Preparation method of phase change coupling thermochromism regulated radiation cooling wood

Abstract

The invention discloses a preparation method of phase change coupling thermochromism regulated radiation cooling wood, which comprises the following steps: S1, mixing trifluoropropyl trimethyl cyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyldihydrodisiloxane, adding an n-heptane diluted solution, and reacting to prepare hydrogen-terminated polysiloxane; the preparation method comprises the following steps: adding acrylic acid into a polyethylene glycol solution, and reacting to prepare polyethylene glycol acrylate; adding polysiloxane into the polyethylene glycol acrylate solution, and reacting to obtain the radiation cooling coupled solid-solid phase change material; the radiation cooling coupling solid-solid phase change material and the reversible thermochromic micro-glue are prepared, the radiation cooling coupling solid-solid phase change material and the reversible thermochromic micro-glue are further combined with wood to obtain the phase change coupling thermochromic regulated radiation cooling wood, and the radiation cooling wood has the characteristics of high radiation cooling capacity and stable form.

Description

Technical Field

[0001] The invention relates to the field of functional materials, and in particular to a method for preparing radiation cooling wood regulated by phase change coupled thermochromism. Background Art

[0002] Global warming and the greenhouse effect have brought severe challenges to cooling methods, especially in the field of construction. The energy consumption of thermal management in the operation stage of buildings has accounted for half of the entire stage. Therefore, it is urgent to find a new and energy-saving cooling method. Passive radiation cooling is a cooling method in which materials spontaneously emit electromagnetic waves through the window of the atmosphere to the cold universe to exchange heat according to their own chemical composition. It can cool down all day long and does not require additional energy input. Therefore, it is a zero-carbon thermal management method.

[0003] Designing and preparing radiation cooling materials to achieve building cooling is highly feasible and has broad application prospects, but there are also many temperature issues to be resolved. At present, the net cooling power of radiation cooling materials urgently needs to be broken through, and its continuous passive cooling process is not applicable in most areas with large temperature differences between day and night. The main problems are as follows:

[0004] 1. Thermochromic materials are used as switches to control the start and stop of radiative cooling at different temperatures. However, the additional doping of thermochromic materials affects the cooling performance of radiative cooling and does not achieve better cooling effects when cooling is required.

[0005] 2. Doping with nanoparticles with high emissivity can enhance the radiation cooling capability while improving both reflectivity and emissivity, but in theory it is still impossible to break through the limitation of net cooling power.

[0006] 3. Phase change materials coupled with radiation cooling materials can break through the cooling performance limitations of radiation cooling materials through the thermal enthalpy of phase change materials, and before and after the phase change temperature, the phase change material can dynamically adjust the radiation cooling effect with temperature, but the self-generated phase instability of the phase change material is a huge problem. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing phase-change coupled thermochromic regulated radiation cooling wood. The present invention prepares radiation cooling coupled solid-solid phase change material and reversible thermochromic microgel, and further combines the former with wood to obtain phase-change coupled thermochromic regulated radiation cooling wood, which has the characteristics of high radiation cooling capacity and stable morphology.

[0008] The technical solution provided by the present invention is as follows: A method for preparing radiation cooling wood regulated by phase change coupled thermochromism, which is carried out according to the following steps:

[0009] Step S1: trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyldihydrodisiloxane are mixed and added into a diluted n-heptane solution to react and prepare hydrogen-terminated polysiloxane; acrylic acid is added into a polyethylene glycol solution to react and prepare polyethylene glycol acrylate; polysiloxane is added into the polyethylene glycol acrylate solution to react and obtain a radiation cooling coupled solid-solid phase change material;

[0010] Step S2: dodecanol, crystal violet lactone and bisphenol A are mixed, and then pentaerythritol triacrylate is added; styrene maleic anhydride copolymer is hydrolyzed and then added to the mixture, and a uniform emulsion is obtained after emulsification; methyl methacrylate and an initiator are mixed and then added to the emulsion, and reversible thermochromic microcapsules are obtained after reaction;

[0011] Step S3: After mixing the radiation cooling coupled solid-solid phase change material and the reversible thermochromic microcapsules, the delignified wood is subjected to vacuum pressure impregnation treatment by a full cell method, and the treated wood is vacuum dried to obtain radiation cooling wood regulated by phase change coupled thermochromism.

[0012] In the above-mentioned preparation method of radiation cooling wood regulated by phase change coupled thermochromism, the molar ratio of trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyldihydrodisiloxane in step S1 is 1:0.9-1.1:0.035-0.045, and the mixed reaction conditions are nitrogen protection and heating and stirring in a water bath at 70-80°C until the mixed system is uniform and stable; trifluoromethanesulfonic acid accounting for 3%-7% of the total mass of the system is added to the stable mixed system and heated for 5-7h until the reaction is completed, and the reaction conditions of the mixed system and the n-heptane dilution solution are pH=6.5-7.5, and after the reaction, the hydrogen-terminated polysiloxane is obtained by filtration, washing and distillation.

[0013] In the aforementioned method for preparing radiation cooling wood regulated by phase change coupled thermochromism, the polyethylene glycol solution is a solution of polyethylene glycol with a molecular weight of 1000-4000 and 0.35-0.45wt% of hydroquinone uniformly mixed at 55-65°C; 0.5-1.5% of p-toluenesulfonic acid is added to the acrylic acid; the molar ratio of acrylic acid to polyethylene glycol is 1.5-2.5:1, and the reaction conditions are a temperature of 130-150°C, a stirring rate of 350-450rpm, and a duration of 7-9h.

[0014] In the aforementioned method for preparing radiation cooling wood regulated by phase change coupled thermochromism, the polysiloxane is added with polyethylene glycol acrylate solution, and then Karstedt catalyst is added and reacted at 70-90° C. for 9-11 hours to obtain radiation cooling coupled solid-solid phase change material.

[0015] In the aforementioned method for preparing the radiation cooling wood regulated by phase change coupled thermochromism, the molar ratio of dodecanol, crystal violet lactone and bisphenol A is 95-105:1:9-11.

[0016] In the aforementioned method for preparing radiation-cooled wood regulated by phase change coupled thermochromism, the emulsification conditions are a temperature of 55-65° C., a stirring rate of 3800-4200 rpm, and a duration of 12-18 min.

[0017] In the aforementioned preparation method of phase change coupled thermochromic regulated radiation cooling wood, the mass ratio of the emulsion to methyl methacrylate core wall material is 0.9-1.1:1; the initiator is azobisisobutyronitrile with a mass fraction of 0.18-0.22wt%; the reaction conditions of methyl methacrylate and azobisisobutyronitrile being mixed and added to the emulsion are a temperature of 75-85°C and a time of 3-5h. After the reaction, the emulsion is filtered, washed and vacuum dried to obtain reversible thermochromic microcapsules.

[0018] In the aforementioned method for preparing the radiation cooling wood regulated by phase change coupled thermochromism, the wood is high-permeability Populus cathayana.

[0019] In the aforementioned method for preparing radiation cooling wood regulated by phase change coupled thermochromism, the vacuum pressurization conditions are a pressure of 0-2 MPa and a duration of 30-90 min.

[0020] In the aforementioned method for preparing radiation-cooled wood regulated by phase change coupled thermochromism, the vacuum drying conditions are a temperature of 45-55° C. and a duration of 10-14 hours.

[0021] Compared with the prior art, the present invention prepares radiation cooling coupled solid-solid phase change materials and reversible thermochromic microcapsules, and further fills the two into wood through a full cell method to obtain radiation cooling wood regulated by phase change coupled thermochromism; microphase separation and reversible thermochromic microcapsules in the synthesis process of radiation cooling coupled solid-solid phase change materials enable the material to have a certain reflectivity in the solar spectrum, thereby ensuring that the material has radiation cooling ability, and at the same time, the wall materials of the radiation cooling coupled solid-solid phase change material and the reversible thermochromic microcapsules have higher thermal enthalpy values ​​and are morphologically stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the preparation process of the present invention;

[0023] Figure 2 Schematic diagram of the synthesis of reversible thermochromic microcapsules of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the embodiments and drawings, but they are not intended to limit the present invention.

[0025] Example 1: A method for preparing a phase-change coupled thermochromic radiation cooling wood, as shown in the attached Figure 1 As shown, follow the steps below:

[0026] Step S1: trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyldihydrodisiloxane are added to a three-necked flask at a molar ratio of 1:0.9:0.035, and mixed, and nitrogen is introduced for protection, and the mixed system is heated and stirred in a water bath at 70°C to make the mixed system uniform and stable, and 3% trifluoromethanesulfonic acid is added and heated for 5 hours until the reaction is completed; then n-heptane is added to dilute the solution and the pH is adjusted to 6.5, and hydrogen-terminated polysiloxane is obtained after filtering, washing and distilling; polyethylene glycol with a molecular weight of 1000 and 0.35wt% of p-toluene are added to obtain a hydrogen-terminated polysiloxane; The diphenols were mixed uniformly at 55° C. to obtain a polyethylene glycol solution, 0.5% of p-toluenesulfonic acid by mass was added to acrylic acid at a molar ratio of 1.5:1 to the polyethylene glycol, the mixture was added to the polyethylene glycol solution, the temperature was raised to 130° C., the stirring rate was 350 rpm, and the polyethylene glycol acrylate was obtained after 7 hours of reaction; polysiloxane was added to the polyethylene glycol acrylate solution, 0.3% of the total mass of the reaction system was added with a Karstedt catalyst, and the reaction was carried out at 70° C. for 9 hours to obtain a radiation cooling coupled solid-solid phase change material;

[0027] Step S2: As shown in the attached Figure 2 As shown, dodecanol, crystal violet lactone and bisphenol A are mixed in a molar ratio of 95:1:9, and then pentaerythritol triacrylate (cross-linking agent) accounting for 10% of the total mass of the core wall material is added, and styrene maleic anhydride copolymer (emulsifier) ​​accounting for 3% of the total mass of the emulsion is hydrolyzed and added to the mixture, and emulsified at 55°C and a stirring rate of 3800rpm for 12min to obtain a uniform emulsion; methyl methacrylate and 0.18wt% azobisisobutyronitrile are mixed and added to the emulsion, and the core wall material mass ratio of the emulsion to methyl methacrylate is 0.9:1, and the temperature is raised to 75°C for reaction for 3h, and the emulsion is filtered, washed, and vacuum dried to obtain reversible thermochromic microcapsules;

[0028] Step S3: Place Populus cathayana in NaOH and Na 2 SO 3 The mixed solution was heated to boiling and treated for 12 h to remove lignin, then washed with ionized water and placed in 0.1 mol / L NaClO 2 The wood was completely bleached in the solution; the radiation cooling coupled solid-solid phase change material and the reversible thermochromic microcapsules were mixed and the bleached wood was subjected to vacuum pressure impregnation treatment by the full cell method. The vacuum pressure conditions were 0 MPa pressure and 30 min. The treated wood was vacuum dried at 45 °C for 10 h to obtain radiation cooling wood regulated by phase change coupled thermochromism.

[0029] Example 2: A method for preparing a phase change coupled thermochromic regulated radiation cooling wood, according to the following steps:

[0030] Step S1: trifluoropropyl trimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyldihydrodisiloxane are added to a three-necked flask at a molar ratio of 1:1:0.035, and mixed, and nitrogen is introduced for protection, and the mixed system is heated and stirred in a water bath at 70°C to make the mixed system uniform and stable, and 4% trifluoromethanesulfonic acid is added and heated for 5.5 hours until the reaction is completed; then n-heptane is added to dilute the solution and the pH is adjusted to 7, and hydrogen-terminated polysiloxane is obtained after filtering, washing and distilling; polyethylene glycol with a molecular weight of 2000 and 0.4wt% of p-toluene are added to obtain a hydrogen-terminated polysiloxane; The diphenols are mixed uniformly at 60° C. to obtain a polyethylene glycol solution, 1% of p-toluenesulfonic acid by mass is added to acrylic acid at a molar ratio of 2:1 to the polyethylene glycol, the mixture is added to the polyethylene glycol solution, the temperature is raised to 140° C., the stirring rate is 400 rpm, and the polyethylene glycol acrylate is obtained after 8 hours of reaction; polysiloxane is added to the polyethylene glycol acrylate solution, 0.3% of the total mass of the reaction system is added with a Karstedt catalyst, and the reaction is carried out at 80° C. for 10 hours to obtain a radiation cooling coupled solid-solid phase change material;

[0031] Step S2: dodecanol, crystal violet lactone and bisphenol A are mixed in a molar ratio of 100:1:9, and then pentaerythritol triacrylate accounting for 10% of the total mass of the core wall material is added, styrene maleic anhydride copolymer accounting for 3% of the total mass of the emulsion is hydrolyzed and added to the mixture, and emulsified at 60° C. and a stirring rate of 4000 rpm for 14 minutes to obtain a uniform emulsion; methyl methacrylate and 0.2wt% azobisisobutyronitrile are mixed and added to the emulsion, and the mass ratio of the emulsion to the core wall material of methyl methacrylate is 1:1, the temperature is raised to 80° C. for reaction for 3 hours, and the emulsion is filtered, washed, and vacuum dried to obtain reversible thermochromic microcapsules;

[0032] Step S3: Place Populus cathayana in NaOH and Na 2 SO 3 The mixed solution was heated to boiling and treated for 12 h to remove lignin, then washed with ionized water and placed in 0.1 mol / L NaClO 2 The wood was completely bleached in the solution; the radiation cooling coupled solid-solid phase change material and the reversible thermochromic microcapsules were mixed and the bleached wood was subjected to vacuum pressure impregnation treatment by the full cell method. The vacuum pressure conditions were a pressure of 0.5 MPa and a duration of 40 min. The treated wood was vacuum dried at 50°C for 10 h to obtain radiation cooling wood regulated by phase change coupled thermochromism.

[0033] Example 3: A method for preparing a phase change coupled thermochromic regulated radiation cooling wood, according to the following steps:

[0034] Step S1: trifluoropropyl trimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyldihydrodisiloxane are added to a three-necked flask at a molar ratio of 1:1.1:0.04, and mixed. Nitrogen is introduced for protection. The mixed system is heated and stirred in a water bath at 80°C to make the mixed system uniform and stable. 5% trifluoromethanesulfonic acid is added and heated for 6 hours until the reaction is completed; then n-heptane is added to dilute the solution and the pH is adjusted to 7.5, and hydrogen-terminated polysiloxane is obtained after filtering, washing and distilling; polyethylene glycol with a molecular weight of 3000 and 0.45wt% of terephthalate are added to obtain a hydrogen-terminated polysiloxane; Phenol is mixed uniformly at 65° C. to obtain a polyethylene glycol solution, 1.5% of p-toluenesulfonic acid by mass is added to acrylic acid at a molar ratio of 2.5:1 to the polyethylene glycol, the mixture is added to the polyethylene glycol solution, the temperature is raised to 150° C., the stirring rate is 450 rpm, and the polyethylene glycol acrylate is obtained after 9 hours of reaction; polysiloxane is added to the polyethylene glycol acrylate solution, 0.3% of the total mass of the reaction system is added with a Karstedt catalyst, and the reaction is carried out at 90° C. for 11 hours to obtain a radiation cooling coupled solid-solid phase change material;

[0035] Step S2: dodecanol, crystal violet lactone and bisphenol A are mixed in a molar ratio of 105:1:11, and then pentaerythritol triacrylate accounting for 10% of the total mass of the core wall material is added; styrene maleic anhydride copolymer accounting for 3% of the total mass of the emulsion is hydrolyzed and added to the mixture, and emulsified at 65° C. and a stirring rate of 4200 rpm for 18 minutes to obtain a uniform emulsion; methyl methacrylate and 0.22wt% azobisisobutyronitrile are mixed and added to the emulsion, and the mass ratio of the emulsion to methyl methacrylate as the core wall material is 1.1:1, and the temperature is raised to 85° C. for reaction for 5 hours, and the emulsion is filtered, washed, and vacuum dried to obtain reversible thermochromic microcapsules;

[0036] Step S3: Place Populus cathayana in NaOH and Na 2 SO 3 The mixed solution was heated to boiling and treated for 12 h to remove lignin, then washed with ionized water and placed in 0.1 mol / L NaClO 2 The wood was completely bleached in the solution; the radiation cooling coupled solid-solid phase change material and the reversible thermochromic microcapsules were mixed and the bleached wood was subjected to vacuum pressure impregnation treatment by the full cell method. The vacuum pressure conditions were a pressure of 1 MPa and a duration of 50 min. The treated wood was vacuum dried at 55°C for 14 h to obtain radiation cooling wood regulated by phase change coupled thermochromism.

[0037] Example 4: A method for preparing a phase change coupled thermochromic regulated radiation cooling wood, according to the following steps:

[0038] Step S1: trifluoropropyl trimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyldihydrodisiloxane are added to a three-necked flask at a molar ratio of 1:1.1:0.045, and mixed, and nitrogen is introduced for protection, and the mixed system is heated and stirred in a water bath at 70°C to make the mixed system uniform and stable, and 7% trifluoromethanesulfonic acid is added and heated for 7 hours until the reaction is completed; then n-heptane is added to dilute the solution and the pH is adjusted to 7, and hydrogen-terminated polysiloxane is obtained after filtering, washing and distilling; polyethylene glycol with a molecular weight of 4000 and 0.4wt% of p-toluene are added to obtain a hydrogen-terminated polysiloxane; The diphenols are mixed uniformly at 65° C. to obtain a polyethylene glycol solution, 1% of p-toluenesulfonic acid by mass is added to acrylic acid at a molar ratio of 2:1 to the polyethylene glycol, the mixture is added to the polyethylene glycol solution, the temperature is raised to 145° C., the stirring rate is 400 rpm, and the polyethylene glycol acrylate is obtained after 8 hours of reaction; polysiloxane is added to the polyethylene glycol acrylate solution, 0.3% of the total mass of the reaction system is added with a Karstedt catalyst, and the reaction is carried out at 85° C. for 10 hours to obtain a radiation cooling coupled solid-solid phase change material;

[0039] Step S2: dodecanol, crystal violet lactone and bisphenol A are mixed in a molar ratio of 100:1:11, and then 10% of the total mass of the core wall material pentaerythritol triacrylate is added, 3% of the total mass of the emulsion is hydrolyzed and added to the mixture, and emulsified at 60° C. and a stirring rate of 4200 rpm for 16 minutes to obtain a uniform emulsion; methyl methacrylate and 0.2wt% azobisisobutyronitrile are mixed and added to the emulsion, and the mass ratio of the emulsion to the core wall material of methyl methacrylate is 1:1, the temperature is raised to 80° C. for reaction for 5 hours, and the emulsion is filtered, washed, and vacuum dried to obtain reversible thermochromic microcapsules;

[0040] Step S3: Place Populus cathayana in NaOH and Na 2 SO 3 The mixed solution was heated to boiling and treated for 12 h to remove lignin, then washed with ionized water and placed in 0.1 mol / L NaClO 2 The wood was completely bleached in the solution; the radiation cooling coupled solid-solid phase change material and the reversible thermochromic microcapsules were mixed and the bleached wood was subjected to vacuum pressure impregnation treatment by the full cell method. The vacuum pressure conditions were a pressure of 2 MPa and a duration of 70 min. The treated wood was vacuum dried at 50°C for 13 h to obtain radiation cooling wood regulated by phase change coupled thermochromism.

[0041] Example 5: A method for preparing a phase change coupled thermochromic regulated radiation cooling wood, according to the following steps:

[0042] Step S1: trifluoropropyl trimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyldihydrodisiloxane are added to a three-necked flask at a molar ratio of 1:1:0.04, and nitrogen is introduced for protection. The mixed system is heated and stirred in a water bath at 75°C to make the mixed system uniform and stable. 5% trifluoromethanesulfonic acid is added and heated for 6 hours until the reaction is completed; then n-heptane is added to dilute the solution and the pH is adjusted to 7, and hydrogen-terminated polysiloxane is obtained after filtering, washing and distilling; polyethylene glycol with a molecular weight of 4000 and 0.45wt% of hydroquinone are added. The mixture was mixed evenly at 65° C. to obtain a polyethylene glycol solution, 1.5% of p-toluenesulfonic acid by mass was added to acrylic acid at a molar ratio of 2:1 to the polyethylene glycol, the mixture was added to the polyethylene glycol solution after mixing, the mixture was heated to 140° C., the stirring rate was 450 rpm, and the reaction was performed for 8 hours to obtain polyethylene glycol acrylate; polysiloxane was added to the polyethylene glycol acrylate solution, 0.3% of the total mass of the reaction system was added with a Karstedt catalyst, and the mixture was reacted at 85° C. for 10 hours to obtain a radiation cooling coupled solid-solid phase change material;

[0043] Step S2: dodecanol, crystal violet lactone and bisphenol A are mixed in a molar ratio of 100:1:10, and then pentaerythritol triacrylate accounting for 10% of the total mass of the core wall material is added; styrene maleic anhydride copolymer accounting for 3% of the total mass of the emulsion is hydrolyzed and added to the mixture, and emulsified at 65° C. and a stirring rate of 4200 rpm for 15 minutes to obtain a uniform emulsion; methyl methacrylate and 0.22wt% azobisisobutyronitrile are mixed and added to the emulsion, and the mass ratio of the emulsion to the core wall material of methyl methacrylate is 1:1, and the temperature is raised to 80° C. for reaction for 4 hours, and the emulsion is filtered, washed, and vacuum dried to obtain reversible thermochromic microcapsules;

[0044] Step S3: Place Populus cathayana in NaOH and Na 2 SO 3 The mixed solution was heated to boiling and treated for 12 h to remove lignin, then washed with ionized water and placed in 0.1 mol / L NaClO 2 The wood was completely bleached in the solution; the radiation cooling coupled solid-solid phase change material and the reversible thermochromic microcapsules were mixed and the bleached wood was subjected to vacuum pressure impregnation treatment by the full cell method. The vacuum pressure conditions were a pressure of 1 MPa and a duration of 90 min. The treated wood was vacuum dried at 50°C for 14 h to obtain radiation cooling wood regulated by phase change coupled thermochromism.

[0045] Example 6: A method for preparing a phase-change coupled thermochromic regulated radiation cooling wood, according to the following steps:

[0046] Step S1: trifluoropropyl trimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyldihydrodisiloxane are added to a three-necked flask at a molar ratio of 1:1:0.04, and nitrogen is introduced for protection. The mixed system is heated and stirred in a water bath at 75°C to make the mixed system uniform and stable. 5% trifluoromethanesulfonic acid is added and heated for 6 hours until the reaction is completed; then n-heptane is added to dilute the solution and the pH is adjusted to 7, and hydrogen-terminated polysiloxane is obtained after filtering, washing and distilling; polyethylene glycol with a molecular weight of 2000 and 0.4wt% hydroquinone are added. Mixing evenly at 60° C. to obtain a polyethylene glycol solution, adding 1% of p-toluenesulfonic acid by mass to acrylic acid at a molar ratio of 2:1 to polyethylene glycol, adding the mixture to the polyethylene glycol solution after mixing, heating to 140° C., stirring at a rate of 400 rpm, and reacting for 8 hours to obtain polyethylene glycol acrylate; adding polysiloxane to the polyethylene glycol acrylate solution, adding 0.3% of the total mass of the reaction system Karstedt catalyst, and reacting at 80° C. for 10 hours to obtain a radiation cooling coupled solid-solid phase change material;

[0047] Step S2: dodecanol, crystal violet lactone and bisphenol A are mixed in a molar ratio of 100:1:10, and then pentaerythritol triacrylate accounting for 10% of the total mass of the core wall material is added; styrene maleic anhydride copolymer accounting for 3% of the total mass of the emulsion is hydrolyzed and added to the mixture, and emulsified at 60° C. and a stirring rate of 4000 rpm for 15 minutes to obtain a uniform emulsion; methyl methacrylate and 0.2wt% azobisisobutyronitrile are mixed and added to the emulsion, and the mass ratio of the emulsion to the core wall material of methyl methacrylate is 1:1, and the temperature is raised to 80° C. for reaction for 4 hours, and the emulsion is filtered, washed, and vacuum dried to obtain reversible thermochromic microcapsules;

[0048] Step S3: Place Populus cathayana in NaOH and Na 2 SO 3 The mixed solution was heated to boiling and treated for 12 h to remove lignin, then washed with ionized water and placed in 0.1 mol / L NaClO 2 The wood was completely bleached in the solution; the radiation cooling coupled solid-solid phase change material and the reversible thermochromic microcapsules were mixed and the bleached wood was subjected to vacuum pressure impregnation treatment by the full cell method. The vacuum pressure conditions were a pressure of 1 MPa and a duration of 60 min. The treated wood was vacuum dried at 50°C for 12 h to obtain radiation cooling wood regulated by phase change coupled thermochromism.

[0049] The radiative cooling wood prepared in Example 6 with phase change coupling thermochromic regulation has better reflectivity and morphological stability than the other examples. When it is applied in practice, by constructing a ternary coupling system of "radiative cooling - phase change energy storage - thermochromism", the wood is endowed with dynamic thermal management capabilities; the radiative cooling coupled with solid-solid phase change materials relies on the microphase separation structure of polysiloxane and polyethylene glycol acrylate to form a high emissivity channel (>90%) in the 8-13μm atmospheric window. At the same time, the latent heat storage is realized by the crystallization-amorphous phase transition of the polyethylene glycol segment (the phase change enthalpy reaches 80-120J / g); the reversible thermochromic microcapsules use methyl methacrylate as the wall material to encapsulate the dodecanol-crystal violet lactone-bisphenol A system. Through the temperature-triggered molecular conformation change (the color change threshold is 28±2°C), it presents white (solar reflectivity >85%) at high temperature (>30°C) to enhance light reflection, and turns blue (reflectivity <30%) at low temperature (<25°C) to reduce radiative heat dissipation, forming a synergistic regulation mechanism of "light reflection - thermal radiation - phase change heat"; this wood has the following characteristics: 1. High-efficiency radiative cooling, through the microphase separation structure and high emissivity coating, the daytime net cooling power reaches 90-110W / m2 (20% higher than traditional radiative cooling materials), and the nighttime radiative cooling amplitude reaches 8-12°C; 2. Intelligent temperature-sensitive regulation, using the stable phase state of the solid-solid phase change material (no risk of liquid leakage) and the reversible response of the thermochromic microcapsules to dynamically balance in the temperature difference fluctuation scenario: at high temperature, the phase change material absorbs the excess heat in the 20-30°C range and reflects solar radiation through the white microcapsules, and at low temperature, it releases the stored heat and inhibits the long-wave radiation loss through the blue microcapsules, reducing the surface temperature fluctuation range of the wood by 40%-60%; 3. Long-term stable and durable, the hydrophobic network of polysiloxane forms a covalent bond with the hydroxyl group of wood cellulose (bonding strength >5MPa), combined with the full-cell method of vacuum pressure impregnation (the impregnation depth reaches the wood core layer), the functional material loading rate reaches 35%-40%, and the performance decay is <5% after 500 thermal cycles, solving the problems of unstable phase state and interface shedding of traditional phase change materials.

[0050] In summary, the phase-change coupled thermochromic regulated radiation cooling wood has extremely high emissivity in the 8-13 micron atmospheric window band. The microphase separation and reversible thermochromic microcapsules in the synthesis process of radiation cooling coupled solid-solid phase change materials make the material have a certain reflectivity in the solar spectrum, thereby ensuring the excellent radiation cooling ability of the material. In addition, the wall materials of the radiation cooling coupled solid-solid phase change materials and reversible thermochromic microcapsules have high thermal enthalpy values ​​and are morphologically stable. In practical applications, the radiation cooling wood coupled with thermochromic regulated radiation cooling can dynamically regulate the radiation cooling ability, which is specifically manifested as radiation cooling at high temperatures. However, the coupled solid-solid phase change material absorbs heat to promote cooling, and the reversible thermochromic microcapsules are white to enhance reflection; at low temperatures, radiative cooling is coupled with solid-solid phase change material to release heat to curb cooling, and the reversible thermochromic microcapsules are blue to curb reflection. At the same time, no phase transition occurs during the heat absorption and release process, which improves the durability of the radiative cooling coupled solid-solid phase change material; this material breaks through the application limitations of passive radiative cooling in day and night temperature difference scenarios through the synergy of multiple mechanisms of "spectral selective regulation-phase change latent heat buffering-structural stabilization", and provides a green building material solution for building envelope structures that combines efficient cooling, intelligent temperature regulation and long life, and has significant application value and industrialization prospects in low-carbon buildings, cold chain warehousing and other fields.

Claims

1. A method for preparing radiative cooling wood regulated by phase change coupled thermochromism, characterized in that: Follow these steps: Step S1: trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyldihydrodisiloxane are mixed and added into a diluted n-heptane solution to react and prepare hydrogen-terminated polysiloxane; acrylic acid is added into a polyethylene glycol solution to react and prepare polyethylene glycol acrylate; polysiloxane is added into the polyethylene glycol acrylate solution to react and obtain a radiation cooling coupled solid-solid phase change material; Step S2: dodecanol, crystal violet lactone and bisphenol A are mixed, and then pentaerythritol triacrylate is added; styrene maleic anhydride copolymer is hydrolyzed and then added to the mixture, and a uniform emulsion is obtained after emulsification; methyl methacrylate and an initiator are mixed and then added to the emulsion, and reversible thermochromic microcapsules are obtained after reaction; Step S3: After mixing the radiation cooling coupled solid-solid phase change material and the reversible thermochromic microcapsules, the delignified wood is subjected to vacuum pressure impregnation treatment by a full cell method, and the treated wood is vacuum dried to obtain radiation cooling wood regulated by phase change coupled thermochromism.

2. The method for preparing the phase change coupled thermochromic regulated radiation cooling wood according to claim 1, characterized in that: In the step S1, the molar ratio of trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyldihydrodisiloxane is 1:0.9-1.1:0.035-0.045, and the mixed reaction conditions are nitrogen protection and heating and stirring in a water bath at 70-80°C until the mixed system is uniform and stable; 3%-7% of trifluoromethanesulfonic acid accounting for the total mass of the system is added to the stable mixed system, and heated for 5-7h until the reaction is completed. The reaction conditions of the mixed system and the n-heptane dilution solution are pH=6.5-7.5, and after the reaction, the hydrogen-terminated polysiloxane is obtained by filtering, washing and distilling.

3. The method for preparing the phase change coupled thermochromic regulated radiation cooling wood according to claim 1, characterized in that: The polyethylene glycol solution is a solution in which polyethylene glycol with a molecular weight of 1000-4000 and 0.35-0.45wt% of hydroquinone are uniformly mixed at 55-65°C; 0.5-1.5% of p-toluenesulfonic acid is added to the acrylic acid; the molar ratio of the acrylic acid to the polyethylene glycol is 1.5-2.5:1, and the reaction conditions are a temperature of 130-150°C, a stirring rate of 350-450rpm, and a reaction time of 7-9h.

4. The method for preparing the phase change coupled thermochromic regulated radiation cooling wood according to claim 1, characterized in that: After adding the polysiloxane to the polyethylene glycol acrylate solution, a Karstedt catalyst is added and the mixture is reacted at 70-90° C. for 9-11 hours to obtain a radiation cooling coupled solid-solid phase change material.

5. The method for preparing the phase change coupled thermochromic regulated radiation cooling wood according to claim 1, characterized in that: The molar ratio of dodecanol, crystal violet lactone and bisphenol A is 95-105:1:9-11.

6. The method for preparing the phase change coupled thermochromic regulated radiation cooling wood according to claim 1, characterized in that: The emulsification conditions are: temperature 55-65° C., stirring speed 3800-4200 rpm, and duration 12-18 min.

7. The method for preparing the phase change coupled thermochromic regulated radiation cooling wood according to claim 1, characterized in that: The mass ratio of the core wall material of the latex to methyl methacrylate is 0.9-1.1:1; the initiator is azobisisobutyronitrile with a mass fraction of 0.18-0.22wt%; the reaction conditions of adding methyl methacrylate and azobisisobutyronitrile into the latex after mixing are 75-85°C and 3-5h. After the reaction, the latex is filtered, washed and vacuum dried to obtain reversible thermochromic microcapsules.

8. The method for preparing the phase change coupled thermochromic regulated radiation cooling wood according to claim 1, characterized in that: The wood is high-permeability Populus cathayana.

9. The method for preparing the phase change coupled thermochromic regulated radiation cooling wood according to claim 1, characterized in that: The vacuum pressurization conditions are a pressure of 0-2 MPa and a duration of 30-90 min.

10. The method for preparing the phase change coupled thermochromic regulated radiation cooling wood according to claim 1, characterized in that: The vacuum drying conditions are a temperature of 45-55° C. and a duration of 10-14 h.

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