Dual-function adhesive for aluminum hydride, manufacturing method and application

Abstract

The present invention provides a dual-function adhesive for aluminum hydride, its manufacturing method and application, and the structural formula of this adhesive is as follows: [Formula 1] JPEG2026502837000015.jpg78166The adhesive of the present invention is a new adhesive material with dual functions. At an addition amount of 0.5 wt%, it has excellent coating effect on α-AlH3, reducing the electrostatic sensitivity of α-AlH3 by more than 80% and significantly reducing the moisture absorption of α-AlH3. Meanwhile, the new adhesive material with dual functions of the present invention has the effect of intuitive coating uniformity, allowing the reaction progress to be monitored in real time, greatly improving the efficiency of α-AlH3 coating experiments.

Description

[Technical Field]

[0001] The present invention belongs to the technical field of energy-containing materials and relates to an adhesive, in particular an adhesive with dual functions for aluminum hydride, its manufacturing method and application. [Background technology]

[0002] Solid rocket engines are the power systems for various advanced strategic and tactical missiles. Solid propellant technology is both the core and foundational technology of solid rocket engines, and plays a key role in improving missile payload and miniaturization. In terms of the performance of solid propellants, high energy performance is a constant goal pursued by researchers and the driving force behind the advancement of solid propellants. To improve the energy performance of solid propellants, researchers are developing and using energy-containing adhesives and plasticizers, high-energy-density oxidizers, and new fuels. In the development of new fuels, Finholt first synthesized AlH3 in 1947 by reacting LiH with AlCl3 in a diethyl ether solution. To date, seven crystal forms have been identified, of which α-AlH3 is the most stable, with a standard molar enthalpy of formation of -11.8 kJ / mol and an absolute entropy of 30.0 kJ·mol -1 °C, the standard molar Gibbs free energy of formation is 45.4 kJ / mol, the relative molecular mass is 30.0, and the density is 1.489 g / cm 3It has a hydrogen content of 10.08% and a hydrogen storage density of 148 g / L, twice that of liquid hydrogen. Since its first synthesis, α-AlH3 has been considered an ideal fuel for new-generation solid propellants due to its high hydrogen content, small molecular weight of combustion products, and relatively high thermal decomposition temperature. It has been used to improve the energy performance of solid propellants. Solid propellants based on α-AlH3 significantly improve the combustion performance of α-AlH3-based propellants compared to Al-based propellants, with the heat of combustion being 1.5 times higher than that of Al-based propellants and the maximum combustion temperature being approximately 200°C higher. For a given content of other components in the solid propellant, the theoretical specific impulse of the propellant increases with the amount of Al powder substituted with α-AlH3. When 1% by mass of Al powder was replaced with AlH3, the theoretical specific impulse of the propellant increased by approximately 0.64 s. After 18% of the Al was replaced with α-AlH3, the theoretical specific impulse of the propellant reached 281.72 s, an improvement of 11.31 s over the theoretical specific impulse of the all-Al propellant. Therefore, α-AlH3 is expected to be the most promising high-energy fuel in the propellant field. Furthermore, as a high-energy combustion component of solid propellants, α-AlH3 can effectively improve the theoretical specific impulse of the propellant, making it one of the preferred components for next-generation solid propellants.

[0003] However, α-AlH3 poses several problems, including its susceptibility to oxidation, poor chemical and thermal stability, dangerous manufacturing and storage, and a tendency to malfunction. Research has shown that when α-AlH3 is stored at room temperature for 14 days, a scaly oxide layer gradually forms on the surface, causing hydrogen gas to desorb. Humidity accelerates the decomposition of α-AlH3, resulting in hydrogen pressure, voids, and wrinkles within the propellant, resulting in a slower combustion rate. Furthermore, during its accelerated decomposition, α-AlH3 acts as a reducing agent, affecting other components of the solid propellant and resulting in poor compatibility with the main components of the solid propellant, significantly limiting its use in solid propellants. The decomposition mechanism of α-AlH3 has also been investigated. Sinke et al. performed theoretical calculations and found that at 298 K, the average enthalpy of formation of α-AlH3 was -11.4±0.8 kJ / mol, the absolute entropy was 30.0±0.4 kJ / mol, and the Gibbs energy of formation was 45.4±1.0 kJ / mol. This indicates that the thermodynamic state of α-AlH3 is unstable and that it can spontaneously decompose into Al and H2. According to the report, the isothermal thermal decomposition curve of α-AlH3 exhibits an S-shape and can be divided into three main stages: an induction period (during which hydrogen release is slow and aluminum nuclei grow; this is the rate-limiting step); an acceleration period (when the hydrogen release rate increases, reaching 60%, and numerous voids are observed within the crystal); and a decline period (when hydrogen release from the interior of α-AlH3 continues until the decomposition to aluminum is complete). Therefore, it can be concluded that the key to inhibiting the decomposition of α-AlH3 is to suppress the occurrence of the induction period.

[0004] These studies have demonstrated that improving the stability of α-AlH3 is of great significance for the development of propellants. Currently, the main methods for improving the stability of α-AlH3 include surface treatment, coating, and low-temperature storage. Coating not only effectively improves the stability of α-AlH3 but also prevents direct contact between α-AlH3 and other components in solid propellants, fully addressing the anticipated "induction period" problem. Coating of energy-bearing materials has been an active area of ​​research in recent years. In 2011, Qiu H. et al. used a spray-drying method to coat RDX with 17% by weight of PVAc and VMCC, significantly reducing the impact sensitivity of RDX (Qiu H. et al. J. Hazard. Mater., 2011, 185, 489-493). In 2016, Wang J. et al. used a water suspension method to coat HMX with 25% by mass of graphene and other coating agents, significantly reducing the friction sensitivity of HMX (Wang J. et al. J. Energ. Mater., 2016, 34, 235-245). In 2019, Zhou X. et al. used a vapor deposition method to coat RDX with 54% CuO, achieving a relatively good coating effect (Zhou X. et al. Propellants Explos. Pyrotech., 2019, 44, 1368-1374). Cai X. et al. used fluorine-containing rubber FE 26 as a coating agent and liquid CO2 as a poor solvent and dispersion medium to achieve physical coating of α-AlH3 using supercritical fluid technology. They found that the enthalpy of formation of the coated sample increased, the thermal stability improved, the sensitivity to electric sparks decreased, and the surface became smoother (Cai X. et al. Propellants, Explosives, Pyrotechnics, 2015, 40(6), 914-919). Li Lei et al. found that coating α-AlH3 with graphene oxide using a solvent-poor solvent method effectively reduced the mechanical impact sensitivity of α-AlH3 (Li Lei, Gu Jian, Huang Danzhuan et al. Solid Rocket Technology, 2019, 42(1), 66-71). Research has shown that α-AlH3 has slightly lower or no higher friction and impact sensitivity than HMX, but has a very high electrostatic sensitivity, which has consequently severely limited its application research in the propellant field.To address the above issues, Qin Mingna et al. used a solvent-antisolvent method to coat AlH3 with stearic acid, effectively reducing the electrostatic sensitivity of AlH3 (Qin Mingna et al. Energy-containing Materials, 2017, 25(1), 59-62).

[0005] However, the AlH3 coating solution reported in the above literature has the following three problems: (1) Coating method: The solutions used in the above-mentioned literature, such as spray drying, water suspension, vapor deposition, and solvent-antisolvent methods, achieve excellent coating effects on the energy-bearing materials to be coated. However, they still have the disadvantage of complicated reaction processes and high requirements for experimental equipment. (2) High amount of coating material: The coating materials used have the disadvantage of requiring a large amount of material. After the coating of the energy-bearing material is completed, the sensitivity of the energy-bearing material is reduced to a certain extent, but this also has a significant impact on the energy performance of the energy-bearing sample after coating is complete. (3) Method for detecting the uniformity of the coated product: In the above-mentioned literature, the detection of the coating uniformity after the coating of the energy-bearing material is still required to use a scanning electron microscope. This requires time and effort, and the uniformity of the sample can only be detected after the reaction is completed, making it impossible to intuitively monitor the progress of the coating reaction in real time. Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a dual-function adhesive for aluminum hydride, a manufacturing method and application thereof, which can solve the problem that it is difficult in the prior art to simultaneously achieve the dual functions of moisture absorption prevention and intuitive detection of coating uniformity with a single adhesive. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention is realized by the following technical solutions.

[0008] An adhesive characterized by having the following structural formula: [ka] [In the formula, X is an integer of 5 to 20.]

[0009] Preferably, X is an integer of 6 to 10.

[0010] The present invention further has the following technical features.

[0011] The present invention further provides a method for producing the above adhesive, comprising the steps of: First step: Synthesis of solid-state fluorescent probes with high fluorescence quantum yield The solid-state fluorescent probe with high fluorescence quantum yield is MOF808@7-hydroxy-C-coumarin (7-Hydroxy-Carbocoumarin). 7-Hydroxy-C-coumarin and MOF-808 were weighed and added to a reaction flask containing methanol, and the mixture was left standing for 3 days. After the reaction was completed, the filtrate was removed using a funnel, and the resulting solid material was repeatedly washed with methanol. The resulting MOF808@7-hydroxy-C-coumarin was then dried at room temperature. Second step: Synthesis of adhesive molecules containing three thermosetting groups At 0°C, 1-(6-cyanohexyl)-3-(6-isocyanatohexyl)urea is dissolved in THF, and then dilute hydrochloric acid is added to the reaction solution. The temperature is gradually raised to 80°C and the mixture is stirred. After the reaction is complete, the mixture is concentrated to obtain an adhesive molecule containing three thermosetting groups. Third step: Incorporation of solid-state fluorescent probes into adhesive molecules Adhesive molecules containing three thermosetting groups were weighed and dissolved in 1,2-dichloroethane solvent. M OF808@7-hydroxy-C-coumarin is added to the reaction solution, and dibutyltin dilaurate is then added dropwise, followed by stirring at room temperature to produce an adhesive. The molar ratio of the adhesive molecule containing three thermosetting groups to MOF808@7-hydroxy-C-coumarin is 1:1.

[0012] Preferably, the method comprises the following steps: First step: Synthesis of solid-state fluorescent probes with high fluorescence quantum yield The solid-state fluorescent probe with high fluorescence quantum yield is MOF808@7-hydroxy-C-coumarin. 15.0 g of 7-hydroxy-C-coumarin and 5.0 g of MOF-808 were weighed and added to a reaction flask containing 50 mL of methanol. The mixture was left standing for 3 days. After the reaction was completed, the filtrate was removed using a funnel. The resulting solid material was washed repeatedly with methanol 8-10 times, and the resulting MOF-808@7-hydroxy-C-coumarin was dried at room temperature. Second step: Synthesis of adhesive molecules containing three thermosetting groups At 0°C, 25.0 g of 1-(6-cyanohexyl)-3-(6-isocyanatohexyl)urea was dissolved in 100 mL of THF, and then 1 drop of dilute hydrochloric acid was added to the reaction solution. The temperature was gradually raised to 80°C and the mixture was stirred for 3.0 hours. After the reaction was completed, the mixture was concentrated to obtain an adhesive molecule containing three thermosetting groups. Third step: Incorporation of solid-state fluorescent probes into adhesive molecules 5.0 g of adhesive molecules containing three thermosetting groups was weighed and dissolved in 50.0 mL of 1,2-dichloroethane solvent. Then, 1.625 g of MOF808@7-hydroxy-C-coumarin was added to the reaction solution, and three drops of dibutyltin dilaurate were added dropwise. The mixture was stirred at room temperature for 6.0 hours to produce the adhesive.

[0013] The present invention further provides the use of the above adhesive to combine the dual functions of moisture protection and intuitive detection of coating uniformity for aluminum hydride.

[0014] Preferably, the amount of the adhesive added is 0.5% by weight of the amount of aluminum hydride used.

[0015] Preferably, the adhesive is coated onto aluminum hydride by an in-situ polymerization coating method to obtain a coated product.

[0016] Preferably, the contact angle of the coated product is 88°.

[0017] More specifically, the specific process of the coating is as follows: First step: A trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether is dissolved in 1,2-dichloroethane to prepare a trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether solution. Second step: First, the adhesive is diluted with 1,2-dichloroethane solvent, and then a weighed amount of α-AlH3 is added to the reaction solution. Next, the trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether solution produced in the first step is added to the reaction solution. Finally, dibutyltin dilaurate is added dropwise, and the mixture is stirred at room temperature. The progress of the coating reaction is monitored in real time using an ultraviolet lamp. Third step: After the coating reaction is completed, the mixture is filtered through a funnel with suction, and the resulting solid is washed with 1,2-dichloroethane and dried to obtain the coated product.

[0018] More specifically, the specific process of the coating is as follows: First step: 5.0 g of trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether was dissolved in 50.0 mL of 1,2-dichloroethane to prepare a trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether solution. Second step: First, 10.0 mL of the adhesive was diluted with 20.0 mL of 1,2-dichloroethane solvent, and then 200.0 g of weighed α-AlH3 was added to the reaction solution. 10.0 mL of the trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether solution produced in the first step was then added to the reaction solution. Finally, one drop of dibutyltin dilaurate was added, and the mixture was stirred at room temperature for 3.0 hours. The progress of the coating reaction was monitored in real time using an ultraviolet lamp. Third step: After the coating reaction is completed, the mixture is filtered with suction using a funnel, and the resulting solid is washed with 1,2-dichloroethane 3-5 times and dried to obtain the coated product. [Effects of the Invention]

[0019] Compared with the prior art, the present invention has the following technical advantages. (I) The adhesive of the present invention is a new adhesive material with dual functions. At an additive amount of 0.5 wt%, it has an excellent coating effect on α-AlH3, reducing the electrostatic sensitivity of α-AlH3 by more than 80% and significantly reducing the moisture absorption of α-AlH3. Meanwhile, the new adhesive material with dual functions of the present invention has the effect of intuitive coating uniformity, allowing the reaction progress to be monitored in real time, greatly improving the efficiency of α-AlH3 coating experiments. (II) The adhesive of the present invention contains three thermosetting groups, and even if one group is replaced with a solid fluorescent probe, the cure crosslinking rate and crosslink density are not significantly affected. The polyurethane elastomer produced using the adhesive of the present invention as a raw material has a maximum tensile strength of 4.23 MPa and a breaking elongation of 355%. (III) The adhesive of the present invention contains a solid fluorescent group, and under irradiation with a 365 nm ultraviolet lamp, the distribution area of ​​the adhesive can be intuitively observed, which allows intuitive detection of the coating uniformity and real-time detection of the progress of the coating reaction. (IV) In the present invention, a coating amount of 0.5 wt % exhibits a relatively excellent coating effect on α-AlH3 (as confirmed by intuitive detection or scanning electron microscope), and almost completely eliminates the influence of α-AlH3 on electrostatic spark sensitivity. (V) The adhesive of the present invention coats α-AlH3 using an in-situ polymerization coating method, and after coating is complete, the contact angle of α-AlH3 increases from 18° (highly hygroscopic) before coating to 88° (close to 90°, almost hydrophobic). This characteristic is advantageous for the long-term storage and application of α-AlH3. (VI) After being made into an elastomer, the adhesive of the present invention has a tensile strength of 4.23 MPa and an elongation of 355%, and thus has relatively excellent mechanical properties. (VII) After coating is completed, the thermal decomposition peak temperature of the α-AlH3 of the present invention increases by approximately 4.1°C, further improving the heat resistance of α-AlH3. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a DSC spectrum of the adhesive of Example 1. [Figure 2] FIG. 10 is a diagram showing the contact angles before and after coating with α-AlH 3 in Example 2. [Figure 3] FIG. 10 is a diagram showing the moisture absorption performance before and after coating with α-AlH 3 at room temperature and various humidity conditions in Example 2. [Figure 4] FIG. 10 is a diagram showing the moisture absorption performance before and after coating with α-AlH 3 at room temperature and 75% humidity in Example 2. [Figure 5] FIG. 10 is a mapping diagram after completion of α-AlH3 coating in Example 2. [Figure 6] FIG. 10 is an intuitive detection diagram of the uniformity after coating of α-AlH3 in Example 2. [Figure 7] 1A and 1B are scanning electron microscope images of Example 2 before and after coating with α-AlH3. [Figure 8] FIG. 1 is a comparative DSC chart of Example 2 before and after coating with α-AlH3. [Figure 9] FIG. 1 is a scanning electron microscope image of Comparative Example 1 after coating with α-AlH3. [Figure 10] FIG. 10 is another scanning electron microscope image of Comparative Example 1 after coating with α-AlH3. [Figure 11] FIG. 10 is a scanning electron microscope image of Comparative Example 2 after coating with α-AlH3. [Figure 12] FIG. 10 is another scanning electron microscope image of Comparative Example 2 after coating with α-AlH3. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will now be described in more detail with reference to examples.

[0022] Unless otherwise specified, all raw materials used in the present invention are commercially available raw materials known in the prior art. The aluminum hydride is preferably α-AlH3.

[0023] As the 7-hydroxy-C-coumarin, a known 7-hydroxy-C-coumarin was used, such as the 7-hydroxy-C-coumarin disclosed in Dyes and Pigment, 2019, 163, pp. 55-61.

[0024] MOF-808 uses Zr clusters as the coordination metal. It is a metal organic framework , an abbreviation for MOF-808(Zr), with the molecular formula C 24 H 16 O 32 It is Zr6 and has a CAS number of 1579984-19-2.

[0025] In the present invention, MOF808@coumarin refers to MOF808@7-hydroxy-C-coumarin.

[0026] The measuring device of the present invention is as follows. (1) Infrared spectra were measured using a Nexus 870 Fourier transform infrared spectrometer manufactured by Nicolet, USA. (2) Nuclear magnetic resonance (NMR) was measured using an AVANCE AV500 nuclear magnetic resonance spectrometer manufactured by Bruker, Germany. (3) The number average molecular weight was measured using a GPC-50 gel permeation chromatograph manufactured by PL Ltd., UK. (4) The mechanical properties of the elastomers were measured using an Instron 4505 universal material testing machine manufactured by Instron Corporation, USA. (5) Electrostatic sensitivity was measured using a JGY-50III(J) type electrostatic sensitivity measuring instrument. (6) Solid-state fluorescence quantum yields were measured on an Edinburgh FLS980 fluorescence spectrometer. (7) X-ray photoelectron spectroscopy was performed using a K-Alpha XPS instrument manufactured by Thermo Scientific, USA. (8) Viscosity was measured using a cone-plate viscometer manufactured by Bruker, Germany. (9) DSC was measured using a DSC-2910 differential scanning calorimeter manufactured by TA Corporation, USA.

[0027] The technical concept of the present invention is as follows. First, this invention employs in-situ polymerization to coat α-AlH3. In-situ polymerization uses a prepolymer as the shell layer material, and the polymer improves particle stability and compatibility while retaining the properties of the material itself, allowing for the grafting of functional groups. Among various polymer coating methods, in-situ polymerization produces polymer composites by initiating polymerization in a mixed solution of α-AlH3 and polymerizable monomers. This method is simple to produce, has good dispersibility, and allows for effective control of the coating layer thickness, making it a focus of research on polymer-modified composites. Second, the solid fluorescent group functions as a positioning group within the adhesive molecule and serves as a positioning source for intuitive detection of the uniformity of sensitivity reduction due to coating. Therefore, it is introduced into the adhesive molecule by chemical bonding, and the fluorescence quantum yield of the solid fluorescent group is set to 80% or more (the higher the better). Third, the adhesive molecule selected has at least three identical curing groups, and by adjusting the ratio of materials, one of the groups in the adhesive molecule reacts with the solid fluorescent group and couples with it, while the remaining two groups remain free, so that the adhesive exhibits the characteristics of a fast curing and crosslinking speed during the coating process of the energy-containing material and high mechanical strength after the coating and crosslinking are completed. Fourth, the amount of adhesive used in the coating process should be minimized.

[0028] In order to solve the problems of α-AlH3, which requires a large amount of adhesive in the coating process, a slow curing speed, and a time-consuming process for intuitively detecting the coating uniformity, as well as the inability to intuitively detect the progress of the coating reaction, the concept of the present invention is as follows: (1) Selection of solid fluorescent groups The inventors first considered coumarin-based compounds. Coumarin-based compounds are very important natural products, and their skeletons are widely found in drug molecules, cosmetics, and food additives. Furthermore, coumarin-based compounds are often used in small molecule fluorescent probes due to their advantages, such as good biocompatibility, large Stokes shift, and strong and stable fluorescence emission properties. In 2019, Professor Yang Youjun's research group at East China University of Science and Technology first reported 7-hydroxy-C-coumarin. This 7-hydroxy-C-coumarin has superior spectroscopic properties compared to conventional 7-hydroxycoumarin, with a significant red-shift in both UV absorption and fluorescence emission maxima. However, its structural rigidity is so low that its fluorescence quantum yield is significantly limited, significantly limiting its application. Therefore, the inventors considered a solution and found a way to significantly improve the fluorescence quantum yield of 7-hydroxy-C-coumarin while converting its liquid form into a more useful solid form. Our solution is to encapsulate 7-hydroxyspirocoumarin in a MOF cage, restricting the rotation and vibration within the spirocoumarin molecule. This reduces the energy loss of nonradiative transitions and increases the energy of radiative transitions, resulting in an improved fluorescence quantum yield. We conducted our study using MOF808, which has a cavity diameter that matches the size of 7-hydroxyspirocoumarin. Surprisingly, after encapsulating 7-hydroxyspirocoumarin in MOF808, the solid-state fluorescence quantum yield increased to 96%, further validating our hypothesis. (2) Selection of adhesive and introduction of solid-state fluorescent probe The adhesive of choice and the introduction of solid-state fluorescent probes must have two characteristics: <1> The adhesive molecule must have at least three functional groups, so that even if some of the functional groups in the adhesive molecule are substituted, the coating reaction can be completed quickly during the coating process and the thermodynamic performance will not be affected. <2> The functional groups in the adhesive molecules react easily with MOF808, allowing MOF808 to be introduced into the adhesive molecules under mild conditions without significantly affecting the performance of the adhesive. (3) We plan to adopt the concept of in-situ polymerization coating for α-AlH3 coating. The in-situ polymerization method has advantages such as superior coating effect, smaller coating amount, and higher coating strength compared to coating methods such as spray drying, water suspension, vapor phase growth, and solvent-poor solvent methods.

[0029] Therefore, the inventors have decided to select a compound containing a thermosetting group (-NCO) as an adhesive, and a trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether containing a hydroxyl group as a curing agent, and to perform coating and curing molding on α-AlH3.

[0030] The structural formula of the trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether is shown below. [ka]

[0031] In a preferred embodiment of the present invention, a known commercially available trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether is used, and its number average molecular weight is 3,800.

[0032] The mechanism of adhesive curing and coating is as follows. [ka]

[0033] The structural formula of the dual function adhesive for aluminum hydride of the present invention is as follows: [ka]

[0034] A specific synthesis scheme for the method of producing an adhesive having dual functions for aluminum hydride of the present invention is as follows: [ka]

[0035] A specific synthesis scheme of this production method includes the following first to third steps. First step: Synthesis of solid-state fluorescent probes with high fluorescence quantum yield [ka] Second step: Synthesis of adhesive molecules containing three thermosetting groups [ka] Third step: Incorporation of solid-state fluorescent probes into adhesive molecules [ka]

[0036] Note: rear No processing reaction is required, and the adhesive can be prepared just before use, resulting in a dual-function adhesive for aluminum hydride with a yield of 86%.

[0037] Specific examples of the present invention are described below, but the present invention is not limited to the following specific examples, and all equivalent modifications based on the technical solutions of this application are included in the scope of the present invention.

[0038] Example 1: In this example, a method for producing an adhesive was provided, which included the following first to third steps. First step: Synthesis of solid-state fluorescent probes with high fluorescence quantum yield The solid-state fluorescent probe with high fluorescence quantum yield is MOF808@7-hydroxy-C-coumarin. 15.0 g of 7-hydroxy-C-coumarin and 5.0 g of MOF-808 were weighed and added to a reaction flask containing 50 mL of methanol and allowed to stand for 3 days. After the reaction was completed, the filtrate was removed using a funnel. The resulting solid material was washed repeatedly with methanol 8-10 times, and the resulting MOF-808@7-hydroxy-C-coumarin was dried at room temperature. The yield was 91%. After the experimental process was stabilized, it was possible to gradually increase the raw material input by 2 to 3 times, with almost no change in yield. Second step: Synthesis of adhesive molecules containing three thermosetting groups At 0°C, 25.0 g of 1-(6-cyanohexyl)-3-(6-isocyanatohexyl)urea (Compound 1) was dissolved in 100 mL of THF (tetrahydrofuran). One drop of dilute hydrochloric acid was then added to the reaction mixture, which was then gradually heated to 80°C and stirred for 3.0 hours. After the reaction was complete, the mixture was concentrated to obtain an adhesive molecule (Compound 2) containing three thermosetting groups. The yield was 83%. After the experimental process was stabilized, it was possible to gradually increase the raw material input by 2 to 3 times, with almost no change in yield. Third step: Incorporation of solid-state fluorescent probes into adhesive molecules 5.0 g of an adhesive molecule (compound 2) containing three thermosetting groups was weighed and dissolved in 50.0 mL of 1,2-dichloroethane solvent. Then, 1.625 g of MOF808@7-hydroxy-C-coumarin was added to the reaction solution, and three drops (approximately 0.6 mL) of dibutyltin dilaurate (DBTDL) were added dropwise. The mixture was stirred at room temperature for 6.0 hours to produce the adhesive. In this step, the molar ratio of adhesive molecule containing three thermosetting groups (compound 2) to MOF808@7-hydroxy- C -coumarin was 1:1.

[0039] Note: No post-treatment is required; prepare immediately before use. The yield was 86%.

[0040] After the experimental process was stabilized, it was possible to gradually increase the raw material input by 2 to 3 times, with almost no change in yield.

[0041] Structural identification: IR (KBr, cm -1 ): 3276 (-NH, stretching vibration), 2933 (-CH2, antisymmetric stretching vibration), 2852 (-CH2, symmetric stretching vibration), 2258 cm -1 (-NCO stretching vibration peak), 1639 (C=O, stretching vibration), 1493 (-NH, bending vibration), 968 (=CH, out-of-plane bending vibration), 720 (-CH2, in-plane rocking vibration). 1 1 H NMR: It should be noted that the target adhesive molecules prepared in this example are too polar to dissolve in deuterated reagents commonly used in nuclear magnetic resonance analysis, and therefore accurate analysis is not possible. 1 H NMR data could not be obtained. Molecular weight and distribution: M n =2830, M w =3394, M w / M n =1.20.

[0042] From the above structural identification data, it was confirmed that the synthesized compound is the target adhesive of the present invention, that is, an adhesive that combines the dual functions of moisture absorption prevention and intuitive detection of coating uniformity.

[0043] Adhesive performance analysis test: (1) Mechanical properties of elastomers The adhesive of the present invention, having a number average molecular weight of 2830, was mixed with a curing agent, trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether, and heat cured to an R value of 1.2. The mechanical properties of the produced polyurethane elastomer were a maximum tensile strength of 4.23 MPa and an elongation at break of 355%. (2) Glass transition temperature (T g ) measurement Glass transition temperature (T g) is an important parameter for evaluating the low-temperature mechanical properties of an adhesive, and the Tg of this adhesive measured by DSC was -68.8°C (Figure 1), indicating that the adhesive has good thermal stability. (3) Measurement of fluorescence quantum yield After encapsulating C-coumarin into the MOF808 cage, the spectroscopic properties of the C-coumarin@MOF808 complex were transformed into more useful solid-state fluorescent ones, and its solid-state fluorescence quantum yield increased to 96%, as shown in Table 1 .

[0044] [Table 1] (4) Measurement of adhesive viscosity The viscosity of this adhesive was 6.9 Pa·s at 20°C, which was moderate. When the viscosity was measured at different temperatures, the experimental results showed that the viscosity of all adhesives gradually decreased with increasing temperature, as shown in Table 2. This is because as the temperature increases, the movement of the adhesive's molecular chains becomes faster, the entanglement between the molecular chains decreases, the spacing between them increases, and the internal friction force decreases, resulting in a decrease in viscosity.

[0045] [Table 2]

[0046] Example 2: This example demonstrates the use of an adhesive to combine the dual functions of moisture protection and intuitive detection of coating uniformity for aluminum hydride.

[0047] The adhesive used in this example was the adhesive manufactured in Example 1 above, which has the dual functions of preventing moisture absorption and intuitively detecting coating uniformity.

[0048] The specific process of the coating is as follows. First Step: 5.0 g of trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether was dissolved in 50.0 mL of 1,2-dichloroethane to prepare a trifunctional terminal hydroxyethylene oxide tetrahydrofuran copolymer ether solution. Second step: First, 10.0 mL of adhesive was diluted with 20.0 mL of 1,2-dichloroethane solvent, and then 200.0 g of weighed α-AlH3 was added to the reaction solution. Next, 10.0 mL of the trifunctional hydroxyethylene oxide-tetrahydrofuran copolymer ether solution prepared in the first step was added to the reaction solution. Finally, one drop of dibutyltin dilaurate (DBTDL) was added and the mixture was stirred at room temperature for 3.0 hours. The progress of the coating reaction was monitored in real time using a UV lamp. Third step: After the coating reaction was completed, the mixture was filtered with suction using a funnel, and the resulting solid was washed with 1,2-dichloroethane 3-5 times and dried to obtain the coated product.

[0049] Performance analysis test of coated products: (5) Contact angle test of α-AlH3 before and after coating The contact angle of α-AlH3 after coating with the adhesive of the present invention was measured, and the experimental results are shown in Figure 2. The experimental results show that the contact angle of α-AlH3 before coating was 18°, indicating strong hygroscopicity, and the contact angle after coating was 88°, indicating near hydrophobicity. (6) Moisture absorption test of α-AlH3 before and after coating α-AlH3 and adhesive-coated α-AlH3 composites using the dryer equilibration method FeeMoisture absorption was measured using the weight gain method. The α-AlH3 samples before and after coating were left at room temperature under various humidity conditions, including 75% humidity, for extended periods, and moisture absorption curves were recorded. As shown in Figure 3, the moisture absorption performance of the α-AlH3 samples after coating significantly decreased as humidity increased at 25°C. As shown in Figure 4, the moisture absorption performance of the α-AlH3 samples after coating also significantly decreased when kept at 25°C and 75% humidity. This is presumably due to the tight bond between the adhesive and the α-AlH3, which effectively suppresses the reaction between the α-AlH3 and water vapor. The contact angle of α-AlH3 is 18°, and after coating with adhesive, the contact angle becomes 88°. Due to its hydrophobicity, the adhesive film coated on the surface of α-AlH3 can effectively isolate moisture from the surrounding environment, reducing its hygroscopicity. This characteristic is advantageous for the long-term storage and application of α-AlH3. (7) Electrostatic sensitivity test of α-AlH3 before and after coating According to the static electricity sensitivity measurement method of China National Military Standard GJB-5891.27-2006, the static electricity sensitivity was measured before and after coating with α-AlH3, and the results are shown in Table 3.

[0050] [Table 3] As can be seen from Table 3, the α-AlH3 before coating had a high electrostatic sensitivity of 367 mJ, while the α-AlH3 after coating did not ignite even when the E-50 dropped to the upper test limit of 5390 mJ. These results indicate that the electrostatic sensitivity of α-AlH3 can be reduced by using the adhesive of the present invention. The reason for this is thought to be that the coating formed on the surface of the α-AlH3 by the adhesive exerts a physical blocking effect, reducing stimulation from external static electricity, thereby significantly reducing electrostatic sensitivity. (8) Surface element analysis of α-AlH3 after coating completion The results of the surface elemental analysis after the completion of the α-AlH3 coating are shown in Figure 5 and Table 4.

[0051] [Table 4] (9) The intuitive detection diagram of the uniformity of α-AlH3 after coating is shown in Figure 6, and the scanning electron microscope diagram is shown in Figure 7. (10) Thermal performance analysis The thermal performance of α-AlH3 before and after coating was measured. As shown in Fig. 8, the DSC measurement results showed that the thermal decomposition peak temperature of α-AlH3 after coating was delayed by about 4.1°C compared with that of α-AlH3 before coating, indicating that the thermal stability of α-AlH3 was significantly improved.

[0052] Comparative Example 1: This comparative example provided a manufacturing method for an adhesive that differed from the manufacturing method of Example 1 only in the formulation.

[0053] In the third step of Example 1, the molar ratio of adhesive molecule containing three thermosetting groups (compound 2) to MOF808@7-hydroxy-C-coumarin was 1:1.

[0054] In contrast, in the third step of this comparative example, 5.0 g of the adhesive molecule (compound 2) containing three thermosetting groups and 5.0 g of MOF808@7-hydroxy-C-coumarin were used, with a molar ratio of the two being 1:2. The yield was 88%. When the coating experiment in Example 2 was performed using the adhesive produced in this comparative example, the coating effect was poor and the adhesive coagulated, as shown in Figures 9 and 10.

[0055] Comparative Example 2: This comparative example provided a manufacturing method for an adhesive that differed from the manufacturing method of Example 1 only in the formulation.

[0056] In the third step of Example 1, the molar ratio of adhesive molecule containing three thermosetting groups (compound 2) to MOF808@7-hydroxy-C-coumarin was 1:1.

[0057] In the third step of this comparative example, the adhesive molecule (compound 2) containing three thermosetting groups was 5.0 g, and the MOF808@7-hydroxy-C-coumarin was 5.0 g, with a molar ratio of 1:3. The yield was 90%.

[0058] When the coating experiment in Example 2 was carried out using the adhesive produced in this comparative example, almost no coating effect was observed, as shown in FIGS.

Claims

1. An adhesive characterized by having the following structural formula: 【Chemistry 1】 [Wherein X is an integer of 5 to 20.]

2. The adhesive of claim 1 , wherein X is an integer from 6 to 10.

3. A method for producing the adhesive according to claim 1 or 2, a first step of synthesizing a solid fluorescent probe with high fluorescence quantum yield, the solid fluorescent probe with high fluorescence quantum yield being MOF808@7-hydroxy-C-coumarin, the first step being to weigh out 7-hydroxy-C-coumarin and MOF-808, add them to a reaction flask containing methanol, and allow them to stand for 3 days; after the reaction is complete, remove the filtrate using a funnel, and the resulting solid material is repeatedly washed with methanol; and dry the resulting MOF808@7-hydroxy-C-coumarin at room temperature; a second step of synthesizing an adhesive molecule having three thermosetting groups, in which 1-(6-cyanohexyl)-3-(6-isocyanatohexyl)urea is dissolved in THF at 0°C, and then dilute hydrochloric acid is added to the reaction solution, and the temperature is gradually raised to 80°C and stirred, and after the reaction is completed, the solution is concentrated to obtain an adhesive molecule having three thermosetting groups; The third step of introducing the solid fluorescent probe into the adhesive molecule is to weigh out the adhesive molecule containing three thermosetting groups and dissolve it in 1,2-dichloroethane solvent, then add 1.625 g of MOF808@7-hydroxy-C-coumarin to the reaction solution, add dibutyltin dilaurate dropwise, and stir at room temperature to produce the adhesive; Including, The method for producing the adhesive molecule containing three thermosetting groups and MOF808@7-hydroxy-C-coumarin is characterized in that the molar ratio is 1:

1.

4. A method for producing the adhesive according to claim 3, comprising: a first step of synthesizing a solid fluorescent probe with high fluorescence quantum yield, the solid fluorescent probe with high fluorescence quantum yield being MOF808@7-hydroxy-C-coumarin, comprising: weighing 15.0 g of 7-hydroxy-C-coumarin and 5.0 g of MOF-808, adding them to a reaction flask containing 50 mL of methanol, and allowing the mixture to stand for 3 days; removing the filtrate using a funnel after the reaction is complete; washing the resulting solid material with methanol 8-10 times; and drying the resulting MOF808@7-hydroxy-C-coumarin at room temperature; A second step of synthesizing an adhesive molecule containing three thermosetting groups, which comprises dissolving 25.0 g of 1-(6-cyanohexyl)-3-(6-isocyanatohexyl)urea in 100 mL of THF at 0°C, adding one drop of diluted hydrochloric acid to the reaction solution, gradually raising the temperature to 80°C, and stirring for 3.0 hours. After the reaction is completed, the solution is concentrated to obtain an adhesive molecule containing three thermosetting groups. a third step of introducing the solid fluorescent probe into the adhesive molecule, in which 5.0 g of adhesive molecule containing three thermosetting groups is weighed and dissolved in 50.0 mL of 1,2-dichloroethane solvent, and then 1.625 g of MOF808@7-hydroxy-C-coumarin is added to the reaction solution, and three drops of dibutyltin dilaurate are added dropwise, followed by stirring at room temperature for 6.0 hours to produce an adhesive; A manufacturing method comprising:

5. 3. Use of the adhesive according to claim 1 or 2 for combining the dual functions of moisture prevention and intuitive detection of coating uniformity for aluminum hydride.

6. 6. Use according to claim 5, characterized in that the amount of adhesive added is 0.5% by weight of the amount of aluminum hydride used.

7. 6. The use according to claim 5, characterized in that the adhesive is coated with aluminum hydride by an in-situ polymerization coating method to obtain a coated product.

8. 8. Use according to claim 7, characterized in that the contact angle of the coated product is 88°.

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