A shape-stabilized phase change thermal storage material based on a biomimetic polymerization technique and a preparation method thereof

Abstract

The present application relates to a kind of phase change heat storage materials based on biomimetic polymerization technology and preparation method thereof.The present application first prepares copper hydroxide colloidal particle stable suspension, then forms polydopamine covering layer on the surface of copper oxide colloidal particle by biomimetic polymerization, then drops dilute hydrochloric acid into the suspension, makes copper hydroxide colloidal particle dissolve and release copper ions, and forms interconnected pores in polydopamine.On this basis, reducing agent is added to the solution, and copper ions are reduced to copper nanoparticles by simple in-situ reduction technology, obtaining copper nanoparticle-doped three-dimensional porous polydopamine, and then preparing high-load and high-thermal-conductivity shaped phase change heat storage materials with it as carrier.The phase change heat storage material of the present application has high energy storage density and good thermal conductivity, and can be used for solar energy storage and utilization, industrial waste heat utilization or building energy saving, and makes positive contribution to the realization of the important strategic goal of "carbon peak" and "carbon neutralization" of the country.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection and energy conservation, and in particular relates to a shape-stabilized phase change thermal storage material based on biomimetic polymerization technology and its preparation method. Technical Background

[0002] With rapid economic development, the energy shortage problem has become increasingly severe, and the development and utilization of renewable energy and the improvement of energy efficiency have become a global focus. Phase change materials have attracted increasing attention due to their advantages such as high energy density, reusability, and good stability, and are widely used in solar thermal systems, building energy conservation, and industrial waste heat utilization, playing an important role in carbon emission reduction.

[0003] Based on their chemical composition, phase change thermal energy storage materials (PCEs) can be divided into organic and inorganic categories. Among them, organic PCEs are currently the most promising PCEs due to their advantages such as good chemical and thermal stability, low price, and absence of phase separation. However, the direct use of organic PCEs suffers from problems such as low thermal conductivity and easy liquid phase leakage during the phase change process, limiting their widespread application. To address these issues, porous materials can be used as carriers to prepare shaped PCEs through methods such as physical adsorption, vacuum impregnation, and melt blending. To date, a large number of porous materials, including porous silicon, porous carbon, porous mineral materials, porous ceramics, and zeolite molecular sieves, have been applied to the preparation of shaped PCEs, yielding rich research results. However, the preparation of shaped PCEs using traditional porous materials as carriers still faces the following problems: ① low loading capacity leads to low energy density of the PCEs; ② poor thermal conductivity leads to low heat storage and release efficiency. These problems limit the widespread application of shaped PCEs. Summary of the Invention

[0004] To improve the loading capacity and thermal conductivity of shape-controlled phase change thermal storage materials, this invention first prepares a stable suspension of copper hydroxide colloidal particles. Then, through biomimetic polymerization, a polydopamine coating layer is formed on the surface of the copper hydroxide colloidal particles. Simultaneously, the polydopamine particles form a cross-linked three-dimensional network structure through polymerization. Next, dilute hydrochloric acid is added dropwise to the suspension, causing the copper hydroxide colloid to dissolve and release copper ions, forming interconnected channels within the polydopamine. Furthermore, due to the strong chelating effect of catechol in the polydopamine molecules on metal ions, copper ions can be fixed on its surface through adsorption, forming a uniform copper ion coating layer. Based on this, a reducing agent is added to the solution, and a simple in-situ reduction technique is used to reduce the copper ions to copper nanoparticles, obtaining copper nanoparticle-doped three-dimensional porous polydopamine. This polydopamine is then used as a carrier to prepare shape-controlled phase change thermal storage materials with high loading capacity and high thermal conductivity.

[0005] On one hand, the present invention provides a phase change thermal storage material based on biomimetic polymerization technology. The phase change thermal storage material is a shaped phase change thermal storage material doped with copper nanoparticles and containing three-dimensional porous polydopamine. By weight percentage, the phase change thermal storage material based on biomimetic polymerization technology comprises the following components:

[0006] Carrier 5%-40%

[0007] Shaped phase change thermal storage material core material 60%-95%

[0008] The carrier is nanoparticle-doped three-dimensional porous polydopamine; the core material of the shaped phase change thermal storage material is selected from stearic acid, myristic acid or polyethylene glycol, preferably stearic acid.

[0009] On the other hand, the present invention provides a method for preparing a phase change thermal storage material based on biomimetic polymerization technology, the preparation method comprising:

[0010] 1) Preparation of a stable suspension of copper hydroxide colloidal particles;

[0011] 2) Add the dopamine aqueous solution to the copper hydroxide colloidal particle stable suspension in step 1), incubate, and dopamine polymerizes on the surface of the copper hydroxide colloidal particles to form a cross-linked polydopamine coating layer.

[0012] 3) Add dilute hydrochloric acid to the solution obtained in step 2). The copper hydroxide colloid dissolves and releases copper ions, which are then adsorbed onto the surface of polydopamine.

[0013] 4) Add a reducing agent to the solution obtained in step 3). After the copper ions are reduced to copper nanoparticles, filter and dehydrate them, and wash them with distilled water to obtain copper nanoparticle-doped three-dimensional porous polydopamine.

[0014] 5) Copper nanoparticles doped with three-dimensional porous polydopamine and stearic acid are placed in a vacuum-sealed glass container and evacuated. The container is then heated until the stearic acid melts. The copper nanoparticles doped with three-dimensional porous polydopamine are then completely immersed in the liquid stearic acid by oscillation. The copper nanoparticles doped with three-dimensional porous polydopamine are then impregnated until the adsorption of the carrier copper nanoparticles is saturated. The copper nanoparticles doped with three-dimensional porous polydopamine in the saturated adsorption state are then removed and dried. When the stearic acid no longer precipitates, the shaped phase change thermal storage material of copper nanoparticles doped with three-dimensional porous polydopamine is obtained.

[0015] Preferably, the method for preparing the copper hydroxide colloidal particle stable suspension in step 1) includes adding copper chloride solution dropwise into boiling water, stopping heating when the suspension turns dark blue, and obtaining the copper hydroxide colloidal suspension after cooling.

[0016] As a further preferred embodiment, the concentration of the copper chloride solution in step 1) is 100g / L-320g / L, preferably 300g / L.

[0017] Preferably, the concentration of dopamine in step 2) is 10 g / L-30 g / L, and more preferably 20 g / L.

[0018] Preferably, in step 2), the volume ratio of dopamine to copper hydroxide colloidal particle stabilized suspension is 3:1-5:1, preferably 4:1.

[0019] Preferably, the concentration of dilute hydrochloric acid in step 3) is 0.3-0.6M, and more preferably 0.5M.

[0020] Preferably, the volume ratio of dilute hydrochloric acid in step 3) to the solution obtained in step 2) is 1:2-1:4, and more preferably 1:2.5.

[0021] Preferably, the reducing agent in step 4) is glucose.

[0022] Preferably, the weight-to-volume ratio (g / ml) of the reducing agent in step 4) to the solution obtained in step 3) is 1:2-1:5, and more preferably 1:3.5.

[0023] Preferably, the temperature at which the stearic acid is heated to melt in step 5) is 80°C-98°C, preferably 90°C.

[0024] Preferably, the drying temperature in step 5) is 80℃-98℃, preferably 90℃.

[0025] On another note, this invention provides an application of phase change thermal storage material based on biomimetic polymerization technology, which can be used for solar energy storage and utilization, industrial waste heat utilization, building energy conservation, etc.

[0026] The phase change thermal storage material based on biomimetic polymerization technology of this invention has the following advantages:

[0027] (1) The three-dimensional porous polydopamine prepared by biomimetic polymerization has a high loading capacity on the core material of phase change material, which can improve the energy storage density of shaped phase change thermal storage material prepared with three-dimensional porous polydopamine as carrier.

[0028] (2) The biomimetic polymerization preparation method has the advantages of simple operation, mild conditions and environmental friendliness;

[0029] (3) Copper nanoparticles are synthesized on the surface of three-dimensional porous polydopamine by in-situ reduction method. The copper nanoparticles synthesized by this method can be firmly and tightly bound to polydopamine, which can effectively reduce the surface thermal resistance between copper nanoparticles and polydopamine, improve thermal conductivity, and at the same time prevent the deposition of copper nanoparticles during the phase change process of the shaped phase change thermal storage material, improve its dispersion stability, and enhance the thermal conductivity of the shaped phase change thermal storage material.

[0030] (4) The phase change thermal energy storage material of the present invention has high energy storage density and good thermal conductivity, and can be used for solar energy storage and utilization, making a positive contribution to the realization of the country's important strategic goals of "carbon peaking" and "carbon neutrality". Detailed Implementation

[0031] The following examples are used to further explain and illustrate the present invention; however, they do not constitute a limitation or restriction on the scope of the present invention.

[0032] Example 1: Preparation of Copper Nanoparticles Doped with Three-Dimensional Porous Polydopamine

[0033] 1) Prepare a copper chloride solution by adding 15g CuCl2·2H2O to 50ml of distilled water;

[0034] 2) Add the copper chloride solution from step 1) dropwise into boiling water. Stop heating when the suspension turns dark blue. After cooling, you will get a copper hydroxide colloidal suspension.

[0035] 3) Add 200 ml of 20 g / L dopamine distilled aqueous solution to the copper hydroxide colloidal suspension in step 2) above, and incubate for 48 h. Dopamine polymerizes on the surface of copper hydroxide colloidal particles to form a cross-linked polydopamine coating layer.

[0036] 4) Add 100 ml of 0.5 M dilute hydrochloric acid to the suspension in step 3) above. The copper hydroxide colloid dissolves and releases copper ions, which are adsorbed on the surface of polydopamine.

[0037] 5) Add 10g of reducing agent (such as glucose, propyl formate, etc.) to the suspension in step 4) above, stir for 10min and incubate for 24h. After copper ions are reduced to copper nanoparticles, filter and dehydrate, wash with distilled water 5 times and vacuum dry at 45℃ for 24h to obtain 4.5g of copper nanoparticle-doped three-dimensional porous polydopamine (labeled as Poro-Cu-Dop).

[0038] Tests showed that Poro-Cu-Dop has a specific surface area of ​​up to 417.24 m². 2 / g, exhibits excellent adsorption and fixation capabilities for novel phase change materials;

[0039] Example 2: Preparation of Copper Nanoparticle-Doped Three-Dimensional Porous Polydopamine Shaped Phase Change Thermal Storage Material

[0040] 1) Place 50g of stearic acid and 0.5g of Poro-Cu-Dop in a custom-made vacuum-sealable glass container, evacuate using a vacuum pump and maintain for 30 minutes;

[0041] 2) Heat to 90℃ to melt stearic acid, and then immerse Poro-Cu-Dop completely in the liquid stearic acid by shaking;

[0042] 3) Vacuum impregnation for 2 hours to saturate the carrier with adsorption;

[0043] 4) Take out the Poro-Cu-Dop in the saturated adsorption state, transfer it to a drying oven, and dry it at 90℃ for 4 hours. When stearic acid no longer precipitates, 7.4g of copper nanoparticle-doped three-dimensional porous polydopamine shaped phase change thermal storage material (labeled as SA / Poro-Cu-Dop) is obtained.

[0044] Tests showed that the stearic acid loading in SA / Poro-Cu-Dop reached 93.28%, and the melting and solidification phase transition enthalpies of SA / Poro-Cu-Dop were 194.89 J / g and 208.51 J / g, respectively, with a thermal conductivity of 0.605 W / m·K.

[0045] For comparison, polydopamine particles were synthesized without a copper hydroxide colloidal particle template, and stearic acid was immobilized using these particles to prepare a polydopamine particle-based phase change thermal storage material. The comparison is as follows:

[0046] Comparative Example 1: Preparation of Polydopamine Particles

[0047] 1) Prepare a copper chloride solution by adding 15g CuCl2·2H2O to 50ml of distilled water;

[0048] 2) Add the copper chloride solution from step 1) dropwise into boiling water. Stop heating when the suspension turns dark blue. After cooling, you will get a copper hydroxide colloidal suspension.

[0049] 3) Filter the copper hydroxide colloidal suspension from step 2) to remove the copper hydroxide colloid and obtain a filtrate free of copper hydroxide colloid;

[0050] 4) Add 200 ml of a 20 g / L distilled aqueous solution of dopamine to the filtrate from step 3) above, and incubate with stirring for 48 h to polymerize dopamine into polydopamine particles.

[0051] 5) The mixture from step 3) was centrifuged to achieve solid-liquid separation. The polydopamine particles were washed three times with distilled water and then placed in a vacuum drying oven at 45°C for 24 hours to obtain 1.7g of polydopamine particles (labeled as: Poly-Dop). The specific surface area was measured to be 11.72m². 2 / g.

[0052] Comparative Example 2: Polydopamine Particle-Based Phase Change Thermal Storage Material

[0053] 1) Place 50g of stearic acid and 0.5g of Poly-Dop in a custom-made vacuum-sealable glass container, evacuate using a vacuum pump and maintain for 30 minutes;

[0054] 2) Heat to 90℃ to melt stearic acid, and then shake to completely immerse Poly-Dop in the liquid stearic acid;

[0055] 3) Vacuum impregnation for 2 hours to saturate the carrier with adsorption;

[0056] 4) Take out the Poly-Dop in the saturated adsorption state, transfer it to a drying oven, and dry it at 90℃ for 4 hours. When stearic acid no longer precipitates, 1.8g of polydopamine particle-shaped phase change thermal storage material (labeled as SA / Poly-Dop) is obtained.

[0057] Tests showed that the stearic acid loading in SA / Poly-Dop was 73.04%, and the melting and solidification phase transition enthalpies of SA / Poly-Dop were 132.66 J / g and 143.40 J / g, respectively, with a thermal conductivity of 0.291 W / m·K.

[0058] As can be seen from the above comparative examples, the copper nanoparticle-doped three-dimensional porous polydopamine shaped phase change thermal storage material prepared by the present invention significantly improves the loading capacity and phase change enthalpy of the shaped phase change thermal storage material due to the synthesis of three-dimensional porous polydopamine, and significantly improves the thermal conductivity of the shaped phase change thermal storage material due to the in-situ generation of copper nanoparticles on the surface of three-dimensional porous polydopamine.

[0059] For comparison, a three-dimensional porous polydopamine without copper nanoparticle doping was synthesized and used as a carrier to immobilize stearic acid to prepare a three-dimensional porous polydopamine-based shaped phase change thermal storage material. The comparison is as follows:

[0060] Comparative Example 3: Preparation of Three-Dimensional Porous Polydopamine

[0061] 1) Prepare a copper chloride solution by adding 15g CuCl2·2H2O to 50ml of distilled water;

[0062] 2) Add copper chloride solution dropwise into boiling water. Stop heating when the suspension turns dark blue. After cooling, you will get a copper hydroxide colloidal suspension.

[0063] 3) Add 200 ml of 20 g / L dopamine distilled aqueous solution to the above copper hydroxide colloidal suspension and incubate for 48 h. Dopamine polymerizes on the surface of copper hydroxide colloidal particles to form a cross-linked polydopamine coating layer.

[0064] 4) Add 100 ml of 0.5 M dilute hydrochloric acid to the above suspension. The copper hydroxide colloid dissolves. Solid-liquid separation is achieved by filtration. The solid phase is washed five times with distilled water and then vacuum dried at 45 °C for 24 h to obtain 1.6 g of three-dimensional porous polydopamine (labeled Poro-Dop1). The specific surface area of ​​Poro-Dop1 is tested to be 439.50 m². 2 / g.

[0065] Comparative Example 4: Three-dimensional porous polydopamine-based shaped phase change thermal storage material

[0066] 1) Place 50g of stearic acid and 0.5g of Poro-Dop1 in a custom-made vacuum-sealed glass container, evacuate using a vacuum pump and maintain for 30 minutes;

[0067] 2) Heat to 90°C to melt stearic acid, and then shake to completely immerse Poro-Dop1 in the liquid stearic acid;

[0068] 3) Vacuum impregnation for 2 hours to saturate the carrier with adsorption;

[0069] 4) Take out the Poro-Dop1 in the saturated adsorption state, transfer it to a drying oven, and dry it at 90℃ for 4 hours. When stearic acid no longer precipitates, 7.9g of three-dimensional porous polydopamine shaped phase change thermal storage material (labeled as SA / Poro-Dop1) is obtained.

[0070] Tests showed that the stearic acid loading in SA / Poro-Dop1 can reach 93.74%, and the melting and solidification phase transition enthalpies of SA / Poro-Dop1 are 195.02 J / g and 208.73 J / g, respectively, with a thermal conductivity of 0.260 W / m·K.

[0071] The comparative examples above show that when no copper nanoparticles are generated, the loading and phase change enthalpy of SA / Poro-Dop1 are not significantly different from those of SA / Poro-Cu-Dop, but the thermal conductivity of SA / Poro-Dop1 is significantly reduced. When copper nanoparticles are generated, the thermal conductivity of SA / Poro-Cu-Dop is increased by 132.7% compared to that of SA / Poro-Dop1. Therefore, in this invention, the in-situ generation of copper nanoparticles on the surface of three-dimensional porous polydopamine plays an important role in improving the thermal conductivity of shaped phase change thermal storage materials.

[0072] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a phase change thermal storage material based on biomimetic polymerization technology, characterized in that, The phase change thermal storage material is a shaped phase change thermal storage material doped with copper nanoparticles and three-dimensional porous polydopamine. By weight percentage, the phase change thermal storage material based on biomimetic polymerization technology comprises the following components: Carrier 5%-40% Shaped phase change thermal storage material core material 60%-95% The carrier is copper nanoparticles doped with three-dimensional porous polydopamine; the core material of the shaped phase change thermal storage material is stearic acid. The preparation method includes: 1) Preparation of a stable suspension of copper hydroxide colloidal particles; 2) Add the dopamine aqueous solution to the copper hydroxide colloidal particle stable suspension in step 1), incubate, and dopamine polymerizes on the surface of the copper hydroxide colloidal particles to form a cross-linked polydopamine coating layer. 3) Add dilute hydrochloric acid to the solution obtained in step 2). The copper hydroxide colloid dissolves and releases copper ions, which are then adsorbed onto the surface of polydopamine. 4) Add a reducing agent to the solution obtained in step 3). After the copper ions are reduced to copper nanoparticles, filter and dehydrate them, and wash them with distilled water to obtain copper nanoparticle-doped three-dimensional porous polydopamine. 5) Copper nanoparticles doped with three-dimensional porous polydopamine and stearic acid are placed in a vacuum-sealed glass container and heated until the stearic acid melts. The copper nanoparticles doped with three-dimensional porous polydopamine are then completely immersed in the liquid stearic acid by oscillation. The copper nanoparticles doped with three-dimensional porous polydopamine are impregnated until the adsorption of the carrier copper nanoparticles is saturated. The copper nanoparticles doped with three-dimensional porous polydopamine in the saturated adsorption state are taken out and dried. When the stearic acid no longer precipitates, the shaped phase change thermal storage material of copper nanoparticles doped with three-dimensional porous polydopamine is obtained.

2. The method for preparing a phase change thermal storage material based on biomimetic polymerization technology according to claim 1, characterized in that... The method for preparing the copper hydroxide colloidal particle stable suspension in step 1) includes adding copper chloride solution dropwise into boiling water, stopping heating when the suspension turns dark blue, and obtaining the copper hydroxide colloidal suspension after cooling.

3. The method for preparing a phase change thermal storage material based on biomimetic polymerization technology according to claim 2, characterized in that, The concentration of the copper chloride solution in step 1) is 100g / L-320g / L.

4. The method for preparing a phase change thermal storage material based on biomimetic polymerization technology according to claim 1, characterized in that... The concentration of dopamine in step 2) is 10 g / L-30 g / L; the volume ratio of dopamine to copper hydroxide colloidal particle stable suspension in step 2) is 3:1-5:

1.

5. The method for preparing a phase change thermal storage material based on biomimetic polymerization technology according to claim 1, characterized in that... The concentration of dilute hydrochloric acid in step 3) is 0.3-0.6M; the volume ratio of dilute hydrochloric acid in step 3) to the solution obtained in step 2) is 1:2-1:

4.

6. The method for preparing a phase change thermal storage material based on biomimetic polymerization technology according to claim 1, characterized in that, The reducing agent in step 4) is glucose; the weight-to-volume ratio of the reducing agent in step 4) to the solution obtained in step 3) is 1:2-1:5 (g / ml).

7. The method for preparing a phase change thermal storage material based on biomimetic polymerization technology according to claim 1, characterized in that... In step 5), the temperature at which the stearic acid is heated to melt is 80°C-98°C.

8. The method for preparing a phase change thermal storage material based on biomimetic polymerization technology according to claim 1, characterized in that... The drying temperature in step 5) is 80℃-98℃.

9. The application of the phase change thermal storage material synthesized by the preparation method of the phase change thermal storage material based on biomimetic polymerization technology as described in claim 1, wherein the application is in the fields of solar energy storage and utilization, industrial waste heat utilization, or building energy conservation.