Polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film, preparation method and application

Abstract

The invention discloses a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film as well as a preparation method and application thereof. The composite film comprises a polystyrene-maleic anhydride copolymer matrix and indium phosphide quantum dots, the indium phosphide quantum dots are uniformly distributed in the polystyrene-maleic anhydride copolymer matrix; the light transmittance of the composite film is greater than or equal to 90%; the tensile strength is greater than or equal to 232 MPa; the elongation is not less than 600%; the average stripping force is greater than or equal to 0.15 N. In the composite film, agglomeration of indium phosphide quantum dots in a film main body material such as an ethylene-vinyl acetate copolymer can be avoided, and the quantum dots are uniformly distributed in the composite film, so that the transmittance of the composite film is improved, the light conversion effect is optimized, and the display brightening effect is achieved.

Description

Technical Field

[0001] This invention relates to the field of organic-inorganic composite film materials and display and lighting devices. More specifically, it relates to a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film, its preparation method, and its applications. Background Technology

[0002] The technological development of display lighting devices has evolved from cold cathode fluorescent lamps to light-emitting diodes (LEDs), and then to miniature LEDs. Based on the arrangement of the light source, they are mainly divided into two structures: edge-lit and direct-lit. Edge-lit systems place the LED strips on the side of the light guide plate, using optical materials such as the light guide plate and diffuser sheets to convert the line light source into a uniform surface light source. Direct-lit systems arrange the LED array directly behind the panel; their optical structure is relatively simple and it is easy to achieve high brightness. However, existing backlight systems still generally face technical challenges such as insufficient light extraction efficiency and difficulty in ensuring brightness uniformity, which restricts further improvements in display performance.

[0003] To enhance the brightness and luminous efficacy of display lighting devices, the industry has developed various brightness enhancement technologies. At the optical design level, key methods include fabricating microstructures such as microprisms or V-grooves on the surface of the light guide plate to optimize light paths and reduce light loss, and employing multilayer optical films with higher light-gathering capabilities (such as brightness enhancement films (BEF) and polarization enhancement films (DBEF)) to recycle polarized light and improve front-side light extraction efficiency. Nevertheless, existing brightness enhancement solutions still present a trade-off between light energy utilization efficiency, manufacturing costs, and thinner designs, requiring further optimization.

[0004] Indium phosphide quantum dots (IPDs) are downconversion luminescent nanomaterials. Their application in brightness enhancement films represents a significant development in the display technology field, driven by the dual goals of high performance and environmental compliance. Their core value lies in using this environmentally friendly, cadmium-free nanomaterial to replace traditional cadmium-based quantum dots, achieving a wider color gamut and higher display brightness while meeting stringent environmental regulations. However, these inorganic luminescent nanomaterials are prone to agglomeration in the host materials of films such as organic resins, affecting the film's transmittance and overall light conversion efficiency. Summary of the Invention

[0005] The first technical problem to be solved by this invention is to provide a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film. In this composite film, the aggregation of indium phosphide quantum dots in the film substrate material, such as ethylene-vinyl acetate copolymer, is avoided, allowing the quantum dots to be uniformly distributed in the composite film, thereby improving the transmittance of the composite film, optimizing the light conversion effect, and achieving a brightening effect on the display.

[0006] The second technical problem to be solved by the present invention is to provide a method for preparing a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film.

[0007] The third technical problem to be solved by the present invention is to provide an application of a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film in enhancing the brightness of lighting devices.

[0008] To solve the first technical problem mentioned above, the invention adopts the following technical solution: A polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film comprises a polystyrene-maleic anhydride copolymer matrix and indium phosphide quantum dots; the indium phosphide quantum dots are uniformly distributed in the polystyrene-maleic anhydride copolymer matrix; the composite film has a light transmittance ≥90%; tensile strength ≥232 MPa; elongation ≥600%; and average peel force ≥0.15 N.

[0009] To solve the second technical problem mentioned above, the invention adopts the following technical solution: A method for preparing a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film includes the following steps: 1) Preparation of core-shell structured indium phosphide quantum dot solid powder by hot injection method: Indium precursor, ligand, and solvent are mixed, vacuumed, and heated to the nucleation reaction temperature. Then, phosphorus precursor is added, and the nucleation reaction is carried out in an inert environment to synthesize indium phosphide quantum dot cores. The temperature is then raised to the coating reaction temperature, and a dispersion or solution of the shell material is added to carry out the coating reaction. An antisolvent is added and centrifuged. The precipitate obtained after centrifugation is dried to obtain core-shell structured indium phosphide quantum dot solid powder. 2) Preparation of composites by enhanced mixing in a high-gravity reactor: The indium phosphide quantum dot solid powder and polystyrene-maleic anhydride copolymer obtained in step 1) are dispersed in the same volume of dispersant, and then simultaneously pumped into a preheated hypergravity reactor to obtain a dispersion of indium phosphide quantum dot composite modified with polystyrene-maleic anhydride copolymer. 3) Preparation of composite membrane masterbatch dispersion using a high-gravity rotating packed bed: The indium phosphide quantum dot composite dispersion obtained in step 2) and the ethylene-vinyl acetate copolymer solution were simultaneously pumped into a high-gravity reactor to obtain a composite membrane masterbatch dispersion. 4) Template method for film production: The composite membrane masterbatch dispersion obtained in step 3) is dropped into a mold and cured in an oven to form a film, thus obtaining a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite membrane.

[0010] Preferably, in step 1), the indium precursor is selected from one or more of indium chloride, indium bromide, indium iodide, indium acetate, and indium palmitate; the phosphorus precursor is selected from one or more of tridimethylaminophosphine and tritrimethylsilylphosphine; and the molar ratio of the indium precursor to the phosphorus precursor is 1:(4-10).

[0011] Preferably, in step 1), the ligand comprises at least one Z-ligand and one L-ligand; the Z-ligand is selected from one or more of zinc chloride, zinc bromide, zinc iodide, zinc acetate, zinc oleate, and zinc palmitate; the L-ligand is selected from one or more of oleylamine, hexadecylamine, oleic acid, palmitic acid, myristic acid, n-dodecyl mercaptan, octyl mercaptan, and tri-n-octylphosphine.

[0012] Preferably, in step 1), the solvent is selected from one or more of 1-octadecene, oleylamine, hexadecylamine, oleic acid, n-dodecyl mercaptan, octyl mercaptan, tri-n-octylphosphine, and liquid paraffin; the antisolvent is selected from one or more of acetone, ethanol, and methanol.

[0013] Preferably, in step 1), the shell material is selected from one or more of zinc chloride, zinc bromide, zinc iodide, selenium powder, sulfur powder, n-dodecyl mercaptan, zinc acetate, thiourea, zinc stearate, zinc oleate, and zinc acetate.

[0014] Preferably, in step 1), the dispersion or solution of the shell material is selected from one or more of 1-octadecene and tri-n-octylphosphine.

[0015] Preferably, in step 1), the nucleation reaction is carried out at a temperature of 180-250°C for 15-30 minutes; the coating reaction is carried out at a temperature of 250-350°C for 1-2 hours.

[0016] Preferably, in step 2), the dispersant is selected from one or more of n-hexane, chloroform, dichloromethane, toluene, tetrahydrofuran, and N,N-dimethylformamide.

[0017] Preferably, in step 2), the rotor speed of the supergravity reactor is 500-2500 rpm, the feed rate is 40-160 mL / min, and the temperature is 40-80℃.

[0018] Preferably, in step 2), the mass ratio of indium phosphide quantum dots to polystyrene-maleic anhydride copolymer is (3-45):250; and the concentration of indium phosphide quantum dots in the indium phosphide quantum dot composite dispersion is 0.16-2.4 mg / mL.

[0019] Preferably, in step 3), the rotor speed of the supergravity reactor is 500-2500 rpm, and the feed rate is 40-160 mL / min.

[0020] Preferably, in step 3), the mass ratio of the ethylene-vinyl acetate copolymer to the polystyrene-maleic anhydride copolymer is (5-10):1.

[0021] Preferably, in step 4), the mold is a 100 mm round glass petri dish or a 0.5 mm deep square polytetrafluoroethylene mold.

[0022] Preferably, in step 4), the curing temperature is 30-100℃ and the curing time is 10-30min.

[0023] To solve the third technical problem mentioned above, the invention adopts the following technical solution: Application of a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film in enhancing the brightness of lighting devices.

[0024] Any range described in this invention includes the endpoint, any value between the endpoints, and any subrange consisting of the endpoint or any value between the endpoints.

[0025] Unless otherwise specified, all raw materials used in this invention can be obtained commercially, and the equipment used in this invention can be conventional equipment in the relevant field or refer to existing technology in the relevant field.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1) This invention employs a high-gravity rotating packed bed to enhance the material mixing process. It utilizes the strong shear force of the high-gravity field to achieve atomic-level uniform mixing between reactants, thereby promoting the grafting modification effect of the copolymer on the surface of indium phosphide quantum dots.

[0028] 2) This invention uses polystyrene-maleic anhydride copolymer to modify the surface of indium phosphide quantum dots, so that they can be better blended and compounded with ethylene-vinyl acetate copolymer. This effectively avoids the aggregation of indium phosphide quantum dots in organic resin materials, enhances the overall application value of indium phosphide quantum dot-based composite films, and this strategy can also be extended to other organic resin film materials.

[0029] 3) The composite film prepared by this invention has a transmittance of ≥90%, tensile strength of ≥232 MPa, elongation of ≥600%, average peel force of ≥0.15 N, and has a good adhesion effect to the surface of display devices.

[0030] 4) The polystyrene-maleic anhydride copolymer in the composite film prepared by this invention can scatter and refract light within the film layer, extending the optical path and promoting the absorption of light by quantum dots. Furthermore, the quantum dots emit green light with a wavelength of 525 nm, which is brighter to the human eye compared to other wavelengths, thus achieving a brightening effect on lighting devices.

[0031] 5) The composite film prepared by this invention integrates encapsulation and light conversion functions. It is directly mixed with the main resin material of the film layer without increasing the number of film layers in the component, simplifying the preparation steps and reducing costs. Attached Figure Description

[0032] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Figure 1 This is a scanning electron microscope image of the composite membrane obtained in Example 1 of this invention; Figure 2 This is a partial scanning electron microscope image of the composite membrane obtained in Example 1 of this invention; Figure 3 This is the fluorescence emission spectrum of the composite film obtained in Example 1 of this invention; Figure 4 This is the fluorescence excitation spectrum of the composite film obtained in Example 1 of this invention; Figure 5 This is the transmittance curve of the composite membrane obtained in Example 1 of this invention; Figure 6 This is the tensile property curve of the composite membrane obtained in Example 1 of this invention; Figure 7 This is a scanning electron microscope image of the control membrane obtained in Comparative Example 1 of this invention; Figure 8 This is a scanning electron microscope image of the composite membrane obtained in Comparative Example 2 of this invention; Figure 9 These are images comparing the composite films obtained in Comparative Examples 1 and 2 of this invention with those in Example 1 when applied to light-emitting diodes; Figure 10 These are images comparing the composite films obtained in Comparative Examples 2 and 3 with those in Example 1. Figure 11 This is an optical image of the composite film obtained in Comparative Example 7 of this invention; Figure 12 This is an optical image of the composite film obtained in Comparative Example 8 of this invention. Detailed Implementation

[0033] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0034] For ease of description, the terms "first," "second," etc., used in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination should be considered non-existent and not within the scope of protection claimed by this invention.

[0035] As one aspect of the present invention, a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film is provided, comprising a polystyrene-maleic anhydride copolymer matrix and indium phosphide quantum dots; the indium phosphide quantum dots are uniformly distributed in the polystyrene-maleic anhydride copolymer matrix; the composite film has a light transmittance ≥90%; tensile strength ≥232 MPa; elongation ≥600%; and average peel force ≥0.15 N.

[0036] As another aspect of the present invention, a method for preparing a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film includes the following steps: 1) Preparation of core-shell structured indium phosphide quantum dot solid powder by hot injection method: Indium precursor, ligand, and solvent are mixed, vacuumed, and heated to the nucleation reaction temperature. Then, phosphorus precursor is added, and the nucleation reaction is carried out in an inert environment to synthesize indium phosphide quantum dot cores. The temperature is then raised to the coating reaction temperature, and a dispersion or solution of the shell material is added to carry out the coating reaction. An antisolvent is added and centrifuged. The precipitate obtained after centrifugation is dried to obtain core-shell structured indium phosphide quantum dot solid powder. 2) Preparation of composites by enhanced mixing in a high-gravity reactor: The indium phosphide quantum dot solid powder and polystyrene-maleic anhydride copolymer obtained in step 1) are dispersed in the same volume of dispersant, and then simultaneously pumped into a preheated hypergravity reactor to obtain a dispersion of indium phosphide quantum dot composite modified with polystyrene-maleic anhydride copolymer. 3) Preparation of composite membrane masterbatch dispersion using a high-gravity rotating packed bed: The indium phosphide quantum dot composite dispersion obtained in step 2) and the ethylene-vinyl acetate copolymer solution were simultaneously pumped into a high-gravity reactor to obtain a composite membrane masterbatch dispersion. 4) Template method for film production: The composite membrane masterbatch dispersion obtained in step 3) is dropped into a mold and cured in an oven to form a film, thus obtaining a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite membrane.

[0037] In some embodiments of the present invention, in step 1), the indium precursor is selected from one or more of indium chloride, indium bromide, indium iodide, indium acetate, and indium palmitate; the phosphorus precursor is selected from one or more of tridimethylaminophosphine and tritrimethylsilylphosphine; the molar ratio of the indium precursor to the phosphorus precursor is 1:(4-10), preferably 1:(5-7).

[0038] In some embodiments of the present invention, in step 1), the ligand comprises at least one Z-type ligand and one L-type ligand; the Z-type ligand is selected from one or more of zinc chloride, zinc bromide, zinc iodide, zinc acetate, zinc oleate, and zinc palmitate; the L-type ligand is selected from one or more of oleylamine, hexadecylamine, oleic acid, palmitic acid, myristic acid, n-dodecyl mercaptan, octyl mercaptan, and tri-n-octylphosphine.

[0039] In some embodiments of the present invention, in step 1), the solvent is selected from one or more of 1-octadecene, oleylamine, hexadecylamine, oleic acid, n-dodecyl mercaptan, octyl mercaptan, tri-n-octylphosphine, and liquid paraffin; the antisolvent is selected from one or more of acetone, ethanol, and methanol.

[0040] In some embodiments of the present invention, in step 1), the shell material is selected from one or more of zinc chloride, zinc bromide, zinc iodide, selenium powder, sulfur powder, n-dodecyl mercaptan, zinc acetate, thiourea, zinc stearate, zinc oleate, and zinc acetate.

[0041] In some embodiments of the present invention, in step 1), the dispersion or solution of the shell material is selected from one or more of 1-octadecene and tri-n-octylphosphine.

[0042] In some embodiments of the present invention, in step 1), the nucleation reaction is carried out at a temperature of 180-250°C for 15-30 min; the coating reaction is carried out at a temperature of 250-350°C for 1-2 h.

[0043] In some embodiments of the present invention, in step 2), the dispersant is selected from one or more of n-hexane, chloroform, dichloromethane, toluene, tetrahydrofuran, and N,N-dimethylformamide.

[0044] In some embodiments of the present invention, in step 2), the rotor speed of the hypergravity reactor is 500-2500 rpm; the feed rate is 40-160 mL / min, preferably 80-100 mL / min; and the temperature is 40-80℃.

[0045] In some embodiments of the present invention, in step 2), the mass ratio of indium phosphide quantum dots to polystyrene-maleic anhydride copolymer is (3-45):250; and the concentration of indium phosphide quantum dots in the indium phosphide quantum dot composite dispersion is 0.16-2.4 mg / mL.

[0046] In some embodiments of the present invention, in step 3), the rotor speed of the hypergravity reactor is 500-2500 rpm; the feed rate is 40-160 mL / min, preferably 80-100 mL / min.

[0047] In some embodiments of the present invention, in step 3), the mass ratio of the ethylene-vinyl acetate copolymer to the polystyrene-maleic anhydride copolymer is (5-10):1.

[0048] In some embodiments of the present invention, in step 4), the mold is a 100 mm circular glass petri dish or a 0.5 mm deep square polytetrafluoroethylene mold.

[0049] In some embodiments of the present invention, in step 4), the curing temperature is 30-100°C, preferably 50-70°C; and the curing time is 10-30 min.

[0050] As another aspect of the present invention, the present invention relates to the application of a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film in enhancing the brightness of lighting devices.

[0051] The indium phosphide quantum dots in the composite film emit 525 nm green light, which helps to improve the brightness perceived by the human eye. The polystyrene-maleic anhydride copolymer in the film layer can scatter and refract light, extend the light path, and promote the absorption of light by the quantum dots, thereby achieving the effect of enhancing the brightness of the lighting device. The principle behind the brightening effect of green light lies in the fact that green light (555 nm) has the largest photovisual function, maximizing the light intensity I and illuminance E perceived by the human eye. The formulas involved in this principle are shown below: Where Φ is the total light energy perceived by the human eye per unit time; For a light source at a specific wavelength The emitted radiation power is not considered in relation to human vision; is the photovisual function, dimensionless, representing the sensitivity of the ordinary eye to different wavelengths of light under normal (photovisual) illumination conditions (the peak value for green light at 555 nm is 1.0, and for other colors it is even lower); Km is the maximum luminous efficacy, with a value of 683 lm / W; I is the luminous intensity, i.e., the luminous flux of light emitted in a specific direction into a solid angle (light cone); is the size of the three-dimensional cone through which the light passes; E is the illuminance, i.e., the total luminous flux incident on a surface per unit area; A is the surface area receiving the light. Example 1

[0052] A method for preparing a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film, comprising the following steps: 1) Preparation of core-shell structured indium phosphide quantum dots by hot-injection method: Place 0.34 mmol indium iodide, 2.2 mmol zinc bromide, 5 mL oleylamine, and 5 mL 1-octadecene in a three-necked flask. Heat to 140°C and evacuate for 30 minutes, then purge the flask with... The mixture was heated to 200°C; 0.45 mL of tridimethylaminophosphine was rapidly injected and reacted for 20 minutes to obtain indium phosphide quantum dot cores; 1 mL of a mixed solution of selenium powder and sulfur powder (1.65 M, 1.1 mmol selenium powder and 2.2 mmol sulfur powder dissolved in 2 mL of tri-n-octylphosphine) and 10 mL of zinc precursor solution (1.5 g zinc stearate dissolved in 5 mL of 1-octadecene) were slowly added to the flask, and the mixture was reacted at 280°C for 120 minutes; 1.5 mL of n-dodecyl mercaptan was injected and the mixture was reacted at 300°C for 60 minutes; the mixture was cooled to room temperature, excess ethanol was added as an antisolvent, and the mixture was centrifuged twice at 10000 rpm; the resulting solid precipitate was dried at 60°C for six hours to obtain core-shell structured indium phosphide quantum dot solids; 2) Preparation of composites using hypergravity-enhanced hybridization: The indium phosphide quantum dot solid (12 mg) and 0.2 g polystyrene-maleic anhydride copolymer obtained in step 1) were dispersed in 15 mL of dichloromethane. The two materials were simultaneously pumped into a preheated high-gravity reactor (60 °C) at a feed rate of 80 mL / min for mixing. The rotor speed was 2000 rpm to obtain a dispersion of polystyrene-maleic anhydride copolymer-modified indium phosphide quantum dot composite. 3) Preparation of composite membrane masterbatch dispersion by centrifugal method: The composite dispersion obtained in step 2) and a 1 g dichloromethane solution of ethylene-vinyl acetate copolymer were simultaneously pumped into a high-gravity reactor at a rate of 80 mL / min and a rotor speed of 2000 rpm to obtain a masterbatch dispersion of the composite membrane. 4) Template method for film production: Pour the masterbatch dispersion obtained in step 3) into a 100 mm petri dish or a polytetrafluoroethylene mold, and cure it in an oven at 60°C for 30 minutes to form a film, thereby obtaining the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film.

[0053] Figure 1 This is a scanning electron microscope image of the composite membrane obtained in Example 1; Figure 2 This is a partial scanning electron microscope image of the composite membrane obtained in Example 1. Figure 3 This is the fluorescence emission spectrum of the composite film obtained in Example 1; Figure 4 This is the fluorescence excitation spectrum of the composite film obtained in Example 1; Figure 5 This is the transmittance curve of the composite membrane obtained in Example 1; Figure 6 This is the tensile property curve of the composite membrane obtained in Example 1. Example 2

[0054] Repeat Example 1, except that the rotor speed of the hypergravity reactor described in step 2) is 500 rpm.

[0055] Testing showed that the performance of the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film prepared in this embodiment was similar to that in Example 1. Example 3

[0056] Repeat Example 1, except that the rotor speed of the hypergravity reactor described in step 2) is 1000 rpm.

[0057] Testing showed that the performance of the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film prepared in this embodiment was similar to that in Example 1. Example 4

[0058] Repeat Example 1, except that the rotor speed of the hypergravity reactor described in step 2) is 1500 rpm.

[0059] Testing showed that the performance of the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film prepared in this embodiment was similar to that in Example 1. Example 5

[0060] Repeat Example 1, except that the rotor speed of the hypergravity reactor described in step 2) is 2500 rpm.

[0061] Testing showed that the performance of the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film prepared in this embodiment was similar to that in Example 1. Example 6

[0062] Repeat Example 1, except that the dispersant in step 2) is toluene.

[0063] Testing showed that the performance of the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film prepared in this embodiment was similar to that in Example 1. Example 7

[0064] Repeat Example 1, except that the solvent used in step 2) is chloroform.

[0065] Testing showed that the performance of the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film prepared in this embodiment was similar to that in Example 1. Example 8

[0066] Repeat Example 1, except that the solvent used in step 2) is tetrahydrofuran.

[0067] Testing showed that the performance of the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film prepared in this embodiment was similar to that in Example 1. Example 9

[0068] Repeat Example 1, except that the solvent used in step 2) is N,N-dimethylformamide.

[0069] Testing showed that the performance of the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film prepared in this embodiment was similar to that in Example 1.

[0070] Comparative Example 1 A method for preparing a pure ethylene-vinyl acetate copolymer film includes the following steps: Dissolve 1 g of ethylene-vinyl acetate copolymer in 5 mL of dichloromethane, then pour the solution into a polytetrafluoroethylene mold or petri dish, and cure it in a 60 °C oven for 30 minutes to allow the solvent to evaporate, thus obtaining a pure ethylene-vinyl acetate copolymer film.

[0071] Testing revealed that the film prepared in this comparative example was a transparent film with a transmittance of over 90%, but it had many large abnormal protrusions on its surface and did not show any brightening effect when applied to light-emitting diodes.

[0072] Figure 7 This is a scanning electron microscope image of the control membrane obtained in Comparative Example 1.

[0073] Comparative Example 2 (without copolymer modification) A method for preparing an indium phosphide quantum dot-based composite film includes the following steps: 1) Preparation of core-shell structured indium phosphide quantum dots by hot-injection method: Place 0.34 mmol indium iodide, 2.2 mmol zinc bromide, 5 mL oleylamine, and 5 mL 1-octadecene in a three-necked flask; heat to 140 °C and evacuate for 30 minutes, then purge the flask with... The mixture was heated to 200°C; 0.45 mL of tridimethylaminophosphine was rapidly injected and reacted for 20 minutes to obtain indium phosphide quantum dot cores; 1 mL of a mixed solution of selenium powder and sulfur powder (1.65 M, 1.1 mmol selenium powder and 2.2 mmol sulfur powder dissolved in 2 mL of tri-n-octylphosphine) and 10 mL of zinc precursor solution (1.5 g zinc stearate dissolved in 5 mL of 1-octadecene) were slowly added to the flask, and the mixture was reacted at 280°C for 120 minutes; 1.5 mL of n-dodecyl mercaptan was injected and the mixture was reacted at 300°C for 60 minutes. The mixture was cooled to room temperature, excess ethanol was added as an antisolvent, and the mixture was centrifuged twice at 10000 rpm. The resulting solid precipitate was dried at 60°C for six hours to obtain core-shell structured indium phosphide quantum dot solids. 2) Preparation of composite membrane masterbatch dispersion by centrifugal method: The quantum dot solid (12 mg) obtained in step 1) and 1 g of ethylene-vinyl acetate copolymer were added to 15 mL of dichloromethane and simultaneously pumped into a high-gravity rotating packed bed at a feed rate of 80 mL / min and a rotor speed of 2000 rpm to obtain a masterbatch dispersion of the composite membrane. 3) Template method for film production: The masterbatch dispersion obtained in step 2) is poured into a mold and cured in an oven at 60 ℃ for 30 minutes to form a film, thus obtaining the indium phosphide quantum dot-based composite film without polystyrene-maleic anhydride copolymer modification.

[0074] The difference between this comparative example and Example 1 is that step 2 of Example 1 is omitted, and the indium phosphide quantum dots obtained in step 1 are directly added to the ethylene-vinyl acetate copolymer to form a composite film masterbatch dispersion.

[0075] Testing revealed that, because the indium phosphide quantum dots in this comparative example were not surface-modified with polystyrene-maleic anhydride copolymer, the quantum dots were unevenly distributed in the composite film and partially agglomerated, affecting the overall luminescence performance of the film. The composite film surface was rough, with poor adhesion, failing to effectively bond to the device surface, and showed no incremental effect.

[0076] Figure 8 This is a scanning electron microscope image of the composite membrane obtained in Comparative Example 2; Figure 9 These are images comparing the application of the composite film obtained in Comparative Example 2 on a light-emitting diode with Comparative Example 1 and Example 1.

[0077] Comparative Example 3 ((Without using supergravity) A method for preparing a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film, comprising the following steps: 1) Preparation of core-shell structured indium phosphide quantum dots by hot-injection method: Place 0.34 mmol indium iodide, 2.2 mmol zinc bromide, 5 mL oleylamine, and 5 mL 1-octadecene in a three-necked flask. Heat to 140 °C and evacuate for 30 minutes, then purge the flask with... The mixture was heated to 200°C. 0.45 mL of tridimethylaminophosphine was rapidly injected and the reaction proceeded for 20 minutes to obtain indium phosphide quantum dot cores. A mixed solution of selenium and sulfur powder (1.65 M, 1.1 mmol selenium and 2.2 mmol sulfur dissolved in 2 mL tri-n-octylphosphine) and 10 mL of zinc precursor solution (1.5 g zinc stearate dissolved in 5 mL 1-octadecene) were slowly added to the flask, and the reaction proceeded at 280°C for 120 minutes. 1.5 mL of n-dodecyl mercaptan was injected and the reaction proceeded at 300°C for 60 minutes. The mixture was cooled to room temperature, excess ethanol was added as an antisolvent, and the mixture was centrifuged twice at 10000 rpm. The resulting solid precipitate was dried at 60°C for six hours to obtain core-shell structured indium phosphide quantum dot solids. 2) Preparation of composite membrane masterbatch dispersion by mixing in beakers: The quantum dot solid (12 mg), 1 g ethylene-vinyl acetate copolymer, and 0.2 g polystyrene-maleic anhydride copolymer obtained in step 1) were added to 45 mL of dichloromethane and stirred thoroughly to obtain a composite membrane masterbatch dispersion.

[0078] 3) Template method for film production: The masterbatch dispersion obtained in step 2) is poured into a mold and cured in an oven at 60 °C for 30 minutes to form a film, thus obtaining the indium phosphide quantum dot-based composite film without the use of supergravity-enhanced mixing.

[0079] Testing revealed that, because indium phosphide quantum dots and polystyrene-maleic anhydride copolymer were directly mixed in this comparative example without the use of a rotating packed bed, the solubility of the mixture was very poor. The quantum dots and polystyrene-maleic anhydride copolymer particles were unevenly distributed and severely agglomerated in the composite film, resulting in extremely low permeability and poor application performance.

[0080] Figure 10 These are images comparing the composite membrane obtained in Comparative Example 3 with those in Comparative Example 2 and Example 1.

[0081] Comparative Example 4 Repeat Example 1, except that the ligand described in step 1) is only zinc bromide and contains oleylamine.

[0082] Testing revealed that, because the comparative example contained only zinc bromide (Z-type ligand) and no oleylamine (L-type ligand), the indium sites on the surface of the indium phosphide quantum dots could be passivated by zinc bromide, while the phosphorus sites lacked passivation by the L-type ligand, resulting in extremely high surface energy. Ultimately, this led to a high defect density in the synthesized indium phosphide quantum dots, thus preventing them from emitting fluorescence.

[0083] In principle, this is because Z-type ligands (such as zinc bromide) are electron pair acceptors. Zinc ions tend to coordinate with indium sites on the surface of indium phosphide quantum dots, and the positively charged indium ions can accept electron pairs from the ligand anions (bromine ions) to form indium-bromine bonds. L-type ligands (such as oleylamine) are Lewis bases and are electron pair donors. Their lone pair electrons can coordinate to the phosphorus sites on the surface of indium phosphide quantum dots, thereby saturating the dangling bonds of phosphorus. The lack of oleylamine would result in the complete exposure of the phosphorus sites, which would not be passivated. These unpassivated phosphorus sites possess extremely high surface energies, driving surface atomic reconstruction and forming intrinsic defects such as phosphorus-phosphorus dimers and phosphorus vacancies. These surface defects introduce deep-level trap states into the indium phosphide bandgap, becoming powerful nonradiative recombination centers. This causes photogenerated carriers to dissipate through a heat-generating pathway, resulting in complete quenching of quantum dot fluorescence. Furthermore, oleylamine plays a crucial kinetic regulatory role in the synthesis of indium phosphide quantum dots. As a surfactant and dynamic ligand, it dominates the stable formation of monodisperse nuclei and the controllable growth process through Ostwald ripening. More importantly, the amine passivated surface it forms is the ideal chemical interface for subsequent low-defect epitaxial shell growth. Therefore, the absence of oleylamine will undermine the entire thermodynamic and kinetic foundation from nucleation to the construction of a complete core-shell structure.

[0084] Comparative Example 5 Repeat Comparative Example 1, except that the antisolvent used in step 1) is water.

[0085] Testing revealed that, because water, as an antisolvent, in this comparative example, would damage the microstructure of indium phosphide quantum dots, the addition of a large amount of water would cause the quantum dots to aggregate and settle, adhering to the centrifuge tube wall, and the fluorescence intensity would be significantly weakened.

[0086] Comparative Example 6 Repeat Comparative Example 1, except that the dispersant for zinc stearate in step 1) is n-hexane.

[0087] Testing revealed that, due to the poor dispersion of zinc stearate in hexane in this comparative example, large zinc stearate particles would clog the needle when the dispersion was taken with a syringe. The use of hexane would further affect the dispersion and dissolution of zinc stearate in the reaction solution, forming lumpy solids that would prevent it from effectively coating the surface of indium phosphide quantum dots.

[0088] Comparative Example 7 Repeat Comparative Example 1, except that the indium phosphide quantum dot solid described in step 2) is 100 mg.

[0089] Testing revealed that the excessive solid content of indium phosphide quantum dots in this comparative example, with a mass ratio of 1:2 to polystyrene-maleic anhydride copolymer, resulted in the obvious color and severe agglomeration of the indium phosphide quantum dots, leading to extremely poor permeability and poor application performance of the composite film.

[0090] Figure 11 This is an optical image of the composite film obtained in Comparative Example 7.

[0091] Comparative Example 8 Repeat Comparative Example 1, except that the mass of the polystyrene-maleic anhydride copolymer in step 2) is 1g.

[0092] Testing revealed that the excessive content of polystyrene-maleic anhydride copolymer in this comparative example, with a mass ratio of 1:1 to ethylene-vinyl acetate copolymer, resulted in severe copolymer particle agglomeration in the composite membrane, significantly impacting its transmittance. Furthermore, the copolymer also caused the aggregation and quenching of indium phosphide quantum dots, leading to a lack of significant fluorescence in the composite membrane and affecting its light conversion efficiency.

[0093] Figure 12 This is an optical image of the composite film obtained in Comparative Example 8.

[0094] In summary, the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film prepared by this invention has high transmittance and uniform distribution of indium phosphide quantum dots; the composite film has strong adhesion and tensile properties, indicating that the composite film obtained by this invention can meet the application requirements of light conversion film and achieve the effect of brightening the display.

[0095] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film, characterized in that: The composite film comprises a polystyrene-maleic anhydride copolymer matrix and indium phosphide quantum dots; the indium phosphide quantum dots are uniformly distributed in the polystyrene-maleic anhydride copolymer matrix; the composite film has a light transmittance ≥90%; tensile strength ≥232 MPa; elongation ≥600%; and average peel force ≥0.15 N.

2. The method for preparing the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film as described in claim 1, characterized in that, Includes the following steps: 1) Preparation of core-shell structured indium phosphide quantum dot solid powder by hot injection method: Indium precursor, ligand, and solvent are mixed, vacuumed, and heated to the nucleation reaction temperature. Then, phosphorus precursor is added, and the nucleation reaction is carried out in an inert environment to synthesize indium phosphide quantum dot cores. The temperature is then raised to the coating reaction temperature, and a dispersion or solution of the shell material is added to carry out the coating reaction. An antisolvent is added and centrifuged. The precipitate obtained after centrifugation is dried to obtain core-shell structured indium phosphide quantum dot solid powder. 2) Preparation of composites by enhanced mixing in a high-gravity reactor: The indium phosphide quantum dot solid powder and polystyrene-maleic anhydride copolymer obtained in step 1) are dispersed in the same volume of dispersant, and then simultaneously pumped into a preheated hypergravity reactor to obtain a dispersion of indium phosphide quantum dot composite modified with polystyrene-maleic anhydride copolymer. 3) Preparation of composite membrane masterbatch dispersion using a high-gravity rotating packed bed: The indium phosphide quantum dot composite dispersion obtained in step 2) and the ethylene-vinyl acetate copolymer solution were simultaneously pumped into a high-gravity reactor to obtain a composite membrane masterbatch dispersion. 4) Template method for film production: The composite membrane masterbatch dispersion obtained in step 3) is dropped into a mold and cured in an oven to form a film, thus obtaining a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite membrane.

3. The method for preparing the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film according to claim 2, characterized in that: In step 1), the indium precursor is selected from one or more of indium chloride, indium bromide, indium iodide, indium acetate, and indium palmitate; the phosphorus precursor is selected from one or more of tridimethylaminophosphine and tritrimethylsilylphosphine; and the molar ratio of the indium precursor to the phosphorus precursor is 1:(4-10).

4. The method for preparing the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film according to claim 2, characterized in that: In step 1), the ligand includes at least one Z-type ligand and one L-type ligand; the Z-type ligand is selected from one or more of zinc chloride, zinc bromide, zinc iodide, zinc acetate, zinc oleate, and zinc palmitate; the L-type ligand is selected from one or more of oleylamine, hexadecylamine, oleic acid, palmitic acid, myristic acid, n-dodecyl mercaptan, octyl mercaptan, and tri-n-octylphosphine.

5. The method for preparing the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film according to claim 2, characterized in that: In step 1), the solvent is selected from one or more of 1-octadecene, oleylamine, hexadecylamine, oleic acid, n-dodecyl mercaptan, octyl mercaptan, tri-n-octylphosphine, and liquid paraffin; the antisolvent is selected from one or more of acetone, ethanol, and methanol.

6. The method for preparing the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film according to claim 2, characterized in that: In step 1), the shell material is selected from one or more of zinc chloride, zinc bromide, zinc iodide, selenium powder, sulfur powder, n-dodecyl mercaptan, zinc acetate, thiourea, zinc stearate, zinc oleate, and zinc acetate.

7. The method for preparing the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film according to claim 2, characterized in that: In step 1), the dispersion or solution of the shell material is selected from one or more of 1-octadecene and tri-n-octylphosphine.

8. The method for preparing the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film according to claim 2, characterized in that: In step 1), the nucleation reaction is carried out at a temperature of 180-250℃ for 15-30 min; the coating reaction is carried out at a temperature of 250-350℃ for 1-2 h.

9. The method for preparing the polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film according to claim 2, characterized in that: In step 2), the dispersant is selected from one or more of n-hexane, chloroform, dichloromethane, toluene, tetrahydrofuran, and N,N-dimethylformamide; Preferably, in step 2), the rotor speed of the supergravity reactor is 500-2500 rpm, the feed rate is 40-160 mL / min, and the temperature is 40-80℃. Preferably, in step 2), the mass ratio of indium phosphide quantum dots to polystyrene-maleic anhydride copolymer is (3-45):250; the concentration of indium phosphide quantum dots in the indium phosphide quantum dot composite dispersion is 0.16-2.4 mg / mL; Preferably, in step 3), the rotor speed of the centrifugal reactor is 500-2500 rpm, and the feed rate is 40-160 mL / min; Preferably, in step 3), the mass ratio of the ethylene-vinyl acetate copolymer to the polystyrene-maleic anhydride copolymer is (5-10):1; Preferably, in step 4), the mold is a 100 mm round glass petri dish or a 0.5 mm deep square polytetrafluoroethylene mold. Preferably, in step 4), the curing temperature is 30-100℃ and the curing time is 10-30min.

10. Application of a polystyrene-maleic anhydride copolymer-based indium phosphide quantum dot composite film in enhancing the brightness of lighting devices.

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