High-performance lipoic acid-based biomass adhesive as well as preparation method and application thereof

Abstract

The invention designs a high-performance lipoic acid-based biomass adhesive as well as a preparation method and application thereof, and belongs to the field of bio-based adhesives in high polymer materials. The lipoic acid-based biomass adhesive disclosed by the invention is a light yellow solid and comprises the following raw material components: lipoic acid, a modifying reagent 1 and a modifying reagent 2. The preparation method of the lipoic acid-based biomass adhesive comprises the following steps: dissolving lipoic acid in a proper amount of an organic solvent, adding a modifying reagent 1, uniformly stirring, adding a catalyst 1, and reacting at a certain temperature; and adding a modifying reagent 2 and a catalyst 2 to react to obtain the lipoic acid bio-based adhesive. The lipoic acid-based biomass adhesive disclosed by the invention has the characteristics of environment friendliness, degradability, high bonding strength, convenience in bonding, recyclability, repeated use, complex environment bonding resistance and the like.

Description

Technical Field

[0001] This invention relates to a high-performance thioctic acid-based biomass adhesive, its preparation method, and its application, belonging to the field of bio-based adhesives in polymer materials technology. Background Technology

[0002] Adhesives are substances that bind different materials together through interfacial adhesion and network cohesion, preventing separation. They are widely used in home building materials, food packaging, energy electronics, biomedicine, and aerospace, playing a vital role in modern society. For a long time, petroleum-based adhesives have dominated the market due to their high bonding strength, strong stability, and simple preparation process. However, the extensive use of petroleum-based adhesives exacerbates environmental problems such as petroleum resource depletion and white pollution. Furthermore, some commonly used petroleum-based adhesives release toxic substances such as formaldehyde or toxic organic solvents during use, posing potential risks. Therefore, the development of environmentally friendly, biodegradable, non-toxic, and harmless high-performance bio-based adhesives is of great significance.

[0003] The use of biomass to prepare bio-based adhesives is a cornerstone of the future chemical industry and is crucial to human society. The development of environmentally friendly materials using renewable raw materials has attracted widespread attention, with increasing efforts focused on developing bio-based adhesives from plant oils, proteins, polysaccharides, and other biomass. Bio-based adhesives possess advantages such as wide availability of raw materials, non-toxicity, environmental friendliness, low cost, and fast bonding speed, showing great application potential. However, developing high-performance bio-based adhesives that outperform petroleum-based adhesives remains a challenging task. Currently, bio-based adhesives generally suffer from several shortcomings: ① low bond strength (prone to detachment, unsafe); ② weak adhesion in complex environments (difficult to bond underwater, in solvents, or in oily environments); ③ high bonding and curing requirements (often requiring high temperatures and high energy consumption); ④ insufficient balance between cohesion and adhesion, and strength and toughness (difficult to apply, prone to cracking). Therefore, further research is needed to improve the performance of bio-based adhesives. Furthermore, research on bio-based adhesives can also enable the high-value utilization of some low-value biological raw materials, improving their economic benefits.

[0004] Biomass lipoic acid (LA) is a natural product and dietary supplement used as an antioxidant, and its application in the adhesive field is attracting increasing attention. The disulfide bonds in LA undergo ring-opening polymerization in a molten state to form polylipoic acid. Polylipoic acid is rich in carboxylic acid groups, exhibiting certain adhesive properties, but its crystallization characteristics inhibit the improvement of adhesive effects. Although studies have used vinyl copolymerization and metal ion coordination to suppress crystallization, imparting good adhesion and recyclability, the adhesive strength remains insufficient. Therefore, it is of great significance to improve the high-quality utilization of lipoic acid by designing a reasonable structure that gives it high adhesive strength and high recyclability. Summary of the Invention

[0005] The purpose of this invention is to provide a high-performance thioctic acid-based biomass adhesive. Bio-based adhesives are more environmentally friendly, biodegradable, and non-toxic than petroleum-based adhesives, but they generally have low bond strength, poor water resistance, and poor low-temperature resistance. Naturally occurring biomass thioctic acid contains highly active carboxyl groups and disulfide bonds, exhibiting excellent antioxidant, free radical scavenging, and heavy metal chelating effects. The high-performance thioctic acid-based biomass adhesive provided by this invention exhibits high bond strength in air (the highest bond strength among thioctic acid adhesives) and excellent bonding ability even in complex environments.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A high-performance thioctic acid-based biomass adhesive, wherein the thioctic acid-based biomass adhesive is grafted with a modifying agent 1 through the highly active carboxyl reaction site of thioctic acid to form a thioctic acid esterified product, namely product 1; and then grafted with a modifying agent 2 to form a thioctic acid-based biomass adhesive; wherein the modifying agent 1 is one or a combination of two or more of N-hydroxysuccinimide (NHS), N,N'-disuccinimide carbonate (DSCN), N-hydroxyphthalimide (HOPht), N-hydroxy-5-norbornene-2,3-dicarboximide (HONB), and 1-hydroxybenzotriazole (HOBt); wherein the modifying agent 2 is one or a combination of two or more of 4-aminophenylboronic acid, 3-aminophenylboronic acid, 2-aminophenylboronic acid, (3-amino-5-methylphenyl)boronic acid, and 3-amino-4-fluorophenylboronic acid.

[0008] Furthermore, the high-performance thioctic acid-based biomass adhesive has a high content of bio-based components and an adhesive strength of 6-24 MPa in air; the adhesive strength in other complex environments (such as pure water, 5% NaCl solution, acidic solution with pH=1, and alkaline solution with pH=14) is not less than 18 MPa.

[0009] The preparation method of the above-mentioned high-performance thioctic acid-based biomass adhesive includes the following steps:

[0010] (1) Dissolve lipoic acid in an organic solvent, add modifying agent 1 and stir until uniform, then add catalyst 1. After reaction, purify to obtain product 1.

[0011] (2) Dissolve product 1 in an organic solvent, add modifying agent 2 and stir until homogeneous, then add catalyst 2 and react to obtain a mixed liquid;

[0012] (3) The desired product is separated by stirring, precipitation and chromatography, and then vacuum dried to obtain the final thioctic acid-based biomass adhesive.

[0013] Furthermore, the mass ratio of thioctic acid to modifying agent 1 is 1:(0.05-6), with an optimized ratio of 1:(1-3), and the mass ratio of product 1 to modifying agent 2 is 1:(0.1-2), with an optimized ratio of 1:(0.2-1).

[0014] Further, in step (1), the catalyst 1 is one or more of sodium hydroxide, potassium hydroxide, triethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and pyridine; the mass ratio of lipoic acid to catalyst 1 is 1:(0.05-6), and the optimized ratio is 1:(1-3); the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and acetonitrile.

[0015] Further, in step (2), the catalyst 2 is one or more of sodium hydroxide, potassium hydroxide, triethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and pyridine, and the mass ratio of the modifying agent 2 to the catalyst 2 is 1:(0.01-2.4), with an optimized ratio of 1:(0.02-1.2); the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0016] Furthermore, in step (1), the reaction is mixed by one or more of the following methods: mechanical stirring, magnetic stirring, ultrasonic oscillation, and high-speed shearing; the reaction temperature is 0-30℃ and the reaction time is 1-6 h.

[0017] Furthermore, in step (2), the reaction time is 6-18 h and the reaction temperature is 0-30℃.

[0018] Furthermore, in step (3), the vacuum drying temperature is -30 to 40°C, and the vacuum drying time is 5 to 24 hours.

[0019] The above-mentioned application of a thioctic acid-based biomass adhesive is characterized in that: the thioctic acid-based biomass adhesive is used for bonding various materials in air, or for bonding various materials in other complex environments (such as pure water, 5% NaCl solution, acidic solution with pH=1, alkaline solution with pH=14).

[0020] The beneficial effects of this invention are as follows: This invention utilizes the dynamic disulfide bonds and active carboxyl groups of natural biomass lipoic acid. First, the carboxyl groups are esterified, and then aminophenylboronic acid is grafted onto them. After curing, a dynamic lipoic acid-based biomass adhesive is constructed, exhibiting a polar hydrophobicity, strong and tough balance, high adhesive strength, and suitability for bonding in complex environments. The disulfide bonds and cyclic triboroxane impart dual dynamic properties and water resistance to the adhesive, while the amide and boric acid groups provide excellent interfacial affinity and adhesion.

[0021] (1) This invention synthesizes a unique thioctic acid-based biomass adhesive. The disulfide bond and cyclic triborooxane structure endow it with good dynamics and a tough cohesive network, and it also has good hydrophobicity. The amide group and boric acid group endow it with good interfacial affinity and adhesion.

[0022] (2) The present invention synthesizes a thioctic acid-based biomass adhesive, which, compared with petroleum-based adhesives, is environmentally friendly, biodegradable, non-toxic and harmless, and can be reused.

[0023] (3) The thioctic acid-based biomass adhesive of the present invention has a wide range of applications. It can be used for heat-assisted solventless bonding of various substrates and can also be applied to bonding in complex environments, thus broadening the application conditions and scope.

[0024] (4) The preparation process of this invention is safe and simple to operate, highly repeatable, and easy to achieve large-scale production. Attached Figure Description

[0025] Figure 1 Examples and comparative examples of thioctic acid-based biomass adhesives for bonding strength on stainless steel substrates;

[0026] Figure 2 Bond strength of thioctic acid-based biomass adhesives after one day of treatment under different environments;

[0027] Figure 3 A comparison of the bond strength of thioctic acid-based biomass adhesives and other commercial adhesives to steel. Detailed Implementation

[0028] Unless otherwise specified, all reagents used in the embodiments of this invention can be purchased commercially.

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the following specific embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. If those skilled in the art make some non-essential adjustments and improvements to the present invention based on the above content, they shall still fall within the protection scope of the present invention.

[0030] Example 1:

[0031] The preparation method of lipoic acid-based biomass adhesive 1 is as follows: 5 g of lipoic acid (LA) is dissolved in 100 mL of acetonitrile, then 5 g of N,N'-disuccinimidyl carbonate (DSCN) is added and stirred evenly, then 5 g of triethylamine is added, and the reaction is carried out at room temperature for 2 h. After rotary evaporation concentration, separation and precipitation with 5% NaHCO3 solution and freeze drying, the product LA-NHS1 is obtained. 5 g of product 1 is dissolved in 20 mL of N,N-dimethylformamide (DMF), 1 g of 3-aminophenylboronic acid (ABA) is added and stirred evenly, then 0.1 g of triethylamine is added and reacted. After reacting at room temperature for 12 h, the final lipoic acid-based biomass adhesive, product 1, is obtained by precipitation, chromatography separation and vacuum drying (35℃, 12 h).

[0032] Example 2:

[0033] The preparation method of lipoic acid-based biomass adhesive 2 is as follows: 5 g of lipoic acid (LA) is dissolved in 100 mL of acetonitrile, then 10 g of N,N'-disuccinimidyl carbonate (DSCN) is added and stirred evenly, then 5 g of triethylamine is added, and the reaction is carried out at room temperature for 2 h. After rotary evaporation concentration, separation and precipitation with 5% NaHCO3 solution and freeze drying, the product LA-NHS2 is obtained. 5 g of product 1 is dissolved in 20 mL of N,N-dimethylformamide (DMF), 1 g of 3-aminophenylboronic acid (ABA) is added and stirred evenly, then 0.1 g of triethylamine is added and reacted. After reacting at room temperature for 12 h, the final lipoic acid-based biomass adhesive, product 2, is obtained by precipitation, chromatography separation and vacuum drying (35℃, 12 h).

[0034] Example 3:

[0035] The preparation method of lipoic acid-based biomass adhesive 3 is as follows: 5 g of lipoic acid (LA) is dissolved in 100 mL of acetonitrile, then 15 g of N,N'-disuccinimidyl carbonate (DSCN) is added and stirred evenly, then 5 g of triethylamine is added, and the reaction is carried out at room temperature for 2 h. After rotary evaporation concentration, separation and precipitation with 5% NaHCO3 solution and freeze drying, the product LA-NHS3 is obtained. 5 g of product 1 is dissolved in 20 mL of N,N-dimethylformamide (DMF), 1 g of 3-aminophenylboronic acid (ABA) is added and stirred evenly, then 0.1 g of triethylamine is added and reacted. After reacting at room temperature for 12 h, the final lipoic acid-based biomass adhesive, product 3, is obtained by precipitation, chromatography separation and vacuum drying (35℃, 12 h).

[0036] Example 4:

[0037] The preparation method of lipoic acid-based biomass adhesive 4 is as follows: 5 g of lipoic acid (LA) is dissolved in 100 mL of acetonitrile, then 10 g of N,N'-disuccinimidyl carbonate (DSCN) is added and stirred evenly, then 10 g of triethylamine is added, and the reaction is carried out at room temperature for 2 h. After rotary evaporation concentration, separation and precipitation with 5% NaHCO3 solution and freeze drying, the product LA-NHS4 is obtained. 5 g of product 1 is dissolved in 20 mL of N,N-dimethylformamide (DMF), 1 g of 3-aminophenylboronic acid (ABA) is added and stirred evenly, then 0.1 g of triethylamine is added and reacted. After reacting at room temperature for 12 h, the final lipoic acid-based biomass adhesive, product 4, is obtained by precipitation, chromatography separation, and vacuum drying (35℃, 12 h).

[0038] Example 5:

[0039] The preparation method of lipoic acid-based biomass adhesive 5 is as follows: 5 g of lipoic acid (LA) is dissolved in 100 mL of acetonitrile, then 10 g of N,N'-disuccinimidyl carbonate (DSCN) is added and stirred evenly, then 15 g of triethylamine is added, and the reaction is carried out at room temperature for 2 h. After rotary evaporation concentration, separation and precipitation with 5% NaHCO3 solution and freeze drying, the product LA-NHS5 is obtained. 5 g of product 1 is dissolved in 20 mL of N,N-dimethylformamide (DMF), 1 g of 3-aminophenylboronic acid (ABA) is added and stirred evenly, then 0.1 g of triethylamine is added and reacted. After reacting at room temperature for 12 h, the final lipoic acid-based biomass adhesive, product 5, is obtained by precipitation, chromatography separation, and vacuum drying (35℃, 12 h).

[0040] Example 6:

[0041] The preparation method of lipoic acid-based biomass adhesive 6 is as follows: 5 g of lipoic acid (LA) is dissolved in 100 mL of acetonitrile, then 10 g of N,N'-disuccinimidyl carbonate (DSCN) is added and stirred evenly, then 10 g of triethylamine is added, and the reaction is carried out at room temperature for 2 h. After rotary evaporation concentration, separation and precipitation with 5% NaHCO3 solution and freeze drying, the product LA-NHS6 is obtained. 5 g of product 1 is dissolved in 20 mL of N,N-dimethylformamide (DMF), 3 g of 3-aminophenylboronic acid (ABA) is added and stirred evenly, then 0.1 g of triethylamine is added and reacted. After reacting at room temperature for 12 h, the final lipoic acid-based biomass adhesive, product 6, is obtained by precipitation, chromatography separation and vacuum drying (35℃, 12 h).

[0042] Example 7:

[0043] The preparation method of lipoic acid-based biomass adhesive 7 is as follows: 5 g of lipoic acid (LA) is dissolved in 100 mL of acetonitrile, then 10 g of N,N'-disuccinimidyl carbonate (DSCN) is added and stirred evenly, then 10 g of triethylamine is added, and the reaction is carried out at room temperature for 2 h. After rotary evaporation concentration, separation and precipitation with 5% NaHCO3 solution and freeze drying, the product LA-NHS7 is obtained. 5 g of product 1 is dissolved in 20 mL of N,N-dimethylformamide (DMF), 5 g of 3-aminophenylboronic acid (ABA) is added and stirred evenly, then 0.1 g of triethylamine is added and reacted. After reacting at room temperature for 12 h, the final lipoic acid-based biomass adhesive, product 7, is obtained by precipitation, chromatography separation, and vacuum drying (35℃, 12 h).

[0044] Example 8:

[0045] The preparation method of lipoic acid-based biomass adhesive 8 is as follows: 5 g of lipoic acid (LA) is dissolved in 100 mL of acetonitrile, then 10 g of N,N'-disuccinimidyl carbonate (DSCN) is added and stirred evenly, then 10 g of triethylamine is added, and the reaction is carried out at room temperature for 2 h. After rotary evaporation concentration, separation and precipitation with 5% NaHCO3 solution and freeze drying, the product LA-NHS8 is obtained. 5 g of product 1 is dissolved in 20 mL of N,N-dimethylformamide (DMF), 3 g of 3-aminophenylboronic acid (ABA) is added and stirred evenly, then 1.95 g of triethylamine is added and reacted. After reacting at room temperature for 12 h, the final lipoic acid-based biomass adhesive, product 8, is obtained by precipitation, chromatography separation, and vacuum drying (35℃, 12 h).

[0046] Example 9:

[0047] The preparation method of lipoic acid-based biomass adhesive 9 is as follows: 5 g of lipoic acid (LA) is dissolved in 100 mL of acetonitrile, then 10 g of N,N'-disuccinimidyl carbonate (DSCN) is added and stirred evenly, then 10 g of triethylamine is added, and the reaction is carried out at room temperature for 2 h. After rotary evaporation concentration, separation and precipitation with 5% NaHCO3 solution and freeze drying, the product LA-NHS9 is obtained. 5 g of product 1 is dissolved in 20 mL of N,N-dimethylformamide (DMF), 3 g of 3-aminophenylboronic acid (ABA) is added and stirred evenly, then 3.6 g of triethylamine is added and reacted. After reacting at room temperature for 12 h, the final lipoic acid-based biomass adhesive, product 9, is obtained by precipitation, chromatography separation and vacuum drying (35℃, 12 h).

[0048] Example 10:

[0049] The preparation method of lipoic acid-based biomass adhesive 10 is as follows: 5 g of lipoic acid (LA) is dissolved in 100 mL of acetonitrile, then 10 g of N-hydroxysuccinimide (NHS) is added and stirred evenly, then 10 g of triethylamine is added, and the reaction is carried out at room temperature for 2 h. After rotary evaporation concentration, separation and precipitation with 5% NaHCO3 solution and freeze drying, the product LA-NHS10 is obtained. 5 g of product 1 is dissolved in 20 mL of N,N-dimethylformamide (DMF), 3 g of 3-aminophenylboronic acid (ABA) is added and stirred evenly, then 1.95 g of triethylamine is added and reacted. After reacting at room temperature for 12 h, the final lipoic acid-based biomass adhesive, product 10, is obtained by precipitation, chromatography separation and vacuum drying (35℃, 12 h).

[0050] Example 11:

[0051] The preparation method of lipoic acid-based biomass adhesive 11 is as follows: 5 g of lipoic acid (LA) is dissolved in 100 mL of acetonitrile, then 10 g of N,N'-disuccinimidyl carbonate (DSCN) is added and stirred evenly, then 10 g of triethylamine is added, and the reaction is carried out at room temperature for 2 h. After rotary evaporation concentration, separation and precipitation with 5% NaHCO3 solution and freeze drying, the product LA-NHS11 is obtained. 5 g of product 1 is dissolved in 20 mL of N,N-dimethylformamide (DMF), 3 g of 4-aminophenylboronic acid (4-ABA) is added and stirred evenly, then 1.95 g of triethylamine is added and reacted. After reacting at room temperature for 12 h, the final lipoic acid-based biomass adhesive, product 11, is obtained by precipitation, chromatography separation and vacuum drying (35℃, 12 h).

[0052] Comparative Example 1

[0053] 5 g of lipoic acid (LA) was dissolved in 100 mL of acetonitrile, then 10 g of N,N'-disuccinimidyl carbonate (DSCN) was added and stirred until homogeneous. 10 g of triethylamine was then added, and the mixture was reacted at room temperature for 2 h. After rotary evaporation, concentration, separation and precipitation with 5% NaHCO3 solution, and lyophilization, the product LA-NHS8 was obtained. 5 g of product 1 was dissolved in 100 mL of acetonitrile, and 12.5 mL of 80% hydrazine solution was added and stirred until homogeneous. The mixture was reacted at room temperature for 3 h, filtered, concentrated under reduced pressure, diluted with 200 mL of dichloromethane, washed three times with 5% NaHCO3 aqueous solution, and then concentrated and vacuum dried (35℃, 12 h) to obtain the final lipoic acid hydrazine (LAH).

[0054] Comparative Example 2

[0055] 5 g of lipoic acid (LA) and 3 g of 3-aminophenylboronic acid (ABA) were dissolved in 10 mL of N,N-dimethylformamide (DMF). The mixture was spread evenly in a polytetrafluoroethylene mold and placed in an oven at 80°C to obtain the composite film LABA.

[0056] Comparative Example 3

[0057] 5 g of lipoic acid (LA) and 3 g of phenylboronic acid (PBA) were dissolved in 10 mL of N,N-dimethylformamide (DMF). The mixture was spread evenly in a polytetrafluoroethylene mold and placed in an oven at 80°C to obtain the composite film LAPBA.

[0058] The performance of the thioctic acid-based biomass adhesives prepared in Examples 1-7 and Comparative Examples 1-3 was tested using the following methods:

[0059] (1) Bond strength test for stainless steel substrate

[0060] Stainless steel substrate shear sheets of thioctic acid-based biomass adhesives were prepared at room temperature and measured using a dual-column benchtop testing system.

[0061] (2) Bond strength test under complex environment

[0062] Stainless steel shearing discs for preparing thioctic acid-based biomass adhesives were immersed for one day in pure water, 5% NaCl solution, acidic solution with pH=1, and alkaline solution with pH=14 at room temperature, and then measured using a dual-column benchtop test system.

[0063] Figure 1In Examples 1-3, N,N'-disuccinimidyl carbonate (DSCN) was used for esterification to activate the carboxyl groups of lipoic acid, followed by amidation of grafted phenylboronic acid. During curing, the boric acid groups could condense into cyclic borate esters, compensating for insufficient cohesion and resulting in high adhesive strength. With increasing DSCN content, the carboxyl groups of lipoic acid were more fully activated, increasing adhesive strength. Further increases in DSCN content resulted in little change or a slight decrease in adhesive strength. In Examples 2, 4, and 5, increasing the amount of catalyst 1 facilitated the reaction; further increases led to side reactions. In Examples 4, 6, and 7, increasing the amount of 3-aminophenylboronic acid resulted in more complete amidation of the LA-NHS intermediate, increasing adhesive strength. However, further increases in 3-aminophenylboronic acid content increased the likelihood of side reactions, making purification more difficult and ultimately decreasing the adhesive strength of the lipoic acid-based adhesive. In Examples 6, 8, and 9, increasing the amount of catalyst 2 helps increase the reaction efficiency, but further increases lead to side reactions and reduce the adhesive strength of the products. N-hydroxysuccinimide (NHS) in Example 10 and 4-aminophenylboronic acid in Example 11 have similar structures and properties to DSCN and 3-aminophenylboronic acid in Example 8, so the adhesive strength of the products is not significantly different. In Example 8, lipoic acid is grafted with 3-aminophenylboronic acid, while in Comparative Example 1, lipoic acid is grafted with hydrazine. The adhesive strength of lipoic acid is greater than that of lipoic acid hydrazine. This is attributed to the fact that during the curing of lipoic acid hydrazine, besides the ring-opening connection of disulfide bonds, only the hydrogen bonding between the amide and amino groups is involved, resulting in insufficient cohesion and lower adhesive strength. In contrast, during the curing of lipoic acid hydrazine, in addition to the ring-opening connection of disulfide bonds, the hydrogen bonding between the amide and boric acid, and the condensation of boric acid into cyclic borate ester crosslinking, the cohesion of the adhesive is increased, thereby increasing the adhesive strength. The comparison between Examples 1-9 and Comparative Examples 2 and 3 shows that grafting contributes much more to the bond strength than simple blending.

[0064] It is precisely because of the combination of the above-mentioned advantages that thioctic acid-based biomass adhesives are able to... Figure 2 It exhibits excellent adhesive properties in various complex environments. Figure 3 The bonding strength of the thioctic acid-based biomass adhesive to steel was compared with that of other commercial adhesives. The results showed that the thioctic acid-based biomass adhesive prepared in this invention has excellent performance and is also the thioctic acid-based adhesive with the highest reported bonding strength to date.

Claims

1. A high-performance thioctic acid-based biomass adhesive, characterized in that: The lipoic acid-based biomass adhesive is grafted with modifying agent 1 through the highly active carboxyl reaction site of lipoic acid to form a lipoic acid esterified product, namely product 1; then modified agent 2 is grafted to form the lipoic acid-based biomass adhesive. The modifying agent 1 is one or more of N-hydroxysuccinimide, N,N'-disuccinimide carbonate, N-hydroxyphthalimide, N-hydroxy-5-norbornene-2,3-dicarboximide, and 1-hydroxybenzotriazole. The modifying reagent 2 is one or a combination of two or more of 4-aminophenylboronic acid, 3-aminophenylboronic acid, 2-aminophenylboronic acid, (3-amino-5-methylphenyl)boronic acid, and 3-amino-4-fluorophenylboronic acid.

2. The high-performance thioctic acid-based biomass adhesive as described in claim 1, characterized in that: Thioctanoic acid-based biomass adhesives have a high content of bio-based components and an adhesive strength of 6-24 MPa in air; the adhesive strength in other complex environments is not less than 18 MPa.

3. A method for preparing a high-performance thioctic acid-based biomass adhesive according to any one of claims 1-2, characterized in that, Includes the following steps: (1) Dissolve lipoic acid in an organic solvent, add modifying agent 1 and stir until uniform, then add catalyst 1. After reaction, purify to obtain product 1. (2) Dissolve product 1 in an organic solvent, add modifying agent 2 and stir until homogeneous, then add catalyst 2. After reaction, a mixed liquid is obtained. (3) The desired product is separated by stirring, precipitation and chromatography, and then vacuum dried to obtain the final thioctic acid-based biomass adhesive.

4. The preparation method of the high-performance thioctic acid-based biomass adhesive as described in claim 3, characterized in that: In step (1), the mass ratio of lipoic acid to modifying reagent 1 is 1:(0.5-6); the catalyst 1 is one or more of sodium hydroxide, potassium hydroxide, triethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, and pyridine; the mass ratio of lipoic acid to catalyst 1 is 1:(0.5-6); the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and acetonitrile.

5. The method for preparing the high-performance thioctic acid-based biomass adhesive according to claim 3, characterized in that: In step (2), the mass ratio of product 1 to modifying agent 2 is 1:(0.1-2); the catalyst 2 is one or more of sodium hydroxide, potassium hydroxide, triethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, and pyridine, and the mass ratio of modifying agent 2 to catalyst 2 is 1:(0.01-2.4); the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

6. The method for preparing high-performance thioctic acid-based biomass adhesive according to claim 3, in step (1), the mass ratio of thioctic acid to modifying agent 1 is 1:(1-3); the mass ratio of thioctic acid to catalyst 1 is 1:(1-3); in step (2), the mass ratio of product 1 to modifying agent 2 is 1:(0.2-1); the mass ratio of modifying agent 2 to catalyst 2 is 1:(0.02-1.2).

7. The method for preparing the high-performance thioctic acid-based biomass adhesive according to claim 4, characterized in that: In step (1), the reaction is mixed by one or more of the following methods: mechanical stirring, magnetic stirring, ultrasonic oscillation, and high-speed shearing; the reaction temperature is 0-30℃ and the reaction time is 1-6 h.

8. The method for preparing the high-performance thioctic acid-based biomass adhesive according to claim 4, characterized in that: In step (2), the reaction time is 6-18 h and the reaction temperature is 0-30℃.

9. The method for preparing the high-performance thioctic acid-based biomass adhesive according to claim 4, characterized in that: In step (3), the vacuum drying temperature is -30 to 40°C and the vacuum drying time is 5 to 24 hours.

10. The application of a high-performance thioctic acid-based biomass adhesive according to any one of claims 1-3, or a thioctic acid-based biomass adhesive prepared by any one of claims 4-9, characterized in that, The thioctic acid-based biomass adhesive is used for bonding various materials in air, or for bonding various materials in other complex environments.

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