Photo-initiated polymerization phase change microcapsule material as well as preparation method and application thereof

Abstract

The invention discloses a photo-initiation polymerization phase change microcapsule material as well as a preparation method and application thereof. The method comprises the following steps: mixing a core material and a wall material, and adding a photoinitiator to obtain an oil phase; adding a surfactant into deionized water, and fully stirring to obtain a water phase; slowly pouring the oil phase into the water phase, and homogenizing at a corresponding rotating speed by using a homogenizer to obtain a stable emulsion; and cooling the emulsion to a corresponding temperature, irradiating with an ultraviolet lamp, centrifuging, washing with deionized water, and drying in a drying oven to obtain the phase change microcapsule. The phase change microcapsule disclosed by the invention shows a clear core-shell structure, is in a regular circle shape, and has relatively high phase change enthalpy, relatively high initial thermal weight loss temperature, controllable particle size and negligible leakage rate. When the phase change microcapsule is added into the resin, the composite material shows obvious delayed temperature rise when being heated, and the phase change material has no obvious leakage, so that a good application prospect is provided for being widely applied to thermal forming and thermal management based on high polymer materials.

Description

Technical Field

[0001] This invention relates to the field of thermal management composite materials, specifically to a photo-initiated polymerized phase change microcapsule material, its preparation method, and its application. Background Technology

[0002] Phase change materials (PCMs) are a class of materials that can store and release large amounts of energy within a narrow temperature range by switching between solid and liquid states, thereby improving energy efficiency. They are widely used in building materials, battery temperature control, and textile temperature regulation. However, in most cases, the direct use of organic PCMs suffers from leakage problems, which limits their application in actual production. Microencapsulation technology encapsulates PCM core materials within a shell, achieving efficient encapsulation of the core material. This reduces the fluidity of PCMs in application scenarios, overcomes the leakage problem caused by phase changes during melting, and significantly improves the practicality of PCMs. Polymer materials are widely used in various fields, such as building materials, battery casings, and medical cold chain packaging, all of which have significant requirements for the thermal management of polymer materials. The processing temperature of most common polymer materials is 160℃ and above, and the processing involves certain shear forces. This requires PCM microcapsules to have high thermal stability and certain mechanical properties. Inorganic shell materials, such as silicon dioxide, titanium dioxide, and calcium carbonate, offer the advantage of rapid thermal conductivity, but their high stiffness makes them prone to breakage, unsuitable for polymer processing. Organic shell materials, such as polymethyl methacrylate, polystyrene, and 1,6-hexanediol diacrylate, have low glass transition temperatures; at higher temperatures, the wall material softens, leading to microcapsule rupture, thus also making them unsuitable for polymer processing. Therefore, it is essential to prepare phase change microcapsules with high toughness, high glass transition temperature, and good heat resistance.

[0003] The literature (Zhang Xuefei, Zhang Wei, Wang Chengyao, Yan Ting, Preparation and Characterization of Hexadecane-Melamine Urea-Formaldehyde Phase Change Microcapsules, Modern Chemical Industry, Vol. 45, No. 6, June 2025) reports the preparation of phase change microcapsules with hexadecane as the core material and melamine urea-formaldehyde resin as the wall material via in-situ polymerization. The phase change microcapsules prepared by this process are relatively regular spherical in shape and possess high phase change enthalpy (189.7 J / g), crystallization enthalpy (189.9 J / g), and encapsulation efficiency (84%). During the preparation process, the particle size increases with increasing emulsifier dosage. Comparison of the weight loss curves of the phase change microcapsules and hexadecane using TGA testing shows that the thermal weight loss of the phase change microcapsules is slightly slower than that of hexadecane, indicating that the wall material of the phase change microcapsules has a certain inhibitory effect on the decomposition and volatilization of the core material, significantly improving the thermal stability of the phase change microcapsules and indirectly demonstrating the protective effect of the microcapsule shell on the core material. However, its shortcomings are: (1) Formaldehyde release risk: Using formaldehyde as a raw material with a large proportion will cause environmental pollution during the preparation process. It is also difficult to remove residual formaldehyde in the obtained product, which will continue to pollute the surrounding environment. (2) Process complexity: The formulation and ingredients are complex, the operation steps are cumbersome, the reaction time is long, the pH needs to be adjusted many times during the reaction, and it is sensitive to pH. It requires high precision and is not suitable for large-scale industrial production. (3) Poor heat resistance: TGA results show that phase change microcapsules begin to lose thermal weight at around 125℃. This temperature is far lower than the processing temperature of most common resins and cannot be used for resin processing.

[0004] In recent years, phase change microcapsules, as a novel energy storage material, have attracted widespread attention due to their superior ability to immobilize phase change materials, large specific surface area, better chemical stability, and higher heat resistance. The excellent properties of phase change microcapsules demonstrate their enormous potential in energy storage and make them ideal fillers for the preparation of temperature-controlled composite materials. Therefore, developing a phase change microcapsule with high toughness, high glass transition temperature, good heat resistance, and suitability for polymer processing is of great significance. Summary of the Invention

[0005] In order to overcome the problems of poor heat resistance, limited mechanical properties, and complex preparation process of existing phase change microcapsule materials, the present invention aims to provide a phase change microcapsule material with excellent heat resistance, high toughness, high glass transition temperature, simple and rapid preparation process, and suitable for polymer material processing, as well as its preparation method and application.

[0006] This invention utilizes a suitable emulsifier to facilitate the migration of the wall material to the core material surface, forming an oil / oil / water emulsion. The core-shell structure is then fixed using ultraviolet light to prepare phase change microcapsules. This preparation method is simple, efficient, environmentally friendly, and suitable for mass industrial production. Acrylic ester polymers, known for their good toughness, low shrinkage, and high glass transition temperature (GTH), are used as the shells of the phase change microcapsules. The GTH can reach 180°C, meeting the processing requirements of many common polymer materials. Encapsulating n-alkanes within the acrylate provides significant fixation and protection for the core material. Compared to directly adding phase change materials to the substrate, the substrate with added phase change microcapsules exhibits significantly higher raw material utilization and less leakage, making it promising for widespread application in polymer-based temperature storage and thermal management.

[0007] The objective of this invention is achieved through the following technical solutions.

[0008] A method for preparing photo-initiated polymerization phase change microcapsule material includes the following steps:

[0009] Using a heating stage, the core material and wall material are mixed in a specific ratio at a certain temperature, and a photoinitiator is added to obtain an oil phase. Then, using an oil bath, a surfactant is added to deionized water at a specific temperature and stirred thoroughly to obtain an aqueous phase. The oil phase is slowly poured into the aqueous phase, and homogenized using a homogenizer at the appropriate speed to obtain a stable emulsion. After cooling the emulsion to the appropriate temperature, it is irradiated with ultraviolet light, centrifuged, washed three times with deionized water, and dried in an oven to obtain phase change microcapsules.

[0010] Preferably, the mass ratio of the core material to the wall material is 1:0.1 to 1; more preferably, the mass ratio of the core material to the wall material is 1:1 to 0.6.

[0011] Preferably, the mass ratio of the core material to the surfactant is 1:0.05 to 0.2; more preferably, the mass ratio of the core material to the surfactant is 1:0.18.

[0012] Preferably, the mass ratio of the core material to deionized water is 1:20 to 60; more preferably, the mass ratio of the core material to deionized water is 1:30.

[0013] Preferably, the mass ratio of the core material to the photoinitiator is 1:0.05 to 0.5; more preferably, the mass ratio of the core material to the photoinitiator is 1:0.3.

[0014] Preferably, the alkane is at least one selected from paraffin, n-hexadecane, n-octadecane, n-docosane, and n-octadecane; more preferably, the alkane is n-docosane.

[0015] Preferably, the acrylate is at least one selected from 1,6-hexanediol diacrylate, methyl methacrylate, tricyclodecanediethanol diacrylate, and butyl acrylate; more preferably, the acrylate is tricyclodecanediethanol diacrylate.

[0016] Preferably, the photoinitiator is at least one of 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, benzoin, benzoin ether, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; more preferably, the photoinitiator is 2-hydroxy-2-methylphenylacetone.

[0017] Preferably, the surfactant is at least one of polyvinyl alcohol, Tween 80, Span 80, Triton X-100, and gum arabic; more preferably, the surfactant is a mixture of polyvinyl alcohol and Tween 80 in a ratio of 5:4.

[0018] Preferably, the temperature of the heating platform is 20-100℃ and the heating time is 0.5-3h; more preferably, the temperature of the heating platform is 75℃ and the heating time is 0.5h.

[0019] Preferably, the oil bath is heated at a temperature of 60-120°C for 0.5-3 hours; more preferably, the oil bath is heated at a temperature of 90°C for 0.5 hours.

[0020] Preferably, the homogenizer speed is 5000-20000 RPM; more preferably, the homogenizer speed is 10000 RPM.

[0021] Preferably, the illumination time of the ultraviolet lamp is 5-20 minutes; more preferably, the illumination time of the ultraviolet lamp is 15 minutes.

[0022] The photo-initiated polymerized phase change microcapsule material prepared by the above-described preparation method exhibits a clear core-shell structure, is regularly spherical, and has a high phase change enthalpy, a high initial thermal weight loss temperature, a controllable particle size, and a negligible leakage rate.

[0023] The above describes the application of a photo-initiated polymerized phase change microcapsule material. Due to its excellent toughness, high glass transition temperature, good heat resistance, controllable particle size, high enthalpy, and encapsulation rate, this phase change microcapsule material shows promising application prospects in temperature-controlled building materials, battery temperature management, medical cold chain packaging, and textile temperature regulation.

[0024] This invention uses acrylate polymers, which possess good toughness, low shrinkage, and high glass transition temperature, as the shell material for phase change microcapsules. These polymers not only have a high glass transition temperature but also good toughness and heat resistance, making the microcapsules more suitable for processing polymer materials. Furthermore, the acrylate polymer molecules contain acrylate groups (-O-CO-CH=CH2), exhibiting strong polarity, while n-dodecane is nonpolar. This facilitates the gradual migration of the shell material to the core material surface, effectively overcoming the drawbacks of traditional solvent evaporation methods for preparing phase change microcapsules, such as long preparation time and environmental unfriendliness.

[0025] Compared with the prior art, the present invention has the following advantages and technical effects:

[0026] (1) The present invention uses acrylate with good toughness, low shrinkage and high glass transition temperature as the shell of phase change microcapsules. Its glass transition temperature can reach 180°C, so that the phase change microcapsules meet the processing requirements of common polymer materials.

[0027] (2) This invention selects a suitable emulsifier to allow the wall material to migrate to the surface of the core material, forming an oil / oil / water emulsion, and then fixes the core-shell structure by ultraviolet light. It has the characteristics of being fast, efficient, environmentally friendly and suitable for mass industrial production.

[0028] (3) This invention prepares phase change microcapsules with high toughness, high glass transition temperature, good heat resistance and suitable for polymer material processing. For the first time, phase change microcapsule technology has been successfully applied to the processing of polymer materials, which greatly expands the application scenarios of phase change microcapsules.

[0029] (4) The method for preparing photo-initiated polymer phase change microcapsule materials of the present invention has a stable process, the formula is easy to obtain, and it is suitable for large-scale industrial production and application. Attached Figure Description

[0030] Figure 1 Differential scanning calorimetry (DSC) results for the photo-initiated polymerized phase change microcapsule material and n-dodecane in Examples 1-4 are shown.

[0031] Figure 2 The images show the TGA diagrams of the photo-initiated polymerized phase change microcapsule materials in Examples 1-4, n-dodecane, and the photo-initiated polymerized phase change microcapsule materials in the comparative examples.

[0032] Figure 3 The particle size distribution diagrams are for the photo-induced phase change microcapsule materials in 1, 5 to 7.

[0033] Figure 4 This is a scanning electron microscope image of the photo-initiated polymerization phase change microcapsule material in Example 1.

[0034] Figure 5This is a leakage test diagram of the photo-initiated polymerization phase change microcapsule material in Example 1.

[0035] Figure 6 Infrared thermal images of the photo-initiated polymerization phase change microcapsule material in Example 4, as well as the blank comparative example and the n-dodecane comparative example, applied to polymer material processing.

[0036] Figure 7 Temperature curves of the photo-initiated polymerization phase change microcapsule material in Example 4, as well as the blank comparative example and the n-dodecane comparative example, applied to polymer material processing.

[0037] Figure 8 The image shows a comparison of leakage in the photo-initiated polymerization phase change microcapsule material of Example 4, as well as the blank control and n-dodecane control, when applied to polymer material processing. Detailed Implementation

[0038] The following detailed description, in conjunction with examples and accompanying drawings, further illustrates specific embodiments of the present invention, but the implementation of the present invention is not limited thereto. It should be noted that any processes not specifically described below are those that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are considered to be conventional products that can be purchased commercially.

[0039] Example 1

[0040] Preparation of a photoinitiated polymerized phase change microcapsule material: 1g of n-dodecane and 1g of DCPDA were mixed, and 0.3g of 2-hydroxy-2-methylphenylacetone was added. The mixture was stirred at 75°C for 30 min to fully mix the oil phase. Then, 0.1g of PVA and 0.08g of Tween 80 were added to 30g of deionized water, and the mixture was stirred at 90°C for 30 min to obtain an aqueous phase. The oil phase was slowly poured into the aqueous phase, and homogenized using a homogenizer at 10000 RPM to obtain a stable emulsion. After cooling the emulsion to 50°C, it was irradiated with ultraviolet light for 20 min, centrifuged, washed three times with deionized water, and dried in a 55°C oven to obtain a white powder. The product was placed on both sides with a layer of filter paper and baked at 80°C for 1 h to completely remove the residual core material on the surface, thus obtaining a photoinitiated polymerized phase change microcapsule material (denoted as MPCM1).

[0041] Example 2

[0042] Preparation of a photoinitiated polymerized phase change microcapsule material: 1 g of n-dodecane and 0.8 g of DCPDA were mixed, and 0.3 g of 2-hydroxy-2-methylphenylacetone was added. The mixture was stirred at 75 °C for 30 min to fully mix the oil phase. Then, 0.1 g of PVA and 0.08 g of Tween 80 were added to 30 g of deionized water, and the mixture was stirred at 90 °C for 30 min to obtain an aqueous phase. The oil phase was slowly poured into the aqueous phase, and homogenized using a homogenizer at 10000 RPM to obtain a stable emulsion. After cooling the emulsion to 50 °C, it was irradiated with ultraviolet light for 20 min, centrifuged, washed three times with deionized water, and dried in a 55 °C oven to obtain a white powder. The product was then placed on both sides with a layer of filter paper and baked at 80 °C for 1 h to completely remove the residual core material on the surface, thus obtaining a photoinitiated polymerized phase change microcapsule material (denoted as MPCM2).

[0043] Example 3

[0044] Preparation of a photoinitiated polymerized phase change microcapsule material: 1 g of n-dodecane and 0.7 g of DCPDA were mixed, and 0.3 g of 2-hydroxy-2-methylphenylacetone was added. The mixture was stirred at 75 °C for 30 min to fully mix the oil phase. Then, 0.1 g of PVA and 0.08 g of Tween 80 were added to 30 g of deionized water, and the mixture was stirred at 90 °C for 30 min to obtain an aqueous phase. The oil phase was slowly poured into the aqueous phase, and homogenized using a homogenizer at 10000 RPM to obtain a stable emulsion. After cooling the emulsion to 50 °C, it was irradiated with ultraviolet light for 20 min, centrifuged, washed three times with deionized water, and dried in a 55 °C oven to obtain a white powder. The product was then placed on both sides with a layer of filter paper and baked at 80 °C for 1 h to completely remove the residual core material on the surface, thus obtaining a photoinitiated polymerized phase change microcapsule material (denoted as MPCM3).

[0045] Example 4

[0046] Preparation of a photoinitiated polymerized phase change microcapsule material: 1 g of n-dodecane and 0.6 g of DCPDA were mixed, and 0.3 g of 2-hydroxy-2-methylphenylacetone was added. The mixture was stirred at 75 °C for 30 min to fully mix the oil phase. Then, 0.1 g of PVA and 0.08 g of Tween 80 were added to 30 g of deionized water, and the mixture was stirred at 90 °C for 30 min to obtain an aqueous phase. The oil phase was slowly poured into the aqueous phase, and homogenized using a homogenizer at 10000 RPM to obtain a stable emulsion. After cooling the emulsion to 50 °C, it was irradiated with ultraviolet light for 20 min, centrifuged, washed three times with deionized water, and dried in a 55 °C oven to obtain a white powder. The product was then placed on both sides with a layer of filter paper and baked at 80 °C for 1 h to completely remove the residual core material on the surface, thus obtaining a photoinitiated polymerized phase change microcapsule material (denoted as MPCM4).

[0047] Example 5

[0048] Preparation of a photoinitiated polymerized phase change microcapsule material: 1g of n-dodecane and 1g of DCPDA were mixed, and 0.3g of 2-hydroxy-2-methylphenylacetone was added. The mixture was stirred at 75°C for 30 min to fully mix the oil phase. Then, 0.1g of PVA and 0.08g of Tween 80 were added to 30g of deionized water, and the mixture was stirred at 90°C for 30 min to obtain an aqueous phase. The oil phase was slowly poured into the aqueous phase, and homogenized using a homogenizer at 5000 RPM to obtain a stable emulsion. After cooling the emulsion to 50°C, it was irradiated with ultraviolet light for 20 min, centrifuged, washed three times with deionized water, and dried in a 55°C oven to obtain a white powder. The product was then placed on both sides with a layer of filter paper and baked at 80°C for 1 h to completely remove the residual core material on the surface, thus obtaining a photoinitiated polymerized phase change microcapsule material (denoted as MPCM5).

[0049] Example 6

[0050] Preparation of a photoinitiated polymerized phase change microcapsule material: 1g of n-dodecane and 1g of DCPDA were mixed, and 0.3g of 2-hydroxy-2-methylphenylacetone was added. The mixture was stirred at 75°C for 30 min to fully mix the oil phase. Then, 0.1g of PVA and 0.08g of Tween 80 were added to 30g of deionized water, and the mixture was stirred at 90°C for 30 min to obtain an aqueous phase. The oil phase was slowly poured into the aqueous phase, and homogenized using a homogenizer at 15000 RPM to obtain a stable emulsion. After cooling the emulsion to 50°C, it was irradiated with ultraviolet light for 20 min, centrifuged, washed three times with deionized water, and dried in a 55°C oven to obtain a white powder. The product was then placed on both sides with a layer of filter paper and baked at 80°C for 1 h to completely remove the residual core material on the surface, thus obtaining a photoinitiated polymerized phase change microcapsule material (denoted as MPCM6).

[0051] Example 7

[0052] Preparation of a photoinitiated polymerized phase change microcapsule material: 1g of n-dodecane and 1g of DCPDA were mixed, and 0.3g of 2-hydroxy-2-methylphenylacetone was added. The mixture was stirred at 75°C for 30 min to fully mix the oil phase. Then, 0.1g of PVA and 0.08g of Tween 80 were added to 30g of deionized water, and the mixture was stirred at 90°C for 30 min to obtain an aqueous phase. The oil phase was slowly poured into the aqueous phase, and homogenized using a homogenizer at 20000 RPM to obtain a stable emulsion. After cooling the emulsion to 50°C, it was irradiated with ultraviolet light for 20 min, centrifuged, washed three times with deionized water, and dried in a 55°C oven to obtain a white powder. The product was then placed on both sides with a layer of filter paper and baked at 80°C for 1 h to completely remove the residual core material on the surface, thus obtaining a photoinitiated polymerized phase change microcapsule material (denoted as MPCM7).

[0053] Comparative example:

[0054] Preparation of a photoinitiated polymerized phase change microcapsule material: 1g of DCPDA was placed in a beaker, and 0.3g of 2-hydroxy-2-methylphenylacetone was added. The mixture was stirred at 75℃ for 30min to fully mix the oil phase. Then, 0.1g of PVA and 0.08g of Tween 80 were added to 30g of deionized water, and the mixture was stirred at 90℃ for 30min to obtain an aqueous phase. The oil phase was slowly poured into the aqueous phase, and homogenized using a homogenizer at 20000RPM to obtain a stable emulsion. After cooling the emulsion to 50℃, it was irradiated with ultraviolet light for 20min, centrifuged, washed three times with deionized water, and dried in a 55℃ oven to obtain a white powder. A layer of filter paper was placed on both the top and bottom of the product, and it was baked at 80℃ for 1h to completely remove the residual core material on the surface, thus obtaining a photoinitiated polymerized phase change microcapsule material (denoted as EM2204).

[0055] Performance testing:

[0056] (1) Thermal performance tests were conducted on the photo-induced phase change microcapsule materials in Examples 1-4 (Test procedure: Differential scanning calorimetry was used to characterize the thermal properties of n-dodecane and the phase change microcapsules. The samples were measured in a nitrogen atmosphere at a heating and cooling rate of 10 k / min within a range of 20°C to 100°C. Two heating cycles were performed during the experiment to eliminate the thermal history of the materials). The obtained DSC curves are shown below. Figure 1 As shown. The encapsulation rate (E) of the microcapsules is then calculated using the encapsulation rate calculation formula. c The theoretical mass fraction is calculated using the formula for the theoretical mass fraction of the core material. The packaging efficiency (E) is calculated using the packaging efficiency formula. P ).

[0057] The formula for calculating the coverage rate is as follows: In the formula ΔHm This represents the enthalpy during the melting process, expressed in mW / mg.

[0058] The formula for calculating the theoretical quality score is as follows: Where m PCM and m DCPDA These represent the mass of the core material and the shell material, respectively, in grams.

[0059] The formula for calculating packaging efficiency is as follows:

[0060] The calculated encapsulation efficiency, theoretical mass fraction of core material, and encapsulation efficiency of the phase change microcapsules are shown in Table 1 below.

[0061] Table 1: Encapsulation efficiency, theoretical mass fraction of core material, and encapsulation efficiency of phase change microcapsules

[0062]

[0063] Depend on Figure 1 It can be seen that all MPCMs exhibit similar melting temperatures to n-dodecane. It is evident that the phase change temperature range of the phase change microcapsules is significantly wider than that of n-dodecane. This is because the lower thermal conductivity of the DCPDA shell hinders heat transfer to the core material. The enthalpies of melting for MPCM1-MPCM4 are 121.7 J / g, 133.0 J / g, 141.7 J / g, and 152.3 J / g, respectively. The enthalpies of melting and crystallization of the phase change microcapsules increase with increasing core-to-wall ratio, and the encapsulation degree also increases with increasing core-to-wall ratio. This is because the shell material in the phase change microcapsules has no thermal response at this temperature; therefore, the heat storage performance is mainly determined by the content of the core material. Table 1 shows that the theoretical mass fraction and encapsulation rate of the core material of the microcapsules are not significantly different. Furthermore, the Ec of the microcapsules is typically greater than φ. PCMs This is because during the polymerization process, a small portion of the wall material is not coated outside the core material, but instead undergoes self-polymerization within the emulsion, forming smaller nanoparticles. In summary, microcapsules exhibit excellent thermal properties, high enthalpy, high encapsulation efficiency, and high packaging efficiency.

[0064] (2) Thermal stability tests were conducted on the photo-initiated phase change microcapsule materials in Examples 1-4, the pure docosane material, and the photo-initiated phase change microcapsule material in the comparative example (test procedure: TGA testing of the samples was performed using a TG 209F3 instrument. 5-10 mg of sample was taken and heated from room temperature to 500°C at a heating rate of 20 kJ / min in a nitrogen flow of 20 ml / min. After treatment, the TGA curves of the samples were obtained). The obtained TGA curves are shown below. Figure 2 As shown.

[0065] Depend on Figure 2It is known that the thermal decomposition of n-docosahexanes occurs at 200℃-300℃, while the thermal decomposition of the control group EM2204 occurs at 375℃-490℃. The first stage of thermal decomposition of the phase change microcapsules exhibits similar characteristics to that of n-docosahexanes, representing the thermal decomposition of the core material. The second stage exhibits similar characteristics to EM2204, representing the thermal decomposition of the microcapsule shell material. The initial decomposition temperature of n-docosahexanes is around 200℃, while the initial decomposition temperature of the first stage of phase change microcapsules is around 215℃, with the core material decomposition temperature delayed by about 15℃, indicating that the wall material provides some protection to the shell material. The thermal decomposition of the core material precedes that of the shell material because the thermal decomposition of the core material is mainly caused by the evaporation of the core material. As the temperature increases, the pressure inside the microcapsule gradually increases, eventually leading to the rupture of the wall material, the evaporation of the core material, and the decomposition of the remaining wall material in the second stage. The first-stage weight loss rates of MPCM1-MPCM4 were 48.72%, 53.68%, 58.48%, and 65.53%, respectively, which are close to the actual encapsulation rate Ec of the microcapsules obtained by DSC test, which indirectly proves the reliability of the encapsulation.

[0066] (3) Particle size testing was performed on the photo-induced phase change microcapsule materials in Examples 1, 5-7 (Testing procedure: The particle size distribution of the microcapsules was analyzed using an LA-960 laser particle size analyzer. MPCMs were dispersed in water, a small amount of emulsifier was added, and the mixture was ultrasonically stirred to ensure uniform distribution before being added to the instrument for detection). Statistical analysis was performed on the obtained particle size, and the average particle size was calculated using Gaussian fitting. The relationship between particle size and homogenizer speed was obtained as follows: Figure 3 As shown.

[0067] Depend on Figure 3 The average diameters of the microcapsules prepared at 5000 rpm, 10000 rpm, 15000 rpm, and 20000 rpm were 16.36 μm, 7.27 μm, 4.36 μm, and 2.725 μm, respectively. It can be seen that the particle size of the microcapsules gradually decreases with increasing stirring speed, and the size distribution of the microcapsules becomes more concentrated. Smaller particle size results in a larger specific surface area and higher heat transfer efficiency. By changing the stirring speed, microcapsules of different sizes can be obtained, providing possibilities for various application scenarios.

[0068] (4) The photo-induced phase transition microcapsule material in Example 1 was subjected to scanning electron microscopy (SEM) testing. The composite material was characterized using a Quanta 200 environmental scanning electron microscope. The obtained SEM images are shown below. Figure 4 As shown.

[0069] Depend on Figure 4As can be seen, the microcapsules are regularly spherical, with smooth, defect-free surfaces and no core material residue. After rupturing the microcapsules through a certain treatment, it can be seen that the microcapsules have a clear core-shell structure, and the shell has a certain thickness, indicating that the DCPDA has successfully encapsulated n-dodecane.

[0070] (5) A leakage test was conducted on the photo-induced phase change microcapsule material in Example 1. The microcapsules were tested at 60°C using a constant-temperature magnetic stirrer, and the results were compared with those of n-dodecane. The leakage results are as follows: Figure 5 As shown.

[0071] Depend on Figure 5 It was found that n-dosane melted rapidly at 60°C, wetting the filter paper, while MPCM1 showed no significant change. When aqueous dye was added to the filter paper, due to the hydrophobic nature of n-dosane, the dye could not stain the filter paper containing n-dosane; instead, it condensed into water droplets on the surface. However, the filter paper containing MPCM1 was completely stained by the aqueous dye, indicating that MPCM1 leaked almost completely. This further proves that even after prolonged exposure to high temperatures, the microcapsules exhibit excellent sealing performance.

[0072] (6) The photo-induced phase change microcapsule material in Example 4 was subjected to polymer processing tests. 3.75g each of n-docosahexanes and MPCM4 were weighed and dried in an oven at 55°C for 24 hours. After cooling, they were weighed into sample bags. Using a mixer, n-docosahexanes and MPCM4 were respectively mixed with 21.25g of linear low-density polyethylene at 160°C for 10 minutes until homogeneous. A flat vulcanizing press was used to press the composite sheets. The 25g of linear low-density polyethylene was designated as sheet 1, the mixture of n-docosahexanes and linear low-density polyethylene as sheet 2, and the mixture of MPCM4 and linear low-density polyethylene as sheet 3. The hot-pressing temperature was 170°C, and the hot-pressing time was 8 minutes. The sheets were then cold-pressed in a cold press for 4 minutes to obtain the corresponding composite sheets. The composite sheets were analyzed in real-time using an MLX90640 infrared thermal imager. The infrared thermal image is shown below. Figure 6 As shown, the temperature curve is as follows Figure 7 As shown, the trays holding board 1, board 2, and board 3 are as follows: Figure 8 As shown.

[0073] Depend on Figure 6 It can be seen that, under the same time conditions, the temperature of the plate without any added phase change material is significantly higher than that of other plates with added phase change materials. This is because the phase change material absorbs heat during the phase change process, which delays the temperature rise of the plate. Under the same time conditions, the temperature of the plate with directly added n-dodecane is slightly higher than that of the plate with added phase change microcapsules, indicating that leakage of the phase change material directly added during processing occurs. In contrast, the shell of the phase change microcapsules can better fix the phase change material, improve the raw material utilization rate, and the phase change microcapsules can still function after plastic processing.

[0074] Depend on Figure 7 It can be seen that different types of boards exhibit significant temperature differences under the same heating conditions and for the same duration. At the same time, the temperature of boards without any added phase change materials is significantly higher than that of boards with added phase change materials. This is because the phase change materials absorb heat during the phase change process, thus delaying the temperature rise of the boards.

[0075] Depend on Figure 8 It can be seen that after the heating process, the exposed phase change material in plate 2 melts and gradually migrates to the plate surface, leading to significant leakage. Plate 3, however, shows almost no leakage, indicating that the microcapsules protect and fix the phase change material, and that the microcapsules retain good performance even after resin processing. This demonstrates that phase change microcapsules possess good toughness, a high glass transition temperature, and high heat resistance, and can play a temperature-controlling role after blending with polymer materials. In summary, the photo-initiated phase change microcapsule material obtained with a core-to-wall ratio of 1:0.6 (Example 4) exhibits the best performance: an enthalpy of 150.6 J / g, an encapsulation rate of 64.12%, an initial thermal weight loss temperature of 220.29℃, and a complete core-shell structure.

[0076] The above embodiments are merely preferred embodiments of the present invention and are only used to explain the present invention, not to limit the present invention. Any changes, substitutions, modifications, etc., made by those skilled in the art without departing from the spirit and essence of the present invention should be within the protection scope of the present invention.

Claims

1. A method for preparing photo-initiated polymerized phase change microcapsule materials, characterized in that, Photo-initiated polymerization, using alkane as the core material and acrylate as the wall material, includes the following steps: The core material and wall material are mixed, and a photoinitiator is added to obtain an oil phase. A surfactant is added to deionized water and stirred thoroughly to obtain an aqueous phase. The oil phase is slowly poured into the aqueous phase and homogenized using a homogenizer at the appropriate speed to obtain a stable emulsion. After the emulsion is cooled to the appropriate temperature, it is irradiated with ultraviolet light, centrifuged, washed with deionized water, and dried in an oven to obtain phase change microcapsules.

2. The method for preparing a photo-initiated polymerized phase change microcapsule material according to claim 1, characterized in that, The mass ratio of the core material to the wall material is 1:0.1 to 1; the mass ratio of the core material to the surfactant is 1:0.05 to 0.2; the mass ratio of the core material to deionized water is 1:20 to 60; and the mass ratio of the core material to the photoinitiator is 1:0.05 to 0.

5.

3. The method for preparing a photo-initiated polymerized phase change microcapsule material according to claim 1, characterized in that, The alkane is at least one of paraffin, n-hexadecane, n-octadecane, n-docosahexadecane, and n-octadecane.

4. The method for preparing a photo-initiated polymerized phase change microcapsule material according to claim 1, characterized in that, The acrylate is at least one of 1,6-hexanediol diacrylate, methyl methacrylate, tricyclodecanediethanol diacrylate, and butyl acrylate.

5. The method for preparing a photo-initiated polymerized phase change microcapsule material according to claim 1, characterized in that, The photoinitiator is at least one of 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, benzoin, benzoin ether, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

6. The method for preparing a photo-initiated polymerized phase change microcapsule material according to claim 1, characterized in that, The surfactant is at least one of polyvinyl alcohol, Tween 80, Span 80, Triton X-100, and gum arabic.

7. The method for preparing a photo-initiated polymerized phase change microcapsule material according to claim 1, characterized in that, The heating temperature for mixing the core material and the wall material is 20-100℃, and the heating time is 0.5-3h.

8. The method for preparing a photo-initiated polymerized phase change microcapsule material according to claim 1, characterized in that, The process of adding the surfactant to deionized water and stirring thoroughly to obtain an aqueous phase is carried out in an oil bath at a temperature of 60-120°C for 0.5-3 hours; the homogenizer speed is 5000-20000 RPM; and the UV lamp illumination time is 5-20 minutes.

9. A photoinitiated polymerization phase change microcapsule prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The structure is a core-shell structure, and the enthalpy of the microcapsule is (121.7 J / g-152.3 J / g), the coverage rate is (48.72%-65.53%), and the encapsulation efficiency is (100.1-103.5).

10. The application of the photo-initiated polymerized phase change microcapsule material of claim 9 in plastic processing, temperature-controlled building materials, battery temperature management, medical cold chain packaging, or textile temperature regulation.

Images