then the ambient heat will drive the water to evaporate and flow from the first region to the second region through the nanoscale channels inside the water-based film, forming a flowing potential.

[0083] Figure 9 It shows the use of Figure 7 The water-voltaic thin-film assembly shown is a water-voltaic power generation device (referred to as experimental device 1), and its power generation performance is as follows: Figure 8 As shown, under conditions of 28% humidity and 28°C, this water-voltaic power generation device can generate an open-circuit voltage higher than 5V, which is much higher than that of similar water-voltaic generators, indicating that the water-voltaic film has a high water-voltaic voltage.

[0084] As a control, if the same method as experimental device 1 is used... Figure 2 The electrospun fiber membrane assembled water-voltaic power generation device shown (referred to as control device 1) has an open-circuit voltage of 0.5V in an environment with 28% humidity and 28°C temperature.

[0085] In addition, self-powered ion sensor devices can also be assembled using the aforementioned water-voltaic thin film, the structure of which can be found in [reference needed]. Figure 1 If the top and bottom of the water-based film are placed in air and in an ionic solution, respectively, and the region immersed in the ionic solution is defined as the first region 1a and the region exposed to air is defined as the second region 1b, then the ambient heat will drive the water to evaporate and carry the ions in the solution through the nanoscale channels inside the water-based film, flowing from the first region to the second region. The ion concentration gradient constructed in the first region will cause a concentration diffusion potential to be formed between the top and bottom electrodes.

[0086] If the width of the water-voltaic film in the aforementioned self-powered ion sensor is set to 1.5–7.5 cm and the height to 1.8–4.2 cm, and the open-circuit voltage and short-circuit current are tested respectively, it can be found that the width of the water-voltaic film has little effect on its open-circuit voltage, but a greater effect on its short-circuit current. This is because the resistance of the water-voltaic film is directly proportional to its height and inversely proportional to its width and thickness. Therefore, when the width of the water-voltaic film increases, its resistance decreases accordingly, and the short-circuit current increases. When used as a self-powered ion sensor, the response of the open-circuit voltage of the water-voltaic film to ion concentration is the primary consideration.

[0087] If adopted Figure 3 The water-voltaic thin film assembly shown Figure 1 The self-powered ion sensor device shown (referred to as experimental device 2) has a width of 1.5 cm and a height of 4 cm. Different concentrations of sodium chloride solution are used as the ion solution. According to the electrokinetic theory, the open-circuit voltage is inversely proportional to the conductivity of the solution. When the ion concentration of the added sodium chloride solution increases, the water voltage decreases significantly, indicating a sensitive response. Its response range is 0.5 μM to 1 M, and the response change is as follows: Figure 10 As shown, this indicates that the self-powered ion sensor has good performance in ion sensing and can meet the needs of physiological monitoring (such as sweat), showing broad application prospects in the fields of life and health and medical monitoring. Furthermore, the experimental device 2 exhibits different response voltages for ions of different valence states. Specifically, under the same ion solution concentration, the experimental device 2 has a lower response voltage for higher valence ions.

[0088] Referring to the fabrication method of experimental device 2, the following will be used Figure 2The electrospun nanofiber framework shown was impregnated in a 0.001 wt% silk fibroin aqueous solution 1, 3, and 5 times to obtain a water-voltaic thin film, which was then used to fabricate a self-powered ion sensor. Its performance was tested, and the results are as follows: Figure 11 As shown.

[0089] As a control, if the same method as experimental device 2 is used... Figure 2 The electrospun fiber membrane assembly shown is a self-powered ion sensor device (referred to as control device 2), which has a response range of 50 μM to 100 mM for sodium chloride solutions of different concentrations.

[0090] Example 2

[0091] The structure and fabrication method of the flexible functional device in this embodiment are basically the same as those of experimental device 1, except that the material used to fabricate the nanofiber skeleton is replaced with a polyurethane (PU) electrospun film when fabricating the water-based photovoltaic film. The device in this embodiment has an open-circuit voltage of 1.1V under 28% humidity and 28°C conditions, and its response range to sodium chloride solutions of different concentrations is 50μM to 50mM.

[0092] Example 3

[0093] A method for fabricating a flexible functional device according to this embodiment includes:

[0094] S1. Dissolve polyacrylonitrile (PAN) in N'N-dimethylformamide solvent to form a spinning solution with a concentration of 18wt%.

[0095] S2. Electrospinning is performed on the spinning solution. The electrospinning parameters are set as follows: spinning voltage 50kV, spinning flow rate 0.1mL / h, spinning distance 1cm, receiving roller speed 50r / min, ambient temperature 25℃, humidity 70%, and spinning time 2.5h to obtain an electrospinned nanofiber skeleton.

[0096] S3. The above electrospun nanofiber skeleton is immersed in an aqueous solution of 5 wt% polyurethane oxide for 10 seconds, then removed and dried on a hot plate at a temperature of about 80°C to obtain a water-coated film.

[0097] S4. Referring to the structure and fabrication method of experimental device 1, the water-based thin film is fabricated into a flexible functional device.

[0098] The device in this embodiment has an open-circuit voltage of 0.7V under 28% humidity and 28°C temperature conditions, and its response range for sodium chloride solutions of different concentrations is 100μM to 5mM.

[0099] Example 4

[0100] A method for fabricating a flexible functional device according to this embodiment includes:

[0101] S1. Dissolve polyurethane in N'N-dimethylformamide solvent to form a spinning solution with a concentration of 12wt%.

[0102] S2. Electrospinning is performed on the spinning solution. The electrospinning parameters are set as follows: spinning voltage 3kV, spinning flow rate 1mL / h, spinning distance 5cm, receiving roller speed 500r / min, ambient temperature 25℃, humidity 70%, and spinning time 2.5h to obtain an electrospinned nanofiber skeleton.

[0103] S3. A 1 wt% carboxylated polystyrene acetone solution is uniformly sprayed onto the above electrospun nanofiber skeleton at a spray flow rate of 2 mL / min, a spray distance of 7.5 cm, and a spray time of 2 min. Then, it is placed on a hot plate at a temperature of about 80°C to dry, thereby obtaining a water-coated film.

[0104] S4. Referring to the structure and fabrication method of experimental device 1, the water-based thin film is fabricated into a flexible functional device.

[0105] The device in this embodiment has an open-circuit voltage of 2.5V under 28% humidity and 28°C temperature conditions, and its response range for sodium chloride solutions of different concentrations is 5μm to 500mM.

[0106] Example 5

[0107] A method for fabricating a flexible functional device according to this embodiment includes:

[0108] S1. Dissolve the butadiene-styrene block copolymer in tetrahydrofuran solvent to form a spinning solution with a concentration of 5.5 wt%.

[0109] S2. Electrospinning is performed on the spinning solution. The electrospinning parameters are set as follows: spinning voltage 50kV, spinning flow rate 5mL / h, spinning distance 20cm, receiving roller speed 6000r / min, ambient temperature 25℃, humidity 70%, and spinning time 2.5h to obtain an electrospinned nanofiber skeleton.

[0110] S3. A 10wt% polyacrylonitrile aqueous solution is uniformly coated onto the electrospun nanofiber skeleton and then dried on a hot plate at a temperature of about 80°C to obtain a water-coated film.

[0111] S4. Referring to the structure and fabrication method of experimental device 1, the water-based thin film is fabricated into a flexible functional device.

[0112] The device in this embodiment has an open-circuit voltage of 1.6V under 28% humidity and 28°C temperature conditions, and its response range for sodium chloride solutions of different concentrations is 50μM~200mM.

[0113] Example 6

[0114] The structure and fabrication method of the flexible functional device in this embodiment are basically the same as those of experimental device 1, except that the silk fibroin is replaced with an amino-modified polystyrene DMF solution and a blade coating process is used when fabricating the water-based film. The device in this embodiment has an open-circuit voltage of 0.2V at 28% humidity and 28°C, and its response range to different concentrations of sodium chloride solution is 500μM to 5mM.

[0115] Comparative Example 1

[0116] The structure and fabrication method of the flexible functional device in this embodiment are basically the same as those of experimental device 1, except that the concentration of silk fibroin is 10.5 wt% when fabricating the water-based film. The open-circuit voltage of this comparative device is 0V under conditions of 28% humidity and 28°C. It does not respond to sodium chloride solutions of different concentrations.

[0117] Comparative Example 2

[0118] The structure and fabrication method of the flexible functional device in this embodiment are basically the same as those of experimental device 1, except that the concentration of the silk fibroin solution is 0.0008 wt% when fabricating the water-based film. The open-circuit voltage of the device in this comparative example is 1 V under a humidity of 28% and a temperature of 28°C, and the response range for sodium chloride solutions of different concentrations is 500 μM to 5 mM.

[0119] The water-voltaic thin film based on electrospinning technology provided by this invention features simple processing, ease of implementation, flexibility, lightweight, low cost, and easily controllable structure. For example, the thickness of the water-voltaic thin film can be adjusted by controlling the electrospinning time, the thickness of the electrospinned nanofibers can be adjusted by controlling the concentration of the electrospinning solution, and the thickness of the electrospinned nanofibers and the loading of functionalized polymer materials can be adjusted by adjusting the number of modification times, thereby controlling the open-circuit voltage of the water-voltaic thin film. This allows the water-voltaic thin film to achieve a voltage output higher than 5V, far exceeding that of similar water-voltaic generators. As a clean energy source with continuous, stable power supply and few external limitations, it has wide applications in powering wearable electronic / electrical devices. For example, the ultra-tough water-voltaic thin film provided by this invention can be used to construct a power supply system through series and parallel circuit designs, providing continuous power to wearable electronic devices in different environments.

[0120] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A flexible and tough hydrophobic film, characterized in that, The water-based thin film has a porosity of 50%~90% and a thickness of 100 nm~500 μm, and comprises: The nanofiber framework is an electrospun nanofiber membrane formed by interlacing organic nanofibers with a diameter of 10 nm to 10 μm and has a three-dimensional network structure. The pores contained therein have a pore size of 10 nm to 800 nm. The organic nanofibers are made of nylon 66. And, a functionalized polymeric material in a content of 1 wt% to 30 wt%, wherein the functionalized polymeric material is silk fibroin; The functionalized polymer material is distributed inside and on the surface of the nanofiber skeleton, and exhibits a morphology of adhering, binding and partially encapsulating the organic nanofibers, thereby connecting at least some of the organic nanofibers to each other without blocking the nanoscale channels within the three-dimensional network structure.

2. The flexible and tough hydrothermal film according to claim 1, characterized in that: The organic nanofibers have a diameter of 10 nm to 2 mm.

3. The flexible and tough hydrothermal film according to claim 2, characterized in that: The organic nanofibers have a diameter of 10 nm to 800 nm.

4. The flexible and tough hydrothermal film according to claim 1, characterized in that: The content of the functionalized polymer material in the water-based film is 10 wt% to 20 wt%.

5. The flexible and tough hydrothermal film according to claim 1, characterized in that: The thickness of the water-based film is 1 μm to 80 μm.

6. The flexible and tough hydrothermal film according to claim 1, characterized in that: The width of the water-based film is 0.1~7.5 cm.

7. The flexible and tough hydrothermal film according to claim 1, characterized in that: The water-based thin film contains multiple nanoscale channels with diameters ranging from 10 nm to 2000 nm.

8. The flexible and tough hydrothermal film according to claim 7, characterized in that: The diameter of the nanoscale channel is 10 nm to 800 nm.

9. The use of the flexible and tough hydrovoltaic thin film according to any one of claims 1-8 in the preparation of hydrovoltaic power generation equipment or ion detection equipment.

10. The use according to claim 9, characterized in that: The photovoltaic power generation equipment or ion detection equipment is a flexible device; and / or, the photovoltaic power generation equipment or ion detection equipment is a wearable device.

11. A flexible functional device, characterized in that, Includes the flexible and tough hydrothermal film as described in any one of claims 1-8.

12. The flexible functional device according to claim 11, characterized in that: The flexible functional device further includes a first electrode and a second electrode, which are spaced apart and electrically connected to the water-voltaic thin film, respectively.

13. The flexible functional device according to claim 12, characterized in that: The first electrode and the second electrode are respectively connected to the first end and the second end of the water-based thin film, with the first end and the second end being arranged opposite to each other.

14. The flexible functional device according to claim 13, characterized in that: The distance between the first electrode and the second electrode in a specified direction is 0.2-4.2 cm, and the specified direction is the direction from the first end to the second end.

15. The flexible functional device according to claim 12, characterized in that: The materials of the first electrode and the second electrode include at least one of platinum, gold, carbon black, carbon nanotubes, graphene, ITO glass, FTO glass, and carbon cloth.

16. The flexible functional device according to claim 11, characterized in that: The flexible functional device includes a hydroelectric power generation device or an ion sensor device.

17. The method for preparing a flexible and tough hydrophobic thin film according to any one of claims 1-8, characterized in that, include: S1. Provide a precursor solution of organic nanofibers with a concentration of 1 wt% to 30 wt%, and use the precursor solution as a spinning solution for electrospinning to obtain an electrospun nanofiber membrane as a nanofiber skeleton. S2. At least one of the following methods is used to contact the functionalized polymer material with the electrospun nanofiber membrane, and a portion of the functionalized polymer material enters the electrospun nanofiber membrane to connect at least a portion of the organic nanofibers to each other. S3. The composite fiber membrane obtained in step S2 is dried at 50℃~200℃.

18. The preparation method according to claim 17, characterized in that: The precursor solution comprises an organic material and an organic solvent. The organic material is nylon 66, and the organic solvent comprises any one or a combination of two or more of methanol, ethanol, formic acid, acetic acid, cyclohexane, tetrahydrofuran, dichloromethane, epoxy resin, N,N dimethylformamide, and acetone.

19. The preparation method according to claim 17, characterized in that: The concentration of the precursor solution is 5 wt% to 25 wt%.

20. The preparation method according to claim 17, characterized in that, The electrospinning process parameters include: spinning voltage of 3~50 kV, spinning flow rate of 0.1~5 mL / h, spinning distance of 1cm~20 cm, spinning time of 1h~20 h, receiving roller speed of 50rpm~6000 rpm, ambient temperature of 20℃~30℃, and humidity of 20%~80%.

21. The preparation method according to claim 17, characterized in that: Repeat steps S2-S3 more than twice.

22. A method for generating electricity using hydroelectric power, characterized in that, include: Provide a flexible functional device according to any one of claims 11-16; The first end of the water-voltaic film in the flexible functional device is brought into contact with water, an aqueous solution, or water vapor, thereby generating electricity from the flexible functional device.

23. An ion detection method, characterized in that, include: Provide a flexible functional device according to any one of claims 11-16; By bringing the aqueous phase system containing ions into contact with the first end of the water-voltaic thin film in the flexible functional device, at least the type and / or concentration of ions in the aqueous phase system can be detected.

24. A wearable device, characterized in that, Includes the flexible functional device according to any one of claims 11-16.

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