Light conversion microsphere with adjustable emission wavelength and high quantum yield, preparation method and application

Abstract

The invention discloses a light conversion microsphere with adjustable emission wavelength and high quantum yield, a preparation method and application. Maleic anhydride copolymer microspheres are prepared through a self-stabilization precipitation polymerization method; the invention relates to a light conversion microsphere with adjustable emission wavelength and high quantum yield. A maleic anhydride copolymer microsphere is subjected to amine treatment to prepare an aminated polymer microsphere. And inducing intramolecular cyclization of the microspheres through simple heat treatment to obtain the maleimide-based polymer microspheres with adjustable emission wavelength. And finally, blending the prepared microspheres with a polymer matrix to prepare the light conversion film. The light conversion microspheres have the advantages of high luminous efficiency, adjustable luminous wavelength and the like, and the prepared polymer composite film can convert harmful ultraviolet rays into blue light or red light beneficial to plant growth and development and is used in the field of agricultural light conversion films; the material can also be compounded to the surface of a solar cell, optimizes the solar spectrum, and converts high-energy ultraviolet rays into effective wave bands absorbed by the solar cell, thereby improving the energy conversion efficiency of the solar cell.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying light-converting microspheres with tunable emission wavelength and high quantum yield, belonging to the field of functional polymer materials technology. Background Technology

[0002] Organic light-emitting materials (OLEDs) possess unique optical properties and are the cornerstone of high-tech fields including display lighting, bioimaging, and optoelectronic devices. In recent years, traditional OLEDs based on valence conjugation have become increasingly important in our daily lives. Their extensive π-electronic structure endows them with high emission efficiency and tunable emission colors. However, these materials typically exhibit aggregation-induced quenching in aggregated or solid-state environments, a phenomenon characterized by significant fluorescence at high concentrations or in the solid state. Furthermore, complex synthesis processes, poor processability, insufficient stability, and biotoxicity severely hinder the practical application of traditional OLEDs.

[0003] Cluster-emissive polymers have attracted widespread attention as a novel class of fluorescent materials. They lack traditional valence-bonded conjugated structures and are composed of electron-rich heteroatoms (N, P, O, S) with lone pairs of electrons or isolated unsaturated bonds (C=O, C≡N, C=N, S=O). In their aggregated or solid-state states, the lone pairs or π electrons in these structures form spatial conjugations, expanding the delocalization of electrons and simultaneously making the conformation rigid. The aggregation of these subunits can form clusters, generating luminescence through intramolecular and intermolecular spatial interactions, exhibiting unique cluster emission characteristics. These unconventional fluorescent polymers possess advantages such as simple synthesis, tunable emission wavelength, low biotoxicity, and good water solubility, showing broad application prospects in bioimaging and agricultural light-converting film materials.

[0004] Currently, cluster-luminescent polymers still suffer from problems such as blue light emission, low fluorescence quantum yield, poor stability, and poor processability. Therefore, a light-converting microsphere with tunable emission wavelength and high quantum yield has been proposed. Studying the atypical fluorescence mechanism and applications of this microsphere has significant theoretical and practical value. Summary of the Invention

[0005] To address the problems of single emission wavelength, low luminescence intensity, low quantum yield, and poor thermal stability in existing non-conjugated cluster luminescent polymers, this invention provides a light-converting microsphere with tunable emission wavelength and high quantum yield, along with its applications. First, maleic anhydride copolymer microspheres are prepared via a simple and efficient self-stabilizing precipitation polymerization method. After the reaction, the microspheres are purified by centrifugation or filtration. Then, the maleic anhydride microspheres are added to a round-bottom flask and reacted with an amine. After vacuum drying, amination polymer microspheres are obtained. Finally, the amination microspheres are heated in a tube furnace to induce intramolecular cyclization, yielding maleimide polymer microspheres. This method is simple, economical, efficient, and suitable for industrial production.

[0006] The technical solution of the present invention:

[0007] On the one hand, a light-converting microsphere is provided, which converts between ultraviolet light and blue or red light, that is, it absorbs ultraviolet light of 300-400nm, the amination polymer microsphere can emit blue light of 440-550nm, and the maleimide polymer microsphere can emit red light with a maximum wavelength of 650nm.

[0008] A method for preparing light-converting microspheres with tunable emission wavelength and high quantum yield, characterized in that the preparation method includes the following steps:

[0009] (1) Maleic anhydride, vinyl monomer and initiator are added to solvent, ultrasonically dissolved and mixed evenly to obtain reaction system. The reaction is carried out in the reaction system under inert gas protection. After the reaction, centrifugation is used to purify and dry to obtain maleic anhydride copolymer microspheres.

[0010] (2) The maleic anhydride copolymer microspheres described in step (1) are reacted with amines and dried under vacuum to obtain amination polymer microspheres; then, the amination polymer microspheres are heated under inert gas protection to cause intramolecular cyclization to obtain maleimide polymer microspheres; the amination polymer microspheres and maleimide polymer microspheres are collectively referred to as light conversion microspheres;

[0011] The amine is ammonia, methylamine, or ethylamine.

[0012] The structure of the vinyl monomer is shown in Formula I below:

[0013]

[0014] Formula I, wherein R is a saturated alkyl group; preferably a straight-chain alkane with a linear structure.

[0015] Further, in step (1), the solvent is one or a mixture of two or more of the following: butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, benzyl acetate, phenyl acetate, ethyl butyrate, isoamyl butyrate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate, ethyl phenylacetate, propyl phenylacetate, butyl phenylacetate, and isoamyl phenylacetate; the initiator is one of azobisisobutyronitrile, benzoyl peroxide, and potassium persulfate, more preferably azobisisobutyronitrile.

[0016] Furthermore, the vinyl monomer is vinyl acetate.

[0017] Further, in step (1), the concentrations of maleic anhydride and vinyl monomers in the reaction system are 0.2-1.0 mol / L, the initiator is 0.5-4 wt% of the total monomer content, the reaction temperature is 70℃-90℃, and the reaction time is 5-8 h; in step (2), the heating temperature is 140℃-180℃, and the heating time is 6-12 h. More preferably, it is 170℃, so as to promote the amination of polymer microspheres to complete acylation after heat treatment for 12 h.

[0018] Furthermore, in step (2), the amine treatment not only expands the emission wavelength range of the amination polymer microspheres to 350-550 nm, but also increases the quantum yield of the amination polymer microspheres to 45.24%.

[0019] Furthermore, in step (2), after the amination polymer microspheres are heated, the maximum emission wavelength of the prepared maleimide-based polymer microspheres is red-shifted to 550-650 nm, and the quantum yield is increased to 5%-9%.

[0020] A light-converting microsphere with tunable emission wavelength and high quantum yield, wherein the light-converting microsphere is an amination polymer microsphere or a maleimide polymer microsphere prepared by the above-described preparation method, wherein the amination polymer microsphere is shown in Formula II and the maleimide polymer microsphere is shown in Formula III.

[0021] Formula II Formula III In the formula, n is a positive integer.

[0022] An application of a light-converting microsphere with tunable emission wavelength and high quantum yield is specifically as follows: the light-converting microsphere is mixed with a polymer matrix to prepare a transparent light-converting composite material that emits blue or red light, wherein the light-converting microsphere comprises 1 to 2 parts per 100 parts by weight of the polymer matrix.

[0023] Furthermore, the polymer matrix is ​​one or more of polyvinyl alcohol, polyurethane, polyethylene, polypropylene, polyvinyl chloride, and polyoxyethylene.

[0024] Furthermore, the light conversion composite material is applied in the fields of agricultural light conversion film and solar photovoltaic cell light conversion film.

[0025] The beneficial effects of this invention are:

[0026] 1. In the preparation method described in this invention, the cluster-luminescent polymer in step (1) exhibits good photostability and reactivity. In step (2), the amination polymer particles prepared by amine treatment can achieve a quantum yield of up to 45.24% at an excitation wavelength of 350 nm. Then, through simple heat treatment to induce intramolecular cyclization of the amination microspheres, the aggregation state and electronic interactions of the carbonyl clusters are altered, forming cluster luminescent centers with narrower energy levels, resulting in maleimide polymer microspheres with a significantly red-shifted emission wavelength.

[0027] 2. Compared to traditional methods for improving the fluorescence properties of cluster-luminescent polymers, this invention does not require complex chemical modification, has a simple synthesis procedure, and is suitable for large-scale production. The cluster-luminescent polymer microspheres prepared by this invention have the characteristics of tunable emission wavelength, high quantum yield, good thermal stability, and environmental friendliness.

[0028] 3. The light-converting microspheres prepared by the present invention can be blended with a polymer matrix to prepare an agricultural light-converting film with good compatibility and dispersibility. This film can efficiently convert harmful ultraviolet rays into strong blue or red light that is conducive to plant growth and development. Attached Figure Description

[0029] Figure 1 The images show the 3D fluorescence spectrum and scanning electron microscope image of the maleic anhydride copolymer in Comparative Example 1.

[0030] Figure 2 The images show the 3D fluorescence spectrum and scanning electron microscope images of the cluster-luminescent polymer in Example 1.

[0031] Figure 3 The images show the 3D fluorescence spectrum and scanning electron microscope images of the cluster-luminescent polymer in Example 2.

[0032] Figure 4 The images show the 3D fluorescence spectrum and scanning electron microscope image of the cluster-luminescent polymer in Example 5.

[0033] Figure 5 The image shows the 3D fluorescence spectrum of the composite film prepared by melt blending the cluster-luminescent polymer and PE in Example 1.

[0034] Figure 6 This is a photograph of the composite film prepared by melt blending the cluster-luminescent polymer with PE in Example 1.

[0035] Figure 7The image shows the 3D fluorescence spectrum of the composite film prepared by melt blending the cluster-luminescent polymer with PE in Example 5.

[0036] Figure 8 This is a photograph of the composite film prepared by melt blending the cluster-luminescent polymer with PE in Example 5. Detailed Implementation

[0037] Examples of the contents included in the claims

[0038] Comparative Example 1:

[0039] Preparation of maleic anhydride copolymer microspheres: 2.45 g maleic anhydride, 2.30 mL vinyl acetate, and 0.035 g azobisisobutyronitrile (AIBN) were added to a 250 mL three-necked flask, followed by 25 mL n-butyl acetate. After sonication to dissolve the microspheres, the mixture was connected to the reaction vessel. Nitrogen gas was purged through the reaction system for 30 min, and then the three-necked flask was placed in a 70 °C oil bath for 7 h under nitrogen protection throughout the reaction. After the reaction was complete, the product was centrifuged at 10000 r / min for 5 min. The supernatant was discarded, and the solid was washed three times with petroleum ether. The centrifuged product was then dried in a 50 °C vacuum oven to constant weight.

[0040] Example 1:

[0041] (1) Preparation of maleic anhydride copolymer microspheres: 2.45 g maleic anhydride, 2.30 mL vinyl acetate and 0.035 g azobisisobutyronitrile were added to a 250 mL three-necked flask, followed by 25 mL n-butyl acetate. After ultrasonic dissolution, the mixture was connected to the reaction vessel. Nitrogen gas was purged through the reaction system for 30 min, and then the three-necked flask was placed in a 70 °C oil bath for 7 h of reaction under nitrogen protection throughout. After the reaction was completed, the product was centrifuged at 10000 r / min for 5 min. The supernatant was discarded, and the solid was washed three times with petroleum ether. The centrifuged product was then dried in a 50 °C vacuum oven to constant weight.

[0042] (2) Preparation of cluster luminescent polymer: 0.5g of maleic anhydride copolymer microspheres were added to a 50 mL round-bottom flask, and then excess ammonia was introduced to react with the microspheres to prepare amination polymer microspheres, which were denoted as cluster luminescent polymer 1.

[0043] The structure of the amination polymer microspheres in this embodiment is as follows:

[0044]

[0045] Example 2:

[0046] (1) Preparation of maleic anhydride copolymer microspheres: 2.45 g maleic anhydride, 2.30 mL vinyl acetate and 0.035 g azobisisobutyronitrile were added to a 250 mL three-necked flask, followed by 25 mL n-butyl acetate. After ultrasonic dissolution, the mixture was connected to the reaction vessel. Nitrogen gas was purged through the reaction system for 30 min, and then the three-necked flask was placed in a 70 °C oil bath for 7 h of reaction under nitrogen protection throughout. After the reaction was completed, the product was centrifuged at 10000 r / min for 5 min. The supernatant was discarded, and the solid was washed three times with petroleum ether. The centrifuged product was then dried in a 50 °C vacuum oven to constant weight.

[0047] (2) Preparation of cluster-luminescent polymer: 0.5 g of maleic anhydride copolymer microspheres were added to a 50 mL round-bottom flask, and excess ammonia gas was introduced to react with the microspheres to prepare amination polymer microspheres. The amination polymer microspheres were placed in a tube furnace and heated at 140 °C under nitrogen protection for 12 h to obtain maleimide polymer microspheres, which were denoted as cluster-luminescent polymer 2.

[0048] The structures of the cluster-luminescent polymers in Examples 2-6 are as follows:

[0049]

[0050] Example 3:

[0051] (1) Preparation of maleic anhydride copolymer microspheres: 2.45 g maleic anhydride, 2.30 mL vinyl acetate and 0.035 g azobisisobutyronitrile were added to a 250 mL three-necked flask, followed by 25 mL n-butyl acetate. After ultrasonic dissolution, the mixture was connected to the reaction vessel. Nitrogen gas was purged through the reaction system for 30 min, and then the three-necked flask was placed in a 70 °C oil bath for 7 h of reaction under nitrogen protection throughout. After the reaction was completed, the product was centrifuged at 10000 r / min for 5 min. The supernatant was discarded, and the solid was washed three times with petroleum ether. The centrifuged product was then dried in a 50 °C vacuum oven to constant weight.

[0052] (2) Preparation of cluster-luminescent polymer: 0.5 g of maleic anhydride copolymer microspheres were added to a 50 mL round-bottom flask, and excess ammonia gas was introduced to react with the microspheres to prepare amination polymer microspheres. The amination polymer microspheres were placed in a tube furnace and heated at 150 °C under nitrogen protection for 12 h to obtain maleimide polymer microspheres, which were denoted as cluster-luminescent polymer 3.

[0053] Example 4:

[0054] (1) Preparation of maleic anhydride copolymer microspheres: 2.45 g maleic anhydride, 2.30 mL vinyl acetate and 0.035 g azobisisobutyronitrile were added to a 250 mL three-necked flask, followed by 25 mL n-butyl acetate. After ultrasonic dissolution, the mixture was connected to the reaction vessel. Nitrogen gas was purged through the reaction system for 30 min, and then the three-necked flask was placed in a 70 °C oil bath for 7 h of reaction under nitrogen protection throughout. After the reaction was completed, the product was centrifuged at 10000 r / min for 5 min. The supernatant was discarded, and the solid was washed three times with petroleum ether. The centrifuged product was then dried in a 50 °C vacuum oven to constant weight.

[0055] (2) Preparation of cluster-luminescent polymer: 0.5 g of maleic anhydride copolymer microspheres were added to a 50 mL round-bottom flask, and excess ammonia gas was introduced to react with the microspheres to prepare amination polymer microspheres. The amination polymer microspheres were placed in a tube furnace and heated at 160 °C under nitrogen protection for 12 h to obtain maleimide polymer microspheres, which were designated as cluster-luminescent polymer 4.

[0056] Example 5:

[0057] (1) Preparation of maleic anhydride copolymer microspheres: 2.45 g maleic anhydride, 2.30 mL vinyl acetate and 0.035 g azobisisobutyronitrile were added to a 250 mL three-necked flask, followed by 25 mL n-butyl acetate. After ultrasonic dissolution, the mixture was connected to the reaction vessel. Nitrogen gas was purged through the reaction system for 30 min, and then the three-necked flask was placed in a 70 °C oil bath for 7 h of reaction under nitrogen protection throughout. After the reaction was completed, the product was centrifuged at 10000 r / min for 5 min. The supernatant was discarded, and the solid was washed three times with petroleum ether. The centrifuged product was then dried in a 50 °C vacuum oven to constant weight.

[0058] (2) Preparation of cluster-luminescent polymer: 0.5 g of maleic anhydride copolymer microspheres were added to a 50 mL round-bottom flask, and excess ammonia gas was introduced to react with the microspheres to prepare amination polymer microspheres. The amination polymer microspheres were placed in a tube furnace and heated at 170 °C under nitrogen protection for 12 h to obtain maleimide polymer microspheres, which were denoted as cluster-luminescent polymer 5.

[0059] Example 6:

[0060] (1) Preparation of maleic anhydride copolymer microspheres: 2.45 g maleic anhydride, 2.30 mL vinyl acetate and 0.035 g azobisisobutyronitrile were added to a 250 mL three-necked flask, followed by 25 mL n-butyl acetate. After ultrasonic dissolution, the mixture was connected to the reaction vessel. Nitrogen gas was purged through the reaction system for 30 min, and then the three-necked flask was placed in a 70 °C oil bath for 7 h of reaction under nitrogen protection throughout. After the reaction was completed, the product was centrifuged at 10000 r / min for 5 min. The supernatant was discarded, and the solid was washed three times with petroleum ether. The centrifuged product was then dried in a 50 °C vacuum oven to constant weight.

[0061] (2) Preparation of cluster-luminescent polymer: 0.5 g of maleic anhydride copolymer microspheres were added to a 50 mL round-bottom flask, and excess ammonia gas was introduced to react with the microspheres to prepare amination polymer microspheres. The amination polymer microspheres were placed in a tube furnace and heated at 180 °C under nitrogen protection for 12 h to obtain maleimide polymer microspheres, which were designated as cluster-luminescent polymer 6.

[0062] Table 1

[0063]

[0064] Application Example 1:

[0065] Preparation of light conversion composite film: 50g of polyethylene and 0.5g of the amination polymer microspheres prepared in Example 1 were blended in a twin-screw extruder at 170°C and hot-pressed at 170°C for 10 min to obtain light conversion composite film.

[0066] Application Example 2:

[0067] Preparation of light conversion composite film: 50g of polyethylene and 0.5g of maleimide polymer microspheres prepared in Example 5 were blended in a twin-screw extruder at 170°C and hot-pressed at 170°C for 10 min to obtain light conversion composite film.

[0068] The present invention provides a light-converting microsphere with tunable emission wavelength and high quantum yield. Compared with traditional methods, it does not require complex chemical modification of cluster-luminescent polymers, the steps are simple and the cost is low. Moreover, this method can increase the fluorescence quantum yield of polymer microspheres to more than 40%. In addition, while improving the quantum yield, the emission range of the microspheres can be adjusted by changing the heat treatment temperature, overcoming the disadvantage that most traditional non-conjugated cluster-luminescent polymers emit blue light.

[0069] In summary, this invention provides a light-converting microsphere with tunable emission wavelength and high quantum yield, exhibiting excellent thermal stability and processability, and showing promising application prospects in fields such as agricultural light-converting films, anti-counterfeiting encryption, fluorescent dyes, and bioimaging.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing light-converting microspheres with tunable emission wavelength and high quantum yield, characterized in that, The preparation method includes the following steps: (1) Maleic anhydride, vinyl monomer and initiator are added to solvent, ultrasonically dissolved and mixed evenly to obtain reaction system. The reaction is carried out in the reaction system under inert gas protection. After the reaction, centrifugation is used to purify and dry to obtain maleic anhydride copolymer microspheres. (2) The maleic anhydride copolymer microspheres described in step (1) are reacted with amines and dried under vacuum to obtain amination polymer microspheres; then, the amination polymer microspheres are heated under inert gas protection to cause intramolecular cyclization to obtain maleimide polymer microspheres; the amination polymer microspheres and maleimide polymer microspheres are collectively referred to as light conversion microspheres; The amine is ammonia, methylamine, or ethylamine. The structure of the vinyl monomer is shown in Formula I below: Formula I, where R is a saturated alkyl group.

2. The method for preparing light-converting microspheres with tunable emission wavelength and high quantum yield according to claim 1, characterized in that, In step (1), the solvent is one or a mixture of two or more of the following: butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, benzyl acetate, phenyl acetate, ethyl butyrate, isoamyl butyrate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate, ethyl phenylacetate, propyl phenylacetate, butyl phenylacetate, and isoamyl phenylacetate; the initiator is one of azobisisobutyronitrile, benzoyl peroxide, and potassium persulfate.

3. A method for preparing light-converting microspheres with tunable emission wavelength and high quantum yield according to claim 1, characterized in that, The vinyl monomer is vinyl acetate.

4. The method for preparing light-converting microspheres with tunable emission wavelength and high quantum yield according to claim 1, characterized in that, In step (1), the concentration of maleic anhydride and vinyl monomer in the reaction system is 0.2-1.0 mol / L, the initiator is 0.5-4 wt% of the total monomer content, the reaction temperature is 70℃-90℃, and the reaction time is 5-8h; in step (2), the heating temperature is 140℃-180℃, and the heating time is 6-12h.

5. The method for preparing light-converting microspheres with tunable emission wavelength and high quantum yield according to claim 1, characterized in that, In step (2), the amine treatment not only expands the emission wavelength range of the amination polymer microspheres to 350-550 nm, but also increases the quantum yield of the amination polymer microspheres to 45.24%.

6. The method for preparing light-converting microspheres with tunable emission wavelength and high quantum yield according to claim 1, characterized in that, In step (2), after the amination polymer microspheres are heated, the maximum emission wavelength of the prepared maleimide-based polymer microspheres is red-shifted to 550-650 nm, and the quantum yield is increased to 5%-9%.

7. A light-converting microsphere with tunable emission wavelength and high quantum yield, characterized in that, The light-converting microspheres are amination polymer microspheres or maleimide polymer microspheres prepared by any of the preparation methods described in claims 1-6. The amination polymer microspheres are shown in Formula II below, and the maleimide polymer microspheres are shown in Formula III below. Formula II Formula III In the formula, n is a positive integer.

8. The application of a light-converting microsphere with tunable emission wavelength and high quantum yield prepared by the preparation method according to any one of claims 1-6, characterized in that, The light-converting microspheres are mixed with a polymer matrix to prepare a transparent light-converting composite material that emits blue or red light. The light-converting microspheres are 1 to 2 parts per 100 parts by weight of the polymer matrix.

9. The application according to claim 8, characterized in that, The polymer matrix is ​​one or a combination of two or more of polyvinyl alcohol, polyurethane, polyethylene, polypropylene, polyvinyl chloride, and polyoxyethylene.

10. The application according to claim 8, characterized in that, The light conversion composite material is used in agricultural light conversion films and solar photovoltaic cell light conversion films.

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