CN110835530A - Reversible light modulation and control fluorescent liquid crystal nano particle and reversible light modulation and control color fluorescent ink - Google Patents

Abstract

The invention discloses a reversible light-adjustable fluorescent liquid crystal nanoparticle and a reversible light-adjustable color fluorescent ink. The reversible light-adjustable fluorescent liquid crystal nanoparticle is prepared by a mini-emulsion polymerization method. The monomer, the nematic liquid crystal monomer and the diarylethene compound are evenly mixed to obtain a liquid crystal mixture; the thermal initiator, the stabilizer and the liquid crystal mixture are mixed to obtain an oil phase, and the emulsifier and water are mixed to obtain a water phase, The oil phase and the water phase are mixed and emulsified to obtain a coarse emulsion; the coarse emulsion is ultrasonically homogenized to obtain a fine emulsion; in the presence of a protective gas, the small emulsion is deoxygenated and then heated and polymerized to obtain a reversible light-regulated fluorescent liquid crystal nanoparticle. particle; wherein, the cyanostilbene structural monomer is shown in general formula I, M ₁ is a group represented by R ₁ , R ₂ , R ₃ or R ₄ , and M ₂ is selected from general formula II or general formula III. group, n is an integer of 1-9;

Description

Reversible light-tunable fluorescent liquid crystal nanoparticles and reversible light-tunable color fluorescent ink

technical field

The invention belongs to the field of liquid crystal nanoparticle materials, and more particularly relates to a reversible light-regulated fluorescent liquid crystal nanoparticle and a reversible light-regulated color fluorescent ink.

Background technique

Liquid crystal is an intermediate phase between liquid and crystal. Usually, the liquid crystal molecular structure is slender and has a certain rigidity, which makes the arrangement of the liquid crystal molecules have a certain direction, so that the liquid crystal has both the fluidity and the liquid crystal. Continuity and order and anisotropy of crystals. Because of the unique structure and characteristics, the liquid crystal material has unique optical properties, and the arrangement of the liquid crystal molecules is easily changed by the action of external stimuli.

Under specific process conditions, the liquid crystal material is prepared into liquid crystal particles with a particle size of less than or equal to 100 nm, which are called liquid crystal nanoparticles (LCNPs). It has the characteristics of (1) easy preparation, monodisperse nano-microsphere structure that can reach 100nm or even smaller particle size (2) low toxicity (3) good stability (4) easy to be observed under specific conditions and so on. Based on the above characteristics, liquid crystal nanoparticles are expected to be used in the delivery of drugs in vivo, as well as the storage, reproduction and visualization of information.

Fluorescent materials can be widely used in all aspects of production and life. For example, in agriculture, agricultural light conversion films can be prepared to convert the ultraviolet light that is not conducive to the growth of crops into red-orange light suitable for their growth, which can increase the yield; In industry, it can be used in anti-counterfeiting printing, and the color can be changed under external light stimulation; in medical treatment, it can be used as a fluorescent label for biomolecules, and then used for drug delivery. However, traditional organic fluorescent materials [1] have the disadvantages of short fluorescence lifetime, easy photolysis, easy fading, and most of the photolysis products are toxic and harmful, which limits their application. The organic fluorescent material of cyanostilbene structure is an organic material containing a conjugated structure, which has the advantages of strong fluorescence ability, easy modification of structure, easy adjustment of photofunctional properties, low toxicity and environmental protection, and stable fluorescence, avoiding some linear organic conjugated fluorescence. The presence of fluorescence quenching effect (aggregation-caused quenching, ACQ) of the material. The stilbene derivatives containing cyano group substitution are called cyanostilbene structure or cyanostilbene structure derivatives, which have a kind of aggregation induced enhanced emission (AIEE), usually due to the intermolecular structure. The presence of strong interactions results in substantial nonradiative inactivation, and the fluorescence intensity of fluorescent organic compounds is much higher in dilute solution than in the solid or aggregated state, while aggregation-induced enhanced emission (AIEE) compounds are the exact opposite. Their derivatives have very high fluorescence quantum yields in the solid or aggregated state.

In 1988, Zhenghao Irie and others designed and synthesized diarylethene compounds with photoisomerization reaction on the basis of stilbene. This is a class of compounds that have photoisomerization reactions. This compound will undergo ring opening and closing reactions under light conditions, resulting in the conversion of isomers, during which intramolecular or intermolecular energy resonance transfer occurs. The emission and other aspects are different, and the molecule maintains good stability whether in the open-loop or closed-loop state. It has the following advantages: 1. Good thermal stability; 2. Strong anti-fatigue performance, and the number of molecular open and closed loop cycles is very high; 3. Fast light response behavior, and the molecular response to light can occur within 2-20ps; ④ Open and closed loops The conversion rate is high, and most of its open-loop/closed-loop conversion rates under the action of light can reach 100%.

Therefore, it is necessary to provide a fluorescent liquid crystal nanoparticle.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a fluorescent liquid crystal nanoparticle, and further provide a color fluorescent ink that can be reversibly light-regulated with 365nm ultraviolet-visible light.

In order to achieve the above object, one aspect of the present invention provides a reversible light-regulated fluorescent liquid crystal nanoparticle, which is prepared by a mini-emulsion polymerization method, and specifically includes the following steps:

(1) in the presence of the first organic solvent, uniformly mixing the cyanostilbene structural monomer, the nematic liquid crystal monomer and the diarylethene compound to obtain a liquid crystal mixture;

(2) mixing thermal initiator, stabilizer and described liquid crystal mixture to obtain oil phase, mixing emulsifier and water to obtain water phase, mixing and emulsification of oil phase and water phase to obtain coarse emulsion;

(3) ultrasonically homogenizing the coarse emulsion to obtain a fine emulsion;

(4) in the presence of protective gas, heating and polymerizing the mini-emulsion to obtain liquid crystal nanoparticles;

Wherein, the cyanostilbene structural monomer is shown in general formula I, M ₁ is a group represented by R ₁ , R ₂ , R ₃ or R ₄ , and M ₂ is selected from general formula II or general formula III. group, n is an integer of 1-9;

Another aspect of the present invention provides a reversible light-adjustable color fluorescent ink. Based on the total weight of the reversible light-adjustable color fluorescent ink, the reversible light-adjustable color fluorescent ink comprises: 3-10wt% of the above reversible light-adjustable fluorescent ink Liquid crystal nanoparticles, 2-6wt% film-forming agent, 5-45wt% water-soluble organic solvent, 2-4wt% emulsifier, 0.1-2wt% pH adjuster and 0-70wt% water, and each group The sum of the fractions is 100 wt%.

The technical scheme of the present invention has the following advantages:

The invention provides a new type of polymerizable cyanostilbene structural monomer, which can obtain red, blue and green fluorescence respectively under the excitation of ultraviolet light;

The fluorescent liquid crystal nanoparticles of the present invention can perform reversible regulation of fluorescence intensity under the alternating irradiation of ultraviolet light and visible light;

The fluorescent liquid crystal nanoparticles of the present invention can be prepared to obtain color fluorescent ink, and after inkjet printing, the fluorescent image of the written information can be reversibly changed from hidden to obvious.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Description of drawings

The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of the exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the exemplary embodiments of the present invention. same parts.

FIG. 1 shows a scanning electron microscope photograph of a reversible light-adjustable fluorescent liquid crystal nanoparticle according to an embodiment of the present invention.

Fig. 2a shows a schematic diagram of the fluorescence emission spectrum of the reversible light-tunable fluorescent liquid crystal nanoparticles according to an embodiment of the present invention under the irradiation of a UV lamp with a power of 2 mW and a wavelength of 365 nm. Among them, the curves from top to bottom in the figure represent the fluorescence emission spectra at 0s, 5s, 10s, 15s, 20s, 25s, and 30s, respectively.

Fig. 2b shows a schematic diagram of the time-dependent change of the fluorescence emission spectrum of the reversible light-adjustable fluorescent liquid crystal nanoparticles under the illumination of a visible light source according to an embodiment of the present invention. The curves from bottom to top in the figure represent the fluorescence emission spectra at 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, and 110s, respectively.

FIG. 3 is a schematic diagram showing the change of the limit value of the fluorescence intensity with time of the reversible light-tunable fluorescent liquid crystal nanoparticles under the alternating irradiation of ultraviolet-visible light sources according to an embodiment of the present invention.

FIG. 4 shows the actual graph of the fluorescence intensity change of the pattern printed on the printing paper by the inkjet printing technology of the reversible light-adjustable color fluorescent ink according to an embodiment of the present invention under the alternating irradiation of ultraviolet-visible light.

Detailed ways

Preferred embodiments of the present invention will be described in more detail below. While the preferred embodiments of the present invention are described below, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

One aspect of the present invention provides a reversible light-adjustable fluorescent liquid crystal nanoparticle, the reversible light-adjustable fluorescent liquid crystal nanoparticle is prepared by a mini-emulsion polymerization method, and specifically includes the following steps:

(1) in the presence of the first organic solvent, uniformly mixing the cyanostilbene structural monomer, the nematic liquid crystal monomer and the diarylethene compound to obtain a liquid crystal mixture;

(2) mixing thermal initiator, stabilizer and described liquid crystal mixture to obtain oil phase, mixing emulsifier and water to obtain water phase, mixing and emulsification of oil phase and water phase to obtain coarse emulsion;

(3) ultrasonically homogenizing the coarse emulsion to obtain a fine emulsion;

(4) in the presence of protective gas, heating and polymerizing the mini-emulsion to obtain liquid crystal nanoparticles;

Wherein, the cyanostilbene structural monomer is shown in general formula I, M ₁ is a group represented by R ₁ , R ₂ , R ₃ or R ₄ , and M ₂ is selected from general formula II or general formula III. group, n is an integer of 1-9;

In the present invention, the reversible light-regulated fluorescent liquid crystal nanoparticles are prepared by a mini-emulsion polymerization method, and the composition of the cyanostilbene structural monomer, the diarylene compound and the nematic liquid crystal monomer is encapsulated in the nanoparticles.

In the present invention, the fluorescence band of the cyanostilbene structural monomer can be changed by the change of its own molecular conjugated structure and aggregation state, and the cyanostilbene monomers with different fluorescent colors can be obtained macroscopically through molecular structure design.

In the present invention, the diarylethene compound is introduced into the fluorescent liquid crystal nanoparticle system, and the compound will undergo a ring-opening and closing reaction under illumination conditions, which can be achieved by the energy resonance transfer effect (FRET) with the cyanostilbene structural monomer. The reversible regulation of fluorescence can be used as a fluorescent molecular switch to realize the reversible light regulation of fluorescent liquid crystal nanoparticles, that is, through the alternating irradiation of UV-Vis light (ultraviolet-visible light), the diarylethene compounds undergo a ring-opening and ring-closing reaction, and the Cyanostilbene structural monomer undergoes energy resonance transfer, resulting in a reversible change in fluorescence with and without it.

According to the present invention, preferably, the cyanostilbene structural monomer is selected from one of the cyanostilbene structural compounds having the structures represented by the general formulas a-1, a-2, a-3, a-4, and a-5 or more, wherein, n is an integer of 1-9;

According to the present invention, preferably, the preparation method of the cyanostilbene structural monomer is selected from the first preparation method, the second preparation method or the third preparation method;

Wherein, the first preparation method comprises the following steps:

(1) in the presence of the second organic solvent, the first basic regulator and the first catalyst, the compound I and the compound II are subjected to a contact reaction to obtain the compound III;

(2) in the presence of the third organic solvent and the second basic regulator, the compound III and the compound IV are subjected to a contact reaction, and the compound V is obtained after the solvent is evaporated;

(3) in the presence of a fourth organic solvent and an acid binding agent, the compound V and acryloyl chloride are subjected to a contact reaction to obtain the cyanostilbene structural monomer;

The second preparation method comprises the following steps:

(1) in the presence of the fifth organic solvent and the third basic regulator, the compound VI and the compound VII are subjected to a contact reaction to obtain the compound VIII;

(2) in the presence of the sixth organic solvent and the second catalyst, the compound VIII and DMF are subjected to a contact reaction to obtain compound IX;

(3) in the presence of the seventh organic solvent, the compound X is contacted and reacted with NBS to obtain compound XI;

(4) in the presence of the eighth organic solvent, the ninth organic solvent, the third catalyst and the Na2CO3 aqueous solution, the compound XI and the compound XII are subjected to a contact reaction to obtain the compound XIII;

(5) in the presence of the second organic solvent, the first basic regulator and the first catalyst, the compound XIII and the compound II are subjected to a contact reaction to obtain the compound XIV;

(6) in the presence of the third organic solvent and the second basic regulator, the compound XIV and the compound IX are subjected to a contact reaction, and the compound XV is obtained after the solvent is evaporated;

(7) in the presence of a fourth organic solvent and an acid binding agent, the compound XV and acryloyl chloride are subjected to a contact reaction to obtain the cyanostilbene structural monomer;

The third preparation method comprises the following steps:

(1) in the presence of the seventh organic solvent, the compound X is contacted and reacted with NBS to obtain compound XI;

(2) in the presence of the eighth organic solvent, the ninth organic solvent, the third catalyst and the Na ₂ CO ₃ aqueous solution, the compound XI and the compound XII are subjected to a contact reaction to obtain the compound XIII;

(3) in the presence of the second organic solvent, the first basic regulator and the first catalyst, the compound XIII and the compound II are subjected to a contact reaction to obtain the compound XIV;

(4) in the presence of the third organic solvent and the second basic regulator, the compound XIV and the compound IV are subjected to a contact reaction, and the compound XVI is obtained after the solvent is evaporated;

(5) in the presence of a fourth organic solvent and an acid binding agent, the compound XVI and acryloyl chloride are subjected to a contact reaction to obtain the cyanostilbene structural monomer;

The structural formula of the compound I is:

The structural formula of the compound II is:

式中，n为1-9的整数，X选自溴原子或碘原子；

In the formula, n is an integer of 1-9, and X is selected from a bromine atom or an iodine atom;

The structural formula of the compound III is

In the formula, n is an integer from 1 to 9;

The structural formula of the compound IV is:

其中，R选自所述R₁、R₂、R₃或R₄所示的结构基团，

wherein, R is selected from the structural groups represented by the R ₁ , R ₂ , R ₃ or R ₄ ,

The structural formula of the compound V is:

In the formula, n is an integer of 1-9; the structural formula of the compound VI is:

The structural formula of the compound VII is:

The structural formula of the compound VIII is:

The structural formula of the compound IX is:

The structural formula of the compound X is:

The structural formula of the compound XI is:

The structural formula of the compound XII is:

The structural formula of the compound XIII is:

式中，n为1-9的整数；The structural formula of the compound XIV is:

In the formula, n is an integer from 1 to 9;

The structural formula of the compound XV is:

式中，n为1-9的整数。

In the formula, n is an integer of 1-9.

The structural formula of the compound XVI is:

式中，n为1-9的整数。

In the formula, n is an integer of 1-9.

According to the present invention, preferably,

The reaction conditions of each step in the first preparation method include the following:

In step (1): the first alkaline regulator is anhydrous potassium carbonate, and the first catalyst is potassium iodide; the mol ratio of the compound I, compound II, anhydrous potassium carbonate and potassium iodide is 1:3- 10:3-10:0.1-1, the second organic solvent is a polar organic solvent, the second organic solvent is preferably at least one of dimethylformamide, acetonitrile, tetrahydrofuran and acetone, more preferably Acetone; the temperature of the contact reaction is 30-80 °C, and the time is 12-24 h; as a preferred solution, after the reaction is completed, the compound can be obtained by washing with water, separating liquids, evaporating the organic phase solvent, and then purifying by column chromatography III;

In step (2): the second alkaline regulator is potassium tert-butoxide; the molar ratio of compound III, compound IV and potassium tert-butoxide is 2-3:1:0.1-0.5, and the contact reaction The temperature is 30-80°C, and the time is 2-8h; as a preferred solution, after the reaction is completed, add hydrochloric acid for neutralization to make the system acidic, suction filtration, cleaning, and drying to obtain compound V; Three organic solvents are ethanol;

In step (3): the acid binding agent is triethylamine; the molar ratio of the compound V, acryloyl chloride and triethylamine is 1:3-4:3-5, and the temperature of the contact reaction is 0- 40 ℃, time is 12-24h; as a preferred solution, after the reaction is completed, add water to quench the reaction, separate and dry, evaporate the organic phase solvent, and then purify by column chromatography to obtain the cyanostilbene structural monomer; the The fourth organic solvent is chloroform;

The reaction conditions of each step in the second preparation method include the following:

In step (1): the third alkaline regulator is NaH or NaOH; the molar ratio of the compound VI, the compound VII and the third alkaline regulator is 1:1-3:1-10, so the The temperature of the contact reaction is 0-40 ° C, and the time is 1-2 hours; as a preferred solution, the fifth organic solvent is dimethyl sulfoxide; The organic phase solvent is then purified by column chromatography to obtain compound VIII;

In step (2): the molar ratio of the compound VIII, DMF and the second catalyst is 1:2-5:0.1-1, the first catalyst is POCl , the temperature of the contact reaction is 30-70 ° C, and the time It is 12-24h; as a preferred solution, after the reaction is completed, compound IX can be obtained by washing with water, separating liquids, evaporating the organic phase solvent, and purifying by column chromatography; the sixth organic solvent is dichloromethane;

In step (3): the molar ratio of the compound X to NBS is 1:1-3, the temperature of the contact reaction is 0-40°C, and the time is 1-5h; preferably, the seventh organic solvent is N,N-dimethylformamide;

In step (4): the molar ratio of the compound XI, the compound XII and the second catalyst is 1:1-3:0.1-1, and the mass fraction of the Na2CO3 aqueous solution is 10-30%; The second catalyst is preferably tetrakistriphenylphosphine palladium; preferably, the eighth organic solvent is tetrahydrofuran, and the ninth organic solvent is methanol;

Step (5) includes: the first alkaline regulator is anhydrous potassium carbonate, and the first catalyst is potassium iodide; the mol ratio of compound XIII, compound II, anhydrous potassium carbonate and potassium iodide is 1:3-10: 3-10: 0.1-1, the second organic solvent is a polar organic solvent, preferably at least one of dimethylformamide, acetonitrile, tetrahydrofuran and acetone, more preferably acetone; the temperature of the contact reaction The temperature is 30-80°C, and the time is 12-24h; as a preferred solution, after the reaction is completed, compound XIV can be obtained by washing with water, separating liquids, evaporating the organic phase solvent, and purifying by column chromatography;

Step (6) includes: the second alkaline regulator is potassium tert-butoxide; the molar ratio of compound XIV, compound IX and potassium tert-butoxide is 2-4:1:0.2-1, and the contact reaction is 2-4:1:0.2-1. The temperature is 30-80°C, and the time is 2-8 hours; as a preferred solution, after the reaction is completed, add hydrochloric acid for neutralization to make the system acidic, suction filtration, cleaning and drying to obtain compound XV; the third organic The solvent is ethanol;

Step (7) includes: the third alkaline regulator is triethylamine; the molar ratio of the compound XV, acryloyl chloride and triethylamine is 1:3-4:3-5, and the temperature of the contact reaction is 0-40℃, the time is 12-24h. As a preferred solution, after the reaction is completed, add water to quench the reaction, separate and dry the organic phase solvent, and then purify the cyanostilbene structural monomer by column chromatography; the fourth organic solvent is chloroform;

The reaction conditions of each step in the third preparation method include the following:

In step (1): the molar ratio of the compound X to NBS is 1:1-3, the temperature of the contact reaction is 0-40°C, and the time is 1-5h;

In step (2): the molar ratio of the compound XI, the compound XII and the second catalyst is 1:1-3:0.1-1, and the mass fraction of the Na ₂ CO ₃ aqueous solution is 10-30%;

In step (3): the first alkaline regulator is anhydrous potassium carbonate, the first catalyst is potassium iodide, and the mol ratio of the compound XIII, compound II, anhydrous potassium carbonate and potassium iodide is 1:3- 10:3-10:0.1-1, the second organic solvent is a polar organic solvent, the temperature of the contact reaction is 30-80°C, and the time is 12-24h;

In step (4): the second alkaline regulator is potassium tert-butoxide; the molar ratio of compound XIV, compound IV and potassium tert-butoxide is 2-4:1:0.2-1, and the contact reaction The temperature is 30-80℃, and the time is 2-8h;

In step (5): the acid binding agent is triethylamine; the molar ratio of the compound XVII to acryloyl chloride is 1:3-4:3-5, the temperature of the contact reaction is 0-40°C, and the time 12-24h.

According to the present invention, preferably, the diarylethene compound has the structure shown in the general formula IV, and is an open or closed ring structure; wherein, X ₁ and X ₂ are each independently selected from R ₅ , R ₆ , In the structural group represented by R ₇ , R ₈ , R ₉ or R ₁₀ , X ₁ and X ₂ are the same or different;

According to the present invention, preferably, the diarylethene compound is selected from one of the diarylethene compounds having the structures represented by the general formulas b-1, b-2, b-3, b-4, and b-5. one or more; and the following general structures are open-loop or closed-loop structures.

According to the present invention, preferably, the nematic liquid crystal monomer is at least one of C4M, C6M and C8M.

According to the present invention, preferably, in the preparation method of reversible light-regulated fluorescent liquid crystal nanoparticles: in step (1): the mass ratio of the nematic liquid crystal monomer to the cyanostilbene structural monomer is 70-200:1; The mass ratio of the diarylethene compound to the cyanostilbene structural monomer is 1-9:1; the first organic solvent is dichloromethane and/or chloroform, and the mass ratio of the first organic solvent to the nematic liquid crystal monomer is The ratio is 2-10:1;

In step (2): based on the total weight of the mixture of the cyanostilbene structural monomer and the nematic liquid crystal monomer, the content of the thermal initiator is 0.1-2 wt %, and the content of the stabilizer is 1-2 wt %. 10wt%, the added amount of the emulsifier is 10-20wt%; the volume ratio of water to the first organic solvent is 30-50:1, and the emulsifier is sodium dodecyl sulfate (SDS) or 11- (Acryloyloxy) sodium undecanoate (AC ₁₀ COONa), the thermal initiators are azobisisobutyronitrile (AIBN), azobisisovaleronitrile (AMBN) and benzoyl peroxide (BPO) In at least one, the stabilizer is at least one of cetyl alcohol (CA), n-hexadecane (HD), stearyl methacrylate (SMA) and stearyl acrylate (SA), The emulsification time is 1-6h;

In step (3): the power of the ultrasonic homogenization is 120-450W, and the time is 5-30min;

In step (4): the temperature of the heating polymerization is 60-80° C., and the time is 12-24 h.

Another aspect of the present invention provides a reversible light-adjustable color fluorescent ink. Based on the total weight of the reversible light-adjustable color fluorescent ink, the reversible light-adjustable color fluorescent ink comprises: 3-10wt% of the above reversible light-adjustable fluorescent ink Liquid crystal nanoparticles, 2-6wt% film-forming agent, 5-45wt% water-soluble organic solvent, 2-4wt% emulsifier, 0.1-2wt% pH adjuster and 0-70wt% water, and each group The sum of the fractions is 100 wt%.

The reversible light-regulated color fluorescent ink of the present invention can write information on paper by an inkjet printing method, and can realize the change of the fluorescent image of the written information from hidden to obvious by alternately irradiating UV-Vis light, so as to print the text content of the document. It provides important reference value for the application in the field of reproduction, identification and visualization of information.

According to the present invention, preferably, the film-forming agent is at least one of polyvinyl alcohol, water-based polyurethane, polyethylene glycol, chitosan and gelatin; the water-soluble organic solvent is ethylene glycol, glycerol , at least one of diethylene glycol monomethyl ether, propylene glycol methyl ether and dipropylene glycol dimethyl ether; the pH regulator is at least one of ammonia water, NaHCO ₃ , Na ₂ CO ₃ and triethanolamine; the The emulsifier is at least one of sodium dodecyl sulfate (SDS), 11-(acryloyloxy) sodium undecanoate (AC ₁₀ COONa) and polyvinyl alcohol (PVA).

The present invention is further illustrated below by embodiment:

1. Preparation of cyanostilbene structural monomer:

Preparation Example 1

(1) Take 3 g of p-hydroxyphenylacetonitrile and 4.08 g of 6-bromohexanol for feeding, then add 6.23 g of anhydrous potassium carbonate and 0.56 g of potassium iodide, and stir and reflux in acetone at 60°C for 12 h. After finishing, carry out suction filtration under reduced pressure, remove the filter residue, concentrate the filtrate by rotary evaporation, and then use the mixed solution prepared in the volume ratio of chloroform:ethyl acetate=3:1 as a solvent to carry out chromatographic column separation to obtain compound III;

(2) 6.9 g of compound III and 1.24 g of 2,5-dialdehyde furan were added to ethanol and stirred, and after dissolving, 0.22 g equivalent of potassium tert-butoxide was added to make the system strongly basic, stirred at 70° C. and refluxed for 4 h, then Add about 1ml of hydrochloric acid for neutralization to make the system acidic, filter under reduced pressure, and wash the filter residue with ethanol, and place the filter residue in a vacuum oven for drying to obtain compound V;

(3) 5.5g of compound V, 2.7g of acryloyl chloride and 4.4g of triethylamine were added to chloroform, then moved to normal temperature and stirred for 12h, after the reaction was completed, 50ml of water was added to quench the reaction, and the liquid was separated with a separating funnel , remove the organic phase of the lower layer, add anhydrous sodium sulfate for drying, let stand in the dark for 12 hours, and concentrate the organic phase by rotary evaporation. Column separation to obtain the cyanostilbene structural monomer of the structure shown in compound 1 in Table 1.

Preparation Example 2

(1) The initial mass of compound I was 3 g, 4.08 g of 6-bromohexanol was charged, 6.23 g of anhydrous potassium carbonate and 0.56 g of potassium iodide were added, and the mixture was stirred and refluxed in acetone at 60°C for 12 h. After the reaction is finished, carry out suction filtration under reduced pressure, remove the filter residue, and concentrate the filtrate by rotary evaporation, and then use the mixed solution prepared in the volume ratio of chloroform:ethyl acetate=3:1 as a solvent to carry out chromatographic column separation to obtain compound III;

(2) 6.9 g of compound III and 1.3 g of terephthalaldehyde were added to ethanol and stirred, and after dissolving, 0.22 g equivalent of potassium tert-butoxide was added to make the system strongly alkaline, stirred at 70° C. and refluxed for 4 h, and then added about 1 ml The hydrochloric acid is neutralized to make the system acidic, vacuum filtration is performed, and the filter residue is washed with ethanol, and the filter residue is placed in a vacuum oven for drying to obtain compound V, wherein n is 6;

(3) 5.6 g of compound V, 2.7 g of acryloyl chloride and 4.4 g of triethylamine were added to chloroform, then moved to normal temperature and stirred for 12 h. After the reaction was completed, 50 ml of water was added to quench the reaction, and the liquid was separated with a separatory funnel. , remove the organic phase of the lower layer, add anhydrous sodium sulfate for drying, let stand in the dark for 12 hours, and concentrate the organic phase by rotary evaporation. Column separation to obtain the cyanostilbene structural monomer of the structure shown in compound 2 in Table 1.

Preparation Example 3

(1) 2.0 g of compound VI, 1.2 g of 1-bromopropane and 0.24 g of NaH were added to dimethyl sulfoxide, reacted at room temperature for 1 h, concentrated by rotary evaporation after the reaction, and then mixed with chloroform:ethyl acetate=3:1 The mixed solution prepared in the volume ratio is the solvent for chromatographic column separation to obtain compound VIII;

(2) 2.5 g of compound VIII, 2.5 g of anhydrous DMF, and 0.15 g of POCl ₃ were added to dichloromethane, reacted at 50° C. for 12 h, washed with water after the reaction, and the organic phase was concentrated by rotary evaporation, and then mixed with chloroform:ethyl acetate The mixed solution prepared with the volume ratio of ester=3:1 is used as the solvent to carry out chromatographic column separation to obtain compound IX;

(3) 1.23 g of compound X and 1.8 g of NBS were reacted in DMF at room temperature for 3 h, washed with water and extracted with dichloromethane after the reaction, the organic phase was concentrated by rotary evaporation, and the chromatographic column was separated by using dichloromethane as a solvent to obtain the compound Ⅺ;

(4) Compound XI 2g, compound XII 1.4g, tetrakistriphenylphosphine palladium 0.9g were added to the mixed solution of THF, methanol and NaCO ₃ aqueous solution, and reacted at 80°C for 24h. After the reaction was completed, the product was washed with water and washed with ethyl acetate. Extraction, after concentrating, use the mixed solution prepared by the volume ratio of dichloromethane:ethyl acetate=1:2 as solvent to carry out chromatographic column separation to obtain XIII;

(5) Take 2.2 g of compound XIII and 1.8 g of 6-bromohexanol for feeding, then add 2.8 g of anhydrous potassium carbonate and 0.33 g of potassium iodide, and stir and reflux in acetone at 60 °C for 12 h. After finishing, carry out suction filtration under reduced pressure, remove the filter residue, concentrate the filtrate by rotary evaporation, then use the mixed solution prepared in the volume ratio of chloroform:ethyl acetate=3:1 as a solvent to carry out chromatographic column separation to obtain compound XIV;

(6) 6.3 g of compound XIV and 3.0 g of compound IX were added to ethanol and stirred. After dissolving, 0.22 g of potassium tert-butoxide was added to make the system strongly alkaline. The system was stirred and refluxed at 70°C for 4 h, and then about 1 ml of hydrochloric acid was added to carry out the process. and, make the system acidic, filter under reduced pressure, and wash the filter residue with ethanol, and place the filter residue in a vacuum oven for drying to obtain compound XV;

(7) 4.4 g of compound XV, 0.9 g of acryloyl chloride and 1.5 g of triethylamine were added to chloroform, then moved to normal temperature and stirred for 12 h. After the reaction was completed, 50 ml of water was added to quench the reaction, and the liquid was separated with a separatory funnel. , remove the organic phase of the lower layer, add anhydrous sodium sulfate for drying, let stand in the dark for 12 hours, and concentrate the organic phase by rotary evaporation. Column separation to obtain the cyanostilbene structural monomer of the structure shown in compound 3 in Table 1.

Table 1

2. Preparation of reversible light-regulated fluorescent nanoparticles:

Example 1

(1) 0.1 g of C6M, 0.001 g of cyanostilbene structural monomer (compound 1 in Table 1) and 0.005 g of BTE (structure shown in b-3), a total of 0.106 g of raw materials were mixed, and then 300 μl of chloroform was added to make it fully Dissolved to obtain a liquid crystal mixture;

(2) Add 0.0018g thermal initiator AIBN and 0.005g stabilizer stearyl acrylate to the liquid crystal mixture and mix well to obtain an oil phase; add 0.02g emulsifier AC10COONa to 10ml deionized water and mix well to obtain a water phase, while magnetic stirring The oil phase was dropped into the water phase dropwise, and stirred at room temperature for 3 hours to emulsify to obtain a crude emulsion with an oil-in-water structure;

(3) homogenize the crude emulsion in an ultrasonic cell disruptor with a power of 400w ultrasonic for 15min under ice bath conditions to obtain a fine emulsion;

(4) Put the mini-emulsion into a three-necked flask, stir for 15 minutes while condensing through N2 and water to remove oxygen, then heat the aqueous solution in a water bath at 70°C, and stir for 24 hours at a certain stirring speed to obtain a reversible light-regulated fluorescent liquid crystal Nanoparticles.

3. Preparation of reversible light-regulated color fluorescent ink:

Example 2

The present embodiment provides a reversible light-regulated color fluorescent ink, and the specific preparation method is as follows:

(1) drying the green reversible light-regulated fluorescent liquid crystal nanoparticles prepared in Example 1 in a vacuum oven to obtain a dry green fluorescent dye;

(2) weighing 5.0 g of dry green fluorescent dye, 100 g of a polyvinyl alcohol aqueous solution with a mass concentration of 5 wt%, 30 g of glycerol and 3.5 g of AC10COONa and stirred at 3000 r/min with a stirring paddle for 20 min;

(3) 0.8g Na ₂ HCO ₃ was added to adjust the pH value to 8.4 to obtain a reversible light-adjustable color fluorescent ink.

Test Example 1

Electron microscope scanning was performed on the reversible light-regulated fluorescent liquid crystal nanoparticles prepared in Example 1.

As shown in Fig. 1, an obvious spherical structure can be seen, indicating that the composition of the cyanostilbene structural monomer, the diarylene compound and the nematic liquid crystal monomer is encapsulated in the nanoparticles.

Test case 2

The reversible light-regulated fluorescent fluorescent liquid crystal nanoparticles prepared in Example 1 were irradiated under a UV lamp with a power of 2 mW and a wavelength of 365 nm and visible light, and the change in the fluorescence intensity was observed.

As shown in Figure 2a, when the reversible light-regulated fluorescent liquid crystal nanoparticles of the present invention are irradiated by a UV lamp with a power of 2mW and a wavelength of 365nm, the fluorescence intensity is weakened, and reaches a stable value after 30s; Under the irradiation of visible light source, the fluorescence intensity of the backlight-controlled fluorescent liquid crystal nanoparticles recovered and reached a stable value after 110 s.

Test case 3

The reversible light-regulated color fluorescent ink prepared in Example 2 was printed with EPSON-L383 ink tank type to obtain the pattern as shown in Figure 4 (left); the obtained pattern was irradiated under an ultraviolet (UV) lamp with a wavelength of 365nm at 2mW. 30s, the fluorescence intensity is weakened to obtain the pattern as shown in Figure 4 (right); then the pattern is irradiated under visible light for 110s to recover the fluorescence intensity to obtain the pattern as shown in Figure 4 (left); it can be seen that the fluorescence intensity of the fluorescent ink of the present invention can generate Reversible changes, enabling reversible photoregulation.

Various embodiments of the present invention have been described above, and the foregoing descriptions are exemplary, not exhaustive, and not limiting of the disclosed embodiments. Numerous modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims (10)

1. a reversible light-regulated fluorescent liquid crystal nanoparticle, is characterized in that, this reversible light-regulated fluorescent liquid crystal nanoparticle is obtained by miniemulsion polymerization method, specifically comprises the steps: (1) in the presence of the first organic solvent, uniformly mixing the cyanostilbene structural monomer, the nematic liquid crystal monomer and the diarylethene compound to obtain a liquid crystal mixture; (2) mixing the thermal initiator, the stabilizer and the liquid crystal mixture to obtain an oil phase, mixing an emulsifier and water to obtain a water phase, and mixing and emulsifying the oil phase and the water phase to obtain a coarse emulsion; (3) ultrasonically homogenizing the coarse emulsion to obtain a fine emulsion; (4) in the presence of protective gas, deoxygenating the mini-emulsion and then performing heating and polymerization to obtain reversible light-regulated fluorescent liquid crystal nanoparticles; Wherein, the cyanostilbene structural monomer is shown in general formula I, M ₁ is a group represented by R ₁ , R ₂ , R ₃ or R ₄ , and M ₂ is selected from general formula II or general formula III. group, n is an integer of 1-9;

. 2. The reversible light-regulating fluorescent liquid crystal nanoparticle according to claim 1, wherein the cyanostilbene structural monomer is selected from the group consisting of formula a-1, a-2, a-3, a-4, a-5 One or more of the cyanostilbene structure compounds of the structure shown, wherein, n is an integer of 1-9;

3. The reversible light-regulated fluorescent liquid crystal nanoparticle according to claim 1 or 2, wherein the preparation method of the cyanostilbene structural monomer is selected from the first preparation method or the second preparation method; Wherein, the first preparation method comprises the following steps: (1) in the presence of the second organic solvent, the first basic regulator and the first catalyst, the compound I and the compound II are subjected to a contact reaction to obtain the compound III; (2) in the presence of the third organic solvent and the second basic regulator, the compound III and the compound IV are subjected to a contact reaction, and the compound V is obtained after the solvent is evaporated; (3) in the presence of a fourth organic solvent and an acid binding agent, the compound V and acryloyl chloride are subjected to a contact reaction to obtain the cyanostilbene structural monomer; The second preparation method comprises the following steps: (1) in the presence of the fifth organic solvent and the third basic regulator, the compound VI and the compound VII are subjected to a contact reaction to obtain the compound VIII; (2) in the presence of the sixth organic solvent and the second catalyst, the compound VIII and DMF are subjected to a contact reaction to obtain compound IX; (3) in the presence of the seventh organic solvent, the compound X is contacted and reacted with NBS to obtain compound XI; (4) in the presence of the eighth organic solvent, the ninth organic solvent, the third catalyst and the Na ₂ CO ₃ aqueous solution, the compound XI and the compound XII are subjected to a contact reaction to obtain the compound XIII; (5) in the presence of the second organic solvent, the first basic regulator and the first catalyst, the compound XIII and the compound II are subjected to a contact reaction to obtain the compound XIV; (6) in the presence of the third organic solvent and the second basic regulator, the compound XIV and the compound IX are subjected to a contact reaction, and the compound XV is obtained after the solvent is evaporated; (7) In the presence of a fourth organic solvent and an acid binding agent, the compound XV and acryloyl chloride are subjected to a contact reaction to obtain the cyanostilbene structural monomer. Wherein, the structural formula of the compound I is:

The structural formula of the compound II is:

In the formula, n is an integer of 1-9, and X is selected from a bromine atom or an iodine atom; The structural formula of the compound III is

In the formula, n is an integer from 1 to 9; The structural formula of the compound IV is:

wherein, R is selected from the structural groups represented by the R ₁ , R ₂ , R ₃ or R ₄ , The structural formula of the compound V is:

In the formula, n is an integer from 1 to 9; The structural formula of the compound VI is:

The structural formula of the compound VII is:

The structural formula of the compound VIII is: The structural formula of the compound IX is: The structural formula of the compound X is:

The structural formula of the compound XI is:

The structural formula of the compound XII is:

The structural formula of the compound XIII is:

The structural formula of the compound XIV is:

In the formula, n is an integer from 1 to 9; The structural formula of the compound XV is:

In the formula, n is an integer of 1-9. 4. The reversible light-regulated fluorescent liquid crystal nanoparticle according to claim 3, wherein, The reaction conditions of each step in the first preparation method include the following: In step (1): the first alkaline regulator is anhydrous potassium carbonate, and the first catalyst is potassium iodide; the mol ratio of the compound I, compound II, anhydrous potassium carbonate and potassium iodide is 1:3- 10:3-10:0.1-1, the second organic solvent is a polar organic solvent, the temperature of the contact reaction is 30-80°C, and the time is 12-24h; In step (2): the second alkaline regulator is potassium tert-butoxide; the molar ratio of compound III, compound IV and potassium tert-butoxide is 2-3:1:0.1-0.5, and the contact reaction The temperature is 30-80℃, and the time is 2-8h; In step (3): the acid binding agent is triethylamine; the molar ratio of the compound V, acryloyl chloride and triethylamine is 1:3-4:3-5, and the temperature of the contact reaction is 0- 40℃, the time is 12-24h; The reaction conditions of each step in the second preparation method include the following: In step (1): the third alkaline regulator is NaH or NaOH; the molar ratio of the compound VI, the compound VII and the third alkaline regulator is 1:1-3:1-10, so the The temperature of the contact reaction is 0-40 ° C, and the time is 1-2 hours; In step (2): the molar ratio of the compound VIII, DMF and the second catalyst is 1:2-5:0.1-1, the first catalyst is POCl , the temperature of the contact reaction is 30-70 ° C, and the time for 12-24h; In step (3): the molar ratio of the compound X to NBS is 1:1-3, the temperature of the contact reaction is 0-40°C, and the time is 1-5h; In step (4): the molar ratio of the compound XI, the compound XII and the third catalyst is 1:1-3:0.1-1, and the mass fraction of the Na ₂ CO ₃ aqueous solution is 10-30%; Step (5) includes: the first alkaline regulator is anhydrous potassium carbonate, and the first catalyst is potassium iodide; the mol ratio of compound XIII, compound II, anhydrous potassium carbonate and potassium iodide is 1:3-10: 3-10: 0.1-1, the second organic solvent is a polar organic solvent, the temperature of the contact reaction is 30-80°C, and the time is 12-24h; Step (6) includes: the second alkaline regulator is potassium tert-butoxide; the molar ratio of compound XIV, compound IX and potassium tert-butoxide is 2-4:1:0.2-1, and the contact reaction is 2-4:1:0.2-1. The temperature is 30-80℃, and the time is 2-8 hours; Step (7) includes: the acid binding agent is triethylamine; the molar ratio of the compound XV, acryloyl chloride and triethylamine is 1:3-4:3-5, and the temperature of the contact reaction is 0- 40℃, the time is 12-24h. 5. The reversible light-adjustable fluorescent liquid crystal nanoparticle according to claim 1, wherein the diarylethene compound has a structure as shown in general formula IV; wherein, X ₁ and X ₂ are each independently selected from R ₅ , R ₆ , R ₇ , R ₈ , R ₉ or R ₁₀ represented by the structural group, X ₁ , X ₂ are the same or different;

6. The reversible light-adjustable fluorescent liquid crystal nanoparticle according to claim 1, wherein the diarylethene compound is selected from the group consisting of formulas b-1, b-2, b-3, b-4, b-5 One or more of the diarylethene compounds of the structure shown;

7 . The reversible light-adjustable fluorescent liquid crystal nanoparticles according to claim 1 , wherein the nematic liquid crystal monomer is at least one of C4M, C6M and C8M. 8 . 8. The reversible light-regulating fluorescent liquid crystal nanoparticle according to claim 1, wherein, In step (1): the mass ratio of the nematic liquid crystal monomer to the cyanostilbene structural monomer is 70-200:1; the mass ratio of the diarylene compound to the cyanostilbene structural monomer is 1-9 : 1; the first organic solvent is dichloromethane and/or chloroform, and the mass ratio of the first organic solvent to the nematic liquid crystal monomer is 2-10:1; In step (2): based on the total weight of the mixture of the cyanostilbene structural monomer and the nematic liquid crystal monomer, the content of the thermal initiator is 0.1-2 wt %, and the content of the stabilizer is 1-2 wt %. 10wt%, the added amount of the emulsifier is 10-20wt%; the volume ratio of water to the first organic solvent is 30-50:1, and the emulsifier is sodium lauryl sulfate or 11-(acryloyl oxy) sodium undecanoate, the thermal initiator is at least one of azobisisobutyronitrile, azobisisovaleronitrile and benzoyl peroxide, and the stabilizer is hexadecanol, normal At least one of hexadecane, stearyl methacrylate and stearyl acrylate, and the emulsification time is 1-6h; In step (3): the power of the ultrasonic homogenization is 120-450W, and the time is 5-30min; In step (4): the temperature of the heating polymerization is 60-80° C., and the time is 12-24 h. 9. A reversible light-regulated color fluorescent ink, characterized in that, in terms of the total weight of the reversible light-regulated color fluorescent ink, the reversible light-regulated color fluorescent ink comprises: 3-10wt% in claims 1-8 Any one of the reversible light-regulated fluorescent liquid crystal nanoparticles, 2-6wt% of a film-forming agent, 5-45wt% of a water-soluble organic solvent, 2-4wt% of an emulsifier, 0.1-2wt% of a pH adjuster and 0-70 wt% water, and the sum of the components is 100 wt%. 10. The reversible light-regulated color fluorescent ink according to claim 9, wherein the film-forming agent is at least one of polyvinyl alcohol, water-based polyurethane, polyethylene glycol, chitosan and gelatin; the water-soluble The organic solvent is at least one of ethylene glycol, glycerol, diethylene glycol monomethyl ether, propylene glycol methyl ether and dipropylene glycol dimethyl ether; the pH regulator is ammonia water, NaHCO , Na ₂ CO ₃ and At least one of triethanolamine; the emulsifier is at least one of sodium lauryl sulfate, 11-(acryloyloxy) sodium undecanoate and polyvinyl alcohol.

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