Preparation method of biomass polyurethane substrate layer CuS photo-thermal composite film

Abstract

The invention discloses a preparation method of a biomass polyurethane substrate layer CuS photo-thermal composite film. The preparation method comprises the following steps: step 1, preparing a biomass waterborne polyurethane emulsion; step 2, preparing a lamellar CuS nano functional filler; and 3, uniformly mixing and stirring the lamellar CuS nano functional filler prepared in the step 2 and the biomass waterborne polyurethane emulsion prepared in the step 1, and carrying out ultrasonic dispersion, vacuum defoaming and film casting treatment to obtain the biomass polyurethane substrate layer CuS photo-thermal composite film. The invention further discloses the biomass polyurethane substrate layer CuS photo-thermal composite film and application thereof. The invention solves the problem that the existing waterborne polyurethane depends on a petroleum-based raw material and is not effectively compounded with a lamellar CuS nano functional filler, so that the efficient photo-thermal conversion function is lacked.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite material technology, specifically relating to biomass polyurethane substrate CuS photothermal composite film, and also to the preparation method and application of biomass polyurethane substrate CuS photothermal composite film. Background Technology

[0002] Waterborne polyurethane (WPU), using water as the dispersion medium, possesses significant advantages such as good flexibility, ease of storage, convenient use, and safety and environmental friendliness. It has been widely applied in various fields including coatings, fabric coatings, and biomedical materials, becoming one of the current research hotspots in the field of polymer materials. However, the main raw materials (polyols, isocyanates) of traditional waterborne polyurethanes in existing technologies are mostly derived from non-renewable petrochemical products. With the intensification of the global energy crisis and the increasing awareness of environmental protection, these materials relying on fossil resources can no longer meet the needs of sustainable development. Furthermore, traditional waterborne polyurethanes typically only provide basic physical protection and adhesion, lacking photothermal conversion capabilities, and cannot meet the multifunctional requirements of coating materials in the energy sector.

[0003] Bone glue (BG), a product of partial hydrolysis of collagen, possesses excellent biocompatibility, biodegradability, film-forming properties, and adhesiveness, and has been widely used in adhesives, food additives, and high-performance medical materials. Its molecular chain is rich in active groups such as amino and carboxyl groups, which can react with isocyanates to form the hard segments of the polyurethane backbone. This provides an ideal biomass raw material for the synthesis of environmentally friendly biomass-based waterborne polyurethane, enabling not only the resource utilization of biomass materials but also effectively reducing dependence on petrochemical raw materials and lowering environmental pollution. Copper sulfide (CuS) nanoparticles, due to their strong light absorption characteristics and high photothermal conversion efficiency in the near-infrared wavelength range, as well as their low cost, have become a class of high-performance photothermal conversion materials. Among them, copper sulfide nanoparticles with a layered structure, with their unique high specific surface area, can significantly enhance the material's ability to capture incident light, further improving its comprehensive performance in photothermal applications and showing broad application prospects in photothermal conversion-related fields.

[0004] In summary, existing waterborne polyurethanes suffer from dependence on petroleum-based raw materials and lack of photothermal properties. While biomass modification improves environmental friendliness, it still lacks photothermal performance. The photothermal advantages of layered CuS have not been effectively applied to biomass-based waterborne polyurethanes, and the synergistic improvement of nanofiller dispersibility and material properties remains an unsolved technical challenge. Summary of the Invention

[0005] The primary objective of this invention is to provide a biomass polyurethane substrate CuS photothermal composite film, which solves the problem that current waterborne polyurethanes rely on petroleum-based raw materials and lack efficient photothermal conversion capabilities.

[0006] The second objective of this invention is to provide a method for preparing a biomass polyurethane substrate CuS photothermal composite film.

[0007] The third objective of this invention is to provide the application of biomass polyurethane substrate CuS photothermal composite films.

[0008] The first technical solution adopted in this invention is a method for preparing a biomass polyurethane substrate CuS photothermal composite film, comprising the following steps:

[0009] Step 1: Prepare a biomass-based aqueous polyurethane emulsion; Step 2: Prepare layered CuS nano-functional fillers; Step 3: Mix the layered CuS nano-functional filler obtained in Step 2 with the biomass aqueous polyurethane emulsion obtained in Step 1, stir evenly, and then perform ultrasonic dispersion, vacuum defoaming and casting film treatment to obtain a biomass polyurethane-based layered CuS photothermal composite film.

[0010] The first technical solution of the present invention is further characterized in that, Step one is as follows: Weigh 4-5 parts by weight of polytrimethylene ether glycol, 4.5-5 parts by weight of isophorone diisocyanate, and 0.5-1 parts by weight of dibutyltin dilaurate into a reaction vessel and react at 70-80 °C for 2-3 hours to obtain a polyurethane prepolymer. Then, dissolve 0.5-1 parts by weight of dimethylolpropionic acid in 3-5 ml of N-methylpyrrolidone and add it to the polyurethane prepolymer. Stir continuously in an oil bath at 60-70 °C for 2-2.5 hours. Further cool to below 40 °C, then add 1.5-2 parts by weight of triethylamine and react for 20-30 minutes to obtain a polyurethane prepolymer mixture neutralized by triethylamine. Separately, dissolve 1-1.5 parts by weight of bone glue in 40-50 parts by weight of water and stir at 60-70 °C for 30 minutes until completely dissolved. Then cool to 30-40 °C. At ℃, a bone glue aqueous solution was prepared; the bone glue aqueous solution was added to the above-mentioned polyurethane prepolymer mixture neutralized with triethylamine, and high-speed shear emulsification was carried out for 30-40 min to obtain a biomass aqueous polyurethane emulsion.

[0011] Step two is as follows: First, weigh 0.5-1 part of polyvinylpyrrolidone and dissolve it in 50-80 ml of deionized water, stirring at 25-30 ℃ for 30-40 min; then add 0.6-0.8 g of copper chloride dihydrate and 0.3-0.4 g of thiourea sequentially, and continue stirring for 30 min; slowly add 1-3 parts by weight of ammonia water, stirring at 25-30 ℃ for 2-3 h to obtain the precursor solution; transfer the precursor solution to a 100 ml stainless steel high-pressure reactor lined with polytetrafluoroethylene, and react at 140-160 ℃ for 4-6 h. After the reaction, allow it to cool naturally to room temperature to obtain a dark green suspension; transfer the dark green suspension to a centrifuge tube, centrifuge at 8000 rpm for 10-15 min, and discard the supernatant; wash the precipitate alternately with deionized water and anhydrous ethanol 3-5 times each; dry the washed precipitate under vacuum at 50-60 ℃ for 6-8 hours. h, to obtain layered CuS nanofunctional fillers.

[0012] Step three specifically involves: Step 3.1: Weigh 0.05-0.1 parts by weight of the prepared layered CuS nano-functional filler and 15-20 parts by weight of the biomass aqueous polyurethane emulsion prepared in step one into a container, stir at room temperature for 60-70 min to obtain a composite emulsion. Step 3.2: The composite emulsion is ultrasonicated for 30-40 min at a power of 200-500 W and a frequency of 40 kHz to obtain an ultrasonically dispersed emulsion. The ultrasonically dispersed emulsion is then uniformly cast into a horizontal polytetrafluoroethylene mold and allowed to stand for 10-20 min under a vacuum of -0.095 MPa to -0.1 MPa to remove bubbles, resulting in a defoamed emulsion. The defoamed mold is then transferred to a horizontal worktable and allowed to stand at room temperature for 2-3 days to obtain a biomass polyurethane substrate CuS photothermal composite film.

[0013] The second technical solution adopted in this invention is a biomass polyurethane substrate CuS photothermal composite film, which is prepared using the same method as the biomass polyurethane substrate CuS photothermal composite film.

[0014] The third technical solution adopted in this invention is the application of biomass polyurethane substrate CuS photothermal composite film in the fields of flexible photothermal conversion, biomass-based functional coatings and energy-saving and environmentally friendly functional materials.

[0015] The beneficial effects of this invention are: This invention successfully prepared a photothermal biomass-based waterborne polyurethane with excellent photothermal and mechanical properties by using layered CuS nanoparticles as a highly efficient photothermal functional filler and biomass bone glue as a multi-hydrogen-bonded functional monomer. The amino groups on the bone glue molecules can form urea bonds with isocyanate groups and construct a multi-level hydrogen bond structure, significantly improving the mechanical properties of the waterborne polyurethane. Secondly, the layered CuS nanoparticles possess strong near-infrared light absorption and a high specific surface area, endowing the material with excellent photothermal conversion capabilities. Under standard solar irradiation of 1000 W / m², the temperature can rise by 15 °C within 300 seconds, demonstrating rapid photothermal response and high conversion efficiency. This invention replaces some petroleum-based components with renewable biomass raw materials, making it green, environmentally friendly, and highly biodegradable. It helps alleviate dependence on petrochemical resources and environmental pollution problems, truly realizing the high-value utilization of biomass materials. This material combines excellent mechanical properties, high-efficiency photothermal conversion, and green sustainability, and has broad application prospects in flexible photothermal devices, biomedical materials, functional coatings, energy conservation and environmental protection, which is highly in line with the current industrial trend of energy conservation, environmental protection and sustainable development. Attached Figure Description

[0016] Figure 1 This is a comparison diagram of the photothermal performance of the biomass polyurethane substrate CuS photothermal composite film of the present invention and the traditional biomass waterborne polyurethane film. Detailed Implementation The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0017] This invention provides a method for preparing a biomass polyurethane substrate CuS photothermal composite film, comprising the following steps: Step 1: Prepare a biomass-based aqueous polyurethane emulsion; Step one is as follows: Weigh 4-5 parts by weight of polytrimethylene ether glycol, 4.5-5 parts by weight of isophorone diisocyanate, and 0.5-1 parts by weight of dibutyltin dilaurate into a reaction vessel and react at 70-80 °C for 2-3 hours to obtain a polyurethane prepolymer. Then, dissolve 0.5-1 parts by weight of dimethylolpropionic acid in 3-5 ml of N-methylpyrrolidone and add it to the polyurethane prepolymer. Stir continuously in an oil bath at 60-70 °C for 2-2.5 hours. Further cool to below 40 °C, then add 1.5-2 parts by weight of triethylamine and react for 20-30 minutes to obtain a polyurethane prepolymer mixture neutralized by triethylamine. Separately, dissolve 1-1.5 parts by weight of bone glue in 40-50 parts by weight of water and stir at 60-70 °C for 30 minutes until completely dissolved. Then cool to 30-40 °C. At ℃, a bone glue aqueous solution was prepared; the bone glue aqueous solution was added to the above-mentioned polyurethane prepolymer mixture neutralized with triethylamine, and high-speed shear emulsification was carried out for 30-40 min to obtain a biomass aqueous polyurethane emulsion.

[0018] Step 2: Prepare layered CuS nano-functional fillers; Step two specifically involves: first, preparing a precursor solution, then subjecting the precursor solution to a hydrothermal reaction to obtain a dark green suspension, and finally obtaining a layered CuS nanofunctional filler by solid-liquid separation, washing, and drying of the dark green suspension.

[0019] The precursor solution preparation steps are as follows: Weigh 0.5-1 part of polyvinylpyrrolidone and dissolve it in 50-80 ml of deionized water, and stir at 25-30 ℃ for 30-40 min; add 0.6-0.8 g of copper chloride dihydrate and 0.3-0.4 g of thiourea in sequence and continue stirring for 30 min; slowly add 1-3 parts by weight of ammonia water, and stir at 25-30 ℃ for 2-3 h to obtain the precursor solution.

[0020] The hydrothermal reaction is as follows: the precursor solution is transferred to a 100 ml stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 140-160 ℃ for 4-6 h. After the reaction, it is naturally cooled to room temperature to obtain a dark green suspension. The dark green suspension is transferred to a centrifuge tube and centrifuged at 8000 rpm for 10-15 min, and the supernatant is discarded. The precipitate is washed 3-5 times each with deionized water and anhydrous ethanol. The washed precipitate is dried under vacuum at 50-60 ℃ for 6-8 h to obtain layered CuS nanofunctional filler.

[0021] Step 3: Mix the layered CuS nano-functional filler obtained in Step 2 with the biomass aqueous polyurethane emulsion obtained in Step 1, stir evenly, and then perform ultrasonic dispersion, vacuum defoaming and casting film treatment to obtain a biomass polyurethane-based layered CuS photothermal composite film.

[0022] Step three specifically involves: Step 3.1: Prepare a composite emulsion of layered CuS nanofunctional filler and biomass aqueous polyurethane emulsion; Step 3.1 is as follows: Weigh 0.05-0.1 parts by weight of the prepared layered CuS nanofunctional filler and 15-20 parts by weight of the biomass aqueous polyurethane emulsion prepared in step one into a container, stir at room temperature for 60-70 min to obtain a composite emulsion.

[0023] Step 3.2: The composite emulsion is subjected to ultrasonic dispersion treatment. After ultrasonic treatment, the emulsion is defoamed under vacuum and cast into a film to obtain a biomass polyurethane substrate CuS photothermal composite film.

[0024] Step 3.2 is as follows: The composite emulsion is ultrasonicated for 30-40 minutes at a power of 200-500 W and a frequency of 40 kHz to obtain an ultrasonically dispersed emulsion. The ultrasonically dispersed emulsion is then uniformly cast into a horizontal polytetrafluoroethylene mold and allowed to stand for 10-20 minutes under a vacuum of -0.095 MPa to -0.1 MPa to remove bubbles, resulting in a defoamed emulsion. The defoamed mold is then transferred to a horizontal worktable and allowed to stand at room temperature for 2-3 days to obtain a biomass polyurethane substrate CuS photothermal composite film.

[0025] The present invention also provides a biomass polyurethane substrate CuS photothermal composite film, which is prepared by the above-mentioned preparation method of biomass polyurethane substrate CuS photothermal composite film.

[0026] This invention also provides the application of biomass polyurethane substrate CuS photothermal composite film in the fields of flexible photothermal conversion, biomass-based functional coatings and energy-saving and environmentally friendly functional materials.

[0027] Example 1 This embodiment provides a method for preparing a biomass polyurethane substrate CuS photothermal composite film, specifically as follows: Step 1: Prepare a biomass-based aqueous polyurethane emulsion; Four parts by weight of polytrimethylene ether glycol, 4.5 parts by weight of isophorone diisocyanate, and 0.5 parts by weight of dibutyltin dilaurate were weighed and added to a reaction vessel. The mixture was reacted at 70 °C for 2 h to obtain a polyurethane prepolymer. Then, 0.5 parts by weight of dimethylolpropionic acid was dissolved in 3 ml of N-methylpyrrolidone and added to the polyurethane prepolymer. The mixture was stirred continuously at 60 °C in an oil bath for 2 h. The temperature was further lowered to below 40 °C, and then 1.5 parts by weight of triethylamine was added and reacted for 20 min to obtain a polyurethane prepolymer mixture neutralized by triethylamine. Separately, 1 part by weight of bone glue was dissolved in 40 parts by weight of water and stirred at 60 °C for 30 min. After complete dissolution, the temperature was lowered to 30 °C to obtain a bone glue aqueous solution. The bone glue aqueous solution was added to the above polyurethane prepolymer mixture neutralized by triethylamine and emulsified by high-speed shearing for 30 min to obtain a biomass aqueous polyurethane emulsion.

[0028] Step 2: Prepare layered CuS nano-functional fillers; First, a precursor solution is prepared. The precursor solution is subjected to a hydrothermal reaction to obtain a dark green suspension. After solid-liquid separation, washing, and drying, the dark green suspension is used to obtain a layered CuS nanofunctional filler. The precursor solution preparation steps are as follows: Weigh 0.5 parts of polyvinylpyrrolidone and dissolve it in 50 ml of deionized water, and stir at 25℃ for 30 min; add 0.6 g of copper chloride dihydrate and 0.3 g of thiourea in sequence and continue stirring for 30 min; slowly add 1 part by weight of ammonia water, and stir at 25℃ for 2 h to obtain the precursor solution; The hydrothermal reaction was carried out as follows: the precursor solution was transferred to a 100 ml stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 140 °C for 4 h. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a dark green suspension. The dark green suspension was transferred to a centrifuge tube and centrifuged at 8000 rpm for 10 min, and the supernatant was discarded. The precipitate was washed three times each with deionized water and anhydrous ethanol. The washed precipitate was dried under vacuum at 50 °C for 6 h to obtain a layered CuS nanofunctional filler.

[0029] Step 3 Step 3.1: Prepare a composite emulsion of layered CuS nanofunctional filler and biomass aqueous polyurethane emulsion; Step 3.2: The composite emulsion is subjected to ultrasonic dispersion treatment. After ultrasonic treatment, the emulsion is subjected to vacuum defoaming and casting film treatment to obtain a biomass polyurethane substrate CuS photothermal composite film. Step 3.1 is as follows: Weigh 0.05 parts by weight of the prepared layered CuS nanofunctional filler and 15 parts by weight of the biomass aqueous polyurethane emulsion prepared in step one and add them to a container. Stir at room temperature for 60 min to obtain a composite emulsion. Step 3.2 is as follows: The composite emulsion is ultrasonicated for 30 min at a power of 200 W and a frequency of 40 kHz to obtain an ultrasonically dispersed emulsion. The ultrasonically dispersed emulsion is then uniformly cast into a horizontal polytetrafluoroethylene mold and allowed to stand for 10 min under a vacuum of -0.095 MPa to remove bubbles, resulting in a defoamed emulsion. The defoamed mold is then moved to a horizontal worktable and allowed to stand at room temperature for 2 days to obtain a biomass polyurethane substrate CuS photothermal composite film.

[0030] Example 2 This embodiment provides a method for preparing a biomass polyurethane substrate CuS photothermal composite film, specifically as follows: Step 1: Prepare a biomass-based aqueous polyurethane emulsion; Five parts by weight of polytrimethylene ether glycol, five parts by weight of isophorone diisocyanate, and one part by weight of dibutyltin dilaurate were weighed and added to a reaction vessel. The mixture was reacted at 80 °C for 3 h to obtain a polyurethane prepolymer. Then, one part by weight of dimethylolpropionic acid was dissolved in 5 ml of N-methylpyrrolidone and added to the polyurethane prepolymer. The mixture was stirred continuously in an oil bath at 70 °C for 2.5 h. The temperature was further lowered to 30 °C, and then two parts by weight of triethylamine were added and reacted for 30 min to obtain a polyurethane prepolymer mixture neutralized by triethylamine. Separately, 1.5 parts by weight of bone glue was dissolved in 50 parts by weight of water and stirred at 70 °C for 30 min. After complete dissolution, the temperature was lowered to 40 °C to obtain a bone glue aqueous solution. The bone glue aqueous solution was added to the above polyurethane prepolymer mixture neutralized by triethylamine and emulsified by high-speed shearing for 40 min to obtain a biomass aqueous polyurethane emulsion.

[0031] Step 2: Prepare layered CuS nano-functional fillers; First, a precursor solution is prepared. The precursor solution is subjected to a hydrothermal reaction to obtain a dark green suspension. After solid-liquid separation, washing, and drying, the dark green suspension is used to obtain a layered CuS nanofunctional filler. The precursor solution preparation steps are as follows: Weigh 1 part of polyvinylpyrrolidone and dissolve it in 80 ml of deionized water, and stir at 30 ℃ for 40 min; add 0.8 g of copper chloride dihydrate and 0.4 g of thiourea in sequence and continue stirring for 30 min; slowly add 3 parts by weight of ammonia water, and stir at 30 ℃ for 3 h to obtain the precursor solution; The hydrothermal reaction was carried out as follows: the precursor solution was transferred to a 100 ml stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 160 °C for 6 h. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a dark green suspension. The dark green suspension was transferred to a centrifuge tube and centrifuged at 8000 rpm for 15 min, and the supernatant was discarded. The precipitate was washed 5 times each with deionized water and anhydrous ethanol. The washed precipitate was dried under vacuum at 60 °C for 8 h to obtain a layered CuS nanofunctional filler.

[0032] Step 3 Step 3.1: Prepare a composite emulsion of layered CuS nanofunctional filler and biomass aqueous polyurethane emulsion; Step 3.2: The composite emulsion is subjected to ultrasonic dispersion treatment. After ultrasonic treatment, the emulsion is subjected to vacuum defoaming and casting film treatment to obtain a biomass polyurethane substrate CuS photothermal composite film. Step 3.1 is as follows: Weigh 0.1 parts by weight of the prepared layered CuS nanofunctional filler and 20 parts by weight of the biomass aqueous polyurethane emulsion prepared in step one and add them to a container. Stir at room temperature for 70 min to obtain a composite emulsion. Step 3.2 is as follows: The composite emulsion is ultrasonicated for 40 min at a power of 500 W and a frequency of 40 kHz to obtain an ultrasonically dispersed emulsion. The ultrasonically dispersed emulsion is then uniformly cast into a horizontal polytetrafluoroethylene mold and allowed to stand for 20 min under a vacuum of -0.1 MPa to remove bubbles, resulting in a defoamed emulsion. The defoamed mold is then moved to a horizontal worktable and allowed to stand at room temperature for 3 days to obtain a biomass polyurethane substrate CuS photothermal composite film.

[0033] Example 3 This embodiment provides a method for preparing a biomass polyurethane substrate CuS photothermal composite film, specifically as follows: Step 1: Prepare a biomass-based aqueous polyurethane emulsion; 4.5 parts by weight of polytrimethylene ether glycol, 4.8 parts by weight of isophorone diisocyanate, and 0.8 parts by weight of dibutyltin dilaurate were weighed and added to a reaction vessel. The mixture was reacted at 75 °C for 2.5 h to obtain a polyurethane prepolymer. Then, 0.8 parts by weight of dimethylolpropionic acid was dissolved in 4 ml of N-methylpyrrolidone and added to the polyurethane prepolymer. The mixture was stirred continuously in an oil bath at 65 °C for 2.2 h. The temperature was further lowered to 35 °C, and then 1.8 parts by weight of triethylamine was added and reacted for 25 min to obtain a polyurethane prepolymer mixture neutralized by triethylamine. Separately, 1.2 parts by weight of bone glue was dissolved in 45 parts by weight of water and stirred at 65 °C for 30 min. After complete dissolution, the temperature was lowered to 35 °C to obtain a bone glue aqueous solution. The bone glue aqueous solution was added to the above polyurethane prepolymer mixture neutralized by triethylamine and emulsified by high-speed shearing for 35 min to obtain a biomass aqueous polyurethane emulsion.

[0034] Step 2: Prepare layered CuS nano-functional fillers; First, a precursor solution is prepared. The precursor solution is subjected to a hydrothermal reaction to obtain a dark green suspension. After solid-liquid separation, washing, and drying, the dark green suspension is used to obtain a layered CuS nanofunctional filler. The precursor solution preparation steps are as follows: Weigh 0.8 parts of polyvinylpyrrolidone and dissolve it in 65 ml of deionized water, and stir at 28℃ for 35 min; add 0.7 g of copper chloride dihydrate and 0.35 g of thiourea in sequence and continue stirring for 30 min; slowly add 2 parts by weight of ammonia water, and stir at 28℃ for 2.5 h to obtain the precursor solution; The hydrothermal reaction was carried out as follows: the precursor solution was transferred to a 100 ml stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 150 °C for 5 h. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a dark green suspension. The dark green suspension was transferred to a centrifuge tube and centrifuged at 8000 rpm for 12 min, and the supernatant was discarded. The precipitate was washed four times each with deionized water and anhydrous ethanol. The washed precipitate was dried under vacuum at 55 °C for 7 h to obtain a layered CuS nanofunctional filler.

[0035] Step 3 Step 3.1: Prepare a composite emulsion of layered CuS nanofunctional filler and biomass aqueous polyurethane emulsion; Step 3.2: The composite emulsion is subjected to ultrasonic dispersion treatment. After ultrasonic treatment, the emulsion is subjected to vacuum defoaming and casting film treatment to obtain a biomass polyurethane substrate CuS photothermal composite film. Step 3.1 is as follows: Weigh 0.08 parts by weight of the prepared layered CuS nanofunctional filler and 18 parts by weight of the biomass aqueous polyurethane emulsion prepared in step one and add them to a container. Stir at room temperature for 65 min to obtain a composite emulsion. Step 3.2 is as follows: The composite emulsion is ultrasonicated for 35 minutes at a power of 350 W and a frequency of 40 kHz to obtain an ultrasonically dispersed emulsion. The ultrasonically dispersed emulsion is then uniformly cast into a horizontal polytetrafluoroethylene mold and allowed to stand for 15 minutes under a vacuum of -0.097 MPa to remove bubbles, resulting in a defoamed emulsion. The defoamed mold is then moved to a horizontal worktable and allowed to stand at room temperature for 2.5 days to obtain a biomass polyurethane substrate CuS photothermal composite film.

[0036] Example 4 This embodiment provides a method for preparing a biomass polyurethane substrate CuS photothermal composite film, specifically as follows: Step 1: Prepare a biomass-based aqueous polyurethane emulsion; Four parts by weight of polytrimethylene ether glycol, five parts by weight of isophorone diisocyanate, and 0.5 parts by weight of dibutyltin dilaurate were weighed and added to a reaction vessel. The mixture was reacted at 70 °C for 3 h to obtain a polyurethane prepolymer. Then, one part by weight of dimethylolpropionic acid was dissolved in 3 ml of N-methylpyrrolidone and added to the polyurethane prepolymer. The mixture was stirred continuously at 60 °C in an oil bath for 2.5 h. The temperature was further lowered to 30 °C, and then 1.5 parts by weight of triethylamine was added and reacted for 30 min to obtain a polyurethane prepolymer mixture neutralized by triethylamine. Separately, 1.5 parts by weight of bone glue was dissolved in 40 parts by weight of water and stirred at 60 °C for 30 min. After complete dissolution, the temperature was lowered to 30 °C to obtain a bone glue aqueous solution. The bone glue aqueous solution was added to the above polyurethane prepolymer mixture neutralized by triethylamine and emulsified by high-speed shearing for 40 min to obtain a biomass aqueous polyurethane emulsion.

[0037] Step 2: Prepare layered CuS nano-functional fillers; First, a precursor solution is prepared. The precursor solution is subjected to a hydrothermal reaction to obtain a dark green suspension. After solid-liquid separation, washing, and drying, the dark green suspension is used to obtain a layered CuS nanofunctional filler. The precursor solution preparation steps are as follows: Weigh 0.5 parts of polyvinylpyrrolidone and dissolve it in 80 ml of deionized water, and stir at 25℃ for 40 min; add 0.6 g of copper chloride dihydrate and 0.4 g of thiourea in sequence and continue stirring for 30 min; slowly add 3 parts by weight of ammonia water, and stir at 25℃ for 3 h to obtain the precursor solution; The hydrothermal reaction was carried out as follows: the precursor solution was transferred to a 100 ml stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 140 °C for 6 h. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a dark green suspension. The dark green suspension was transferred to a centrifuge tube and centrifuged at 8000 rpm for 10 min, and the supernatant was discarded. The precipitate was washed 5 times each with deionized water and anhydrous ethanol. The washed precipitate was dried under vacuum at 50 °C for 8 h to obtain a layered CuS nanofunctional filler.

[0038] Step 3 Step 3.1: Prepare a composite emulsion of layered CuS nanofunctional filler and biomass aqueous polyurethane emulsion; Step 3.2: The composite emulsion is subjected to ultrasonic dispersion treatment. After ultrasonic treatment, the emulsion is subjected to vacuum defoaming and casting film treatment to obtain a biomass polyurethane substrate CuS photothermal composite film. Step 3.1 is as follows: Weigh 0.05 parts by weight of the prepared layered CuS nanofunctional filler and 20 parts by weight of the biomass aqueous polyurethane emulsion prepared in step one and add them to a container. Stir at room temperature for 60 min to obtain a composite emulsion. Step 3.2 is as follows: The composite emulsion is ultrasonicated for 40 min at a power of 200 W and a frequency of 40 kHz to obtain an ultrasonically dispersed emulsion. The ultrasonically dispersed emulsion is then uniformly cast into a horizontal polytetrafluoroethylene mold and allowed to stand for 20 min under a vacuum of -0.095 MPa to remove bubbles, resulting in a defoamed emulsion. The defoamed mold is then moved to a horizontal worktable and allowed to stand at room temperature for 2 days to obtain a biomass polyurethane substrate CuS photothermal composite film.

[0039] Example 5 This embodiment provides a method for preparing a biomass polyurethane substrate CuS photothermal composite film, specifically as follows: Step 1: Prepare a biomass-based aqueous polyurethane emulsion; Five parts by weight of polytrimethylene ether glycol, 4.5 parts by weight of isophorone diisocyanate, and 1 part by weight of dibutyltin dilaurate were weighed and added to a reaction vessel. The mixture was reacted at 80 °C for 2 h to obtain a polyurethane prepolymer. Then, 0.5 parts by weight of dimethylolpropionic acid was dissolved in 5 ml of N-methylpyrrolidone and added to the polyurethane prepolymer. The mixture was stirred continuously at 70 °C in an oil bath for 2 h. The temperature was further lowered to 40 °C, and then 2 parts by weight of triethylamine were added and reacted for 20 min to obtain a polyurethane prepolymer mixture neutralized by triethylamine. Separately, 1 part by weight of bone glue was dissolved in 50 parts by weight of water and stirred at 70 °C for 30 min. After complete dissolution, the temperature was lowered to 40 °C to obtain a bone glue aqueous solution. The bone glue aqueous solution was added to the above polyurethane prepolymer mixture neutralized by triethylamine and emulsified by high-speed shearing for 30 min to obtain a biomass aqueous polyurethane emulsion.

[0040] Step 2: Prepare layered CuS nano-functional fillers; First, a precursor solution is prepared. The precursor solution is subjected to a hydrothermal reaction to obtain a dark green suspension. After solid-liquid separation, washing, and drying, the dark green suspension is used to obtain a layered CuS nanofunctional filler. The precursor solution preparation steps are as follows: Weigh 1 part of polyvinylpyrrolidone and dissolve it in 50 ml of deionized water, and stir at 30 ℃ for 30 min; add 0.8 g of copper chloride dihydrate and 0.3 g of thiourea in sequence and continue stirring for 30 min; slowly add 1 part by weight of ammonia water, and stir at 30 ℃ for 2 h to obtain the precursor solution; The hydrothermal reaction was carried out as follows: the precursor solution was transferred to a 100 ml stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 160 °C for 4 h. After the reaction, the mixture was naturally cooled to room temperature to obtain a dark green suspension. The dark green suspension was transferred to a centrifuge tube and centrifuged at 8000 rpm for 15 min, and the supernatant was discarded. The precipitate was washed three times each with deionized water and anhydrous ethanol. The washed precipitate was dried under vacuum at 60 °C for 6 h to obtain a layered CuS nanofunctional filler.

[0041] Step 3 Step 3.1: Prepare a composite emulsion of layered CuS nanofunctional filler and biomass aqueous polyurethane emulsion; Step 3.2: The composite emulsion is subjected to ultrasonic dispersion treatment. After ultrasonic treatment, the emulsion is subjected to vacuum defoaming and casting film treatment to obtain a biomass polyurethane substrate CuS photothermal composite film. Step 3.1 is as follows: Weigh 0.1 parts by weight of the prepared layered CuS nanofunctional filler and 15 parts by weight of the biomass aqueous polyurethane emulsion prepared in step one and add them to a container. Stir at room temperature for 70 min to obtain a composite emulsion. Step 3.2 is as follows: The composite emulsion is ultrasonicated for 30 min at a power of 500 W and a frequency of 40 kHz to obtain an ultrasonically dispersed emulsion. The ultrasonically dispersed emulsion is then uniformly cast into a horizontal polytetrafluoroethylene mold and allowed to stand for 10 min under a vacuum of -0.1 MPa to remove bubbles, resulting in a defoamed emulsion. The defoamed mold is then moved to a horizontal worktable and allowed to stand at room temperature for 3 days to obtain a biomass polyurethane substrate CuS photothermal composite film.

[0042] Example 6 This embodiment provides a method for preparing a biomass polyurethane substrate CuS photothermal composite film, specifically as follows: Step 1: Prepare a biomass-based aqueous polyurethane emulsion; 4.2 parts by weight of polytrimethylene ether glycol, 4.7 parts by weight of isophorone diisocyanate, and 0.6 parts by weight of dibutyltin dilaurate were weighed and added to a reaction vessel. The mixture was reacted at 72 °C for 2.3 h to obtain a polyurethane prepolymer. Then, 0.6 parts by weight of dimethylolpropionic acid was dissolved in 3.5 ml of N-methylpyrrolidone and added to the polyurethane prepolymer. The mixture was stirred continuously in an oil bath at 63 °C for 2.1 h. The temperature was further lowered to 35 °C, and then 1.6 parts by weight of triethylamine was added and reacted for 23 min to obtain a polyurethane prepolymer mixture neutralized by triethylamine. Separately, 1.1 parts by weight of bone glue was dissolved in 42 parts by weight of water and stirred at 63 °C for 30 min. After complete dissolution, the temperature was lowered to 33 °C to obtain a bone glue aqueous solution. The bone glue aqueous solution was added to the above polyurethane prepolymer mixture neutralized by triethylamine and emulsified by high-speed shearing for 32 min to obtain a biomass aqueous polyurethane emulsion.

[0043] Step 2: Prepare layered CuS nano-functional fillers; First, a precursor solution is prepared. The precursor solution is subjected to a hydrothermal reaction to obtain a dark green suspension. After solid-liquid separation, washing, and drying, the dark green suspension is used to obtain a layered CuS nanofunctional filler. The precursor solution was prepared as follows: 0.6 parts of polyvinylpyrrolidone were weighed and dissolved in 55 ml of deionized water and stirred at 26 °C for 32 min; 0.65 g of copper chloride dihydrate and 0.32 g of thiourea were added sequentially and stirred for another 30 min; 1.5 parts by weight of ammonia water were slowly added dropwise and stirred at 26 °C for 2.2 h to obtain the precursor solution. The hydrothermal reaction was carried out as follows: the precursor solution was transferred to a 100 ml stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 145 °C for 4.5 h. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a dark green suspension. The dark green suspension was transferred to a centrifuge tube and centrifuged at 8000 rpm for 11 min, and the supernatant was discarded. The precipitate was washed three times each with deionized water and anhydrous ethanol. The washed precipitate was dried under vacuum at 52 °C for 6.5 h to obtain a layered CuS nanofunctional filler.

[0044] Step three specifically involves: Step 3.1: Prepare a composite emulsion of layered CuS nanofunctional filler and biomass aqueous polyurethane emulsion; Step 3.2: The composite emulsion is subjected to ultrasonic dispersion treatment. After ultrasonic treatment, the emulsion is subjected to vacuum defoaming and casting film treatment to obtain a biomass polyurethane substrate CuS photothermal composite film. Step 3.1 is as follows: Weigh 0.06 parts by weight of the prepared layered CuS nanofunctional filler and 16 parts by weight of the biomass aqueous polyurethane emulsion prepared in step one and add them to a container. Stir at room temperature for 62 min to obtain a composite emulsion. Step 3.2 is as follows: The composite emulsion is ultrasonicated for 32 min at a power of 250 W and a frequency of 40 kHz to obtain an ultrasonically dispersed emulsion. The ultrasonically dispersed emulsion is then uniformly cast into a horizontal polytetrafluoroethylene mold and allowed to stand for 12 min under a vacuum of -0.096 MPa to remove bubbles, resulting in a defoamed emulsion. The defoamed mold is then moved to a horizontal worktable and allowed to stand at room temperature for 2.2 days to obtain a biomass polyurethane substrate CuS photothermal composite film.

[0045] like Figure 1 As shown, the photothermal performance comparison curves of 0.5wt% layered CuS-bone glue-waterborne polyurethane (0.5wt% CuS-BG-WPU) and traditional bone glue-waterborne polyurethane (BG-WPU) are presented. The curves clearly demonstrate that the layered CuS nanoparticles endow the material with efficient photothermal conversion capabilities. Under standard solar irradiation, the material temperature rises rapidly and sharply. The photothermal response and temperature rise are far superior to the blank control group without copper sulfide composite, directly confirming the photothermal synergistic effect of layered CuS.

Claims

1. A method for preparing a biomass polyurethane substrate CuS photothermal composite film, characterized in that, Includes the following steps: Step 1: Prepare a biomass-based aqueous polyurethane emulsion; Step 2: Prepare layered CuS nano-functional fillers; Step 3: The layered CuS nano-functional filler obtained in Step 2 is mixed and stirred evenly with the biomass aqueous polyurethane emulsion obtained in Step 1. After ultrasonic dispersion, vacuum defoaming and casting film formation, the biomass polyurethane-based layered CuS photothermal composite film is obtained.

2. The method for preparing a biomass polyurethane substrate CuS photothermal composite film according to claim 1, characterized in that, Step one specifically involves: weighing 4-5 parts by weight of polytrimethylene ether glycol, 4.5-5 parts by weight of isophorone diisocyanate, and 0.5-1 parts by weight of dibutyltin dilaurate into a reaction vessel, and reacting at 70-80°C for 2-3 hours to obtain a polyurethane prepolymer; then dissolving 0.5-1 parts by weight of dimethylolpropionic acid in 3-5 ml of N-methylpyrrolidone, adding it to the polyurethane prepolymer, and continuously stirring at 60-70°C in an oil bath for 2-2.5 hours; further cooling to 40°C. Next, 1.5-2 parts by weight of triethylamine are added and reacted for 20-30 minutes to obtain a polyurethane prepolymer mixture neutralized by triethylamine; separately, 1-1.5 parts by weight of bone glue are dissolved in 40-50 parts by weight of water and stirred at 60-70°C for 30 minutes until completely dissolved, then cooled to 30-40°C to obtain a bone glue aqueous solution; the bone glue aqueous solution is added to the above-mentioned polyurethane prepolymer mixture neutralized by triethylamine and emulsified by high-speed shearing for 30-40 minutes to obtain the biomass aqueous polyurethane emulsion.

3. The method for preparing a biomass polyurethane substrate CuS photothermal composite film according to claim 2, characterized in that, Step two is as follows: First, weigh 0.5-1 part of polyvinylpyrrolidone and dissolve it in 50-80 ml of deionized water, and stir at 25-30℃ for 30-40 min; then add 0.6-0.8 g of copper chloride dihydrate and 0.3-0.4 g of thiourea sequentially and continue stirring for 30 min; slowly add 1-3 parts by weight of ammonia water, and stir at 25-30℃ for 2-3 h to obtain a precursor solution; transfer the precursor solution to a 100 ml stainless steel high-pressure reactor lined with polytetrafluoroethylene, and react at 140-160℃ for 4-6 h. After the reaction, allow it to cool naturally to room temperature to obtain a dark green suspension; transfer the dark green suspension to a centrifuge tube, centrifuge at 8000 rpm for 10-15 min and discard the supernatant; wash the precipitate alternately with deionized water and anhydrous ethanol 3-5 times each; dry the washed precipitate under vacuum at 50-60℃ for 6-8 h to obtain layered CuS nanofunctional filler.

4. The method for preparing a biomass polyurethane substrate CuS photothermal composite film according to claim 3, characterized in that, Step three specifically involves: Step 3.1: Weigh 0.05-0.1 parts by weight of the prepared layered CuS nanofunctional filler and 15-20 parts by weight of the biomass aqueous polyurethane emulsion prepared in step one and add them to a container. Stir at room temperature for 60-70 minutes to obtain a composite emulsion. Step 3.2: The composite emulsion is ultrasonicated for 30-40 minutes at a power of 200-500W and a frequency of 40kHz to obtain an ultrasonically dispersed emulsion. The ultrasonically dispersed emulsion is then uniformly cast into a horizontal polytetrafluoroethylene mold and allowed to stand for 10-20 minutes under a vacuum of -0.095MPa to -0.1MPa to remove bubbles, resulting in a defoamed emulsion. The defoamed mold is then transferred to a horizontal worktable and allowed to stand at room temperature for 2-3 days to obtain a biomass polyurethane substrate CuS photothermal composite film.

5. A biomass polyurethane substrate CuS photothermal composite film, prepared by the method described in claim 4.

6. The application of the biomass polyurethane substrate CuS photothermal composite film according to claim 5 in the fields of flexible photothermal conversion, biomass-based functional coatings and energy-saving and environmentally friendly functional materials.

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