A composite phase change material and its preparation method and application

Abstract

The present invention relates to a composite phase-change material that improves the structural stability of the system, prevents liquid phase leakage, and enhances thermal conductivity, compensating for the low thermal conductivity of organic phase-change materials. Furthermore, the composite phase-change material of the present invention exhibits high heat storage density and strong temperature control capabilities, as well as efficient light-to-heat conversion and storage capabilities, and can be applied in the field of photothermal therapy. The present invention also relates to a method for preparing the composite phase-change material and its application.

Description

Technical Field

[0001] The present invention relates to the technical field of composite phase change heat storage materials, and in particular to a composite phase change material and a preparation method and application thereof. Background Art

[0002] Phase change heat storage, as a low-cost, green and efficient energy storage method, has been widely used in the fields of electronic product temperature control, low-energy buildings, waste heat recovery, aerospace, biomedicine and other fields. As one of the key materials for medium and low temperature phase change heat storage, organic phase change materials have attracted the attention of researchers due to their stable chemical properties, high heat storage density, small volume change, non-toxic and non-corrosive properties. Organic phase change materials store and release thermal energy through solid-liquid phase transitions, and common ones include paraffins, alkanes, polyols and fatty acids. However, organic phase change materials are prone to liquid phase leakage during the solid-liquid phase transition, resulting in system instability and low recycling efficiency. In addition, the defect of poor intrinsic thermal conductivity of the material greatly limits the efficient application of phase change materials.

[0003] Therefore, there is an urgent need to develop a new phase change material that can improve the structural stability of the system, prevent liquid leakage, and improve thermal conductivity. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a composite phase change material that can improve the structural stability of the system, prevent liquid phase leakage, and also improve thermal conductivity.

[0005] Another object of the present invention is to provide a method for preparing the composite phase change material.

[0006] Another object of the present invention is to provide an application of the above-mentioned composite phase change material in the field of photothermal therapy.

[0007] In order to achieve the above objectives, the present invention provides the following technical solutions.

[0008] In a first aspect, the present invention provides a composite phase change material, comprising: an aqueous binder-Mxene aerogel, wherein the aqueous binder-Mxene aerogel has a porous network structure, and the aqueous binder-Mxene aerogel comprises Mxene nanosheets and an aqueous binder for bonding the Mxene nanosheets; and

[0009] An organic phase change material is filled in the pores of the aqueous binder-MXene aerogel.

[0010] The present invention achieves a significant improvement in the thermal conductivity of the composite phase change material by efficiently compounding a high thermal conductivity three-dimensional porous network support material with an organic phase change material, and by leveraging the interaction between the pores and the phase change material and the continuous and rapid heat conduction pathways of the pores within the composite material. In addition, since the phase change material is filled in the pores of the network support structure, liquid phase leakage of the phase change material is prevented during the solid-liquid phase change process, thereby improving the structural stability of the composite phase change material and obtaining a high-performance composite phase change material.

[0011] The aqueous binder-MXene aerogel of the present invention is a porous network support material with high porosity and high thermal conductivity, which can effectively improve the overall performance of composite phase change materials and expand their applications. Pure MXene aerogel has poor mechanical properties. The addition of the aqueous binder can uniformly distribute the MXene nanosheets in the aqueous solution and enhance the bonding strength between the MXene nanosheets after freeze-drying, forming a continuous and stable three-dimensional porous network structure of the MXene aerogel. This enhances the strength and flexibility of the aerogel network and prevents structural collapse.

[0012] In addition, the composite phase change material of the present invention also has high heat storage density and excellent light-heat conversion and storage performance.

[0013] In some embodiments, the mass ratio of the MXene nanosheets, the aqueous binder, and the organic phase change material can be 10:(0.1-3):(15-90), for example, 10:(0.3-2.5):(17-90) or 10:(0.3-2.25):(17-90). Controlling the mass ratio of the MXene nanosheets, the aqueous binder, and the organic phase change material within the above range is conducive to obtaining a composite phase change material with high heat storage density, stable structure, high light-to-heat conversion and storage efficiency, and good temperature control performance. When the mass ratio of the three is not within the above range, liquid leakage during the phase change process, structural collapse, low heat storage density, and poor light-to-heat conversion and storage efficiency are likely to occur.

[0014] In some embodiments, the MXene nanosheets are few-layer or single-layer MXene nanosheets. Selecting few-layer or single-layer MXene nanosheets facilitates their uniform dispersion in aqueous solution and forms a low-density, high-porosity, three-dimensional continuous aerogel network structure after freeze-drying.

[0015] In some embodiments, the thermal conductivity of the composite phase change material is 0.35 to 1.07 W / (m·K), which is 150% to 500% higher than that of a single phase change material. The composite phase change material of the present invention has high thermal conductivity and can conduct heat quickly. In some specific embodiments, the thermal conductivity of the composite phase change material may be 0.35 W / (m·K), 0.4 W / (m·K), 0.45 W / (m·K), 0.5 W / (m·K), 0.55 W / (m·K), 0.6 W / (m·K), 0.65 W / (m·K), 0.7 W / (m·K), 0.75 W / (m·K), 0.8 W / (m·K), 0.85 W / (m·K), 0.9 W / (m·K), 0.95 W / (m·K), 1.0 W / (m·K), 1.05 W / (m·K) or 1.07 W / (m·K).

[0016] In some embodiments, the aqueous binder includes one or more of aqueous polyurethane, polyvinyl alcohol, polyvinyl acetate, aqueous acrylate, and aqueous chloroprene latex. The aqueous binder is selected to facilitate uniform dispersion of the MXene nanosheets in the solvent and complete removal of solvents such as water used in the preparation process during the freeze-drying process.

[0017] In some embodiments, the organic phase change material includes one or more of paraffin, octadecanoic acid, myristic acid, octadecanol, polyethylene glycol, octadecane, and tetradecane.

[0018] In a second aspect, the present invention provides a method for preparing a composite phase change material, comprising the following steps:

[0019] dissolving an aqueous binder in water to obtain an aqueous binder solution;

[0020] Dispersing MXene nanosheets in the mixed solution containing the aqueous binder, directionally freezing and then freeze-drying to obtain a three-dimensional ordered aqueous binder-MXene aerogel;

[0021] The aqueous binder-Mxene aerogel and the organic phase change material are vacuum melted to fill the pores of the aqueous binder-Mxene aerogel with the organic phase change material to obtain a composite phase change material.

[0022] The present invention uses two-dimensional transition metal MXene nanosheets as a skeleton and water-based polyurethane as a binder to form a three-dimensional ordered water-based binder-MXene aerogel support material with continuous high thermal conductivity pathways, lightweight porosity, and strong light absorption. The aerogel support material is then combined with an organic phase change material through vacuum melting technology to obtain a three-dimensional ordered water-based binder-MXene aerogel composite phase change material with high heat storage density, stable structure, rapid heat transfer, and excellent light-heat conversion and storage performance.

[0023] In some embodiments, the MXene nanosheets are uniformly dispersed in the aqueous binder solution by stirring in an ice-water bath and an inert atmosphere for 1-5 hours. Dispersing in an ice-water bath and an inert atmosphere can effectively prevent oxidation of the MXene nanosheets.

[0024] In some embodiments, the directional freezing is performed in a cold source at -78°C to -196°C. The cold source may be liquid nitrogen.

[0025] In some embodiments, the freeze-drying time is 2-60 hours. Controlling the freeze-drying time within the above range is conducive to completely removing water, thereby facilitating the formation of a three-dimensional continuous low-density, high-porosity MXene aerogel network structure. If the drying time is too short, it is not conducive to the formation of a three-dimensional continuous network structure and is prone to structural collapse.

[0026] In some embodiments, the vacuum melting is performed under vacuum conditions at 60-120°C. Through vacuum melting and infiltration, the organic phase change material is filled into the pores of the aqueous binder-MXene aerogel material, thereby achieving efficient composite bonding. However, the vacuum melting temperature is not limited to 60-120°C and can be adjusted according to the melting temperature of the organic phase change material used, as long as the organic phase change material can be melted.

[0027] In some embodiments, the MXene nanosheets can be prepared by a method comprising the following steps:

[0028] Lithium fluoride is dissolved in hydrochloric acid, titanium aluminum carbide powder is added, and the mixture is reacted under heating conditions to obtain a black suspension, which is then washed with water until neutral to obtain MXene particles;

[0029] The MXene particles are dispersed in water and repeatedly frozen and thawed, and then ultrasonically treated in an inert atmosphere. After centrifugation, the upper layer solution obtained is dried to obtain MXene nanosheets containing a few layers or a single layer.

[0030] In some specific embodiments, the preparation method of the MXene nanosheets includes: adding lithium fluoride (LiF) to a hydrochloric acid solution, stirring until the LiF is completely dissolved, adding titanium aluminum carbide powder, and heating to 35-40°C (such as 37°C), stirring and reacting for 12-48 hours to obtain a black suspension; washing the black suspension with deionized water until neutral, and the obtained black precipitate is MXene particles.

[0031] The MXene particles are dispersed in deionized water and repeatedly frozen and thawed 2-4 times. The thawed solution is then ultrasonically treated in an argon atmosphere for 10-60 minutes, and finally centrifuged at 3000-8000 rpm for 3-40 minutes. The upper layer solution obtained is dried to obtain a few-layer or single-layer MXene nanosheet.

[0032] In a third aspect, the present invention provides an application of the composite phase change material of the first aspect or the composite phase change material obtained by the preparation method of the second aspect in the field of photothermal therapy.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention provides a composite phase change material, which can improve the structural stability of the system, prevent liquid leakage, and at the same time improve thermal conductivity, thereby compensating for the low thermal conductivity of the original organic phase change material.

[0035] In addition, the composite phase change material of the present invention also has high heat storage density and strong temperature control performance (can be obtained from Figure 4 It can be seen) and also has efficient light-heat conversion and storage functions, and can be applied in the field of photothermal therapy.

[0036] 2. The present invention also provides a method for preparing a composite phase change material, which has a simple preparation process and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a scanning electron microscope image of the three-dimensional ordered waterborne polyurethane-Mxene aerogel of Example 1 of the present invention.

[0038] Figure 2 This is a scanning electron microscope image of the composite phase change material obtained in Example 1 of the present invention.

[0039] Figure 3 This is a DSC curve diagram of the composite phase change material obtained in Example 2 of the present invention.

[0040] Figure 4 This is a temperature-time curve diagram of the composite phase change material photothermal therapy application obtained in Example 2 of the present invention.

[0041] Figure 5 This is a scanning electron microscope image of the composite phase change material obtained in Comparative Example 1. DETAILED DESCRIPTION

[0042] The technical solutions of the present invention will be further described in detail below with reference to the following embodiments. It should be understood that the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0043] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which this invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments, and equipment used in the following examples are all commercially available or can be obtained through existing methods; the amounts of the experimental reagents used, unless otherwise specified, are the amounts used in conventional experimental procedures; and the experimental methods, unless otherwise specified, are all conventional methods.

[0044] Example 1

[0045] Step 1: Add 2.6 g of lithium fluoride (LiF) to 10 mL of hydrochloric acid solution, stir at high speed until LiF is completely dissolved, then add 2 g of titanium aluminum carbide powder, heat to 37 ° C, and continue stirring for 24 hours to obtain a black suspension; wash the black suspension with deionized water until neutral, and the obtained black precipitate is MXene particles.

[0046] Step 2: Disperse all the MXene particles obtained above in deionized water and freeze-thaw repeatedly three times. Then, ultrasonicate the thawed solution in an argon atmosphere for 30 minutes, and finally centrifuge it at 3500 rpm for 10 minutes. After drying, the upper layer solution obtained is a few-layer or single-layer MXene nanosheet.

[0047] Step 3: Add 10 mL of deionized water to 50 mg of aqueous polyurethane with a solid content of 45% to dilute it. Add 100 mg of MXene nanosheet powder to the diluted aqueous polyurethane solution. Stir in an argon atmosphere under ice-water bath conditions for 2 hours to evenly disperse the MXene nanosheets in the aqueous polyurethane solution. Then, use liquid nitrogen as a cold source and use directional freezing to quickly freeze the mixed solution. The frozen sample is freeze-dried for 24 hours to obtain a low-density, high-porosity three-dimensional ordered aqueous polyurethane-MXene aerogel. The scanning electron microscope image is shown below. Figure 1 shown.

[0048] Step 4: The three-dimensional ordered waterborne polyurethane-MXene aerogel obtained in step 3 was placed under vacuum conditions at 100°C and efficiently compounded with 900 mg of paraffin wax by vacuum melt infiltration to obtain a shaped composite phase change material with high thermal conductivity, high heat storage density, and efficient light-heat conversion and storage performance. The scanning electron microscope image is shown below. Figure 2 shown.

[0049] The mass fraction of the stable paraffin loading in the obtained composite phase change material is 88%, the melting enthalpy is 187 J / g (indicating a high heat storage density), the thermal conductivity of the composite material is 300% higher than that of paraffin, and the photothermal conversion and storage efficiency reaches 85%.

[0050] Example 2

[0051] Step 1: Add 2.6 g of lithium fluoride (LiF) to 50 mL of hydrochloric acid solution, stir at high speed until LiF is completely dissolved, then add 3 g of titanium aluminum carbide powder, heat to 37 ° C, and continue stirring for 36 hours to obtain a black suspension; the black suspension is washed with deionized water until neutral, and the obtained black precipitate is MXene particles.

[0052] Step 2: Disperse all the MXene particles obtained above in deionized water and freeze-thaw repeatedly three times. Then, ultrasonicate the thawed solution in an argon atmosphere for 40 minutes, and finally centrifuge it at 4000 rpm for 30 minutes. After drying, the upper layer solution obtained is a few-layer or single-layer MXene nanosheet.

[0053] Step 3: 20 mL of deionized water was added to 30 mg of aqueous polyurethane (45% solids content) for dilution. 200 mg of MXene nanosheet powder was then added to the diluted aqueous polyurethane solution. The mixture was stirred in an argon atmosphere in an ice-water bath for 3 hours to uniformly disperse the MXene nanosheets in the aqueous polyurethane solution. The mixed solution was then rapidly frozen using directional freezing with liquid nitrogen as a cooling source. The frozen sample was freeze-dried for 40 hours to obtain a low-density, high-porosity, three-dimensional ordered aqueous polyurethane-MXene aerogel.

[0054] Step 4: The three-dimensional ordered waterborne polyurethane-MXene aerogel obtained in step 3 was placed under vacuum conditions at 80°C and efficiently compounded with 950mg of polyethylene glycol by vacuum melt infiltration to obtain a shaped composite phase change material with high thermal conductivity, high heat storage density, and high efficiency of photothermal conversion and storage performance. The phase change enthalpy (phase change enthalpy, also known as heat storage density) curve was obtained by differential scanning calorimetry. Figure 3 shown.

[0055] The mass fraction of polyethylene glycol stable loading in the obtained composite phase change material is 93%, the melting enthalpy is 182 J / g, the thermal conductivity of the composite material is 250% higher than that of polyethylene glycol, and the light-heat conversion and storage efficiency reaches 87%.

[0056] The obtained composite phase change material was applied to a photothermal therapy eye mask. When the composite phase change material was filled into a commercial thermotherapy eye mask, a recyclable light-driven thermotherapy eye mask was obtained. By simulating the heating of the photothermal therapy eye mask under sunlight and then comparing it with the thermotherapy of a commercial eye mask, it was found that the thermotherapy eye mask encapsulated with the composite phase change material had a longer temperature control time and a more stable temperature control temperature. The actual temperature control temperature-time curve measured after wearing it on the human eye is shown in the figure below. Figure 4 As shown, the temperature can be continuously controlled at around 45°C and hyperthermia can be performed for 1900 seconds.

[0057] Example 3

[0058] Step 1: Add 2.6 g of lithium fluoride (LiF) to 80 mL of hydrochloric acid solution, stir at high speed until LiF is completely dissolved, then add 4 g of titanium aluminum carbide powder, heat to 37 ° C, and continue stirring for 48 hours to obtain a black suspension; wash the black suspension with deionized water until neutral, and the obtained black precipitate is MXene particles.

[0059] Step 2: Disperse all the MXene particles obtained above in deionized water and freeze-thaw repeatedly three times. Then, ultrasonicate the thawed solution in an argon atmosphere for 60 minutes, and finally centrifuge at 7000 rpm for 40 minutes. The upper layer solution obtained after drying is a few-layer or single-layer MXene nanosheet.

[0060] Step 3: 50 mg of waterborne polyurethane (45% solids content) was diluted with 50 mL of deionized water. 500 mg of MXene nanosheet powder was then added to the diluted solution. The mixture was stirred in an ice-water bath under argon atmosphere for 5 hours to uniformly disperse the MXene nanosheets in the waterborne polyurethane solution. The mixed solution was then rapidly frozen using directional freezing with liquid nitrogen as a cooling source. The frozen sample was freeze-dried for 60 hours to obtain a low-density, high-porosity, three-dimensional ordered waterborne polyurethane-MXene aerogel.

[0061] Step 4: The three-dimensional ordered waterborne polyurethane-Mxene aerogel obtained in step 3 is placed under vacuum conditions at 80°C, and efficiently compounded with 850 mg of tetradecanoic acid by vacuum melt infiltration to obtain a shaped composite phase change material with high thermal conductivity, high heat storage density, and efficient light-heat conversion and storage performance.

[0062] The mass fraction of the stable loading of tetradecanoic acid in the obtained composite phase change material is 85%, the melting enthalpy is 172 J / g, the thermal conductivity of the composite material is increased by 350% compared with tetradecanoic acid, and the photothermal conversion and storage efficiency reaches 86%.

[0063] Example 4

[0064] Step 1: Add 2.6 g of lithium fluoride (LiF) to 50 mL of hydrochloric acid solution, stir at high speed until LiF is completely dissolved, then add 3 g of titanium aluminum carbide powder, heat to 37 ° C, and continue stirring for 40 hours to obtain a black suspension; the black suspension is washed with deionized water until neutral, and the obtained black precipitate is MXene particles.

[0065] Step 2: Disperse all the MXene particles obtained above in deionized water and freeze-thaw repeatedly 4 times. Then, ultrasonicate the thawed solution in an argon atmosphere for 50 minutes, and finally centrifuge at 6000 rpm for 20 minutes. The upper layer solution obtained after drying is a few-layer or single-layer MXene nanosheet.

[0066] Step 3: 20 mg of aqueous polyurethane (45% solids content) was diluted with 30 mL of deionized water. 300 mg of MXene nanosheet powder was added to the diluted aqueous polyurethane solution. The mixture was stirred in an ice-water bath under argon atmosphere for 3 hours to uniformly disperse the MXene nanosheets in the aqueous polyurethane solution. The mixed solution was then rapidly frozen using directional freezing with liquid nitrogen as a cooling source. The frozen sample was freeze-dried for 40 hours to obtain a low-density, high-porosity, three-dimensional ordered aqueous polyurethane-MXene aerogel.

[0067] Step 4: The three-dimensional ordered waterborne polyurethane-Mxene aerogel obtained in step 3 is placed under vacuum conditions at 70°C, and efficiently compounded with 900 mg of octadecane by vacuum melt infiltration to obtain a shaped composite phase change material with high thermal conductivity, high heat storage density, and efficient light-heat conversion and storage performance.

[0068] The mass fraction of the stable loading of octadecane in the obtained composite phase change material is 91%, the melting enthalpy is 180 J / g, the thermal conductivity of the composite material is 320% higher than that of tetradecanoic acid, and the photothermal conversion and storage efficiency reaches 88%.

[0069] Example 5

[0070] Step 1: Add 2.6 g of lithium fluoride (LiF) to 15 mL of hydrochloric acid solution, stir at high speed until LiF is completely dissolved, then add 3.5 g of titanium aluminum carbide powder, heat to 37 ° C, and continue stirring for 48 hours to obtain a black suspension; the black suspension is washed with deionized water until neutral, and the obtained black precipitate is MXene particles.

[0071] Step 2: Disperse all the MXene particles obtained above in deionized water and freeze-thaw repeatedly 4 times. Then, ultrasonicate the thawed solution in an argon atmosphere for 50 minutes, and finally centrifuge at 5000 rpm for 35 minutes. The upper layer solution obtained after drying is a few-layer or single-layer MXene nanosheet.

[0072] Step 3: 20 mL of deionized water was added to 45 mg of aqueous polyurethane (45% solids content) for dilution. 200 mg of MXene nanosheet powder was then added to the diluted aqueous polyurethane solution. The mixture was stirred in an argon atmosphere in an ice-water bath for 2 hours to uniformly disperse the MXene nanosheets in the aqueous polyurethane solution. The mixed solution was then rapidly frozen using liquid nitrogen as a cooling source using a directional freezing method. The frozen sample was freeze-dried for 50 hours to obtain a low-density, high-porosity, three-dimensional ordered aqueous polyurethane-MXene aerogel.

[0073] Step 4: The three-dimensional ordered waterborne polyurethane-Mxene aerogel obtained in step 3 is placed under vacuum conditions at 60°C, and efficiently compounded with 900 mg of octadecyl alcohol by vacuum melt infiltration to obtain a shaped composite phase change material with high thermal conductivity, high heat storage density, and efficient light-heat conversion and storage performance.

[0074] The mass fraction of the stable loading of octadecyl alcohol in the obtained composite phase change material is 89%, the melting enthalpy is 192 J / g, the thermal conductivity of the composite material is 400% higher than that of tetradecanoic acid, and the photothermal conversion and storage efficiency reaches 87%.

[0075] Comparative Example 1

[0076] The method of Example 1 was followed, except that the directional freezing in step 3 was replaced by non-directional freezing. The scanning electron microscope image of the obtained composite phase change material is shown in FIG. Figure 5 The obtained comparative example composite phase change material has a stable paraffin loading mass fraction of 70%, a melting enthalpy of 132 J / g, a thermal conductivity of the composite material only 40% higher than that of paraffin, and a light-heat conversion and storage efficiency of 77%.

[0077] The foregoing description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be readily conceived by a person skilled in the art within the technical scope disclosed herein are intended to be encompassed within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A composite phase change material, characterized in that: include: A water-based binder-Mxene aerogel, wherein the water-based binder-Mxene aerogel has a porous network structure and is composed of Mxene nanosheets and a water-based binder for bonding the Mxene nanosheets; as well as An organic phase change material, wherein the organic phase change material is filled in the pores of the aqueous binder-MXene aerogel; the mass ratio of the MXene nanosheets, the aqueous binder, and the organic phase change material is 10:2.25:90; The aqueous binder is aqueous polyurethane; The organic phase change material is paraffin.

2. The composite phase change material according to claim 1, characterized in that: The MXene nanosheets are few-layer or single-layer MXene nanosheets.

3. A method for preparing the composite phase change material according to claim 1 or 2, characterized in that: The following steps are involved: dissolving an aqueous binder in water to obtain an aqueous binder solution; Dispersing MXene nanosheets in the aqueous binder solution, freeze-drying after directionally freezing, and obtaining a three-dimensional ordered aqueous binder-MXene aerogel; The aqueous binder-Mxene aerogel and the organic phase change material are vacuum melted to fill the pores of the aqueous binder-Mxene aerogel with the organic phase change material to obtain a composite phase change material.

4. The preparation method according to claim 3, characterized in that The mixture was stirred in an inert atmosphere under ice-water bath conditions for 1-5 hours to uniformly disperse the MXene nanosheets in the aqueous binder solution.

5. The preparation method according to claim 3 or 4, characterized in that The freeze-drying time is 2-60h.

6. Use of the composite phase change material according to claim 1 or 2 or the composite phase change material obtained by the preparation method according to any one of claims 3 to 5 in the field of photothermal therapy.

Images