CN115368561B

CN115368561B - Eutectic supermolecular gel and its prepn and application

Info

Publication number: CN115368561B
Application number: CN202210899085.6A
Authority: CN
Inventors: 许泽军; 陈苏芳; 荆依亭; 张道洪
Original assignee: South Central University for Nationalities
Current assignee: South Central Minzu University
Priority date: 2022-07-28
Filing date: 2022-07-28
Publication date: 2023-10-13
Anticipated expiration: 2042-07-28
Also published as: CN115368561A

Abstract

The invention discloses eutectic supermolecule gel. The eutectic supermolecular gel is prepared from aqueous solution of tannic acid and aqueous solution of amino-terminated hyperbranched polymer. The invention also discloses a preparation method and application of the eutectic supermolecule gel. The eutectic supermolecular gel disclosed by the invention does not contain an organic solvent, is nontoxic and pollution-free, is easy to clean, simple in preparation method, mild in reaction condition, strong in binding force as an adhesive, suitable for binding of various materials, recyclable, and capable of still having a binding effect under adverse environmental conditions such as low temperature, strong acid, strong alkali and the like.

Description

Eutectic supermolecular gel and its prepn and application

Technical Field

The invention belongs to the technical field of adhesives, and particularly relates to eutectic supermolecular gel and a preparation method and application thereof.

Background

Along with the development of economy and society, the adhesive is gradually blended into the aspects of human life, is small enough to bond stamps and shoes and is large enough to bond fuselages and wings, and the adhesive is not available in the fields of industry, agriculture, traffic, medical treatment and national defense. Adhesive materials play an important role in life, scientific research and industry. Most of the natural adhesives have been replaced by industrial adhesives.

The hyperbranched polymer is also called hyperbranched polymer and hyperbranched polymer, and has the characteristics of high viscosity, low fluidity, easy film formation, difficult crystallization and the like. Compared with high molecular polymers, hyperbranched polymers have many physical, chemical and mechanical properties because of various non-covalent interactions in the hyperbranched system, such as hydrogen bonds, coordination bonds, and host-guest recognition. In recent years, the design and function of supramolecular polymer materials has been of interest. The hyperbranched polymer not only has the excellent characteristic of a linear polymer, but also is simple to prepare and low in cost, can be modified according to different requirements, and has great industrial application potential. And the macrocyclic supramolecular polymer is used as an important component of a supramolecular polymer system, and has wide prospect in the aspect of preparing advanced functional materials. Currently, in the development based on macrocyclic supramolecular polymers, the supramolecular polymer solutions or gels are mainly studied with little research in the bulk phase. Moreover, the use of solvents to prepare or process supramolecular polymers greatly reduces the stability and processability of the materials, limiting the practical application of supramolecular polymers, and most industrial adhesives contain organic solvents, which are not only toxic but also not easy to clean. Therefore, the development of solvent-free supramolecular adhesives is of great importance for the development of supramolecular chemistry. The invention provides an adhesive which is nontoxic, easy to clean, and reusable, and which is free of organic solvents, and which can maintain its own tackiness under low temperature conditions.

Disclosure of Invention

The first technical problem to be solved by the invention is to provide a eutectic supramolecular gel which is used as an adhesive, does not contain organic solvents, is nontoxic and tasteless, is easy to clean, and can still have adhesiveness at low temperature.

The second technical problem to be solved by the invention is to provide a preparation method of the eutectic supramolecular gel.

In order to solve the first technical problem, the technical scheme provided by the invention is as follows:

a eutectic supramolecular gel is prepared from an aqueous solution of an amino-terminated hyperbranched polymer and an aqueous solution of tannic acid.

The tannic acid has the following structural formula:

the amino-terminated hyperbranched polymer is amino-terminated Hyperbranched Polyamidoamine (HPAMAM), and the HPAMAM has the following structural formula:

according to the scheme, the molar ratio of the amino-terminated hyperbranched polymer to the tannic acid is 1:0.6 to 1.25.

In order to solve the second technical problem, the technical scheme designed by the invention comprises the following steps:

1) Respectively weighing amino-terminated hyperbranched polymer and tannic acid;

2) Respectively preparing the weighed amino-terminated hyperbranched polymer and tannic acid into aqueous solution;

3) Adding the amino-terminated hyperbranched polymer aqueous solution obtained in the step 2) into a tannic acid aqueous solution to generate floccules, heating and drying until the floccules disappear, and cooling to room temperature to obtain the eutectic supermolecule gel.

According to the scheme, the preparation of the aqueous solution in the step 2) is carried out under stirring, and the temperature of the system is controlled to be 20-50 ℃.

According to the scheme, the stirring time in the step 2) is 1-5 h.

According to the scheme, the mass ratio of the amino-terminated hyperbranched polymer to water in the step 2) is 5-30%.

According to the scheme, the drying temperature in the step 3) is 60-120 ℃ and the drying time is 6-50 h.

The invention also provides application of the eutectic supermolecule gel as a low-temperature adhesive. The eutectic supermolecular gel is used as an adhesive, is suitable for common base materials such as wood, glass, ceramics, iron sheets, steel sheets and the like, is particularly outstanding in the aspect of bonding glass, and still has bonding effect under the condition of low temperature (-60 ℃).

According to the invention, through controlling the feeding ratio of amino-terminated hyperbranched polymer to tannic acid, a one-step method is adopted to mix, heat and stir Tannic Acid (TA) monomer containing a large number of hydroxyl groups and amino-terminated Hyperbranched Polyamidoamine (HPAMAM), a dense hydrogen bond network system is formed between hydroxyl groups on tannic acid and amino groups or amide bonds on the amino-terminated hyperbranched polyamidoamine, so that the X-TA-HPAMAM adhesive is prepared, namely tannic acid is used as a hydrogen bond donor, HPAMAM is used as a hydrogen bond acceptor, water is used as a solvent, and the tannic acid and the HPAMAM are stirred until the tannic acid and the HPAMAM are completely dissolved to form a transparent solution, and the transparent solution is mixed until the system becomes jelly, and heated until all unbound water is evaporated to completely obtain the supermolecular gel containing a large number of hydrogen bonds. The supermolecular gel does not contain organic solvent and toxic gas, and the bonding principle is mainly that the bonding property of the supermolecular gel under the room temperature condition is maintained by utilizing hydrogen bonds formed between amino-terminated hyperbranched polymer and tannic acid. The supermolecular gel has certain bonding effect on different materials (glass, wood board, steel, iron sheet, copper sheet, etc.), such as a large number of hydroxyl groups contained on the surface of the glass, a large number of fluorine ions contained on the surface of polytetrafluoroethylene can form a rich hydrogen bond network system with hydrogen bonds of the supermolecular polymer gel material, and the hydrogen bonds can be reformed after being broken in the heating temperature-raising and cooling process, so that the reversibility of the hydrogen bonds endows the supermolecular gel with the characteristic of reutilization.

The invention has the beneficial effects that: 1. the supermolecular gel based on the amino-terminated hyperbranched polymer and the tannic acid provided by the invention does not contain an organic solvent, is nontoxic and pollution-free, is easy to clean, has strong binding power as an adhesive, is suitable for binding various materials, can be recycled and reused, still has a binding effect under the adverse environmental conditions of low temperature, strong acid, strong alkali and the like, and has great market application prospect. 2. The amino-terminated hyperbranched polymer and tannic acid eutectic supermolecular gel prepared by the invention has the advantages of simple preparation method, mild reaction conditions, no use of any organic solvent in the preparation process, no generation of toxic and harmful wastes, environmental protection, economy and practicability, and contribution to realization of industrial production.

Drawings

FIG. 1 is a photograph of a process for preparing a eutectic supramolecular gel according to example 1 of the present invention.

FIG. 2 is an infrared spectrum of the starting material (TA, HPAMAM) and the product (0.6-TA-HPAMAM) of example 1.

FIG. 3 is a photograph of a drawing of the eutectic supramolecular gel 0.6-TA-HPAMAM prepared in example 1 on a glass plate.

FIG. 4 is a tensile test chart of the eutectic supramolecular gel X-TA-HPAMAM prepared in examples 1 and 2.

FIG. 5 is a graph of macroscopic tensile testing of 0.6-TA-HPAMAM on various substrates for the eutectic supramolecular gel prepared in example 1.

FIG. 6 is a drawing showing the tensile test of 0.6-TA-HPAMAM on various substrates for the eutectic supramolecular gel prepared in example 1.

FIG. 7 is a dynamic temperature scanning rheological test chart of 0.6-TA-HPAMAM for the eutectic supramolecular gel prepared in example 1.

FIG. 8 is a drawing showing the tensile test of 0.6-TA-HPAMAM in eutectic supramolecular gel prepared in example 1 at different temperatures on the glass surface.

FIG. 9 is a graph showing tensile testing of the 0.6-TA-HPAMAM eutectic supramolecular gel prepared in example 1 for cyclic use at different temperatures on the glass surface.

FIG. 10 is a water-proof repair chart of 0.6-TA-HPAMAM of the eutectic supramolecular gel prepared in example 1.

Detailed Description

The present invention will be described in further detail below with reference to the drawings and specific embodiments for better understanding of the technical solutions of the present invention to those skilled in the art.

Example 1

The preparation method of the eutectic supermolecular gel comprises the following specific steps:

1.02g of Tannic Acid (TA) and 2.40g of amine-terminated hyperbranched polyamidoamine (HPAMAM, molecular weight 4770) were placed in 50mL beakers, respectively, and ultrapure water was added thereto, and the mixture was completely dissolved at room temperature to prepare an aqueous amine-terminated hyperbranched polymer solution and an aqueous tannic acid solution, each of which was 10%. Slowly adding tannic acid water solution into amino-terminated hyperbranched polymer water solution to generate floccule, then placing into an oven at 80 ℃ for heating until floccule disappears, and cooling to room temperature to obtain eutectic supermolecular gel (0.6-TA-HPAMAM).

The procedure of this example is shown in FIG. 1, and it is clear from FIG. 1 that the transition from floc generation (left hand beaker) upon heating and cooling to gel (middle inverted beaker) finally gives a transparent gel-like eutectic supramolecular gel (0.6-TA-HPAMAM) at room temperature.

The eutectic supramolecular gel prepared in this example was subjected to infrared testing with TA and HPAMAMThe characteristic peaks of the amino-terminated hyperbranched polyamidoamine HPAMAM are compared, the infrared spectrum is shown in figure 2, and 3500-3000cm in the infrared spectrum of TA ^-1 Strong absorption band attributed to-OH group, 1704cm ^-1 Is attributable to C=O stretching vibration of ester group, 1442cm ^-1 The absorption band of (a) can be attributed to stretching of aromatic bonds C=C-C, 1093cm ^-1 Attributable to the C-O bond, at 765cm ^-1 An absorption vibration peak of c=c in the benzene ring was observed; the results of the infrared spectrum of HPAMAM-4 showed that: 3275cm ^-1 Vibration peak ascribed to N-H group, 2931cm ^-1 And 2828cm ^-1 Vibration peak attributed to C-H group, 1647cm ^-1 The strong absorption peak is attributed to the absorption peak of C=O, 1558cm ^-1 Absorption peaks ascribed to C-N groups. In the infrared spectrum of TA-HPAMAM, the vibration peak of C=O compared with HPAMAM is composed of 1647cm ^-1 Offset to 1630cm ^-1 The method has the following steps: of TA-OH and HP-NH ₂ Hydrogen bonds are formed between the two; at 1338cm ^-1 New peaks appear at the sites, also indicating the-OH of TA and-NH of HPAMM ₂ Hydrogen bond interaction exists between the two materials and a compact hydrogen bond network system is formed, so that eutectic supermolecular gel (0.6-TA-HPAMAM) which can be used as an adhesive is successfully constructed.

Example 2

As in example 1, only the ratio of TA to HPAMAM was varied to prepare a different eutectic supramolecular gel of 4 (X-TA-HPAMAM, hereafter also written as adhesive, where X represents the amount of 0.5 TA per HPAMM, in the specific examples of the invention X represents the mmol of TA and the amount of HPAMM is fixed at 0.5 mmol). The molar ratios of tannic acid and terminal amino hyperbranched are shown in Table 1 (wherein 0.6-TA-HPAMAM is prepared as in example 1).

TABLE 1 proportions of the various components of X-TA-HPAMAM

The adhesive prepared in this embodiment is transient for bonding a wide variety of materials, such as glass sheets, iron sheets, copper sheets, and the like. Taking a glass sheet as an example, the adhesive prepared in the embodiment 1 is uniformly coated on the glass sheet, pressed for 30 seconds, and pulled apart, so that the wire drawing condition between the two glass sheets can be clearly seen, as shown in fig. 3.

The adhesive X-TA-HPAMM prepared in this example was used to perform an adhesion test on glass sheet materials according to part 6 of the method for testing fatigue Property of Polymer-based composite according to GB/T35465.6-2020: adhesive tensile shear fatigue is used for preparing a spline, after an adhesive is coated on one substrate, the other same substrate is adhered together in the opposite direction, and the spline is placed in an oven at 80 ℃ for heating for 1h and cooled to room temperature for tensile test. The tensile test of glass bars of different proportions showed different bonding effects, and the results are shown in fig. 4. As can be seen from the test results, the bonding effect of 0.4-TA-HPAMM on the glass plate was 1.71MPa, 0.5-TA-HPAMM was 2.06MPa, 0.6-TA-HPAMM was 3.95MPa, 0.7-TA-HPAMM was 2.87MPa, and 0.8-TA-HPAMM was 2.57MPa, which was the best bonding effect when the mole number of tannic acid was 0.6 mole (0.6-TA-HPAMM).

In order to better test the bonding performance of the adhesive prepared in the embodiment between copper sheets, iron sheets, glass sheets, polytetrafluoroethylene and the like, macroscopic tensile test is carried out on bonded sample bars at room temperature, as shown in fig. 5, it can be seen that 0.6-TA-HPAMA has bonding effect on different base materials such as copper sheets, glass sheets, iron sheets, polytetrafluoroethylene and the like. 20mg of 0.6-TA-HPAMAM was applied to each of the adhesive areas of 2.5X2.5 mm ² The copper sheet (figure 5 a) and the glass sheet (figure 5 b) are not de-bonded when a weight of 10kg is hung on the copper sheet; the coating was applied to an iron sheet (FIG. 5 c) and a polytetrafluoroethylene sheet (FIG. 5 d) having a bonding area of 5mm X1 mm, and weights of 5kg and 3kg were hung, respectively, without any sign of sliding between the substrates. Indicating that 0.6-TA-HPAMAM has higher bonding strength for different substrates.

According to GB/T35465.6-2020 part 6 of the fatigue property test method of polymer matrix composite materials: the adhesive tensile shear fatigue was tested by stretching the sample bars of different substrates on a universal material tester, and the results are shown in fig. 6, which shows that the adhesive prepared in this example has an adhesive effect on most materials. The bonding strength of the supermolecule adhesive 0.6-TA-HPAMAM on the steel sheet is 1.87MPa, the bonding strength on the aluminum sheet is 1.99MPa, the bonding strength on the wood board is 2.47MPa, the bonding strength on the iron sheet is 2.52MPa, and the bonding strength on the glass is 3.95MPa. The 0.6-TA-HPAMM has the greatest bonding strength on the glass sheet because the glass surface contains multiple hydroxyl groups to form hydrogen bonds with the material.

The adhesive prepared in this example 1 was subjected to rheological testing on a rotary rheometer of the DHR-1 type, TA instruments, usa, and it can be seen that the viscosity gradually decreases with increasing temperature by flow-temperature scanning as shown in fig. 7. As the hydrogen bond is broken by the temperature rise, the bonding effect becomes poor, and when the temperature becomes room temperature, the hydrogen bond is formed again, as with the rheological result.

The present invention also explores the bonding effect of the adhesive prepared in example 1 at low temperature, taking glass substrates as an example. The bonding effect is reduced but still has bonding effect when the temperature is lower than 0 ℃, and the result is shown in figure 8, and the fact that the bonding strength reaches 4.26MPa at most when the temperature is 10 ℃, and the bonding strength of 0.6-TA-HPAMM is reduced when the temperature is increased, and the bonding strength is reduced due to the fact that hydrogen bonds are broken when the temperature is increased, which is consistent with the conclusion of dynamic temperature scanning of the material. When the temperature is lower than 10 ℃, the bonding strength gradually decreases along with the decrease of the temperature, the bonding strength is 3.33MPa at 0 ℃, the bonding strength is 3.15MPa at-10 ℃, the bonding strength is 2.78MPa at-20 ℃, the bonding strength is 2.54MPa at-30 ℃, the bonding strength can still reach 2.37MPa at-60 ℃, the material can be used at normal temperature, has a stronger bonding effect at low temperature, and fully proves the feasibility of the 0.6-TA-HPAMM as an anti-freezing adhesive.

The adhesive prepared in this example 1 was tested for its recycling properties, and after the glass strips were pulled apart, the sample remained adhered to the glass plate, and after the glass strips were pulled apart for the first time, the supramolecular adhesive remained adhered to the glass plate, and then the two glass plates were pressed for 10 seconds, heated in an oven at 80 ℃ for one hour, and cooled to room temperature for direct use in the cyclic tensile test. As can be seen from FIG. 9, the 0.6-TA-HPAMAM adhesive strength of the materials at different temperatures can be recycled, although they are different. The bonding strength is reduced slightly after three times of circulation, but still has better bonding strength. The 0.6-TA-HPAMM can be recycled, and the glass plates are adhered again due to the fact that the hydrogen bond is reversible, and the stretching external force breaks the hydrogen bond, but cools to room temperature after heating, and the hydrogen bond is formed again, so that the excellent adhesive property is shown.

The room temperature repair properties of the adhesive prepared in this example 1 were also explored in the present invention, as shown in fig. 10. Firstly, making a round hole in the centrifuge tube, and pouring water into the centrifuge tube. After water flows out from the holes, the material 0.6-TA-HPAMM is directly smeared on the damaged position of the centrifuge tube in the air, water is continuously added, and the holes of the centrifuge tube are found to be well sealed, so that water leakage is completely prevented. It is illustrated that, in contrast to the adhesives reported heretofore, 0.6-TA-HPAMAM is a fast setting and water resistant adhesive and does not require cumbersome heating processes.

Claims

1. The eutectic supermolecular gel is characterized by being prepared from an aqueous solution of tannic acid and an aqueous solution of an amino-terminated hyperbranched polymer, wherein the amino-terminated hyperbranched polymer is amino-terminated hyperbranched polyamide amine, and the amino-terminated hyperbranched polyamide amine has the following structural formula:

2. the eutectic supramolecular gel of claim 1, wherein the molar ratio of amino-terminated hyperbranched polymer to tannic acid is 1:0.6 to 1.25.

3. A method of preparing a eutectic supramolecular gel according to any one of claims 1 to 2, comprising the steps of:

3) Adding the amino-terminated hyperbranched polymer aqueous solution into the tannic acid aqueous solution to generate floccules, heating and drying until the floccules disappear, and finally cooling to room temperature to obtain the eutectic supramolecular gel.

4. A method for preparing a eutectic supramolecular gel according to claim 3, wherein the step 2) of preparing an aqueous solution is performed under stirring, and the temperature of the system is controlled to be 20-50 ℃ during stirring.

5. The method for preparing a eutectic supramolecular gel according to claim 4, wherein the stirring time of step 2) is 1-5 h.

6. The method for preparing a eutectic supramolecular gel according to claim 3, 4 or 5, wherein the mass ratio of the amino-terminated hyperbranched polymer to water in the aqueous solution of the amino-terminated hyperbranched polymer in step 2) is 5% -30%.

7. The method for preparing a eutectic supramolecular gel according to claim 3, 4 or 5, wherein the drying temperature of step 3) is 60-120 ℃ and the drying time is 6-50 h.

8. Use of the eutectic supramolecular gel according to any one of claims 1 to 2 as a low temperature adhesive, said low temperature being-60 to 25 ℃.

9. The use according to claim 8, wherein the substrate to which the adhesive is bonded is glass, wood, steel, iron or copper.