CN114605960B - Reversible photothermal response adhesive, preparation method and application thereof - Google Patents

Abstract

The invention discloses a reversible photothermal response adhesive, a preparation method and application thereof. The adhesive is prepared by taking a monomer and a crosslinking agent as reactants, taking 1,5, 7-triad bicyclo (4.4.0) dec-5-ene-TBD-as an alkaline catalyst, taking 1, 6-hexanedithiol as an initiator, dissolving in an organic solution, and carrying out ring opening polymerization reaction on disulfide five-membered rings under heating conditions. The product has the excellent performances of photo-thermal control reversible adhesion, self-repairing and recycling, and has higher thermal stability, lower solid-liquid phase transition temperature and high adhesive strength.

Description

Reversible photothermal response adhesive, preparation method and application thereof

Technical Field

The invention relates to a new material and a preparation method thereof, in particular to a reversible photothermal response adhesive, and a preparation method and application thereof.

Background

The development of the adhesive greatly promotes the development of society, but the traditional adhesive has the problems of difficult cleaning and unrepeatable use, and hardly meets the requirement of temporary positioning or error positioning permission in the use process of the adhesive, and brings great challenges to the environment and resources. Therefore, the development of the environment-friendly and recyclable adhesive has positive effects on the aspects of environmental protection, resource conservation, new material development and the like. At present, the reversible adhesive has been widely applied to the fields of optics, electronics, medical treatment, automobiles, precision instruments and the like.

The bonding mechanism of the adhesive with different molecular structures is also different when the adhesive bonds different substances, so that different driving modes exist in reversible bonding. However, the difference between the reversible linkage system is mainly summarized into two main types, namely, non-covalent linkage and covalent linkage, and the covalent linkage system represented by disulfide bonds is currently one of the popular research in recent years. Because of the self-repairing adhesive with dynamic covalent bonds, the adhesive has higher cohesive strength, adhesive property and self-repairing property. Meanwhile, the light is used as a clean energy source, and has the characteristics of non-contact, remote in-situ and regional accurate control. Azobenzene is taken as a photochromic molecule, and the molecule can generate trans-cis isomerization reaction under the action of ultraviolet light and has certain photo-thermal response. After the polymer containing azobenzene molecules forms a network structure, the cis-trans isomerism of the polymer is inhibited due to a certain network limiting effect, and the light energy absorbed by the azobenzene group can be converted into a certain heat energy under the irradiation of ultraviolet light. Therefore, the azobenzene element is introduced into the disulfide dynamic covalent bond linking adhesive, and the preparation of the photo-thermal response reversible adhesive has good research prospect.

Disclosure of Invention

The invention aims to: the invention aims to provide a reversible photothermal response adhesive and a preparation method thereof.

The technical scheme is as follows: the adhesive with reversible photothermal response comprises the following steps:

(1) Under ice bath condition, aniline compound with substituent group at para position is dissolved in hydrochloric acid water solution with certain concentration, and sodium nitrite solution with certain concentration is added into the solution; dissolving phenol, sodium hydroxide and sodium bicarbonate with certain mass in water, dripping the solution of the phenol, the sodium hydroxide and the sodium bicarbonate into the solution of the sodium bicarbonate, stirring for reaction, and purifying for a certain time to obtain a monomer precursor;

(2) Dissolving the monomer precursor in the step (1), bromohydrin and anhydrous potassium carbonate in acetone according to a certain proportion, adding trace potassium iodide, carrying out reflux reaction for a certain time under the protection of nitrogen, and purifying the obtained crude product by column chromatography to obtain a monomer intermediate;

(3) Dissolving the monomer intermediate in the step (2) and EDC and DMAP in methylene dichloride according to a certain proportion, and magnetically stirring and dissolving under the protection of nitrogen; then adding triethylamine and lipoic acid in a certain proportion in turn, reacting for a certain time at normal temperature, purifying the obtained crude product by column chromatography to obtain a monomer, wherein the structural formula is shown as follows:

(4) Uniformly mixing hydroquinone and p-hydroxybenzoic acid in a certain proportion, heating and stirring for a certain time under the protection of nitrogen, pouring the obtained product into cold water while the product is hot, and carrying out suction filtration; dissolving the crude product in a mixed solution of ethanol and water, and recrystallizing to obtain a cross-linking agent precursor;

(5) Dissolving the cross-linking agent precursor in the step (4), bromohydrin, anhydrous potassium carbonate and tetrabutylammonium bromide in a certain proportion in acetone, carrying out reflux reaction for a certain time under the protection of nitrogen, and purifying the obtained crude product by column chromatography to obtain a cross-linking agent intermediate;

(6) Dissolving the cross-linking agent intermediate in the step (5) and EDC and DMAP in methylene dichloride according to a certain proportion, and magnetically stirring and dissolving under the protection of nitrogen; then adding triethylamine and lipoic acid in a certain proportion in turn, reacting for a certain time at normal temperature, purifying the obtained crude product by column chromatography to obtain the cross-linking agent, wherein the structural formula is shown as follows:

(7) Taking the monomer in the step (3) and the crosslinking agent in the step (6) as main reactants, taking TBD as an alkaline catalyst and 1, 6-hexanedithiol as an initiator, dissolving the monomers in a proper amount of toluene solution according to a certain proportion, and carrying out ring-opening polymerization on disulfide five-membered rings under the heating condition to obtain a polymer adhesive;

(8) And (3) selecting a glass plate as a matrix, and adhering the polymer adhesive prepared in the step (7) to the glass plate by a heating and ultraviolet irradiation mode to test and verify the excellent reversible performance of the adhesive.

The adhesive with reversible photothermal response is prepared by the method.

The application of the reversible photothermal response adhesive in preparing the reversible photosensitive adhesive.

Preferably, the molar ratio of the aniline compound with substituent groups at the para position in the step (1), sodium nitrite, phenol, sodium hydroxide and sodium bicarbonate is 1:1:1:1.5;

preferably, in the step (2), the molar ratio of the monomer precursor, bromohydrin and anhydrous potassium carbonate is 1:1.5:1.5;

preferably, the molar ratio of monomer intermediate, EDC, DMAP, triethylamine, lipoic acid in step (3) is 1:1.2:0.2:1.5:1.5;

preferably, the molar ratio of hydroquinone to p-hydroxybenzoic acid in step (4) is 10:1;

preferably, the molar ratio of the cross-linking agent precursor, bromoalcohol, anhydrous potassium carbonate and tetrabutylammonium bromide in the step (5) is 1:3:3:0.5;

preferably, the molar ratio of the adhesive intermediate, EDC, DMAP, triethylamine and lipoic acid in the step (6) is 1:2.4:0.4:3:3;

preferably, the molar ratio of monomer, adhesive, TBD, 1, 6-hexanedithiol in step (7) is 1:0.2:0.5:0.5.

The reversible photothermal response adhesive takes the monomer prepared by synthesis and the cross-linking agent as main raw materials, and the basic catalyst TBD is added to open the disulfide five-membered ring, and the polymerization reaction is carried out under the action of the initiator 1, 6-hexanedithiol to prepare the reticular polymer adhesive. Under the irradiation of ultraviolet light, azobenzene molecules are limited in cis-trans isomerism in a polymer network system, so that light energy can be converted into heat energy. Under the irradiation of ultraviolet light with proper optical function density, the azobenzene molecule can raise the temperature of the polymer system to the phase transition temperature, so that the adhesive is subjected to solid-liquid transition, and the reversible bonding performance of the adhesive is provided. In order to be more suitable for the application of the adhesive, the mixed solution in the step (7) is poured into a polytetrafluoroethylene groove template to prepare the polymer film, and the application scene of the adhesive can be adapted by cutting. The glass surface has more silicon hydroxyl groups, is easy to adhere and has better ultraviolet light transmittance, so the invention adopts the glass as an experimental base material to explore and display the performance of the reversible photo-thermal response adhesive.

The beneficial effects are that: compared with the prior art, the invention has the following advantages:

1. the self-repairing and recycling performance is achieved. By introducing azobenzene units and disulfide five-membered ring units, the polymer adhesive is endowed with the performances of reversible adhesion and degumming under photo-thermal regulation, and meanwhile, the polymer adhesive has the performances of self-repairing and recycling.

2. The preparation process flow is simple. The glue can be formed without other additives. The prepared polymer adhesive has the advantages of higher thermal stability, lower solid-liquid phase transition temperature, simple and convenient adhesion mode, high adhesion strength and the like.

3. The cleaning is simple and convenient, and the cleaning can be repeatedly used. The adhesive well solves the problems of difficult cleaning and unrepeatable use of the traditional adhesive. The adhesive contains azobenzene elements, can convert light energy into heat energy, and simultaneously disulfide bonds are used as dynamic covalent bonds, so that the adhesive has higher cohesive strength, adhesive property and self-repairing property.

Drawings

FIG. 1 is an ultraviolet absorption spectrum of a monomer M1 prepared in example I in toluene solution;

FIG. 2 is an ultraviolet absorption spectrum of a polymer adhesive film prepared in example III;

FIG. 3 is a thermogravimetric analysis (TG) plot of a film of polymer adhesive in example three;

FIG. 4 is a Differential Scanning Calorimeter (DSC) plot of a polymer adhesive film of example three;

FIG. 5 is a stress-strain diagram of a polymer adhesive film at room temperature in example three;

FIG. 6 is a graph of storage modulus (G ') and loss modulus (G') of a polymer adhesive film of example III as a function of temperature at a constant shear strain;

FIG. 7 is a graph showing the comparison of the adhesive strength of a polymer adhesive on a glass substrate in three different adhesive modes of initial heat curing, ultraviolet irradiation secondary curing after debonding, and heating self-repairing curing after scraping.

Detailed Description

Example 1

The synthesis and preparation process of the monomer M1 used for the reversible adhesive with the photo-thermal response comprises the following specific steps:

(1) 4-aminobenzonitrile (11.8 g,0.1 mol) was dissolved in aqueous hydrochloric acid (0.4% by volume of concentrated HCl to deionized water) to form solution 1; sodium nitrite (6.9 g,0.1 mol) was dissolved in deionized water to form solution 2; dropwise adding the solution 2 into the solution 1 to form a solution 3; phenol (9.4 g,0.1 mol), sodium hydroxide (4.0 g,0.1 mol), sodium bicarbonate (12.6 g,0.15 mol) were dissolved in deionized water to prepare a solution 4; dropwise adding the solution 3 into the solution 4, wherein the above operations are carried out under an ice bath; after 2h of reaction, carrying out suction filtration, water washing and drying to obtain orange-red solid, namely monomer precursor (16.6 g, 74.4%);

(2) The monomer precursor (2.23 g,10 mmol), 6-bromo-n-hexanol (2.72 g,15 mmol) and anhydrous potassium carbonate (2.07 g,15 mmol) in step (1) were dissolved in acetone, and a trace amount of potassium iodide was added thereto, and the mixture was refluxed at 60℃for 24 to 48 hours under nitrogen protection. Then cooled to room temperature and filtered, and the solvent was removed under reduced pressure to give a crude product. Purifying the obtained crude product by silica gel column chromatography, wherein the eluent ratio is Petroleum Ether (PE): ethyl Acetate (EA) =10:1, affording an orange solid, the monomer intermediate (1.86 g, 57.6%);

(3) The monomer intermediate (1.62 g,5 mmol), EDC (1.15 g,6 mmol) and DMAP (0.12 g,1 mmol) in step (2) were dissolved in dichloromethane and magnetically stirred under nitrogen; triethylamine (1.26 g,7.5 mmol) and lipoic acid (1.55 g,7.5 mmol) were added dropwise to the reaction system in this order, and the mixture was reacted at room temperature for 24 hours to 48 hours. Purifying the obtained crude product by column chromatography, wherein the eluent ratio is PE: ea=30:1, giving monomer M1 (1.52 g, 59.8%) as an orange-yellow powder. The nuclear magnetic hydrogen spectrum data are ¹ H NMR(600MHz，CDCl ₃ )δ7.94(dd，J＝8.9，2.3Hz，4H)，7.79(d，J＝8.6Hz，2H)，7.01(d，J＝9.0Hz，2H)，4.08(dt，J＝18.1，6.6Hz，4H)，3.59-3.54(m，1H)，3.20-3.15(m，1H)，3.11(t，J＝12.4Hz，1H)，2.46(ddd，J＝19.2，6.6，5.5Hz，1H)，2.32(t，J＝7.4Hz，2H)，1.90(d，J＝19.6Hz，1H)，1.85(d，J＝15.1Hz，2H)，1.72-1.64(m，6H)，1.55(s，2H)，1.45(t，J＝18.1Hz，4H)。

Weighing a proper amount of monomer M1, dissolving in toluene, and preparing into a solution with a concentration of 5X10 ^-5 mol/L solution. Under the excitation of 365nm ultraviolet light, the azobenzene unit in the monomer generates cis-trans isomerism, and the characteristic absorption peak of the trans isomer at 365nm is reduced. The change in ultraviolet absorbance of the monomer solution at different irradiation times was recorded and the results are shown in fig. 1.

Example two

The synthesis and preparation process of the cross-linking agent C1 used for the reversible adhesive with the photo-thermal response comprises the following specific steps:

(1) Hydroquinone (110.11 g,1.0 mol) and p-hydroxybenzoic acid (13.81 g,0.1 mol) are put into a three-neck flask, and reacted for 6 hours at 260 ℃ under the protection of nitrogen, and the obtained product is poured into cold water while being hot, and filtered by suction; the crude product was dissolved in ethanol in the ratio: recrystallisation from a water=1:1 (volume ratio) solution gives a white solid, the crosslinker precursor (11.62 g, 50.5%);

(2) The crosslinker precursor (3.0 g,13 mmol) in (1), 6-bromo-n-hexanol (7.1 g,39 mmol), anhydrous potassium carbonate (5.4 g,39 mmol) and tetrabutylammonium bromide (2.1 g,6.5 mmol) were dissolved in acetone and reacted under reflux at 60℃for 24h-48h under nitrogen protection. Then cooled to room temperature and filtered, and the solvent was removed under reduced pressure to give a crude product. Purifying the obtained crude product by silica gel column chromatography, wherein the eluent ratio is PE: ea=5:1, yielding a white solid, the crosslinker intermediate (3.15 g, 56.2%);

(3) The monomer intermediate (2.15 g,5 mmol), EDC (2.3 g,12 mmol) and DMAP (0.25 g,2 mmol) in (2) were dissolved in anhydrous dichloromethane and magnetically stirred under nitrogen; triethylamine (1.52 g,15 mmol) and lipoic acid (3.10 g,15 mmol) were added dropwise to the reaction system and dissolved in 15ml of dichloromethane, and reacted at room temperature for 24-48 h. After completion of the reaction, the mixture was extracted three times with saturated brine, and the organic phase was separated and dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure to give a crude product. The crude product obtained is obtained by passing through siliconPurifying by gel column chromatography, wherein the eluent ratio is PE: ea=10:1, yielding crosslinker C1 (1.86 g, 46.2%) as a white powder. The nuclear magnetic hydrogen spectrum data are ¹ H NMR(600MHz，CDCl ₃ )δ8.13(d，J＝8.8Hz，2H)，7.10(d，J＝9.0Hz，2H)，6.96(d，J＝8.9Hz，2H)，6.91(d，J＝9.0Hz，2H)，4.09(t，J＝8.1Hz，4H)，4.04(t，J＝6.4Hz，2H)，3.96(t，J＝6.4Hz，2H)，3.57(d，J＝14.4Hz，2H)，3.20-3.16(m，2H)，3.11(t，J＝12.4Hz，2H)，2.46(d，J＝18.3Hz，2H)，2.32(t，J＝7.5Hz，4H)，1.91(d，J＝19.6Hz，2H)，1.85-1.78(m，4H)，1.72-1.63(m，12H)，1.54-1.43(m，16H)。

Example III

The preparation and performance verification of the reversible adhesive with photo-thermal response of the invention are as follows:

monomer M1 (51.1 mg,0.1 mmol), cross-linking agent C1 (16.2 mg,0.02 mmol) and TBD (7.0 mg,0.05 mmol) were weighed by an electronic balance, placed in a 5ml strain bottle, 1ml toluene solution was added, ultrasonic dissolution was performed at room temperature for 2min, 1, 6-hexanedithiol (7.5 mg,0.05 mmol) was added to the system after removal, and ultrasonic dissolution and dispersion were continued for 2min. The mixed solution was poured into a 2cm x 2cm polytetrafluoroethylene fluted template and placed in a 50 ℃ oven for 2h of reaction. Taking out the groove, scraping the film from the groove, airing for a period of time (about 12 h) and dispersing the residual solvent.

Ultraviolet absorption test of polymer adhesive film:

the polymer solution prepared in the above operation was spin-coated on a glass sheet (2.5 cm. Times.2.0 cm) at a rate of 300rad/s (10 s) +3000rad/s (30 s) by a spin coater, and then placed in an oven at 50℃for reaction to form a film for 2 hours. And cooling to room temperature, and testing the ultraviolet absorption change of the spin-coated film. Under the excitation of 365nm ultraviolet light, the azobenzene element in the polymer adhesive film is cis-trans-isomerised, and the characteristic absorption peak of the trans-isomer at 365nm is reduced. The change in ultraviolet absorption of the polymer adhesive film at various irradiation times was recorded and the results are shown in fig. 2.

Thermogravimetric analysis (Tg), differential Scanning Calorimeter (DSC) test of polymeric adhesive films:

the polymer adhesive film (8.0 mg) prepared by the method is weighed and subjected to thermogravimetric analysis and differential scanning calorimetric analysis at heating rates of 10 ℃/min and 5 ℃/min respectively, and the results are shown in fig. 3 and 4, so that the polymer adhesive film has good thermal stability and solid-liquid phase transition near 61 ℃.

Mechanical property test of polymer adhesive film:

the polymer adhesive film (7mm X2mm X0.1mm) prepared by the method was cut to a suitable size and tested for stress-strain properties at room temperature at a stretching rate of 2mm/min, and the results are shown in FIG. 5, which demonstrate that the polymer adhesive film has good ductility. The rheological behaviour of the polymer adhesive film (diameter: 8.0mm, height: 0.6mm sample) with increasing temperature (2 ℃/min) was then analyzed using the relevant instrument. The storage modulus (G ') and loss modulus (G') of the samples were measured at a frequency sweep of 10rad/s at a constant strain of 1%, and as shown in FIG. 6, G 'after more than 50 degrees will be greater than G', demonstrating the solid-liquid transition of the polymer adhesive film over this temperature range.

Adhesion strength and reversible performance test of polymer adhesive film:

(1) Two clean glass plates (2.5 cm X1.5 cm) with the same size are cut, a polymer adhesive film (1.5 cm X1.0 cm) with the proper size is cut and clamped between the glass plates, and the glass plates are placed on a hot table and are pressed by a weight of 250 g. Adjusting a heat table to raise the temperature to 80 ℃, preserving heat and hot pressing for 3min, cooling to room temperature, and adhering and fastening two glass plates by a polymer adhesive;

(2) At an optical functional density of 475mW/cm ² After 5min of irradiation with 365nm ultraviolet light, the two glass plates adhesively fastened by the polymer adhesive in (1) are degummed and separated. And then the positions of the two glass plates, to which the polymer adhesive is adhered, are adhered together, and then the two glass plates are simultaneously subjected to certain pressure by tweezers under the irradiation of 365nm ultraviolet light with the same optical function density. After 5min, removing ultraviolet light, and adhering and fastening the two glass plates again to finish the reversible process of ultraviolet debonding and secondary adhesion;

(3) In parallel experiments, the polymer adhesive is scraped from the glass plate after the debonding in the step (2), is placed between two new pieces of glass again, is heated and remolded on a hot table, and all parameters in the process are kept consistent, so that an adhesion sample after the self-repairing of the polymer adhesive is obtained. The adhesive strength test was carried out on the adhesive samples in (1) and (2), and the results are shown in FIG. 7, which shows that the polymer adhesive has good adhesive strength in all three states.

Claims (6)

1. A preparation method of a reversible photothermal response adhesive is characterized by comprising the following steps: taking a monomer and a crosslinking agent as reactants, adopting TBD as an alkaline catalyst and 1, 6-hexanedithiol as an initiator, dissolving in an organic solution, and carrying out ring-opening polymerization on disulfide five-membered rings under heating conditions to prepare the adhesive with reversible photothermal response;

the structural formula of the monomer is as follows:

monomer (C):

the structural formula of the cross-linking agent is as follows:

crosslinking agent:

2. the method for preparing the adhesive with reversible photothermal response according to claim 1, wherein the method comprises the following steps:

the preparation method of the monomer comprises the following steps:

(1) Dissolving aniline compounds with substituent groups at para positions and sodium nitrite in hydrochloric acid aqueous solution with a certain concentration to carry out diazotization reaction; dissolving phenol, sodium hydroxide and sodium bicarbonate in water, then dripping the former solution into the latter solution, stirring for coupling reaction, and performing suction filtration and purification to obtain a monomer precursor;

(2) Dissolving the monomer precursor in the step (1), bromohydrin, anhydrous potassium carbonate and potassium iodide in a solvent, carrying out reflux reaction under the protection of nitrogen, and purifying the obtained crude product by column chromatography to obtain a monomer intermediate;

(3) The monomer intermediate in the step (2) is stirred with EDC, DMAP, triethylamine and sulfur Xin Suanrong in a solvent at room temperature under the protection of nitrogen, and the obtained crude product is purified by column chromatography to obtain the monomer.

3. The method for preparing the adhesive with reversible photothermal response according to claim 1, wherein the method comprises the following steps:

the preparation method of the cross-linking agent comprises the following steps:

(1) Uniformly mixing hydroquinone and p-hydroxybenzoic acid, heating and stirring under the protection of nitrogen, and obtaining a cross-linking agent precursor through suction filtration and recrystallization;

(2) Dissolving the cross-linking agent precursor in the step (1) with bromohydrin, anhydrous potassium carbonate and tetrabutylammonium bromide in an organic solvent, carrying out reflux reaction under the protection of nitrogen, and purifying the obtained crude product through column chromatography to obtain a cross-linking agent intermediate;

(3) And (3) dissolving the cross-linking agent intermediate in the step (2) with EDC, DMAP, triethylamine and thiooctanoic acid in an organic solvent, reacting at room temperature under the protection of nitrogen, and purifying the obtained crude product by column chromatography to obtain the cross-linking agent.

4. An adhesive with reversible photothermal response, which is characterized in that: a prepared by the method of any one of claims 1-3.

5. Use of the reversible photothermal responsive adhesive of claim 4 for the preparation of a reversible photosensitive adhesive.

6. A method of verifying the performance of a reversible photothermal responsive adhesive as defined in claim 4, wherein: the reversible photothermal response verification steps are as follows: the glass plate is used as a matrix, the polymer adhesive is arranged in the middle of the glass plate, the adhesion is carried out by initial heating and solidification, ultraviolet irradiation and secondary solidification and adhesion after debonding, and heating and self-repairing solidification and adhesion after scraping, and the adhesion strength under the state of three different adhesion modes is tested and compared by a tension machine.