Flexible encapsulation film and preparation method therefor, and flexible electronic device

Abstract

Disclosed in the present application are a flexible encapsulation film and a preparation method therefor, and a flexible electronic device. The flexible encapsulation film has an elastomeric polymer with flexible and rigid chain segments as a substrate and comprises an elastomeric polymer surface and a viscoplastic surface, with hard-phase polar polymer microdomains discretely distributed within the viscoplastic surface. The viscoplastic surface comprises a nonpolar elastomeric polymer viscous molecular network and plastic polar polymer microdomains. The polar polymer microdomains have a good compatibility with the viscous molecular network, which enhances the interfacial interaction to form a defect-free interface, imparting the film with an excellent adhesion capability, and improving the barrier performance against water vapor. Meanwhile, the hard-phase polar polymer microdomains are only distributed on the viscoplastic surface of one side of the film, which ensures the mechanical properties thereof. This enables the film to achieve a strong adhesion to various substrates while maintaining a high stretchability and a superior barrier performance.

Description

Flexible encapsulation films and their preparation methods, flexible electronic devices Technical Field

[0001] This application relates to the field of encapsulation film technology, and in particular to a flexible encapsulation film and its preparation method, and a flexible electronic device. Background Technology

[0002] In flexible electronics technology, the packaging of flexible electronic products currently mostly uses elastomeric sealing materials. These materials are characterized by their ability to deform synchronously with electronic components, thus fully utilizing the flexible functions of the devices. To maintain electrical performance and functional stability under various deformation states, the encapsulation film needs to conformally adhere to various components while possessing both stretchability and high barrier properties. Stretchability ensures that the device will not easily break or be damaged during deformation, continuously providing effective protection and adapting to different application scenarios and complex mechanical environments. High barrier properties effectively block the corrosion of harmful substances such as moisture and oxygen in the external environment, thereby greatly extending the device's lifespan. Currently, ensuring a tight bond between the encapsulation film and electronic devices under different deformation states, while simultaneously improving the high barrier sealing and stretchability of the encapsulation structure, remains a key technical challenge.

[0003] Therefore, developing a flexible packaging film that can be tightly bonded to various flexible electronic device modules while also possessing high stretchability and high barrier properties is of great significance for the packaging of flexible electronic devices.

[0004] Application content

[0005] One of the objectives of this application is to provide a flexible encapsulation film and its preparation method, as well as a flexible electronic device, which aims to solve, to a certain extent, the problems of poor adhesion, poor stretchability, and poor barrier properties of existing encapsulation films and devices.

[0006] The technical solution adopted in the embodiments of this application is:

[0007] In a first aspect, this application provides a flexible encapsulation film, wherein the flexible encapsulation film uses an elastomeric polymer having flexible and rigid segments as a substrate, the flexible encapsulation film includes an elastomeric polymer surface and a viscoplastic surface, wherein polar polymer microdomains of a hard phase are discretely distributed in the viscoplastic surface.

[0008] Secondly, this application provides a method for preparing a flexible encapsulation film, comprising the following steps:

[0009] An elastomeric polymer and a polar polymer are mixed into a slurry; the elastomeric polymer has flexible segments and rigid segments;

[0010] The mixed slurry is deposited on the surface of a substrate and subjected to micro-phase separation treatment, so that the polar polymer forms a hard phase microdomain structure discretely distributed on one side of the film layer surface. After drying, a flexible encapsulation film with an elastomeric polymer surface and a viscoplastic surface is obtained; the polar polymer microdomains are discretely distributed in the viscoplastic surface.

[0011] Thirdly, this application provides a flexible electronic device, which includes the above-described flexible encapsulation film and / or the flexible encapsulation film prepared by the above-described method.

[0012] The flexible encapsulation film provided in the first aspect of this application uses an elastomeric polymer having flexible and rigid segments as a substrate. The flexible encapsulation film has two opposing surfaces: one surface is an elastomeric polymer surface composed of the elastomeric polymer substrate; the other surface is a viscoplastic surface containing a non-polar elastomeric polymer viscous molecular network and plastic hard-phase polar polymer microdomains. On one hand, these polar polymer microdomains are partially compatible with the flexible segments in the elastomeric polymer substrate. During phase separation, the polar polymer microdomains enhance the π-π stacking disorder between the rigid segments, which serve as physical crosslinking points, by adsorbing the flexible segments in the elastomeric polymer, significantly improving the mobility of the bulk elastomeric polymer chains in the surface layer of the flexible encapsulation film. On the other hand, the polar groups in the polar polymer microdomains are highly reactive and readily form chemical bonds with other materials, enhancing the interaction between material interfaces. In the viscoplastic surface layer, the polar polymer microdomains exhibit hard-phase characteristics. This ingenious fusion of soft and hard phases transforms the surface properties of the flexible encapsulation film from traditional elasticity and inertness to novel properties of viscoplasticity and reactivity. Therefore, the high mobility of the elastomeric polymer molecular chains in the viscoplastic surface layer, combined with the microdomains of the hard-phase polar polymer, endows the flexible encapsulation film with excellent adhesion, enabling it to form tight, robust, and stretchable adhesions with various device modules and substrates regardless of size, material properties, or geometry. Simultaneously, the discrete distribution of these polar polymer microdomains effectively increases the diffusion paths of water molecules, enhancing the water vapor barrier performance of the flexible encapsulation film. Furthermore, the hard-phase polar polymer microdomains are distributed only on one side of the viscoplastic surface of the flexible encapsulation film, without altering the overall properties of the film, thus ensuring the maintenance of its mechanical properties. This allows the flexible encapsulation film to not only bond tightly to various flexible electronic device modules and other encapsulation substrates, but also possess high stretchability and high barrier properties.

[0013] The second aspect of this application provides a method for preparing a flexible encapsulation film. After preparing a mixed slurry of an elastomeric polymer and a polar polymer, the mixed slurry is deposited on the surface of a substrate for micro-phase separation. During this micro-phase separation process, the polar polymer forms a hard-phase microdomain structure. The growth of the microdomains is limited by the influence of the elastomeric polymer, maintaining the micro-nano size of the polar polymer microdomains. The formed polar polymer microdomains are slowly deposited to one side of the film layer under the influence of gravity. Simultaneously, during the film drying process, the rising of solvent evaporation prevents the polar polymer microdomains from agglomerating into a film. The doping of polar polymer microdomains gives one surface of the flexible encapsulation film viscoplasticity, forming a viscoplastic surface, while the opposite surface is the elastomeric polymer surface. The polar polymer microdomains have good compatibility with the flexible segments in the elastomeric polymer, which can reduce the π-π stacking between rigid segments in the elastomeric polymer, increase the disorder of the rigid segments, promote molecular structure rearrangement, and form a defect-free interface between the polar polymer microdomains and the elastomeric polymer, significantly improving the polymer chain mobility on the surface of the flexible encapsulation film. Furthermore, the polar groups in the polar polymer microdomains are highly reactive and readily form chemical bonds with other materials, enhancing interfacial interactions and endowing the flexible encapsulation film with excellent adhesion and improved moisture barrier performance. Moreover, the hard-phase polar polymer microdomains are distributed only on one side of the viscous surface of the flexible encapsulation film, without altering the surface properties of the elastomeric polymer or the overall properties of the flexible encapsulation film. This ensures the mechanical properties of the flexible encapsulation film, enabling it to bond tightly to various flexible electronic device modules and other encapsulation substrates while simultaneously possessing high stretchability and high barrier properties.

[0014] The third aspect of this application provides a flexible electronic device comprising the aforementioned flexible encapsulation film. This flexible encapsulation film can not only be tightly bonded to the substrate to be encapsulated for various modules of the flexible electronic device, but also has high stretchability and high barrier properties, effectively bridging the contradiction between adhesion, barrier properties and stretchability in the field of flexible electronic packaging. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or exemplary technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 is a schematic diagram of the structure of the flexible encapsulation film provided in an embodiment of this application;

[0017] Figure 2 is a schematic diagram of the interaction between the elastomeric polymer and the polar polymer in the flexible encapsulation film provided in the embodiments of this application;

[0018] Figure 3 is an observation diagram of the surface microstructure of the flexible encapsulation film before and after the addition of PP-g-MAH in Example 1 of this application using atomic force microscopy (AFM); and a size distribution diagram of polystyrene (PS) nanodomains adjacent to PP-g-MAH microdomains in the surface of the flexible encapsulation film before and after the addition of PP-g-MAH (c and d).

[0019] Figure 4 is a grazing incidence wide-angle X-ray scattering (GIWAXS) spectrum of the flexible encapsulation film provided in Embodiment 1 of this application;

[0020] Figure 5 is a test diagram of the stringing phenomenon on the adhesive surface of the flexible encapsulation film provided in Embodiment 1 of this application;

[0021] Figure 6 is an adhesion test diagram of the viscoplastic surface of the flexible encapsulation film provided in Embodiment 1 of this application to plastic, elastomer and hydrogel;

[0022] Figure 7 is a comparative test diagram of water vapor transmission rate and mechanical modulus of the flexible encapsulation film provided in Embodiment 1 of this application;

[0023] Figure 8 shows test results of surface indentation residue on the viscoplastic surface of the flexible encapsulation film of Example 2 of this application and the elastomeric surface of the encapsulation film of pure elastomeric polymer of Comparative Example 1. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the scope of this application.

[0025] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly or indirectly attached to that other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to that other component. The terms "upper," "lower," "left," "right," etc., indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, and are for ease of description only, not to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. "A plurality" means two or more, unless otherwise explicitly defined.

[0026] In flexible electronics technology, elastomeric sealing materials are currently widely used for packaging flexible electronic products. To maintain electrical performance and functional stability under various deformation conditions, the encapsulation film needs to conformally fit various components while possessing both stretchability and high barrier properties. Currently, ensuring tight adhesion between the encapsulation film and electronic devices under different deformation conditions, while simultaneously improving the high barrier sealing and stretchability of the encapsulation structure, remains a key technical challenge.

[0027] In the field of flexible electronic packaging, water and oxygen permeation caused by packaging is a major cause of device failure. Among these, blocking water vapor is particularly challenging. This is because water molecules are not only small in size but also highly polar, enabling them to interact with various materials and significantly increasing the likelihood of permeation. Traditional packaging materials typically use rigid plastics or resins, although these materials can achieve an intrinsic water vapor permeability of 10⁻⁶. -1 Up to 10 -2 g / m 2 However, this also limits the overall device to bending on a relatively small scale, failing to meet the packaging requirements of some more flexible or even stretchable electronic devices. Therefore, there is an urgent need to explore new packaging materials that combine excellent sealing performance with elastic tensile properties.

[0028] There is a trade-off between the elasticity and barrier properties of polymer materials: materials with good elasticity have weaker intermolecular forces and relatively poorer barrier properties; while materials with tightly packed molecules have higher rigidity and barrier properties. Common elastomer materials, such as silicone rubbers (polydimethylsiloxane PDMS, Ecoflex), are widely used as substrates for various flexible and stretchable devices due to their low modulus and high elasticity. However, the relatively large intermolecular spacing and strong molecular chain polarity of these materials result in a high diffusion coefficient for water molecules, with an intrinsic water vapor permeability reaching 10⁻⁶. 2 g / m 2 / day, therefore, it is not an ideal sealing material. In this regard, elastomers with tightly packed molecular arrangements and nonpolar polymer chains are more ideal encapsulation substrates. However, nonpolar molecular networks cannot bond tightly to the device layer, causing interfacial delamination during the frequent stretching of flexible electronic devices, leading to encapsulation failure. Currently, research on the interfacial adhesion problem of inert molecular networks focuses on enhancing the interfacial interaction by increasing the polarity of the material surface. Common methods include polymer blending modification and surface coating treatment. While these strategies are effective in improving interfacial adhesion strength, they often come at the cost of sacrificing the material's mechanical properties and barrier properties.

[0029] The fluidity and molecular polarity of polymer segments at the interface are crucial factors affecting adhesive strength. Highly fluid polymer segments can more effectively wet the bonded surfaces, increasing the actual contact area and improving adhesive strength; while polar molecules form stronger interfacial interactions by creating chemical bonds with the surfaces of the bonded materials. However, increased polymer segment fluidity and enhanced molecular polarity also promote water molecule diffusion, thereby reducing the material's barrier properties. Therefore, there is an urgent need to develop a flexible encapsulation film that can bond tightly to various flexible electronic device modules while simultaneously possessing high stretchability and high barrier properties.

[0030] The first aspect of this application provides a flexible encapsulation film, as shown in Figure 1. The flexible encapsulation film uses an elastomeric polymer having flexible and rigid segments as a substrate. The flexible encapsulation film includes an elastomeric polymer surface and a viscoplastic surface, in which polar polymer microdomains are discretely distributed.

[0031] The flexible encapsulation film provided in the first aspect of this application uses an elastomeric polymer having flexible and rigid segments as a substrate. The flexible encapsulation film has two opposing surfaces: one surface is an elastomeric polymer surface composed of the elastomeric polymer substrate; the other surface is a viscoplastic surface containing a non-polar elastomeric polymer viscous molecular network and plastic hard-phase polar polymer microdomains. The polar polymer microdomains refer to tiny particles composed of polar polymers, typically ranging in size from a few nanometers to a few micrometers. Polar polymers are a class of polymer materials with special properties; their molecules contain polar bonds or polar groups, giving the entire molecule a certain degree of polarity. In elastomeric polymers, flexible segments, also known as soft segments, have molecular chains that can be coiled and bent to a certain extent, thus exhibiting good flexibility and elasticity. Flexible segments endow polymer materials with good flexibility and processing properties, allowing the polymer to maintain stable properties over a wide temperature range. Rigid segments, also known as hard segments, have relatively fixed structures, and their molecular chains are not easily bent or coiled, thus exhibiting high rigidity and strength. The presence of rigid segments gives the polymer material higher strength and hardness, while also improving its heat resistance and chemical corrosion resistance. In the application of the flexible encapsulation film in this application, the adhesive surface bonds to the substrate to be encapsulated.

[0032] The flexible encapsulation film of this application embodiment has at least the following performance advantages:

[0033] On the one hand, the polymer chains in polar polymer microdomains have a certain degree of compatibility with the flexible segments in the elastomeric polymer, which is beneficial for forming hard-phase microdomains with good interfaces during the separation process from the elastomeric polymer matrix. Furthermore, these polar polymer microdomains can reduce the π-π stacking between rigid segments in the elastomeric polymer, increase the disorder of the rigid segments, and facilitate partial phase separation between the elastomeric polymer matrix. This improves the bonding performance between the polar polymer microdomains and the elastomeric polymer, resulting in a defect-free interface. Simultaneously, the doping of polar polymer microdomains promotes the rearrangement of the molecular structure of the surface layer of the flexible encapsulation film, significantly improving the polymer chain mobility on the surface of the flexible encapsulation film. This effect is illustrated in a schematic diagram in Figure 2.

[0034] On the other hand, the polar groups in polar polymer microdomains are highly reactive and readily form chemical bonds with other materials, enhancing interfacial interactions. The combination of the high mobility of elastomeric polymer molecular chains with polar polymer microdomains endows flexible encapsulation films with excellent adhesion, enabling them to form tight, robust, and stretchable adhesions to various device modules and substrates regardless of size, material properties, or geometry. Furthermore, the polar polymer microdomains in the viscoplastic surface layer exhibit hard-phase characteristics. This ingenious fusion of soft and hard phases transforms the surface properties of flexible encapsulation films from traditional elasticity and inertness to novel properties of viscoplasticity and reactivity. Simultaneously, the discrete distribution of these polar polymer microdomains effectively increases the diffusion paths of water molecules, improving the water vapor barrier performance of the flexible encapsulation film material.

[0035] On the other hand, the polar polymer microdomains of the hard phase are only distributed on the adhesive surface of one side of the flexible packaging film, without changing the overall properties of the flexible packaging film. This ensures that the mechanical properties of the flexible packaging film are maintained, so that the flexible packaging film can be tightly bonded to various flexible electronic device modules and other packaging substrates, while also having high stretchability and high barrier properties.

[0036] In some possible implementations, the doping concentration of polar polymer microdomains increases along the direction from the elastomeric polymer surface towards the viscoplastic surface in the flexible encapsulation film. In this case, the high doping concentration of polar polymer microdomains on the viscoplastic surface ensures the improvement of the surface adhesion and moisture barrier properties of the flexible encapsulation film. The doping concentration decreases closer to the elastomeric polymer surface, and the doping of polar polymer microdomains on the elastomeric polymer surface ensures the maintenance of the mechanical properties of the flexible encapsulation film.

[0037] In some possible implementations, the mass percentage of polar polymer microdomains in the flexible encapsulation film is 2% to 10%. Specifically, it can be any typical but non-limiting point value or a range between any two points, such as 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%. In this case, the polar polymer microdomains can effectively improve the adhesion and moisture barrier properties of the flexible encapsulation film surface, forming a viscoplastic surface that provides sufficient adhesion strength to the substrate to be encapsulated. Simultaneously, it helps maintain the mechanical properties of the flexible encapsulation film, avoiding a reduction in mechanical properties due to excessively high polar polymer microdomain ratios.

[0038] In some possible implementations, the average particle size of the polar polymer microdomains is 50 nm to 2 μm. Specifically, it can be any typical but non-limiting point value or a range between any two points, such as 50 nm, 100 nm, 200 nm, 500 nm, 800 nm, 1000 nm, 1.2 μm, 1.5 μm, 1.8 μm, and 2.0 μm. In this case, the polar polymer microdomains are at the micro-nano scale, which is beneficial for their discrete distribution on the adhesive surface of the flexible encapsulation film. This improves the uniformity of polar polymer microdomain doping, significantly enhances the adhesion and moisture barrier properties of the flexible encapsulation film surface, and prevents microdomain aggregation and sedimentation from affecting the adhesion, barrier properties, and stretch flexibility of the flexible encapsulation film.

[0039] In some possible implementations, the thickness of the flexible encapsulation film ranges from 10 μm to 2 mm. Specifically, it can be any typical but non-limiting point value or a range between any two points, such as 10 μm, 20 μm, 50 μm, 100 μm, 200 μm, 500 μm, 800 μm, 1000 μm, 1.2 mm, 1.5 mm, 1.8 mm, and 2 mm. In this case, the flexible encapsulation film has a wide thickness distribution range, which can meet the encapsulation application requirements of different flexible devices.

[0040] In some possible implementations, the elastomeric polymer includes a styrene block copolymer. This elastomeric polymer exhibits excellent biocompatibility, gas barrier properties, thermo-oxidative stability, and characteristics such as softness and tunable structural properties.

[0041] In some possible implementations, the elastomeric polymer includes at least one of styrene-butadiene-styrene block copolymers (SBS), styrene-isoprene-styrene block copolymers (SIS), styrene-ethylene / butene-styrene block copolymers (SEBS), styrene-ethylene / propylene-styrene block copolymers (SEPS), and styrene-isobutylene-styrene block copolymers (SIBS). Among these elastomeric polymers, styrene-based block copolymers (SBCs) composed of ethylene / propylene / butadiene / isoprene and styrene all possess excellent biocompatibility, gas barrier properties, thermo-oxidative stability, and are characterized by softness and tunable structural properties. In some specific embodiments, the elastomeric polymer includes styrene-isobutylene-styrene block copolymers (SIBS) which have good thermal stability and low water vapor permeability.

[0042] In some possible implementations, the polar polymer microdomains include at least one of maleic anhydride-grafted polymers and glycidyl ether-grafted polymers.

[0043] In some possible implementations, the polar polymer microdomains include at least one of maleic anhydride-grafted polyethylene (PE-g-MAH), maleic anhydride-grafted polypropylene (PP-g-MAH), maleic anhydride-grafted polyolefin elastomer (POE-g-MAH), glycidyl ether-grafted polypropylene (PP-g-GMA), maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer, and glycidyl ether-grafted polypropylene. In some specific embodiments, the polar polymer microdomains include PP-g-MAH.

[0044] In some possible implementations, the selected maleic anhydride-grafted polymer is closely related to its molecular structure. Taking maleic anhydride-grafted polypropylene (PP-g-MAH) as an example, the polypropylene (PP) exhibits good compatibility with the soft block portion of the elastomer polymer, which is beneficial for forming hard phase microdomains with good interfaces during the separation process from the elastomer polymer matrix. Meanwhile, the maleic anhydride group (MAH) is a highly polar reactive group that readily forms chemical bonds with other materials, enhancing the interfacial interactions.

[0045] Secondly, embodiments of this application provide a method for preparing a flexible encapsulation film, comprising the following steps:

[0046] S10. Prepare a mixed slurry from an elastomer polymer and a polar polymer; the elastomer polymer has flexible segments and rigid segments;

[0047] S20. The mixed slurry is deposited on the surface of the substrate and subjected to micro-phase separation treatment, so that the polar polymer forms a hard phase microdomain structure distributed on one side of the film layer surface. After drying, a flexible encapsulation film with an elastomeric polymer surface and a viscoplastic surface is obtained; the polar polymer microdomains are discretely distributed in the viscoplastic surface.

[0048] This application describes a method for preparing a flexible encapsulation film. After preparing a mixed slurry of an elastomeric polymer and a polar polymer, the slurry is deposited on the surface of a substrate for micro-phase separation. During this process, the polar polymer forms a hard-phase microdomain structure. The growth of these microdomains is limited by the influence of the elastomeric polymer, maintaining their micro-nano size. The formed polar polymer microdomains are slowly deposited to one side of the film layer under the influence of gravity. Simultaneously, during the film drying process, the rising solvent evaporation prevents the polar polymer microdomains from agglomerating into a film. The doping of polar polymer microdomains gives one surface of the flexible encapsulation film viscoplasticity, forming a viscoplastic surface, while the opposite surface remains the elastomeric polymer surface. The polar polymer microdomains exhibit good compatibility with the flexible segments in the elastomeric polymer, reducing π-π stacking between rigid segments in the elastomeric polymer, increasing the disorder of the rigid segments, promoting molecular rearrangement, and forming a defect-free interface between the polar polymer microdomains and the elastomeric polymer. This significantly improves the polymer chain mobility on the surface of the flexible encapsulation film. Furthermore, the polar groups in the polar polymer microdomains are highly reactive and readily form chemical bonds with other materials, enhancing interfacial interactions and endowing the flexible encapsulation film with excellent adhesion and improved moisture barrier performance. Moreover, the hard-phase polar polymer microdomains are distributed only on one side of the viscous surface of the flexible encapsulation film, without altering the surface properties of the elastomeric polymer or the overall properties of the flexible encapsulation film. This ensures the mechanical properties of the flexible encapsulation film, enabling it to bond tightly to various flexible electronic device modules and other encapsulation substrates while simultaneously possessing high stretchability and high barrier properties.

[0049] In step S10 above:

[0050] In some possible implementations, the preparation method of the mixed slurry includes a dissolution method or a melt method. In some embodiments, the elastomeric polymer is mixed with a selected polar polymer in a precise mass ratio, and then dissolved using an organic solvent dissolution method or a high-temperature melt method to ensure that the two materials are fully mixed and form a homogeneous solution or melt mixed slurry.

[0051] In some possible implementations, the dissolution method involves preparing solutions of the elastomeric polymer and the polar polymer separately, followed by blending to obtain a mixed slurry. In this case, the elastomeric polymer and the polar polymer are dissolved separately in a solvent before blending to ensure that the two materials are thoroughly mixed and form a homogeneous solution.

[0052] In some possible implementations, the concentration of the elastomeric polymer solution is 50 mg / mL to 500 mg / mL; specifically, it can be any typical but non-limiting point value or an interval between any two point values, such as 50 mg / mL, 100 mg / mL, 150 mg / mL, 200 mg / mL, 250 mg / mL, 300 mg / mL, 350 mg / mL, 400 mg / mL, and 500 mg / mL.

[0053] In some possible implementations, the concentration of the polar polymer solution is 0.5 mg / mL to 25 mg / mL; specifically, it can be any typical but non-limiting point value or an interval between any two point values, such as 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 5 mg / mL, 10 mg / mL, 15 mg / mL, 20 mg / mL, 25 mg / mL.

[0054] In the embodiments described above, the concentrations of the elastomeric polymer solution and the polar polymer solution are sufficiently controlled to ensure uniform mixing of the two polymers, resulting in a mixed slurry with good film-forming properties. Concentrations that are too low or too high can easily lead to numerous defects in the film, which is detrimental to improving the gas barrier properties of the film.

[0055] In some embodiments, the steps for preparing the mixed slurry using an organic solvent dissolution method include: First, selecting a benign organic solvent such as toluene or n-hexane to completely dissolve the elastomer polymer, resulting in a solution with a mass concentration of 50 mg / mL to 500 mg / mL, at a temperature of room temperature to 80°C. Dissolution is aided by a magnetic stirrer or ultrasonic equipment to ensure complete dissolution of the particles. Next, the same benign solvent is used to dissolve the polar polymer, resulting in a solution labeled as the polar polymer solution, with a mass concentration controlled at 0.5 mg / mL to 25 mg / mL, at a temperature of 125°C to 160°C. After complete dissolution, a cold water circulation system is initiated for reflux condensation. At room temperature, the elastomer polymer solution is slowly poured into the polar polymer solution, and ultrasonication or stirring is continued for at least 2 hours to finally obtain a homogeneous blend solution, i.e., the mixed slurry.

[0056] In some possible implementations, the melt method involves: melting an elastomeric polymer with a plasticizer and a viscosity reducer, then adding a polar polymer and melting again to obtain a mixed slurry. The plasticizer is used to increase plasticity, and the viscosity reducer is used to decrease viscosity.

[0057] In some possible implementations, the temperature conditions for the melt method are 140℃ to 200℃; specifically, it can be any typical but non-limiting point value or a range between any two points, such as 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, and 200℃. Under these temperature conditions, the elastomer polymer can be fully melt-mixed with the plasticizer and viscosity reducer.

[0058] In some possible implementations, the mass ratio of the elastomeric polymer to the plasticizer and viscosity reducer is (200–400):(20–100):(2–15). In this case, the ratio of the elastomeric polymer to the plasticizer and viscosity reducer can prepare a mixed slurry with good processing performance and flowability. The plasticizer increases plasticity and adjusts the mechanical modulus of the film; the viscosity reducer increases the viscosity of the mixed slurry and improves its plasticity. This ratio ensures both the preparation of the mixed slurry and its good processing performance and flowability, facilitating the subsequent film formation of flexible encapsulation films.

[0059] For example, the mass ratio of the elastomer polymer to the plasticizer and viscosity reducer can be any typical but non-limiting point value or a range between any two point values, such as 200:20:2, 300:50:10, 400:100:15, 250:30:8, 350:80:12.

[0060] In some possible implementations, the plasticizer comprises a polyisobutylene liquid rubber with an average molecular weight of 400 to 2000. Exemplarily, the average molecular weight of the polyisobutylene liquid rubber can be any typical but not limiting point value or a range between any two points, such as 400, 500, 600, 800, 1000, 1200, 1500, 1800, or 2000. At this molecular weight, the polyisobutylene liquid rubber can better regulate the plasticity of the mixed slurry, thereby improving the mechanical modulus of the flexible encapsulation film.

[0061] In some possible implementations, viscosity reducers include at least one of naphthenic oils, paraffinic oils, and aromatic oils. These materials can all adjust the viscosity and plasticity of the mixed slurry.

[0062] In some embodiments, a high-temperature melting method is used to prepare the mixed slurry: In a reactor, the temperature is gradually increased to 140°C-200°C. During this process, 200-400 grams of an elastomeric polymer, 20-100 grams of a plasticizer such as polyisobutylene liquid rubber with an average molecular weight of 400-2000, and 2-15 grams of a viscosity reducer such as naphthenic oil are added. The stirring device is then started to ensure that the materials are fully mixed during the heating process. After reaching and maintaining the predetermined temperature for a period of time, 1-10 grams of a polar polymer are added to the reactor, and high-temperature stirring continues until the polar polymer is completely dissolved and uniformly mixed with the elastomeric polymer to form a homogeneous molten mixture.

[0063] In some possible implementations, the mass ratio of the elastomeric polymer to the polar polymer is (100–200):(2–10). In this case, the polar polymer microdomains can effectively improve the adhesion and moisture barrier properties of the flexible encapsulation film surface, forming a viscoplastic surface that provides sufficient adhesion strength to the substrate to be encapsulated. Simultaneously, it helps maintain the mechanical properties of the flexible encapsulation film, avoiding a reduction in mechanical properties due to an excessively high proportion of polar polymer microdomains.

[0064] For example, the mass ratio of the elastomeric polymer to the polar polymer can be any point value or a range between any two point values, such as 100:2, 120:3, 150:5, 180:8, 100:5, 100:8, 100:10, 200:10, etc.

[0065] In some possible implementations, the elastomeric polymer includes at least one of styrene-butadiene-styrene, styrene-isoprene-styrene, styrene-ethylene-butene-styrene, styrene-isobutylene-styrene, styrene-propylene-styrene, and styrene-ethylene-propylene-styrene. These elastomeric polymers all possess excellent biocompatibility, gas barrier properties, thermo-oxidative stability, and are characterized by softness and tunable structural properties. In some specific embodiments, the elastomeric polymer includes styrene-isobutylene-styrene block copolymers (SIBS) with good thermal stability and low water vapor permeability.

[0066] In some possible implementations, the polar polymer includes at least one of maleic anhydride-grafted polypropylene, maleic anhydride-grafted polyethylene, maleic anhydride-grafted polyolefin elastomer, maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer, and glycidyl ether-grafted polypropylene. These polar polymers all exhibit high compatibility with the elastomer polymer, which is beneficial for forming hard-phase microdomains with good interfaces during phase separation from the elastomer polymer matrix. Furthermore, they possess strongly polar reactive groups, readily enhancing interfacial interactions by forming chemical bonds with other materials. In some specific embodiments, the polar polymer microdomains include PP-g-MAH.

[0067] In step S20 above: First, a suitable substrate is selected, and then the above precursor mixture solution is poured evenly onto the substrate. During this process, the various conditions for film formation must be strictly controlled so that the elastomeric polymer and the polar polymer can achieve micro-phase separation, forming a flexible encapsulation film with an elastomeric polymer surface and a viscoplastic surface.

[0068] In some possible implementations, the substrate undergoes plasma pretreatment to improve its surface hydrophilicity.

[0069] In some possible implementations, plasma pretreatment uses an argon-oxygen mixed gas, with an excitation frequency of 10MHz to 15MHz and a treatment time of 5min to 15min. Under these conditions, the hydrophilicity of the substrate can be sufficiently improved. For example, the excitation frequency of the plasma pretreatment substrate can be any typical but non-limiting value such as 10MHz, 11MHz, 12MHz, 13MHz, 14MHz, or 15MHz, or a range between any two values; the treatment time can be any typical but non-limiting value such as 5min, 8min, 10min, 12min, or 15min, or a range between any two values.

[0070] In some specific embodiments, a suitable substrate is selected, such as a glass plate or a glass petri dish. The surface of the substrate should be flat, clean, and free of oil and dust. It can then be pretreated with plasma to improve its surface hydrophilicity. The plasma pretreatment gas is an argon-oxygen mixture, the excitation frequency is 10MHz-15MHz, and the treatment time is 5min-15min.

[0071] In some possible implementations, the method of depositing the mixed slurry on the surface of the substrate includes solution casting, blade coating, or extrusion coating. In this case, mixed slurries prepared by solution casting are suitable for film preparation by solution casting or blade coating; mixed slurries prepared by high-temperature melting can be formed by extrusion coating to ensure uniform film thickness.

[0072] In some possible implementations, the microphase separation process includes: sealing and allowing the mixture to stand for 3 to 6 hours, followed by evaporation to remove the solvent from the mixed slurry at an evaporation rate of 0.4 μm / min to 0.7 μm / min. In this case, during the sealed standing process, the polar polymer forms microdomains, whose growth is limited by the influence of the elastomeric polymer, maintaining their micro-nano size; the formed microdomains are slowly deposited onto one side of the film layer under the influence of gravity. During solvent evaporation, the rising solvent vapor causes the microdomains to exhibit a gradient distribution within the film layer, forming a viscoplastic surface on one surface of the flexible encapsulation film. The distribution of polar polymer microdomains in the elastomeric polymer substrate depends on the phase separation between them and the host matrix, as well as the experimental conditions controlled under the corresponding film-forming conditions. During the film formation process, if the standing and sealing time of the mixed slurry is too short or the evaporation rate is too fast, the phase separation between the elastomer polymer and the polar polymer will be incomplete. If the standing and sealing time is too long or the evaporation rate is too short, the microdomains formed by the polar polymer will completely settle and separate at the bottom. Under these two experimental conditions, a viscoplastic surface layer cannot be obtained.

[0073] For example, the sealed standing time for microphase separation treatment can be any point value or an interval between any two points, such as 3h, 4h, 5h, 6h, etc., which are typical but not limiting. The evaporation rate can be any point value or an interval between any two points, such as 0.4, 0.5, 0.6, 0.7, which are typical but not limiting.

[0074] In some possible implementations, the drying conditions include drying under vacuum at a temperature of 80°C to 120°C for 12 to 24 hours. For example, the drying temperature can be any typical but non-limiting value, such as 80°C, 90°C, 100°C, 110°C, or 120°C, or a range between any two values; the drying time can be any typical but non-limiting value, such as 12 hours, 15 hours, 18 hours, 20 hours, or 24 hours, or a range between any two values. In this case, the solvent components in the film layer can be removed without affecting the performance of the flexible encapsulation film.

[0075] In some possible implementations, the steps of depositing a mixed slurry onto the surface of a substrate using solution casting, performing microscopic phase separation treatment, and drying to obtain a flexible encapsulation film with an elastomeric polymer surface and a viscoplastic surface include: First, pouring the mixed slurry into a glass petri dish pretreated with plasma. After sealing with aluminum foil and standing at room temperature for 3-6 hours, the solvent evaporation rate is controlled at 0.4 μm / min-0.7 μm / min by creating tiny pinholes in the aluminum foil. Subsequently, the organic solvent is allowed to evaporate slowly in a fume hood. During this process, it is necessary to finely control parameters such as the reactant concentration ratio, solvent type, and solvent evaporation rate to control the degree and rate of phase separation, ensuring that the film thickness is uniformly controlled between 0.25 mm and 1.2 mm. After drying, the film is slowly peeled off from the petri dish and placed in a vacuum oven for 12 hours to completely remove residual solvent, obtaining a flexible film.

[0076] In some possible implementations, the steps of depositing a mixed slurry onto the surface of a substrate using a blade coating method, performing micro-phase separation treatment, and drying to obtain a flexible encapsulation film with an elastomeric polymer surface and a viscoplastic surface include: First, after the mixed slurry is left to stand and sealed for 3 to 6 hours, it is uniformly coated onto a plasma-pretreated glass plate using a blade coater or scraper. During the coating process, the angle and pressure between the scraper and the substrate surface need to be precisely controlled to ensure the uniformity of the coating and the required thickness. The coating speed can be adjusted according to the viscosity of the solution and the required film thickness. After coating, the substrate is placed in a drying environment to allow the solvent to evaporate slowly at an evaporation rate of 0.4 μm / min to 0.7 μm / min. After the drying process is complete, the film is slowly peeled off from the substrate and finally stored in a vacuum oven for 12 hours to remove residual solvent, resulting in a flexible film.

[0077] In some possible implementations, the coated slurry is placed horizontally in an atmosphere filled with saturated solvent vapors such as toluene, allowed to stand, and then removed and allowed to evaporate naturally at room temperature. The coated slurry contains a certain proportion of volatile solvents. In a normal atmospheric environment, the solvent continuously evaporates, causing the solution concentration to gradually increase, and the evaporation rate changes as the solvent decreases. However, in a saturated vapor atmosphere, because the ambient vapor pressure and the vapor pressure at the solution surface are close to equilibrium, solvent evaporation is suppressed. Slowing down the evaporation rate allows the coated precursor solution more time to level, diffuse, and chemically react, thus forming a more uniform and dense film.

[0078] In some possible implementations, the steps of depositing a mixed slurry onto the surface of a substrate using an extrusion coating method, performing micro-phase separation treatment, and drying to obtain a flexible encapsulation film with an elastomeric polymer surface and a viscoplastic surface include: First, the mixed slurry prepared by high-temperature melting is heated and melted, then uniformly extruded and coated onto a polytetrafluoroethylene (PTFE) substrate, with precise control to ensure uniform coating thickness. Subsequently, the coated substrate is slowly cooled to 100°C and held at this temperature for 1-4 hours. Next, the melt is smoothly transferred to a 20°C environment for rapid cooling using a traction device. Finally, the naturally cooled film is peeled off from the substrate using the spraying action of an ethanol solution to obtain the flexible film.

[0079] In some possible implementations, films prepared by extrusion coating must have a thickness strictly controlled to no more than 120 micrometers to ensure the formation of the desired viscoplastic surface layer. Films that are too thick will fail to achieve the expected surface viscoplastic properties. As the film thickness gradually increases, the degrees of freedom of the surface molecular chains in the direction perpendicular to the film plane correspondingly increase. With thicker films, the surface constraint of the molecular chains in regions far from the substrate surface is significantly reduced, leading to increased entanglement of these chain segments. This increased entanglement may lengthen the diffusion path of surface layer molecular chains near the substrate. Conversely, when the film thickness decreases, the diffusion rate of molecular chains near the bottom surface may increase, thereby promoting compatibility between the polar microregions and the elastomeric polymer substrate, and imparting viscoplastic surface properties to the material by adjusting the conformation of the bottom surface molecular chains.

[0080] In some possible implementations, when preparing films from high-temperature molten mixtures via extrusion coating, the methods for controlling the phase separation of polar polymer microdomains from the host elastomer polymer include: altering the extrusion speed and pressure can affect the polymer flow state and phase separation process; higher extrusion speeds and pressures may subject the polymer molecular chains to greater shear forces, promoting phase separation. However, excessively high speeds and pressures can also lead to defects in the film, such as uneven thickness and surface roughness. Furthermore, the cooling rate after extrusion also significantly impacts phase separation; faster cooling rates allow the polymer to solidify rapidly, restricting molecular chain movement and reducing the degree of phase separation, while slower cooling rates allow the molecular chains more time to adjust and separate.

[0081] Thirdly, embodiments of this application provide a flexible electronic device, which includes the aforementioned flexible encapsulation film and / or the flexible encapsulation film prepared by the aforementioned method.

[0082] The flexible electronic device in this application includes the aforementioned flexible encapsulation film. This flexible encapsulation film can not only adhere tightly to the substrate of various modules of the flexible electronic device, but also possesses high stretchability and high barrier properties, effectively bridging the contradiction between adhesion, barrier properties, and stretchability in the field of flexible electronic packaging. Good adhesion ensures that the encapsulation film adheres tightly to the device surface, making it less prone to detachment or damage under external forces, maintaining the integrity of the encapsulation structure, and effectively preventing moisture, oxygen, and other contaminants from entering the device, thereby protecting the device from damage and improving the reliability of the encapsulation. The excellent stretchability of the encapsulation film can adapt to various deformations of the flexible electronic device during use without causing damage to the encapsulation structure or performance degradation. It better withstands mechanical stress, reducing problems such as film cracking and detachment caused by deformation, thereby improving the durability of the flexible electronic device. Hermeticity effectively prevents small molecules such as water vapor and oxygen from entering the device, avoiding corrosion or oxidation of the circuit, thereby extending the device's lifespan, reducing performance fluctuations caused by environmental factors (such as humidity and temperature changes), and improving the reliability and stability of the flexible electronic device.

[0083] To enable those skilled in the art to clearly understand the above-described implementation details and operations of this application, and to highlight the significant advancements in the performance of the flexible encapsulation film and its preparation method, as well as the flexible electronic devices described in the embodiments of this application, the following examples illustrate the above technical solutions.

[0084] Example 1

[0085] A flexible encapsulation film, prepared by solution casting, is a stretchable, high-barrier encapsulation film with surface adhesive properties, comprising the following steps: First, 1 g of PP-g-MAH (maleic anhydride-grafted polypropylene) particles are dissolved in 200 ml of toluene solution and stirred at 130 °C for 2 hours, while reflux is performed using circulating water. After the PP-g-MAH is completely dissolved, 50 g of SIBS (styrene-isobutylene-styrene block copolymer) masterbatch is added to the solution, and stirring is continued at 85 °C for 3 hours. Next, a certain mass of the above PP-g-MAH / SIBS precursor mixed solution is poured into a glass petri dish pretreated with oxygen plasma. Then, the petri dish is sealed with aluminum foil at room temperature and allowed to stand for 4 hours. The solvent evaporation rate is precisely controlled to be 0.4 μm / min to 0.7 μm / min by creating tiny pinholes on the aluminum foil. The petri dish is then placed horizontally in a fume hood to allow the toluene solvent to evaporate slowly. After the solvent has evaporated, the flexible encapsulation film is gently peeled off from the petri dish and stored in a vacuum oven at 100°C for 12 hours to remove residual solvent, thus obtaining a flexible encapsulation film in which the average particle size of the polar polymer microdomains is 550 nm and the mass percentage is 2%.

[0086] Example 2

[0087] A flexible encapsulation film, prepared by a blade coating method, is a stretchable, high-barrier encapsulation film with surface adhesiveness. The method includes the following steps: First, 5 grams of PP-g-MAH particles are dissolved in 400 ml of toluene solution. This process is carried out at 130°C with continuous stirring for 2 hours, during which reflux is achieved through a circulating water system to obtain solution A. 200 grams of SIBS raw material are dissolved in 1000 ml of n-hexane solution, with continuous stirring until completely dissolved to obtain solution B. Solution A and solution B are mixed to form a homogeneous, viscous mixture. In a cleanroom environment, the mixture is poured onto a plasma-pretreated glass substrate and uniformly coated using a blade. During the coating process, the coating speed and pressure are precisely controlled to ensure the uniformity of the coating and achieve the desired thickness. Subsequently, the coated substrate is placed horizontally in an atmosphere filled with saturated toluene vapor and left to stand for 2 hours. Then, it is removed and the solvent is allowed to evaporate naturally at room temperature. After the drying process is completed, the film is slowly peeled off from the substrate and placed in a vacuum oven for 12 hours to completely remove the residual solvent, thus obtaining a flexible encapsulation film in which the average particle size of the polar polymer microdomains is 90 nm and the mass percentage is 2.5%.

[0088] Example 3

[0089] A flexible encapsulation film, prepared by extrusion coating, is a stretchable, high-barrier encapsulation film with surface adhesive properties. The method includes the following steps: First, 200g of SIBS masterbatch, 30g of polyisobutylene liquid (PB 1300), and 8g of naphthenic oil are added to a reactor in a single batch. The temperature is then gradually increased to 170°C. During this period, a stirring device is activated to ensure thorough mixing of the materials during the heating process. After reaching the predetermined temperature, it is maintained for 45 minutes. Then, 4g of PP-g-MAH is added to the reactor, and high-temperature stirring continues until a homogeneous molten mixture is formed. Next, the prepared adhesive is heated and melted, and then uniformly coated onto a PTFE substrate using an extrusion coating machine. During the coating process, coating parameters must be precisely controlled to ensure consistent coating thickness. After coating, the substrate is slowly cooled to 100°C and held at this temperature for 1 hour to ensure uniform curing of the adhesive. Afterward, the substrate is smoothly transferred to a 20°C environment using a traction device for rapid cooling. Finally, with the aid of an ethanol solution, the naturally cooled film was peeled off from the substrate to obtain a flexible encapsulation film, wherein the average particle size of the polar polymer microdomains is 80 nm and the mass percentage is 1.7%.

[0090] Example 4

[0091] A flexible encapsulation film, the main difference from Example 1 is that the polar polymer is a styrene-ethylene / butene-styrene block copolymer (SEBS).

[0092] The procedure includes the following steps: First, 1 g of PP-g-MAH is dissolved in 200 ml of toluene solution and stirred at 130 °C for 2 hours, while reflux is performed using circulating water. After the PP-g-MAH is completely dissolved, 75 g of SEBS masterbatch is added to the solution, and stirring continues at 80 °C for 1 hour. Next, a certain mass of the PP-g-MAH / SEBS precursor mixture is poured into a glass culture dish pretreated with oxygen plasma. Then, the culture dish is sealed with aluminum foil at room temperature and allowed to stand for 3 hours. The solvent evaporation rate is precisely controlled at 0.4 μm / min to 0.7 μm / min by creating tiny pinholes in the aluminum foil. Afterward, the culture dish is placed horizontally in a fume hood to allow the toluene solvent to evaporate slowly. After the solvent has evaporated, the flexible encapsulation film is gently peeled off from the petri dish and stored in a vacuum oven at 100°C for 12 hours to remove residual solvent, thus obtaining a flexible encapsulation film in which the average particle size of the polar polymer microdomains is 380 nm and the mass percentage is 1.3%.

[0093] Example 5

[0094] A flexible encapsulation film, the main difference from Example 1 is that the polar polymer is a styrene-ethylene / propylene-styrene block copolymer (SEPS).

[0095] The procedure includes the following steps: First, 1 g of PP-g-MAH is dissolved in 200 ml of toluene solution and stirred at 130 °C for 2 hours, while reflux is performed using circulating water. After the PP-g-MAH is completely dissolved, 50 g of SEPS masterbatch is added to the solution, and stirring continues at 80 °C for 1 hour. Next, a certain mass of the PP-g-MAH / SEPS precursor mixture is poured into a glass culture dish pretreated with oxygen plasma. Then, the culture dish is sealed with aluminum foil at room temperature and allowed to stand for 3 hours. The solvent evaporation rate is precisely controlled at 0.4 μm / min to 0.7 μm / min by creating tiny pinholes in the aluminum foil. Afterward, the culture dish is placed horizontally in a fume hood to allow the toluene solvent to evaporate slowly. After the solvent has evaporated, the flexible encapsulation film is gently peeled off from the petri dish and stored in a vacuum oven at 100°C for 12 hours to remove residual solvent, thus obtaining a flexible encapsulation film in which the average particle size of the polar polymer microdomains is 350 nm and the mass percentage is 2%.

[0096] Example 6

[0097] A flexible encapsulation film, the main difference from Example 1 is that the polar polymer is a styrene-butadiene-styrene block copolymer (SBS).

[0098] The procedure includes the following steps: First, 1 g of PP-g-MAH particles are dissolved in 200 ml of toluene solution and stirred at 130 °C for 2 hours, while reflux is performed using circulating water. After the PP-g-MAH is completely dissolved, 50 g of SBS masterbatch is added to the solution, and stirring continues at 80 °C for 1 hour. Next, a certain mass of the PP-g-MAH / SBS precursor mixture is poured into a glass culture dish pretreated with oxygen plasma. Then, the culture dish is sealed with aluminum foil at room temperature and allowed to stand for 3 hours. The solvent evaporation rate is precisely controlled to be 0.4 μm / min to 0.7 μm / min by creating tiny pinholes in the aluminum foil. The culture dish is then placed horizontally in a fume hood to allow the toluene solvent to evaporate slowly. After the solvent has evaporated completely, the flexible encapsulation film is gently peeled off from the culture dish and stored in a vacuum oven at 100 °C for 12 hours to remove residual solvent. A flexible encapsulation film was prepared, wherein the average particle size of the polar polymer microdomains was 260 nm and the mass percentage was 2%.

[0099] Example 7

[0100] A flexible encapsulation film, the main difference from Example 1 is that the polar polymer is a styrene-isoprene-styrene block copolymer (SIS).

[0101] The procedure includes the following steps: First, 1 g of PP-g-MAH particles are dissolved in 200 ml of toluene solution and stirred at 120 °C for 2 hours, while reflux is performed using circulating water. After the PP-g-MAH is completely dissolved, 50 g of SIS masterbatch is added to the solution, and stirring continues at 80 °C for 1 hour. Next, a certain mass of the PP-g-MAH / SIS precursor mixture is poured into a glass culture dish pretreated with oxygen plasma. Then, the culture dish is sealed with aluminum foil at room temperature and allowed to stand for 3 hours. The solvent evaporation rate is precisely controlled at 0.4 μm / min to 0.7 μm / min by creating tiny pinholes in the aluminum foil. The culture dish is then placed horizontally in a fume hood to allow the toluene solvent to evaporate slowly. After the solvent has evaporated completely, the flexible encapsulation film is gently peeled off from the culture dish and stored in a vacuum oven at 100 °C for 12 hours to remove residual solvent. A flexible encapsulation film was prepared, wherein the average particle size of the polar polymer microdomains was 90 nm and the mass percentage was 2%.

[0102] Example 8

[0103] A flexible encapsulation film, the main difference from Example 1 is that the elastomeric polymer is maleic anhydride-grafted polyethylene (PE-g-MAH).

[0104] The procedure includes the following steps: First, 2g of PE-g-MAH particles are dissolved in 200ml of toluene solution and stirred at 130℃ for 2 hours, while reflux is performed using circulating water. After the PE-g-MAH is completely dissolved, 50g of SIBS masterbatch is added to the solution, and stirring continues at room temperature for 1 hour. Next, a certain mass of the PE-g-MAH / SIBS precursor mixture is poured into a glass culture dish pretreated with oxygen plasma. Then, the culture dish is sealed with aluminum foil at room temperature and allowed to stand for 3 hours. The solvent evaporation rate is precisely controlled at 0.4μm / min to 0.7μm / min by creating tiny pinholes in the aluminum foil. The culture dish is then placed horizontally in a fume hood to allow the toluene solvent to evaporate slowly. After the solvent has evaporated completely, the flexible encapsulation film is gently peeled off from the culture dish and stored in a vacuum oven at 100℃ for 12 hours to remove residual solvent. A flexible encapsulation film was prepared, wherein the average particle size of the polar polymer microdomains was 800 nm and the mass percentage was 4%.

[0105] Example 9

[0106] A flexible encapsulation film, the main difference from Example 1 is that the elastomer polymer is a maleic anhydride-grafted polyolefin elastomer (POE-g-MAH).

[0107] The procedure includes the following steps: First, 2g of POE-g-MAH particles are dissolved in 200ml of toluene solution and stirred at 130℃ for 2 hours, while reflux is performed using circulating water. After the POE-g-MAH is completely dissolved, 50g of SIBS masterbatch is added to the solution, and stirring continues at room temperature for 1 hour. Next, a certain mass of the POE-g-MAH / SIBS precursor mixture is poured into a glass culture dish pretreated with oxygen plasma. Then, the culture dish is sealed with aluminum foil at room temperature and allowed to stand for 3 hours. The solvent evaporation rate is precisely controlled at 0.4μm / min to 0.7μm / min by creating tiny pinholes in the aluminum foil. The culture dish is then placed horizontally in a fume hood to allow the toluene solvent to evaporate slowly. After the solvent has evaporated completely, the flexible encapsulation film is gently peeled off from the culture dish and stored in a vacuum oven at 100℃ for 12 hours to remove residual solvent. A flexible encapsulation film was prepared, wherein the average particle size of the polar polymer microdomains was 680 nm and the mass percentage was 4%.

[0108] Example 10

[0109] A flexible encapsulation film, the main difference from Example 1 is that the elastomer polymer is a glycidyl ether grafted polyolefin elastomer (POE-g-GMA).

[0110] The procedure includes the following steps: First, 2g of POE-g-GMA particles are dissolved in 200ml of toluene solution and stirred at 120℃ for 2 hours, while reflux is performed using circulating water. After the POE-g-GMA is completely dissolved, 40g of SIBS masterbatch is added to the solution, and stirring continues at room temperature for 1 hour. Next, a certain mass of the above POE-g-GMA / SIBS precursor mixed solution is poured into a glass culture dish pretreated with oxygen plasma. Then, the culture dish is sealed with aluminum foil at room temperature and allowed to stand for 3 hours. The solvent evaporation rate is precisely controlled at 0.4μm / min to 0.7μm / min by creating tiny pinholes in the aluminum foil. The culture dish is then placed horizontally in a fume hood to allow the toluene solvent to evaporate slowly. After the solvent has evaporated completely, the flexible encapsulation film is gently peeled off from the culture dish and stored in a vacuum oven at 100℃ for 12 hours to remove residual solvent. A flexible encapsulation film was prepared, wherein the average particle size of the polar polymer microdomains was 80 nm and the mass percentage was 5%.

[0111] Example 11

[0112] A flexible encapsulation film, the main difference from Example 1 is that the concentration ratio of PP-g-MAH is increased so that the mass percentage of polar polymer microdomains in the obtained flexible encapsulation film is 5%.

[0113] Example 12

[0114] A flexible encapsulation film, which differs from Example 1 in that the concentration ratio of PP-g-MAH is increased so that the mass percentage of polar polymer microdomains in the obtained flexible encapsulation film is 7.5%.

[0115] Example 13

[0116] A flexible encapsulation film, the main difference from Example 1 is that the concentration ratio of PP-g-MAH is reduced so that the mass percentage of polar polymer microdomains in the obtained flexible encapsulation film is 1%.

[0117] Example 14

[0118] A flexible encapsulation film, which differs from Example 1 in that the concentration ratio of PP-g-MAH is increased, so that the mass percentage of polar polymer microdomains in the obtained flexible encapsulation film is 11%.

[0119] Comparative Example 1

[0120] A flexible encapsulation film, prepared by a blade coating method, comprises the following steps: First, 200 g of SIBS raw material is dissolved in 1000 ml of n-hexane solution, and stirred continuously until completely dissolved to obtain solution B. In a dust-free environment, the mixture is poured onto a plasma-pretreated glass substrate and uniformly coated using a blade. During the coating process, the coating speed and pressure are precisely controlled to ensure the uniformity of the coating and achieve the desired thickness. Subsequently, the coated substrate is placed horizontally in an atmosphere filled with saturated toluene vapor and left to stand for 2 hours. Then, it is removed and the solvent is allowed to evaporate naturally at room temperature. After the drying process, the film is slowly peeled off from the substrate and placed in a vacuum oven for 12 hours to completely remove residual solvent, thus obtaining the flexible encapsulation film.

[0121] Comparative Example 2

[0122] A flexible encapsulation film, prepared by a blade coating method, comprises the following steps: First, 5 g of PP-g-MAH particles are dissolved in 400 ml of toluene solution at 130°C with continuous stirring for 2 hours, during which reflux is achieved via a circulating water system to obtain solution A. 200 g of SIBS raw material is dissolved in 1000 ml of n-hexane solution with continuous stirring until completely dissolved to obtain solution B. Solution A and solution B are mixed to form a homogeneous, viscous mixture. In a cleanroom environment, the mixture is poured onto a plasma-pretreated glass substrate and uniformly coated using a blade. During the coating process, the coating speed and pressure are precisely controlled to ensure coating uniformity and achieve the desired thickness. Subsequently, the coated substrate is horizontally removed and the solvent is allowed to evaporate naturally at room temperature. After the drying process, the film is slowly peeled off from the substrate and placed in a vacuum oven for 12 hours to thoroughly remove residual solvent.

[0123] Comparative Example 3

[0124] A flexible encapsulation film, prepared by polar polymer deposition to form a polar polymer layer via a blade coating method, includes the following steps: First, 5 g of PP-g-MAH particles are dissolved in 400 ml of toluene solution. This process is carried out at 130°C with continuous stirring for 2 hours, during which reflux is achieved through a circulating water system to obtain solution A. 200 g of SIBS raw material is dissolved in 1000 ml of n-hexane solution, with continuous stirring until completely dissolved to obtain solution B. Solution A and solution B are mixed to form a homogeneous and viscous mixture. In a dust-free environment, the mixture is poured onto a plasma-pretreated glass substrate and uniformly coated using a blade. During the coating process, the coating speed and pressure are precisely controlled to ensure the uniformity of the coating and achieve the desired thickness. Subsequently, the coated substrate is placed horizontally in an atmosphere filled with saturated toluene vapor and left to stand for 12 hours. Then, it is removed and the solvent is allowed to evaporate naturally at room temperature. After the drying process, the film is slowly peeled off from the substrate and placed in a vacuum oven for 12 hours to completely remove residual solvent.

[0125] To verify the progressiveness of the embodiments of this application, the following performance tests were performed on the above embodiments and comparative examples:

[0126] 1. Characterize the structure of the sample prepared in Example 1:

[0127] The surface microstructure of the flexible encapsulation film before and after the addition of PP-g-MAH was observed using atomic force microscopy (AFM), as shown in Figure 3. The results show that the size distribution of polystyrene (PS) nanodomains adjacent to the PP-g-MAH microdomains changed significantly, which confirms that the introduction of PP-g-MAH microdomains promoted the rearrangement of the molecular chains of the SIBS surface layer composed of the PS hard phase and the PIB soft phase.

[0128] Furthermore, the grazing incidence wide-angle X-ray scattering (GIWAXS) spectrum in Figure 4 reveals the disappearance of the two characteristic scattering peaks originally belonging to PS, confirming at the molecular scale that the introduction of PP-g-MAH microdomains makes the PS nanodomain structure more disordered. Since PS nanodomains act as physical crosslinking agents in the SIBS network, the reduction in their size and order significantly increases the mobility of surface polymer chains, thereby causing the flexible encapsulation film surface to exhibit adhesive properties.

[0129] In addition, the hard phase PP-g-MAH embedded in the viscoplastic surface plays a toughening role. When we gently press the two surface layers and slowly peel them off, we can observe obvious surface stringing. However, the surface of the elastomer polymer without distributed polar polymer microdomains does not exhibit stringing (Figure 5). This phenomenon highlights the viscoplastic deformation behavior of the surface layer.

[0130] 2. Characterization of the interfacial adhesion properties of the samples prepared in Example 1:

[0131] Figure 6 comprehensively demonstrates the superior performance of the surface-adhesive flexible encapsulation film in adhesion to plastics, elastomers, and hydrogels, including its flexibility, stretchability, and stability. Specifically, Figure 6a shows the interface between the film and a polyethylene terephthalate (PET) substrate, which maintains a tight adhesion even after 7 days of bending and water immersion. Figure 6b shows the interface between the film and Ecoflex silicone rubber, which maintains a stretchability of 280% after immersion in acidic or alkaline solutions for more than 15 days. Figure 6c shows the tight adhesion between the film and a polyvinyl alcohol (PVA) hydrogel, which maintains a tight bond even after the hydrogel dries and wrinkles due to volume shrinkage. These results demonstrate that the prepared surface-adhesive flexible encapsulation film can form conformal, tough, and stretchable adhesions with various device modules and substrates.

[0132] 3. Characterization of the mechanical properties and water vapor barrier properties of the samples prepared in Example 1:

[0133] Figure 7a shows a comparison of water vapor transmission rate and mechanical modulus of different flexible encapsulation films. Plastics are malleable polymer materials, including PC (polycarbonate), PI (polyimide), PVC (polyvinyl chloride), PET (polyethylene terephthalate), PS (polystyrene-based plastics), LDPF (low-density polyethylene), PEN (polyethylene naphthalate), PVDC (polyvinylidene chloride), PVDF (polyvinylidene fluoride), HDPE (high-density polyethylene), and PAYLEN C (poly(p-dichlorotoluene)). Elastomers are elastomers, including PDMS (polydimethylsiloxane), IIR (butyl rubber), POE (polyolefin elastomer), SEBS (styrene-ethylene-butene-styrene block copolymer), and PIB (polyisobutylene). The flexible encapsulation film with surface adhesiveness has a water vapor transmission rate of only 0.09 g / m² under the same test conditions. 2The per-day value is comparable to that of some high-barrier plastics such as Parylenc C, demonstrating excellent barrier performance. Figure 7b shows a comparison of the mechanical curves with and without PP-g-MAH microdomains, indicating that the formation of the viscoplastic surface layer did not affect the overall mechanical properties of the flexible encapsulation film. Figure 7c compares the barrier performance changes of a 0.25 mm thick flexible encapsulation film with viscoplastic surface characteristics after different stretching cycles. The results show that even after millions of stretching cycles, its water vapor transmission rate remains stable, proving that the film can maintain its reliable barrier performance under large deformation conditions.

[0134] 4. Tests were conducted on the surface indentation residue of the viscoplastic surface of the flexible encapsulation film prepared by the large-area coating method in Example 2 and the elastomeric polymer surface of the encapsulation film of pure elastomeric polymer prepared by the large-area coating method in Comparative Example 1. As shown in Figure 8, i→ii→iii represent the indentation needle before pressure application, during pressure application, and after pressure application, respectively. The experimental results clearly reveal the elastic properties of the pure elastomeric polymer surface. In contrast, the elastomeric surface exhibited adhesion to the indentation needle and significant fragmentation after pressure application. This observation provides direct and compelling evidence for the existence of surface viscoplasticity.

[0135] 5. The moisture barrier performance, stretchability, and adhesion to the viscoplastic surface of the flexible encapsulation films prepared in the above embodiments and comparative examples were tested respectively:

[0136] ① Water vapor barrier performance test (water vapor transmission rate): The test was conducted using a Mocon (USA) AQUATRAN 3 water vapor transmission rate instrument, with a test range of 0.00005~5g / m 2 / day (test area 50cm) 2 Temperature range: 10~40℃, humidity range: 5~90%RH, 100%RH. The specific operating procedure is as follows: First, the film to be tested is clamped in the test chamber. Dry nitrogen is used to purge moisture from the chamber. Then, pure, dry carrier gas is introduced into the infrared sensor to generate a stable zero value. Next, the temperature is controlled at 38℃ and the humidity at 90%RH. Water vapor is introduced to the outside of the test chamber. Water molecules permeate through the sample to the inside of the chamber, and the flowing dry carrier gas conducts the permeated water molecules to the infrared sensor. Finally, the infrared sensor senses the proportion of water molecules, generating a current that is input to the load resistor. The computer software calculates the precise water vapor transmission rate based on the changes in current and resistance.

[0137] ② Tensile property test (Young's modulus): The stress-strain curve was measured using a CMT6203 universal testing machine equipped with a 100N load cell. The film samples were cut into dumbbell shapes with a width of 5mm and a length of 80mm using a customized small punching machine. During the test, the tensile speed was maintained at 100mm / min, and each group of samples was tested at least five times in parallel. The average value of the results was taken.

[0138] ③ Adhesion test of viscoplastic surface (interfacial peel strength): Under room temperature conditions, the viscoplastic surface of the film sample was bonded to a PET plastic substrate. The specific process is as follows: First, ensure that the surfaces of the film and the plastic substrate to be laminated are clean and free of dust, oil, or other impurities. Then, according to the predetermined lamination sequence, place the film and the plastic substrate in the working area of ​​the vacuum laminator and laminate at 125℃ and 70kPa for 3 minutes. After lamination, allow the sample to cool naturally to room temperature, remove it, and cut it. Install a 180° peel fixture on a universal testing machine, adjust the sample position to ensure that the bonding surface of the film forms a 180° angle with the tensile surface, and fix the other end of the sample to the upper fixture. Set the peel speed to 30mm / min and start the test. After the test, record and analyze the peel force versus peel distance curve during the peeling process to evaluate the bonding strength.

[0139] The test results are shown in Table 1 below:

[0140] Table 1

[0141] The test results above show that the flexible encapsulation film prepared in this application exhibits excellent comprehensive performance: it not only has extremely low water vapor transmission rate, ensuring excellent barrier performance, but also possesses good elasticity and interfacial adhesion. These characteristics together endow the film with reliability and practicality in flexible encapsulation applications. In particular, Examples 4, 5, and 7 have relatively high water vapor transmission rates due to the relatively high water permeability of the polar polymers used compared to the polar polymers used in other examples and comparative examples. In Comparative Example 1, the encapsulation film made of a pure elastomeric polymer, and in Comparative Example 2, the polar polymer microdomains are uniformly distributed throughout the encapsulation film. The interfacial peel strength between the film and the encapsulation substrate is significantly reduced, and the surface adhesion is significantly reduced. In Comparative Example 3, the polar polymer layer is deposited, resulting in delamination of the film, which leads to a significant decrease in film stability, a significant increase in Young's modulus, and a significant decrease in film flexibility.

[0142] The above are merely optional embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A flexible encapsulation film, characterized in that, The flexible encapsulation film uses an elastomeric polymer with flexible and rigid segments as a substrate. The flexible encapsulation film includes an elastomeric polymer surface and a viscoplastic surface, in which hard-phase polar polymer microdomains are discretely distributed.

2. The flexible encapsulation film as described in claim 1, characterized in that, In the flexible encapsulation film, the doping concentration of the polar polymer microdomains increases along the direction from the elastomeric polymer surface to the viscoplastic surface.

3. The flexible encapsulation film as described in claim 1, characterized in that, In the flexible encapsulation film, the mass percentage of the polar polymer microdomains is 2% to 10%.

4. The flexible encapsulation film as described in claim 1, characterized in that, The average particle size of a single polar polymer microdomain is 50 nm to 2 μm.

5. The flexible encapsulation film as described in claim 1, characterized in that, The thickness of the flexible encapsulation film is 10μm to 2mm.

6. The flexible encapsulation film according to any one of claims 1 to 5, characterized in that, The elastomeric polymer includes styrene elastomeric polymers.

7. The flexible encapsulation film as described in claim 6, characterized in that, The elastomer polymer includes at least one of styrene-butadiene-styrene, styrene-isoprene-styrene, styrene-ethylene-butene-styrene, styrene-isobutene-styrene, styrene-propylene-styrene, and styrene-ethylene-propylene-styrene.

8. The flexible encapsulation film according to any one of claims 1 to 5, characterized in that, The polar polymer microdomains include at least one of maleic anhydride-grafted polymers and glycidyl ether-grafted polymers.

9. The flexible encapsulation film as described in claim 8, characterized in that, The polar polymer microdomains include at least one of maleic anhydride-grafted polypropylene, maleic anhydride-grafted polyethylene, maleic anhydride-grafted polyolefin elastomer, maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer, and glycidyl ether-grafted polypropylene.

10. A method for preparing a flexible encapsulation film, characterized in that, Includes the following steps: Elastomer polymers and polar polymers are mixed into a slurry; The mixed slurry is deposited on the surface of a substrate and subjected to micro-phase separation treatment, so that the polar polymer forms a hard phase microdomain structure distributed on one side of the film layer surface. After drying, a flexible encapsulation film with an elastomeric polymer surface and a viscoplastic surface is obtained; the polar polymer microdomains are discretely distributed in the viscoplastic surface.

11. The method for preparing the flexible encapsulation film as described in claim 10, characterized in that, The preparation method of the mixed slurry includes: dissolution method or melting method; And / or, the method of depositing the mixed slurry on the surface of the substrate includes solution casting, blade coating or extrusion coating; And / or, the microphase separation process includes: sealing and standing for 3 to 6 hours, then evaporating and removing the solvent from the mixed slurry at an evaporation rate of 0.4 μm / min to 0.7 μm / min; And / or, the substrate is pretreated with plasma; And / or, the drying conditions include drying under vacuum conditions at a temperature of 80°C to 120°C for 12 to 24 hours.

12. The method for preparing the flexible encapsulation film as described in claim 11, characterized in that, The steps of the dissolution method include: preparing solutions of the elastomer polymer and the polar polymer separately, and then performing a blending treatment to obtain the mixed slurry; And / or, the steps of the melt method include: mixing and melting the elastomer polymer with a plasticizer and a viscosity reducer, then adding the polar polymer and mixing and melting again to obtain the mixed slurry; And / or, the plasma pretreatment uses an argon-oxygen mixed gas, with an excitation frequency of 10MHz to 15MHz and a treatment time of 5min to 15min.

13. The method for preparing the flexible encapsulation film as described in claim 12, characterized in that, The concentration of the elastomer polymer solution is 50 mg / mL to 500 mg / mL; And / or, the concentration of the polar polymer solution is 0.5 mg / mL to 25 mg / mL; And / or, the temperature conditions for the melting method are 140℃~200℃; And / or, the mass ratio of the elastomer polymer to the plasticizer and the viscosity reducer is (200-400):(20-100):(2-15); And / or, the plasticizer comprises polyisobutylene liquid rubber with an average molecular weight of 400 to 2000; And / or, the viscosity reducer includes at least one of naphthenic oil, paraffin oil, and aromatic oil.

14. The method for preparing the flexible encapsulation film according to any one of claims 10 to 13, characterized in that, The mass ratio of the elastomeric polymer to the polar polymer is (100-200):(2-10); And / or, the elastomer polymer includes at least one of styrene-butadiene-styrene, styrene-isoprene-styrene, styrene-ethylene-butene-styrene, styrene-isobutene-styrene, styrene-propylene-styrene, and styrene-ethylene-propylene-styrene; And / or, the polar polymer includes at least one of maleic anhydride-grafted polypropylene, maleic anhydride-grafted polyethylene, maleic anhydride-grafted polyolefin elastomer, maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer, and glycidyl ether-grafted polypropylene.

15. A flexible electronic device, characterized in that, The flexible electronic device includes a flexible encapsulation film as described in any one of claims 1 to 4 and / or a flexible encapsulation film prepared by the method described in any one of claims 5 to 8.

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