CN110747551A - A kind of hydrogel fiber of artificial spider silk and preparation method thereof - Google Patents

Abstract

A hydrogel fiber of artificial spider silk and a preparation method thereof. The artificial spider silk is produced by polymerizing acrylic acid and silica nanoparticles to form hydrogel fibers, and then inducing fiber self-assembly through water evaporation. The artificial spider silk consists of hydrogel fibers with a core-shell structure whose mechanical properties can be enhanced by ion doping and twisting. The fiber has a tensile strength of 895 MPa and a stretchability of 44.3%, which can achieve mechanical properties comparable to spider silk. The material also has a high toughness of 370MJ m ^‑3 and a damping capacity of 95%. When used for cushioning, the hydrogel fibers exhibited only 1/9 the impact force of cotton yarn, and the rebound was negligible. This work opens up an avenue for the preparation of artificial spider silk, which can be applied in the fields of kinetic energy buffering and shock absorption.

Description

A kind of hydrogel fiber of artificial spider silk and preparation method thereof

technical field

The invention belongs to the field of bionics, and particularly relates to a hydrogel fiber of artificial spider silk and a preparation method thereof.

Background technique

Spider silk is a natural hydrogel fiber with a specific combination of properties, namely high strength, large elongation and high damping capacity, with higher toughness compared to other fiber materials. Previous studies have shown that spider silk has a core-shell structure. The core, an elastic core surrounded by a plastic outer layer, is a key part of providing the silk's mechanical properties, while the outer layer provides some protection against external environmental influences. To imitate the structural properties of spider silk, novel new fiber materials are designed and applied in the fields of shock absorption and energy absorption, such as high-rise escape ropes, life-saving nets, etc., which are of great significance in real life.

There has been some success in using man-made fibers to reproduce the superior mechanical properties of spider silk. The CNT composite fibers made of CNT and silk protein showed a breaking strength of 600 MPa, a breaking strain of 73%, and a toughness of 290 MJ m ^-3 . The supramolecular hydrogel fibers showed a breaking strength of 193 MPa, a breaking strain of 18%, and a toughness of 22.8 MJ m ^-3 . Regenerated silk protein-based rayon fibers are the most widely studied, achieving excellent mechanical properties (breaking strength 1.34 GPa, breaking strain 36% and toughness 334 MJ m ^-3 ). Although these regenerated silk protein-based fibers possess the mechanical properties of natural spider silk, it is still very difficult to prepare artificial spider silk using non-protein methods, which greatly limits the large-scale use of artificial spider silk for practical life production applications. Therefore, in order to prepare artificial spider silk with excellent mechanical properties using non-protein methods, it is required to have an accurate understanding of the structure of natural spider silk and to integrate different structural models (amorphous regions cross-linked with crystallites, helical nanofibers and core-shells) structure), which is urgently needed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, aiming at the limitations of the prior art and the use requirements in special application scenarios, to provide a hydrogel fiber of artificial spider silk and a preparation method thereof.

The technical scheme of the present invention is:

A hydrogel fiber of artificial spider silk, the fiber is a hydrogel fiber formed by the polymerization of acrylic acid and silica nanoparticles, based on the core-shell structure of natural spider silk, through polypropylene acrylic water controlled by water evaporation Synthetic spider silk fibers with core-shell structure prepared by self-assembly of gels. Features include ion doping, twisting, and core-shell structure; the core-shell structure is composed of a transparent core and an opaque shell, and from a materials point of view, the core and shell of the fiber are both composed of the same polymer (acrylic acid and silica nanoparticles), the shell has less water content than the core, the core gradually decreases and the thickness of the shell increases as the fiber is exposed to air for longer.

Fibers contain hydrogen bonds and covalent networks, the key mechanism of which is the difference between the water evaporation rates of the fiber core and fiber shell. The hydrogel consists of polyacrylic acid cross-linked with vinyl-functionalized silica nanoparticles (VSNPs). Fibers are made from the aforementioned hydrogel by stretching using wooden sticks and are reinforced by adding ions to the hydrogel (called ionic doping) and inserting twist into the fibers.

The fiber has a tensile strength of 895MPa, a stretchability of 44.3%, a modulus of 28.7GPa, a high toughness of 370MJm ^-3 and a damping capacity of 95%, showing mechanical properties comparable to natural spider silk.

A hydrogel fiber of artificial spider silk and a preparation method thereof, comprising the following steps:

Step 1: Add 20mM vinyltriethoxysilane to 30g of water and stir for 12h until the oily droplets disappear and become a transparent vinylsilane solution;

Step 2: dilute the vinylsilane solution prepared in step 1, the mass concentration is 0.1%-0.5%;

Step 3: Take 0.16M acrylic acid and 18ml diluted vinylsilane solution and stir evenly, add metal ions (Zn ²⁺ , Mg ²⁺ , Na ⁺ , K ⁺ , the concentration of metal ions is 0.02M;), add initiator Ammonium persulfate 0.01mM, passed _N2 to remove dissolved oxygen, oil bath at 40°C for 30h to obtain a transparent hydrogel;

Step 4: Dip a wooden stick with a diameter of about 0.2 mm into the hydrogel prepared in step 3, and draw the wire at a speed of 4 cm s ^-1 ; 500 micron fibers;

Step 5: Fix the two ends of the wire pulled out in step 4 on the iron frame, expose it to the air, and set it by water evaporation. The setting time is 20-350s. When the inelastic shell and the elastic core reach a mechanical balance, The length of the fiber is unchanged, that is, the hydrogel fiber of artificial spider silk is obtained;

Step 6: Twisting the fiber, the mechanical properties can be enhanced due to the flattening of the fiber and the increase of the shell;

Step 7: Dry the fibers for different times. Due to the evaporation of moisture, the core layer part gradually decreases, the shell layer thickness increases, and the mechanical properties are enhanced.

Specifically, the twist density is 1-7 turns/mm.

Specifically, the drying time of the fibers is 0-2h.

Advantages and beneficial effects of the present invention:

1. The artificial spider silk prepared by the present invention is a new type of artificial spider silk with a core-shell structure, and is also an artificial spider silk suitable for special application scenarios.

2. The present invention utilizes the difference between the water evaporation rates of the hydrogel fiber core and the fiber shell to form a core-shell structure, and the mechanical properties are enhanced as the fiber is exposed to the air for a longer time.

3. In the present invention, metal ions are introduced into the hydrogel fiber to enhance the mechanical properties by increasing the cross-linking between the polymer chains.

4. In the present invention, the hydrogel fiber is twisted. During the twisting process, the fiber becomes flat, the shell increases, and the mechanical properties increase.

Description of drawings

Fig. 1 is a laser confocal image of the artificial spider silk fibers of the present invention at different drying times.

Fig. 2 is a graph showing the mechanical properties of the artificial spider silk fibers of the present invention under different vinylsilane contents.

Fig. 3 is a graph showing the mechanical properties of the artificial spider silk fibers of the present invention under the content of 0.1% vinylsilane and different metal ions (0.02M).

Figure 4 is a metallographic microscope image of the artificial spider silk fibers of the present invention with different twist densities.

Fig. 5 is an element mapping diagram of the cross section of the artificial spider silk fiber of the present invention.

Fig. 6 is a graph showing the test results of the mechanical properties of the artificial spider silk fibers involved in the present invention, a is a stress-strain graph, and b is a graph of Young's modulus and toughness.

FIG. 7 is a graph showing the results of the energy dissipation test of the artificial spider silk fibers involved in the present invention.

Fig. 8 is a graph showing the test results of the shock absorption capability of the artificial spider silk fibers involved in the present invention.

FIG. 9 is a physical diagram of the artificial spider silk fiber according to the present invention after deformation, the deformation is restored under the condition of humidity of 60%.

Detailed ways

Example 1:

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings.

The preparation method of artificial spider silk hydrogel fiber comprises the following steps:

Step 1: Add 20 mM vinyltriethoxysilane to 30 g of water and stir for 12 hours until the oily droplets disappear and become a transparent vinylsilane solution;

Step 2: Dilute the vinylsilane solution prepared in Step 1 to different concentrations; specifically, take 101.2, 202.4, 253, 303.6, 404.8 μl in 100 ml H ₂ O and stir for 30 min; get 0.1%, 0.2%, 0.25 %, 0.3%, 0.4% vinylsilane solution;

Step 3: Take 0.16M acrylic acid and 18ml of the vinylsilane solution obtained in step 2, stir for 30min, add initiator ammonium persulfate 0.1mM, pass _N2 to remove dissolved oxygen, 40 ℃ oil bath for 30h, get a transparent hydrogel glue;

Step 4: Dip a wooden stick with a diameter of about 0.2 mm into 0.5 mm of the hydrogel prepared in Step 3, and draw at a rate of 4 cm s ^-1 to obtain fibers with a diameter of 20 microns;

Step 5: Fix the two ends of the wire pulled out in Step 4 on the iron frame, expose it to the air, and shape it by water evaporation for 20s. When the inelastic shell and the elastic core reach a mechanical balance, the length of the fiber remains unchanged;

Artificial spider silk fibers formed by self-assembly of polyacrylic acid hydrogels controlled by water evaporation have a distinct core-shell structure, wherein the core of the fiber is elastic, stretchable, and transparent; the shell of the fiber is inelastic , non-stretchable, opaque. This structure is caused by the difference in the water evaporation rate between the fiber core and shell. With the increase of the drying time of the fiber in the air, some water molecules are desorbed, and the core is transformed into a shell, and because the mechanical properties of the shell are higher than that of the core, Therefore, the mechanical properties of the entire fiber will be improved. As shown in Fig. 1, when the fibers were exposed to air for 0, 0.5, 1.0, and 2.0 h, the thickness of the core gradually decreased and the thickness of the shell gradually increased.

The artificial spider silk fiber finally obtained in this embodiment has been tested as follows:

Mechanical properties test, the hydrogel fiber with a diameter of 20 microns and containing 0.1%-0.4% VSNP was subjected to tensile test under the condition of air humidity of 40% (the tensile rate was 27.8% s ^-1 ), as shown in Figure 2 It is shown that the artificial spider silk fiber obtained in this example has a tensile strength of 127MPa and a stretchability of 73% in the content of 0.1% VSNP.

Example 2:

The preparation method of artificial spider silk hydrogel fiber comprises the following steps:

Step 1: Add 20 mM vinyltriethoxysilane to 30 g of water and stir for 12 hours until the oily droplets disappear and become a transparent vinylsilane solution;

Step 2: Dilute the vinylsilane solution prepared in Step 1 to different concentrations; specifically, take 101.2 microliters and stir in 100 ml H ₂ O for 30 min; obtain a 0.1% vinylsilane solution;

Step 3: Take 0.16M acrylic acid and 18ml of the 0.1% vinylsilane solution obtained in step 2 and stir for 30min, respectively add metal ions Zn ²⁺ , Mg ²⁺ , Na ⁺ , K ⁺ , 0.02M, and add initiator persulfuric acid Ammonium 0.1mM, N ₂ was introduced to remove dissolved oxygen, oil bath at 40°C for 30h, to obtain a transparent hydrogel;

Step 4: Dip a wooden stick with a diameter of about 0.2 mm into 0.5 mm of the hydrogel prepared in Step 3, and draw at a rate of 4 cm s ^-1 to obtain fibers with a diameter of 20 microns;

Step 5: Fix the two ends of the wire pulled out in Step 4 on the iron frame, expose it to the air, and set the shape by water evaporation for 20s. When the inelastic shell and the elastic core reach a mechanical balance, the length of the fiber does not change;

Elemental mapping analysis of the hydrogel fiber section containing 0.1% VSNP, Zn ²⁺ concentration of 0.02M, and diameter of 20 microns shows that Zn ²⁺ is evenly distributed inside the fiber, as shown in Figure 3, in water The introduction of metal ions into the gel fibers can increase the degree of cross-linking of the polymer chains, thereby enhancing the mechanical properties.

The artificial spider silk fiber finally obtained in this embodiment has been tested as follows:

Mechanical properties test, the hydrogel fibers with a diameter of 20 microns, containing 0.1wt% VSNP, different metal ions Zn ²⁺ , Mg ²⁺ , Na ⁺ , K ⁺ 0.02M were stretched under the condition of air humidity 40% Testing (stretching rate of 1.1% s ⁻¹ ), as shown in FIG. 4 , when the Zn ²⁺ concentration is 0.02M, has a tensile strength of 261 MPa and a stretchability of 49.2%.

Example 3:

The preparation method of artificial spider silk hydrogel fiber comprises the following steps:

Step 1: Add 20 mM vinyltriethoxysilane to 30 g of water and stir for 12 hours until the oily droplets disappear and become a transparent vinylsilane solution;

Step 2: Dilute the vinylsilane solution prepared in Step 1 to different concentrations; specifically, take 101.2 microliters and stir in 100 ml H ₂ O for 30 min; obtain a 0.1% vinylsilane solution;

Step 3: Take 0.16M acrylic acid and 18ml of the 0.1% vinylsilane solution obtained in step ₂ and stir for 30min, add metal ion Zn ²⁺ 0.02M, add initiator ammonium persulfate 0.1mM, pass N to remove dissolved oxygen , 40°C oil bath for 30h to obtain a transparent hydrogel;

Step 4: Dip a wooden stick with a diameter of about 0.2 mm into 0.5 mm of the hydrogel prepared in Step 3, and draw at a rate of 4 cm s ^-1 to obtain fibers with a diameter of 20 microns;

Step 5: Fix the two ends of the wire pulled out in Step 4 on the iron frame, expose it to the air, and shape it by water evaporation for 30s. When the inelastic shell and the elastic core reach a mechanical balance, the length of the fiber remains unchanged;

Step 6: Fix one end of the hydrogel fiber obtained in Step 5 on the motor, and hang a small weight on the other end for twisting;

As shown in Figure 5, the hydrogel fibers with a diameter of 20 microns were twisted, and the twist density was 1, 3, 5, and 7 turns/mm, the fibers became flat, and the inner core became opaque, and the fibers became more Like a shell, the mechanical properties are improved.

The artificial spider silk fiber finally obtained in this embodiment has been tested as follows:

1. Mechanical properties test, the hydrogel fibers with a diameter of 20 microns, containing 0.1wt% VSNP, 0.02M Zn ²⁺ , and a twist density of 7 turns/mm were stretched under the condition of air humidity 40%-100% Test (stretching rate is 27.8% s ^-1 ), as shown in a and b in Figure 6, the artificial spider silk fiber obtained in this example has a tensile strength of 895MPa, a stretchability of 44.3%, and a stretchability of 28.7GPa , showing mechanical properties comparable to those of natural spider silk.

2. Energy dissipation performance test, the hydrogel fibers with a diameter of 20 microns, containing 0.1 wt% VSNP, 0.02 M Zn ²⁺ , and a twist density of 3 turns/mm were subjected to progressive air humidity under the condition of 40%. The stretch-release cycle, as shown in FIG. 7 , the artificial spider silk fiber obtained in this example has a damping capacity of 95% and an energy dissipation of 245 MJ m ⁻³ .

3. Shock absorption performance test, tie a 20g weight to the bottom end of 100 hydrogel fibers with a diameter of 10 cm and a diameter of 20 microns, and let the weight fall freely for 15 cm under 60% humidity, as shown in Figure 8 As shown, the artificial spider silk fiber obtained in this example has an elongation of 150% with negligible rebound, and has an impact force of 0.36N, which is 8 times smaller than that of cotton thread at the same drop height. The hydrogel fibers used for this test contained 0.1 wt% VSNP, 0.02M Zn2 ⁺ , and had a twist density of 3 turns/mm.

4. Deformation recovery test: Weave hydrogel fibers with a diameter of 20 microns into a net, fix it on an iron ring, place it in an environment with a humidity of 60%, place a 200g weight on the hydrogel net, and the network deforms , remove the weight, and the gel network recovers its deformation, as shown in Figure 9. The hydrogel fibers used for this test contained 0.1 wt% VSNP, 0.02M Zn2 ⁺ , and had a twist density of 3 turns/mm.

In addition, those skilled in the relevant art can also make other changes according to the technical solution of the present invention, such as modification, equivalent replacement and improvement, etc., and the changes made according to the technical solution of the present invention should all be included within the scope of protection of the technical solution.

Claims (9)

1. The hydrogel fiber of the artificial spider silk is characterized in that the fiber is a hydrogel fiber formed by polymerizing acrylic acid and silicon dioxide nano particles, and then the fiber is prepared into the artificial spider silk fiber with a core-shell structure through self-assembly of polyacrylic acid hydrogel controlled by water evaporation, and the fiber has the characteristics of ion doping, twisting and core-shell structure; the core-shell structure consists of a transparent core and an opaque shell, from the material point of view, the core and the shell of the fiber both consist of the same polymer acrylic acid and silica nanoparticles, the shell has less water content compared with the core, the core gradually decreases and the shell gradually increases in thickness as the fiber is exposed to air for a longer time.

2. The hydrogel fiber of claim 1, wherein the core on the core-shell structure is elastic, stretchable; the shell is non-elastic.

3. The hydrogel fiber of claim 1, wherein the twisting is a process of fixing one end of the fiber on a motor and hanging a small weight on the other end to twist the fiber, and the fiber is flattened by twisting, and the inner core becomes opaque; the twisting density is 1-7 turn/mm.

4. A method of making hydrogel fibres of an artificial spider silk according to claim 1, comprising the steps of:

step 1: 20mM vinyl triethoxysilane is added into 30g water and stirred for 12h until the oily droplets disappear and become a transparent vinyl silane solution;

step 2: diluting the vinyl silane solution prepared in the step 1 to a mass concentration of 0.1-0.5%;

and step 3: taking 0.16M acrylic acid and 18ml of vinyl silane solution diluted in the step 2, stirring uniformly, adding metal ions, adding an initiator ammonium persulfate of 0.1mM, and introducing N₂Removing dissolved oxygen, and performing oil bath at 40 ℃ for 30h to obtain transparent hydrogel;

and 4, step 4: dipping a wooden stick with the diameter of 0.2mm into the hydrogel prepared in the step 3, and drawing wires;

and 5: and (4) fixing the two ends of the silk pulled out in the step (4), exposing the silk in the air, and shaping by water evaporation, wherein when the inelastic shell and the elastic core reach mechanical balance, the length of the fiber is unchanged, and the hydrogel fiber of the artificial spider silk is obtained.

5. The method for producing a hydrogel fiber according to claim 4, wherein the metal ion is Zn²⁺、Mg²⁺、Na⁺Or K⁺The concentration used was 0.02M.

6. The method for preparing hydrogel fiber according to claim 4, wherein the 0.2mm stick drawing rate is 4cm s^-1。

7. The method for preparing hydrogel fibers according to claim 4, wherein the wood stick is inserted into the hydrogel to be drawn, and fibers having a diameter of 10 to 500 μm can be obtained according to the depth of insertion into the gel.

8. The method of claim 4, wherein the setting time of the fiber is 20 to 350 seconds.

9. The method for producing a hydrogel fiber according to any one of claims 4 to 8, further comprising:

step 6: twisting the fiber with twisting density of 1-7turn/mm to enhance mechanical performance due to fiber flattening and shell increase;

and 7: drying the fiber for 0-2h, wherein the core layer is gradually reduced due to the evaporation of water, the shell layer is increased in thickness, and the mechanical property is enhanced.

Images