Optical printing LPL flexible film material and preparation method and application thereof

Abstract

The application discloses a kind of light printing LPL flexible film materials and preparation method and application thereof, it is related to organic long afterglow material field, a kind of light printing LPL flexible film material includes by host molecule (MO-DPA, DBT or DMBP) and guest molecule (PNA or NPD) 100:1 mole ratio composition main-guest doped system;The host molecule and guest molecule are compounded by electrospinning technology and polymer matrix (PAN, PVP or SAN), and the LPL flexible film material with light printing characteristic is prepared.This application provides light printing LPL flexible film material, and the steric hindrance effect produced by three-dimensional network structure formed by electrospinning is used, realizes oxygen controllable penetration, and high-precision patterning is realized by oxygen quenching effect under ultraviolet mask irradiation.This application provides light printing LPL flexible film material, and universality is strong, and stability is excellent, and complex pattern can be directly written by fast light printing, and application value in the field of anti-fake and information encryption is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of organic long afterglow materials, specifically to a photo-printable LPL flexible thin film material, its preparation method, and its application. Background Technology

[0002] In recent years, long-afterglow luminescent materials have shown significant commercial and scientific importance. Among them, organic long-afterglow luminescent materials (OLPLMs) have attracted considerable attention in areas such as information encryption and anti-counterfeiting, sensing, and bioimaging. The dramatic increase in demand for electronic products has led to significant advancements in photolithography technology. To produce custom devices that overcome the optical diffraction limit, numerous related technologies have been developed, such as two-photon lithography, near-field lithography, and Dip-Pen nanolithography, to generate patterns on polymer and inorganic surfaces. Simultaneously, researchers have utilized processes such as photobleaching, photopolymerization, and electropolymerization in direct writing to induce photophysical or photochemical changes, thereby generating 2D and 3D patterned structures. In this sense, fabricating simple and customized patterns by directly drawing on thin films could indeed be a low-cost alternative.

[0003] Focusing on OLPLMs, they offer excellent opportunities for low-cost, simple optical patterning. Currently, optical patterning construction primarily utilizes host-guest doping methods, employing polymers as the host matrix to construct OLPLMs, mainly leveraging their photoactivation mechanism. Under UV excitation, the phosphor is excited to the T1 state via intersystem transition (ISC), while... 3 The presence of O2 causes phosphorescence quenching. After continuous exposure to UV irradiation, the polymer film... 3 O2 can be transformed into 1 O2, thus hindering the nonradiative dissipation of the phosphor's triplet state and activating its LPL properties. However, once the polymer film is placed under ambient conditions, the air... 3 O2 will gradually diffuse back into the polymer film after a period of time, requiring the film to be re-excited to maintain afterglow emission. This type of material also has a significant drawback: it requires a good match between the guest material and the host matrix, resulting in poor universality, which greatly limits its development and practical applications.

[0004] Therefore, there is an urgent need to find a new and universally applicable method to prepare thin film materials that can be directly patterned and have good stability, so as to greatly broaden the practical applications of organic long-afterglow luminescent materials. Furthermore, combined with its unique photoprinting effect, the encryption level can be significantly improved. Summary of the Invention

[0005] To overcome the above shortcomings, the present invention aims to provide a photo-printable LPL flexible thin film material, which has strong versatility and excellent stability, and can achieve direct writing of complex patterns through rapid photo-printing.

[0006] Another objective of this invention is to provide a method for preparing a photo-printed LPL flexible thin film material.

[0007] Another objective of this invention is to provide the application of photoprintable LPL flexible film materials in anti-counterfeiting and information encryption.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a photo-printable LPL flexible thin film material, comprising a host-guest doping system consisting of a host molecule and a guest molecule. The host molecule is one of 4-methoxydiphenylamine, dibenzothiophene, or 4,4'-dimethylbiphenyl, and the guest molecule is one of N-phenyl-2-naphthylamine containing a naphthylamine group or N,N-diphenyl-N,N-di(naphthyl-1)-4,4-biphenyldiamine.

[0009] Further optimization resulted in a molar ratio of 100:1 between the host molecule and the guest molecule.

[0010] This invention also provides a method for preparing a photo-printed LPL flexible thin film material, comprising the following steps: S1, Weigh a certain amount of precursor polymer material, host molecule and guest molecule as spinning material, add a certain amount of solvent, dissolve and prepare a precursor solution; S2, use a syringe to extract the precursor solution, install it on an electrospinning device, adjust the spinning parameters, and perform spinning.

[0011] In further optimization, in S1, the precursor polymer material is selected from polyacrylonitrile, polyvinylpyrrolidone, or styrene-acrylonitrile copolymer.

[0012] Further optimization is made in S1, where the mass percentage of polyacrylonitrile in the precursor solution is 10%–12%; or the mass percentage of polyvinylpyrrolidone is 8%–12%; or the mass percentage of styrene-acrylonitrile copolymer is 28%–32%.

[0013] In further optimization, in S1, the host molecule and guest molecule account for 30% to 60% of the total mass of the spinning material.

[0014] Further optimization is achieved by ensuring that all reagents in S1 and S2 have a purity level of analytical grade or higher.

[0015] Further optimization is achieved by setting the spinning parameters in S2 as follows: the stirring temperature of the spinning solution is 50°C, the stirring time is 8–12 h, the spinning speed is 10 rpm, the spinning voltage is 18–20 kV, and the spinning solution push speed is 0.3–0.6 mL / h.

[0016] Applications of photoprinted LPL flexible film materials in anti-counterfeiting and information encryption.

[0017] The mechanism by which the aforementioned LPL flexible thin film material exhibits photoprinting properties is as follows: Traditional host-guest doped long afterglow luminescent (LPL) materials form a stable structure through dense intermolecular packing, effectively blocking oxygen erosion in an air environment and thus maintaining photostability. However, during electrospinning, the polymer matrix and LPL material co-deposit to form a three-dimensional network through solvent evaporation. This three-dimensional network structure creates a steric hindrance effect on the ordered arrangement of host-guest molecules, leading to crystal structure defects. This non-dense composite system allows for controllable oxygen permeation, inducing a photoinduced gradient decay of LPL performance under ultraviolet irradiation, ultimately resulting in spatially selective photoprinting through oxygen quenching.

[0018] The aforementioned LPL flexible film material with photoprinting properties is used in anti-counterfeiting and information encryption applications: When this film material is used as an encryption page in the anti-counterfeiting of special documents, no information is displayed under sunlight, but the encrypted pattern becomes clearly visible after exposure to ultraviolet light and its subsequent shutdown, significantly improving the document's anti-counterfeiting performance. Utilizing the precision characteristics of photoprinting, it can directly produce intricate information such as complex QR codes, providing an innovative solution for high-end anti-counterfeiting needs.

[0019] According to the above technical solution, the beneficial effects of the present invention are: 1. This invention provides a series of LPL materials, using N-phenyl-2-naphthylamine and N,N-diphenyl-N,N-di(naphthyl-1)-4,4-biphenyldiamine as novel naphthylamine guest molecules, and 4-methoxydiphenylamine, dibenzothiophene and 4,4'-dimethylbiphenyl as host molecules, to successfully construct a series of host-guest doping systems.

[0020] 2. This invention prepares LPL flexible thin film materials with photoprinting properties through electrospinning. By rapidly solidifying the polymer matrix (PAN, PVP, or SAN) during electrospinning, the formation of dense crystalline structures in OLPLMs is effectively suppressed, resulting in a flexible thin film material with a nanoscale porous network structure. This structure enables controllable oxygen permeation and, utilizing the photoluminescence quenching effect, achieves high-contrast patterning under ultraviolet light irradiation, overcoming the dependence of traditional host-guest materials on dense structures.

[0021] 3. This invention utilizes ultraviolet light mask irradiation to selectively quench the afterglow of a thin film, enabling the direct writing of complex patterns. This thin film material, integrated as an encryption unit into special documents, achieves a dynamic anti-counterfeiting mechanism of "concealment in sunlight and development in ultraviolet light." Its patterns can be stably maintained for more than 24 hours under environmental conditions and is resistant to harsh environments such as water immersion and high to low temperatures of 0–100℃, significantly improving anti-counterfeiting performance and service life.

[0022] 4. This invention utilizes the precision characteristics of optical printing to meet the direct writing requirements of high-precision information (including but not limited to QR codes), providing a new technical approach for the industrial application of OLPLMs in fields such as information security. Attached Figure Description

[0023] Figure 1 It is the chemical structural formula of the host molecule and the guest molecule; Figure 2 This is a graph showing the afterglow performance of OLPLMs prepared in Example 1; Figure 3 This is a schematic diagram of the fabrication process of the optically printed flexible thin film material prepared in Example 2, as well as a schematic diagram of optical printing. Figure 4 These are optically printed images of the flexible thin film material prepared in Example 2; Figure 5 This is a diagram showing the stability of the flexible thin film material prepared in Example 2 in aqueous, low-temperature, and high-temperature environments; Figure 6 These are photoprinted images of the flexible thin film materials prepared in Examples 3 and 4; Figure 7 This is a schematic diagram of the photolithography mechanism for flexible thin film materials; Figure 8 Example 5 illustrates the application of this thin film material as an encryption unit integrated into a special document. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0025] In the following examples, N-phenyl-2-naphthylamine, N,N-diphenyl-N,N-bis(naphthyl-1)-4,4-biphenyldiamine, 4-methoxydiphenylamine, dibenzothiophene, and 4,4'-dimethylbiphenyl were all purchased from Saen Chemical Technology (Shanghai) Co., Ltd.; polyacrylonitrile (PAN, molecular weight: 250K) was purchased from DuPont, USA; polyvinylpyrrolidone (PVP) was purchased from Shandong Yousuo Chemical Technology Co., Ltd.; styrene-acrylonitrile copolymer (SAN) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; and N,N-dimethylformamide (DMF) was purchased from Tianjin Dengke Chemical Reagent Co., Ltd.

[0026] Example 1 The host-guest doping system, also known as the long afterglow luminescence system, uses 4-methoxydiphenylamine (MO-DPA), dibenzothiophene (DBT), and 4,4'-dimethylbiphenyl (DMBP) as host molecules and N-phenyl-2-naphthylamine (PNA) and N,N-diphenyl-N,N-di(naphthyl-1)-4,4-biphenyldiamine (NPD) as guest molecules to prepare a series of OLPLMs, such as... Figure 1 The diagram shows the chemical structural formulas of the host molecule and the guest molecule.

[0027] 1) Preparation of PNA:MO-DPA doped material: 996.25 mg MO-DPA and 11.00 mg PNA were weighed according to the host-guest molar ratio of 100:1 and dissolved in 30.00 mL dichloromethane solution. The PNA:MO-DPA doped material was obtained by rapid evaporation of the solvent.

[0028] 2) Preparation of other doped systems: Using the same preparation process, by replacing the host molecule: DBT or DMBP with MO-DPA, or replacing the guest molecule: NPD with PNA, five sets of comparative doped materials were obtained: PNA:DBT, PNA:DMBP, NPD:MO-DPA, NPD:DBT and NPD:DMBP. The host-guest molar ratio of each host-guest doped system was 100:1.

[0029] like Figure 2 As shown, the afterglow properties of the six host-guest doped systems differ significantly. Among them, the PNA:MO-DPA system exhibits the best overall performance and is therefore selected as the benchmark material for subsequent research.

[0030] Example 2 Preparation of UA-PAN-1 thin film and photoprinting process.

[0031] Weigh 0.9545 g of polyacrylonitrile (PAN) and dissolve it in 7 mL of DMF solvent to prepare a spinning solution with a concentration of 12%. Add 0.0069 g of PNA and 0.6294 g of MO-DPA (host-guest molar ratio of 100:1) to the spinning solution and stir at 50 °C for 12 h to obtain a homogeneous precursor solution.

[0032] The precursor solution was extracted using a syringe, installed in an electrospinning device, and the spinning voltage was adjusted to 20 kV and the spinning solution push rate was 0.5 mL / h. Spinning was carried out, and UA-PAN-1 film was obtained after 6 h of spinning.

[0033] The obtained UA-PAN-1 film was laid flat on a rigid surface, covered with a black perforated template, and then illuminated under a 365 nm light source to complete the pattern printing.

[0034] like Figures 3 to 5 As shown, Figure 3 The preparation process and printing process of the photo-printed flexible film in Example 2 are shown, and the complete process of the technology is presented intuitively. The mask-assisted exposure technology can achieve high-precision pattern transfer within 30 seconds.

[0035] Figure 4 This section describes the photoprinting effect of the flexible film prepared in Example 2. "Template" refers to a pre-designed mask pattern used to control the area irradiated by ultraviolet light. During photoprinting, the template is placed on the film surface, and ultraviolet light can only irradiate the film through the transparent portion of the template, thus forming a latent image pattern corresponding to the template on the film. "Opticalprinting" refers to the process of writing the pattern onto the film by irradiating it with ultraviolet light. When the ultraviolet light is on, the excited areas of the film emit light, displaying the real-time printing effect. After the ultraviolet light is off, the film continues to emit light due to the long afterglow effect, and the pattern remains visible. "View" is the observation stage. After removing the template, the photoprinting characteristics of the film are dynamically verified by switching the ultraviolet lamp on and off. After the ultraviolet light is off, the pre-printed area immediately displays a high-contrast afterglow pattern, while the unprinted area remains dark, forming a clear information boundary. This fully demonstrates that the film possesses excellent photoprinting performance.

[0036] Figure 5 The stability of the flexible film under different environmental conditions, including aqueous, low-temperature, and high-temperature environments, is demonstrated. In area (a) of the figure, the basic performance in the air environment is compared, showing the normal photoprinting effect. In the water environment, after 24 hours of water immersion, the UA-PAN-1 film still shows a stable pattern display in the "UV on / UV of" graph. This is mainly due to the inherent structural support characteristics of the PAN matrix, indicating that the hydrophobicity and structural stability of the PAN matrix effectively protect the LPL material. Meanwhile, due to its excellent thermal stability, the LPL film in area (b) shows high and low temperature tests. The system maintains a high contrast display of the pattern within a wide temperature range of 0–100℃, demonstrating excellent environmental adaptability.

[0037] Example 3 Preparation of UA-PVP-1 thin film and photoprinting process.

[0038] Weigh 0.9545 g of polyvinylpyrrolidone (PVP) and dissolve it in 7 mL of DMF solvent to prepare a 12% spinning solution. Add 0.0069 g of PNA and 0.6294 g of MO-DPA (host-guest molar ratio 100:1) to the spinning solution and stir at 50 °C for 12 h to obtain a homogeneous precursor solution.

[0039] The precursor solution was extracted using a syringe, installed in an electrospinning device, and the spinning voltage was adjusted to 20 kV and the spinning solution push rate was 0.5 mL / h. Spinning was carried out, and UA-PVP-1 film was obtained after 6 h of spinning.

[0040] The obtained UA-PVP-1 film was laid flat on a rigid surface, covered with a black perforated template, and then illuminated under a 365 nm light source to complete the pattern printing.

[0041] Example 4 Preparation of UA-SAN-1 thin film and photoprinting process.

[0042] 2.9982 g of styrene-acrylonitrile copolymer (SAN) was weighed and dissolved in 7 mL of DMF to prepare a 30% spinning solution. 0.0217 g of PNA and 1.9771 g of MO-DPA (host-guest molar ratio 100:1) were added to the spinning solution and stirred at 50 °C for 12 h to obtain a homogeneous precursor solution.

[0043] The precursor solution was extracted using a syringe, installed in an electrospinning device, and the spinning voltage was adjusted to 20 kV and the spinning solution push rate was 0.5 mL / h. Spinning was carried out, and UA-SAN-1 film was obtained after 6 h of spinning.

[0044] The obtained UA-SAN-1 film was laid flat on a rigid surface, covered with a black perforated template, and then illuminated under a 365 nm light source to complete the pattern printing.

[0045] like Figure 6 As shown, the optical printing images of UA-PVP-1 and UA-SAN-1 films demonstrate that after 1 minute of UV stimulation, both films maintain excellent optical printing performance in the photoresponse characteristic test. Their patterning effect is similar to that of the UA-PAN-1 system, showing that the preparation method has excellent universality. At the same time, through comparative experiments with different polymer matrices, the dominant influence of matrix type on the optical printing mechanism was ruled out, confirming that the optical printing characteristics mainly originate from the mechanism of changes in the dense structure of the host-guest doping system caused by the spinning process.

[0046] like Figure 7 The diagram illustrates the photoprinting mechanism of flexible thin films. Traditional host-guest doped long afterglow luminescent (LPL) materials form a stable structure through dense intermolecular packing, effectively blocking oxygen erosion in the air and maintaining photostability. However, during electrospinning, the polymer matrix and LPL material co-deposit to form a three-dimensional network through solvent evaporation. This three-dimensional network structure creates steric hindrance on the ordered arrangement of host-guest molecules, leading to crystal structure defects. This non-dense composite system allows for controllable oxygen permeation, inducing a photoinduced gradient decay of LPL performance under ultraviolet irradiation, ultimately resulting in spatially selective photoprinting through oxygen quenching.

[0047] Example 5 Figure 8 Example 5 illustrates the application of this film as an encryption unit integrated into a special document. The UA-PAN-1 film material prepared in Example 2 is used in a student card. First, the text "HAUST 2024" and a customized pattern are placed on the film surface. After irradiation with 365 nm ultraviolet light for 30 seconds, the optically printed information is input. The material remains inactive under sunlight, but after ultraviolet light excitation and removal, the encrypted information is dynamically displayed through the afterglow effect, significantly improving the document's anti-counterfeiting performance. Further utilizing the high precision of this optical printing technology, a customized QR code template is placed on the same UA-PAN-1 film material and irradiated with a 365 nm light source for 30 seconds, successfully achieving optical printing of complex QR code patterns.

[0048] This breakthrough not only confirms the superiority of the electrospinning-LPL synergistic method in the field of optical information storage, but also expands the application boundaries of optical printing media from traditional image and text recording to the field of intelligent recognition, opening up a new path for the industrial application of LPL materials in the field of information security.

[0049] The foregoing has shown and described the main features, usage methods, basic principles, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention based on actual circumstances without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A photo-printable LPL flexible thin film material, characterized in that: The thin film material is prepared by electrospinning and includes a host-guest doping system consisting of a host molecule and a guest molecule. The host molecule is one of 4-methoxydiphenylamine, dibenzothiophene, or 4,4'-dimethylbiphenyl, and the guest molecule is one of N-phenyl-2-naphthylamine or N,N-diphenyl-N,N-di(naphthyl-1)-4,4-biphenyldiamine containing a naphthylamine group. The molar ratio of the host molecule to the guest molecule is 100:

1.

2. A method for preparing a photo-printable LPL flexible thin film material, characterized in that: Includes the following steps: S1. Weigh a certain amount of precursor polymer material, host molecule, and guest molecule as spinning material, add a certain amount of solvent, dissolve, and prepare a precursor solution; the host molecule is one of 4-methoxydiphenylamine, dibenzothiophene, or 4,4'-dimethylbiphenyl, and the guest molecule is one of N-phenyl-2-naphthylamine containing a naphthylamine group or N,N-diphenyl-N,N-di(naphthyl-1)-4,4-biphenyldiamine; the molar ratio of the host molecule to the guest molecule is 100:1; S2, use a syringe to extract the precursor solution, install it on an electrospinning device, adjust the spinning parameters, and perform spinning.

3. The method for preparing a photo-printable LPL flexible thin film material according to claim 2, characterized in that: In S1, the precursor polymer material is selected from polyacrylonitrile, polyvinylpyrrolidone, or styrene-acrylonitrile copolymer.

4. The method for preparing a photo-printable LPL flexible thin film material according to claim 3, characterized in that: In S1, the precursor solution contains 10% to 12% polyacrylonitrile by mass; or 8% to 12% polyvinylpyrrolidone by mass; or 28% to 32% styrene-acrylonitrile copolymer by mass.

5. The method for preparing a photo-printable LPL flexible thin film material according to claim 2, characterized in that: In S1, the host molecule and guest molecule account for 30% to 60% of the total mass of the spinning material.

6. The method for preparing a photo-printable LPL flexible thin film material according to claim 2, characterized in that: In S1 and S2, all reagents are of analytical grade or higher purity.

7. The method for preparing a photo-printable LPL flexible thin film material according to claim 2, characterized in that: In S2, the spinning parameters are set as follows: the stirring temperature of the spinning solution is 50℃, the stirring time is 8-12 h, the spinning speed is 10 rpm, the spinning voltage is 18-20 kV, and the spinning solution push speed is 0.3-0.6 mL / h.

8. The application of the optically printed LPL flexible film material as described in claim 1 in anti-counterfeiting and information encryption.

Images