Universal method for preparing water vapor response type LPL intelligent thin film

Abstract

The invention discloses a general method for preparing a water vapor response type LPL intelligent film, which comprises the following steps: performing electrostatic spinning on a spinning solution at room temperature to obtain the water vapor response type LPL intelligent film, the spinning solution comprising a host material, a guest material and a non-aqueous solvent; the main body material comprises polyvinylpyrrolidone and polyethylene glycol, and the mass part 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-biphenyl diamine and N, N'-diphenyl-2-naphthylamine, and the guest material is at least one of N, N-diphenyl-N, N-di (naphthyl-1)-4, 4-biphenyl diamine and N, N '-diphenyl-2-naphthylamine; the water vapor response type LPL intelligent thin film disclosed by the invention is stimulated by water vapor to start the LPL characteristic. The preparation method has the advantages of simplicity in preparation, environmental friendliness and function integration, and a new solution is provided for intelligent sensing, criminal investigation evidence obtaining, flexible optoelectronic devices and information encryption.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic long afterglow materials, and specifically relates to a general method for preparing a water vapor responsive LPL smart film. Background Art

[0002] In recent years, the doping of organic small molecules into polymer matrices has become an important development direction in the research of organic long-lasting luminescence materials (OLPLMs) due to their excellent photophysical controllable properties and flexible processing characteristics. Although existing research has conducted in-depth exploration of light, heat, and chemical stimuli, the response mechanism of water vapor, a green, accessible, and safe environmental trigger, is still lacking. In particular, water vapor-responsive LPL materials that can simultaneously achieve LPL performance and control material transparency and obtain multifunctionality have not been fully developed.

[0003] At present, the development of water vapor-responsive LPL materials faces two main challenges: on the one hand, traditional humidity-responsive materials (such as inorganic phosphors or metal-organic frameworks) often have problems such as complex synthesis, low response efficiency or poor environmental adaptability, which limit their practical application; on the other hand, although some organic-polymer composite systems have good processability, most materials find it difficult to simultaneously achieve high transparency conversion and accurate reproduction of microscopic morphology during the water vapor response process. Their potential in high-resolution sensing fields such as fingerprint recognition and microtrace detection has not yet been fully explored.

[0004] Therefore, there is an urgent need to seek a new and universal method to prepare water vapor-responsive LPL smart films, develop multi-functional coupling, realize afterglow activation and dynamic regulation of transparency, and at the same time have rubbing capabilities to provide new solutions for the application of LPL materials. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for preparing a water vapor responsive LPL smart film.

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

[0007] Another object of the present invention is to provide an application of the above-mentioned water vapor responsive LPL smart film in texture rubbing.

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

[0009] The purpose of the present invention is achieved through the following technical solutions.

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

[0011] The main material comprises: polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG), and the ratio of polyvinyl pyrrolidone (PVP) to polyethylene glycol (PEG) is (1-3):1 by weight;

[0012] 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-diphenyldiamine (NPD), and N,N'-diphenyl-2-naphthylamine (DBNPD);

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

[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, stirring at 30-60° C. for 8-12 hours until uniform, to obtain the spinning solution.

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

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

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

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

[0019] A water vapor-responsive LPL smart film comprises: a host material and a guest material, wherein the host material is formed into a film having microporous channels in the form of nanofibers, and the guest material is located within the nanofibers. When the water vapor-responsive LPL smart film contacts 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 comprises: polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG), and the ratio of polyvinyl pyrrolidone (PVP) to polyethylene glycol (PEG) is (1-3):1 by mass. 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-diphenylenediamine (NPD), and N,N'-diphenyl-2-naphthylamine (DBNPD).

[0020] Application of the above-mentioned water vapor responsive LPL smart film in skin texture rubbing.

[0021] In the above technical solution, the water vapor-responsive LPL smart film is placed on the surface of the skin to be printed. 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 properties and long afterglow properties, and the luminous intensity of the raised parts of the surface texture of the skin to be printed on the water vapor-responsive LPL smart film is weaker than that of other parts.

[0022] The water vapor responsive LPL smart film is used in detecting water vapor. When the water vapor responsive LPL smart film is stimulated by water vapor, the water vapor responsive LPL smart film exhibits long afterglow performance.

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

[0024] First, the interior of the water vapor-responsive LPL smart film, obtained by electrospinning, consists of a nanofiber structure with numerous microporous channels. The dry water vapor-responsive LPL smart film is then placed in a water vapor environment for water vapor stimulation. As the water vapor stimulation lasts longer, the nanofiber structure gradually dissolves and fuses together, ultimately forming a dense, continuous planar film. During this process, PVP and PEG work synergistically through intermolecular hydrogen bonds, securing the guest material within the rigid framework formed by the two molecules. This effectively suppresses non-radiative energy dissipation, thereby "turning on" the LPL.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. Traditional water vapor-responsive materials (such as inorganic phosphors or metal-organic frameworks) often have complex synthesis issues that limit their practical applications. The method of the present invention is simple and can use water molecules to promote crosslinking between polymer chains, allowing the water vapor-responsive LPL smart film to form a denser crosslinked network. This effectively suppresses the non-radiative transitions of the guest material, thereby enhancing the film's afterglow performance and realizing the water vapor-responsive "LPL" characteristic.

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

[0028] 3. The unique fiber network structure endows the water vapor-responsive LPL smart film with excellent rubbing properties, enabling it to accurately replicate the surface textures of fingers and skin. This water vapor-responsive LPL smart film can be used in precision applications such as rubbing skin texture and fingerprints. Compared to existing technologies, this invention eliminates complex chemical modification processes and instead produces the water vapor-responsive LPL smart film through physical doping and electrospinning. This approach combines ease of preparation, environmental friendliness, and functional integration, offering new solutions for intelligent sensing, criminal investigation and evidence collection, flexible optoelectronic devices, and information encryption. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1( a ) is a schematic diagram of the process for preparing a water vapor-responsive LPL smart film according to Example 1;

[0030] Figure 1(b) is a schematic diagram showing 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 photos of the water vapor responsive LPL smart film prepared in Examples 1 to 4 before and after excitation;

[0033] Figure 3 The semi-logarithmic graphs of the emission decay curves of the water vapor responsive LPL smart films prepared in Examples 1 to 4;

[0034] Figure 4 The phosphorescence emission spectra of the water vapor responsive LPL smart films prepared in Examples 1 to 4 are shown;

[0035] Figure 5 This is a graph showing the afterglow performance decay lifetime of the water vapor responsive LPL smart film prepared in Examples 1 to 4;

[0036] Figure 6 The scanning electron microscope image and atomic force microscope image of the water vapor responsive LPL smart film prepared in Example 1 are shown, wherein: Figure 6 a~ Figure 6 c is a scanning electron microscope image, Figure 6 d~ Figure 6 f is the atomic force microscope image;

[0037] Figure 7 Schematic diagram of the mechanism by which the LPL characteristics of the water vapor-responsive LPL smart film are "turned on" under water vapor stimulation;

[0038] Figure 8 This is a diagram showing 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 showing the application of the water vapor responsive LPL smart film prepared in Example 1 in fingerprint rubbing;

[0040] Figure 10 This is a diagram showing the application of the water vapor responsive LPL smart film prepared in Example 1 in a respiratory mask. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is 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-diphenylenediamine (NPD) were purchased from San 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-diphenylenediamine 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 = 1300000.

[0044] Polyethylene glycol (PEG) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS: 25322-68-3, product 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: Huizhi electrospinning modular spinning equipment HZ-01 produced by Qingdao Nuokang Environmental Protection Technology Co., Ltd.

[0049] Room temperature: 20~25℃.

[0050] The power of the UV lamp in the following examples is 20W.

[0051] The human body exhales towards the surface of the water vapor responsive LPL smart film for 5 to 30 seconds to give the water vapor responsive LPL smart film water vapor stimulation. Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 In the test, the water vapor responsive LPL smart film surface was exhaled for 30 seconds (the relative humidity was 70%). Figure 6 In the test, breath was exhaled onto the surface of the water vapor responsive LPL smart film for 5 seconds or 30 seconds.

[0052] Examples 1 to 4

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

[0054] The spinning solution includes: a main material, a guest material and a non-aqueous solvent, wherein the main material is a mixture of polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG), the non-aqueous solvent is N,N-dimethylformamide (DMF), and the guest material is X;

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

[0056] The method for obtaining the above spinning solution includes: adding polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG) and a guest material to a non-aqueous solvent, stirring at 50° C. for T2 h until uniform, to obtain a 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 of preparing a water vapor-responsive LPL smart film in Example 1. The water vapor-responsive LPL smart film that is not stimulated by water vapor (the "electrospinning film" in Figure 1(a)) has no LPL performance (i.e., no long afterglow luminescence performance).

[0061] Experiments have shown that when the relative humidity reaches 70% or above, the LPL performance of the water vapor responsive LPL smart film of the present invention can be turned on. As shown in Figure 1(b), the water vapor responsive LPL smart film without LPL performance is stimulated by water vapor, so that the LPL performance of the water vapor responsive LPL smart film is turned on. Figure 7 Further explanation: Figure 7 Figure 2 shows a partially enlarged schematic diagram of an "electrospinning film" without LPL performance and a partially enlarged schematic diagram of a "film after water vapor stimulation". First, during the electrospinning process, the rapid volatilization of the non-aqueous solvent results in only loose physical contact between the host material and the guest material, and the guest material fails to integrate into the rigid framework provided by the host material. This ineffective doping state cannot provide the guest material with the rigid environment required to achieve LPL performance. When the water vapor-responsive LPL smart film is exposed to a water vapor environment, water molecules quickly penetrate and diffuse through the porous fiber network, causing the host material (PVP and PEG) to undergo a dissolution-reconstruction process. Figure 7 The enlarged schematic diagram in the middle clearly demonstrates the significant increase in fiber density within 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 water vapor stimulation, the guest material is effectively anchored within the rigid framework of the host material, suppressing non-radiative energy dissipation and thus "activating" the LPL performance.

[0062] As shown in FIG1(c), the water vapor-responsive LPL smart film prepared in Example 1 is white and opaque in a dry state, and its appearance is shown in the “dry state” in FIG1(c). It is excited with a 365 nm ultraviolet lamp for 5 seconds. No long afterglow characteristic is exhibited in the first second after the ultraviolet lamp is turned off (“excitation off” in FIG1(c)), indicating that the LPL performance is turned off at this time. After water vapor stimulation, the water vapor-responsive LPL smart film prepared in Example 1 undergoes a transparent transition induced by moisture absorption. Its appearance is shown in the “wet state” in FIG1(c), indicating that it is a transparent film at this time. The transparent film in the “wet state” is irradiated with a 365 nm ultraviolet lamp for 5 seconds, and the ultraviolet lamp is turned off. The appearance in the first second after the ultraviolet lamp is turned off is shown in the “excitation off” in FIG1(c). At this time, the water vapor-responsive LPL smart film exhibits a long afterglow characteristic, indicating that the LPL performance is successfully activated.

[0063] The water vapor responsive LPL smart film was stimulated by human body exhaling onto its surface for 30 seconds, and then irradiated with 365nm UV light for 5 seconds. The UV light was turned off, and the appearance of the film at 0s, 1s, 2s, 3s, 4s, 5s and 6s after the UV light was turned off was recorded. Figure 2 The photographs shown above were taken after excitation with a 365nm light source. A high-speed camera system was used to record the film's afterglow decay process at 60 fps after the UV light was turned off to accurately determine the afterglow duration. The film was one of the water vapor-responsive LPL smart films prepared in Examples 1-4. Frame analysis revealed that the afterglow durations 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, with the water vapor-responsive LPL smart film exhibiting superior afterglow performance when the guest molecule was 2,2'-dinaphthylamine (Cdp) or N-phenyl-2-naphthylamine (PNA). Figure 2 The following also shows the photos of the water vapor responsive LPL smart film prepared in Examples 1 to 4 before excitation with a 365 nm light source (before and after water vapor stimulation). Figure 2 In the photos corresponding to the “dry state” and “water vapor stimulation”, the transparency of the water vapor responsive LPL smart films prepared in Examples 1 to 4 was improved after water vapor stimulation.

[0064] The film after water vapor stimulation was irradiated with a 365 nm UV lamp for 2 s, and then the UV lamp was turned off. The emission intensity of the film in the light excitation stage and the afterglow stage was collected by a USB 4000 spectrometer from Ocean Optics, USA. Figure 3 The semi-logarithmic graph of the emission decay curve shown is a film among the water vapor responsive LPL smart films prepared in Examples 1 to 4. Figure 3-2~0s is the photoexcitation stage, 0~6s is the UV lamp off stage (afterglow stage), Figure 3 It was found that the film exhibited typical photoluminescence behavior (PL ON) in the light excitation stage, and showed obvious LPL decay characteristics (LPL OFF) in the afterglow stage. Figure 3 The afterglow time corresponding to the water vapor responsive LPL smart film prepared in Examples 1 to 4 is in good agreement with the afterglow time calculated by frame analysis.

[0065] The fluorescence spectrophotometer was used to obtain the 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 Here, "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 significant phosphorescence signal was detected in the water vapor-responsive LPL smart films prepared in Examples 1-4. However, after water vapor stimulation, the phosphorescence intensities of the water vapor-responsive LPL smart films prepared in Examples 1-4 were significantly increased compared to their unstimulated counterparts. The water vapor-responsive LPL smart film prepared in Example 1 showed the most significant increase in phosphorescence intensity after water vapor stimulation. This demonstrates that water molecules induce the host and guest materials to form an efficient LPL doping structure, effectively improving afterglow performance. The maximum emission wavelengths of the water vapor-responsive LPL smart films prepared in Examples 1-4 are distributed in the 500-550nm range.

[0067] The film was tested by Edinburgh FLS1000 photoluminescence spectrometer after water vapor stimulation, and the following results were obtained: Figure 5 The afterglow performance decay life graph shown is a water vapor responsive LPL smart film prepared in Examples 1 to 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. The afterglow performance decay lifetime diagram is fitted by a double / multi-exponential decay model to obtain the delayed emission lifetime of the water vapor-responsive LPL smart films prepared in Examples 1 to 4 (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 (about 36.8%) of the initial intensity after the excitation is stopped). The delayed emission lifetimes of the water vapor-responsive LPL smart films prepared in Examples 1 to 4 are 254ms, 13.1ms, 187ms and 52.2ms, respectively.

[0068] Figure 6 The microscopic morphology of the water vapor responsive LPL smart film prepared in Example 1 under different water vapor stimulation times, wherein: Figure 6 a~ Figure 6 c is the scanning electron microscope (SEM), Figure 6 d~ Figure 6 The f is the atomic force microscope image (AFM). Figure 6 It can be seen from a that the water vapor responsive LPL smart film prepared in Example 1 after drying (without water vapor stimulation) has clearly separated nanofibers. Figure 6 As can be seen from b, when the human body exhales onto the surface of the water vapor responsive LPL smart film for 5s, the nanofibers dissolve and adhere. Figure 6 As can be seen from c, as the water vapor stimulation time increases (exhalation 30s), 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 can be seen from the f, after water vapor stimulation, the surface height difference of the water vapor-responsive LPL smart film prepared in Example 1 decreases from 3.2 microns to 1.8 nanometers as the water vapor stimulation time increases, the surface roughness is significantly reduced, and the surface morphology uniformity is significantly improved. This confirms that water molecule penetration triggers the rearrangement of polymer chains, showing a clear trend of structural densification. SEM and AFM together provide direct morphological evidence for the densification rearrangement of polymer chains, confirming the evolutionary mechanism of water molecule penetration-induced structural densification.

[0069] Example 5

[0070] By utilizing the wettability of the skin surface, the water vapor responsive LPL smart film prepared in Example 1 is tightly attached to the skin of the hand. Figure 8As shown in a, after 2 hours of attachment, the water vapor responsive LPL smart film is peeled off to obtain the first transparent patch. Within 2 hours of attachment, as the contact time increases, the water vapor responsive LPL smart film is converted into a transparent patch (the time of conversion into a transparent patch is affected by the sweating of the hand skin). The first transparent patch is irradiated with a 365nm ultraviolet lamp for 5 seconds, and the ultraviolet lamp is turned off. The appearance of the first transparent patch when the ultraviolet lamp is not irradiated is ( Figure 8 b "before UV excitation"), the appearance of the first transparent patch when irradiated with ultraviolet light ( Figure 8 b) and the appearance of the first transparent patch at 1 second after turning off the UV light ( Figure 8 b) as in "after UV excitation" Figure 8 As shown in b, the water vapor responsive LPL smart film prepared in Example 1 is attached to the skin of the hand to form a transparent patch, and then excited by UV to clearly show the skin microtexture.

[0071] The dried water vapor responsive LPL smart film prepared in Example 1 was wrapped around the fingertips. After 1 minute, the water vapor responsive LPL smart film was transformed into a transparent patch, which was peeled off to obtain a second transparent patch. The second transparent patch was irradiated with a 365nm ultraviolet lamp for 5 seconds, and the ultraviolet lamp was turned off. The appearance of the second transparent patch when not irradiated by the ultraviolet lamp was ( Figure 9 "Before UV excitation"), the appearance of the second transparent patch when irradiated with ultraviolet light ( Figure 9 The appearance of the second transparent patch when 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 and achieve high-fidelity rubbing.

[0072] Example 6

[0073] like Figure 10 As shown, the water vapor responsive LPL smart film prepared in Example 1 is dried and wrapped around the interface between the gas pipe of the breathing mask and the external ventilation valve ( Figure 10 When a user wears the breathing mask, the exhaled gas contacts 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 transparency ( Figure 10 Use 365nm UV light to irradiate the part of the breathing mask wrapped with the water vapor responsive LPL smart film for 5 seconds, turn off the UV light, and the appearance of the mask under UV light irradiation ( Figure 10 "UV excitation") and the appearance of the first second after turning off the UV lamp ( Figure 10 "After UV excitation") Figure 10As shown by Figure 10 It can be seen that water vapor can activate the long-lasting luminescence 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 can be distinguished whether the breathing mask has been used: when it emits long-lasting luminescence when irradiated with ultraviolet light, the mask has been used; when it does not emit long-lasting luminescence when irradiated with ultraviolet light, the mask has not been used.

[0074] The above is an exemplary description of the present invention. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by other skilled in the art without expending creative labor falls within the scope of protection of the present invention.

Claims

1. A method for preparing a water vapor responsive LPL smart film, characterized in that: include: Electrospinning a spinning solution 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; The main material comprises: polyvinyl pyrrolidone and polyethylene glycol, and the ratio of polyvinyl pyrrolidone to polyethylene glycol is (1-3):1 by weight; 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-diphenyldiamine and N,N'-diphenyl-2-naphthylamine; The ratio of polyvinyl pyrrolidone to the guest material is 0.6818:(0.0039-0.0106) by mass.

2. The method according to claim 1, characterized in that The ratio of the mass fraction of the polyvinyl pyrrolidone to the volume fraction of the non-aqueous solvent is 0.6818:(4-7), the unit of the mass fraction is g, and the unit of the volume fraction is mL.

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

4. The method according to claim 1, wherein The voltage of electrospinning is 18-20 kV, and the time of electrospinning is 8-10 h.

5. The method according to claim 1, wherein The propulsion speed of the syringe during the electrospinning process was 0.3-0.6 mL / h.

6. The method according to claim 1, characterized in that The method for obtaining the spinning solution comprises: mixing a main material, a guest material and a non-aqueous solvent, stirring at 30-60° C. for 8-12 hours until the mixture is uniform, and obtaining the spinning solution.

7. A water vapor responsive LPL smart film, characterized in that: include: The invention relates to a host material and a guest material, wherein 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 contacts 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 comprises polyvinyl pyrrolidone and polyethylene glycol, and the ratio of polyvinyl pyrrolidone to polyethylene glycol is (1 to 3):1 by mass. 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-diphenylenediamine and N,N'-diphenyl-2-naphthylamine.

8. Application of the water vapor responsive LPL smart film as claimed in claim 7 in skin texture rubbing.

9. The use according to claim 8, characterized in that The water vapor-responsive LPL smart film is placed on the surface of the skin to be printed. 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, and the luminous intensity of the raised parts of the surface texture of the skin to be printed on the water vapor-responsive LPL smart film is weaker than that of other parts.

10. Application of the water vapor responsive LPL smart film in water vapor detection according to claim 7, characterized in that: When the water vapor responsive LPL smart film is stimulated by water vapor, the water vapor responsive LPL smart film exhibits long afterglow performance.

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