A silk protein-based underwater adhesive and its preparation method

Abstract

The present invention relates to a silk fibroin-based underwater adhesive and a preparation method thereof. The method of the present invention uses natural silk as a raw material. After degummed silk is dissolved in a formic acid solution of inorganic salt, the silk fibroin / inorganic salt / formic acid solution is then coated on the part of the substrate that needs to be adhered, and immersed in water to obtain an adhesive that can adhere to the surfaces of various substrates underwater. The underwater adhesive prepared by the present invention is simpler in preparation, more convenient to use, lower in cost, green and environmentally friendly compared with other underwater adhesives, and has excellent adhesion ability. At the same time, the underwater adhesive prepared by the present invention has a wide range of raw material sources, can be rapidly degraded under certain conditions, has a certain promoting effect on resource and environmental protection, and has broad application prospects in the fields of packaging materials, medical materials, ship materials, etc.

Description

Technical Field

[0001] The present invention belongs to the technical fields of adhesives and packaging materials, and particularly relates to a silk protein-based underwater adhesive and a preparation method thereof. Background Art

[0002] Underwater adhesives have broad application prospects in military, industrial, biomedical fields, etc. For example, in the biomedical field, they are used to promote wound healing, stop bleeding, and tissue adhesion; in the industrial field, they are used for the repair of ships, dams, and pipelines. Inspired by marine organisms such as barnacles, mussels, and worms, many underwater adhesives have been developed and put into use. Currently, the preparation of underwater adhesives usually requires cumbersome and complex chemical synthesis or chemical modification, resulting in high production costs and certain environmental pollution; at the same time, the biocompatibility and degradability of the adhesives are poor. In addition, most underwater adhesives require a long curing time to achieve high bonding strength, and the bonded part usually becomes hard and basically loses flexibility, which to a certain extent limits their practical applications. Summary of the Invention

[0003] The purpose of the present invention is to provide a silk protein-based underwater adhesive with simple preparation and excellent performance and a preparation method thereof.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] The present invention provides a silk protein-based underwater adhesive precursor solution. The degummed silk is dissolved in an inorganic salt / anhydrous formic acid solution at a certain ratio to obtain a silk protein / inorganic salt / anhydrous formic acid solution, which is the silk protein-based underwater adhesive precursor solution that can be used underwater.

[0006] In an embodiment of the present invention, the concentration of the silk protein in the inorganic salt / anhydrous formic acid solution is 0.05 - 0.25 g / mL.

[0007] In an embodiment of the present invention, after the degummed silk is dissolved in the inorganic salt / formic acid solution, the mass ratio of the inorganic salt to the silk protein is 1:10 - 1:1.

[0008] In an embodiment of the present invention, the inorganic salt is selected from one or a mixture of several of lithium bromide, calcium chloride, calcium bromide, zinc chloride, magnesium chloride, lithium thiocyanate, sodium thiocyanate, magnesium thiocyanate, or calcium nitrate.

[0009] In an embodiment of the present invention, the inorganic salt / anhydrous formic acid solution is obtained by dissolving the inorganic salt in anhydrous formic acid.

[0010] In one embodiment of the present invention, the degummed silk refers to the degummed silk obtained by degumming mulberry silk cocoons using conventional degumming methods such as sodium carbonate and sodium bicarbonate.

[0011] In one embodiment of the present invention, it is preferred to use sodium bicarbonate to degum mulberry silk cocoons.

[0012] In one embodiment of the present invention, the method of using sodium bicarbonate to degum mulberry silk cocoons is as follows: Place the cocoons in a boiling sodium bicarbonate solution and boil twice, with the time for each time preferably being 30 minutes, aiming to remove the sericin protein on the surface of the silk fibers.

[0013] The present invention also provides a method for preparing a silk protein-based underwater adhesive precursor solution. Dissolve the degummed silk in an inorganic salt / anhydrous formic acid solution to obtain a silk protein / inorganic salt / anhydrous formic acid solution, which is the silk protein-based underwater adhesive precursor solution that can be used underwater.

[0014] The present invention also provides a method for preparing a silk protein-based underwater adhesive. Apply the obtained silk protein / inorganic salt / anhydrous formic acid solution to the part of the material that needs to be bonded, and then immerse the bonded part in water. When the formic acid is displaced by water, a silk protein-based underwater adhesive with excellent adhesion performance can be formed.

[0015] The present invention also provides a silk protein-based underwater adhesive prepared based on the above method.

[0016] The adhesive prepared by the present invention has good adhesion performance underwater and excellent adhesion to the surfaces of different materials, and its bonding strength is 150 - 300 kPa.

[0017] Silk is a natural polymer material with a long history. Due to its excellent mechanical properties, biocompatibility, and biodegradability, silk and corresponding silk protein materials have a wide range of application scenarios in many aspects. Because silk protein contains a large number of hydrophobic amino acids such as glycine and alanine, as well as some hydrophilic amino acids such as glutamic acid, it endows it with unique amphiphilicity, enabling it to regulate the adhesion and cohesion of the adhesive, thereby ensuring the stability of the adhesive in water.

[0018] In the present invention, silk fibroin is dissolved in an inorganic salt / formic acid solution, and then the obtained silk fibroin / inorganic salt / formic acid solution is coated on the bonding site and immersed in water, thereby obtaining an adhesive that can adhere to the surfaces of various substrates underwater. The silk fibroin molecular chains can maintain a relatively free and extended state in the inorganic salt / formic acid solution, thus ensuring strong interactions (such as hydrogen bonds and hydrophobic interactions) with the substrate. When the silk fibroin / inorganic salt / formic acid solution is immersed in water, due to the replacement of formic acid in the system by water, the silk fibroin undergoes a conformational change to form a silk fibroin gel with high strength, thereby bonding the substrates together. In addition, since silk fibroin contains a large number of hydrophobic amino acid residues, it can inhibit the swelling of the silk fibroin gel in water, avoiding the weakening of the cohesive force and the damage of the bonding interface caused by swelling stress, so that the silk fibroin-based underwater adhesive has excellent bonding ability. In addition, the silk fibroin-based underwater adhesive of the present invention has rich sources, simple preparation, environmental friendliness, low cost, energy saving and high efficiency, and can be rapidly degraded under certain conditions, which has a certain promoting effect on resource and environmental protection, so it has broad application prospects.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The present invention adopts the solvent replacement method to achieve the rapid preparation of an underwater adhesive and simultaneously rapidly bond to the surface of the substrate.

[0021] (2) The present invention uses degummed silk as the main material. After the degummed silk is dissolved, silk fibroin can be obtained. The underwater adhesive based on silk fibroin has good biocompatibility and biodegradability and can be applied to the field of biomedical materials.

[0022] (3) While the underwater adhesive prepared by the present invention has strong interactions with the substrate, its own swelling degree is small, and it has higher bonding ability compared with other underwater adhesives.

[0023] (4) The preparation method of the underwater adhesive prepared by the present invention is simple and easy to implement, environmentally friendly, low cost, energy saving and high efficiency. The prepared adhesive can be rapidly degraded under certain conditions, and the raw material sources are extensive, which has a certain promoting effect on resource and environmental protection and is conducive to realizing large-scale industrial production.

[0024] (5) The underwater adhesive prepared by the present invention has broad application prospects in the fields of packaging materials, medical materials, ship materials, etc. Brief Description of the Drawings

[0025] Figure 1 It is a schematic diagram obtained by preparing a silk fibroin-based underwater adhesive.

[0026] Figure 2Demonstration of the actual effect of the silk fibroin underwater adhesive on bonding the glass surface. Detailed implementation mode

[0027] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] The test method for the bonding strength in the following examples is as follows: Use an Instron 5565 universal electronic tensile testing machine, adopt a 0.5 kN sensor, and a tensile rate of 10 mm / min for testing. The bonding substrates are all 75 mm×25 mm cuboid thin sheets, and the bonding area is all 25 mm×25 mm. The bonding strength (kPa) of the adhesive is calculated by dividing the maximum load (kN) by the bonding area (m 2 )

[0029] Example 1

[0030] Dissolve 0.5 g of anhydrous calcium chloride powder in 10 mL of formic acid to prepare a 0.05 g / mL calcium chloride / formic acid solution. Take 10 mL of the above solution and add 1 g of degummed silk to make the concentration of the silk fibroin / formic acid solution 0.10 g / mL and the mass ratio of silk fibroin / calcium chloride 2 / 1, and stir for 3 hours. Centrifuge to remove air bubbles and filter the impurities through 8 layers of gauze to obtain a transparent and clear solution as the underwater adhesive. Coat this solution on one side of the glass plate to form a uniform adhesive layer, then press another glass plate on this adhesive layer, and then immerse it in water so that the two glass plates are bonded underwater, and its bonding strength is 242±26 kPa. Similarly, the bonding strengths of the silk fibroin-based underwater adhesives prepared by this method for copper plates and polytetrafluoroethylene plates are 202±27 kPa and 143±21 kPa respectively.

[0031] Since it is considered that multiple samples need to be collected for data in the same experiment to ensure feasibility, therefore, the above data on the bonding strength refers to the average value and standard deviation of the measured values of 5 samples under the same conditions. Among them, in "242±26 kPa", 242 represents the average value and 26 represents the standard deviation. Similar explanations are made for other data.

[0032] A schematic diagram of the preparation of the silk fibroin underwater adhesive is as Figure 1 shown.

[0033] The actual effect of the silk fibroin underwater adhesive in this example on bonding the glass surface is as Figure 2 shown.

[0034] Example 2

[0035] Dissolve 0.5 g of anhydrous lithium bromide powder in 10 mL of formic acid to prepare a lithium bromide / formic acid solution with a concentration of 0.05 g / mL. Take 10 mL of the above solution and add 1 g of degummed silk to make the concentration of silk protein / formic acid solution 0.10 g / mL and the mass ratio of silk protein to lithium bromide 2 / 1. Stir for 3 hours. Centrifuge to remove air bubbles and filter the impurities with 8 layers of gauze. The transparent and clear solution obtained is used as an underwater adhesive. Coat this solution on one side of a polytetrafluoroethylene plate to form a uniform adhesive layer, then press another polytetrafluoroethylene plate on this adhesive layer, and then immerse it in water so that the two polytetrafluoroethylene plates are bonded underwater, and its bonding strength is 115 ± 22 kPa.

[0036] Example 3

[0037] Dissolve 0.25 g of anhydrous calcium chloride powder in 10 mL of formic acid to prepare a calcium chloride / formic acid solution with a concentration of 0.025 g / mL. Take 10 mL of the above solution and add 0.5 g of degummed silk to make the concentration of silk protein / formic acid solution 0.05 g / mL and the mass ratio of silk protein to calcium chloride 2 / 1. Stir for 3 hours. Centrifuge to remove air bubbles and filter the impurities with 8 layers of gauze. The transparent and clear solution obtained is used as an underwater adhesive. Coat this solution on one side of a polytetrafluoroethylene plate to form a uniform adhesive layer, then press another polytetrafluoroethylene plate on this adhesive layer, and then immerse it in water so that the two polytetrafluoroethylene plates are bonded underwater, and its bonding strength is 73 ± 5 kPa.

[0038] Example 4

[0039] Dissolve 1 g of anhydrous calcium chloride powder in 10 mL of formic acid to prepare a calcium chloride / formic acid solution with a concentration of 0.10 g / mL. Take 10 mL of the above solution and add 1 g of degummed silk to make the concentration of silk protein / formic acid solution 0.10 g / mL and the mass ratio of silk protein to calcium chloride 1 / 1. Stir for 3 hours. Centrifuge to remove air bubbles and filter the impurities with 8 layers of gauze. The transparent and clear solution obtained is used as an underwater adhesive. Coat this solution on one side of a polytetrafluoroethylene plate to form a uniform adhesive layer, then press another polytetrafluoroethylene plate on this adhesive layer, and then immerse it in water so that the two polytetrafluoroethylene plates are bonded underwater, and its bonding strength is 131 ± 25 kPa.

[0040] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A preparation method of a silk fibroin-based underwater adhesive, characterized in that, Dissolve degummed silk in an inorganic salt / anhydrous formic acid solution to obtain a silk protein / inorganic salt / anhydrous formic acid solution; apply the silk protein / inorganic salt / anhydrous formic acid solution to the part of the material that needs to be bonded, and then immerse the bonded part in water. When the formic acid is displaced by water, a silk protein-based underwater adhesive with excellent adhesion performance can be formed. The concentration of the silk protein in the inorganic salt / anhydrous formic acid solution is 0.05 - 0.25 g / mL. After the degummed silk is dissolved in the inorganic salt / formic acid solution, the mass ratio of the inorganic salt to the silk protein is 1:10 - 1:

1.

2. The preparation method of a silk fibroin-based underwater adhesive according to claim 1, characterized in that, The inorganic salt is selected from one or a mixture of several of lithium bromide, calcium chloride, calcium bromide, zinc chloride, magnesium chloride, lithium thiocyanate, sodium thiocyanate, magnesium thiocyanate, or calcium nitrate.

3. The preparation method of a silk fibroin-based underwater adhesive according to claim 1, characterized in that, The inorganic salt / anhydrous formic acid solution is obtained by dissolving the inorganic salt in anhydrous formic acid.

4. The preparation method of a silk fibroin-based underwater adhesive according to claim 1, characterized in that, The degummed silk refers to the degummed silk obtained by degumming mulberry silk cocoons using a conventional degumming method.

5. A silk fibroin-based underwater adhesive, characterized in that, Prepared by the method of claim 1.

6. The silk fibroin-based underwater adhesive according to claim 5, wherein The bonding strength of the silk protein-based underwater adhesive is 150 - 300 kPa.

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