1. A fluorescent polymer nanoparticle with dynamic fluorescence characteristics, which is prepared by the following method: dissolving a spiropyran monomer and an AIE monomer in a vinyl monomer in advance, preparing a monomer miniemulsion through pre-emulsification and ultrasonic emulsification treatment, and preparing fluorescent polymer nanoparticles with dynamic fluorescence characteristics in monomer droplets through free radical polymerization reaction of the vinyl monomer; the total mass usage of the spiropyran monomer and the AIE monomer is 0.01-20% (preferably 0.05-10%) of the mass usage of the vinyl monomer, wherein the mass usage of the AIE monomer is 5-300% (preferably 10-200%) of the mass usage of the spiropyran monomer;

the spiropyran monomer is a spiropyran organic compound with double bonds and photo-induced isomerization characteristics, and is selected from at least one of the following compounds:

the AIE functional monomer is an AIE molecule containing polymerizable vinyl and capable of generating FRET effect with a spiropyran organic compound;

the vinyl monomer is selected from at least one of the following: acrylate or methacrylate monomer, vinyl acetate, styrene, hydroxyalkyl methacrylate, hydroxyalkyl acrylate, acrylamide, N-hydroxyalkyl acrylamide, methacrylic acid, acrylic acid, dimethylaminoethyl methacrylate, glycidyl acrylate and glycidyl methacrylate, wherein the structure of the monomer is shown as formula (I);

in the formula (I), R₁Is H or CH₃；R₂Is aliphatic straight chain or branched chain alkyl or cyclic alkyl or phenyl or benzyl of C1-C30.

2. The fluorescent polymeric nanoparticle with dynamic fluorescent properties of claim 1, wherein: the reaction conditions of the free radical copolymerization reaction are as follows: under the action of oil-soluble initiator or water-soluble initiator, reacting for 0.5-24 h (preferably 1-24 h) at 25-95 deg.C (preferably 30-85 deg.C) under the protection of nitrogen.

3. The fluorescent polymeric nanoparticle with dynamic fluorescent properties of claim 1, wherein: the vinyl monomer is at least one selected from methyl methacrylate, octadecyl methacrylate, lauryl methacrylate, isobornyl methacrylate, N-hexyl methacrylate, cyclohexyl methacrylate, N-butyl methacrylate, butyl acrylate, ethyl acrylate, isooctyl acrylate, methyl acrylate, styrene, vinyl acetate and N-hydroxyethyl acrylamide.

4. A method for preparing fluorescent polymeric nanoparticles with dynamic fluorescence characteristics according to any one of claims 1 to 3, comprising the following steps:

(1) dissolving an emulsifier in water to obtain an emulsifier aqueous solution, wherein the mass consumption of the emulsifier is 0.01-10% of the mass consumption of the water; the emulsifier is selected from at least one of the following: tween series emulsifier, OP series emulsifier, MOA series emulsifier, alkyl sulfonate emulsifier, alkylbenzene sulfonic acid type emulsifier, alkyl sulfate emulsifier, alkyl carboxylate emulsifier, alkyl trimethyl ammonium halide emulsifier, betaine emulsifier;

(2) dissolving a spiropyran monomer and an AIE monomer into a solution of a vinyl monomer and a co-stabilizer to obtain an oil phase solution, wherein the total mass usage of the spiropyran monomer and the AIE monomer is 0.05-10% of the mass usage of the vinyl monomer, the mass usage of the AIE monomer is 10-200% of the mass usage of the spiropyran monomer, and the mass usage of the co-stabilizer is 0-10% of the mass usage of the vinyl monomer;

the co-stabilizer is selected from at least one of the following: aliphatic straight chain or branched chain alkane of C14-C22, aliphatic alcohol of C14-C22;

(3) adding the oil phase solution obtained in the step (2) into the emulsifier aqueous solution obtained in the step (1), wherein the total mass consumption of the monomers is 1-35% of the mass consumption of water, and then pre-emulsifying for 5-90 min under the magnetic stirring of 100-1000 rpm to obtain a coarse emulsion; then placing the container filled with the coarse emulsion in an ice-water bath, and carrying out ultrasonic treatment for 0.5-90 min under the power of 20-900W to prepare a monomer fine emulsion; after nitrogen is introduced to remove oxygen, the temperature is adjusted to 25-95 ℃, and the reaction is carried out for 0.5-24 h under the protection of nitrogen, so as to prepare the fluorescent polymer nano particle emulsion with dynamic fluorescence characteristic;

and the initiator is introduced by the following means a or b:

in the step (2), adding an oil-soluble initiator into the monomer mixed solution, wherein the mass usage of the oil-soluble initiator is 0.05-5% of the total mass usage of the vinyl monomer;

mode b: in the step (3), a water-soluble initiator is added into the monomer miniemulsion, wherein the mass usage of the water-soluble initiator is 0.05-5% of the total mass usage of the vinyl monomer.

5. The method of claim 4The preparation method is characterized by comprising the following steps: in the step (1), the tween series emulsifier is one or a combination of more of tween-20, tween-40, tween-60 or tween-80; the OP series emulsifier is one or a combination of more than one of OP-7, OP-10, OP-15 or OP-20; the MOA series emulsifier is one or a combination of more of MOA-3, MOA-7 and MOA-9; the alkyl sulfonate emulsifier is R₃-SO₃M, wherein R₃Is a fatty chain of C12-C20, M is Na⁺Or K⁺(ii) a The alkylbenzene sulfonate emulsifier is R₄-C₆H₄-SO₃M, wherein R₄Is a fatty chain of C10-C18, M is Na⁺Or K⁺(ii) a Alkyl carboxylate emulsifiers are R₅-COOM, wherein R₅Is a fatty chain of C9-C21, M is Na⁺Or K⁺(ii) a Alkyl trimethyl ammonium halide emulsifier is R₆N⁺(CH₃)₃X^-Wherein R is₆Is a C12-C20 aliphatic chain, and X is Cl or Br; the betaine emulsifier is carboxylic betaine or sulfobetaine.

6. The method of claim 4, wherein: the emulsifier is selected from at least one of alkyl sulfate emulsifier, alkyl sulfonate emulsifier, alkyl benzene sulfonate emulsifier, alkyl trimethyl ammonium halide emulsifier and sulfobetaine, preferably at least one of sodium dodecyl sulfate, cetyl trimethyl ammonium bromide and dodecyl dimethyl hydroxypropyl sulfobetaine.

7. The method of claim 4, wherein: in the step (3), the oil-soluble initiator is selected from at least one of the following: azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptonitrile, dibenzoyl peroxide, diisopropyl peroxydicarbonate, lauroyl peroxide; wherein the mass usage of the oil-soluble initiator is 0.05-5% of the mass usage of the vinyl monomer.

8. The method of claim 4, wherein: in the step (3), theThe water-soluble initiator is selected from at least one of the following: 2, 2' -azobisisobutylamidine dihydrochloride, azobiscyanovaleric acid, persulfate, an oxidizing agent and a reducing agent; the reducing agent is sulfite, thiosulfate, bisulfite, ascorbate or oxalic acid; the oxidant is hydrogen peroxide or persulfate; the cation of the salt is Na⁺、K⁺Or NH₄ ⁺。

9. Use of the fluorescent polymeric nanoparticles with dynamic fluorescence properties according to claim 1 for the preparation of coatings with dynamically adjustable fluorescence color.

10. The use according to claim 9, characterized in that the use is in particular: the emulsion of the fluorescent polymer nano-particles with the dynamic fluorescence characteristic is coated on the surface of a base material and is filmed at the temperature of 20-180 ℃ to prepare the functional coating with the dynamic fluorescence characteristic.

(II) background of the invention

Fluorescent Polymer Nanoparticles (FPNPs) have great application prospects in the fields of anti-counterfeiting, sensing, imaging, information encryption and the like [ nat. commun.2020,11,2460; nanoscale 2018,10, 1617-; adv.funct.mater.2019,29,1904992. The fluorescence emission of the traditional FPNPs only shows static and single fluorescence emission, and the FPNPs with dynamic fluorescence property attract the attention of a large number of researchers due to special fluorescence emission behaviors, such as light responsiveness, acid-base responsiveness and the like. At present, the preparation strategies of FPNPs with dynamic fluorescence properties mainly include the development of novel responsive dyes with complex molecular structures, the construction of Fluorescence Resonance Energy Transfer (FRET) systems using quantum dots or using photochromic dyes [ j.am.chem.soc.2012,134, 12091-12097; nat. commun.2014,5,3799; angew. chem. int. ed.2015,54, 5360-. Wherein the fluorescence color in the spectral range defined by the fluorescence donor and the fluorescence acceptor can be adjusted by means of the FRET effect. Currently, this is accomplished primarily by varying the donor-acceptor ratio, which requires the preparation of a range of dye gradient ratios of FPNPs.

The invention provides a miniemulsion reaction system, utilizes the copolymerization reaction of a conventional monomer, a spiropyran monomer and an AIE monomer, constructs FPNPs with dynamic fluorescence characteristics under the regulation and control of FRET and AIE synergistic action in one step, and explores the application of the FPNPs in the construction of a luminescent coating with adjustable fluorescence color.

Disclosure of the invention

The invention aims to provide FPNPs (fluorescent protein) containing an AIE (electron emission element) and a spiropyran group and having dynamic fluorescence characteristics, wherein the AIE emission element and the spiropyran group are connected to a polymer matrix in a chemical bond mode, and the FPNPs can realize the conversion from the fluorescence of the AIE emission element to the fluorescence of an MC emission element under the excitation of light based on the photoisomerization characteristics of the spiropyran and the limited luminescence characteristics of the AIE emission element.

The second object of the present invention is to provide a method for preparing FPNPs having dynamic fluorescence characteristics, wherein the method comprises the step of introducing an AIE emitting group and a spiropyran emitting group into a polymer matrix in a chemical bond manner through a copolymerization reaction of an AIE monomer, a spiropyran monomer and a general-purpose monomer by using a miniemulsion polymerization technique, so as to prepare the FPNPs having dynamic fluorescence characteristics.

The third purpose of the invention is to realize the application of FPNPs with dynamic fluorescence characteristics in the coating with dynamically adjustable fluorescence color.

In order to achieve the purpose, the invention adopts the technical scheme that:

in a first aspect, the present invention provides FPNPs with dynamic fluorescence characteristics, which are prepared by the following method: dissolving a spiropyran monomer and an AIE monomer in a general vinyl monomer in advance, preparing a monomer miniemulsion through pre-emulsification and ultrasonic emulsification treatment, and preparing FPNPs with dynamic fluorescence characteristics in monomer droplets through free radical polymerization reaction of the vinyl monomer; the total mass usage of the spiropyran monomer and the AIE monomer is 0.01-20% of the mass usage of the vinyl monomer, wherein the mass usage of the AIE monomer is 5-300% of the mass usage of the spiropyran monomer;

the spiropyran monomer is a spiropyran organic compound with double bonds and photo-induced isomerization characteristics, and is selected from at least one of the following compounds:

the AIE functional monomer is an AIE molecule containing polymerizable vinyl and capable of generating FRET effect with a spiropyran organic compound;

the vinyl monomer is selected from at least one of the following: the structure of the acrylic ester or methacrylic ester monomer is shown as the formula (I), vinyl acetate, styrene, hydroxyalkyl methacrylate (the number of alkyl carbon atoms is preferably 1-6), hydroxyalkyl acrylate (the number of alkyl carbon atoms is preferably 1-6), acrylamide, N-hydroxyalkyl acrylamide (the number of alkyl carbon atoms is preferably 1-6), methacrylic acid, acrylic acid, dimethylamino ethyl methacrylate, glycidyl acrylate and glycidyl methacrylate;

formula (I)

In the formula (I), R₁Is H or CH₃；R₂Is aliphatic straight chain or branched chain alkyl or cyclic alkyl or phenyl or benzyl of C1-C30.

The FPNPs are composed of a spiropyran group, an AIE emitting group and a polymer matrix, wherein in each polymer nanoparticle, two fluorescent emitting groups are linked to the matrix polymer in a chemical bond mode, and a FRET effect can be generated between the two emitting groups.

Preferably, the reaction conditions of the radical copolymerization are as follows: under the action of oil-soluble initiator or water-soluble initiator, reacting for 0.5-24 h at 25-95 ℃ under the protection of nitrogen.

Preferably, the vinyl monomer is at least one selected from the group consisting of methyl methacrylate, octadecyl methacrylate, lauryl methacrylate, isobornyl methacrylate, N-hexyl methacrylate, cyclohexyl methacrylate, N-butyl methacrylate, butyl acrylate, ethyl acrylate, isooctyl acrylate, methyl acrylate, styrene, vinyl acetate, and N-hydroxyethyl acrylamide.

Preferably, the total mass usage amount of the spiropyran monomer and the AIE monomer is 0.05-10% of the mass usage amount of the vinyl monomer, wherein the mass usage amount of the AIE monomer is 10-200% of the mass usage amount of the spiropyran monomer.

Preferably, the Z-average particle diameter of the FPNPs with dynamic fluorescence characteristics is 30-200 nm.

The inventors have found that FPNPs having dynamic fluorescence characteristics emit strong fluorescence under uv irradiation, and at the same time, the fluorescence color of FPNPs changes gradually as the uv irradiation time is prolonged. Specifically, when such particles are exposed to ultraviolet radiation, the particles first emit a fluorescent color consistent with the characteristic fluorescence of the AIE emitter, but as the exposure time to ultraviolet radiation increases, the fluorescent color of the particles gradually changes, eventually becoming red fluorescence (the characteristic fluorescent color of open-ring spiropyran), and the color change process can be captured by the naked eye.

In a second aspect, the present invention provides a method for preparing FPNPs having dynamic fluorescence characteristics, the method comprising the steps of:

(1) dissolving an emulsifier in water to obtain an emulsifier aqueous solution, wherein the mass consumption of the emulsifier is 0.01-10% of the mass consumption of the water; the emulsifier is selected from at least one of the following: tween series emulsifier, OP series emulsifier, MOA series emulsifier, alkyl sulfonate emulsifier, alkylbenzene sulfonic acid type emulsifier, alkyl sulfate emulsifier, alkyl carboxylate emulsifier, alkyl trimethyl ammonium halide emulsifier, betaine emulsifier;

(2) dissolving a spiropyran monomer and an AIE monomer into a solution of a vinyl monomer and a co-stabilizer to obtain an oil phase solution, wherein the total mass usage of the spiropyran monomer and the AIE monomer is 0.05-10% of the mass usage of the vinyl monomer, the mass usage of the AIE monomer is 10-200% of the mass usage of the spiropyran monomer, and the mass usage of the co-stabilizer is 0-10% of the mass usage of the vinyl monomer;

the co-stabilizer is selected from at least one of the following: aliphatic straight chain or branched chain alkane of C14-C22, aliphatic alcohol of C14-C22;

(3) adding the oil phase solution obtained in the step (2) into the emulsifier aqueous solution obtained in the step (1), wherein the total mass consumption of the monomers is 1-35% of the mass consumption of water, and then pre-emulsifying for 5-90 min under the magnetic stirring of 100-1000 rpm to obtain a coarse emulsion; then placing the container filled with the coarse emulsion in an ice-water bath, and carrying out ultrasonic treatment for 0.5-90 min under the power of 20-900W to prepare a monomer fine emulsion; after nitrogen is introduced to remove oxygen, the temperature is adjusted to 25-95 ℃, and the mixture reacts for 0.5-24 hours under the protection of nitrogen, so that the FPNPs emulsion with dynamic fluorescence characteristic is prepared;

and the initiator is introduced by the following means a or b:

in the step (2), adding an oil-soluble initiator into the monomer mixed solution, wherein the mass usage of the oil-soluble initiator is 0.05-5% of the total mass usage of the vinyl monomer;

mode b: in the step (3), a water-soluble initiator is added into the monomer miniemulsion, wherein the mass usage of the water-soluble initiator is 0.05-5% of the total mass usage of the vinyl monomer.

In the step (1), the tween series emulsifier can be one or a combination of more of tween-20, tween-40, tween-60 or tween-80; the OP series emulsifier can be one or a combination of more than one of OP-7, OP-10, OP-15 or OP-20; the MOA series emulsifier can be one or a combination of more of MOA-3, MOA-7 and MOA-9; the alkyl sulfonate emulsifier may be R₃-SO₃M, wherein R₃Is a fatty chain of C12-C20, M is Na⁺Or K⁺(ii) a The alkylbenzene sulfonate emulsifier may be R₄-C₆H₄-SO₃M, wherein R₄Is a fatty chain of C10-C18, M is Na⁺Or K⁺(ii) a The alkyl carboxylate emulsifier may be R₅-COOM, wherein R₅Is a fatty chain of C9-C21, M is Na⁺Or K⁺(ii) a The alkyl trimethyl ammonium halide emulsifier may be R₆N⁺(CH₃)₃X^-Wherein R is₆Is a C12-C20 aliphatic chain, and X is Cl or Br; the betaine emulsifier may be a carboxylic betaine (R)₇N⁺(CH₃)₂CH₂COO^-Wherein R is₇Fatty chain of C12-C18), sulfobetaine (R)₈N⁺(CH₃)₂CH₂CH₂SO₃ ^-Or R₉N⁺(CH₃)₂CH₂CH₂CH₂SO₃ ^-Wherein R is₈And R₉Fatty chain of C12-C18).

In view of the stability of the particles during polymerization, the emulsifier is preferably at least one of an alkyl sulfate emulsifier, an alkyl sulfonate emulsifier, an alkyl benzene sulfonate emulsifier, an alkyl trimethyl ammonium halide emulsifier, and a sulfobetaine, and more preferably at least one of sodium dodecyl sulfate, cetyl trimethyl ammonium bromide, and dodecyl dimethyl hydroxypropyl sulfobetaine.

The co-stabilizer is preferably an aliphatic linear or branched alkane of C16 to C22, more preferably n-hexadecane, in view of the stability of the droplets.

In step (3) of the present invention, the oil-soluble initiator is selected from at least one of: azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptonitrile, dibenzoyl peroxide, diisopropyl peroxydicarbonate, lauroyl peroxide. Wherein the mass usage of the oil-soluble initiator is 0.05-5% of the mass usage of the vinyl monomer.

In step (3) of the present invention, the water-soluble initiator is selected from at least one of: 2, 2' -azobisisobutylamidine dihydrochloride, azobiscyanovaleric acid, persulfate, an oxidizing agent and a reducing agent; the reducing agent is sulfite, thiosulfate, bisulfite, ascorbate or oxalic acid; the oxidant is hydrogen peroxide or persulfate; the cation of the salt may be Na⁺、K⁺Or NH₄ ⁺. The persulfate is preferably ammonium persulfate or potassium persulfate; the reducing agent is preferably ascorbate.

In the step (3) of the present invention, the polymerization reaction temperature is more preferably 30 to 85 ℃ in view of the initiation temperature of the initiator; the reaction time is more preferably 1 to 24 hours; in order to prevent the miniemulsion from being overheated in the ultrasonic process, the container filled with the macroemulsion is placed in an ice-water bath for ultrasonic treatment, the ultrasonic power is preferably 60W-500W, and the ultrasonic time is preferably 5 min-45 min.

In step (2) of the present invention, the vinyl monomer is preferably at least one selected from the group consisting of methyl methacrylate, octadecyl methacrylate, lauryl methacrylate, isobornyl methacrylate, N-hexyl methacrylate, cyclohexyl methacrylate, N-butyl methacrylate, butyl acrylate, ethyl acrylate, isooctyl acrylate, methyl acrylate, styrene, vinyl acetate, and N-hydroxyethyl acrylamide.

The inventors have intensively studied and found that the adjustment of the polymer matrix can be carried out simultaneouslyIsomerism behaviour and AIE behaviour, which in turn affects the FRET effect between the fluorescent donor AIE emission and the fluorescent acceptor MC emission. Wherein the content of the first and second substances,the occurrence of the isomerisation reaction requires sufficient free volume in the polymer matrix around its molecules, so that the more flexible the polymer matrix is,the faster the isomerization reaction; in addition, the improvement of the flexibility of the polymer matrix can cause the reduction of the polarity of the matrix, and the improvement of the flexibility of the polymer matrix is not beneficial to the stable existence of the MC emitting groups in the matrix because the polarity of MC in two isomeric forms of the spiropyran is larger than that of SP. Under the simultaneous action of the flexibility and polarity of the polymer matrix, the MC content in different polymer matrixes is different. At the same time, the polymer matrix affects the degree of aggregation of the AIE emitting clusters, and thus the fluorescence of the AIE emitting clusters, including emission wavelength and intensity, among others. In different polymer matrices, there is a significant difference in FRET efficiency between AIE and MC emission groups, which determines the rate and extent of fluorescence color shift of the particles under continuous uv illumination.

In a group of specific embodiments of the present invention, the vinyl monomer for preparing the polymer matrix comprises methyl methacrylate, and examples of examples 1, comparative examples 3 and comparative examples 4 include that the vinyl monomer of example 1 only comprises methyl methacrylate, the flexibility of the polymer matrix is poor, the fluorescence color of the emulsion gradually changes from blue to pink purple under continuous ultraviolet irradiation, and the fluorescence color of the emulsion is stable when the irradiation time reaches about 20 minutes; the vinyl monomer of the comparative example 3 is composed of a copolymer of methyl methacrylate and butyl acrylate, has good flexibility, and the fluorescence color of the emulsion can be gradually changed from blue to pink under the continuous ultraviolet irradiation, and can be stable when the irradiation time reaches about 15 minutes. However, when the content of butyl acrylate in the vinyl monomer is continuously increased, namely the comparative example 4, the fluorescence color of the emulsion can be gradually changed from blue to dark pink under the continuous ultraviolet irradiation, and when the irradiation time reaches about 6 minutes, the fluorescence color of the emulsion can be stabilized. Therefore, in order to achieve faster color transition, the vinyl monomer is added with a certain amount of soft monomer (the monomer with lower homopolymer glass transition temperature, such as at least one of octadecyl methacrylate, lauryl methacrylate, isobornyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, n-butyl methacrylate, butyl acrylate, ethyl acrylate, isooctyl acrylate, methyl acrylate and vinyl acetate) to the hard monomer (such as at least one of methyl methacrylate and styrene) to effectively improve the flexibility of the polymer matrix; if a larger contrast ratio before and after the fluorescence color conversion is to be realized (namely the fluorescence color of the final emulsion is redder), not only a certain amount of soft monomer needs to be added, but also the content of the soft monomer needs to be regulated to regulate the polarity of the polymer, so that the aim of stably existing MC units is fulfilled. In a preferred embodiment, the vinyl monomer comprises at least one of methyl methacrylate and styrene (referred to as monomer a) and at least one of octadecyl methacrylate, lauryl methacrylate, isobornyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, n-butyl methacrylate, butyl acrylate, ethyl acrylate, isooctyl acrylate, methyl acrylate and vinyl acetate (referred to as monomer B), and the mass percentage of monomer B in the vinyl monomer is 0-80%.

In a third aspect, the invention provides the use of the FPNPs with dynamic fluorescence properties for the preparation of coatings with dynamically tunable fluorescence color.

Further, the application specifically comprises: coating the emulsion of FPNPs with dynamic fluorescence characteristic on the surface of a substrate, and forming a film (generally 1 min-48 h for film formation) at 20-180 ℃ to obtain the functional coating with dynamic fluorescence characteristic.

Further, the coating process is selected from one of spray coating, spin coating, dip coating, blade coating, and drop coating.

Still further, the substrate is selected from one of a glass substrate, a metal substrate, a polymer film, a silicon wafer, and a mica sheet.

Furthermore, the mass of the functional coating with the dynamic fluorescence characteristic is 0.01-15 mg per square centimeter of the surface of the base material.

The dynamic fluorescence characteristics of the FPNPs having dynamic fluorescence characteristics and the excellent processability and film-forming ability of the present invention allow various applications such as warning labels, dynamic decorative paintings, and multiple information encryption.

Compared with the prior art, the invention has the beneficial effects that: the invention prepares FPNPs with dynamic fluorescence property simply and conveniently through free radical polymerization under the framework of miniemulsion polymerization technology, combines spiropyran with AIE emission group, and realizes the gradual emission of the fluorescence of polymer nano particles by taking ultraviolet light and visible light as control switches based on FRET effect. The FRET-PNPs of the invention can exhibit dynamic changes in fluorescence properties (color and PL intensity) on a time scale of several minutes under light irradiation. Unlike strategies that control emission color by adjusting the FRET donor to acceptor content ratio, the emission color of FRET-PNPs of the invention is adjusted by the composition of the polymer matrix and used to simultaneously adjust the AIE properties and the synergistic variation of the FRET process, enabling dynamic color tunability and fluorescence intensity. This property is well suited for dynamic decoration and multiple encryption applications. In addition, time-dependent FRET-PNPs are convenient and conducive to the formation of polymer films without the need to compensate for fluorescence properties, providing feasibility for other applications, such as fluorescence optical memory. In a word, the invention does not need complex molecular design and fussy preparation process, and the proposed strategy of 'polymer matrix regulation and control of fluorescence technology' provides a new direction for the design and performance optimization of various fluorescent materials for innovative application.

(IV) detailed description of the preferred embodiments

The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto:

example 1:

1.0g of sodium lauryl sulfate was weighed out and dissolved in 125g of water to obtain an aqueous emulsifier solution. Then 0.04g of AIE-1, 0.06g of SP-1, 10g of methyl methacrylate, 0.25g of azobisisobutyronitrile and 0.6g of n-hexadecane are weighed in sequence and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into the emulsifier aqueous solution, pre-emulsifying for 5min at a magnetic stirring speed of 1000rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and performing ultrasonic treatment for 5min at a power of 450W to obtain a stable monomer miniemulsion; and after nitrogen is introduced and oxygen is removed, adjusting the reaction temperature to 65 ℃, and reacting for 10 hours under the protection of nitrogen to prepare the FPNPs emulsion with dynamic fluorescence property.

The Z-average particle size of the FPNPs measured by a dynamic light scattering nanometer particle size analyzer is 111 nm. Diluting the prepared emulsion to the solid content of 1 wt%, gradually changing the initial blue fluorescence of the FPNPs emulsion with dynamic fluorescence property to pink purple under the irradiation of 365nm ultraviolet light, and stabilizing the fluorescence color of the emulsion when the irradiation time reaches 20 min. An ultraviolet spectrophotometer (UV-2600, Shimadazu) is adopted to record the ultraviolet-visible light absorption spectrum of the FPNPs emulsion in the wavelength range of 200 nm-700 nm after ultraviolet irradiation for different time, and the characteristic absorption peak of MC-1 is enhanced along with the extension of the ultraviolet irradiation time.

And (3) recording the fluorescence spectrogram of the FPNPs emulsion in the wavelength range of 400-700 nm after ultraviolet irradiation for different time under the 365nm ultraviolet excitation condition by using an F-4600 fluorescence spectrum analyzer (F-4600, Hitachi). It was found that the characteristic fluorescence emission peak of AIE-1 becomes weaker and stronger as the ultraviolet irradiation time in the fluorescence spectrum increases.

Diluting the prepared emulsion to the solid content of 5 wt%, taking about 2mg of the emulsion, coating the emulsion on a clean glass sheet with the thickness of 2cm multiplied by 2cm in a spin coating mode, and drying the glass sheet for 10min at the temperature of 100 ℃ to obtain the functional coating with the dynamic fluorescence characteristic. The FPNPs coating with dynamic fluorescence characteristics gradually changes from initial blue fluorescence to pink purple under continuous ultraviolet lamp irradiation.

Comparative example 1:

1.0g of sodium lauryl sulfate was weighed out and dissolved in 125g of water to obtain an aqueous emulsifier solution. Then 0.04g of AIE-1, 10g of methyl methacrylate, 0.25g of azobisisobutyronitrile and 0.6g of n-hexadecane are weighed in sequence and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into the emulsifier aqueous solution, pre-emulsifying for 5min at a magnetic stirring speed of 1000rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and performing ultrasonic treatment for 5min at a power of 450W to obtain a stable monomer miniemulsion; and adjusting the reaction temperature to 65 ℃, and reacting for 10 hours under the protection of nitrogen to obtain the FPNPs emulsion.

The Z-average particle size of the FPNPs was 102nm as measured by a dynamic light scattering nano-particle sizer. The prepared emulsion is diluted to have a solid content of 1 wt%, under the irradiation of 365nm ultraviolet light, the FPNPs emulsion emits blue fluorescence, and the fluorescence color of the emulsion does not change along with the extension of the ultraviolet irradiation time. The emulsion has only characteristic AIE-1 emission peak in the corresponding fluorescence spectrum, and the characteristic AIE-1 fluorescence emission peak hardly changes with the prolonging of the ultraviolet irradiation time.

Comparative example 2:

1.0g of sodium lauryl sulfate was weighed out and dissolved in 125g of water to obtain an aqueous emulsifier solution. Then 0.06g of SP-1, 10g of methyl methacrylate, 0.25g of Azobisisobutyronitrile (AIBN) and 0.6g of n-hexadecane are weighed in sequence and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into the emulsifier aqueous solution, pre-emulsifying for 5min at a magnetic stirring speed of 1000rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and performing ultrasonic treatment for 5min at a power of 450W to obtain a stable monomer miniemulsion; and adjusting the reaction temperature to 65 ℃, and reacting for 10 hours under the protection of nitrogen to obtain the FPNPs emulsion.

The Z-average particle size of the FPNPs measured by a dynamic light scattering nanometer particle sizer is 104 nm. The prepared emulsion is diluted to have a solid content of 1 wt%, and under the continuous irradiation of a 365nm ultraviolet lamp, the fluorescence of the emulsion is changed from colorless at the beginning to extremely weak red fluorescence, and the red fluorescence of the emulsion is stronger and stronger along with the extension of the irradiation time. The characteristic absorption peak of MC-1 in the corresponding ultraviolet-visible light absorption spectrum of the emulsion becomes stronger with the prolonging of the ultraviolet irradiation time. The corresponding fluorescence spectrum of the emulsion only has the characteristic emission peak of MC-1, and the characteristic fluorescence emission peak of MC-1 is stronger and stronger along with the extension of the ultraviolet irradiation time.

Comparative example 3:

1.0g of sodium lauryl sulfate was weighed out and dissolved in 125g of water to obtain an aqueous emulsifier solution. Then 0.04g of AIE-1, 0.06g of SP-1, 6g of methyl methacrylate, 4g of butyl acrylate, 0.25g of azodiisobutyronitrile and 0.6g of n-hexadecane are weighed in sequence and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into the emulsifier aqueous solution, pre-emulsifying for 5min at a magnetic stirring speed of 1000rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and performing ultrasonic treatment for 5min at a power of 450W to obtain a stable monomer miniemulsion; and after nitrogen is introduced and oxygen is removed, adjusting the reaction temperature to 65 ℃, and reacting for 10 hours under the protection of nitrogen to prepare the FPNPs emulsion with dynamic fluorescence property.

The Z-average particle size of the FPNPs emulsion is 107nm measured by a dynamic light scattering nanometer particle sizer. The prepared emulsion is diluted to have a solid content of 1 wt%, under the irradiation of 365nm ultraviolet light, the FPNPs emulsion gradually changes from initial blue fluorescence to pink, and when the irradiation time reaches 15min, the fluorescence color of the emulsion is stable. The fluorescent color transition speed of comparative example 3 is faster compared to example 1. The characteristic absorption peak of MC-1 in the corresponding ultraviolet-visible light absorption spectrum of the emulsion becomes stronger with the prolonging of the ultraviolet irradiation time. The characteristic fluorescence emission peak of AIE-1 in the corresponding fluorescence spectrum of the emulsion is weaker and weaker along with the extension of the ultraviolet irradiation time, and the characteristic fluorescence emission peak of MC-1 is stronger and stronger. And in the final state, the absorption peak intensity and fluorescence intensity of MC-1 in comparative example 3 are both significantly greater than those of example 1, resulting in a redder final fluorescence color.

Diluting the prepared emulsion to the solid content of 5 wt%, taking about 2mg of the emulsion, coating the emulsion on a clean glass sheet with the thickness of 2cm multiplied by 2cm in a spin coating mode, and drying the glass sheet for 10min at the temperature of 100 ℃ to obtain the functional coating with the dynamic fluorescence characteristic. The FPNPs coating with dynamic fluorescence properties is gradually changed from initially blue fluorescence to pink under continuous uv lamp illumination.

Comparative example 4:

1.0g of sodium lauryl sulfate was weighed out and dissolved in 125g of water to obtain an aqueous emulsifier solution. Then 0.04g of AIE-1, 0.06g of SP-1, 2g of methyl methacrylate, 8g of butyl acrylate, 0.25g of azodiisobutyronitrile and 0.6g of n-hexadecane are weighed in sequence and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into the emulsifier aqueous solution, pre-emulsifying for 5min at a magnetic stirring speed of 1000rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and performing ultrasonic treatment for 5min at a power of 450W to obtain a stable monomer miniemulsion; and after nitrogen is introduced and oxygen is removed, adjusting the reaction temperature to 65 ℃, and reacting for 10 hours under the protection of nitrogen to prepare the FPNPs emulsion with dynamic fluorescence property.

The Z-average particle size of the FPNPs emulsion is 112nm measured by a dynamic light scattering nanometer particle sizer. Diluting the prepared emulsion until the solid content is 1 wt%, gradually changing the emulsion of the fluorescence gradual change polymer nano particles from initial blue fluorescence to dark pink under the irradiation of an ultraviolet lamp of 365nm, and stabilizing the fluorescence color of the emulsion when the irradiation time reaches 6 min. The fluorescent color transition speed of comparative example 4 is faster compared to example 1 and comparative example 3. The characteristic absorption peak of MC-1 in the corresponding ultraviolet-visible light absorption spectrum of the emulsion becomes stronger with the prolonging of the ultraviolet irradiation time. The characteristic fluorescence emission peak of AIE-1 in the corresponding fluorescence spectrum of the emulsion is weaker and weaker along with the extension of the ultraviolet irradiation time, and the characteristic fluorescence emission peak of MC-1 is stronger and stronger. And in the final state, the absorption peak intensity and fluorescence intensity of MC-1 in comparative example 4 are both significantly lower than those of example 1 and comparative example 3.

Diluting the prepared emulsion to the solid content of 5 wt%, taking about 2mg of the emulsion, coating the emulsion on a clean glass sheet with the thickness of 2cm multiplied by 2cm in a spin coating mode, and drying the glass sheet for 10min at the temperature of 100 ℃ to obtain the functional coating with the dynamic fluorescence characteristic. The FPNPs coating with dynamic fluorescence properties was graded from initially blue fluorescence to dark pink under continuous uv lamp illumination.

Example 2:

0.15g of the emulsifier MOA-9 was weighed out and dissolved in 12.5g of water to obtain an aqueous emulsifier solution. Then 0.003g of AIE-10, 0.007g of SP-1, 0.70g of methyl methacrylate, 0.30g of cyclohexyl methacrylate and 0.07g of n-hexadecane are weighed in sequence and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into an emulsifier aqueous solution, pre-emulsifying for 25min at a magnetic stirring speed of 700rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and performing ultrasonic treatment for 12min at a power of 360W to obtain a stable monomer miniemulsion; adding 0.025g of water-soluble initiator 2, 2' -azobisisobutylamidine dihydrochloride, introducing nitrogen to remove oxygen, adjusting the reaction temperature to 75 ℃, and reacting for 5 hours under the protection of nitrogen to prepare the FPNPs emulsion with dynamic fluorescence characteristics.

The Z-average particle size of the FPNPs emulsion is 83nm measured by a dynamic light scattering nanometer particle size analyzer. Diluting the prepared emulsion until the solid content is 1 wt%, gradually changing the blue fluorescence of the emulsion from the beginning to pink under the irradiation of 365nm ultraviolet light, and stabilizing the fluorescence color of the emulsion when the irradiation time reaches 15 min. The characteristic absorption peak of MC-1 in the corresponding ultraviolet-visible light absorption spectrum of the emulsion becomes stronger with the prolonging of the ultraviolet irradiation time. The characteristic fluorescence emission peak of AIE-10 in the corresponding fluorescence spectrum of the emulsion is weaker and weaker along with the extension of the ultraviolet irradiation time, and the characteristic fluorescence emission peak of MC-1 is stronger and stronger.

Diluting the prepared emulsion to the solid content of 5 wt%, taking about 2mg of the emulsion, coating the emulsion on a 2cm × 2cm glass sheet in a spraying mode, and baking the glass sheet at the temperature of 110 ℃ for 5min to obtain the FPNPs coating with the dynamic fluorescence characteristic. The FPNPs coating with dynamic fluorescence properties is gradually changed from initially blue fluorescence to pink under continuous uv lamp illumination.

Example 3:

0.275g of cetyltrimethylammonium bromide and 0.1g of MOA-9 were weighed out and dissolved in 12.5g of water to obtain an aqueous emulsifier solution. Then 0.008g of AIE-5, 0.012g of SP-2, 1.0g of methyl methacrylate, 0.50g of n-butyl methacrylate, 0.05g of oil-soluble initiator azodiisoheptanonitrile and 0.09g of n-hexadecane are weighed in sequence and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into the emulsifier aqueous solution, pre-emulsifying for 30min at a magnetic stirring speed of 500rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and performing ultrasonic treatment for 20min at a power of 300W to obtain a stable monomer miniemulsion; and after nitrogen is introduced to remove oxygen, adjusting the reaction temperature to 55 ℃, and reacting for 6 hours under the protection of nitrogen to prepare the FPNPs emulsion with the dynamic fluorescence characteristic.

The Z-average particle size of the FPNPs emulsion is 92nm measured by a dynamic light scattering nanometer particle size analyzer. Under the irradiation of 365nm ultraviolet light, the emulsion gradually changes from initial blue fluorescence to orange red, and when the irradiation time reaches 18min, the fluorescence color of the emulsion is stable. The characteristic absorption peak of MC-2 in the corresponding ultraviolet-visible light absorption spectrum of the emulsion becomes stronger with the prolonging of the ultraviolet irradiation time. The characteristic fluorescence emission peak of AIE-5 in the corresponding fluorescence spectrum of the emulsion is weaker and weaker along with the extension of the ultraviolet irradiation time, and the characteristic fluorescence emission peak of MC-2 is stronger and stronger.

Diluting the prepared emulsion to the solid content of 5 wt%, taking about 600mg of the emulsion, coating the emulsion on a 3cm × 5cm steel material in a spraying mode, and baking the emulsion at the temperature of 30 ℃ for 36 hours to obtain a FPNPs coating with dynamic fluorescence characteristics. The FPNPs coating with dynamic fluorescence properties was gradually changed from initially blue fluorescence to orange under continuous uv lamp illumination.

Example 4:

0.015g of sodium lauryl sulfate and 0.005g of MOA-7 were weighed out and dissolved in 12.5g of water to obtain an aqueous emulsifier solution. Then 0.0025g of AIE-6, 0.0025g of SP-3, 0.10g of octadecyl methacrylate, 0.40g of isobornyl methacrylate and 0.50g of styrene are weighed and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into an emulsifier aqueous solution, pre-emulsifying for 40min at a magnetic stirring speed of 450rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and carrying out ultrasonic treatment for 8min at a power of 420W in the ice water bath to obtain a stable monomer fine emulsion; adding 0.01g of a water-soluble initiator potassium persulfate to the monomer miniemulsion; and after nitrogen is introduced to remove oxygen, adjusting the reaction temperature to 70 ℃, and reacting for 5 hours under the protection of nitrogen to prepare the FPNPs emulsion with the dynamic fluorescence characteristic.

The Z-average particle size of the FPNPs emulsion is 176nm measured by a dynamic light scattering nanometer particle size analyzer. Under the irradiation of 365nm ultraviolet light, the emulsion gradually changes from initial blue fluorescence to pink purple, and when the irradiation time reaches 13min, the fluorescence color of the emulsion is stable. The characteristic absorption peak of MC-3 in the corresponding ultraviolet-visible light absorption spectrum of the emulsion becomes stronger with the prolonging of the ultraviolet irradiation time. The characteristic fluorescence emission peak of AIE-6 in the corresponding fluorescence spectrum of the emulsion is weaker and weaker along with the extension of the ultraviolet irradiation time, and the characteristic fluorescence emission peak of MC-3 is stronger and stronger.

The obtained emulsion was concentrated to a solid content of 30 wt%, about 350mg of the emulsion was applied to a 7cm × 10cm PET film (polyethylene terephthalate) by knife coating, and baked at 70 ℃ for 3 hours to obtain a coating of FPNPs having dynamic fluorescence characteristics. The FPNPs coating with dynamic fluorescence characteristics gradually changes from initial blue fluorescence to pink purple under continuous ultraviolet lamp irradiation.

Example 5:

0.02g of sodium dodecyl sulfate and 0.005g of Tween-60 were weighed and dissolved in 12.5g of water to obtain an aqueous emulsifier solution. Then 0.003g of AIE-7, 0.006g of SP-8, 0.50g of methyl methacrylate, 0.10g of methyl acrylate, 0.40g of n-hexyl methacrylate and 0.09g of n-hexadecane are weighed in sequence and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into an emulsifier aqueous solution, pre-emulsifying for 22min at a magnetic stirring speed of 750rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and carrying out ultrasonic treatment for 22min under the power of 250W in the ice water bath to obtain a stable monomer fine emulsion; adding 0.01g of water-soluble initiator potassium persulfate and 0.01g of sodium ascorbate into the monomer miniemulsion; and after nitrogen is introduced to remove oxygen, adjusting the reaction temperature to 40 ℃, and reacting for 4 hours under the protection of nitrogen to prepare the FPNPs emulsion with the dynamic fluorescence characteristic.

The Z-average particle size of the FPNPs emulsion is 170nm measured by a dynamic light scattering nanometer particle size analyzer. Under the irradiation of 365nm ultraviolet light, the emulsion gradually changes from initial blue fluorescence to pink, and when the irradiation time reaches 15min, the fluorescence color of the emulsion is stable. The characteristic absorption peak of MC-8 in the corresponding ultraviolet-visible light absorption spectrum of the emulsion becomes stronger with the prolonging of the ultraviolet irradiation time. The characteristic fluorescence emission peak of AIE-7 in the corresponding fluorescence spectrum of the emulsion becomes weaker and weaker along with the extension of the ultraviolet irradiation time, and the characteristic fluorescence emission peak of MC-8 becomes stronger and stronger.

The prepared emulsion is diluted to have the solid content of 5 wt%, is coated on a silicon wafer with the thickness of 0.5cm multiplied by 0.5cm in a dip coating mode, and is dried for 10 hours at the temperature of 50 ℃, so that the weight of the silicon wafer is increased by 0.09 mg. The FPNPs with dynamic fluorescence characteristics are prepared into coatings. The FPNPs coating with dynamic fluorescence properties is gradually changed from initially blue fluorescence to pink under continuous uv lamp illumination.

Example 6:

0.06g of sodium lauryl sulfate and 0.04g of OP-20 were weighed out and dissolved in 12.5g of water to obtain an aqueous emulsifier solution. Then 0.004g of AIE-8, 0.01g of SP-2, 0.30g of methyl methacrylate, 0.20g of styrene, 0.50g of lauryl methacrylate, 0.072g of n-hexadecane and 0.025g of azodiisovaleronitrile are weighed and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into an emulsifier aqueous solution, pre-emulsifying for 15min at a magnetic stirring speed of 900rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and carrying out ultrasonic treatment for 9min at a power of 420W in the ice water bath to obtain a stable monomer fine emulsion; and after nitrogen is introduced to remove oxygen, adjusting the reaction temperature to 60 ℃, and reacting for 10 hours under the protection of nitrogen to obtain the FPNPs emulsion with the dynamic fluorescence characteristic.

The Z-average particle size of the FPNPs emulsion is 77nm measured by a dynamic light scattering nanometer particle size analyzer. Under the irradiation of 365nm ultraviolet light, the emulsion gradually changes from initial blue fluorescence to pink, and when the irradiation time reaches 15min, the fluorescence color of the emulsion is stable. The characteristic absorption peak of MC-2 in the corresponding ultraviolet-visible light absorption spectrum of the emulsion becomes stronger with the prolonging of the ultraviolet irradiation time. The characteristic fluorescence emission peak of AIE-8 in the corresponding fluorescence spectrum of the emulsion is weaker and weaker along with the extension of the ultraviolet irradiation time, and the characteristic fluorescence emission peak of MC-2 is stronger and stronger.

The emulsion is concentrated to a solid content of 30 wt%, about 110mg of the emulsion is coated on a 2cm × 4cm steel material in a blade coating mode, and the coating of FPNPs with dynamic fluorescence characteristics is prepared after the coating is baked for 20 hours at the temperature of 40 ℃. The FPNPs coating with dynamic fluorescence properties is gradually changed from initially blue fluorescence to pink under continuous uv lamp illumination.

Example 7:

0.06g of sodium lauryl sulfate was weighed out and dissolved in 12.5g of water to obtain an aqueous emulsifier solution. Then 0.004g of AIE-4, 0.01g of SP-2, 0.75g of methyl methacrylate, 0.05g N-hydroxyethyl acrylamide and 0.09g of n-hexadecane are weighed in sequence and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into the emulsifier aqueous solution, pre-emulsifying for 30min at a magnetic stirring speed of 500rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and carrying out ultrasonic treatment for 5min at a power of 450W in the ice water bath to obtain a stable monomer fine emulsion; adding 0.01g of water-soluble initiator azobiscyanovaleric acid to the monomer miniemulsion; and after nitrogen is introduced to remove oxygen, adjusting the reaction temperature to 70 ℃, and reacting for 5 hours under the protection of nitrogen to prepare the FPNPs emulsion with the dynamic fluorescence characteristic.

The Z-average particle size of the FPNPs emulsion is 117nm measured by a dynamic light scattering nanometer particle sizer. Under the irradiation of 365nm ultraviolet light, the emulsion gradually changes from the initial blue fluorescence to pink purple, and when the irradiation time reaches 25min, the fluorescence color of the emulsion is stable. The characteristic absorption peak of MC-2 in the corresponding ultraviolet-visible light absorption spectrum of the emulsion becomes stronger with the prolonging of the ultraviolet irradiation time. The characteristic fluorescence emission peak of AIE-4 in the corresponding fluorescence spectrum of the emulsion is weaker and weaker along with the extension of the ultraviolet irradiation time, and the characteristic fluorescence emission peak of MC-2 is stronger and stronger.

The prepared emulsion is diluted to have a solid content of 5 wt%, 8mg of the emulsion is coated on a silicon wafer of 2cm multiplied by 2cm in a spraying manner, and the silicon wafer is dried for 8 hours at the temperature of 60 ℃. The FPNPs with dynamic fluorescence characteristics are prepared into coatings. The FPNPs coating with dynamic fluorescence characteristics gradually changes from initial blue fluorescence to pink purple under continuous ultraviolet lamp irradiation.

Example 8:

0.08g of dodecyl dimethyl hydroxypropyl sulfobetaine and 0.04g of OP-20 were weighed out and dissolved in 12.5g of water to obtain an aqueous emulsifier solution. Then 0.004g of AIE-8, 0.02g of SP-1, 0.70g of methyl methacrylate, 0.10g of ethyl acrylate, 0.10g of octadecyl methacrylate and 0.10g of vinyl acetate are weighed in sequence and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into the emulsifier aqueous solution, pre-emulsifying for 5min at a magnetic stirring speed of 1000rpm to obtain a coarse emulsion, placing a container containing the coarse emulsion in an ice water bath, and performing ultrasonic treatment for 25min at 200W in the ice water bath to obtain a stable monomer fine emulsion; adding 0.015g of water-soluble initiator ammonium persulfate into the monomer miniemulsion; and after nitrogen is introduced to remove oxygen, adjusting the reaction temperature to 70 ℃, and reacting for 5 hours under the protection of nitrogen to prepare the FPNPs emulsion with the dynamic fluorescence characteristic.

The Z-average particle size of the FPNPs emulsion is 82nm measured by a dynamic light scattering nanometer particle size analyzer. Under the irradiation of 365nm ultraviolet light, the emulsion gradually changes from initial blue fluorescence to orange red, and when the irradiation time reaches 18min, the fluorescence color of the emulsion is stable. The characteristic absorption peak of MC-1 in the corresponding ultraviolet-visible light absorption spectrum of the emulsion becomes stronger with the prolonging of the ultraviolet irradiation time. The characteristic fluorescence emission peak of AIE-8 in the corresponding fluorescence spectrum of the emulsion is weaker and weaker along with the extension of the ultraviolet irradiation time, and the characteristic fluorescence emission peak of MC-1 is stronger and stronger.

The prepared emulsion is diluted to have a solid content of 5 wt%, about 1.5mg of the emulsion is coated on a PI film (polyimide film) of 1cm multiplied by 1cm in a spraying manner, and the coating of FPNPs with dynamic fluorescence characteristics is prepared after the coating is baked for 25min at the temperature of 90 ℃. The FPNPs coating with dynamic fluorescence properties was gradually changed from initially blue fluorescence to orange under continuous uv lamp illumination.

Example 9:

0.125g of sodium lauryl sulfate was weighed out and dissolved in 12.5g of water to obtain an aqueous emulsifier solution. Then 0.005g of AIE-8, 0.01g of SP-2, 0.75g of methyl methacrylate, 0.05g of butyl acrylate, 0.05g of isooctyl acrylate, 0.15g of octadecyl methacrylate and 0.025g of azobisisobutyronitrile are weighed in sequence and mutually dissolved to obtain an oil phase solution. Adding the oil phase solution into an emulsifier aqueous solution, pre-emulsifying for 40min at a magnetic stirring speed of 450rpm to obtain a coarse emulsion, placing a container filled with the coarse emulsion in an ice water bath, and carrying out ultrasonic treatment for 8min at a power of 420W in the ice water bath to obtain a stable monomer fine emulsion; and after nitrogen is introduced to remove oxygen, adjusting the reaction temperature to 70 ℃, and reacting for 5 hours under the protection of nitrogen to prepare the FPNPs emulsion with the dynamic fluorescence characteristic.

The Z-average particle size of the FPNPs emulsion is 53nm measured by a dynamic light scattering nanometer particle size analyzer. Under the irradiation of 365nm ultraviolet light, the emulsion gradually changes from initial blue fluorescence to orange red, and when the irradiation time reaches 16min, the fluorescence color of the emulsion is stable. The characteristic absorption peak of MC-2 in the corresponding ultraviolet-visible light absorption spectrum of the emulsion becomes stronger with the prolonging of the ultraviolet irradiation time. The characteristic fluorescence emission peak of AIE-8 in the corresponding fluorescence spectrum of the emulsion is weaker and weaker along with the extension of the ultraviolet irradiation time, and the characteristic fluorescence emission peak of MC-2 is stronger and stronger.

Diluting the prepared emulsion to the solid content of 5 wt%, taking about 300mg of the emulsion, coating the emulsion on a 4cm multiplied by 4cm steel material in a spraying mode, and baking the emulsion for 10 hours at the temperature of 50 ℃ to obtain a FPNPs coating with dynamic fluorescence characteristics. The FPNPs coating with dynamic fluorescence properties was gradually changed from initially blue fluorescence to orange under continuous uv lamp illumination.

The above-described embodiments of the invention are intended to be illustrative of the invention and are not to be construed as limiting the invention, and any variations that fall within the meaning and scope of the invention equivalent to the claims are intended to be embraced therein.