阅读说明：本技术 一种纳米胶粘剂及其制备方法和应用 (Nano adhesive and preparation method and application thereof ) 是由 张静 吴志连 张侃 俞波 王耀国 于 2021-09-22 设计创作，主要内容包括：本申请公开了一种纳米胶粘剂的制备方法和应用。所述纳米胶粘剂包括具有类儿茶酚结构的化合物、丝素蛋白和硅烷偶联剂改性的纳米材料；所述制备方法包括将丝素蛋白水溶液、聚乙二醇水溶液与水混合,得到混合溶液,再加入具有类儿茶酚结构的化合物和硅烷偶联剂改性的纳米材料。所述纳米胶粘剂能够在汽车、医疗、木材加工等领域应用,在干湿状态下对铝片、猪皮、木材的拉伸剪切强度>2MPa。合成工艺未涉及任何有毒、有气味原料、属于真正的绿色环保产品。(The application discloses a preparation method and application of a nano adhesive. The nano adhesive comprises a compound with a catechol-like structure, silk fibroin and a silane coupling agent modified nano material; the preparation method comprises the steps of mixing silk fibroin aqueous solution, polyethylene glycol aqueous solution and water to obtain mixed solution, and then adding a compound with a catechol structure and a silane coupling agent modified nano material. The nano adhesive can be applied to the fields of automobiles, medical treatment, wood processing and the like, and has tensile shear strength of more than 2MPa to aluminum sheets, pigskins and wood in a dry and wet state. The synthesis process does not involve any toxic and odorous raw materials, and belongs to a real green and environment-friendly product.)

1. A nanocomposite comprising at least one of a compound having a structure of formula (la), silk fibroin, and a crosslinking agent;

wherein R is₁Selected from H, -OH, -OCH₃One of (1); r₂Selected from H, -COOH, -CH₃、-CH₂CH₂NH₂One of (1); r₃One selected from H and-OH;

wherein the mass ratio of the compound with the structure as shown in the formula I, the silk fibroin and the cross-linking agent is 25-40%: 20% -45%: 2 to 15 percent.

2. The nanocomposite as claimed in claim 1, wherein the compound having the structure of formula (la) is selected from at least one of dopamine, tannic acid, gallic acid, catechol, guaiacol, 2-methoxy-4-methylphenol;

the cross-linking agent is selected from at least one of nano montmorillonite, nano silicon dioxide and nano titanium dioxide.

3. Nanocomposite material according to claim 1,

the cross-linking agent is modified by a silane coupling agent;

the silane coupling agent is selected from at least one of KH560, KH540 and KH 550;

the modification method comprises the steps of mixing an aqueous solution containing the cross-linking agent with a silane coupling agent, and heating for reaction.

4. A method for preparing a nanocomposite material according to any one of claims 1 to 3, comprising the steps of:

and mixing the silk fibroin aqueous solution and the polyethylene glycol aqueous solution to obtain a mixed solution, adding the compound with the structure shown as the formula I and the cross-linking agent, and stirring to obtain the nano material.

5. The preparation method of claim 4, wherein the silk fibroin is subjected to a pretreatment process;

the pretreatment process comprises the following steps: breaking or peeling silkworm cocoon into a plurality of layers, boiling and adding anhydrous sodium carbonate for degumming, washing and drying by deionized water, dissolving in LiBr solution, filtering, repeatedly dialyzing until the conductivity is not changed, and then performing reverse dialysis in polyethylene glycol solution to obtain the silk fibroin;

the boiling time is 20-40 min;

the amount of the anhydrous sodium carbonate is 20-30 g.

6. The production method according to claim 4,

the mass fraction of silk fibroin in the silk fibroin aqueous solution is 8-10%;

the mass fraction of polyethylene glycol in the polyethylene glycol aqueous solution is 40-60%;

the mass ratio of the mass of the polyethylene glycol to the mass of the silk fibroin aqueous solution is 0.05-0.15;

the mass ratio of the cross-linking agent to the silk fibroin aqueous solution is 0.005-0.0625; the particle size of the cross-linking agent is 50-150 nm.

7. The production method according to claim 4,

the mass ratio of the compound with the structure shown in the formula I to the silk fibroin aqueous solution is 0.05-0.2.

8. The production method according to claim 4,

when the compound with the structure of the formula I is dopamine, tannic acid and gallic acid, the mixed solution also contains a catalyst;

the catalyst is selected from N-hydroxysuccinimide and 1-ethyl- (3-dimethylaminopropyl) carbodiimide; the mass ratio of the catalyst to the fibroin aqueous solution is 0.01-0.012.

9. The preparation method according to claim 4, wherein the stirring time is 3 to 6 hours.

10. Use of the nanocomposite according to claims 1 to 3 or the nanocomposite prepared by the preparation method according to claims 4 to 9 as an adhesive, in the fields of automobiles, medical treatment, and wood processing;

the tensile shear strength of the nano adhesive is greater than 2 MPa.

Technical Field

The application relates to a nano adhesive and a preparation method and application thereof, belonging to the field of nano adhesive preparation.

Background

Some marine organisms such as oysters, barnacles and mussels can still firmly adhere to the moist reefs under the impact of sea waves. In particular mussels, whose feet secrete a viscous liquid protein ┄ mussel adhesive protein. Because the content of the natural mussel adhesive protein is extremely low, the difficulty and the cost for directly extracting the adhesive protein from mussel byssus are high, and the catechol structure in the adhesive protein is the key for adhesion and crosslinking.

Therefore, groups with the functions of mussel adhesive protein, such as dopa and dopamine with a catechol structure, are effectively introduced into silk fibroin with a macromolecular skeleton, and are simultaneously crosslinked with a nano material to prepare a material with water-resistant adhesion similar to that of the mussel adhesive protein, so that a bionic bio-based adhesive is developed. The adhesive has the advantages of good biocompatibility, high bonding strength, strong moisture-proof adhesion capability, quickness, convenience and the like, and is expected to be applied to the fields of automobiles, home furnishing, medical treatment and the like.

At present, starch, soybean protein powder, soybean protein isolate powder, lignin, silk fibroin and the like are generally adopted to carry out hydrophobic modification to a certain degree, the water resistance of the adhesive is improved, and a cross-linking agent is adopted to form a net structure, so that the bio-based adhesive is obtained. But the modification process still involves various materials with high toxicity and strong odor, such as epichlorohydrin, ethylene glycol diglycidyl ether and the like, and is not an environment-friendly adhesive in the true sense.

However, with the enhancement of the environmental awareness of people and the improvement of the national requirement on the green environmental protection of adhesives, and the progress of scientific technology, the chemical adhesives gradually begin to be disintegrated from the biological adhesives of toxic, harmful and polluted to the non-toxic, harmless, green and environmental protection. Most of bio-based adhesives are hydrophilic compounds, and the water resistance of the adhesives is poor. Biomass resources such as soybean protein, starch, lignin, tannic acid and the like are used for replacing petrochemical raw materials, and the improvement technology of the bio-based adhesive in the aspects of bonding strength, water resistance and the like is researched, so that the bio-based adhesive has important application value and practical significance.

Disclosure of Invention

In view of the defects of the prior art, the invention takes a bio-based raw material silk fibroin as a macromolecular skeleton, exposes more hydrophilic polar groups by self-assembly under the action of PEG, performs chemical bond or hydrogen bond reaction with dopamine, tannic acid, gallic acid, catechol and the like with catechol similar structures, and then performs crosslinking reaction with a nano material modified by a silane coupling agent again to increase the water resistance of the nano material, thereby finally obtaining the non-toxic environment-friendly bio-based adhesive with high tensile shear strength, strong moisture resistance, short curing time and good viscosity on aluminum sheets, wood and pigskin.

According to one aspect of the present application, there is provided a nanocomposite comprising at least one of compounds having a structure of formula (la), silk fibroin, and a crosslinking agent;

wherein R is₁Selected from H, -OH, -OCH₃One of (1); r₂Selected from H, -COOH, -CH₃、-CH₂CH₂NH₂One of (1); r₃One selected from H, -OH and the like;

wherein the mass ratio of the compound with the structure as shown in the formula I, the silk fibroin and the cross-linking agent is 25-40%: 20% -45%: 2 to 15 percent.

The compound with the structure of the formula I is a compound with a catechol-like structure.

The compound with the structure shown in the formula I is selected from at least one of dopamine, tannic acid, gallic acid, catechol o-methoxyphenol and 2-methoxy-4-methylphenol;

the cross-linking agent is selected from at least one of nano montmorillonite, nano silicon dioxide and nano titanium dioxide;

the cross-linking agent is modified by a silane coupling agent;

the silane coupling agent is selected from at least one of KH560, KH540 and KH 550;

the modification method comprises the steps of mixing an aqueous solution containing the cross-linking agent with a silane coupling agent, and heating for reaction;

preparing the cross-linking agent into a 1% aqueous solution, adding a silane coupling agent, reacting at 50 ℃ for 6 hours, and then centrifugally drying;

the mass ratio of the silane coupling agent to the nano material is 1: 2-3: 1; the upper limit of the mass ratio of the silane coupling agent to the nanomaterial is selected from one of 3:1, 3:2 and 2: 1; the lower limit of the mass ratio of the silane coupling agent to the nanomaterial is selected from one of 1:2, 1:1, and 2: 3.

According to another aspect of the present application, there is provided a method for preparing a nanomaterial, comprising the steps of:

and mixing the silk fibroin aqueous solution and the polyethylene glycol aqueous solution to obtain a mixed solution, adding the compound with the structure shown as the formula I and the cross-linking agent, and stirring to obtain the nano material.

The mass fraction of silk fibroin in the silk fibroin aqueous solution is 8-10%;

the mass fraction of polyethylene glycol in the polyethylene glycol aqueous solution is 40-60%;

the mass ratio of the mass of the polyethylene glycol to the mass of the silk fibroin aqueous solution is 0.05-0.15; the upper limit of the mass ratio of the polyethylene glycol to the silk fibroin aqueous solution is selected from one of 0.15, 0.125 and 0.1; the lower limit of the mass ratio of the polyethylene glycol to the silk fibroin aqueous solution is selected from one of 0.05, 0.075 and 0.09.

The mass ratio of the cross-linking agent to the silk fibroin aqueous solution is 0.005-0.0625; the upper limit of the mass ratio of the cross-linking agent to the silk fibroin aqueous solution is selected from one of 0.0625, 0.06, 0.05 and 0.04; the lower limit of the mass ratio of the cross-linking agent to the silk fibroin aqueous solution is selected from one of 0.005, 0.01, 0.015 and 0.02. The particle size of the cross-linking agent is 50-150 nm.

The mass ratio of the compound with the structure of the formula I to the silk fibroin aqueous solution is 0.05-0.2; the upper limit of the mass ratio of the compound with the structure of the formula (I) to the silk fibroin aqueous solution is selected from one of 0.2, 0.175 and 0.15; the lower limit of the mass ratio of the compound with the structure of the formula (I) to the silk fibroin aqueous solution is selected from one of 0.05, 0.075 and 0.01.

When the compound with the structure of the formula I is dopamine, the mixed solution also contains a catalyst;

the catalyst is selected from N-hydroxysuccinimide and 1-ethyl- (3-dimethylaminopropyl) carbodiimide; the mass ratio of the catalyst to the fibroin aqueous solution is 0.01-0.012.

The stirring time is 3-6 h.

The preparation method also comprises a pretreatment process of the silk fibroin, and comprises the following steps:

breaking or peeling silkworm cocoon into a plurality of layers, boiling and adding anhydrous sodium carbonate for degumming, washing and drying by deionized water, dissolving in LiBr solution, filtering, repeatedly dialyzing until the conductivity is not changed, and then performing reverse dialysis in polyethylene glycol solution to obtain the silk fibroin;

the method specifically comprises the following steps:

the step (1) is to break or peel purchased silkworm cocoons into a plurality of layers for standby.

And (2) boiling 2L of deionized water in a water bath kettle, adding anhydrous sodium carbonate, weighing the silkworm cocoons treated in the step (1), and putting the silkworm cocoons into the water bath kettle for boiling and degumming.

And (3) drying: and (3) repeatedly washing the silk fibroin obtained after degumming in the step (2) with deionized water for 3 times, standing overnight in an oven to obtain the degummed silk fibroin, and pulling loose for later use.

Step (4) weighing the dried silk fibroin obtained in step (3) at 9.3 mol.L^-1Dissolved in the LiBr solution of (a).

And (5) carrying out suction filtration on the dissolved silk fibroin LiBr solution to remove impurities.

And (6) transferring the silk fibroin solution LiBr subjected to suction filtration into a dialysis bag, and repeatedly dialyzing with deionized water until the conductivity is unchanged.

And (7) performing reverse dialysis on the dialyzed silk fibroin aqueous solution in a polyethylene glycol (M ═ 20000) solution to obtain a silk fibroin aqueous solution with a certain concentration for later use.

Wherein, the content of the anhydrous sodium carbonate in the step (2) is 20-30 g, and the boiling time is 20-40 min.

In the step (3), the temperature of the deionized water is 40-60 ℃, the temperature of the oven is 30-40 ℃, and the time is 24-40 hours.

In the step (4), the mass of the degummed fibroin is 10-20 g, the LiBr solution is 50-100 mL, the dissolving temperature is 30-40 ℃, and the dissolving time is 6-8 h.

In the step (6), the molecular weight of the dialysis bag is 5000-14000, the amount of deionized water used each time is 2-5L, water is changed once in 3h in the day, water is changed once in 12h at night, and dialysis is carried out for 2-4 d.

In the step (7), the dosage of the polyethylene glycol is 1-3L, and the dialysis time is 1.5-4 d.

According to another aspect of the present application, there is provided the use of the nanocomposite described above or the nanomaterial prepared by the preparation method described above as an adhesive in the fields of automotive, medical, wood processing; tensile shear strength >2 MPa.

The invention self-assembles silk fibroin aqueous solution under the action of polyethylene glycol to expose more modifiable groups, introduces dopamine, gallic acid and the like with a catechol structure into a silk fibroin macromolecular skeleton by adopting a polymer bionic method, and simultaneously adds a nano material as a cross-linking agent to carry out secondary cross-linking to obtain the environment-friendly bio-based nano adhesive with high tensile shear strength and strong moisture resistance, which is expected to be applied to the fields of medical treatment, automobiles, wood and the like.

(1) Under the action of polyethylene glycol, self-assembling silk fibroin aqueous solution to expose more modifiable groups, and introducing dopamine (tannic acid and gallic acid) with a catechol-like structure into a silk fibroin macromolecular skeleton by adopting a polymer bionic method;

(2) the nano material is added to be used as a cross-linking agent for secondary cross-linking, so that the environment-friendly bio-based nano adhesive with high tensile shear strength and strong moisture resistance is obtained, and is expected to be applied to the fields of medical treatment, automobiles, wood and the like;

(3) the synthesis process of the adhesive does not relate to any toxic and odorous raw material, and belongs to a real green and environment-friendly product.

Drawings

Fig. 1 is a microphotograph of the nano adhesive prepared in example 2.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

Unless otherwise specified, the raw materials in the examples of the present application were purchased commercially, wherein cocoon was purchased from Ministry of permanent silk products, Ministry of Shanghai, Ministry of training and City, and anhydrous sodium carbonate, lithium bromide, a catechol-like structure material, and a silane coupling agent were purchased from Shanghai Micheln Biochemical technology Co., Ltd or Shanghai Aladdin Biotechnology Co., Ltd. The crosslinking agent was purchased from Tuoyi New materials (Guangzhou) Co.

The method for modifying the cross-linking agent comprises the steps of preparing the adopted cross-linking agent into 1% aqueous solution, adding the adopted silane coupling agent, reacting at 50 ℃ for 6 hours, and then centrifugally drying.

Example 1

Obtaining the silk fibroin aqueous solution.

Crushing or peeling purchased silkworm cocoon into multiple layers, boiling 2L of deionized water in a water bath for 30min, adding 20g of anhydrous sodium carbonate, and boiling the treated silkworm cocoon in the water bath for degumming. Repeatedly washing degummed silk fibroin with 60 deg.C deionized water for 3 times, standing overnight in oven to obtain degummed silk fibroin, loosening, oven drying at 40 deg.C for 24 hr, and dissolving in 9.3 mol. L^-1And (3) carrying out suction filtration on the LiBr solution, transferring the LiBr solution into a dialysis bag with the molecular weight of 5000-14000, repeatedly dialyzing with deionized water, wherein the using amount of the deionized water is 5L each time, water is changed once in 3h in the day, and water is changed once in 12h at night for 2d until the conductivity is not changed. And performing reverse dialysis for 2d in 1L of 40% polyethylene glycol solution with molecular weight of 20000 to obtain silk fibroin aqueous solution with certain concentration.

Example 2

The silk fibroin aqueous solution obtained in example 1 was diluted to 8% by mass, 20g of the solution was taken, and 1g of a 50% by mass polyethylene glycol solution (Mw 20000) was added thereto and magnetically stirred for 30min to promote self-assembly of silk fibroin. 0.1g each of N-hydroxysuccinimide and 1-ethyl- (3-dimethylaminopropyl) carbodiimide was added thereto, and the mixture was stirred for 30 minutes. 1g of dopamine is added and stirred magnetically for 1 hour. Adding 0.1g of silane coupling agent KH560 modified nano montmorillonite, and magnetically stirring for 3h to obtain the nano adhesive.

Fig. 1 is a microphotograph of the nano adhesive prepared in example 2. As can be seen from the figure, the obtained nano adhesive has a network structure which is intertwined with each other.

Example 3

The silk fibroin aqueous solution obtained in example 1 was diluted to a mass fraction of 9%, 20g of the solution was added to a 60% polyethylene glycol solution (Mw 20000)2g of the solution and magnetically stirred for 45min to promote self-assembly of silk fibroin. Then 2.1g of catechol are added and stirred for 2 hours. And adding 0.5g of silane coupling agent KH550 modified nano-silica, and magnetically stirring for 4 hours to obtain the nano-adhesive.

Example 4

The silk fibroin aqueous solution obtained in example 1 was diluted to a mass fraction of 9%, 20g of the solution was added to a 40% polyethylene glycol solution (Mw 20000) of 3g and magnetically stirred for 60min to promote self-assembly of silk fibroin. 0.108g each of N-hydroxysuccinimide and 1-ethyl- (3-dimethylaminopropyl) carbodiimide was added thereto, and the mixture was stirred for 30 minutes. Then 3.2g of gallic acid is added and stirred for 3 hours by magnetic force. Adding 1g of silane coupling agent KH540 modified nano titanium dioxide, and magnetically stirring for 6h to obtain the nano adhesive.

Test example 1

The nano adhesive prepared in example 2 was applied to aluminum sheets, pigskins, and wood for tensile shear strength in dry and wet states, respectively.

And (3) dry state testing: adding a newly prepared adhesive to one end of the base material, standing for 1h, air-drying the surface, immediately covering the other base material on the previous base material to enable the overlapping area to be 25mmx12.5mm, applying slight pressure for about 5-10 s by fingers to enhance the adhesion, curing for 2h at room temperature to obtain a cured sample, and testing the tensile shear strength by using a US INSTRON (5943) universal material testing machine. The tensile shear strengths were 2.9MPa, 2.6MPa, and 3.5MPa, respectively, for the readings on the aluminum sheet, pigskin, and wood substrates divided by the area of the overlap region.

And (3) wet state testing: and (3) soaking the cured sample in 63 ℃ water for 3h, airing, and testing the tensile shear strength by using a universal material testing machine. Tensile shear strengths of 2.5MPa, 2.1MPa, 3.2MPa were obtained by dividing the readings on the aluminum sheet, pigskin and wood substrates by the area of the overlap region.

The results show that the tensile shear strength of the nano adhesive on aluminum sheets, pigskins and wood substrates is more than 2MPa in a dry and wet state, and the nano adhesive has good adhesive property.

Examples 3 and 4 were tested in the same manner and gave results similar to example 2.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.