Difunctional polyethylene glycol terephthalate sheath-core nano-micron fiber structure

Abstract

The invention relates to the technical field of multifunctional nanofibers, and discloses a difunctional polyethylene glycol terephthalate skin-core nano-micron fiber structure which comprises an inner core layer and an outer skin layer, the inner core layer is formed by compounding polyethylene glycol terephthalate and a polyethylene glycol type phase change material, and the outer skin layer is formed by compounding a polyethylene glycol type phase change material and a polyethylene glycol type phase change material; the outer skin layer is modified polyethylene glycol terephthalate, a luminescence agent Eu (CA) 3 (Phen) is doped, the mass percentage of the polyethylene glycol phase change material and the polyethylene glycol terephthalate is 10-60 wt%, and the molecular weight of polyethylene glycol in the polyethylene glycol phase change material is 600-6000. A polyethylene glycol phase change material is dissolved in hexafluoroisopropanol through an electrostatic spinning coaxial spinning technology to prepare an inner core layer spinning solution, the inner core layer spinning solution does not need to be used after being independently packaged, the process is simplified, the size does not need to be controlled, the performance is stable, and the preparation method is suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of multifunctional nanofibers, in particular to a bifunctional polyethylene terephthalate skin-core nano-micron fiber structure. Background Art

[0002] Polyethylene terephthalate (PET) is a widely used linear aromatic polyester polymer with excellent mechanical properties, chemical stability, and processability. Its molecular chain structure imparts excellent fiber-forming properties, allowing it to be spun into nano- to micron-sized fibers. These fibers possess both high strength and toughness, making them widely used in a variety of fields, including textiles, packaging, and automotive. In the field of functional fibers, photoluminescent materials are a class of functional materials that fluoresce under specific excitation light. Among them, Eu(CA)3(Phen), a rare earth benzoate luminescent material containing an amide bond, exhibits stable and vibrant fluorescence due to the characteristic luminescence properties of the rare earth ion Eu³⁺, and has important applications in warning and anti-counterfeiting scenarios. Polyethylene glycol (PEG)-based phase change materials are a class of polymer compounds with solid-liquid phase transition properties. They can store and release heat at temperatures near human body temperature, making them ideal temperature-control functional materials. Combining luminescent materials with PET can take advantage of PET's fiber-forming properties and structural stability to solve the problems of easy aggregation and poor mechanical properties of luminescent materials when used alone, while giving the fiber photoluminescence function.

[0003] At present, the phase change energy storage materials used for human body temperature regulation are mainly paraffin, octadecane and polyethylene glycol. Although the phase transition temperature of these materials is close to that of the human body, they are mostly solid-liquid phase change materials and will change from solid to flowable liquid during phase change. Therefore, they need to be encapsulated when used. However, since the diameter of conventional fiber products is between 10-20μm and the diameter of some fiber products is only a few microns, the size of the encapsulated phase change material must be below 500nm, which increases the difficulty of encapsulation technology and limits its wide application. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a bifunctional polyethylene terephthalate skin-core nano-micron fiber structure, which solves the problem that the size of the encapsulated phase change material must be below 500nm, which increases the difficulty of packaging technology and limits its wide application.

[0005] To achieve the above objectives, the present invention is implemented through the following technical scheme: a bifunctional polyethylene terephthalate skin-core nano-micron fiber structure, including an inner core layer and an outer skin layer, the inner core layer is composited by polyethylene terephthalate and a polyethylene glycol phase change material, the mass percentage of the polyethylene glycol phase change material and the polyethylene terephthalate is 10wt%~60wt%, the molecular weight of the polyethylene glycol in the polyethylene glycol phase change material is 600~6000, the outer skin layer is modified polyethylene terephthalate, doped with the luminescent agent Eu(CA)3(Phen), the mass percentage of the polyethylene terephthalate and the luminescent agent Eu(CA)3(Phen) is 6wt%~12wt%, and the outer skin layer covers the inner core layer to form a composite integral structure.

[0006] Preferably, the diameter of the inner core layer is in the range of 150 nm to 250 nm, and the thickness of the outer skin layer is in the range of 50 nm to 500 nm.

[0007] Preferably, the outer skin layer covers the inner core layer by electrospinning coaxially to form an integrated organically combined and encapsulated structure.

[0008] Preferably, a method for preparing a bifunctional polyethylene terephthalate skin-core nano-micron fiber structure comprises the following steps:

[0009] preparing a sheath layer spinning solution, wherein the sheath layer spinning solution is composed of polyethylene terephthalate and a luminescent agent Eu(CA)3(Phen);

[0010] preparing an inner core layer spinning solution, wherein the inner core layer spinning solution is composed of polyethylene terephthalate and a polyethylene glycol phase change material;

[0011] The outer skin layer spinning solution and the inner core layer spinning solution are prepared into nanofibers by using electrospinning coaxial spinning technology;

[0012] The obtained nanofibers are dried to obtain bifunctional polyethylene terephthalate sheath-core nano-micron fibers;

[0013] Preferably, the specific steps of preparing the outer skin layer spinning solution are as follows:

[0014] The luminescent agent Eu(CA)3(Phen) and polyethylene terephthalate are placed in a vacuum drying oven and heated to 60°C to 80°C to remove moisture. 1g to 3g of dry polyethylene terephthalate is weighed and added to 5.0ml to 6.0ml of hexafluoroisopropanol. The mixture is stirred continuously at room temperature using a magnetic stirring device for 6 to 8 hours to form a polyethylene terephthalate spinning solution with a concentration of 10wt% to 30wt%.

[0015] 6 wt % to 12 wt % of Eu(CA)3(Phen) based on the mass of polyethylene terephthalate was added to the polyethylene terephthalate spinning solution, and the mixture was stirred for 8 hours and then allowed to stand for 2 hours to obtain a sheath layer spinning solution.

[0016] Preferably, the specific steps of preparing the inner core layer spinning solution are as follows:

[0017] 1 g to 3 g of dry polyethylene terephthalate is added to 5.0 ml to 6.0 ml of hexafluoroisopropanol, and stirred continuously for 6 to 8 hours at room temperature using a magnetic stirring device to form a polyethylene terephthalate spinning solution with a concentration of 10 wt % to 30 wt %;

[0018] A polyethylene glycol phase change material having a weight average molecular weight of 600 to 6000 Da and 10% to 60% of the mass of the polyethylene terephthalate and having a weight average molecular weight of 600 to 6000 Da is added to the polyethylene terephthalate spinning solution, and the mixture is stirred for 8 hours and then allowed to stand for 2 hours to obtain an inner core layer spinning solution.

[0019] Preferably, the specific steps of preparing the nanofibers by using electrospinning coaxial spinning technology are as follows:

[0020] The outer skin layer spinning solution and the inner core layer spinning solution were respectively loaded into 5 ml plastic syringes, and the ends of the plastic syringes were connected to stainless steel electrospinning dies with an inner diameter of 0.84 mm and an outer diameter of 1.22 mm, respectively;

[0021] Set the stainless steel electrospinning voltage to 15kV to 25kV, the outer skin layer propulsion speed to 0.0010mm / s to 0.0030mm / s, the inner core layer propulsion speed to 0.0005mm / s to 0.0020mm / s, the receiving distance to 15cm to 20cm, the spinning time to 1 hour to 3 hours, the spinning temperature to 20℃ to 30℃, and the humidity to be controlled between 20% and 40%;

[0022] The obtained nanofiber samples were collected by an equipped collection device.

[0023] Preferably, the specific steps of the drying process are as follows:

[0024] The nanofiber sample is taken out from the collecting device and dried in a vacuum drying oven at a temperature of 60° C. to 80° C. to obtain a bifunctional polyethylene terephthalate sheath-core nanofiber.

[0025] The present invention provides a bifunctional polyethylene terephthalate sheath-core nano-micron fiber structure. It has the following beneficial effects:

[0026] 1. The present invention adopts electrospinning coaxial spinning technology to dissolve polyethylene terephthalate and polyethylene glycol phase change materials in hexafluoroisopropanol to prepare the inner core layer spinning solution. Compared with the traditional technology of encapsulating to below 500nm, this method does not need to be separately encapsulated before use, simplifies the process and does not require size control, has stable performance, and is suitable for large-scale production.

[0027] 2. The present invention organically combines the luminescent material with photoluminescence function and the temperature regulating material with phase change energy storage function through the structural design of the outer skin layer and the inner core layer of the polyethylene terephthalate nano-micron fiber, so that the polyethylene terephthalate nano-micron fiber has dual functions.

[0028] 3. The present invention uses phase change energy storage materials in the inner core layer to make the nanofiber have excellent temperature control performance. The fiber can effectively absorb and release heat, thereby regulating its own temperature when the ambient temperature changes, thereby improving the application range of the material in terms of comfort and environmental adaptability.

[0029] 4. The present invention retains the mechanical properties of the polyethylene terephthalate material itself while ensuring dual functions through the skin-core structure design, so that the fiber can not only meet the needs of photoluminescence scenarios such as fluorescent anti-counterfeiting and emergency warning, but also achieve human body temperature management through phase change energy storage. It is suitable for multiple fields such as smart wearable clothing, breaking through the application limitations of traditional single-function fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic cross-sectional view of a local structure of the inner core layer of a bifunctional polyethylene terephthalate sheath-core nano-micron fiber structure according to the present invention;

[0031] Figure 2 This is a flow chart of a method for preparing a bifunctional polyethylene terephthalate skin-core nano-micron fiber structure according to the present invention;

[0032] Figure 3 This is a SEM image of a bifunctional polyethylene terephthalate skin-core nano-micron fiber structure of the present invention;

[0033] Figure 4 This is a fluorescence spectrum of a bifunctional polyethylene terephthalate skin-core nano-micron fiber structure of the present invention;

[0034] Figure 5 This is a DSC curve diagram of a bifunctional polyethylene terephthalate skin-core nano-micron fiber structure of the present invention.

[0035] Among them, 1. Inner core layer; 2. Outer skin layer. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] Please see the attached Figure 1-Figure 5 An embodiment of the present invention provides a bifunctional polyethylene terephthalate sheath-core nano-micron fiber structure, comprising an inner core layer 1 and an outer skin layer 2. The inner core layer 1 is a composite of polyethylene terephthalate and a polyethylene glycol phase change material. The mass percentage of the polyethylene glycol phase change material to the polyethylene terephthalate is 10wt%~60wt%, and the molecular weight of the polyethylene glycol in the polyethylene glycol phase change material is 600~6000. The outer skin layer 2 is modified polyethylene terephthalate doped with a luminescent agent Eu(CA)3(Phen). The mass percentage of the polyethylene terephthalate and the luminescent agent Eu(CA)3(Phen) is 6wt%~12wt%. The outer skin layer 2 covers the inner core layer 1 to form a composite integral structure.

[0038] Specifically, the inner core layer 1 is composed of a composite of polyethylene terephthalate and polyethylene glycol phase change material, wherein polyethylene terephthalate has excellent mechanical properties and thermal stability, while polyethylene glycol phase change material has good fiber-forming property and biocompatibility. The composite of the two helps to improve the strength and flexibility of the inner core layer 1, while also improving its processing performance. The outer skin layer 2 is modified polyethylene terephthalate, doped with the luminescent agent Eu(CA)3 (Phen). The application of modified polyethylene terephthalate enhances the luminescent performance of the outer skin layer 2 while maintaining its excellent mechanical strength. Through the composite structure design, the luminescent material with photoluminescence function and the temperature regulating material with phase change energy storage function are organically combined, giving the prepared polyethylene terephthalate nanofiber dual functional characteristics, which not only improves the tensile strength and flexibility of the material, but also realizes the performance of photoluminescence and phase change energy storage.

[0039] The diameter of the inner core layer 1 ranges from 150 nm to 250 nm, and the thickness of the outer skin layer 2 ranges from 50 nm to 500 nm.

[0040] Specifically, the diameter range of the inner core layer 1 enables the nanofibers to have good microstructural properties, thereby increasing the specific surface area of ​​the material and enhancing the effective light absorption and heat conduction capabilities, while the thickness range of the outer skin layer 2 provides adaptability to achieve different physical property adjustments, thereby ensuring that the material has excellent mechanical strength and damage resistance. Through this specific diameter and thickness design, the comprehensive performance of the composite material can be optimized to meet the performance requirements in application fields such as smart textiles and sensors.

[0041] The outer skin layer 2 is coated with the inner core layer 1 by electrospinning coaxially to form an integrated organically combined and encapsulated structure.

[0042] Specifically, the outer skin layer 2 wraps the inner core layer 1 through electrospinning coaxial spinning to form an integrated organically combined encapsulated structure. The electrospinning coaxial spinning technology can control the thickness relationship between the inner core layer 1 and the outer skin layer 2 to ensure the formation of a uniform integrated organically combined encapsulated structure, thereby improving the mechanical properties and chemical stability of the material. At the same time, it helps to enhance the bonding force between the inner and outer layers and reduce the risk of interlayer delamination to adapt to different application requirements and improve the functionality and reliability of the overall material.

[0043] A method for preparing a bifunctional polyethylene terephthalate skin-core nano-micron fiber structure, the method comprising the following steps:

[0044] preparing a spinning solution for the outer skin layer 2, wherein the spinning solution for the outer skin layer 2 is composed of polyethylene terephthalate and a luminescent agent Eu(CA)3(Phen);

[0045] Prepare a spinning solution for the inner core layer 1, wherein the spinning solution for the inner core layer 1 is composed of polyethylene terephthalate and a polyethylene glycol phase change material;

[0046] The outer skin layer 2 spinning solution and the inner core layer 1 spinning solution are prepared into nanofibers by electrospinning coaxial spinning technology;

[0047] The obtained nanofibers are dried to obtain bifunctional polyethylene terephthalate sheath-core nano-micron fibers;

[0048] Specifically, the spinning solution of the outer skin layer 2 is composed of polyethylene terephthalate and the luminescent agent Eu(CA)3(Phen), ensuring that the luminescent agent Eu(CA)3(Phen) can be evenly dispersed in the polyethylene terephthalate, thereby improving the photoluminescent performance of the outer skin layer 2, achieving excellent luminescent properties in the material, and meeting the optical performance requirements of specific applications;

[0049] The spinning solution of the inner core layer 1 is composed of polyethylene terephthalate and polyethylene glycol phase change material. The introduction of the polyethylene glycol phase change material provides the inner core layer 1 with good thermal management function, which can realize phase change energy storage, so that the material has corresponding adjustment ability in the environment of temperature change, and improves the practical application effect of the material;

[0050] The nanofibers are made by electrospinning coaxially to control the thickness of the inner core layer 1 and the outer skin layer 2, thereby improving the bonding strength and uniformity of the composite material, generating a well-defined nanofiber structure, and improving the damage resistance and overall performance of the material;

[0051] The obtained nanofibers are dried to remove the solvent to ensure the stability of the fibers. The dried fibers can maintain good physical and chemical properties.

[0052] Through the above steps, the surface properties and adhesion of the final product are improved, while the photoluminescence and thermal management properties are improved, and the applicability and reliability of the material are enhanced.

[0053] The specific steps for preparing the outer skin layer 2 spinning solution are as follows:

[0054] The luminescent agent Eu(CA)3(Phen) and polyethylene terephthalate are placed in a vacuum drying oven and heated to 60°C to 80°C to remove moisture. 1g to 3g of dry polyethylene terephthalate is weighed and added to 5.0ml to 6.0ml of hexafluoroisopropanol. The mixture is stirred continuously at room temperature using a magnetic stirring device for 6 to 8 hours to form a polyethylene terephthalate spinning solution with a concentration of 10wt% to 30wt%.

[0055] 6 wt % to 12 wt % of Eu(CA)3(Phen) based on the mass of polyethylene terephthalate was added to the polyethylene terephthalate spinning solution, and the mixture was stirred for 8 hours and then allowed to stand for 2 hours to obtain a sheath layer 2 spinning solution.

[0056] Specifically, first, the luminescent agent Eu(CA)3(Phen) and polyethylene terephthalate are placed in a vacuum drying oven to remove moisture, ensure the uniformity and compatibility of the materials, and avoid moisture interfering with subsequent processing, thereby improving the dispersion effect of the luminescent agent and the polymer. Secondly, the dry polyethylene terephthalate is weighed and added to hexafluoroisopropanol, and continuously stirred with a magnetic stirring device at room temperature to form a polyethylene terephthalate spinning solution. Subsequently, Eu(CA)3(Phen) is added to the polyethylene terephthalate spinning solution, and the luminescent agent is ensured to be uniformly distributed by mixing, thereby enhancing the photoluminescent properties of the fiber and improving the functionality of the material to meet specific application requirements. Finally, the stirring is continued and then allowed to stand to ensure that all components are fully mixed and foam and impurities are eliminated, thereby improving the stability and uniformity of the solution, avoiding uneven material structure during the spinning process, and ensuring high-quality fiber molding. The resulting outer skin layer 2 spinning solution has good uniformity, compatibility and luminescent properties, which helps to improve the optical properties and structural stability of the nanofibers in practical applications.

[0057] Through the above steps, the polyethylene glycol phase change material and polyethylene terephthalate are dissolved together in hexafluoroisopropanol to prepare the inner core layer spinning solution through the electrospinning coaxial spinning technology. There is no need to encapsulate them separately. Compared with the encapsulation step in the traditional process, there is no need to strictly control the size of the phase change material, which simplifies the preparation process and reduces the process difficulty. At the same time, it ensures the stable presence of the phase change material in the core layer, effectively avoiding the leakage problem during the phase change process.

[0058] The specific steps for preparing the inner core layer 1 spinning solution are as follows:

[0059] 1 g to 3 g of dry polyethylene terephthalate is added to 5.0 ml to 6.0 ml of hexafluoroisopropanol, and stirred continuously for 6 to 8 hours at room temperature using a magnetic stirring device to form a polyethylene terephthalate spinning solution with a concentration of 10 wt % to 30 wt %;

[0060] A polyethylene glycol phase change material having a weight average molecular weight of 600 to 6000 Da and 10% to 60% of the mass of polyethylene terephthalate and having a weight average molecular weight of 600 to 6000 Da was added to the polyethylene terephthalate spinning solution, and the mixture was stirred for 8 hours and then allowed to stand for 2 hours to obtain a spinning solution for the inner core layer 1.

[0061] Specifically, first, dry polyethylene terephthalate is added to hexafluoroisopropanol to form a polymer solution, hexafluoroisopropanol is used as a solvent to ensure that the polyethylene terephthalate is fully dissolved, and a magnetic stirring device is continuously stirred at room temperature to ensure that the polyethylene terephthalate is completely dissolved, improve the uniformity of the solution, reduce the problem of particle aggregation, and form a polyethylene terephthalate spinning solution. A polyethylene glycol phase change material is added to the spinning solution to enhance the thermal management ability of the inner core layer 1, wherein the polyethylene glycol phase change material The weight-average molecular weight can be selected as 600, 800, 1000, 1500, 2000, 3000, 4000, 5000, and 6000, so that the final product can effectively store and release heat in different temperature environments. Continuous stirring and then standing ensure that the phase change material is evenly dispersed and eliminates foam and impurities, improves the stability and uniformity of the solution, avoids the generation of uneven structure during the spinning process, and ensures the generation of high-quality nanofibers. The final inner core layer 1 spinning solution has good uniformity, appropriate concentration and enhanced thermal management capabilities.

[0062] The specific steps of making nanofibers using electrospinning coaxial spinning technology are as follows:

[0063] The outer skin layer 2 spinning solution and the inner core layer 1 spinning solution were respectively loaded into 5 ml plastic syringes, and the ends of the plastic syringes were connected to stainless steel electrospinning dies with an inner diameter of 0.84 mm and an outer diameter of 1.22 mm, respectively;

[0064] The stainless steel electrospinning voltage was set to 15 kV to 25 kV, the outer skin layer 2 advancing speed was 0.0010 mm / s to 0.0030 mm / s, the inner core layer 1 advancing speed was 0.0005 mm / s to 0.0020 mm / s, the receiving distance was set to 15 cm to 20 cm, the spinning time was 1 hour to 3 hours, the spinning temperature was 20°C to 30°C, and the humidity was controlled between 20% and 40%;

[0065] The obtained nanofiber samples were collected by an equipped collection device.

[0066] Specifically, first, the outer skin layer 2 spinning solution and the inner core layer 1 spinning solution are respectively loaded into 5ml plastic syringes to ensure that they can be used simultaneously during the spinning process, thereby realizing coaxial spinning, and effectively combining the outer skin layer 2 and the inner core layer 1 to form the required composite structure and function, and connecting the end of the plastic syringe to a stainless steel electrospinning die with an inner diameter of 0.84mm and an outer diameter of 1.22mm. The spinning solution is guided by the connecting die to ensure the precise delivery of the liquid and achieve the center-to-center opposition of the two layers to provide the necessary structure for the formation of nanofibers, and the voltage, propulsion speed, receiving distance, spinning time, spinning temperature and humidity of the stainless steel electrospinning equipment are set, and these parameters are adjusted to control the production process, thereby optimizing the spinning conditions, accurately controlling the diameter, morphology and structure of the fiber, and ensuring the production of nanofibers that meet specific performance requirements. The obtained nanofiber samples are collected by an equipped collection device to ensure the integrity and uniformity of the fiber during the collection process, and nanofibers with specific structural and performance requirements can be effectively prepared.

[0067] The specific steps of drying treatment are as follows:

[0068] The nanofiber sample is removed from the collecting device and dried in a vacuum drying oven at a temperature of 60° C. to 80° C. to obtain a bifunctional polyethylene terephthalate sheath-core nanofiber.

[0069] Specifically, the nanofiber sample is first removed from the collecting device. The purpose of this step is to separate the nanofibers that have completed spinning, prepare for the subsequent drying process, and help avoid contamination and damage of the sample. The nanofiber sample is placed in a vacuum drying oven for drying, and the vacuum environment is used to remove moisture from the sample, effectively preventing the influence of moisture on the structure and performance of the nanofiber, ensuring the stability of the fiber in subsequent applications, and obtaining a bifunctional polyethylene terephthalate sheath-core nanofiber.

[0070] Example 1

[0071] Preparation of the outer skin layer 2 spinning solution: The luminescent agent Eu(CA)3(Phen) and polyethylene terephthalate were placed in a vacuum drying oven and heated to 80°C to remove moisture. 1 g of dry polyethylene terephthalate was weighed and added to 6.0 ml of hexafluoroisopropanol. The mixture was stirred continuously for 6 hours using a magnetic stirring device at room temperature to form a polyethylene terephthalate spinning solution with a concentration of 10 wt%. Eu(CA)3(Phen) with a mass percentage of 9 wt% of the polyethylene terephthalate was added to the solution. The mixture was stirred for 8 hours and then allowed to stand for 2 hours to obtain the outer skin layer 2 spinning solution.

[0072] Preparation of the spinning solution for the inner core layer 1: Weigh 3 g of dry polyethylene terephthalate and add it to 5.0 ml of hexafluoroisopropanol. Stir it continuously for 6 hours using a magnetic stirring device at room temperature to form a polyethylene terephthalate spinning solution with a concentration of 40 wt%. Add a polyethylene glycol phase change material with a polyethylene terephthalate mass of 20% and a weight-average molecular weight of 600 Da to the solution. Stir it continuously for 8 hours and then let it stand for 2 hours to obtain the spinning solution for the inner core layer 1.

[0073] Electrospinning coaxial spinning: The outer skin layer 2 spinning solution and the inner core layer 1 spinning solution were respectively loaded into 5 ml plastic syringes, and the ends were connected to a stainless steel electrospinning die with an inner diameter of 0.84 mm and an outer diameter of 1.22 mm. The voltage was set to 20 kV, the outer skin layer 2 propulsion speed was 0.0030 mm / s, the inner core layer 1 propulsion speed was 0.0005 mm / s, the receiving distance was 20 cm, the spinning time was 1 hour, the spinning temperature was 30 ° C, and the humidity was 20%. The obtained nanofiber sample was collected by the equipped collection device.

[0074] Drying treatment: The nanofibers were removed from the collecting device and dried in a vacuum drying oven at 70° C. to obtain bifunctional polyethylene terephthalate sheath-core nanofibers.

[0075] Example 2

[0076] Preparation of the outer skin layer 2 spinning solution: The luminescent agent Eu(CA)3(Phen) and polyethylene terephthalate were placed in a vacuum drying oven and heated to 70°C to remove moisture. 2 g of dry polyethylene terephthalate was weighed and added to 5.0 ml of hexafluoroisopropanol. The mixture was stirred continuously for 7 hours using a magnetic stirring device at room temperature to form a polyethylene terephthalate spinning solution with a concentration of 20 wt%. Eu(CA)3(Phen) with a mass percentage of 12 wt% of the polyethylene terephthalate was added to the solution. The mixture was stirred for 8 hours and then allowed to stand for 2 hours to obtain the outer skin layer 2 spinning solution.

[0077] Preparation of the spinning solution for the inner core layer 1: Weigh 1 g of dry polyethylene terephthalate and add it to 6.0 ml of hexafluoroisopropanol. Stir it continuously for 7 hours using a magnetic stirring device at room temperature to form a polyethylene terephthalate spinning solution with a concentration of 10 wt%. Add a polyethylene glycol phase change material with a polyethylene terephthalate mass of 30% and a weight-average molecular weight of 3300 Da to the solution. Stir continuously for 8 hours and then let it stand for 2 hours to obtain the spinning solution for the inner core layer 1.

[0078] Coaxial Electrospinning: The spinning solutions for outer layer 2 and inner core layer 1 were separately loaded into 5ml plastic syringes, each connected to a stainless steel electrospinning die with an inner diameter of 0.84mm and an outer diameter of 1.22mm. The voltage was set at 25kV, a propulsion speed of 0.0010mm / s for outer layer 2, and 0.00125mm / s for inner core layer 1. The receiving distance was 15cm, the spinning time was 3 hours, the spinning temperature was 20°C, and the humidity was 40%. The resulting nanofiber sample was collected using a collection device.

[0079] Drying treatment: The nanofibers were removed from the collecting device and dried in a vacuum drying oven at 80° C. to obtain bifunctional polyethylene terephthalate sheath-core nanofibers.

[0080] Example 3

[0081] Preparation of the outer skin layer 2 spinning solution: The luminescent agent Eu(CA)3(Phen) and polyethylene terephthalate were placed in a vacuum drying oven and heated to 80°C to remove moisture. 3 g of dry polyethylene terephthalate was weighed and added to 5.5 ml of hexafluoroisopropanol. The mixture was stirred continuously for 8 hours using a magnetic stirring device at room temperature to form a polyethylene terephthalate spinning solution with a concentration of 20 wt%. Eu(CA)3(Phen) at a concentration of 6 wt% by mass of polyethylene terephthalate was added to the solution. The mixture was stirred for 8 hours and then allowed to stand for 2 hours to obtain the outer skin layer 2 spinning solution.

[0082] Preparation of the spinning solution for the inner core layer 1: Weigh 2 g of dry polyethylene terephthalate and add it to 6.0 ml of hexafluoroisopropanol. Stir continuously for 8 hours using a magnetic stirring device at room temperature to form a polyethylene terephthalate spinning solution with a concentration of 20 wt%. Add a polyethylene glycol phase change material with a polyethylene terephthalate mass of 10% and a weight-average molecular weight of 6000 Da to the solution. Stir continuously for 8 hours and then let it stand for 2 hours to obtain the spinning solution for the inner core layer 1.

[0083] Electrospinning coaxial spinning: The outer skin layer 2 spinning solution and the inner core layer 1 spinning solution were respectively loaded into 5 ml plastic syringes, and the ends were connected to a stainless steel electrospinning die with an inner diameter of 0.84 mm and an outer diameter of 1.22 mm. The voltage was set to 15 kV, the outer skin layer 2 propulsion speed was 0.0020 mm / s, the inner core layer 1 propulsion speed was 0.0020 mm / s, the receiving distance was 17.5 cm, the spinning time was 2 h, the spinning temperature was 25 ° C, and the humidity was 30%. The obtained nanofiber sample was collected by the equipped collection device.

[0084] Drying treatment: The nanofibers were removed from the collecting device and dried in a vacuum drying oven at 60° C. to obtain bifunctional polyethylene terephthalate sheath-core nanofibers.

[0085] Comparative Example 1

[0086] The only difference from Example 1 is that Eu (CA) 3 (Phen) was not added in the preparation of the outer skin layer 2 spinning solution.

[0087] Comparative Example 2

[0088] The only difference from Example 1 is that no polyethylene glycol phase change material is added in the preparation of the spinning solution of the inner core layer 1.

[0089] Comparative Example 3

[0090] The only difference from Example 1 is that Eu(CA)3(Phen) and polyethylene glycol phase change material are added to the same spinning solution at the same time, and homogeneous fibers are prepared by single-channel spinning instead of coaxial spinning.

[0091] Comparative Example 4

[0092] The only difference from Example 1 is that the luminescent agent Eu(CA)3(Phen) is added to the inner core layer 1 and the phase change material is added to the outer skin layer 2.

[0093] Test samples: nanofibers prepared in the above-mentioned examples and comparative examples.

[0094] Photoluminescence performance testing

[0095] Detection method: Use a model F-7000 fluorescence spectrophotometer for testing. The test conditions are an excitation wavelength of 395nm, a scanning range of 550-700nm, a slit width of 5nm, and a test temperature of 25°C. Record the fluorescence intensity of the sample at 615nm, which is the characteristic emission peak of Eu³⁺.

[0096] Refer to GB / T15619-1995 "Terms of Luminescent Materials".

[0097] Phase change energy storage performance testing

[0098] Detection method: Use DSC200F3 differential scanning calorimeter for testing. The test conditions are temperature range 20-80℃, heating rate 5℃ / min, record the phase change latent heat and phase change temperature range of the sample, and perform 10 temperature cycle tests at the same time, and record the phase change latent heat after the cycle.

[0099] Refer to GB / T25871-2010 "Test method for thermal storage performance of phase change materials"

[0100] Surface stability testing

[0101] Detection method: Use a SU8010 scanning electron microscope to observe the surface morphology of the sample after 10 cycles of 20-80°C temperature, and record whether there are any signs of phase change material leakage;

[0102] The sample was weighed before and after the cycle, and the weight loss rate was calculated using the following formula: weight loss rate = (weight before the cycle - weight after the cycle) / weight before the cycle × 100%.

[0103] Experimental Table 1

[0104] In the above test, three parallel tests were performed on each sample, and the test results were averaged. The test results are shown in Table 1.

[0105] Table 1: Performance test comparison table

[0106] sample Fluorescence intensity (au) Initial phase change latent heat (J / g) Latent heat of phase change after 10 cycles (J / g) Does it have dual functions? Example 1 8500 19 17 yes Example 2 8600 20 18 yes Example 3 8400 18 16 yes Comparative Example 1 0 19 17 Energy storage only Comparative Example 2 8450 0 0 Emitting light only Comparative Example 3 3200 9 6 Dual function mean difference Comparative Example 4 2100 10 7 Dual function mean difference

[0107] Experimental conclusion: Examples 1-3 organically combine the photoluminescent material and the phase change energy storage material through the reasonable structural design of the polyethylene terephthalate nano-micron fiber outer layer 2 and the inner core layer 1, and both have excellent photoluminescent properties. As shown in Table 1, the fluorescence intensity of Examples 1-3 is 8400-8600 a.u. and stable phase change energy storage performance. As shown in Table 1, the initial phase change latent heat of Examples 1-3 is 18-20 J / g, and it still maintains 16-18 J / g after 10 cycles. In terms of surface stability, after 10 temperature cycles, its surface is still smooth with no obvious leakage signs, and the weight loss rate is only 1.1%-1.3%, indicating that it has good stability and durability, and achieves a synergistic effect of dual functions.

[0108] Comparative Example 1 has only phase change energy storage performance but no photoluminescence performance because no luminescent agent is added; Comparative Example 2 has only photoluminescence performance but no phase change energy storage performance because no phase change material is added; Comparative Example 3 adopts mixed spinning instead of skin-core structure, which causes the luminescent agent and the phase change material to interfere with each other, resulting in poor photoluminescence performance and phase change energy storage performance, and a small amount of phase change material remains on the surface, with a weight loss rate of 8.5%; Comparative Example 4 interchanges the skin and core materials, and the luminescent agent is wrapped inside, resulting in a significant reduction in luminescence efficiency, reduced stability of the phase change material in the skin, poor dual functions, a rough surface, and signs of phase change material leakage, with a weight loss rate of 6.8%.

[0109] In summary, Examples 1-3, through reasonable structural design and necessary processing technology, make the PET nano-micron fibers have dual functions and stable performance, while the comparative examples cannot achieve this effect due to the lack of key materials, unreasonable structural design or failure to perform necessary processing, which fully demonstrates the effectiveness and superiority of the scheme adopted in the examples.

[0110] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A bifunctional polyethylene terephthalate core-skin nano-micron fiber structure, comprising an inner core layer (1) and an outer skin layer (2), characterized in that: The inner core layer (1) is composed of a composite of polyethylene terephthalate and a polyethylene glycol phase change material, wherein the mass percentage of the polyethylene glycol phase change material to the polyethylene terephthalate is 10wt%~60wt%, and the molecular weight of the polyethylene glycol in the polyethylene glycol phase change material is 600~6000. The outer skin layer (2) is modified polyethylene terephthalate doped with a luminescent agent Eu(CA)3(Phen), and the mass percentage of the polyethylene terephthalate and the luminescent agent Eu(CA)3(Phen) is 6wt%~12wt%. The outer skin layer (2) covers the inner core layer (1) to form a composite integral structure.

2. The bifunctional polyethylene terephthalate sheath-core nano-micron fiber structure according to claim 1, characterized in that: The diameter of the inner core layer (1) ranges from 150 nm to 250 nm, and the thickness of the outer skin layer (2) ranges from 50 nm to 500 nm.

3. The bifunctional polyethylene terephthalate sheath-core nano-micron fiber structure according to claim 1, characterized in that: The outer skin layer (2) covers the inner core layer (1) through electrostatic coaxial spinning to form an integrated organically combined, wrapped and encapsulated structure.

4. A method for preparing a bifunctional polyethylene terephthalate sheath-core nano-micron fiber structure, used for the bifunctional polyethylene terephthalate sheath-core nano-micron fiber structure according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: Preparing a spinning solution for the outer skin layer (2), wherein the spinning solution for the outer skin layer (2) is composed of polyethylene terephthalate and a luminescent agent Eu(CA)3(Phen); Preparing an inner core layer (1) spinning solution, wherein the inner core layer (1) spinning solution is composed of polyethylene terephthalate and a polyethylene glycol phase change material; The outer skin layer (2) spinning solution and the inner core layer (1) spinning solution are prepared into nanofibers by using electrospinning coaxial spinning technology; The obtained nanofiber is dried to obtain a bifunctional polyethylene terephthalate sheath-core nano-micron fiber.

5. The bifunctional polyethylene terephthalate sheath-core nano-micron fiber structure according to claim 4, characterized in that: The specific steps of preparing the spinning solution for the outer skin layer (2) are as follows: The luminescent agent Eu(CA)3(Phen) and polyethylene terephthalate are placed in a vacuum drying oven and heated to 60°C to 80°C to remove moisture. 1g to 3g of dry polyethylene terephthalate is weighed and added to 5.0ml to 6.0ml of hexafluoroisopropanol. The mixture is stirred continuously at room temperature using a magnetic stirring device for 6 to 8 hours to form a polyethylene terephthalate spinning solution with a concentration of 10wt% to 30wt%. Add 6 wt% to 12 wt% of Eu(CA)3(Phen) based on the mass of polyethylene terephthalate to the polyethylene terephthalate spinning solution, continue stirring for 8 hours, and then let it stand for 2 hours to obtain a spinning solution for the outer skin layer (2).

6. The bifunctional polyethylene terephthalate sheath-core nano-micron fiber structure according to claim 4, characterized in that: The specific steps of preparing the spinning solution of the inner core layer (1) are as follows: 1 g to 3 g of dry polyethylene terephthalate is added to 5.0 ml to 6.0 ml of hexafluoroisopropanol, and stirred continuously for 6 to 8 hours at room temperature using a magnetic stirring device to form a polyethylene terephthalate spinning solution with a concentration of 10 wt % to 30 wt %; A polyethylene glycol phase change material having a weight average molecular weight of 600 to 6000 Da and 10% to 60% of the mass of the polyethylene terephthalate and having a weight average molecular weight of 600 to 6000 Da is added to the polyethylene terephthalate spinning solution, and the mixture is stirred for 8 hours and then allowed to stand for 2 hours to obtain an inner core layer (1) spinning solution.

7. The bifunctional polyethylene terephthalate sheath-core nano-micron fiber structure according to claim 4, characterized in that: The specific steps of using electrospinning coaxial spinning technology to prepare nanofibers are as follows: The outer skin layer (2) spinning solution and the inner core layer (1) spinning solution are respectively loaded into 5 ml plastic syringes, and the ends of the plastic syringes are respectively connected to stainless steel electrospinning dies with an inner diameter of 0.84 mm and an outer diameter of 1.22 mm; The stainless steel electrospinning voltage is set to 15 kV to 25 kV, the outer skin layer (2) propulsion speed is 0.0010 mm / s to 0.0030 mm / s, the inner core layer (1) propulsion speed is 0.0005 mm / s to 0.0020 mm / s, the receiving distance is set to 15 cm to 20 cm, the spinning time is 1 hour to 3 hours, the spinning temperature is 20°C to 30°C, and the humidity is controlled between 20% and 40%; The obtained nanofiber samples were collected by an equipped collection device.

8. The bifunctional polyethylene terephthalate sheath-core nano-micron fiber structure according to claim 4, characterized in that: The specific steps of the drying process are as follows: The nanofiber sample is taken out from the collecting device and dried in a vacuum drying oven at a temperature of 60° C. to 80° C. to obtain a bifunctional polyethylene terephthalate sheath-core nanofiber.

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