A light-converting agent, a method for preparing the light-converting agent, and a light-converting film.

Abstract

This application discloses a light-converting agent, a method for preparing the light-converting agent, and a light-converting film. The light-converting film in this application is a europium complex copolymer synthesized by free radical copolymerization of an Eu complex and a Rhodamine B derivative. The Eu complex has a double bond structure exposed outside the 5-amino-1,10-phenanthroline molecule, and the exposed double bond position of the Eu complex structure is connected by a substitution reaction between an amino group and an acryloyl chloride. The Rhodamine B derivative has an exposed double bond structure attached to the carboxyl group of Rhodamine B. The method for preparing the light-converting agent in this application sequentially involves synthesizing 5-acrylamido-1,10-phenanthroline, synthesizing the Eu complex, synthesizing the Rhodamine B derivative, and synthesizing the light-converting agent. The light-converting film in this application includes the light-converting agent. The light-converting agent and the light-converting film in this application can convert both ultraviolet and yellow-green light into red light, improving the utilization rate of sunlight in plant photosynthesis.

Description

Technical Field

[0001] This application relates to the field of agricultural light-converting film technology, and in particular to a light-converting agent, a method for preparing the light-converting agent, and a light-converting film. Background Technology

[0002] With the rapid growth of the world's population, and given the current level of productivity, light-converting films are commonly used in agriculture to protect plants and increase crop yields in order to meet the enormous demand for food. Light-converting films are functional agricultural films that improve light utilization efficiency by using light-converting agents to enhance light transmittance and convert light wavelengths. Existing light-converting agents typically only convert a portion of the ultraviolet light in sunlight into the blue-violet or red-orange light required by plants. In the total energy of the incident solar spectrum, ultraviolet radiation accounts for less than 4%, while visible light accounts for over 50%, with yellow-green light being particularly prominent. Current technologies lack light-converting agents that can fully convert yellow-green light into red light, resulting in low utilization of sunlight in plant production and limited effectiveness of using light-converting films to increase crop yields in agriculture.

[0003] Furthermore, in practical applications of light-conversion films, the poor compatibility between the light-converting agent and the polymer substrate leads to low mechanical properties, poor dispersibility (easily forming ion clusters, causing concentration quenching), and high mobility, ultimately resulting in a decrease in the luminescent performance of the film and a significant reduction in its lifespan. Moreover, existing light-conversion films commonly use either polyethylene, which is difficult to degrade and causes environmental pollution, or carboxymethyl cellulose, which is easily soluble in water, causing "white pollution" and an excessively short lifespan. Summary of the Invention

[0004] In view of the deficiencies in the prior art, this application provides a light-converting agent, a method for preparing the light-converting agent, and a light-converting film to solve the technical problems in the prior art, such as the inability of the light-converting film to effectively utilize the yellow-green light in sunlight, the poor compatibility between the light-converting agent and the polymer substrate in the light-converting film, and the low performance of the existing light-converting film.

[0005] To achieve the objectives of the above application, the technical solution provided in this application is as follows:

[0006] A light-converting agent for use in a light-converting film, wherein the light-converting agent is a europium complex copolymer synthesized by free radical copolymerization of an Eu complex and a rhodamine B derivative, wherein the Eu complex has a double bond structure exposed outside the 5-amino-1,10-phenanthroline molecule, and the exposed double bond position of the Eu complex structure is connected by an amino group and an acryloyl chloride through a substitution reaction; the rhodamine B derivative has a double bond structure exposed outside the molecule connected at the carboxyl group position of rhodamine B, and the rhodamine B derivative is prepared by a substitution reaction of rhodamine B and allyl bromide.

[0007] In one embodiment, the general molecular formula of the Eu complex is Eu(TTA)3(Aphen), wherein TTA is 2-thiophenecarboxyltrifluoroacetone and Aphen is 5-acrylamido-1,10-phenanthroline.

[0008] In one embodiment, the structural formula of the light-converting agent is:

[0009]

[0010] Its elemental analysis data are: C, 54.53; H, 4.29; N, 4.37; O, 10.11; S, 6.14; Eu, 9.62; its gel permeation chromatography analysis showed that the polydispersity index Mw / Mn was 1.23, where Mw is the weight-average molecular weight and Mn is the number-average molecular weight.

[0011] In one embodiment, the number-average molecular weight of the light-converting agent is 6000-6800 (Mn), the molar ratio of the Eu complex to the Rhodamine B derivative in the light-converting agent is 1:1, and the degree of polymerization (n) of the light-converting agent is 4.

[0012] This application also provides a method for preparing the above-mentioned light-converting agent, comprising the following steps:

[0013] S1. Synthesis of 5-acrylamido-1,10-phenanthroline;

[0014] S2. Europium chloride hexahydrate was dissolved in distilled water to form a europium chloride solution. The europium chloride solution was heated to a certain temperature, and 2-thiophenecarboxyltrifluoroacetone, 5-acrylamido-1,10-phenanthroline synthesized in S1, and anhydrous ethanol solution were added to the europium chloride solution. The temperature of the mixture was maintained and stirred uniformly at this temperature for a period of time to allow the precipitate to precipitate completely. The precipitate was washed and filtered with distilled water and anhydrous ethanol solution, and dried in a vacuum oven at a certain temperature for a period of time to synthesize the Eu complex.

[0015] S3. Add Rhodamine B to a container, then add N,N-dimethylformamide, bromopropylene and cesium carbonate to the container in sequence. Stir at a certain temperature for a period of time. After the reaction in the container is completed, concentrate the filtrate. Dissolve the concentrated filtrate in dichloromethane to filter cesium carbonate. Dissolve the filtrate in a small amount of methanol. After shaking, pour the solution into diethyl ether to precipitate the product. Separate the product by decantation and dry it in a vacuum drying oven at a certain temperature to synthesize the Rhodamine B derivative.

[0016] S4. The mixture of Rhodamine B derivative synthesized in step S3, Eu complex synthesized in step S2, and azobisisobutyronitrile is dissolved in a dried tetrahydrofuran solution in a container to form a ligand solution. The ligand solution is purged with argon gas for a period of time and sealed under a reducing argon atmosphere. The ligand solution is continuously stirred at a certain temperature for a period of time to copolymerize. After the reaction is completed, the viscous solution is diluted with a certain amount of tetrahydrofuran solution and precipitated into a certain amount of methanol under vigorous stirring. The resulting copolymer product is filtered, collected, and dried under reduced pressure. The copolymer product is purified and vacuum dried for a period of time to synthesize the light-converting agent.

[0017] In one embodiment, step S1 specifically includes: stirring and mixing a suspension of acetonitrile containing 5-amino-1,10-phenanthroline under room temperature and an argon atmosphere; sequentially adding triethylamine, acryloyl chloride, and acetonitrile reagents to the suspension; allowing the suspension to react for a period of time; concentrating the suspension under reduced pressure to obtain a residue; performing chromatographic separation on the residue using an eluent made of chloroform and ethanol to remove the solvent from the residue; and synthesizing 5-acrylamido-1,10-phenanthroline.

[0018] In one embodiment, in step S4, the ligand solution comprises the following components: 9 mM of Rhodamine B derivative and 9 mM of Eu complex; 0.5 wt% of azobisisobutyronitrile; 40 ml of over-dried tetrahydrofuran solution solvent; and 50 ml of methanol.

[0019] This embodiment provides a light-converting film, comprising the above-mentioned light-converting agent and a polymer matrix.

[0020] In one embodiment, the polymer matrix is ​​polylactic acid.

[0021] Compared with the prior art, this application has at least the following beneficial effects:

[0022] In this application, the light-converting agent is a europium complex copolymer synthesized by free radical copolymerization of an Eu complex and a Rhodamine B derivative. The Eu complex has a double bond structure exposed outside the 5-amino-1,10-phenanthroline molecule, and the Rhodamine B derivative has a double bond structure exposed outside the molecule at the carboxyl group of Rhodamine B. In this copolymer, the Eu complex partially retains the ultraviolet absorption and red light emission capabilities of the organoraven-earth complex, while the Rhodamine B derivative can transfer the energy of the yellow-green light portion to the luminescent guest of the organoraven-earth complex, thereby converting the yellow-green light into red light. Therefore, the light-converting agent and light-converting film in this application can not only convert ultraviolet light into red light, but also convert the strong yellow-green light in the visible light into red light, improving the utilization rate of sunlight in the plant photosynthetic process.

[0023] The light-converting agent in this application has good compatibility with the polymer matrix, resulting in a light-converting film with better luminescence performance, stability, and mechanical properties. The lifespan of the light-converting film in this application is longer than that of existing light-converting films. The polymer matrix of the light-converting film in this application is polylactic acid (PLA), which is an environmentally friendly material that is insoluble in water, thus reducing environmental pollution while ensuring the performance of the light-converting film. Attached Figure Description

[0024] Figure 1 This is a roadmap for the chemical synthesis of light-converting agents from Eu complexes and Rhodamine B derivatives;

[0025] Figure 2 These are actual images of different light-converting agents;

[0026] Figure 3 This is the optimal excitation and emission pattern of the light-converting agent in this application;

[0027] Figure 4 This is the emission pattern of the light-converting agent in the ultraviolet region in this application;

[0028] Figure 5 These are actual images of different light-converting films;

[0029] Figure 6 This is a comparison chart of the ultraviolet absorption of different light conversion films;

[0030] Figure 7 These are comparison images of the transmission of different light conversion films;

[0031] Figure 8 This is the optimal excitation and emission pattern of the light transfer film in this application;

[0032] Figure 9 This is the emission pattern of the light transfer film in the ultraviolet region in this application;

[0033] Figure 10 This is the emission pattern of the light transfer film in the visible light region of this application;

[0034] Figure 11 This is a comparison diagram of the conversion effects of different light-converting films on xenon lamp light sources;

[0035] Figure 12 This is a comparison diagram of the conversion effects of different light-converting films on the solar spectrum;

[0036] Figure 13 This is a comparison chart of the mobility of different light conversion films;

[0037] Figure 14 This is a stability test diagram of the light transfer film in this application;

[0038] Figure 15 This is a stability test chart of the PLA-A light conversion film;

[0039] Figure 16 This is a stability test chart of the PLA-C light conversion film;

[0040] Figure 17 These are comparison images of the surfaces (abc) and cross-sections (def) of different light-converting films;

[0041] Figure 18 This is a comparison table of the mechanical properties of different light-converting films;

[0042] Figure 19 These are comparison images showing the planting effects of using different light-converting films to grow lettuce;

[0043] Figure 20 This is a comparison chart showing the growth rate of lettuce grown using different light-converting films, with a 20cm scale as a reference.

[0044] Figure 21 This is a line graph showing the effect of different light-converting films on the growth rate of lettuce;

[0045] Figure 22(a) is a comparison of the effects of different light-converting films on the wet weight of lettuce;

[0046] Figure 22(b) is a comparison of the effects of different light-converting films on the dry weight of lettuce;

[0047] Figure 22(c) is a comparison of the effects of different light-converting films on the number and width of lettuce leaves;

[0048] Figure 22(d) is a comparison of the effects of different light-converting films on lettuce plant height and root length;

[0049] Figure 22(e) is a comparison of the effects of different light-converting films on the soluble sugar content of lettuce;

[0050] Figure 22(f) is a comparison of the effects of different light-converting films on the soluble protein content of lettuce; Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this application clearer, the application is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of this application. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0052] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0053] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be construed as indicating or implying relative importance. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0054] In the description of this application, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical connection or internal connection between two components. They can be direct connection or indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0055] To better understand the technical solution of this application, the application will be described in detail below with reference to the accompanying drawings.

[0056] A light-converting agent for a light-converting film is a europium complex copolymer synthesized by free radical copolymerization of an Eu complex and a rhodamine B derivative. The Eu complex has a double bond structure exposed outside the 5-amino-1,10-phenanthroline molecule, with the exposed double bond position of the Eu complex structure connected by a substitution reaction between an amino group and an acryloyl chloride. The rhodamine B derivative has a double bond structure exposed outside the molecule at the carboxyl group position of rhodamine B, and is prepared by a substitution reaction between rhodamine B and allyl bromide. The general molecular formula of the Eu complex is Eu(TTA)3(Aphen), where TTA is 2-thiophenecarboxyltrifluoroacetone and Aphen is 5-acrylamido-1,10-phenanthroline. The chemical synthesis of the Eu complex and the rhodamine B derivative is as follows: Figure 1 As shown. In this application, the Eu complex containing a double bond structure is abbreviated as LCA-A, the Rhodamine B derivative is abbreviated as RB-D, and the light conversion agent is abbreviated as P. Eu .

[0057] The structural formula of the light-converting agent is:

[0058]

[0059] Its elemental analysis data is Anal.Found.for P EuC, 54.53; H, 4.29; N, 4.37; O, 10.11; S, 6.14; Eu, 9.62. Gel permeation chromatography (GPC) analysis of the light-transfer agent yielded a polydispersity index (Mw / Mn) of 1.23, where Mw is the weight-average molecular weight and Mn is the number-average molecular weight. The number-average molecular weight of Mn is 6000-6800, and in this example, Mn is 6200. The molar ratio of the Eu complex to the Rhodamine B derivative in the light-transfer agent is 1:1, and the degree of polymerization (n) of the light-transfer agent is 4.

[0060] This application introduces a rhodamine B derivative with yellow-green light absorption capability into an organoravenous earth complex to form a europium complex luminescent copolymer. In this copolymer, the organoravenous earth complex partially retains its ultraviolet absorption and red light emission (λ). em =615nm; 5 D0- 7 F2) Capability. Organo-rare earth complexes and rhodamine B derivatives partially construct suitable guest-host systems, achieving efficient intramolecular energy transfer through polymer formation. In this system, the rhodamine B derivative acts as a receiving antenna for yellow-green light energy and serves as an effective energy donor and hole transport material to transfer the yellow-green light portion of the energy to the luminescent guest of the organo-rare earth complex, thereby achieving the conversion of yellow-green light into red light.

[0061] The present invention also provides a method for preparing the above-mentioned light-converting agent, comprising the following steps:

[0062] S1. Synthesis of 5-acrylamido-1,10-phenanthroline.

[0063] A suspension of acetonitrile containing 5-amino-1,10-phenanthroline (Mr: 195.22) (0.98 g, 5.0 mmol) was stirred and mixed at room temperature and under an argon atmosphere. The acetonitrile suspension consisted of 20 mL of acetonitrile. 2 mL of triethylamine, 1.5 mL of acryloyl chloride, and 15 mL of acetonitrile reagent were added dropwise to the suspension. After the suspension was allowed to react for 24 hours, the suspension was concentrated under reduced pressure to obtain a residue. The residue was then subjected to chromatographic separation on a silica gel column using an eluent prepared from chloroform and ethanol to remove the solvent, yielding 0.72 g of yellow crystals containing 5-acrylamido-1,10-phenanthroline.

[0064] The volume ratio of chloroform to ethanol in the eluent was 9:1. In this application, 5-acrylamido-1,10-phenanthroline is referred to as AMP. The yield of AMP was 73.2%.

[0065] The AMP high-resolution mass spectrometry (HRMS) data synthesized in this step are: calcd for [C 15 H 11 [N3O]249.0900; found [M+H] + 250.0000. The 1H NMR data are as follows: δ 9.27 (tt, J = 7.4, 3.7 Hz, 2H), 8.46–8.38 (m, 1H), 8.27 (dd, J = 8.1, 1.8 Hz, 1H), 8.11 (dd, J = 8.3, 1.7 Hz, 1H), 7.78–7.66 (m, 2H), 7.56 (s, 1H), 6.65–6.50 (m, 2H), 5.79 (dd, J = 8.6, 3.3 Hz, 1H).

[0066] S2, Synthesize Eu complexes.

[0067] 0.18 g of 0.5 mM europium chloride hexahydrate (EuCl3·6H2O) was placed in a 50 ml round-bottom flask and dissolved in 20 ml of distilled water. The EuCl3 solution was heated to 60 °C on a magnetic stirrer. 0.33 g of 1.5 mM TTA and 0.12 g of 0.5 mM AMP in anhydrous ethanol were added to the EuCl3 solution. The mixture was then stirred uniformly at 60 °C for 3 hours to allow complete precipitation. The precipitate was washed and filtered with distilled water and anhydrous ethanol and dried in a vacuum oven at 60 °C for 12 hours to obtain 0.52 g of a pale yellow solid powder, which was the Eu complex.

[0068] The pale yellow solid powder contained 81.3% LCA-A by mass. The high-resolution mass spectrometry (HRMS) data for LCA-A synthesized in this step are: calcd for [C 39 H 23 EuF9N3O7S3]1064.7600; found[M-5H] 5- 1059.8626. The organic elemental analysis result is Anal.Calcd.forC. 39 H 23EuF9N3O7S3: C, 43.99; H, 2.18; N, 3.95; O, 10.52; S, 9.03; Eu, 14.27; found: C, 43.88;

[0069] S3. Synthesize Rhodamine B derivatives.

[0070] Under a nitrogen atmosphere at room temperature, 0.96 g of 2 mM Rhodamine B was added to a 100 ml round-bottom flask. Then, 20 ml of N,N-dimethylformamide, 1.33 g of bromopropylene, and 0.65 g of cesium carbonate were added sequentially to the round-bottom flask. The mixture was stirred at 80 °C for 48 hours. After the reaction was completed, the filtrate was concentrated. The concentrated filtrate was dissolved in dichloromethane to filter out the cesium carbonate. The filtrate was dissolved in a small amount of methanol, shaken, and the solution was poured into diethyl ether to precipitate the product. The product was separated by decantation and dried in a vacuum drying oven at 60 °C to synthesize 0.81 g of Rhodamine B derivative.

[0071] The yield of the rhodamine B derivative obtained in this step was 84.5%. The high-resolution mass spectrometry (HRMS) data of the RB-D synthesized in this step are: calcd for [C 31 H 35 N2O3] + 483.2600; found [M] + 483.2644. The organic elemental analysis result is Anal.Calcd.for C. 31 H 35 N2O3: C, 76.99; H, 7.29; N, 5.79; O, 9.92; found: C, 76.96; H, 7.3; N, 5.82; O, 9.87.

[0072] S4, Synthetic light-converting agent.

[0073] A mixture of 0.43 g of 9 mM rhodamine B derivative, 0.96 g of Eu(TTA)3 (Aphen), and 0.007 g of azobisisobutyronitrile (AIBN) solid was dissolved in 40 mL of dry tetrahydrofuran (THF) solvent in a glass polymerization tube to form a ligand solution. The solution was purged with argon for 5 minutes to homogenize it, and then sealed under a reducing argon atmosphere. The ligand solution was continuously stirred at 60 °C for 72 hours to copolymerize. After the reaction was complete, the viscous solution was diluted with 5 mL of THF, and the precipitate was added to 50 mL of methanol under vigorous stirring. The obtained solid material was collected by filtration and dried under reduced pressure to obtain the copolymer product. The copolymer product was further purified by Soxhlet extraction with boiling acetone for 48 hours. Finally, the copolymer product was dried in a vacuum oven at 40 °C for 24 hours to synthesize 0.85 g of europium polymer, which is the color-converting agent.

[0074] The AIBN solid used accounted for 0.5% by weight, and the yield of the light-converting agent obtained in this step was 61.2%. Elemental analysis data for the light-converting agent synthesized in this step are available from Anal.Found.for P. Eu C, 54.53; H, 4.29; N, 4.37; O, 10.11; S, 6.14; Eu, 9.62. Gel permeation chromatography (GPC) analysis of the light-transfer agent yielded a polydispersity index (Mw / Mn) of 1.23, where Mw is the weight-average molecular weight and Mn is the number-average molecular weight, with Mn ranging from 6000 to 6800. The molar ratio of the Eu complex to the Rhodamine B derivative in the light-transfer agent was 1:1, and the degree of polymerization (n) of the light-transfer agent was 4.

[0075] This invention also provides a light-converting film, comprising the aforementioned light-converting agent and a polymer matrix, wherein the polymer matrix in this embodiment is polylactic acid. The light-converting film containing the light-converting agent of this application can specifically absorb energy in both ultraviolet and yellow-green light bands, thereby maximizing the increase of red light components in the plant spectrum. Its effect in plant cultivation experiments is superior to traditional light-converting films that only absorb ultraviolet light. The polymer matrix of this application is polylactic acid, an environmentally friendly material that is insoluble in water. This solves the technical problems of existing light-converting films with polyethylene as the matrix being difficult to degrade and polluting the environment, as well as the technical problems of light-converting films with carboxymethyl cellulose as the matrix being easily soluble in water and having a short service life.

[0076] The light-converting agent of this invention achieves free radical copolymerization through a double bond structure (Eu complex and rhodamine B derivative) exposed on the outside of two molecules, linking the two ligands to form a polymer structure. The connection of two molecules to the same polymer chain facilitates more efficient [polymerization / polymerization]. It utilizes the energy of yellow-green light through dexter energy transfer. Furthermore, the polymer structure exhibits excellent compatibility with the polymer substrate, which solves the serious defect problem caused by poor compatibility between the light-converting agent and the polymer substrate in existing technologies.

[0077] The following sections describe the existing light-converting agents, namely the conventional europium complex LCA-C, the light-converting agent LCA-A containing a double-bond Eu complex, and the light-converting agent P obtained in this application by free radical copolymerization of the Eu complex (LCA-A) and the rhodamine B derivative (RB-D). Eu Make a comparison to illustrate P Eu It can convert ultraviolet and yellow-green light into red light.

[0078] like Figure 2 As shown, the luminescence of different light-converting agents under different illuminations reveals that LCA-C, LCA-A, and P... Eu All three light-converting agents can emit red light under ultraviolet light irradiation at a wavelength of 365nm, indicating that they can convert ultraviolet light into red light needed for plant growth; LCA-C, LCA-A, and P Eu Both emitted blue light under 450nm blue light irradiation, indicating that none of the three light-converting agents could convert to blue light; LCA-C and LCA-A emitted orange light under 600nm orange light irradiation, indicating that neither of the two light-converting agents could convert to orange light; P Eu Under 600nm orange light illumination, they emit red light, indicating that the light-converting agent can convert to orange light; under 525nm green light illumination, LCA-C and LCA-A emit green light, P Eu The emission of red light indicates that neither LCA-C nor LCA-A can convert to green light. Eu It can convert green light into red light needed by plants; similarly, under 580nm yellow light illumination, LCA-C and LCA-A emit yellow light, P Eu The emission of red light indicates that neither LCA-C nor LCA-A can convert to yellow light. Eu It can convert yellow light into red light that plants need.

[0079] Figure 3 P was displayed Eu The optimal excitation state is: when excited by yellow-green light with a wavelength of 567nm, it can emit orange-red light with a wavelength of 603nm. Figure 4 P was displayed Eu It can also emit 615nm red light when excited by ultraviolet light. Figure 3 and Figure 4 This proves P again. Eu It can convert ultraviolet and yellow-green light into red light.

[0080] The following examples illustrate a light-converting film made entirely of polylactic acid (hereinafter referred to as PLA), a light-converting film made of polylactic acid and a conventional europium complex (hereinafter referred to as PLA-C), a light-converting film made of polylactic acid and an Eu complex containing a double bond structure (hereinafter referred to as PLA-A), and a light-converting film made of polylactic acid and the light-converting agent of this application (hereinafter referred to as PLA-P). Eu (Using alternatives) as a comparison to illustrate PLA-P Eu It can convert ultraviolet and yellow-green light into red light.

[0081] The preparation processes for different membranes are as follows: Take four 20g portions of polylactic acid solid, and dissolve each portion of polylactic acid solid in 80ml of dichloromethane to form polylactic acid solutions. Add 5wt% of LCA-C, LCA-A, and P to three of the polylactic acid solutions, respectively. Eu The three mixed solutions and the polylactic acid solution were poured into a fully automatic coating machine (model XD-TM-320, purchased from Beijing Xingde Precision Instruments Co., Ltd.) for coating (parameters set as follows: speed 20 cm / min, temperature 50℃, coating thickness 100 μm) to obtain polylactic acid films PLA, PLA-C, PLA-A, and PLA-P. Eu .

[0082] Figure 5 The images in the image are labeled PLA, PLA-C, PLA-A, and PLA-P from left to right. Eu， The luminescence of different light-converting films under different illuminations shows that PLA-C, PLA-A, and PLA-P Eu All three types of light-converting films emit red light under ultraviolet light irradiation at a wavelength of 365nm, indicating that they can convert ultraviolet light into red light needed for plant growth; PLA, PLA-C, PLA-A, and PLA-P Eu All four films emitted blue light under 450nm blue light illumination, indicating that none of them could convert blue light. PLA, PLA-C, and PLA-A all emitted orange light under 600nm orange light illumination, indicating that none of these three films could convert orange light. PLA-P Eu The film emits weak red light under 600nm orange light illumination, indicating that it can convert some orange light and is a non-major conversion region. Under 525nm green light illumination, PLA, PLA-C, and PLA-A emit green light, while PLA- emits red light, indicating that PLA, PLA-C, and PLA-A cannot convert green light, and PLA-P... Eu It can convert green light into red light needed by plants; similarly, under 580nm yellow light irradiation, only PLA-P... Eu The red light indicates that only PLA-P Eu It can convert yellow light into red light that plants need.

[0083] from Figure 6 and Figure 7 It can be seen that PLA-P Eu Like PLA-C and PLA-A, it exhibits significant absorption of ultraviolet light. Figure 8 Display PLA-P Eu The optimal excitation state is: when excited by yellow-green light with a wavelength of 572 nm, it can emit red light with a wavelength of 624 nm. Figure 9 PLA-P was displayed Eu It can also emit 613nm red light when excited by ultraviolet light. Figure 8 and Figure 9 This proves once again that PLA-P Eu It can convert ultraviolet and yellow-green light into red light. Figure 10 PLA-P was displayed Eu It can emit 624nm red light under visible light irradiation in the wavelength range of 400-610nm, and especially under yellow-green light irradiation, it can emit high-intensity 624nm red light. Figure 11 In the ultraviolet light with a wavelength of 300-400nm, PLA-P Eu The emission intensity of both PLA-C and PLA-A decreased, indicating that PLA-P Eu Like PLA-C and PLA-A, it can absorb ultraviolet light, but only PLA-P absorbs ultraviolet light in the wavelength range of 500-600nm, i.e., yellow-green light. Eu The decrease in emission intensity indicates that only PLA-P Eu It can absorb yellow-green light, and in the wavelength of 600-700nm, i.e., red light, PLA-P Eu The increased strength of both PLA-C and PLA-A indicates that PLA-P Eu Both PLA-C and PLA-A can convert ultraviolet light into red light, but PLA-P... Eu It can also convert yellow-green light into red light. PLA-C and PLA-A exhibit a sharp intensity peak at 600-700nm, indicating that the full width at half maximum (FWHM) of traditional light-converting films is too narrow, resulting in poor matching with the absorption spectrum of plant photosynthesis. PLA-P, on the other hand... Eu The red light emission peak has a large full width at half maximum (FWHM), therefore the light conversion film in this application improves the matching degree between its conversion spectrum and the absorption spectrum of plant photosynthesis. Figure 12 It can be seen that PLA-P Eu The conversion effect of PLA-C and PLA-A on the solar spectrum is the same as that under a xenon lamp, indicating that PLA-P Eu In practical applications, it is expected to achieve the same results as indoor experiments.

[0084] from Figure 13 It can be seen that PLA-PEu The mobility curve of PLA is close to that of PLA, and PLA-P Eu The slope of the PLA-P migration curve is much smaller than that of the PLA-C and PLA-A migration curves, indicating that PLA-P Eu The mobility is close to that of PLA with no mobility, and PLA-P Eu Its migration rate is much smaller than that of PLA-C and PLA-A. Figure 17 In the diagram, a) and d) represent the surface and cross-section of PLA-C, respectively; b) and e) represent the surface and cross-section of PLA-A, respectively; and c) and f) represent the surface and cross-section of PLA-P, respectively. Eu The surface and cross-section. From Figure 13 and 17 It can be seen that PLA-P Eu Its compatibility is far superior to that of PLA-C and PLA-A. (By...) Figure 14-16 The comparison shows that PLA-P Eu Its ability to retain luminescent properties is far superior to PLA-C and PLA-A; therefore, PLA-P Eu It has strong luminescence stability, PLA-P Eu Its service life is longer than that of PLA-C and PLA-A. From Figure 18 It can be seen that PLA-P Eu Its mechanical properties are superior to PLA-C and PLA-A, and even slightly better than those of PLA.

[0085] Lettuce is often chosen as a model plant due to its popularity in hydroponic production systems. Indoor lettuce mulching experiments can directly demonstrate the role of light-converting films in plant production. Below, PLA, PLA-C, PLA-A, and PLA-P are used. Eu The relevant physiological indicators of lettuce after being coated were compared.

[0086] from Figure 19-21 It can be seen that PLA-P Eu Compared to PLA, PLA-C, and PLA-A, which all significantly promote the growth and development of lettuce, PLA-P... Eu The lettuce grown under mulch exhibits higher leaf density and plant height. The plant height of the lettuce after mulching was tracked at 2-day intervals to reflect the growth rate of the lettuce. Figure 20 and Figure 21 As shown, the results indicate that the PLA-P Eu Over the next eight days, the plant height of PLA-P was significantly higher than that of PLA, PLA-C, and PLA-A. On the eighth day, PLA-P... Eu The lettuce plant height in the film-covered treatment groups was 1.32, 1.14, and 1.13 times that of the PLA, PLA-C, and PLA-A treatment groups, respectively.Eu It can effectively promote the growth rate of lettuce, thanks to PLA-P Eu Provides more red light for the growth and development of lettuce.

[0087] Measuring the biomass and nutritional quality of lettuce samples is a direct method to verify the effect of light conversion membranes on lettuce growth. Therefore, we measured relevant physiological indicators of lettuce 20 days after film covering. The results showed that... Figure 22a As shown, compared to PLA, PLA-P Eu PLA-C and PLA-A significantly increased the fresh weight of lettuce above ground by 72.22%, 39.58%, and 40.97% (p<0.05), respectively, and the fresh weight of lettuce below ground by 94.12%, 67.65%, and 70.59%, respectively. The effect of mulching on the dry weight of lettuce was similar to that on the fresh weight, increasing the dry weight of lettuce above ground by 76.88%, 42.59%, and 44.11%, respectively, and the dry weight of lettuce below ground by 108.79%, 75.23%, and 80.65%, respectively. Figure 22b As shown. Furthermore, in terms of plant height (22.76%, 11.22%, and 14.39%), root length (37.00%, 13.22%, and 15.99%)... Figure 22d As shown), leaf number (73.56%, 43.84%, and 46.16%) and leaf width (21.33%, 10.27%, and 11.73%) Figure 22c In terms of physiological indicators such as (as shown), PLA-P Eu The performance of PLA-P was significantly better than other membrane treatments. Soluble sugar and soluble protein content are important indicators of the nutritional quality of lettuce. Test results showed that, compared with PLA, PLA-P... Eu The soluble sugar content of lettuce in the PLA-C and PLA-A membrane treatment groups ( Figure 22e The percentages of soluble protein (as shown) increased by 43.91%, 23.65%, and 25.90% respectively (p<0.05), and the soluble protein content (... Figure 22f As shown, the improvements were 59.38%, 35.42%, and 40.77%, respectively (p<0.05). Clearly, the europium complex copolymer film PLA-P... Eu It significantly increased the content of soluble sugars and soluble proteins in lettuce.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them; although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation methods of the application or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of this application, and all of them should be covered within the scope of the technical solutions claimed in this application.

Claims

1. A light-converting agent for use in a light-converting film, characterized in that, The light-converting agent is a europium complex copolymer synthesized by free radical copolymerization of Eu complex and rhodamine B derivative. The Eu complex has a double bond structure exposed outside the 5-amino-1,10-phenanthroline molecule, and the exposed double bond position of the Eu complex structure is connected by an amino group and acryloyl chloride through a substitution reaction. The structure of the rhodamine B derivative is that an exposed double bond structure is connected at the carboxyl position of rhodamine B, and the rhodamine B derivative is prepared by a substitution reaction of rhodamine B and bromopropene.

2. The light-converting agent as described in claim 1, characterized in that, The general molecular formula of the Eu complex is Eu(TTA)3(Aphen), where TTA is 2-thiophenecarboxyltrifluoroacetone and Aphen is 5-acrylamido-1,10-phenanthroline.

3. The light-converting agent as described in claim 1, characterized in that, The structural formula of the light-converting agent is: ， Its elemental analysis data are: C, 54.53; H, 4.29; N, 4.37; O, 10.11; S, 6.14; Eu, 9.62; its gel permeation chromatography analysis showed a polydispersity index Mw / Mn of 1.23, where Mw is the weight-average molecular weight and Mn is the number-average molecular weight.

4. The light-converting agent as described in claim 3, characterized in that, The number-average molecular weight Mn of the light-converting agent is 6000-6800, the molar ratio of the Eu complex to the Rhodamine B derivative in the light-converting agent is 1:1, and the degree of polymerization n of the light-converting agent is 4.

5. A method for preparing the light-converting agent as described in claim 1, characterized in that, Includes the following steps: S1. Synthesis of 5-acrylamido-1,10-phenanthroline; S2. Europium chloride hexahydrate was dissolved in distilled water to form a europium chloride solution. The europium chloride solution was heated to a certain temperature, and 2-thiophenecarboxyltrifluoroacetone, 5-acrylamido-1,10-phenanthroline synthesized in S1, and anhydrous ethanol solution were added to the europium chloride solution. The temperature of the mixture was maintained and stirred uniformly at this temperature for a period of time to allow the precipitate to precipitate completely. The precipitate was washed and filtered with distilled water and anhydrous ethanol solution, and dried in a vacuum oven to synthesize the Eu complex. S3. Add Rhodamine B to a container, then add N,N-dimethylformamide, bromopropylene and cesium carbonate in sequence. Stir at a certain temperature for a period of time. After the reaction in the container is completed, concentrate the filtrate. Dissolve the concentrated filtrate in dichloromethane to filter cesium carbonate. Dissolve the filtrate in a small amount of methanol. After shaking, pour the solution into diethyl ether to precipitate the product. Separate the product by decantation and dry it in a vacuum drying oven at a certain temperature to synthesize the Rhodamine B derivative. S4. The mixture of Rhodamine B derivative synthesized in step S3, Eu complex synthesized in step S2, and azobisisobutyronitrile is dissolved in a container containing dried tetrahydrofuran solvent to form a ligand solution. The ligand solution is purged with argon gas for a period of time and sealed under a reducing argon atmosphere. The ligand solution is continuously stirred at a certain temperature for a period of time to copolymerize. After the reaction is completed, the viscous solution is diluted with a certain amount of tetrahydrofuran solution and precipitated into a certain amount of methanol under vigorous stirring. The resulting solid material is filtered, collected, and dried under reduced pressure. The copolymer product is purified and vacuum dried sequentially for a period of time to synthesize the light-converting agent.

6. The method for preparing the light-converting agent as described in claim 5, characterized in that, Step S1 specifically includes: stirring and mixing a suspension of acetonitrile containing 5-amino-1,10-phenanthroline under room temperature and argon atmosphere; adding triethylamine, acryloyl chloride and acetonitrile reagent dropwise to the suspension in sequence; allowing the suspension to react for a period of time; concentrating the suspension under reduced pressure to obtain a residue; performing chromatographic separation on the residue using an eluent made of chloroform and ethanol to remove the solvent from the residue; and synthesizing 5-acrylamido-1,10-phenanthroline.

7. The method for preparing the light-converting agent as described in claim 5, characterized in that, In step S4, the components of the ligand solution are as follows: 9 mM of Rhodamine B derivative and 9 mM of Eu complex; 0.5 wt% of azobisisobutyronitrile; 40 ml of over-dried tetrahydrofuran solvent; and 50 ml of methanol.

8. A light-converting film, characterized in that, Includes the light-converting agent and polymer matrix as described in any one of claims 1-4.

9. The light-converting film as described in claim 8, characterized in that, The polymer matrix is ​​polylactic acid.

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