CN111732754B

CN111732754B - Three-dimensional scaffold with multistage holes, three-dimensional functional scaffold and preparation method thereof

Info

Publication number: CN111732754B
Application number: CN202010625729.3A
Authority: CN
Inventors: 杨伟; 喻鹏; 冯兰祥; 查湘军; 孙小蓉; 王宇; 杨鸣波
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2020-07-02
Filing date: 2020-07-02
Publication date: 2021-04-23
Anticipated expiration: 2040-07-02
Also published as: CN111732754A

Abstract

The invention relates to a three-dimensional bracket with multistage holes, a three-dimensional functional bracket and a preparation method thereof, belonging to the field of functional composite materials. The invention provides a preparation method of a three-dimensional scaffold composite material with a multistage hole structure, which comprises the following steps: uniformly stirring and mixing a rigid polymer and polyvinylpyrrolidone by using a solvent to prepare a uniform polymer solution serving as a precursor solution, and then inducing the precursor solution to self-assemble in a certain external environment to form the three-dimensional scaffold composite material with the multistage hole structure; wherein the external environmental conditions include: the temperature is 0-80 ℃, and the humidity is 50-100%. The invention firstly provides a method for self-assembling rigid polymer and PVP by environmental induction, and the three-dimensional scaffold material with a multistage hole structure can be obtained, and the porous scaffold has a stable structure, a uniform and complete macroporous structure and a large number of mesopores and micropores.

Description

Three-dimensional scaffold with multistage holes, three-dimensional functional scaffold and preparation method thereof

Technical Field

The invention relates to a three-dimensional bracket with multistage holes, a three-dimensional functional bracket and a preparation method thereof, belonging to the field of functional composite materials.

Background

With the continuous development of human society, the application scenes of functional scaffold materials are more and more, for example, the fields of bone tissue replacement materials, adsorption materials, super capacitors, battery electrodes and the like. In these fields, the functional requirements for the stent material are also increasing. How to enable the scaffold material to have better performance in respective fields is a good solution for the three-dimensional scaffold with the multi-stage hole structure. Due to the fact that gaps with different sizes exist in the support, the holes with different sizes can exert corresponding functional effects, and the functional support can exert better effects due to the cooperation of the functional effects.

For example, in the bone tissue replacement material, the macropores with the diameter of about 100um can provide living places for osteoblasts well, and are also suitable for the growth of cells. Smaller mesopores and micropores provide attachment points for adhesion of osteoblasts, and the small pore system can accelerate the exchange of substances called as an extracellular microenvironment of osteoblasts, provide a better living environment for osteoblasts, and rapidly proliferate and differentiate the osteoblasts. The macropores in the adsorbing material mainly provide better infiltration capacity for the material, so that the solution in the stent is smoothly exchanged, and the micropores can provide more specific surface area to provide more action surfaces for adsorption so as to increase the adsorption capacity of the stent.

In the electrochemical field, such a multi-stage pore structure still has its unique advantages. For example, in the application of the positive electrode material of the lithium-sulfur battery, firstly, the multi-level hole bracket has certain deformation capacity due to the existence of the multi-level holes, so that the structure is very stable; the macropores in the scaffold are beneficial for electrolyte permeation and ion transport. The mesopores and micropores in the scaffold can prevent the loss of active substances and shuttle effect. Therefore, the electrode material prepared by the bracket with the multistage holes has higher capacity, good rate capability and cycling stability. The super capacitor material has very strict requirements on the material, and the material is required to have a very high specific surface area while the gap is required to be perfected; the bracket with the multilevel cavity structure can well meet the requirements, the macropores can well meet the infiltration of electrolyte, and the mesopores in large quantity can provide a plurality of active sites and a large amount of specific surface area, thereby greatly increasing the performance of the super capacitor.

In summary, the three-dimensional porous gel with a multi-level pore structure has the significance and advantages of practical application in many fields, and the conventional methods for preparing the three-dimensional porous gel with the multi-level pore structure are troublesome, such as a template method and an etching method. Therefore, it is very meaningful and urgent to develop a method for simply preparing a three-dimensional porous gel having a multi-stage pore structure on a large scale.

Disclosure of Invention

In view of the above-mentioned drawbacks, the present invention aims to provide a method for preparing a three-dimensional porous scaffold having a hierarchical pore structure, which can realize different applications of the porous scaffold by changing functional particles added to the system, and which is simple and can realize mass production.

The technical scheme of the invention is as follows:

the first technical problem to be solved by the invention is to provide a preparation method of a three-dimensional scaffold composite material with a multistage pore structure, wherein the preparation method comprises the following steps: uniformly stirring a rigid polymer and polyvinylpyrrolidone (PVP) by using a solvent to prepare a uniform polymer solution serving as a precursor solution, and then inducing the precursor solution to self-assemble in a certain external environment to form the three-dimensional scaffold composite material with the multistage hole structure; wherein the external environmental conditions include: the temperature is 0-80 ℃, and the humidity is 50-100%.

Further, in the above method, the mass ratio of the rigid polymer to the polyvinylpyrrolidone is 10: 1-1: 2; preferably, the ratio of 9: 1-3: 1. in the present invention, when the rigid polymer is more than PAN, the multistage porous structure is not formed in the limit, which is the case of pure PAN, as shown in fig. 2a, but is only porous; when the PVP is too much, the formed macropores are too large, so that the mechanical property of the stent is poor.

Further, the external environment further includes: applying flowing air flow with the flow rate of 0.1-3 m³/s。

Preferably, the temperature in the external environment is 0-60 ℃.

Further, the three-dimensional scaffold composite material has a multi-stage pore structure, which means that the three-dimensional scaffold composite material has a uniform macroporous structure, and mesoporous and microporous structures exist on the walls of the macroporous pores. The macropores are pores with a size of more than 50nm, the pores with a size of 2-50nm are mesopores, and the micropores with a size of less than 2nm are micropores.

Further, the rigid polymer is Polyacrylonitrile (PAN), Polymethylmethacrylate (PMMA) or polylactic acid (PLA).

Further, in the method, the mass fraction of the polymer in the polymer solution is 3 to 25 wt%.

Further, in the above method, the solvent is at least one of DMF (dimethylformamide), DMSO, or NMP.

Further, in the above method, the method of uniformly mixing the rigid polymer and the polyvinylpyrrolidone with a solvent to obtain a uniform polymer solution comprises: adding rigid polymer powder and polyvinylpyrrolidone powder into a solvent, and magnetically stirring for 10-15 h (preferably 12h) to obtain a uniform polymer solution.

Further, in the above method, the method of precipitating the composite scaffold material from the precursor solution in a certain external environment comprises: uniformly blade-coating the precursor solution on a film forming die, and inducing the porous support material to be separated out by utilizing the external environment; and washing the separated porous scaffold material with distilled water completely, and freeze-drying to obtain the three-dimensional scaffold composite material with the multi-stage pore structure.

Further, the film forming mould is an aluminum foil, a glass plate or a polytetrafluoroethylene film; any film-forming mold may be used.

The second technical problem to be solved by the invention is to provide a three-dimensional scaffold material with a multistage pore structure, which is prepared by adopting the method.

The third technical problem to be solved by the present invention is to provide a method for preparing a three-dimensional functional scaffold material with a multi-stage pore structure, wherein the preparation method comprises: uniformly stirring and mixing a rigid polymer and polyvinylpyrrolidone (PVP) by using a solvent to prepare a uniform polymer solution, and dropwise adding the functional particle dispersion liquid into the polymer solution and stirring to obtain a uniformly mixed precursor solution; then, inducing the precursor solution in a certain external environment to self-assemble to form the three-dimensional functional bracket material with the multi-level hole structure; wherein the external environmental conditions include: the temperature is 0-80 ℃, and the humidity is 50-100%.

Further, in the above method, the mass ratio of the rigid polymer to the polyvinylpyrrolidone is 1: 2-10: 1; preferably 3: 1-9: 1.

Further, in the above method, the functional particles in the functional particle dispersion liquid are conductive particles, adsorption particles, or osteogenic factors. In the invention, any functional particles can be added according to the actual functional requirements, such as conductive particles, adsorption particles or osteogenic factors; the addition amount can be adjusted according to actual needs.

Further, in the above method, the mass concentration of the polymer in the precursor liquid is 3 to 25wt%, and the mass concentration of the functional particles is 0.01 to 20 wt%.

Still further, the functional particles are selected from: carbon nanotubes, graphene, carbon black or TiO₂At least one of (1).

Further, in the above method, the functional particle dispersion is prepared by adding the functional particles into the corresponding solvent, magnetically stirring for at least 1h, and ultrasonically treating for at least 2 h.

Further, the mass of the functional particles in the functional particle dispersion is 0.1 to 30wt% of the mass of the solvent.

Further, in the above method, the method of dropping the functional particle dispersion into the polymer solution and stirring to obtain a uniformly mixed precursor solution includes: dropwise adding the functional particle dispersion liquid into the polymer solution under high-speed stirring, and continuously stirring at high speed for at least 10min to obtain uniform precursor liquid; wherein the high-speed stirring speed is more than 8000 r/min.

The fourth technical problem to be solved by the invention is to provide a three-dimensional functional scaffold material with a multistage pore structure, which is prepared by adopting the preparation method.

The invention has the beneficial effects that:

the invention firstly provides a three-dimensional scaffold material with a multi-stage pore structure, which is obtained by a rigid polymer (such as PAN) and PVP through an environment-induced self-assembly method; the three-dimensional porous scaffold with the multistage pore structure has the following advantages:

(1) the porous support has stable structure, uniform and perfect macroporous structure and a large number of mesopores and micropores.

(2) The pore diameter of the macropore of the bracket can be regulated and controlled according to the proportion of the polymer in the precursor liquid and the forming environmental conditions, and the mesopore and micropore can be regulated by adding functional particles.

(3) The preparation method is simple and feasible, and can realize large-scale production.

(4) The functional particles can be self-assembled together into the porous scaffold during the formation of the porous scaffold, together forming a perfect network structure.

Description of the drawings:

FIG. 1 is a SEM photograph and gel formation time chart of samples obtained in examples 1-8, in which FIG. 1(a) is F-A/V-0 (example 7), FIG. 1(b) is F-A/V-25 (example 8), FIG. 1(c) is A/V-60/0 (example 1), FIG. 1(d) is A/V-60/25 (example 2), FIG. 1(e) is A/V-60/60 (example 3), FIG. 1(F) is A/V-100/0 (example 4), FIG. 1(g) is A/V-100/25 (example 5), and FIG. 1(h) is A/V-100/60 (example 6).

FIG. 2 is an SEM image of samples from examples 9-13: FIG. 2(a) A/V-1:0 (example 9), FIG. 2(b) A/V-9:1 (example 10), FIG. 2(c) A/V-7:1 (example 11), FIG. 2(d) A/V-5:1 (example 12), FIG. 2(e) A/V-3:1 (example 13).

FIG. 3 is an SEM image of samples obtained in examples 14 and 16 to 17: FIG. 3(a, d) C/A/V-1:0 (example 14), FIG. 3(b, e) C/A/V-7:1 (example 16), FIG. 3(C, f) C/A/V-5:1 (example 17).

FIG. 4 is a graph showing the results of pore size distribution and specific surface area for the samples obtained in example 11 and examples 14 to 17: FIG. 4(a) A/V-7:1 (example 11), FIG. 4(b) C/A/V-7:1 (example 16).

Fig. 5 shows the result of cycle performance of the material obtained in example 19 for a positive electrode material.

Detailed Description

The invention discloses a method for preparing a three-dimensional scaffold with multilevel pores, which can be used for preparing a porous three-dimensional scaffold simply and massively; only the precursor solution is prepared and is subjected to proper environmental induction, and the three-dimensional porous gel can be separated out from the solution in a self-assembly mode. In the precursor liquid, various functional particles such as conductive particles, adsorption particles, osteogenic factors and the like can be introduced, and the three-dimensional porous scaffold can be functionalized. The multi-stage hole three-dimensional bracket prepared by the method has a uniform macroporous structure, and a large number of mesopores and micropores exist on the wall of the macroporous hole. The three-dimensional porous scaffold prepared by the method is expected to be applied in a plurality of fields such as energy storage, adsorption and the like.

The following examples are given to further illustrate the embodiments of the present invention and are not intended to limit the scope of the present invention.

Example 1:

(1) preparing Polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP) composite solution: adding 0.5g of PAN and PVP powder into 10ml of DMF solution according to the mass ratio of 5:1, and magnetically stirring for 12 hours to obtain a uniform polymer solution.

(2) And (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite bracket to be separated out under the conditions of humidity of 60% and no wind at the temperature of 0 ℃; and washing the DMF solvent in the precipitated porous scaffold completely with distilled water, and freeze-drying to obtain the final composite scaffold A/V-60/0.

Example 1:

(1) preparing a PAN/PVP compound solution: adding 0.5g of PAN and PVP powder into a 10ml of DMF solution according to the mass ratio of 5:1, and magnetically stirring for 12 hours to obtain a uniform polymer solution;

(2) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out under the conditions that the humidity is 60% and the temperature is 25 ℃ and no wind exists; and washing the DMF solvent in the precipitated porous scaffold completely with distilled water, and freeze-drying to obtain the final composite scaffold A/V-60/25.

Example 3:

(1) preparing a PAN/PVP compound solution: adding 0.5g of PAN and PVP powder into 10ml of DMF solution according to the mass ratio of 5:1, and magnetically stirring for 12 hours to obtain a uniform polymer solution.

(2) And (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite bracket to be separated out under the conditions that the humidity is 60% and the temperature is 60 ℃ and no wind exists; and washing the DMF solvent in the precipitated porous scaffold completely with distilled water, and freeze-drying to obtain the final composite scaffold A/V-60/60.

Example 4:

(2) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite bracket to be separated out under the conditions that the humidity is 100% and the temperature is 0 ℃ and no wind exists; and washing the DMF solvent in the precipitated porous scaffold completely with distilled water, and freeze-drying to obtain the final composite scaffold A/V-100/0.

Example 5:

(2) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out under the conditions that the humidity is 100% and the temperature is 25 ℃ and no wind exists; and washing the DMF solvent in the precipitated porous scaffold completely with distilled water, and freeze-drying to obtain the final composite scaffold A/V-100/25.

Example 6:

(2) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite bracket to be separated out under the conditions that the humidity is 100% and the temperature is 60 ℃ and no wind exists; and washing the DMF solvent in the precipitated porous scaffold completely with distilled water, and freeze-drying to obtain the final composite scaffold A/V-100/60.

Example 7:

(2) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 0 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water, and freeze-drying to obtain the final composite scaffold F-A/V-0.

Example 8:

(2) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 25 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water, and freeze-drying to obtain the final composite scaffold F-A/V-25.

Example 9:

(1) preparing a PAN composite solution: adding 0.5g of PAN into 10ml of DMF solution, and magnetically stirring for 12 hours to obtain uniform polymer solution;

(2) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 20 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water completely, and freeze-drying to obtain the final composite scaffold A/V-1: 0.

Example 10:

(1) preparing a PAN/PVP compound solution: adding 0.5g of PAN and PVP powder into a 10ml of DMMF solution according to the mass ratio of 9:1, and magnetically stirring for 12 hours to obtain a uniform polymer solution;

(2) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 20 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water completely, and freeze-drying to obtain the final composite scaffold A/V-9: 1.

Example 11:

(1) preparing a PAN/PVP compound solution: adding 0.5g of PAN and PVP powder into a 10ml of DMF solution according to the mass ratio of 7:1, and magnetically stirring for 12 hours to obtain a uniform polymer solution;

(2) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 20 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water completely, and freeze-drying to obtain the final composite scaffold A/V-7: 1.

Example 12:

(2) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 20 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water completely, and freeze-drying to obtain the final composite scaffold A/V-5: 1.

Example 13:

(1) preparing a PAN/PVP compound solution: adding 0.5g of PAN and PVP powder into a 10ml of DMMF solution according to the mass ratio of 3:1, and magnetically stirring for 12 hours to obtain a uniform polymer solution;

(2) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 20 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water completely, and freeze-drying to obtain the final composite scaffold A/V-3: 1.

Example 14

(1) Preparing a PAN composite solution: adding 0.5g of PAN powder into 10ml of DMF solution, and magnetically stirring for 12 hours to obtain a uniform polymer solution;

(2) preparing a functional particle dispersion: adding 0.6g of carbon nano tube into 10ml of DMMF solution, magnetically stirring for 1h, and performing ultrasonic treatment for 2h to obtain uniform functional particle dispersion liquid;

(3) preparing a precursor solution: under high-speed stirring, dropwise adding the functional particle dispersion liquid into the PAN composite polymer solution, and continuously stirring at high speed for 10min to obtain uniform precursor liquid;

(4) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 20 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water completely, and freeze-drying to obtain the final composite scaffold C/A/V-1: 0.

Example 15

(3) preparing a precursor solution: dropwise adding the functional particle dispersion liquid into the PAN/PVP composite polymer solution under high-speed stirring, and continuously stirring at high speed for 10min to obtain uniform precursor liquid;

(4) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 20 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water completely, and freeze-drying to obtain the final composite scaffold C/A/V-9: 1.

Example 16

(4) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 20 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water completely, and freeze-drying to obtain the final composite scaffold C/A/V-7: 1.

Example 17

(4) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 20 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water completely, and freeze-drying to obtain the final composite scaffold C/A/V-5: 1.

Example 18

(3) preparing a precursor solution: and dropwise adding the functional particle dispersion liquid into the PAN/PVP composite polymer solution under high-speed stirring, and continuously stirring at high speed for 10min to obtain a uniform precursor liquid.

(4) And (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 20 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water completely, and freeze-drying to obtain the final composite scaffold C/A/V-3: 1.

Example 19

(2) preparing a functional particle dispersion: adding 0.3g of carbon nano tube and 1g of active carbon-sulfur composite particles into a 10ml of DMMF solution, magnetically stirring for 1 hour, and performing ultrasonic treatment for 2 hours to obtain a uniform functional particle dispersion liquid;

(4) and (3) environment-induced precipitation of the composite scaffold: uniformly blade-coating the precursor solution on an aluminum foil, and inducing the composite support to be separated out in a fume hood with the humidity of 60% and the temperature of 20 ℃; and washing the DMF solvent in the precipitated porous scaffold with distilled water completely, and freeze-drying to obtain the final composite scaffold SC/A/V-7: 1.

And (3) performance testing:

the SEM pictures and gel formation times of the samples obtained in examples 1-8 are shown in FIG. 1, in which FIG. 1(a) F-A/V-0 (example 7), FIG. 1(b) F-A/V-25 (example 8), FIG. 1(c) A/V-60/0 (example 1), FIG. 1(d) A/V-60/25 (example 2), FIG. 1(e) A/V-60/60 (example 3), FIG. 1(F) A/V-100/0 (example 4), FIG. 1(g) A/V-100/25 (example 5), FIG. 1(h) A/V-100/60 (example 6).

From the electron micrograph of fig. 1, it can be seen that the environment in which the scaffold is formed has a great influence on the morphology of the scaffold and the time required to form the scaffold: with the increase of the forming temperature, the pore diameter of the bracket is slightly increased, and meanwhile, the pore diameter of the bracket is also increased by the increase of the humidity; too high a temperature will result in an imperfect structure of the stent being formed, and too low a temperature will result in a considerable increase in the time required to form the stent; in the presence of a flowing gas stream, the time required to form the stent is greatly reduced and a well-structured stent can be formed.

FIG. 2 is an SEM image of samples from examples 9-13: FIG. 2(a) A/V-1:0 (example 9), FIG. 2(b) A/V-9:1 (example 10), FIG. 2(c) A/V-7:1 (example 11), FIG. 2(d) A/V-5:1 (example 12), FIG. 2(e) A/V-3:1 (example 13). As can be seen from fig. 2, the ratio of the polymer in the precursor solution for forming the stent also has a great influence on the structure of the stent: when all the precursor liquid is PAN, the scaffold structure is a general spongy structure (figure 2a), after PVP is introduced into the precursor liquid, the scaffold structure is gradually converted into a honeycomb shape, and the pore diameter of the scaffold is gradually increased along with the increase of the content of the PVP; in the formed honeycomb scaffold structure, whether the surface of the large hole or the inside of the large hole is provided with a smaller hole structure woven by fine microfiber bundles, which shows that the invention successfully synthesizes the porous scaffold with a multistage hole structure.

FIG. 3 is an SEM image of samples obtained in examples 14, 16-17 at different magnifications: FIG. 3(a, d) C/A/V-1:0 (example 14), FIG. 3(b, e) C/A/V-7:1 (example 16), FIG. 3(C, f) C/A/V-5:1 (example 17). As can be seen from fig. 3, in example 14, although gel is formed when only PAN is present in the polymer, the gel does not have a multi-stage pore structure, but has a simple network structure (see fig. 3a and 3 d); in addition, as can be seen from fig. 3, as with no carbon nanotube, the macroporous structure of the porous gel is still stably formed after the carbon nanotube is added; the difference is that the pore closures are uniformly covered with a layer of carbon nanotubes, which shows that when the polymer is self-assembled to form the porous support, the carbon nanotubes are self-assembled to the porous support at the same time to form a perfect conductive network.

FIG. 4 is a graph showing the results of pore size distribution and specific surface area for the samples obtained in example 11 and example 16: FIG. 4(a) A/V-7:1 (example 11), FIG. 4(b) C/A/V-7:1 (example 16). As can be seen from fig. 4, by comparing the specific surface area and the pore size distribution of whether the carbon nanotubes are introduced into the scaffold, a large amount of mesopores of 40 to 60nm exist in the porous scaffold without adding the nanoparticles; after the carbon nano tube is introduced, the size of the mesopores is greatly reduced to reach the level close to the micropores, the specific surface area of the support is greatly improved, and the reached value is far higher than that of a pure polymer support and the carbon nano tube.

The composite scaffold obtained in example 19 was pressed under a pressure of 8Mpa and cut with a cutter to obtain a positive electrode wafer with a diameter of 1.1cm, and the electrode plate was assembled into a battery of a size 2032 and subjected to electrochemical performance test; fig. 5 shows the result of cycle performance of the material obtained in example 19 for a positive electrode material. As can be seen from fig. 5, the scaffold prepared by the method of the present invention has good cycle performance when applied to a positive electrode material of a lithium-sulfur battery: has a specific capacity of 480mAh/g even after 1000 cycles of 0.1C; this is due to the multilevel pore structure of the scaffold, the stable physical structure and the perfect conductive network formed by the added carbon nanotubes during the self-assembly process.

Claims

1. A preparation method of a three-dimensional scaffold composite material with a multistage hole structure is characterized by comprising the following steps: uniformly stirring and mixing a rigid polymer and polyvinylpyrrolidone by using a solvent to prepare a uniform polymer solution serving as a precursor solution, and then inducing the precursor solution to self-assemble in a certain external environment to form the three-dimensional scaffold composite material with the multistage hole structure; wherein the external environmental conditions include: the temperature is 0-80 ℃, and the humidity is 50-100%; the rigid polymer is polyacrylonitrile, and the mass ratio of the rigid polymer to the polyvinylpyrrolidone is 1: 2-10: 1.

2. the method for preparing the three-dimensional scaffold composite material with the multistage pore structure as claimed in claim 1, wherein the mass ratio of the rigid polymer to the polyvinylpyrrolidone is 3: 1-9: 1.

3. the method for preparing the three-dimensional scaffold composite material with the multistage pore structure as claimed in claim 1 or 2, wherein the external environment further comprises: applying flowing air flow with the flow rate of 0.1-3 m³/s。

4. The method for preparing the three-dimensional scaffold composite material with the hierarchical pore structure according to claim 1 or 2, wherein the three-dimensional scaffold composite material has the hierarchical pore structure means that the three-dimensional scaffold composite material has a uniform macroporous structure, and mesoporous and microporous structures exist on walls of the macroporous pores.

5. The method for preparing the three-dimensional scaffold composite material with the multistage pore structure as claimed in claim 1 or 2, wherein the mass fraction of the polymer in the polymer solution is 3-25 wt%.

6. The method for preparing the three-dimensional scaffold composite material with the multistage pore structure according to claim 1 or 2, wherein the solvent is at least one of DMF, DMSO or NMP.

7. The preparation method of the three-dimensional scaffold composite material with the multistage pore structure according to claim 1 or 2, wherein the method for uniformly mixing the rigid polymer and the polyvinylpyrrolidone by using a solvent to prepare a uniform polymer solution comprises the following steps: adding rigid polymer powder and polyvinylpyrrolidone powder into a solvent, and magnetically stirring for 10-15 h to obtain a uniform polymer solution.

8. The preparation method of the three-dimensional scaffold composite material with the multistage hole structure as claimed in claim 1 or 2, wherein the method for precipitating the composite scaffold material from the precursor solution in a certain external environment comprises the following steps: uniformly blade-coating the precursor solution on a film forming die, and inducing the porous support material to be separated out by utilizing the external environment; and washing the separated porous scaffold material with distilled water completely, and freeze-drying to obtain the three-dimensional scaffold composite material with the multi-stage pore structure.

9. The method for preparing the three-dimensional scaffold composite material with the multistage pore structure as claimed in claim 8, wherein the film forming mold is an aluminum foil, a glass plate or a polytetrafluoroethylene film.

10. A three-dimensional scaffold material with a multistage pore structure, which is prepared by the method of any one of claims 1 to 9.

11. A preparation method of a three-dimensional functional scaffold material with a multi-stage hole structure is characterized by comprising the following steps: uniformly stirring and mixing a rigid polymer and polyvinylpyrrolidone by using a solvent to prepare a uniform polymer solution, and dropwise adding the functional particle dispersion liquid into the polymer solution and stirring to obtain a uniformly mixed precursor solution; then, inducing the precursor solution in a certain external environment to self-assemble to form the three-dimensional functional bracket material with the multi-level hole structure; wherein the external environmental conditions include: the temperature is 0-80 ℃, and the humidity is 50-100%; the rigid polymer is polyacrylonitrile, and the mass ratio of the rigid polymer to the polyvinylpyrrolidone is 1: 2-10: 1.

12. the method for preparing the three-dimensional functional scaffold material with the multistage pore structure according to claim 11, wherein the mass ratio of the rigid polymer to the polyvinylpyrrolidone is 3: 1-9: 1.

13. the method for preparing a three-dimensional functional scaffold material with a multistage pore structure as claimed in claim 11 or 12, wherein the external environment further comprises: applying flowing air flow with the flow rate of 0.1-3 m³/s。

14. The method for preparing a three-dimensional functional scaffold material with a hierarchical pore structure as set forth in claim 11 or 12, wherein the functional particles in the functional particle dispersion are conductive particles, adsorbent particles or osteogenic factors.

15. The method for preparing a three-dimensional functional scaffold material with a hierarchical pore structure according to claim 11 or 12, wherein the mass concentration of the polymer in the precursor solution is 3-25 wt%, and the mass concentration of the functional particles is 0.01-20 wt%.

16. The method for preparing the three-dimensional functional scaffold material with the hierarchical pore structure according to claim 15, wherein the functional particles are selected from the group consisting of: at least one of carbon nanotubes, graphene, carbon black, or titanium dioxide.

17. The method for preparing a three-dimensional functional scaffold material with a hierarchical pore structure according to claim 11 or 12, wherein the mass of the functional particles in the functional particle dispersion is 0.1-30 wt% of the mass of the solvent.

18. The method for preparing the three-dimensional functional scaffold material with the hierarchical pore structure according to claim 11 or 12, wherein the method for dropping the functional particle dispersion into the polymer solution and stirring to obtain the uniformly mixed precursor solution comprises the following steps: dropwise adding the functional particle dispersion liquid into the polymer solution under high-speed stirring, and continuously stirring at high speed for at least 10min to obtain uniform precursor liquid; wherein the high-speed stirring speed is more than 8000 r/min.

19. A three-dimensional functional scaffold material with a multistage pore structure, which is prepared by the method of any one of claims 11 to 18.