CN112625240B

CN112625240B - Fluorescent polymer, preparation and application

Info

Publication number: CN112625240B
Application number: CN202011492069.2A
Authority: CN
Inventors: 赵晓燕; 吴谦; 胡嘉慧; 王睿晨; 魏慧丹; 张光明; 汪称意
Original assignee: Changzhou University
Current assignee: Changzhou University
Priority date: 2020-12-16
Filing date: 2020-12-16
Publication date: 2022-09-23
Anticipated expiration: 2040-12-16
Also published as: CN112625240A

Abstract

The invention discloses a fluorescent polymer, preparation and application, wherein the fluorescent polymer has the following structure:

the polymer and the material thereof have simple synthesis process, excellent fluorescence characteristic and good application prospect in the fields of chemical sensing and anti-counterfeiting identification.

Description

Fluorescent polymer, preparation and application

Technical Field

The invention belongs to the field of optical imaging, and particularly relates to a fluorescent polymer, and preparation and application thereof.

Background

In recent years, fluorescent materials have been widely used in various fields such as optical imaging, chemical sensing, and anti-counterfeit identification. Therefore, it is important to select a material having high sensitivity and high fluorescence intensity when used. Fluorescent polymers stand out in a variety of fluorescent materials due to their excellent processability and dimensional stability. The fluorescent polymer can be used for preparing the flexible fluorescent sensor based on the two advantages, so that the use value and the use range of the fluorescent sensor are greatly improved.

However, the conventional fluorescent polymer also has a fatal defect that when the polymer is prepared into a solid material, groups in a molecular chain are highly aggregated, so that a fluorescence quenching phenomenon is generated, and the fluorescent polymer generates a phenomenon of non-luminescence or fluorescence intensity reduction, so that the use efficiency of the fluorescent polymer is influenced. Thereby limiting the application of the organic light-emitting polymer in the solid optical field. In addition, when applied to anti-counterfeiting identification, the fluorescent polymer material also has the defects of high fusion cost with the substrate material, high loss rate, poor fluorescent effect, inconvenient detection means and the like, and is not beneficial to the practical application and popularization of the fluorescent polymer.

Disclosure of Invention

Aiming at the problems, the invention provides a fluorescent polymer, and preparation and application thereof.

The technical purpose is achieved, the technical effect is achieved, and the invention is realized through the following technical scheme:

a fluorescent polymer having the formula:

as a further improvement of the invention, n is 50 to 100.

As a further improvement of the invention, the polymer is readily soluble in polar aprotic solvents or low boiling organic solvents, and the solubility of the polymer in the organic solvent is from 18 wt% t to 30 wt%.

The invention also provides a method for preparing the fluorescent polymer, which comprises the following steps:

the method comprises the following steps: preparation of monomer A

The preparation steps of the monomer A are as follows:

1.1) mixing 1-pyrene formaldehyde and 2, 6-dimethyl aniline according to a molar ratio of 1: 2-1:5, adding catalyst concentrated hydrochloric acid, heating to 120-170 ℃ in the nitrogen atmosphere, reacting for 4-8h, and finishing the reaction;

1.2) adding ethanol into a reaction system, adjusting the pH value to be more than or equal to 7 by using a sodium hydroxide solution, carrying out layered filtration, then drying, and recrystallizing the dried powder by using toluene again to obtain a monomer A;

step two: preparation of fluorescent polymers

2.1) mixing the monomer A and the ether anhydride into m-cresol according to a ratio, adding a catalyst isoquinoline, and heating to 170-190 ℃ under the atmosphere of nitrogen to perform polycondensation reaction for 4-8 h;

2.2) after the reaction is finished, the reactant is poured into ethanol for sedimentation, and the mixture is sequentially filtered and washed, and finally the temperature is 120 DEG C

And drying for 6 hours in vacuum to obtain a white polymer and obtain the target fluorescent polymer.

As a further improvement of the invention, in the first step, the 1-pyrene formaldehyde is mixed according to the mass ratio of 1: 1-1: 3 and toluene, wherein the addition amount of the concentrated hydrochloric acid is 0.1-0.3 time of the mass of the 2, 6-dimethylaniline.

As a further improvement of the present invention, in the second step, the molar ratio of the monomer a to the ether anhydride is 1:1, the using amount of the m-cresol is 7-14 times of the total mass of the monomer A and the ether anhydride; the dosage of the catalyst is 1-4% of the mass of the m-cresol.

The invention also provides a method for applying the fluorescent polymer, which comprises the following steps:

dissolving a fluorescent polymer in an organic solvent C to prepare an electrostatic spinning solution, wherein the concentration of the electrostatic spinning solution is 3-8 wt%;

and spraying the electrostatic spinning solution on a substrate material by adopting an electrostatic spinning process.

As a further improvement of the invention, the electrostatic spinning process comprises the steps of spinning solution advancing speed of 2.5mL/h, spinning voltage of 12kV, nozzle aperture of 0.5mm, receiving distance of 15cm and air relative humidity of 35%.

As a further improvement of the invention, the thickness of the sprayed fluorescent polymer film is 20-30 μm.

The invention has the beneficial effects that:

1. the fluorescence property is good, and particularly under the condition of aggregation state, the phenomenon of fluorescence quenching is not easy to occur. (ii) a

2. The solubility is good, the processability of the polyimide material is promoted, and the morphology of the material is easier to control by combining an electrostatic spinning process, so that the polyimide material has wide application and can be used for anti-counterfeiting identification and chemical sensor manufacturing in multiple aspects.

Drawings

FIG. 1 is a nuclear magnetic hydrogen spectrum of a diamine monomer;

FIG. 2 is an infrared spectrum of diamine monomers;

FIG. 3 is a nuclear magnetic hydrogen spectrum of a polymer;

FIG. 4 is an infrared spectrum of a polymer;

FIG. 5 is a flow chart of the preparation of the electrostatic spraying anti-counterfeiting marker;

FIG. 6 is an SEM image of an electrostatic spray of a polymer;

FIG. 7 is a fluorescence emission spectrum of a polymer film made with a thickness of 20um under UV excitation;

FIG. 8 is a fluorescent image of the anti-counterfeiting marker under the irradiation of an ultraviolet lamp.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.

The following detailed description of the principles of the invention is provided in connection with the accompanying drawings.

The structural formula of the fluorescent polymer used by the fluorescent material prepared in the invention is as follows:

wherein n is 50-100, and the molecular weight of the polymer is controlled to be 50,000-90,000 (Mn).

Secondly, the method for preparing the fluorescent polymer comprises the following steps:

the method comprises the following steps: preparation of monomer A

The synthetic route is as follows:

the specific synthetic route is as follows: adding 1-pyrene formaldehyde, 2, 6-dimethylaniline, a solvent and a catalyst into a three-neck flask, heating to 120-170 ℃ in a nitrogen atmosphere, and reacting for 4-8h to finish the reaction.

Wherein the mol ratio of the 1-pyrene formaldehyde to the 2, 6-dimethylaniline is 1: 2-1: 5; the solvent is toluene, and the dosage of the solvent is 1-3 times of the mass of 1-pyrene formaldehyde; the catalyst is concentrated hydrochloric acid (the concentration is 37.5 percent), and the dosage is 0.1 to 0.3 time of the mass of the 2, 6-dimethylaniline.

After the reaction is finished, pouring the product into ethanol, adding a sodium hydroxide solution to adjust the pH value to be more than or equal to 7, and standing for layering. The system was filtered to give a yellow powder, which was dried in an oven at 100 ℃ for 2 h. And adding the yellow powder into toluene for thermal dissolution, standing, filtering, recrystallizing and purifying to obtain light white crystal powder, and further performing vacuum drying at 120 ℃ for 6 hours to obtain the simple substance A.

Step two: preparation of fluorescent polymers

Synthesizing the ether anhydride polyimide, wherein the structural formula is as follows:

the synthetic route is as follows:

in a three-neck flask, adding a mixture of 1:1, heating the simple substance A, the ether anhydride, the solvent and the catalyst to 170-190 ℃ in the nitrogen atmosphere, reacting for 4-8h, finishing the reaction, pouring the reactant into ethanol for settling, further filtering and washing. After drying at 120 ℃ for 6h in vacuo, a white polymer was obtained.

Wherein the solvent is m-cresol, and the using amount of the solvent is 7-14 times of the mass of the diamine and dianhydride monomers; the catalyst is isoquinoline, and the dosage of the catalyst is 1 to 4 percent of the mass of the m-cresol.

A. Polymer preparation examples:

the first embodiment is as follows:

(1) synthesis of monomer a:

7g of 1-pyrene formaldehyde and 18.419g of 2, 6-dimethylaniline (molar ratio 1:5) were added to a three-necked flask, 18g of toluene was added as a solvent, 2g of concentrated hydrochloric acid was added as a catalyst, and the mixture was heated to 165 ℃ under a nitrogen atmosphere. The reaction was terminated after 8 h. Adding ethanol into the obtained product, adjusting pH to be more than or equal to 7 with sodium hydroxide solution, standing for layering, filtering the system to obtain yellow powder, and drying in an oven at 100 ℃ for 2 h. And adding the yellow powder into toluene for thermal dissolution, standing for 6 hours, filtering to obtain light white crystal powder, and performing vacuum drying at 120 ℃ for 6 hours to obtain a yellow diamine monomer. The mass of the obtained diamine monomer was 11.886g, and the yield was 87.76%.

(2) Synthesis of Polymer:

adding 6mmol of simple substance A and 6mmol of ether anhydride into a three-neck flask, adding 50mL of m-cresol as a solvent, adding 8mL of isoquinoline as a catalyst, heating to 190 ℃ in nitrogen atmosphere, reacting for 8h, finishing the reaction, pouring the reactant into ethanol for settling, further filtering and washing. After drying at 120 ℃ for 6h in vacuo, a white polymer was obtained.

Example two:

(1) synthesis of monomer a:

7g of 1-pyrene formaldehyde and 7.368g of 2, 6-dimethylaniline (molar ratio 1:2) were added to a three-necked flask, 18g of toluene was added as a solvent, 2g of concentrated hydrochloric acid was added as a catalyst, and the mixture was heated to 150 ℃ under a nitrogen atmosphere. The reaction was terminated after 6 h. Adding ethanol into the obtained product, adjusting pH to be more than or equal to 7 with sodium hydroxide solution, standing for layering, filtering the system to obtain yellow powder, and drying in an oven at 100 ℃ for 2 h. Adding the yellow powder into toluene for thermal dissolution, standing for 6h, filtering to obtain light white crystal powder, and vacuum drying at 120 ℃ for 6h to obtain the yellow diamine monomer. The mass of the obtained diamine monomer was 11.748g, and the yield was 86.74%.

(2) Synthesis of the Polymer:

adding 5mmol of simple substance A and 5mmol of compound 5 into a three-neck flask, adding 40mL of m-cresol as a solvent, adding 5mL of isoquinoline as a catalyst, heating to 180 ℃, reacting for 6h, finishing the reaction, pouring the reactant into ethanol for settling, further filtering and washing. After drying for 6h under vacuum at 120 ℃ a white polymer was obtained.

B. Characterization of Properties

1.1) the yield calculation shows that the obtained monomer A has less by-products and the yield can reach 86 percent.

1.2) structural characterization of the prepared monomer A is shown in FIGS. 1 and 2: as can be seen from FIG. 1, the integral value of each absorption peak of the synthesized product is completely consistent with the number of protons in the designed structural formula, the proton on the amino group appears at 4.7, and the aldehyde group proton peak does not appear. FIG. 2 at 3356cm ^-1 And 3440cm ^-1 Symmetric and asymmetric characteristic peaks of primary amine appear on the left and the right respectively, and the bending vibration of N-H is overlapped with the vibration of a benzene ring framework at 1616cm ^-1 And 1504cm ^-1 Two absorption peaks appear; and at 1690cm ^-1 ～1715cm ^-1 No aromatic aldehyde group characteristic peak appears in between. Infrared and nuclear magnetic analysis results confirmed that the diamine monomer was successfully synthesized.

And the monomer can be seen from the nuclear magnetic spectrum of the monomer without a hetero peak, the obtained diamine monomer is seen to have high purity, and the impurity content is little, so that the method can be seen.

2.1) As can be seen from FIG. 3, the integral value of each absorption peak of the synthesized product completely agrees with the number of protons in the designed structural formula, and FIG. 4 shows that 1783cm ^-1 ，1718cm ^-1 ，1363cm ^-1 A stretching vibration peak and a carbon-nitrogen bond characteristic peak of the polyimide carbonyl appear at 1225cm ^-1 The characteristic peak of ether bond appears. 3300-3500 cm ^-1 The amino peak in between disappeared, indicating that the desired polymer was synthesized from the diamine monomer.

2.2) the molecular weight of the polymer was measured by GPC (Mn 50,000-90,000) to further demonstrate that the purity of the monomer was high and that the polycondensation reaction proceeded equimolar only with the high purity monomer to give a high molecular weight polymer.

2.3) dissolving the obtained target fluorescent polymer in different organic solvents, wherein the organic solvent is selected from polar aprotic solvents such as N-methylpyrrolidone (NMP), N-dimethylacetamide (DMAc), N-Dimethylformamide (DMF), or low boiling organic solvents such as CHCl ₃ ,、CH ₂ Cl ₂ And the properties of the solutions were tested as a function of the amount of solution, as detailed in the following table:

table 1: solubility of fluorescent Polymer

Solvent(s)	NMP	DMAc	DMF	CHCl ₃	CH ₂ Cl ₂
						Maximum amount of dissolution (wt%)	26	30	30	22	18

The physical properties of the polymer from the above table show that the polymer has good solubility properties.

Application of fluorescent polymer

The method comprises the following basic steps:

(1) dissolving a fluorescent polymer in an organic solvent C to prepare an electrostatic spinning solution, wherein the concentration of the electrostatic spinning solution is 3-8 wt%, and the solvent for preparing the polymer solution is one or more of glacial acetic acid, N, N-dimethylformamide, N, N-dimethylacetamide, ethanol, formic acid, trichloromethane, tetrahydrofuran or N-methylpyrrolidone;

(2) and spraying the electrostatic spinning solution on a substrate material by adopting an electrostatic spinning process.

The substrate material can be selected from various materials, such as paper, non-woven fabric, plastic plate, glass plate, fiber membrane, etc.

The adopted electrostatic spinning process comprises the following steps: the spinning solution is propelled at a speed of 2-4.5mL/h, the spinning voltage is 12-24kV, the orifice aperture is 0.5-1mm, the receiving distance is 15-25cm, and the spinning solution is dried for 15-30min at 40-60 ℃ after spraying.

For specific applications see the examples below.

Anti-fake mark making process

As shown in FIG. 5, a template printed with a typeface pattern, such as a template containing a Chinese character, is covered on a base material, and then 8 wt% of a polyvinyl alcohol water-soluble adhesive is uniformly coated on the template and left to stand for 15 min. Dissolving a polymer in DMAc, heating at 60 ℃, magnetically stirring for dissolving for 2h to prepare a polymer solution with the concentration of 7 wt%, and standing and cooling for 2h after the polymer is fully dissolved to obtain electrostatic spraying liquid. The polymer solution was then introduced into a syringe at a forwarding speed of 1.5mL/h, a spinning voltage of 15kV, an orifice diameter of 0.7mm and a receiving distance of 12 cm. And after the spraying is finished, drying for 20min at 50 ℃, and removing the template to obtain the ether anhydride polyimide coating substrate material with Chinese-character patterns.

As can be seen from FIG. 6, the polymer spray was granular and had a dense structure, no significant gaps between the granules, uniform size, and an average particle size of 10 μm.

As can be seen from FIG. 7, the fluorescence emission spectrum of the sprayed film (film thickness 20 μm) from which it can be seen that the fluorescent polymer of the present invention still has a high fluorescence intensity in the state of aggregation.

As can be seen from FIG. 8, the anti-counterfeit marker generates obvious green fluorescence under the irradiation of the ultraviolet lamp, and has obvious fluorescence imaging effect.

In conclusion, the material obtained by the method has good fluorescent effect.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A fluorescent polymer characterized by: the structural formula of the fluorescent polymer is as follows:

and n is 50-100.

2. The fluorescent polymer of claim 1, wherein: the polymer is easily soluble in polar aprotic solvents or low-boiling organic solvents, and the solubility of the polymer in the organic solvents is 18-30 wt%.

3. A method for preparing a fluorescent polymer according to any of claims 1-2, comprising the steps of:

the method comprises the following steps: preparation of monomer A

The preparation steps of the monomer A are as follows:

1.1) mixing 1-pyrene formaldehyde and 2, 6-dimethylaniline according to the molar ratio of 1: 2-1:5, adding catalyst concentrated hydrochloric acid, heating to 120-170 ℃ in the nitrogen atmosphere, reacting for 4-8h, and finishing the reaction;

1.2) adding ethanol into the reaction system, adjusting the pH value to be more than or equal to 7 by using a sodium hydroxide solution, carrying out layered filtration, then drying, and recrystallizing the dried powder by using toluene again to obtain a monomer A;

step two: preparation of fluorescent polymers

2.2) after the reaction is finished, pouring the reactant into ethanol for sedimentation, sequentially filtering and washing, and finally drying in vacuum at 120 ℃ for 6h to obtain a white polymer and obtain the target fluorescent polymer.

4. The production method according to claim 3, characterized in that: in the first step, the mass ratio of the 1-pyrene formaldehyde to the water is 1: 1-1: 3 and toluene, wherein the addition amount of the concentrated hydrochloric acid is 0.1-0.3 time of the mass of the 2, 6-dimethylaniline.

5. The production method according to claim 3, characterized in that: in the second step, the molar ratio of the monomer A to the ether anhydride is 1:1, the using amount of the m-cresol is 7-14 times of the total mass of the monomer A and the ether anhydride; the dosage of the catalyst is 1-4% of the mass of the m-cresol.

6. Method of use of a fluorescent polymer according to any of claims 1-2, characterized in that:

7. The method of application according to claim 6, characterized in that: the electrostatic spinning process comprises the steps of spinning solution advancing speed of 2.5mL/h, spinning voltage of 12kV, nozzle aperture of 0.5mm, receiving distance of 15cm and air relative humidity of 35%.

8. The method of application according to claim 6, characterized in that: the thickness of the sprayed fluorescent polymer film is 20-30 μm.