A bimodal polycaprolactone building energy-saving film and a preparation method thereof

Abstract

This invention relates to a dual-mode polycaprolactone (PCL) building energy-saving film and its preparation method. The dual-mode PCL building energy-saving film of this invention uses a temperature-sensitive PCL and hydrogel composite layer as the outer layer, and adds VO2-based materials. It can automatically reflect near-infrared light during high summer temperatures and automatically project sunlight during low winter temperatures; it requires no external power supply and is purely passively regulated. Furthermore, a PCL-based triboelectric nanogenerator array serves as the middle layer, which can collect mechanical energy from the building surface environment to power low-power sensors within the building, and can also connect surplus energy to the grid or store it. The transparent PCL and nanocellulose composite layer provides better mechanical support and is easy to install.

Description

Technical Field

[0001] This invention relates to the field of building film technology, and in particular to a dual-mode polycaprolactone building energy-saving film and its preparation method. Background Technology

[0002] The architectural window film market is growing rapidly, and existing products mainly have the following technological gaps: 1. Functional separation: Existing architectural films are either heat-insulating (reflecting infrared) or power-generating (photovoltaic), with few products integrating energy saving and power generation; 2. Lack of dynamic control: Although there are intelligent dimming films, most are electrochromic (requiring an external power supply) and are complicated to install; 3. Poor biodegradability: Traditional PET-based building films are difficult to recycle after disposal, causing white pollution; 4. Low building integration: It cannot achieve functional synergy with the building itself. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a dual-mode polycaprolactone building energy-saving film and its preparation method, thereby constructing an intelligent building film that does not require external power supply, can autonomously regulate the light and heat environment, and can convert and utilize excess energy.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is: a dual-mode polycaprolactone building energy-saving film, the innovation of which is: including an outer photothermal regulation layer, an intermediate energy conversion layer and an inner structural support layer; The external photothermal regulation layer has a dual-layer structure, including a thermosensitive PCL and a hydrogel composite layer; the external photothermal regulation layer contains several micro thermochromic capsules; used to achieve shading and heating according to temperature, realizing an energy-saving mode; The intermediate energy conversion layer is a PCL-based triboelectric nanogenerator array, which is used to convert wind-induced vibration or raindrop impact into electrical energy to achieve the power generation mode. The inner structural support layer is a composite layer of transparent PCL and nanocellulose, which is used to provide mechanical support and facilitate installation.

[0005] Furthermore, the micro thermochromic capsule is a VO2-based material.

[0006] Furthermore, the energy-saving mode is as follows: when the temperature is >30℃, the micro thermochromic capsule undergoes a phase change, reflects near-infrared light, and achieves a shading function with a shading coefficient SC<0.3; when the temperature is <15℃, the micro thermochromic capsule returns to a transparent state, with a solar transmittance >80%, achieving passive solar heating and realizing the heating function.

[0007] Furthermore, the power generation mode is as follows: wind pressure difference or raindrop impact on the building surface drives triboelectric nanogenerator to generate electricity; utilizing the low-temperature flexibility of PCL, the intermediate energy conversion layer is ensured to maintain high elasticity and stable power generation efficiency in low-temperature environments.

[0008] An innovative method for preparing a dual-mode polycaprolactone building energy-saving film is as follows: S1: Fabrication of the external photothermal modulation layer: S1.1: VO2 nanoparticle pretreatment (anti-agglomeration) Weigh 1–3 wt% VO2 particles and add deionized water containing 0.2 wt% SDS; disperse ultrasonically at 300 W, 40 °C, for 60 min until no visible particles are present; surface modification: add 1.5 wt% KH-550, adjust pH to 4–5, reflux at 80 °C for 2 h, centrifuge and wash with water 3 times, and vacuum dry at 60 °C for 12 h. S1.2: Preparation of PCL-PEG-PCL solution: Prepare a 15–25 wt% DCM solution using PCL-PEG-PCL, then add the PCL-PEG-PCL solid to the DCM solution and stir at 40°C for 2 hours until completely dissolved. S1.3: Preparation of thermosensitive hydrogel precursor: Weigh NIPAM (10–15 wt%) and MBA (0.8 mol%), add to deionized water; stir and dissolve in an ice bath, then purge with N2 for 30 min to remove oxygen; add APS (1 mol%), stir and dissolve, and set aside (add TEMED just before use); S1.4: Composite precursor mixing: The VO2 dispersion was slowly added dropwise to the hydrogel precursor and stirred at 30°C for 30 min; then the PCL solution was slowly added dropwise at a volume ratio of aqueous phase to organic phase of 3:1, and the mixture was sheared at 8000 rpm at 40°C for 15 min to form a homogeneous emulsion. S1.5: Film formation and crosslinking: Casting: Pour the mixture into a polytetrafluoroethylene mold; Crosslinking: Curing at 37℃ for 2 hours (NIPAM free radical polymerization + PCL phase separation); Post-treatment: Remove solvent by ventilation at room temperature for 24 hours, soak in deionized water 3 times for 30 minutes each time to remove unreacted monomers; Drying: Vacuum drying at 25℃ for 12 hours to obtain a PCL hydrogel composite layer containing VO2. S2: Preparation of the intermediate energy conversion layer: S2.1: Preparation of PCL electrospun film: Solution: 12wt%PCL (Mn=80000) / DMF, stirred at 40℃ for 2h until transparent; Electrospinning parameters: voltage 15kV, receiving distance 15cm, flow rate 1mL / h, roller receiving 100rpm; Post-treatment: annealing at 60℃ for 5min to enhance crystallization, thickness 20–50μm, fiber diameter 600nm; S2.2: Conductive electrode deposition: PEDOT:PSS (containing 5% glycerol) was drop-coated onto the surface of the PCL membrane and annealed at 120℃ for 30 min to achieve a conductivity of 0.65 mS / cm. S2.3: Single TENG unit assembly: The assembly consists of a PCL fiber membrane (positively charged), a PDMS microstructure layer (negatively charged), and electrodes. S2.4: Array Integration: Substrate: The PCL flexible film is laser-cut into several units, and each unit is led out with an electrode and connected to the flexible PCB, with the common terminal grounded; then it is thermo-pressed and encapsulated. S3: Fabrication of the internal structural support layer: S3.1. Surface grafting treatment is performed on nanocellulose to obtain modified nanocellulose; S3.2. Mix modified nanocellulose, polycaprolactone, and solvent to obtain a slurry; S3.3. The slurry is melt-blended and granulated to obtain composite granules; S3.4. The composite granules, metal soap stabilizers and natural resin derivatives are melt-blended and granulated to obtain polycaprolactone-based composite materials; S4: The outer photothermal control layer, the intermediate energy conversion layer and the inner structural support layer are co-extruded.

[0009] The advantages of this invention are: 1) The dual-mode polycaprolactone building energy-saving film of the present invention uses a temperature-sensitive PCL and hydrogel composite layer as the outer layer and adds VO2-based materials, which can automatically reflect near-infrared light when the temperature is high in summer and automatically project sunlight when the temperature is low in winter; it does not require external power supply and is purely passively regulated; in addition, the PCL-based triboelectric nanogenerator array as the middle layer can collect mechanical energy from the building surface environment to power low-power sensors inside the building, and can also connect the surplus electricity to the grid or store it; the transparent PCL and nanocellulose composite layer can provide better mechanical support and is easy to install. Attached Figure Description

[0010] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0011] Figure 1 This invention relates to a process for preparing the external photothermal control layer of a dual-mode polycaprolactone building energy-saving film.

[0012] Figure 2 This invention relates to a process for preparing the intermediate energy conversion layer of a dual-mode polycaprolactone building energy-saving film.

[0013] Figure 3 This invention relates to a process for preparing the internal structural support layer of a dual-mode polycaprolactone building energy-saving film. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0015] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0016] like Figures 1 to 3 The diagram shows a dual-mode polycaprolactone building energy-saving film, comprising an outer photothermal regulation layer, an intermediate energy conversion layer, and an inner structural support layer.

[0017] The external photothermal regulation layer has a dual-layer structure, including a thermosensitive PCL and a hydrogel composite layer; the external photothermal regulation layer contains several micro thermochromic capsules; these are used to achieve shading and heating based on temperature, thus realizing an energy-saving mode.

[0018] The intermediate energy conversion layer is a PCL-based triboelectric nanogenerator array, which is used to convert wind-induced vibration or raindrop impact into electrical energy to achieve the power generation mode.

[0019] The inner structural support layer is a composite layer of transparent PCL and nanocellulose, which is used to provide mechanical support and facilitate installation.

[0020] The micro thermochromic capsules are made of VO2-based materials.

[0021] The energy-saving mode is as follows: when the temperature is >30℃, the micro thermochromic capsule undergoes a phase change, reflects near-infrared light, and achieves shading function with a shading coefficient SC<0.3; when the temperature is <15℃, the micro thermochromic capsule returns to a transparent state, and the solar transmittance is >80%, achieving passive solar heating and realizing heating function.

[0022] The power generation model is as follows: the wind pressure difference or raindrop impact on the building surface drives the triboelectric nanogenerator to generate electricity; the low-temperature flexibility of PCL ensures that the intermediate energy conversion layer remains highly elastic and the power generation efficiency is stable in low-temperature environments.

[0023] A method for preparing a dual-mode polycaprolactone building energy-saving film, the specific preparation method is as follows: S1: Fabrication of the external photothermal modulation layer: S1.1: VO2 nanoparticle pretreatment (anti-agglomeration) Weigh 1–3 wt% VO2 particles and add deionized water containing 0.2 wt% SDS; disperse ultrasonically at 300 W, 40 °C, for 60 min until no visible particles are present; surface modification: add 1.5 wt% KH-550, adjust pH to 4–5, reflux at 80 °C for 2 h, centrifuge and wash with water 3 times, and vacuum dry at 60 °C for 12 h. S1.2: Preparation of PCL-PEG-PCL solution: Prepare a 15–25 wt% DCM solution using PCL-PEG-PCL, then add the PCL-PEG-PCL solid to the DCM solution and stir at 40°C for 2 hours until completely dissolved. S1.3: Preparation of thermosensitive hydrogel precursor: Weigh NIPAM (10–15 wt%) and MBA (0.8 mol%), add to deionized water; stir and dissolve in an ice bath, then purge with N2 for 30 min to remove oxygen; add APS (1 mol%), stir and dissolve, and set aside (add TEMED just before use); S1.4: Composite precursor mixing: The VO2 dispersion was slowly added dropwise to the hydrogel precursor and stirred at 30°C for 30 min; then the PCL solution was slowly added dropwise at a volume ratio of aqueous phase to organic phase of 3:1, and the mixture was sheared at 8000 rpm at 40°C for 15 min to form a homogeneous emulsion. S1.5: Film formation and crosslinking: Casting: Pour the mixture into a polytetrafluoroethylene mold; Crosslinking: Curing at 37℃ for 2 hours (NIPAM free radical polymerization + PCL phase separation); Post-treatment: Remove solvent by ventilation at room temperature for 24 hours, soak in deionized water 3 times for 30 minutes each time to remove unreacted monomers; Drying: Vacuum drying at 25℃ for 12 hours to obtain a PCL hydrogel composite layer containing VO2. S2: Preparation of the intermediate energy conversion layer: S2.1: Preparation of PCL electrospun film: Solution: 12wt%PCL (Mn=80000) / DMF, stirred at 40℃ for 2h until transparent; Electrospinning parameters: voltage 15kV, receiving distance 15cm, flow rate 1mL / h, roller receiving 100rpm; Post-treatment: annealing at 60℃ for 5min to enhance crystallization, thickness 20–50μm, fiber diameter 600nm; S2.2: Conductive electrode deposition: PEDOT:PSS (containing 5% glycerol) was drop-coated onto the surface of the PCL membrane and annealed at 120℃ for 30 min to achieve a conductivity of 0.65 mS / cm. S2.3: Single TENG unit assembly: The assembly consists of a PCL fiber membrane (positively charged), a PDMS microstructure layer (negatively charged), and electrodes. S2.4: Array Integration: Substrate: The PCL flexible film is laser-cut into several units, and each unit is led out with an electrode and connected to the flexible PCB, with the common terminal grounded; then it is thermo-pressed and encapsulated. S3: Fabrication of the internal structural support layer: S3.1. Surface grafting treatment is performed on nanocellulose to obtain modified nanocellulose; S3.2. Mix modified nanocellulose, polycaprolactone, and solvent to obtain a slurry; S3.3. The slurry is melt-blended and granulated to obtain composite granules; S3.4. The composite granules, metal soap stabilizers and natural resin derivatives are melt-blended and granulated to obtain polycaprolactone-based composite materials; S4: The outer photothermal control layer, the intermediate energy conversion layer and the inner structural support layer are co-extruded.

[0024] Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A dual-mode polycaprolactone building energy-saving film, characterized in that: It includes an outer photothermal control layer, an intermediate energy conversion layer, and an inner structural support layer; The external photothermal regulation layer has a dual-layer structure, including a thermosensitive PCL and a hydrogel composite layer; the external photothermal regulation layer contains several micro thermochromic capsules; used to achieve shading and heating according to temperature, realizing an energy-saving mode; The intermediate energy conversion layer is a PCL-based triboelectric nanogenerator array, which is used to convert wind-induced vibration or raindrop impact into electrical energy to achieve the power generation mode. The inner structural support layer is a composite layer of transparent PCL and nanocellulose, which is used to provide mechanical support and facilitate installation.

2. The dual-mode polycaprolactone building energy-saving film according to claim 1, characterized in that: The micro thermochromic capsules are made of VO2-based materials.

3. The dual-mode polycaprolactone building energy-saving film according to claim 1, characterized in that: The energy-saving mode is as follows: when the temperature is >30℃, the micro thermochromic capsule undergoes a phase change, reflects near-infrared light, and achieves shading function with a shading coefficient SC<0.3; when the temperature is <15℃, the micro thermochromic capsule returns to a transparent state, and the solar transmittance is >80%, achieving passive solar heating and realizing heating function.

4. The dual-mode polycaprolactone building energy-saving film according to claim 1, characterized in that: The power generation mode is as follows: wind pressure difference or raindrop impact on the building surface drives the triboelectric nanogenerator to generate electricity; the low-temperature flexibility of PCL ensures that the intermediate energy conversion layer remains highly elastic and the power generation efficiency is stable in low-temperature environments.

5. A method for preparing a dual-mode polycaprolactone building energy-saving film, characterized in that: The specific preparation method is as follows: S1: Fabrication of the external photothermal modulation layer: S1.1: VO2 nanoparticle pretreatment (anti-agglomeration) Weigh 1–3 wt% VO2 particles and add them to deionized water containing 0.2 wt% SDS; disperse using ultrasonication: 300 W, 40 °C, 60 min, until no visible particles remain. Surface modification: Add 1.5wt% KH-550, adjust pH to 4–5, reflux at 80℃ for 2h, centrifuge and wash with water 3 times, and vacuum dry at 60℃ for 12h; S1.2: Preparation of PCL-PEG-PCL solution: Prepare a 15–25 wt% DCM solution using PCL-PEG-PCL, then add the PCL-PEG-PCL solid to the DCM solution; stir at 40°C for 2 hours until completely dissolved. S1.3: Preparation of thermosensitive hydrogel precursor: Weigh NIPAM (10–15 wt%) and MBA (0.8 mol%), add to deionized water; stir and dissolve in an ice bath, then purge with N2 for 30 min to remove oxygen; add APS (1 mol%), stir and dissolve, and set aside (add TEMED just before use); S1.4: Composite precursor mixing: The VO2 dispersion was slowly added dropwise to the hydrogel precursor and stirred at 30°C for 30 min; then the PCL solution was slowly added dropwise at a volume ratio of aqueous phase to organic phase of 3:1, and the mixture was sheared at 8000 rpm at 40°C for 15 min to form a homogeneous emulsion. S1.5: Film formation and crosslinking: Casting: Pour the mixture into a polytetrafluoroethylene mold; Crosslinking: Curing at 37℃ for 2 hours (NIPAM free radical polymerization + PCL phase separation); Post-treatment: Solvent removal by ventilation at room temperature for 24 hours, soaking in deionized water 3 times for 30 minutes each time to remove unreacted monomers; Drying: Vacuum drying at 25℃ for 12 hours to obtain a PCL hydrogel composite layer containing VO2. S2: Preparation of the intermediate energy conversion layer: S2.1: Preparation of PCL electrospun film: Solution: 12wt%PCL (Mn=80000) / DMF, stirred at 40℃ for 2h until transparent; Electrospinning parameters: voltage 15kV, receiving distance 15cm, flow rate 1mL / h, roller receiving 100rpm; Post-treatment: annealing at 60℃ for 5min to enhance crystallization, thickness 20–50μm, fiber diameter 600nm; S2.2: Conductive electrode deposition: PEDOT:PSS (containing 5% glycerol) was drop-coated onto the surface of the PCL membrane and annealed at 120℃ for 30 min to achieve a conductivity of 0.65 mS / cm. S2.3: Single TENG unit assembly: The assembly consists of a PCL fiber membrane (positively charged), a PDMS microstructure layer (negatively charged), and electrodes. S2.4: Array Integration: Substrate: The PCL flexible film is laser-cut into several units, and each unit is led out with an electrode and connected to the flexible PCB, with the common terminal grounded; then it is thermo-pressed and encapsulated. S3: Fabrication of the internal structural support layer: S3.

1. Surface grafting treatment is performed on nanocellulose to obtain modified nanocellulose; S3.

2. Mix modified nanocellulose, polycaprolactone, and solvent to obtain a slurry; S3.

3. The slurry is melt-blended and granulated to obtain composite granules; S3.

4. The composite granules, metal soap stabilizers and natural resin derivatives are melt-blended and granulated to obtain polycaprolactone-based composite materials; S4: The outer photothermal control layer, the intermediate energy conversion layer and the inner structural support layer are co-extruded.

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