A general method for preparing water vapor responsive LPL smart film

Abstract

The application discloses a general method for preparing a water-vapor-responsive LPL intelligent film, and comprises the following steps: electrospinning a spinning solution at room temperature to obtain a water-vapor-responsive LPL intelligent film, wherein the spinning solution comprises a host material, a guest material and a non-water solvent; the host material comprises polyvinylpyrrolidone and polyethylene glycol, and the mass ratio of the polyvinylpyrrolidone to the polyethylene glycol is (1-3) : 1; the guest material is at least one of 2,2'-dinaphthylamine, N-phenyl-2-naphthylamine, N,N-diphenyl-N,N-di(naphthyl-1)-4,4-biphenyldiamine and N,N'-diphenyl-2-naphthylamine; the water-vapor-responsive LPL intelligent film of the application can 'open' the LPL characteristics under the stimulation of water vapor; the water-vapor-responsive LPL intelligent film has the advantages of simple preparation, environmental friendliness and functional integration, and provides a new solution for intelligent sensing, criminal investigation and evidence collection, and flexible optoelectronic devices and information encryption.

Description

Technical Field

[0001] This invention belongs to the field of organic long afterglow materials technology, specifically relating to a general method for preparing water vapor responsive LPL smart films. Background Technology

[0002] In recent years, doped systems of small organic molecules and polymer matrices have become an important research direction in organic long afterglow materials (OLPLMs) due to their excellent photophysical modulation properties and flexible processing characteristics. Although existing research has explored light, heat, and chemical stimuli in depth, the response mechanism of water vapor, a green, readily available, and safe environmental triggering factor, still lacks systematic research. In particular, water vapor-responsive LPL materials that achieve LPL performance while controlling material transparency and obtaining multifunctionality have not yet been fully developed.

[0003] Currently, the development of water vapor-responsive LPL materials faces two main challenges: First, traditional humidity-responsive materials (such as inorganic phosphors or metal-organic frameworks) often suffer from problems such as complex synthesis, low response efficiency, or poor environmental adaptability, which limit their practical applications. Second, although some organic-polymer composite systems have good processability, most materials cannot simultaneously achieve high transparency conversion and accurate replication of microstructure during water vapor response, and their potential in high-resolution sensing fields such as fingerprint recognition and micro-trace detection has not yet been fully explored.

[0004] Therefore, there is an urgent need to find a new and universally applicable method to prepare water vapor-responsive LPL smart films, develop multifunctional coupling, realize afterglow activation and dynamic control of transparency, and at the same time have imprinting capabilities, so as to provide new solutions for LPL material applications. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing water vapor-responsive LPL smart films.

[0006] Another object of the present invention is to provide a water vapor-responsive LPL smart film obtained by the above method.

[0007] Another objective of this invention is to provide the application of the above-mentioned water vapor responsive LPL smart film in texture printing.

[0008] Another object of the present invention is to provide the application of the above-mentioned water vapor responsive LPL smart film in the detection of water vapor.

[0009] The objective of this invention is achieved through the following technical solution.

[0010] A method for preparing a water vapor responsive LPL smart film includes: electrospinning a spinning solution at room temperature to obtain a water vapor responsive LPL smart film, wherein the spinning solution includes: a host material, a guest material and a non-aqueous solvent;

[0011] The main materials include: polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG), and the ratio of polyvinylpyrrolidone (PVP) to polyethylene glycol (PEG) by mass parts is (1-3):1;

[0012] The guest material is at least one of 2,2'-dinaphthylamine (Cdp), N-phenyl-2-naphthylamine (PNA), N,N-diphenyl-N,N-bis(naphthyl-1)-4,4-biphenyldiamine (NPD), and N,N'-diphenyl-2-naphthylamine (DBNPD);

[0013] The ratio of polyvinylpyrrolidone (PVP) to the guest material by mass parts is 0.6818:(0.0039 to 0.0106).

[0014] In the above technical solution, the method for obtaining the spinning solution includes: mixing the host material, the guest material and the non-aqueous solvent, and stirring at 30-60°C for 8-12 hours until homogeneous to obtain the spinning solution.

[0015] In the above technical solution, the ratio of the mass fraction of polyvinylpyrrolidone (PVP) to the volume fraction of the non-aqueous solvent is 0.6818:(4-7), where the mass fraction is in g and the volume fraction is in mL.

[0016] In the above technical solution, the non-aqueous solvent is N,N-dimethylformamide (DMF).

[0017] In the above technical solution, the electrospinning voltage is 18-20kV and the electrospinning time is 8-10h.

[0018] In the above technical solution, the injection speed during electrospinning is 0.3 to 0.6 mL / h.

[0019] A water vapor responsive LPL smart film includes: a host material and a guest material. The host material is formed into a film with microporous channels in the form of nanofibers, and the guest material is located within the nanofibers. When the water vapor responsive LPL smart film comes into contact with water vapor, the nanofibers fuse to form a dense and continuous planar film, and the guest material is located within the planar film. The host material includes: polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG), with a mass ratio of PVP to PEG of (1-3):1. The guest material is at least one of 2,2'-dinaphthylamine (Cdp), N-phenyl-2-naphthylamine (PNA), N,N-diphenyl-N,N-di(naphthyl-1)-4,4-biphenyldiamine (NPD), and N,N'-diphenyl-2-naphthylamine (DBNPD).

[0020] The above-mentioned water vapor responsive LPL smart film is used in skin texture imprinting.

[0021] In the above technical solution, the water vapor-responsive LPL smart film is placed on the surface of the skin to be imprinted. After the transparency of the water vapor-responsive LPL smart film increases, the water vapor-responsive LPL smart film is irradiated with an ultraviolet lamp. The water vapor-responsive LPL smart film exhibits fluorescence and long afterglow properties. Moreover, the luminescence intensity of the raised parts of the surface texture of the imprinted skin on the water vapor-responsive LPL smart film is weaker than that of other parts.

[0022] The above-mentioned water vapor responsive LPL smart film is used in the detection of water vapor. When the water vapor responsive LPL smart film is stimulated by water vapor, it exhibits long afterglow performance.

[0023] The mechanism by which the above-mentioned water vapor-responsive LPL smart film "activates" its LPL properties under water vapor stimulation is as follows:

[0024] First, the water vapor-responsive LPL smart film obtained by electrospinning has a nanofiber structure with numerous micropores. When the dried water vapor-responsive LPL smart film is placed in a water vapor environment for stimulation, the nanofiber structure gradually dissolves and fuses with each other over time, ultimately forming a dense and continuous planar film. During this process, PVP and PEG work synergistically through intermolecular hydrogen bonds to fix the guest material within the rigid framework formed by PVP and PEG, effectively suppressing non-radiative energy dissipation and thus enabling the "on" of the LPL.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. Traditional water vapor responsive materials (such as inorganic phosphors or metal-organic frameworks) often suffer from complex synthesis issues, limiting their practical applications. The method of this invention is simple and can utilize water molecules to promote cross-linking between polymer chains, enabling the water vapor responsive LPL smart film to form a denser cross-linked network. This effectively suppresses non-radiative transitions of the guest material, thereby enhancing the afterglow performance of the film and realizing the water vapor responsive activation of the "LPL" characteristic.

[0027] 2. Currently, most long-afterglow materials struggle to simultaneously achieve high transparency during the water vapor response process. The water vapor-responsive LPL smart film prepared in this invention can dynamically control the degree of dissolution and adhesion of nanofibers by adjusting the water vapor stimulation time, thereby achieving dynamic control of transparency.

[0028] 3. The unique fiber network structure endows the water vapor-responsive LPL smart film with excellent imprinting performance, enabling it to accurately replicate the textures of fingers and skin surfaces. The water vapor-responsive LPL smart film can be applied to precision scenarios such as imprinting skin textures and fingerprints. Compared to existing technologies, this invention abandons complex chemical modification processes, and water vapor-responsive LPL smart films can be prepared through physical doping and electrospinning. It combines ease of preparation, environmental friendliness, and functional integration, providing new solutions for intelligent sensing, criminal investigation, flexible optoelectronic devices, and information encryption. Attached Figure Description

[0029] Figure 1(a) is a schematic diagram of the process for preparing water vapor-responsive LPL smart films in Example 1;

[0030] Figure 1(b) is a schematic diagram of the principle of water vapor responsive LPL smart film being stimulated by water vapor;

[0031] Figure 1(c) shows the appearance of the water vapor responsive LPL smart film before and after water vapor stimulation;

[0032] Figure 2 These are photographs of the water vapor-responsive LPL smart films prepared in Examples 1-4 before and after excitation.

[0033] Figure 3 The semi-logarithmic plots of the emission decay curves of the water vapor responsive LPL smart films prepared in Examples 1-4 are shown.

[0034] Figure 4 Phosphorescence emission spectra of the water vapor-responsive LPL smart films prepared in Examples 1-4;

[0035] Figure 5 The afterglow performance degradation lifetime diagrams are shown for the water vapor responsive LPL smart films prepared in Examples 1-4.

[0036] Figure 6 The images shown are scanning electron microscope (SEM) and atomic force microscope (AFM) images of the water vapor-responsive LPL smart thin film prepared in Example 1. Figure 6 a~ Figure 6 c is the scanning electron microscope image. Figure 6 d~ Figure 6 f is an atomic force microscope image;

[0037] Figure 7 A schematic diagram illustrating the mechanism by which a water vapor-responsive LPL smart film "activates" its LPL properties under water vapor stimulation;

[0038] Figure 8 This is a diagram illustrating the application of the water vapor-responsive LPL smart film prepared in Example 1 in a skin patch;

[0039] Figure 9 This is a diagram illustrating the application of the water vapor-responsive LPL smart film prepared in Example 1 in fingerprint printing;

[0040] Figure 10 This is a diagram illustrating the application of the water vapor-responsive LPL smart film prepared in Example 1 in a breathing mask. Detailed Implementation

[0041] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0042] 2,2'-Dinaphthylamine (Cdp), N-phenyl-2-naphthylamine (PNA) and N,N-diphenyl-N,N-di(naphthyl-1)-4,4-biphenyldiamine (NPD) were all purchased from Saen Chemical Technology (Shanghai) Co., Ltd. The CAS number of 2,2'-dinaphthylamine is 532-18-3, the CAS number of N-phenyl-2-naphthylamine is 135-88-6, and the CAS number of N,N-diphenyl-N,N-di(naphthyl-1)-4,4-biphenyldiamine is 123847-85-8.

[0043] N,N'-Diphenyl-2-naphthylamine (DBNPD) was purchased from Tianjin Hezhong Biotechnology Co., Ltd., CAS No. 6940-30-3. Polyvinylpyrrolidone (PVP) was purchased from Shandong Yousuo Chemical Technology Co., Ltd., MW = 1,300,000.

[0044] Polyethylene glycol (PEG) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS: 25322-68-3, item number: P103724.

[0045] N,N-Dimethylformamide (DMF) was purchased from Tianjin Dengke Chemical Reagent Co., Ltd.

[0046] Scanning electron microscope: FlexSEM 1000.

[0047] Atomic force microscope: Bruker Dimension ICON.

[0048] Electrospinning equipment: HZ-01 modular electrospinning equipment manufactured by Qingdao Nuokang Environmental Protection Technology Co., Ltd.

[0049] Room temperature: 20~25℃.

[0050] In the following embodiments, the power of the ultraviolet lamp is 20W.

[0051] The water vapor is stimulated by exhaling air onto the surface of the water vapor-responsive LPL smart membrane for 5–30 seconds. Specifically, as shown in Figure 1(c), Figure 2 , Figure 3 , Figure 4 , Figure 5 In the test, breathing onto the surface of the water vapor-responsive LPL smart film for 30 seconds (at a relative humidity of 70%) resulted in... Figure 6 In the test, breath was exhaled onto the surface of the water vapor-responsive LPL smart film for 5 or 30 seconds.

[0052] Examples 1-4

[0053] A method for preparing a water vapor-responsive LPL smart film includes: drawing a spinning solution at 50°C using a syringe, cooling it to room temperature (20-25°C), performing uniaxial electrospinning on the room temperature spinning solution, and obtaining a water vapor-responsive LPL smart film on a receiving device (flat plate collector). The electrospinning voltage is 20kV, the electrospinning time is T1 h, and the syringe advance speed during the electrospinning process is 0.5mL / h.

[0054] The spinning solution includes: a host material, a guest material, and a non-aqueous solvent. The host material is a mixture of polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG), the non-aqueous solvent is N,N-dimethylformamide (DMF), and the guest material is X.

[0055] The ratio of polyvinylpyrrolidone (PVP) to polyethylene glycol (PEG) by mass parts is 2:1. The ratio of PVP to guest material by mass parts is Y. The ratio of PVP by mass parts to non-aqueous solvent by volume parts is 0.6818:5. The units of mass parts are g, and the units of volume parts are mL.

[0056] The method for obtaining the above spinning solution includes: adding polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) and guest material to a non-aqueous solvent, stirring at 50°C for T2 h until homogeneous, to obtain the spinning solution.

[0057] T1, X, Y and T2 are shown in Table 1.

[0058] Table 1

[0059]

[0060] Figure 1(a) is a schematic diagram of the process for preparing a water vapor responsive LPL smart film in Example 1. The water vapor responsive LPL smart film ("electrospun film" in Figure 1(a)) that is not stimulated by water vapor has no LPL properties (i.e. no long afterglow luminescence properties).

[0061] Experiments have shown that when the relative humidity reaches 70% or higher, the LPL performance of the water vapor-responsive LPL smart film of this invention can be activated. As shown in Figure 1(b), stimulating the water vapor-responsive LPL smart film, which currently lacks LPL performance, with water vapor activates its LPL performance. Figure 7 To further explain, Figure 7 The diagram shows a partially enlarged schematic of an "electrospun film" without LPL performance and a partially enlarged schematic of a "film after water vapor stimulation." Firstly, during electrospinning, the rapid evaporation of the non-aqueous solvent results in only a loose physical contact between the host and guest materials; the guest material fails to integrate into the rigid framework provided by the host material. This ineffective doping state cannot provide the rigid environment required for the guest material to achieve LPL performance. When the water vapor-responsive LPL smart film is exposed to a water vapor environment, water molecules rapidly permeate and diffuse through the porous fiber network, causing a dissolution-reconstruction process in the host materials (PVP and PEG). Figure 7 The magnified schematic clearly shows the significant increase in internal fiber density of the water vapor-responsive LPL smart film during this process. Ultimately, the water vapor-responsive LPL smart film transforms from a porous fiber network into a dense, continuous planar structure. Upon stimulation by water vapor, the guest material is effectively fixed within the rigid framework of the host material, suppressing non-radiative energy dissipation, thereby enabling the "activation" of LPL performance.

[0062] As shown in Figure 1(c), the water vapor-responsive LPL smart film prepared in Example 1 is white and opaque in a dry state, as shown in the "dry state" of Figure 1(c). After being excited with a 365nm UV lamp for 5s, no long afterglow characteristic is observed in the first second after the UV lamp is turned off ("excitation off" in Figure 1(c"), indicating that the LPL performance is off at this time. After being stimulated by water vapor, the water vapor-responsive LPL smart film prepared in Example 1 undergoes a transparent transformation induced by moisture absorption, as shown in the "humid state" of Figure 1(c), indicating that it is a transparent film. After irradiating the transparent film in the "humid state" with a 365nm UV lamp for 5s and turning off the UV lamp, the appearance in the first second after turning off the UV lamp is shown in the "excitation off" of Figure 1(c). At this time, the water vapor-responsive LPL smart film exhibits long afterglow characteristic, indicating that the LPL performance has been successfully activated.

[0063] The membrane was stimulated with water vapor by exhaling breath onto its surface for 30 seconds. It was then irradiated with a 365nm UV lamp for 5 seconds, and the UV lamp was turned off. The membrane's appearance was recorded at 0s, 1s, 2s, 3s, 4s, 5s, and 6s after the UV lamp was turned off. The results are shown below. Figure 2 The image shown is an image of the film after excitation by a 365nm light source. The afterglow emission decay process of the film after the UV lamp was turned off was recorded at 60fps using a high-speed camera system to accurately obtain the afterglow emission time. The film is one of the water vapor-responsive LPL smart films prepared in Examples 1-4. Frame-by-frame analysis revealed that the afterglow times of the water vapor-responsive LPL smart films prepared in Examples 1-4 were 6.0s, 1.5s, 5.8s, and 2.5s, respectively. This indicates a significant structure-activity relationship between afterglow performance and the guest molecule structure. The water vapor-responsive LPL smart film exhibits better afterglow performance when the guest molecule is 2,2'-dinaphthylamine (Cdp) or N-phenyl-2-naphthylamine (PNA). Figure 2 The images also show photographs of the water vapor-responsive LPL smart films prepared in Examples 1-4 before excitation by a 365nm light source (before and after water vapor stimulation), such as... Figure 2 The photos corresponding to "dry state" and "water vapor stimulation" show that the transparency of the water vapor responsive LPL smart films prepared in Examples 1-4 is improved after water vapor stimulation.

[0064] The thin film was irradiated with a 365nm ultraviolet lamp for 2 seconds after being stimulated by water vapor. The ultraviolet lamp was then turned off, and the emission intensity of the thin film during the photoexcitation and afterglow stages was collected using a USB 4000 spectrometer from Marine Optics, Inc., as shown in the figure. Figure 3 The semi-logarithmic plot of the emission attenuation curves shown is one of the water vapor responsive LPL smart films prepared in Examples 1-4. Figure 3The photo-excitation phase lasts from -2 to 0 seconds, and the afterglow phase lasts from 0 to 6 seconds. Figure 3 It was found that the thin film exhibited typical photoluminescence behavior (PL ON) during the photoexcitation stage, while showing obvious LPL decay characteristics (LPL OFF) during the afterglow stage. Figure 3 The afterglow times of the water vapor-responsive LPL smart films prepared in Examples 1-4 show good consistency with the afterglow times calculated by frame analysis.

[0065] The results were obtained using a Hitachi F-7000 fluorescence spectrophotometer (Japan). Figure 4 The phosphorescence emission spectra of the film before and after water vapor stimulation are shown. The film is one of the water vapor responsive LPL smart films prepared in Examples 1 to 4. Figure 4 In this context, "Film-Cdp" represents the water vapor-responsive LPL smart film prepared in Example 1 before water vapor stimulation, "Film-Cdp-Steam" represents the water vapor-responsive LPL smart film prepared in Example 1 after water vapor stimulation, "Film-DBNPD" represents the water vapor-responsive LPL smart film prepared in Example 2 before water vapor stimulation, "Film-DBNPD-Steam" represents the water vapor-responsive LPL smart film prepared in Example 2 after water vapor stimulation, "Film-PNA" represents the water vapor-responsive LPL smart film prepared in Example 3 before water vapor stimulation, "Film-PNA-Steam" represents the water vapor-responsive LPL smart film prepared in Example 3 after water vapor stimulation, "Film-NPD" represents the water vapor-responsive LPL smart film prepared in Example 4 before water vapor stimulation, and "Film-NPD-Steam" represents the water vapor-responsive LPL smart film prepared in Example 4 after water vapor stimulation.

[0066] Depend on Figure 4 It can be concluded that, without water vapor stimulation, no obvious phosphorescence signal was detected in any of the water vapor-responsive LPL smart films prepared in Examples 1-4. After water vapor stimulation, the phosphorescence intensity of the water vapor-responsive LPL smart films prepared in Examples 1-4 was significantly improved compared with that without water vapor stimulation. Among them, the water vapor-responsive LPL smart film prepared in Example 1 showed the most significant increase in phosphorescence intensity after water vapor stimulation. This confirms that water molecules induce the host and guest materials to form a highly efficient LPL doping structure, thereby effectively improving afterglow performance. The maximum emission wavelength of the water vapor-responsive LPL smart films prepared in Examples 1-4 is distributed in the range of 500-550 nm.

[0067] The thin film stimulated by water vapor was tested using an Edinburgh FLS1000 photoluminescence spectrometer to obtain the following results: Figure 5 The afterglow performance degradation lifetime diagram shown is for one of the water vapor responsive LPL smart films prepared in Examples 1-4. Figure 5 It can be seen that the water vapor responsive LPL smart films prepared in Examples 1 to 4 all conform to the exponential decay law. By fitting the afterglow performance decay lifetime diagram using a dual / multi-exponential decay model, the delayed emission lifetime of the water vapor responsive LPL smart films prepared in Examples 1 to 4 was obtained (the delayed emission lifetime is the time required for the luminous intensity of the water vapor responsive LPL smart film to decay to 1 / e (approximately 36.8%) of the initial intensity after excitation is stopped). The delayed emission lifetimes of the water vapor responsive LPL smart films prepared in Examples 1 to 4 are 254 ms, 13.1 ms, 187 ms, and 52.2 ms, respectively.

[0068] Figure 6 The microstructure of the water vapor-responsive LPL smart film prepared in Example 1 under different water vapor stimulation times is shown below. Figure 6 a~ Figure 6 c represents the scanning electron microscope (SEM) image. Figure 6 d~ Figure 6 f is an atomic force microscopy (AFM) image. (From...) Figure 6 As can be seen from a, the water vapor-responsive LPL smart film prepared in Example 1, which was dried (without water vapor stimulation), has clearly discrete nanofibers, composed of... Figure 6 As can be seen from b, when a person exhales air onto the surface of the water vapor-responsive LPL smart film for 5 seconds, the nanofibers dissolve and adhere, resulting in... Figure 6 As shown in c, with the extension of water vapor stimulation time (30s of exhalation), the water vapor-responsive LPL smart film prepared in Example 1 eventually forms a non-porous continuous plane, and the fiber interface disappears. Figure 6 d~ Figure 6 As shown in f, after stimulation with water vapor, the surface height difference of the water vapor-responsive LPL smart film prepared in Example 1 decreased from 3.2 μm to 1.8 nm with increasing stimulation time, resulting in a significant reduction in surface roughness and a marked improvement in surface morphology uniformity. This confirms that water molecule penetration triggers polymer chain rearrangement, exhibiting a clear trend towards structural densification. SEM and AFM together provide direct morphological evidence for the polymer chain densification rearrangement, confirming the evolution mechanism of water molecule penetration-induced structural densification.

[0069] Example 5

[0070] Utilizing the skin's surface moisture, the dried water vapor-responsive LPL smart film prepared in Example 1 is tightly adhered to the skin of the hand, such as... Figure 8As shown in Figure a, the water vapor-responsive LPL smart film was peeled off after 2 hours of application to obtain the first transparent patch. During the 2 hours of application, the water vapor-responsive LPL smart film transformed into a transparent patch with increasing contact time (the time of transformation was affected by the amount of sweat on the hand). The first transparent patch was irradiated with a 365nm UV lamp for 5 seconds, and then the UV lamp was turned off. The appearance of the first transparent patch without UV irradiation is shown below. Figure 8 (b) "before UV excitation"), the appearance of the first transparent patch under UV light irradiation ( Figure 8 (b) under "UV excitation" and the appearance of the first transparent patch 1 second after the UV lamp is turned off ( Figure 8 (b) "after UV excitation" Figure 8 As shown in b, the water vapor-responsive LPL smart film prepared in Example 1 is applied to the skin of the hand to form a transparent patch, and then UV excitation can clearly reveal the skin micro-texture.

[0071] The dried water vapor-responsive LPL smart film prepared in Example 1 was wrapped around a fingertip. After 1 minute, the water vapor-responsive LPL smart film transformed into a transparent patch, which was then peeled off to obtain a second transparent patch. The second transparent patch was irradiated with a 365nm UV lamp for 5 seconds, and then the UV lamp was turned off. The appearance of the second transparent patch without UV irradiation is shown in the image. Figure 9 The appearance of the second transparent patch before UV excitation and under UV light irradiation. Figure 9 The appearance of the second transparent patch under "UV excitation" and 1 second after the UV lamp is turned off ( Figure 9 (After UV excitation) Figure 9 As shown, the water vapor-responsive LPL smart film prepared in Example 1 can clearly present fingerprint features, achieving high-fidelity imprinting.

[0072] Example 6

[0073] like Figure 10 As shown, the dried water vapor-responsive LPL smart film prepared in Example 1 is wound around the interface between the gas channel and the external ventilation valve of the breathing mask. Figure 10 (Image corresponding to "breathing detection") When a user wears this breathing mask, the exhaled air comes into contact with the water vapor-responsive LPL smart film. The water vapor molecules cause the main material of the water vapor-responsive LPL smart film to dissolve and reconstruct, resulting in a jump in its transparency. Figure 10 (Before UV excitation). The breathing mask wrapped with a water vapor-responsive LPL smart film was irradiated with a 365nm UV lamp for 5 seconds. The UV lamp was then turned off. The appearance during UV irradiation is shown below. Figure 10 The appearance of the image under UV excitation and the image at 1 second after the UV lamp is turned off. Figure 10 (After UV excitation) Figure 10As shown, by Figure 10 It is known that water vapor can activate the long afterglow emission of the water vapor-responsive LPL smart film. By utilizing the response characteristics of the water vapor-responsive LPL smart film to water vapor stimulation, it is possible to distinguish whether the breathing mask has been used: if it emits a long afterglow when irradiated with an ultraviolet lamp, the mask has been used; if it does not emit a long afterglow when irradiated with an ultraviolet lamp, the mask has not been used.

[0074] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a water vapor-responsive LPL smart thin film, characterized in that, include: A water vapor-responsive LPL smart film is obtained by uniaxial electrospinning of the spinning solution. The spinning solution includes: host material, guest material and non-aqueous solvent. The main materials include: polyvinylpyrrolidone and polyethylene glycol, and the ratio of polyvinylpyrrolidone to polyethylene glycol by mass is (1~3):1; The guest material is at least one of 2,2'-dinaphthylamine, N-phenyl-2-naphthylamine, N,N-diphenyl-N,N-bis(naphthyl-1)-4,4-biphenyldiamine and N,N'-diphenyl-2-naphthylamine; The ratio of polyvinylpyrrolidone to guest material by mass parts is 0.6818 : (0.0039 ~ 0.0106); the ratio of the mass parts of polyvinylpyrrolidone to the volume parts of non-aqueous solvent is 0.6818 : (4 ~ 7), where mass parts are in g and volume parts are in mL.

2. The method according to claim 1, characterized in that, The non-aqueous solvent is N,N-dimethylformamide.

3. The method according to claim 1, characterized in that, The electrospinning voltage is 18~20 kV, and the electrospinning time is 8~10 h.

4. The method according to claim 1, characterized in that, During electrospinning, the syringe advance speed is 0.3~0.6 mL / h.

5. The method according to claim 1, characterized in that, The method for obtaining spinning solution includes: mixing the host material, the guest material and the non-aqueous solvent, and stirring at 30~60 ℃ for 8~12 h until homogeneous to obtain spinning solution.

6. The water vapor-responsive LPL smart thin film obtained by the method according to any one of claims 1 to 5, characterized in that, include: The system comprises a host material and a guest material. The host material is a nanofiber-formed thin film with microporous channels, and the guest material is located within the nanofibers. When the water vapor-responsive LPL smart film comes into contact with water vapor, the nanofibers gradually dissolve, adhere, and fuse to form a dense, continuous, planar transparent film, with the guest material located within the planar transparent film. The host material includes polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG), with a mass ratio of PPVP to PEG of (1~3):

1. The guest material is at least one of 2,2'-dinaphthylamine, N-phenyl-2-naphthylamine, N,N-diphenyl-N,N-di(naphthyl-1)-4,4-biphenyldiamine, and N,N'-diphenyl-2-naphthylamine. The mass ratio of PPVP to the guest material is 0.6818:(0.0039~0.0106). The mass fraction of PPVP and the volume fraction of the non-aqueous solvent are 0.6818. (4~7), the unit of mass parts is g, and the unit of volume parts is mL.

7. The application of the water vapor responsive LPL smart film as described in claim 6 in skin texture imprinting.

8. The application as described in claim 7, characterized in that, The water vapor-responsive LPL smart film is placed on the surface of the skin to be imprinted. After the transparency of the water vapor-responsive LPL smart film increases, it is irradiated with an ultraviolet lamp. The water vapor-responsive LPL smart film exhibits fluorescence and long afterglow properties, and the luminescence intensity of the raised parts of the surface texture of the imprinted skin on the water vapor-responsive LPL smart film is weaker than that of other parts.

9. The application of the water vapor-responsive LPL smart film as described in claim 6 in the detection of water vapor, characterized in that, When the water vapor-responsive LPL smart film is stimulated by water vapor, it exhibits long afterglow performance.

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