阅读说明：本技术 一种兼具高比表面积与大孔径的柔性多孔SiO2纳米纤维膜的制备方法 (Flexible porous SiO with high specific surface area and large aperture2Preparation method of nanofiber membrane ) 是由 单浩如 傅秋霞 刘其霞 张伟 季涛 高强 张瑜 于 2021-06-28 设计创作，主要内容包括：本发明公开了一种兼具高比表面积与大孔径的柔性多孔SiO-(2)纳米纤维膜的制备方法,具体为将硅源、分散剂依次加入到溶剂中,搅拌后加入发泡剂,继续搅拌一段时间后制得前驱体溶液；采用静电纺丝技术将前驱体溶液制备成前驱体纤维膜；将前驱体纤维膜先在空气气氛中低温慢速煅烧,然后升至高温继续煅烧,得到兼具高比表面积与大孔径的柔性多孔SiO-(2)纳米纤维膜。本发明方法有效解决了现有技术中多孔SiO-(2)纤维存在的脆性大、易断裂、孔径小、孔体积小等问题,所获得的柔性多孔SiO-(2)纳米纤维膜具有柔性好、比表面积高、孔径大、孔体积大、孔结构可控等特性,在国防军工、环境净化、吸附分离、离子交换等领域具有广阔的应用前景。(The invention discloses a flexible porous SiO with high specific surface area and large aperture 2 The preparation method of the nanofiber membrane comprises the steps of sequentially adding a silicon source and a dispersing agent into a solvent, stirring, adding a foaming agent, and continuously stirring for a period of time to prepare a precursor solution; preparing a precursor fiber film from the precursor solution by adopting an electrostatic spinning technology; firstly, the precursor fiber film is slowly calcined at low temperature in air atmosphere, and thenHeating to high temperature and continuously calcining to obtain the flexible porous SiO with high specific surface area and large pore diameter 2 A nanofiber membrane. The method effectively solves the problem of porous SiO in the prior art 2 The fiber has the problems of high brittleness, easy fracture, small pore diameter, small pore volume and the like, and the obtained flexible porous SiO 2 The nanofiber membrane has the characteristics of good flexibility, high specific surface area, large aperture, large pore volume, controllable pore structure and the like, and has wide application prospects in the fields of national defense and military industry, environmental purification, adsorption separation, ion exchange and the like.)

1. Flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane is characterized by comprising the following steps of:

(1) sequentially adding a silicon source and a dispersing agent into a solvent, stirring and mixing for 30-90 min, adding a foaming agent, and continuously stirring for 15-40 min to obtain a precursor solution;

(2) preparing a precursor fiber film from the precursor solution by adopting an electrostatic spinning technology;

(3) raising the temperature of the precursor fiber film to 220-350 ℃ at a temperature raising speed of 0.5-2 ℃/min in an air atmosphere, then raising the temperature to 500-800 ℃ at a temperature raising speed of 5-10 ℃/min, and continuously calcining for 0-180 min to obtain the flexible porous SiO with high specific surface area and large aperture₂A nanofiber membrane.

2. The flexible porous SiO of claim 1 having both high surface area and large pore size₂The preparation method of the nanofiber membrane is characterized in that the silicon source in the step (1) is one or more of methyl orthosilicate, ethyl orthosilicate, methyltrichlorosilane, methyltriethoxysilane, 3-chloropropyltrichlorosilane, 3-chloropropyltriethoxysilane, (3-mercaptopropyl) triethoxysilane, gamma-aminopropylmethyldiethoxysilane, gamma-aminopropyltriethoxysilane and vinyltrimethoxysilane.

3. The flexible porous SiO of claim 1 having both high surface area and large pore size₂The preparation method of the nanofiber membrane is characterized in that the dispersant in the step (1) is dodecylSodium sulfate, sodium dodecyl benzene sulfonate, methylpentanol, triethylhexylphosphoric acid, sodium hexametaphosphate or sodium pyrophosphate or sodium tripolyphosphate.

4. The flexible porous SiO of claim 1 having both high surface area and large pore size₂The preparation method of the nanofiber membrane is characterized in that the foaming agent in the step (1) is one of calcium gluconate, calcium lactate, calcium phosphate, calcium carbide, calcium hydroxide, calcium chloride, calcium oxalate, calcium carbonate, protein, glucose, sucrose, azodicarbonamide and azodicarbonamide.

5. The flexible porous SiO of claim 1 having both high surface area and large pore size₂The preparation method of the nanofiber membrane is characterized in that the solvent in the step (1) is one or more of water, methanol, ethanol, ethylene glycol, glycerol, N-propanol, isopropanol, acetic acid, hydrochloric acid, nitric acid and N, N-dimethylformamide.

6. The flexible porous SiO of claim 1 having both high surface area and large pore size₂The preparation method of the nanofiber membrane is characterized in that the molar ratio of the silicon source to the dispersing agent in the step (1) is 1: 0.05-0.3; the ratio of the silicon source to the solvent is 10g: 5-50 mL; the molar ratio of the silicon source to the foaming agent is 1: 0.02-0.5; the dynamic viscosity of the precursor solution is 0.1-8 Pa · s, and the conductivity is 10-50 mS/m.

7. The flexible porous SiO of claim 1 having both high surface area and large pore size₂The preparation method of the nanofiber membrane is characterized in that the electrostatic spinning in the step (2) has the following technological parameters: and under the conditions that the spinning environment temperature is 10-40 ℃ and the relative humidity is 10-60%, filling the precursor solution at the flow rate of 0.1-5 mL/h, and connecting a spinning nozzle to a high-voltage power supply of 5-60 kV for spinning, wherein the distance between the receiving device and the spinning nozzle is 10-40 cm.

8. Flexible porous SiO prepared by the preparation method of any one of claims 1 to 7 and having both high specific surface area and large pore diameter₂Nanofiber membrane, characterized in that the flexible porous SiO₂The specific surface area of the nanofiber membrane is 200-650 m²Per g, the pore diameter is 0.1-15 nm, and the pore volume is 0.15-0.5 cm³/g。

9. Flexible porous SiO as claimed in claim 8₂Nanofiber membrane, characterized in that the flexible porous SiO₂The average fiber diameter of the nanofiber membrane is 20-450 nm, the relative standard deviation is 1-5%, and the flexible porous SiO₂The softness of the nanofiber membrane is 30-90 mN.

Technical Field

The invention belongs to the technical field of new materials, and particularly relates to flexible porous SiO with high specific surface area and large pore diameter₂A preparation method of a nanofiber membrane.

Background

Porous SiO₂The material has the advantages of high specific surface area, abundant pore channel structures, stable skeleton structure and the like, and shows excellent application performance in various fields. Porous SiO currently prepared₂The material generally takes monodisperse micro-nano particles as a main material, and the problems of easy falling, poor vibration resistance and the like exist when the material is used in an air medium due to the lack of firm mutual acting force among the particles, and the material is usually in a suspension state when the material is used in a liquid medium, so that the material has the problems of poor recyclability, easy secondary pollution and the like. For this purpose, researchers have used porous SiO with adhesives₂The particles are adhered to the surface of the matrix to improve the mechanical stability of the porous particle material, but a large amount of adhesive covers the surface of the particles, so that the pore channel structures on the surface and in the particles are seriously blocked, and the utilization rate of the pore structure is greatly reduced. Porous SiO₂Compared with the particle material, the fiber material has the advantages of large fiber length-diameter ratio, good fiber structure continuity, stable fiber aggregate structure and the like, and can effectively solve the bottleneck problem of the particle material in practical application. At present, porous SiO₂The preparation method of the fiber material mainly comprises a hard template method, a soft template method, a mechanical drawing method and an electrostatic spinning method, wherein the electrostatic spinning method has the advantages of simple equipment, low cost, wide range of spinnable raw materials, good structure adjustability, strong combination of multivariate technology and the like,has become the current continuous and stable preparation of porous SiO₂The most efficient method of fiber.

Chinese patent CN110485157A discloses a preparation method and application of a chitosan grafted mesoporous silica nanofiber membrane, wherein a surfactant Cetyl Trimethyl Ammonium Bromide (CTAB) is used as a pore-forming agent, polyvinyl alcohol (PVA) is used as a spinning auxiliary agent, and a mesoporous SiO is prepared by utilizing an electrostatic spinning technology and a high-temperature calcination method₂A nanofiber; korean patent KR102077419B1 discloses Titanium dioxide immobilized mesoporous silica nano-fiber and manufacturing method thereof, which uses surfactant polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) as pore-forming agent, polyvinylpyrrolidone (PVP) as spinning auxiliary agent, and utilizes electrostatic spinning technology and high-temperature calcination method to prepare porous SiO₂A nanofiber; chinese patent CN103316625B discloses a silicon oxide/titanium oxide composite mesoporous flexible non-woven fiber membrane, a preparation method and application thereof, wherein a surfactant (polyalkyl trimethyl ammonium bromide or polyalkyl trimethyl ammonium chloride) is used as a pore-forming agent, PVA (polyvinyl alcohol) or polyethylene oxide (PEO) is used as a spinning auxiliary agent, and an electrostatic spinning technology and a calcination method are utilized to prepare SiO₂/TiO₂Compounding a mesoporous flexible non-woven fiber membrane; chinese patent CN105648657B discloses aminated mesoporous silica fiber and its preparation method and application, in which polyoxyethylene-polyoxypropylene-polyoxyethylene (F127), P123 and CTAB are used as pore-forming agent, PVA, PVP and polyvinyl butyral (PVB) are used as spinning auxiliary agent, and the mesoporous SiO is prepared by electrostatic spinning technology and calcining method₂A nanofiber membrane. Nano Letters 6(2006)1042-1046, Journal of Nanoscience and Nanotechnology 8(2008)5147-5151, Journal of Colloid and Interface Science 341(2010)303-310, Advanced Functional Materials 21(2011)2356-2365, Nanoscale 3(2011)3601-3604, Chemical Communication 48(2012)9980-9982, Journal of Biomaterials Science-Polymer Edition 24(2013)1988-2005, Chemical Science 4(2013)4378-4382, Advanced Materials Research 731(2013)707-711, 20149-20149 (3) 6322-6324, material Research 108 and 2014108-2014 112-2014Preparation of porous SiO by electrospinning techniques is reported in materials 187(2014)53-62, RSC Advances 5(2015) 69631, Chemistry-A European Journal 21(2015)1-8, Colloids and Surfaces A570 (2019)1-10₂And (3) nano fibers.

The above-mentioned patent documents are in the preparation of porous SiO₂When the fiber is added with high molecular polymer as a spinning auxiliary agent, the content of inorganic components in a precursor solution is low, and the calcined SiO is caused₂The fiber yield is extremely low. Meanwhile, the above-mentioned patents all add surfactants as pore-forming agents, and micelles formed by self-assembly of surfactants are easily damaged by electric field interference during electrospinning, resulting in calcined SiO₂The pore diameter of the nano-fiber is small, and the pore structure is difficult to control effectively. In addition, the high molecular polymer in the precursor fiber is decomposed stably in the calcining process, which leads to serious volume shrinkage of the fiber in the calcining process, thus the mechanical property of the fiber membrane is deteriorated, and the flexible porous SiO is generally difficult to obtain₂A nanofiber membrane.

Chinese patent CN107354516A discloses an electrostatic spinning solution for porous silica fiber and a method for preparing porous silica fiber by electrostatic spinning, which uses carbon nanospheres, polymethyl methacrylate (PMMA) nanospheres or Polystyrene (PS) nanospheres as pore-forming agents, uses PVA as spinning aids, and utilizes electrostatic spinning technology and high-temperature calcination method to prepare porous SiO₂Fibers; chinese patent CN110813327A discloses a method for preparing a near-infrared responsive photocatalyst with porous silica fiber as a carrier and the photocatalyst, wherein Polyacrylonitrile (PAN) nanofiber is used as a template, the fiber is immersed in silica sol containing a surfactant, and then the porous carbon/SiO is prepared by high-temperature carbonization treatment₂Compounding nano fiber; applied Surface Science 313(2014)389-₂A nanofiber; journal of Nanomaterials 2017(2017)9621515 reports that carbon nanospheres are used as pore-forming agents, polyvinyl alcohol is used as a spinning aid, and a high-temperature calcination method is used for preparing the polyporeSiO pore₂A fiber. The above-mentioned patent documents are in the preparation of porous SiO₂When the fiber is added with a hard template as a pore-forming agent, although porous SiO with larger pore diameter is prepared₂Fibers, however, the addition of high molecular weight polymers as spinning aids to the precursor solution, results in calcined SiO₂The fiber yield is extremely low, and the volume of the precursor fiber is seriously shrunk in the calcining process, so that the fiber is easy to crack and has poor flexibility.

Chinese patent CN105603579A discloses a hollow molecular sieve fiber with high length-diameter ratio and a preparation method thereof, PVP is taken as a spinning auxiliary agent, and an electrostatic spinning technology and a hydrothermal reaction method are combined to prepare the molecular sieve fiber with a hollow structure; chemical Materials 19(2007)1231-1238 report that porous SiO is prepared by using a copolymer of 3-methacryloxypropyltrimethoxysilane and methyl methacrylate as a spinning aid and utilizing an electrostatic spinning technology and a calcination method₂A nanofiber membrane; journal of Composite Materials 46(2011)227-₂A nanofiber membrane; journal of Materials Chemistry A2 (2014)12442-12448 reports that mesoporous TiO is prepared by electrostatic spinning and high temperature calcination with PVP as a polymer template₂-SiO₂Composite fibers; ACS Applied Materials&Interfaces 9(2017)18966-18976 reports that PVB is used as a spinning auxiliary agent to prepare porous SiO by utilizing an electrostatic spinning technology and a high-temperature calcination method₂/SnO₂And (3) compounding the fibers. The patent uses high molecular polymer as spinning assistant and pore-forming agent, however, the introduction of large amount of polymer in the precursor solution will result in SiO after calcination₂The fiber yield is low. Meanwhile, the high molecular polymer is decomposed stably in the calcining process, so that the volume of the fiber is seriously shrunk in the calcining process, and the fiber is large in brittleness and easy to break.

Industrial&Engineering Chemistry Research 57(2018)11668-11674 reports that ethyl orthosilicate and 3-aminopropyltriethoxysilane are used as silicon sources, F127 and CTAB are used as porogens, a precursor fiber membrane is prepared by using a long-time aging method, and an extraction method is used for removing a surfactantObtaining porous SiO₂A nanofiber membrane; chemical Communication 20(2007)2043-2045 reports the preparation of mesoporous TiO by coaxial electrospinning₂/SiO₂Preparing porous SiO by long-time aging method and high-temperature calcining method by using a nanofiber membrane and P123 as a pore-foaming agent₂A nanofiber membrane; the Journal of Colloid and Interface Science 358(2011)547-₂A nanofiber membrane; porous SiO is prepared by aging method and calcining method by using tetraethoxysilane and 3-mercaptopropyltrimethoxysilane as silicon source and F127 as pore-forming agent in Colloid and Polymer Science 289(2011)1253-₂A nanofiber membrane; materials Letters 94(2013)100-103 report that porous SiO is prepared by using ethyl orthosilicate and 3-mercaptopropyltrimethoxysilane as silicon sources and F127 as a pore-forming agent and removing a template by an extraction method₂A nanofiber membrane. Although the above documents do not add a high molecular polymer during the preparation process, the preparation process requires a long time of aging, and the porous SiO obtained by the preparation process₂The fiber has small pore diameter and pore volume, and has the problems of poor fiber continuity and diameter uniformity, more single fiber defects and the like, so that the fiber is easy to crack and has poor mechanical properties.

Nanoscale 6(2014)12445-12449 reported the use of the immersion modification method in SiO₂Fiber surface loaded with SiO₂Nano particles to prepare SiO with porous structure₂And (3) nano fibers. However, SiO₂Nanoparticles and SiO₂The lack of interaction force among fibers leads to easy falling of particles and poor structural stability, and is difficult to meet the requirements of practical application.

Therefore, an SiO was developed₂High content, good flexibility, large specific surface area, large aperture, large pore volume, controllable pore structure, good structure stability and simple preparation process₂The nanofiber membrane and the preparation method thereof have very important significance.

Disclosure of Invention

Objects of the inventionProvides a flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane overcomes the problems that high-molecular polymers need to be added or the aging is carried out for a long time in the preparation process in the prior art, the preparation process is complex, the pore structure is difficult to regulate and control, the flexibility is poor, the fiber continuity is poor, the defects of single fibers are more and the like, and the prepared flexible porous SiO has good flexibility, large specific surface area, large pore diameter, large pore volume, controllable pore structure and high service stability₂A nanofiber membrane.

In order to achieve the purpose, the invention adopts the following technical scheme that the flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane comprises the following steps:

(1) sequentially adding a silicon source and a dispersing agent into a solvent, stirring and mixing for 30-90 min, adding a foaming agent, and continuously stirring for 15-40 min to obtain a precursor solution;

(2) preparing a precursor fiber film from the precursor solution by adopting an electrostatic spinning technology;

(3) raising the temperature of the precursor fiber film to 220-350 ℃ at a temperature raising speed of 0.5-2 ℃/min in an air atmosphere, then raising the temperature to 500-800 ℃ at a temperature raising speed of 5-10 ℃/min, and continuously calcining for 0-180 min to obtain the flexible porous SiO with high specific surface area and large aperture₂A nanofiber membrane.

As described above, the flexible porous SiO having both high specific surface area and large pore diameter₂In the preparation method of the nanofiber membrane, in the step (1), the silicon source is one or more of methyl orthosilicate, ethyl orthosilicate, methyltrichlorosilane, methyltriethoxysilane, 3-chloropropyltrichlorosilane, 3-chloropropyltriethoxysilane, (3-mercaptopropyl) triethoxysilane, gamma-aminopropylmethyldiethoxysilane, gamma-aminopropyltriethoxysilane and vinyltrimethoxysilane.

As described above, the flexible porous SiO having both high specific surface area and large pore diameter₂In the preparation method of the nanofiber membrane, the dispersing agent in the step (1) is sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, methylpentanol, triethylhexyl phosphoric acid, sodium hexametaphosphate or sodium pyrophosphate orOne kind of sodium tripolyphosphate.

As described above, the flexible porous SiO having both high specific surface area and large pore diameter₂In the preparation method of the nanofiber membrane, the foaming agent in the step (1) is one of calcium gluconate, calcium lactate, calcium phosphate, calcium carbide, calcium hydroxide, calcium chloride, calcium oxalate, calcium carbonate, protein, glucose, sucrose, azodicarbonamide or diethyl azodicarboxylate.

As described above, the flexible porous SiO having both high specific surface area and large pore diameter₂In the preparation method of the nanofiber membrane, the solvent in the step (1) is one or more of water, methanol, ethanol, glycol, glycerol, N-propanol, isopropanol, acetic acid, hydrochloric acid, nitric acid and N, N-dimethylformamide.

As described above, the flexible porous SiO having both high specific surface area and large pore diameter₂The preparation method of the nanofiber membrane comprises the following steps of (1) enabling the molar ratio of a silicon source to a dispersing agent to be 1: 0.05-0.3; the ratio of the silicon source to the solvent is 10g: 5-50 mL; the molar ratio of the silicon source to the foaming agent is 1: 0.02-0.5; the dynamic viscosity of the precursor solution is 0.1-8 Pa · s, and the conductivity is 10-50 mS/m.

As described above, the flexible porous SiO having both high specific surface area and large pore diameter₂The preparation method of the nanofiber membrane comprises the following process parameters of electrostatic spinning in the step (2): and under the conditions that the spinning environment temperature is 10-40 ℃ and the relative humidity is 10-60%, filling the precursor solution at the flow rate of 0.1-5 mL/h, and connecting a spinning nozzle to a high-voltage power supply of 5-60 kV for spinning, wherein the distance between the receiving device and the spinning nozzle is 10-40 cm.

The flexible porous SiO prepared by the preparation method of any one of the above methods and having both high specific surface area and large pore diameter₂A nanofiber membrane of the flexible porous SiO₂The specific surface area of the nanofiber membrane is 200-650 m²Per g, the pore diameter is 0.1-15 nm, and the pore volume is 0.15-0.5 cm³/g。

Flexible porous SiO as described above₂A nanofiber membrane of the flexible porous SiO₂The average fiber diameter of the nanofiber membrane is 20-450 nm, and the relative standard deviation isThe difference is 1-5%, and the flexible porous SiO₂The softness of the nanofiber membrane is 30-90 mN.

The diameter range of the fiber represents the thickness of the fiber, the diameter of the fiber is smaller, the flexibility of a single fiber is better, and the flexibility of the fiber film is improved; the relative standard deviation can be used to characterize the uniformity of the distribution of fiber diameters, with the smaller the relative deviation value, the better the fiber uniformity.

The invention principle is as follows:

according to the preparation method, a silicon source and a dispersing agent are sequentially dissolved in a solvent, the silicon source is hydrolyzed under the stirring action to form hydroxyl, silicon hydroxyl slowly condenses to form a short chain structure, a hydrophilic group on the dispersing agent is connected with the hydroxyl on a silicon-oxygen-silicon short chain through a covalent bond or a hydrogen bond, and an oleophylic group on the dispersing agent extends into the solution, so that the steric hindrance effect between Si-O-Si short chains is increased, and the local rapid condensation to form multi-branched spherical gel particles is avoided. And a precursor solution with a long-range chain molecular chain is formed, so that the viscosity of the precursor solution is increased, the spinnability is enhanced, and the precursor fiber has a uniform structure and good continuity. And then adding a foaming agent into the prepared precursor solution, and uniformly dispersing the foaming agent under the stirring action to obtain the precursor solution with better spinnability. During electrostatic spinning, the precursor solution is gradually stretched, thinned and solidified into fibers under the action of charge repulsion, and the foaming agent is uniformly dispersed on the cross section of the precursor fiber. And then, a precursor fiber film is slowly calcined at low temperature in air atmosphere in a two-stage heating mode, the foaming agent in the precursor fiber is promoted to be slowly decomposed to release gas, the gas is discharged out of the fiber to form a porous structure, the fiber is heated to high temperature to be continuously calcined, the unhydrolyzed organic groups on the chain type molecular chain are oxidized and cracked, and finally, the flexible porous SiO is obtained₂And (3) nano fibers. High molecular polymer is not required to be added in the preparation of precursor solution, so that the content of inorganic components in the precursor fiber is higher, and the unstable decomposition of a large amount of organic components in the complete framework structure and pore structure of single fiber is avoidedIs damaged, and finally the flexible porous SiO is obtained₂The nanofiber membrane has the characteristics of high specific surface area, adjustable pore diameter, large pore volume, adjustable pore channel structure and the like.

Has the advantages that:

(1) the flexible porous SiO prepared by the preparation method has high specific surface area and large pore diameter₂The nanofiber membrane has good flexibility, higher specific surface area, larger pore diameter and pore volume and controllable pore structure, and is beneficial to long-term stable service in practical application;

(2) the invention provides flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane is different from the traditional porous SiO₂The preparation method of the nanofiber material has the advantages that the precursor fiber does not need to be added with high-molecular polymers, the spinning solution has higher content of inorganic components, and porous SiO is obtained after calcination₂The nano-fiber has high yield, good fiber continuity, good mechanical property and good flexibility;

(3) the invention provides flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane has the advantages that the precursor solution does not need to undergo a complicated and time-consuming aging process, and the flexible porous SiO can be simply and efficiently prepared₂The nanofiber membrane has the advantages of simple preparation process, low cost and easy industrial production.

The specific implementation mode is as follows:

the invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Example 1

Flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane comprises the following specific steps:

(1) dissolving silicon source ethyl orthosilicate, 3-chloropropyl triethoxysilane and dispersant sodium dodecyl sulfate in turn in mixed solvent n-propanol/hydrochloric acid, stirring for 30min, adding a foaming agent calcium gluconate, and continuing stirring for 30min, wherein the molar ratio of the silicon source, the dispersant and the foaming agent in the solution is 1:0.16:0.18, the molar ratio of the ethyl orthosilicate to the 3-chloropropyl triethoxysilane is 2:1, the ratio of the silicon source to the solvent is 10g:40mL, the volume ratio of the n-propanol to the hydrochloric acid is 10:1, uniformly mixing to prepare a uniform stable precursor solution with dynamic viscosity of 4.7 Pa.s and conductivity of 19.2mS/m, and the precursor solution has a molecular chain with a long-range chain structure, and has the following structure:

(2) preparing the precursor solution into a precursor fiber film by adopting an electrostatic spinning technology, wherein the electrostatic spinning process parameters are as follows: the environment temperature is 26 ℃, the relative humidity is 43%, the perfusion speed is 2mL/h, the voltage is 47kV, and the distance between the receiving device and the spinning nozzle is 20 cm;

(3) calcining the precursor fiber film in an air atmosphere, wherein the calcining parameters are as follows: the temperature is gradually increased from room temperature to 280 ℃, the temperature rising speed is 0.5 ℃/min, then the temperature is increased to 700 ℃, the temperature rising speed is 10 ℃/min, and the temperature is kept for 45min at the highest calcining temperature, so that the flexible porous SiO is obtained₂A nanofiber membrane.

By property measurement, SiO₂The average diameter of the nanofibers was 240nm (measured according to national standard GB/T34520.2-2017 continuous silicon carbide fiber test method part 2: diameter of single fiber), the relative standard deviation of the diameters was 1.7%, and the flexible porous SiO₂The specific surface area of the nanofiber membrane is 360m²The pore diameter distribution is 1-2 nm and 2-10 nm, and the pore volume is 0.47cm³(ii)/g, a softness of 56mN (measured according to the national standard GB/T8942-2016 paper softness measurement).

Example 2

Flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane comprises the following specific steps:

(1) sequentially dissolving silicon source methyltrichlorosilane and dispersant sodium dodecyl benzene sulfonate into solvent water, stirring for 40min, adding foaming agent calcium lactate, and continuing stirring for 30min, wherein the molar ratio of the silicon source, the dispersant and the foaming agent in the solution is 1:0.24:0.16, the ratio of the silicon source to the solvent is 10g:45mL, uniformly mixing to prepare a uniform and stable precursor solution with dynamic viscosity of 4.1 Pa.s and conductivity of 17.6mS/m, and the precursor solution has a long-range chain-shaped molecular chain;

(2) preparing the precursor solution into a precursor fiber film by adopting an electrostatic spinning technology, wherein the electrostatic spinning process parameters are as follows: the environment temperature is 30 ℃, the relative humidity is 50%, the perfusion speed is 1.5mL/h, the voltage is 43kV, and the distance between the receiving device and the spinning nozzle is 21 cm;

(3) calcining the precursor fiber film in an air atmosphere, wherein the calcining parameters are as follows: the temperature is gradually increased from room temperature to 250 ℃, the temperature rising speed is 0.8 ℃/min, then the temperature is increased to 750 ℃, the temperature rising speed is 10 ℃/min, and the temperature is kept for 45min at the highest calcining temperature, so that the flexible porous SiO is obtained₂A nanofiber membrane.

SiO was measured in the same manner as in example 1₂The average diameter of the nano-fiber is 260nm, the relative standard deviation of the diameters is 1.9 percent, and the flexible porous SiO₂The specific surface area of the nanofiber membrane is 290m²The pore diameter is 2-12 nm, and the pore volume is 0.34cm³Softness was 44 mN/g.

Example 3

Flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane comprises the following specific steps:

(1) dissolving silicon source ethyl orthosilicate, 3-chloropropyl triethoxysilane and dispersant methylpentanol in turn in a mixed solvent of ethylene glycol/acetic acid, stirring for 50min, adding foaming agent calcium phosphate, and continuing stirring for 40min, wherein the molar ratio of the silicon source, the dispersant and the foaming agent in the solution is 1:0.25:0.15, the molar ratio of the ethyl orthosilicate to the 3-chloropropyl triethoxysilane is 2:1, the ratio of the silicon source to the solvent is 10g:48mL, the volume ratio of the ethylene glycol to the acetic acid is 6:1, uniformly mixing to prepare a uniform stable precursor solution with dynamic viscosity of 3.7 Pa.s and conductivity of 16.5mS/m, and the precursor solution has a molecular chain with a long-range chain structure;

(2) preparing the precursor solution into a precursor fiber film by adopting an electrostatic spinning technology, wherein the electrostatic spinning process parameters are as follows: the environment temperature is 27 ℃, the relative humidity is 52%, the perfusion speed is 4mL/h, the voltage is 48kV, and the distance between the receiving device and the spinning nozzle is 26 cm;

(3) calcining the precursor fiber film in an air atmosphere, wherein the calcining parameters are as follows: the temperature is gradually increased from room temperature to 260 ℃, the temperature rising speed is 0.8 ℃/min, then the temperature is increased to 800 ℃, the temperature rising speed is 10 ℃/min, and the temperature is kept for 30min at the highest calcining temperature, so that the flexible porous SiO is obtained₂A nanofiber membrane.

SiO was measured in the same manner as in example 1₂The average diameter of the nano-fiber is 280nm, the relative standard deviation of the diameters is 2.4 percent, and the flexible porous SiO₂The specific surface area of the nanofiber membrane was 370m²Per g, the pore diameter is 8-13 nm, and the pore volume is 0.39cm³Softness was 59 mN/g.

Example 4

Flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane comprises the following specific steps:

(1) sequentially dissolving a silicon source of methyl orthosilicate, 3-chloropropyl trichlorosilane and a dispersing agent of triethylhexyl phosphoric acid in a mixed solvent of methanol/nitric acid, stirring for 65min, adding a foaming agent of calcium hydroxide, and continuously stirring for 20min, wherein the molar ratio of the silicon source, the dispersing agent and the foaming agent in the solution is 1:0.19:0.34, the molar ratio of the methyl orthosilicate to the 3-chloropropyl trichlorosilane is 1:2, the ratio of the silicon source to the solvent is 10g:36mL, the volume ratio of the methanol to the nitric acid is 12:1, uniformly mixing to prepare a uniform stable precursor solution with dynamic viscosity of 2.5 Pa.s and conductivity of 14.8mS/m, and the precursor solution has a long-range chain-shaped molecular chain structure;

(2) preparing the precursor solution into a precursor fiber film by adopting an electrostatic spinning technology, wherein the electrostatic spinning process parameters are as follows: the environment temperature is 32 ℃, the relative humidity is 55%, the perfusion speed is 1.5mL/h, the voltage is 50kV, and the distance between the receiving device and the spinning nozzle is 24 cm;

(3) calcining the precursor fiber film in an air atmosphere, wherein the calcining parameters are as follows: the temperature is gradually increased from room temperature to 300 ℃, the temperature rising speed is 1 ℃/min, then the temperature rising speed is increased to 750 ℃, the temperature rising speed is 10 ℃/min, and the temperature is kept for 10min at the highest calcining temperature, so that the flexible porous SiO is obtained₂A nanofiber membrane.

SiO was measured in the same manner as in example 1₂The average diameter of the nano-fiber is 290nm, the relative standard deviation of the diameters is 2.4 percent, and the flexible porous SiO₂The specific surface area of the nanofiber membrane was 390m²The pore diameter is 1-4 nm and 5-9 nm, and the pore volume is 0.45cm³Per g, softness 53 mN.

Example 5

Flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane comprises the following specific steps:

(1) sequentially dissolving a silicon source 3-chloropropyltriethoxysilane and a dispersing agent sodium hexametaphosphate in a mixed solvent of glycerol/nitric acid, stirring for 50min, adding a foaming agent of calcium oxalate, and continuously stirring for 35min, wherein the molar ratio of the silicon source, the dispersing agent and the foaming agent in the solution is 1:0.15:0.25, the ratio of the silicon source to the solvent is 10g:35mL, the volume ratio of glycerol to nitric acid is 8:1, uniformly mixing to prepare a uniform stable precursor solution with the dynamic viscosity of 4.2 Pa.s and the conductivity of 18.8mS/m, and the precursor solution has a molecular chain with a long-range chain structure;

(2) preparing the precursor solution into a precursor fiber film by adopting an electrostatic spinning technology, wherein the electrostatic spinning process parameters are as follows: the environment temperature is 30 ℃, the relative humidity is 42%, the perfusion speed is 1mL/h, the voltage is 35kV, and the distance between the receiving device and the spinning nozzle is 24 cm;

(3) calcining the precursor fiber film in an air atmosphere, wherein the calcining parameters are as follows: the temperature is gradually increased from room temperature to 300 ℃, the temperature rising speed is 0.6 ℃/min, then the temperature is increased to 650 ℃, the temperature rising speed is 10 ℃/min, and the temperature is kept for 40min at the highest calcining temperature, so that the flexible porous SiO is obtained₂A nanofiber membrane.

SiO was measured in the same manner as in example 1₂The average diameter of the nano-fiber is 260nm, the relative standard deviation of the diameters is 1.5 percent, and the flexible porous SiO₂The specific surface area of the nanofiber membrane is 350m²Per g, the pore diameter is 5-14 nm, and the pore volume is 0.38cm³Per gram, softness is 46 mN.

Example 6

Flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane comprises the following specific steps:

(1) sequentially dissolving a silicon source (3-mercaptopropyl) triethoxysilane and a dispersing agent sodium pyrophosphate in a solvent N, N-dimethylformamide, stirring for 45min, adding a foaming agent protein, and continuously stirring for 40min, wherein the molar ratio of the silicon source, the dispersing agent and the foaming agent in the solution is 1:0.23:0.34, the ratio of the silicon source to the solvent is 10g:38mL, uniformly mixing to prepare a uniform and stable precursor solution with dynamic viscosity of 4.2Pa · s and conductivity of 16.9mS/m, and the precursor solution has a long-range chain-shaped molecular chain;

(2) preparing the precursor solution into a precursor fiber film by adopting an electrostatic spinning technology, wherein the electrostatic spinning process parameters are as follows: the environment temperature is 28 ℃, the relative humidity is 50%, the perfusion speed is 2mL/h, the voltage is 47kV, and the distance between the receiving device and the spinning nozzle is 25 cm;

(3) calcining the precursor fiber film in an air atmosphere, wherein the calcining parameters are as follows: the temperature is gradually increased from room temperature to 270 ℃, the temperature rising speed is 1 ℃/min, then the temperature rising speed is increased to 700 ℃, the temperature rising speed is 5 ℃/min, and the temperature is kept for 30min at the highest calcining temperature, so that the flexible porous SiO is obtained₂A nanofiber membrane.

SiO was measured in the same manner as in example 1₂The average diameter of the nano-fiber is 230nm, the relative standard deviation of the diameters is 1.8 percent, and the flexible porous SiO₂The specific surface area of the nanofiber membrane was 295m²Per g, the pore diameter is 6-12 nm, and the pore volume is 0.27cm³The softness was 39 mN/g.

Example 7

Have high specific surface concurrentlyFlexible porous SiO with large pore size₂The preparation method of the nanofiber membrane comprises the following specific steps:

(1) sequentially dissolving a silicon source gamma-aminopropyl methyl diethoxysilane and a dispersing agent sodium tripolyphosphate in a mixed solvent isopropanol/nitric acid, stirring for 90min, adding a foaming agent sucrose, and continuing stirring for 20min, wherein the molar ratio of the silicon source, the dispersing agent and the foaming agent in the solution is 1:0.18:0.32, the ratio of the silicon source to the solvent is 10g:28mL, the volume ratio of the isopropanol to the nitric acid is 12:1, uniformly mixing to prepare a uniform stable precursor solution with the dynamic viscosity of 3.8 Pa.s and the conductivity of 16.8mS/m, and the precursor solution has a long-range chain-shaped molecular chain structure;

(2) preparing the precursor solution into a precursor fiber film by adopting an electrostatic spinning technology, wherein the electrostatic spinning process parameters are as follows: the environment temperature is 22 ℃, the relative humidity is 29%, the perfusion speed is 6mL/h, the voltage is 56kV, and the distance between the receiving device and the spinning nozzle is 18 cm;

(3) calcining the precursor fiber film in an air atmosphere, wherein the calcining parameters are as follows: the temperature is gradually increased to 340 ℃ from room temperature, the temperature rising speed is 1 ℃/min, then the temperature rising speed is increased to 650 ℃, the temperature rising speed is 8 ℃/min, and the temperature is kept for 90min at the highest calcining temperature, so that the flexible porous SiO is obtained₂A nanofiber membrane.

SiO was measured in the same manner as in example 1₂The average diameter of the nano-fiber is 210nm, the relative standard deviation of the diameters is 1.7 percent, and the flexible porous SiO₂The specific surface area of the nanofiber membrane is 330m²Per g, the pore diameter is 0.6-10 nm, and the pore volume is 0.34cm³Per g, softness 50 mN.

Example 8

Flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane comprises the following specific steps:

(1) dissolving a silicon source gamma-aminopropyltriethoxysilane and a dispersing agent sodium dodecyl sulfate in a mixed solvent ethanol/acetic acid in sequence, stirring for 60min, adding a foaming agent diethyl azodicarboxylate, and continuing stirring for 25min, wherein the molar ratio of the silicon source, the dispersing agent and the foaming agent in the solution is 1:0.17:0.34, the ratio of the silicon source to the solvent is 10g:40mL, the volume ratio of ethanol to acetic acid is 1:1, uniformly mixing to prepare a uniform and stable precursor solution with the dynamic viscosity of 2.9 Pa.s and the conductivity of 18.5mS/m, and the precursor solution has a long-range chain-shaped molecular chain structure;

(2) preparing the precursor solution into a precursor fiber film by adopting an electrostatic spinning technology, wherein the electrostatic spinning process parameters are as follows: the environment temperature is 29 ℃, the relative humidity is 18%, the perfusion speed is 5.5mL/h, the voltage is 53kV, and the distance between the receiving device and the spinning nozzle is 22 cm;

(3) calcining the precursor fiber film in an air atmosphere, wherein the calcining parameters are as follows: the temperature is gradually increased from room temperature to 290 ℃, the temperature rising speed is 0.9 ℃/min, then the temperature is increased to 650 ℃, the temperature rising speed is 10 ℃/min, and the temperature is kept for 15min at the highest calcining temperature, so that the flexible porous SiO is obtained₂A nanofiber membrane.

SiO was measured in the same manner as in example 1₂The average diameter of the nano-fiber is 270nm, the relative standard deviation of the diameters is 1.9 percent, and the flexible porous SiO₂The specific surface area of the nanofiber membrane is 360m²Per g, the pore diameter is 0.3-8 nm, and the pore volume is 0.37cm³Per g, softness 53 mN.

Example 9

Flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane comprises the following specific steps:

(1) sequentially dissolving silicon source vinyl trimethoxy silane and dispersing agent triethylhexyl phosphoric acid in a solvent N, N-dimethylformamide, stirring for 55min, adding a foaming agent glucose, and continuously stirring for 25min, wherein the molar ratio of the silicon source to the dispersing agent to the foaming agent in the solution is 1:0.24:0.36, the ratio of the silicon source to the solvent is 10g:36mL, uniformly mixing to prepare a uniform stable precursor solution with dynamic viscosity of 4.9 Pa.s and conductivity of 25.3mS/m, wherein the precursor solution has a long-range chain-shaped molecular chain;

(2) preparing the precursor solution into a precursor fiber film by adopting an electrostatic spinning technology, wherein the electrostatic spinning process parameters are as follows: the environment temperature is 25 ℃, the relative humidity is 40%, the perfusion speed is 3mL/h, the voltage is 36kV, and the distance between the receiving device and the spinning nozzle is 25 cm;

(3) calcining the precursor fiber film in an air atmosphere, wherein the calcining parameters are as follows: the temperature is gradually increased from room temperature to 350 ℃, the temperature rising speed is 0.6 ℃/min, then the temperature is increased to 700 ℃, the temperature rising speed is 10 ℃/min, and the temperature is kept for 20min at the highest calcining temperature, so that the flexible porous SiO is obtained₂A nanofiber membrane.

SiO was measured in the same manner as in example 1₂The average diameter of the nano-fiber is 340nm, the relative standard deviation of the diameters is 1.9 percent, and the flexible porous SiO₂The specific surface area of the nanofiber membrane is 350m²Per g, the pore diameter is 2-15 nm, and the pore volume is 0.38cm³The softness was 63 mN/g.

Example 10

Flexible porous SiO with high specific surface area and large aperture₂The preparation method of the nanofiber membrane comprises the following specific steps:

(1) sequentially dissolving a silicon source gamma-aminopropyl methyl diethoxy silane, methyl trichlorosilane and a dispersing agent sodium dodecyl benzene sulfonate into a mixed solvent ethylene glycol/nitric acid, stirring for 40min, adding a foaming agent azodicarbonamide, and continuously stirring for 15min, wherein the molar ratio of the silicon source, the dispersing agent and the foaming agent in the solution is 1:0.14:0.14, the molar ratio of the gamma-aminopropyl methyl diethoxy silane to the methyl trichlorosilane is 2:1, the ratio of the silicon source to the solvent is 10g:28mL, the volume ratio of the ethylene glycol to the nitric acid is 15:1, uniformly mixing to prepare a uniform and stable precursor solution with dynamic viscosity of 5.9Pa s and conductivity of 21.8mS/m, and the precursor solution has a long-range chain-shaped molecular chain structure;

(2) preparing the precursor solution into a precursor fiber film by adopting an electrostatic spinning technology, wherein the electrostatic spinning process parameters are as follows: the environment temperature is 23 ℃, the relative humidity is 41%, the perfusion speed is 1mL/h, the voltage is 32kV, and the distance between the receiving device and the spinning nozzle is 26 cm;

(3) calcining the precursor fiber film in an air atmosphere, wherein the calcining parameters are as follows: the temperature is gradually increased from room temperature to 320 ℃, the temperature increasing speed is 1.2 ℃/min, then the temperature is increased to 800 ℃, the temperature increasing speed is 8 ℃/min, and the temperature is increased at the highest calcining temperatureKeeping for 10min to obtain flexible porous SiO₂A nanofiber membrane.

SiO was measured in the same manner as in example 1₂The average diameter of the nano-fiber is 360nm, the relative standard deviation of the diameters is 2.4 percent, and the flexible porous SiO₂The specific surface area of the nanofiber membrane is 530m²Per g, the pore diameter is 0.3-11 nm, and the pore volume is 0.45cm³The softness was 77 mN/g.