Controllable synthesis, chain extension and spinning method of linear inorganic molecular chain

Abstract

This invention relates to a controllable synthesis, chain extension, and spinning method for linear inorganic molecular chains. The preparation method includes: constructing a stable linear pre-coordinated framework by synergistic action of a linear rigid bidentate linker and a flexible bidentate stabilizer, coordinating with a metal alkoxide monomer. Subsequently, under controllable conditions, this framework is converted into a low-polymerization-degree linear inorganic molecular chain through a hydrolysis-condensation reaction. Next, the molecular chain is linearly extended using a bifunctional chain extender centered on a metal element, and high-polymerization-degree linear inorganic long chains are obtained by end-capping. Finally, the obtained long chains are blended with molecular gears and a mixed solvent to prepare a homogeneous and stable spinning solution, which is then spun to obtain precursor nanofibers. Compared with existing technologies, this invention overcomes the problems of easy gelation and pore defects caused by template decomposition in traditional sol-gel methods, providing a reliable new approach for the preparation of high-performance ceramic nanofibers.

Description

Technical Field

[0001] This invention relates to the field of linear inorganic molecular chain solution preparation technology, and in particular to a method for the controllable synthesis, chain extension and spinning of linear inorganic molecular chains. Background Technology

[0002] Ceramic nanofiber materials possess characteristics such as high temperature resistance, corrosion resistance, high porosity, large specific surface area, light weight, and strong small size effect. They play a core supporting role in key fields such as aerospace, electronic information, clean energy, and environmental governance. They not only have extremely high practical application value, but also create significant social and economic benefits.

[0003] When preparing ceramic nanofibers using electrospinning technology, in addition to inorganic sols, spinning solutions require the addition of spinning aids such as organic polymer templates. For example, patent applications CN202510071489.X, CN202410538707.1, and CN202311575862.2 all require polymer templates to prepare continuous nanofibers. During the ceramicization of precursor fibers, the polymer template undergoes thermal decomposition, resulting in numerous pore defects within the fibers, leading to insufficient flexibility and poor mechanical properties. To address these issues, researchers have developed inorganic sol systems that allow direct spinning without polymer templates. For instance, patent application ZL202311761247.0 describes a spinning solution that can be directly electrospinned by mixing and stirring alkoxides, organic solvents, water, and a primary inorganic acid to obtain an inorganic sol, followed by secondary acidification and concentration. However, this simple mixing of all raw materials makes it difficult to precisely control the reaction direction, easily causing branching of linear inorganic molecular chains. Patent applications ZL202111391692.3, ZL202111391725.4, and ZL202111376361.2, among others, reduce branching to some extent by coordinating and protecting metal alkoxide monomers. However, these methods still cannot achieve precise control over the degree of polymerization of inorganic sols, and some active groups remain in the system, making the sol prone to solidification. Therefore, these sol preparation methods still cannot meet the application requirements of industrial production.

[0004] Therefore, there is an urgent need to develop linear inorganic molecular chain spinning solutions that can be directly electrospun, stably produce nano-sized fibers, do not gel, and have good storage stability, and to establish new methods for the controllable synthesis, chain extension, and spinning of linear inorganic molecular chains. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing a method for the controllable synthesis, chain extension and spinning of linear inorganic molecular chains, namely a method for preparing ceramic nanofiber precursors based on linear inorganic molecular chain synthesis technology. This method overcomes the problems of easy gelation and pore defects caused by template decomposition in the traditional sol-gel method, and provides a reliable new approach for the preparation of high-performance ceramic nanofibers.

[0006] The objective of this invention can be achieved through the following technical solutions: This invention provides a method for the controllable synthesis, chain extension, and spinning of linear inorganic molecular chains, comprising the following steps: S1. A linear, rigid bidentate linker is used to link metal alkoxide monomers to form a linear linking structure. Then, a flexible, bidentate stabilizer is added to replace the remaining active groups on the metal alkoxide monomers to form a stable linear pre-coordinated framework. S2. The linear connection structure of the linear pre-coordinated framework is transformed into a metal-oxygen-metal structure through hydrolysis-condensation reaction to obtain a low-polymerization degree linear inorganic molecular chain. S3. Use a metal-centered bifunctional chain extender to linearly extend low-polymerization-degree linear inorganic molecular chains, and then use an end-capping agent to terminate the chain extension reaction to obtain high-polymerization-degree linear inorganic long chains. S4. Add molecular gears and mixed solvent to the solution of the linear inorganic long chain to prepare a linear inorganic long chain spinning solution, and then prepare precursor nanofibers by spinning.

[0007] Furthermore, S1 specifically includes the following processes: A nonpolar solvent is added to a linear, rigid bidentate linker for dilution. The diluted solution is then slowly added dropwise to a metal alkoxide solution under an inert atmosphere, low temperature, and high-speed stirring. The linker acts as an intermediate to intersect the metal alkoxide monomers, forming a linear linkage structure. A flexible, bidentate stabilizer is then added to replace the remaining active groups on the metal alkoxide monomers, forming a stable linear pre-coordinated framework.

[0008] Furthermore, in S1, the metal alkoxide monomer contains at least three hydrolyzable alkoxy groups; The metal alkoxide is selected from one or more combinations of titanium source, zirconium source, aluminum source, gallium source, niobium source, hafnium source, tantalum source, and tin source; The titanium source is selected from one or more combinations of titanium tetramethanol, titanium tetraethanol, titanium n-propoxide, titanium isopropoxide, titanium n-butoxide, titanium isobutoxide, titanium tert-butoxide, titanium tetrapentoxide, and titanium isooctoxide. The zirconium source is selected from one or more combinations of zirconium tetramethanol, zirconium tetraethanol, zirconium n-propoxide, zirconium isopropoxide, zirconium n-butoxide, zirconium isobutoxide, zirconium tert-butoxide, and zirconium tetrapentoxide. The aluminum source is selected from one or more combinations of aluminum trimethoxy, aluminum triethanolamine, aluminum tri-n-propoxy, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, and aluminum tert-butoxide. The gallium source is selected from one or more combinations of gallium isopropoxide and gallium tert-butoxide; The niobium source is selected from one or more combinations of niobium isopropoxide and niobium n-butoxide; The hafnium source is selected from one or more combinations of tetramethanol hafnium, tetraethanol hafnium, n-propanol hafnium, isopropanol hafnium, n-butanol hafnium, isobutanol hafnium, tert-butanol hafnium, and tetrapentanol hafnium; The tantalum source is selected from one or more combinations of tantalum isopropoxide and tantalum n-butoxide; The tin source is selected from one or more combinations of tin tetramethanol, tin tetraethanol, tin n-propoxide, tin isopropoxide, tin n-butoxide, tin isobutoxide, tin tert-butoxide, and tin tetrapentoxide. The linear, rigid bidentate linker has a conjugated aromatic ring or a rigid heterocyclic skeleton, with two coordinating atoms located at para or linearly symmetric sites, which can coordinate with different metal alkoxide monomers respectively, thus linearly linking the metal alkoxide monomers. The linear, rigid bidental connector is selected from one or more combinations of p-phenylenediamine, 1,4-naphthylenediamine, terephthalic acid, or 1,4-diphenylhydrazine. The flexible, bidentate stabilizer forms a coordination bond with the metal center of the metal alkoxide monomer with high bond energy and high kinetic dissociation difficulty. In addition, the ligand itself does not contain a conjugated aromatic ring or a rigid heterocyclic skeleton, and has excellent chemical stability, forming a stable chemical structure with the metal alkoxide. The flexible, bidentate stabilizer is selected from one or more combinations of ethylenediamine, tetramethylethylenediamine, and acetylacetone.

[0009] Further, in S1, the nonpolar solvent is one or a combination of toluene, p-xylene, carbon tetrachloride, and dichloromethane; The dilution process involves diluting a linear, rigid bidental connector with a nonpolar solvent at a volume ratio of 1:2 to 1:10. The inert atmosphere is one or more combinations of nitrogen, helium, neon, argon, krypton, and xenon atmospheres; The low temperature condition is -20~0℃; The slow dripping rate is 0.01~0.2wt% / s of the metal alkoxide monomer mass; The high-speed stirring conditions are 300~1000 rpm.

[0010] Furthermore, S2 specifically includes the following processes: The pre-coordinated framework solution prepared by S1 was adjusted to acidity. Then, thermosensitive hydrogel microspheres were added. Water in the microspheres was released by low-temperature heating. Under high-temperature heating and negative pressure suction, the linear connection structure of the pre-coordinated framework was transformed into a metal-oxygen-metal structure through hydrolysis-condensation reaction, and a low degree of polymerization linear inorganic molecular chain was initially obtained. The temperature-sensitive hydrogel microspheres are selected from one or more combinations of poly(N-isopropylacrylamide) hydrogel microspheres, poly(N-isopropylacrylamide-acrylic acid) hydrogel microspheres, poly(N-isopropylacrylamide-hydroxyethyl methacrylate) hydrogel microspheres, and carboxymethyl chitosan hydrogel microspheres. The total water content of the thermosensitive hydrogel microspheres is 5-20 wt% of the metal alkoxide monomer, preferably 10-12 wt%. The low-temperature heating temperature is 5~50℃.

[0011] Furthermore, in S2, the acidity is achieved by adjusting the pH of the solution to 1~5, and the method of adjusting the acidity is by adding an inorganic acid, which is selected from one or more combinations of hydrochloric acid, nitric acid, and phosphoric acid; the high temperature heating conditions are 60~150℃, the negative pressure suction pressure is -0.1~0MPa, and the reaction time is 0.1~8h; The degree of polymerization of the low-polymerization linear inorganic molecular chain is 10~50; Furthermore, S3 specifically includes the following processes: A bifunctional chain extender centered on a metal element is added to the solution of the low-polymerization-degree linear inorganic molecular chain obtained in S2 to extend the low-polymerization-degree linear inorganic molecular chain. Then, the chain extension reaction is terminated by a capping agent to obtain a high-polymerization-degree linear inorganic long chain with controllable polymerization degree.

[0012] Further, in S3, the metal-centered bifunctional chain extender is selected from one or more of diisopropoxydiacetylacetonate titanium, bis(ethyl acetoacetate)titanate diisopropyl ester, bis(diethylcitrate)dipropoxide zirconium, (ethyl acetoacetate)diisopropoxyaluminate, dichlorodicyclopentadiene titanium, dichlorodicyclopentadiene zirconium, dichlorodicyclopentadiene hafnium, dichlorodicyclopentadiene molybdenum, dichlorodicyclopentadiene vanadium, and dichlorodicyclopentadiene niobium; the amount of the metal-centered bifunctional chain extender added is 1 to 10 wt% of the mass of the metal alkoxide monomer.

[0013] The capping agent is selected from one or more of common chemical capping agents, visible light responsive capping agents, and ultraviolet light responsive capping agents; the amount of capping agent added is 0.1~10wt% of the mass of the metal alkoxide monomer, preferably 7~10wt%.

[0014] The common chemical end-capping agent is selected from one or more of methyl isocyanate and phenyl isocyanate; The visible light end-capping agent is selected from one or more of 2-diazo-1-naphthol-5-sulfonyl chloride, ethyl diazonyl chloride, and 4-azido-2,3,5,6-tetrafluorobenzoic acid; The ultraviolet light responsive end-capping agent is selected from one or more of 4-azidobenzoic acid, 3-azidopropyltrimethoxysilane, and 1,3-dioxopentanepropyltrimethoxysilane; The linear inorganic long chain has a degree of polymerization of 200 to 5000 and a molecular weight of 1 to 1 million.

[0015] Furthermore, S4 specifically includes the following processes: Molecular gears and a mixed solvent are added to a solution of linear inorganic long chains to regulate solution parameters affecting fiber formation, such as solid content, viscosity, conductivity, surface tension, and specific viscosity, thereby preparing a linear inorganic long-chain spinning solution. Precursor nanofibers are then prepared by spinning. The amount of molecular gears added is 0.1–15 wt% of the mass of the linear inorganic long chains, preferably 2–15 wt%, and the amount of the mixed solvent is 25–100 wt% of the mass of the linear inorganic long chains, preferably 25–30 wt%.

[0016] Furthermore, the molecular gear is selected from one or more of inositol triphosphate, cyclohexanehexol, and cyclohexanehexol phosphate; The mixed solvent is a solvent prepared by mixing alcohols, ethers, and amides, wherein the alcohol accounts for 70-90 wt%, preferably 70-80 wt%, the ether accounts for 5-20 wt%, preferably 15-20 wt%, and the amide accounts for 5-10 wt%. The alcohol solvent is selected from one or more combinations of methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, ethylene glycol, butanediol, hexanediol, and glycerol; The ether solvent is selected from one or more combinations of diethyl ether, diphenyl ether, tetrahydrofuran, and ethylene glycol dimethyl ether; The amide solvent is selected from one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; The linear inorganic long-chain spinning solution has a solid content of 10-50 wt%, a viscosity of 10-500 mPa·s, an electrical conductivity of 1-100 μS / cm, a surface tension of 30-120 mN / m, and a specific viscosity of 0.3-0.9. The stable storage time is greater than 60 days, and it can be directly used for spinning; The precursor nanofibers have a diameter of 200~1000nm.

[0017] The mechanism of this invention is as follows (see Figure 1 and Figure 3): The metal alkoxide monomers used in linear inorganic long-chain spinning solutions contain three or more hydrolyzable alkoxy groups. These metal alkoxides can undergo nucleophilic hydrolysis and condensation polymerization to obtain inorganic molecular chains. Although alkoxides are soluble in alcohol solvents, the hydroxyl groups of the alcohol solvent readily adsorb onto the metal atoms of the metal alkoxide, causing a shielding effect that isolates the metal atoms from the external environment, making it difficult for the metal alkoxide monomer to undergo substitution or coordination reactions. Therefore, this invention uses a non-polar solvent to dilute the linker to avoid the effects of the shielding effect.

[0018] Linear, rigid bidentate linkers possess conjugated aromatic rings or rigid heterocyclic skeletons, with two coordinating atoms located at para or linearly symmetric sites, allowing them to undergo substitution and coordination with different metal alkoxide monomers. When a metal alkoxide monomer reacts with a linear, rigid bidentate linker, after substituting one alkoxy group, due to steric hindrance, the metal alkoxide monomer and the other bidentate linker will undergo para substitution. Therefore, metal alkoxide monomers can be linearly linked with linear, rigid bidentate linkers to form linearly connected structures. Furthermore, flexible, bidentate protectants form coordination bonds with the metal center of the metal alkoxide with higher bond energies, stronger coordination substitution capabilities, and greater kinetic dissociation difficulty. The ligands themselves also exhibit excellent chemical stability, enabling them to undergo substitution reactions with metal alkoxides. By combining linear, rigid bidentate linkers with flexible, bidentate stabilizers, linear pre-coordinated frameworks can be prepared.

[0019] After forming a linear pre-coordinated framework, the solution is further acidified and the pH is controlled to reduce the H+ content in the solution. + Only the linker is protonated, while the stabilizer is not. This way, during hydrolysis, water molecules will only undergo nucleophilic reactions with the linear, rigid bidentate linker. The linear linking structure in the linear pre-coordinated framework can be transformed into a metal-oxygen-metal structure through a hydrolysis-condensation chemical reaction.

[0020] After the polycondensation reaction reaches a certain extent, even with methods such as heating and removing byproducts under negative pressure, the reaction will slow down. Therefore, this invention adds a bifunctional chain extender centered on a metal element. The chain extender's active groups, such as alkoxy groups, react with the hydroxyl groups on the metal-oxygen backbone to further linearly grow the inorganic molecular chain, forming a high-polymerization-degree linear inorganic long chain. Then, a capping agent is added to terminate the chain extension reaction. The capped linear inorganic long chain can be stored for a long time.

[0021] By adding molecular gears and mixed solvents to regulate the solution parameters affecting fiber formation, a linear inorganic long-chain spinning solution was prepared. The hydroxyl groups of the molecular gears interact with the oxygen atoms in the linear inorganic long chains through hydrogen bonding. Under the action of an electric field, the molecular gears can rotate, driving the linear inorganic long chains to shift in orientation, thereby achieving continuous stretching and refinement of the spinning jet and preparing precursor nanofibers.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention, through the synergistic effect of a linear rigid bidentate linker and a flexible bidentate stabilizer, can precisely construct a stable linear molecular framework in advance, effectively suppressing the branching side reactions commonly encountered during the hydrolysis-condensation process of metal alkoxides, thus laying a structural foundation for the linear and controllable growth of inorganic molecular chains. With the coordination of chain extension and end-capping steps, the degree of polymerization (molecular weight) of inorganic molecular chains can be precisely controlled, thereby obtaining high-molecular-weight linear inorganic long chains with well-defined structures. Based on this, by introducing molecular gears and optimizing the solvent system, the prepared spinning solution exhibits excellent solution properties and storage stability exceeding 60 days. It can be directly used for spinning without the addition of a polymer template, ultimately successfully preparing precursor nanofibers with uniform diameters (200-1000 nm). This overcomes the problems of easy gelation and pore defects caused by template decomposition in traditional sol-gel methods, providing a reliable new approach for the preparation of high-performance ceramic nanofibers.

[0023] 2) In this invention, temperature-sensitive hydrogel microspheres are added to the reaction system, and then the temperature is controlled to achieve uniform and controllable release of water. While ensuring the release rate, water molecules are uniformly dispersed, thereby avoiding the sol-gel phenomenon caused by high local water molecule concentration and shortening the hydrolysis reaction cycle.

[0024] 3) By adding a bifunctional chain extender centered on a metal element, the present invention can utilize the active groups on the chain extender to further linearly connect inorganic molecular chains and increase the degree of polymerization; further, the chain extension reaction can be terminated by a capping agent to prepare a high degree of polymerization linear inorganic long chain. Attached Figure Description

[0025] Figure 1 A schematic diagram of the synthesis of linear inorganic long chains from metal alkoxide monomers; Figure 2 This is a gel chromatography chromatogram of the linear inorganic long chains obtained in Example 1; Figure 3 This is a schematic diagram of linear inorganic long-chain solution spinning for doped molecular gears. Detailed Implementation

[0026] Overall, this invention provides a method for the controllable synthesis, chain extension, and spinning of linear inorganic molecular chains, comprising the following steps: S1. A non-polar solvent is added to a linear, rigid bidentate linker for dilution. Then, the diluted solution is slowly added dropwise to a metal alkoxide solution under an inert atmosphere, low temperature and high speed stirring. The linker acts as an intermediate to connect the metal alkoxide monomers at intervals to form a linear linking structure. Then, a flexible, bidentate stabilizer is added to replace the remaining active groups on the metal alkoxide monomers to form a stable linear pre-coordinated framework. S2. The pre-coordinated framework solution prepared in S1 is adjusted to acidity. Then, temperature-sensitive hydrogel microspheres are added. Water in the microspheres is released by low-temperature heating. Under high-temperature heating and negative pressure suction, the linear connection structure of the pre-coordinated framework is transformed into a metal-oxygen-metal structure through hydrolysis-condensation reaction, and a low degree of polymerization linear inorganic molecular chain is initially obtained. S3. Further, a bifunctional chain extender centered on a metal element is added to extend the low degree of polymerization linear inorganic molecular chain. Then, the chain extension reaction is terminated by a capping agent to obtain a high degree of polymerization linear inorganic long chain with controllable degree of polymerization. S4. Molecular gears and mixed solvents are added to the linear inorganic long-chain solution to regulate the solution parameters that affect fiber formation, such as solid content, viscosity, conductivity, surface tension and specific viscosity, in order to prepare a linear inorganic long-chain spinning solution, and then precursor nanofibers are prepared by spinning.

[0027] In one embodiment of the present invention, in step S1, the metal alkoxide monomer comprises three or more hydrolyzable alkoxy groups; the metal alkoxide is selected from one or more combinations of titanium source, zirconium source, aluminum source, gallium source, niobium source, hafnium source, tantalum source, or tin source; the titanium source is selected from one or more combinations of titanium tetraethanol, titanium tetraethanol, titanium n-propoxide, titanium isopropoxide, titanium n-butoxide, titanium isobutoxide, titanium tert-butoxide, titanium tetrapentoxide, or titanium isooctanol; the zirconium source is selected from zirconium tetraethanol, zirconium tetraethanol, zirconium n-propoxide, or zirconium isopropoxide. The aluminum source is selected from one or more combinations of zirconium n-butoxide, zirconium isobutoxide, zirconium tert-butoxide, or zirconium tetrapentoxide; the gallium source is selected from one or more combinations of aluminum trimethoxy, aluminum triethanoloxide, aluminum tri-n-propoxy, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, or aluminum tert-butoxide; the gallium source is selected from one or more combinations of gallium isopropoxide and gallium tert-butoxide; the niobium source is selected from one or more combinations of niobium isopropoxide and niobium n-butoxide; the hafnium source is selected from hafnium tetramethanol, hafnium tetraethanol, hafnium n-propoxide, hafnium isopropoxide, hafnium n-butoxide, hafnium isobutoxide, hafnium tert-butoxide, or zirconium tetrapentoxide. The tantalum source is selected from one or more combinations of hafnium alkoxide or tetrapentoxide; the tantalum source is selected from one or more combinations of isopropoxide tantalum and n-butoxide tantalum; the tin source is selected from one or more combinations of tetramethyltin, tetraethanoltin, n-propoxide tin, isopropoxide tin, n-butoxide tin, isobutoxide tin, tert-butoxide tin, or tetrapentoxide tin; the linear, rigid bidentate linker has a conjugated aromatic ring or a rigid heterocyclic skeleton, with two coordinating atoms located at para or linearly symmetric sites, which can coordinate with different metal alkoxide monomers respectively, so as to linearly bind the metal alkoxide monomers. The linear, rigid bidentate linker is selected from one or more of p-phenylenediamine, 1,4-naphthylenediamine, terephthalic acid, or 1,4-diphenylacetone; the flexible, bidentate stabilizer forms a high-energy coordination bond with the metal center of the metal alkoxide monomer, which is difficult to kinetically dissociate, and the ligand itself does not contain a conjugated aromatic ring or a rigid heterocyclic skeleton, exhibiting excellent chemical stability and forming a stable chemical structure with the metal alkoxide; the flexible, bidentate stabilizer is selected from one or more of ethylenediamine, tetramethylethylenediamine, and acetylacetone.

[0028] In one embodiment of the present invention, in step S1, the nonpolar solvent is one or more of toluene, p-xylene, carbon tetrachloride or dichloromethane; the dilution is to dilute the linear, rigid bitenteric linker with the nonpolar solvent at a volume ratio of 1:2 to 1:10.

[0029] In one embodiment of the present invention, in step S1, the conditions for carrying out the coordination reaction are as follows: the inert atmosphere is one or more combinations of nitrogen, helium, neon, argon, krypton or xenon; the low temperature condition is -20~0℃; the slow dropping rate is 0.01~0.2wt% / s of the mass of the metal alkoxide monomer; and the high-speed stirring condition is 300~1000rpm.

[0030] In one embodiment of the present invention, in step S2, the temperature-sensitive hydrogel microspheres are selected from one or more combinations of poly(N-isopropylacrylamide) hydrogel microspheres, poly(N-isopropylacrylamide-acrylic acid) hydrogel microspheres, poly(N-isopropylacrylamide-hydroxyethyl methacrylate) hydrogel microspheres, and carboxymethyl chitosan microspheres, and the total water content of the temperature-sensitive hydrogel microspheres is 5-20 wt% of the mass of the metal alkoxide monomer; the low-temperature heating temperature is 5-50°C.

[0031] In one embodiment of the present invention, in step S2, the further preferred reaction conditions are as follows: the acidity is such that the solution pH is 1~5, and the acidity is adjusted by adding an inorganic acid, which is selected from one or more combinations of hydrochloric acid, nitric acid, and phosphoric acid; the high temperature heating conditions are 60~150℃, the negative pressure suction pressure is -0.1~0MPa, and the reaction time is 0.1~8h; the degree of polymerization of the low degree of polymerization linear inorganic molecular chain is 10~50.

[0032] In one embodiment of the present invention, in step S3, the amount of the metal element-centered bifunctional chain extender added is 1-10 wt% of the mass of the metal alkoxide monomer, and the metal element-centered bifunctional chain extender is one or more selected from diisopropoxydiacetylacetonitrile, diisopropyl bis(ethyl acetoacetate)titanate, dizirconia di(diethylcitrate)propoxide, diisopropoxyaluminate (ethyl acetoacetate)diisopropoxyaluminate, titanium dichlorophenoxy, zirconium dichlorophenoxy, hafnium dichlorophenoxy, molybdenum dichlorophenoxy, vanadium dichlorophenoxy, and niobium dichlorophenoxy; the amount of the end-capping agent added is 0.1-10 wt% of the mass of the metal alkoxide monomer, and the end-capping agent is selected from common chemical end-capping agents. The product comprises one or more of visible light responsive end-capping agents and ultraviolet light responsive end-capping agents; the common chemical end-capping agent is selected from one or more combinations of methyl isocyanate and phenyl isocyanate; the visible light end-capping agent is selected from one or more combinations of 2-diazo-1-naphthol-5-sulfonyl chloride, ethyl diazonate, and 4-azido-2,3,5,6-tetrafluorobenzoic acid; the ultraviolet light responsive end-capping agent is selected from one or more combinations of 4-azidobenzoic acid, 3-azidopropyltrimethoxysilane, and 1,3-dioxopentanepropyltrimethoxysilane; the linear inorganic long chain has a degree of polymerization of 200-5000 and a molecular weight of 1-1,000,000.

[0033] In one embodiment of the present invention, in step S4, the molecular gear is one or a combination of more than one of inositol triphosphate, cyclohexanehexyl alcohol, and cyclohexanehexyl phosphate. The amount of the molecular gear added is 0.1 to 15 wt% of the mass of the linear inorganic long chain.

[0034] In one embodiment of the present invention, in step S4, the mixed solvent is 25-100 wt% of a linear inorganic long chain, and the mixed solvent is an alcohol / ether / amide mixed solvent, wherein the alcohol accounts for 70-90 wt%, the ether accounts for 5-20 wt%, and the amide accounts for 5-10 wt%; the alcohol solvent is selected from one or more combinations of methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, ethylene glycol, butanediol, hexanediol, or glycerol; the ether solvent is selected from one or more combinations of diethyl ether, diphenyl ether, tetrahydrofuran, and ethylene glycol dimethyl ether; the amide solvent is selected from one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0035] In one embodiment of the present invention, in step S4, the viscosity of the obtained solution is 10~500 mPa·s. The viscosity determination method referred to in the present invention is the "4-rotation method" in the standard "GB / T 10247-2008 Viscosity Test Method".

[0036] In one embodiment of the present invention, in step (4), the inorganic long-chain spinning solution has a solid content of 10-50 wt%, a viscosity of 10-500 mPa·s, an electrical conductivity of 1-100 μS / cm, a surface tension of 30-120 mN / m, a specific viscosity of 0.3-0.9, and a stable storage time of more than 60 days. It can be directly used for spinning to prepare precursor nanofibers with a diameter of 200-1000 nm. In the present invention, the degree of polymerization is based on the number of repeating units, that is, the average number of repeating units contained in the macromolecular chain of the sol polymer. The average molecular weight of the sol molecules is first obtained by gel chromatography, and then the degree of polymerization is obtained by dividing the average molecular weight by the molecular weight of the repeating units. The electrical conductivity is tested according to the standard "GB / T 11007-2008 Test Method for Electrical Conductivity Meter". The surface tension is tested according to the standard "GB-T 22237-2008 Determination of Surface Tension of Surfactants". The fiber diameter was tested using SEM and then measured using ImageJ.

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Any preparation methods, materials, structures, or compositional ratios not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0038] Example 1 This embodiment describes a method for the controllable synthesis, chain extension, and spinning of linear inorganic molecular chains. The specific steps are as follows: Step 1: Terephthalic acid was diluted with toluene at a volume ratio of 1:10. Then, under argon atmosphere, -5℃ and stirring speed of 500 rpm / min, the diluted terephthalic acid was added dropwise to tetrabutyl titanate at a rate of 0.02 wt% / s of the metal alkoxide monomer mass. The terephthalate group was used as an intermediate to link the titanium alkoxide monomers. Then, acetylacetone was added to replace the remaining active groups of the titanium alkoxide, forming a homogeneous transparent solution of the linear pre-coordinated framework of the titanium alkoxide. In the homogeneous transparent solution, the content of tetrabutyl titanate was 30 wt%, the content of acetylacetone was 4 wt%, the content of terephthalic acid was 6 wt%, and the content of toluene was 60 wt%.

[0039] Step 2: Add hydrochloric acid to the homogeneous transparent solution of the linear pre-coordinated framework of the above titanium alkoxide to adjust the pH of the solution to 3. Then add 12 wt% of poly(N-isopropylacrylamide) hydrogel microspheres (the microspheres were prepared by dissolving 3.8 g of N-isopropylacrylamide, 0.066 g of N,N-methylenebisacrylamide, and 0.15 g of sodium dodecyl sulfate in 240 ml of water, stirring continuously for 1 hour, and purifying the reaction solution with N2 for 40 minutes to remove oxygen). Then place the continuously purified reaction solution into a 70°C water bath. 0.166 g of ammonium persulfate was dissolved in 10 ml of water and added to the above solution to initiate an emulsification polymerization reaction for 4 hours. After the reaction, the mixture was cooled to room temperature. Purification was then performed by distillation dialysis and electric field dialysis, respectively. The prepared microspheres had a particle size of 5 μm, a water content of 90%, and a response temperature of 32 °C. Water molecules were released by controlling the temperature at 37 °C, with the total amount of water introduced being 10 wt% of the metal alkoxide monomer mass. The reaction was then carried out at 80 °C under a negative pressure suction pressure of -0.1 MPa for 2 hours to obtain linear inorganic molecular chains with a degree of polymerization of 45.

[0040] Step 3: Then, 2 wt% of titanium dichlorodecane, a metal alkoxide monomer, was used to extend the inorganic molecular chain. Then, 8 wt% of 4-azidobenzoic acid, a metal alkoxide monomer, was added, and the chain was capped by ultraviolet light to obtain a linear inorganic long chain with a degree of polymerization of 750 and a molecular weight of 220,000.

[0041] Step 4: Add 5 wt% (by weight) of the linear inorganic long-chain inositol triphosphate and 25 wt% (by weight) of a mixed solvent to the linear inorganic long-chain solution. The solvent composition includes ethanol (70 wt%), diethyl ether (20 wt%), and N,N-dimethylacetamide (10 wt%). The solution is stirred at 25°C until homogeneous. The resulting spinning solution has a solid content of 10 wt%, a viscosity of 200 mPa·s, a conductivity of 25 μS / cm, a surface tension of 45 mN / m, and a specific viscosity of 0.6. It can be directly used for spinning with a diameter of 680 nm. The degree of polymerization is based on the number of repeating units, i.e., the average number of repeating units in the sol polymer macromolecular chain. The average molecular weight of the sol molecules is first obtained by gel chromatography, and then the degree of polymerization is obtained by dividing the average molecular weight by the molecular weight of the repeating units. Electrical conductivity was tested according to the standard "GB / T 11007-2008 Test Method for Electrical Conductivity Meters". Surface tension was tested according to the standard "GB-T 22237-2008 Determination of Surface Tension of Surfactants". Fiber diameter was measured using ImageJ after SEM testing. Figure 2 This is a gel chromatography chromatogram of the linear inorganic long chain obtained in Example 1.

[0042] Example 2 This embodiment describes a method for the controllable synthesis, chain extension, and spinning of linear inorganic molecular chains. The specific steps are as follows: Step 1: Dilute terephthalic acid with toluene at a volume ratio of 1:5. Then, under argon atmosphere, -10℃, and stirring speed of 700 rpm / min, add the diluted terephthalic acid dropwise to aluminum sec-butoxide at a rate of 0.05 wt% / s (based on the mass of the metal alkoxide monomer). Use terephthalate as an intermediate to link the aluminum alkoxide monomers intermittently. Then, add acetylacetone to replace the remaining active groups of the aluminum alkoxide, forming a homogeneous transparent solution with a linear pre-coordinated framework of the aluminum alkoxide. In the homogeneous transparent solution, the content of aluminum sec-butoxide is 30 wt%, acetylacetone is 10 wt%, terephthalic acid is 10 wt%, and toluene is 50 wt%.

[0043] Step 2: Nitric acid was added to the homogeneous transparent solution of the linear pre-coordinated framework of the above aluminum alkoxide to adjust the pH to 3. Then, 20 wt% of poly(N-isopropylacrylamide) hydrogel microspheres (prepared by the same method as in Example 1) were added. The microspheres were allowed to release water molecules by controlling the temperature at 35°C. The total amount of water introduced was 15 wt% of the metal alkoxide monomer. The reaction was then carried out at a reaction temperature of 70°C and a negative pressure suction pressure of -0.1 MPa for 1 hour to obtain a linear inorganic molecular chain with a degree of polymerization of 40.

[0044] Step 3: The inorganic molecular chain was then extended by using 4 wt% (ethyl acetoacetate) diisopropoxy aluminate metal alkoxide monomer, followed by the addition of 10 wt% 3-azidopropyltrimethoxysilane metal alkoxide monomer, and the chain was capped by ultraviolet light to obtain a linear inorganic long chain with a degree of polymerization of 400 and a molecular weight of 100,000.

[0045] Step 4: Add 3 wt% (by weight) of inositol triphosphate and 30 wt% (by weight) of a mixed solvent to the linear inorganic long-chain solution. The solvent is composed of butanol (80 wt%), diethyl ether (15 wt%), and N,N-dimethylformamide (5 wt%). The solution is stirred at 25°C until homogeneous. The resulting spinning solution has a solid content of 20 wt%, a viscosity of 260 mPa·s, a conductivity of 30 μS / cm, a surface tension of 50 mN / m, and a specific viscosity of 0.7. It can be directly used for spinning with a diameter of 840 nm. The degree of polymerization is based on the number of repeating units, i.e., the average number of repeating units in the sol polymer macromolecule chain. The average molecular weight of the sol molecules is first obtained by gel chromatography, and then the degree of polymerization is obtained by dividing the average molecular weight by the molecular weight of the repeating units. Electrical conductivity was tested according to the standard "GB / T 11007-2008 Test Method for Electrical Conductivity Meters". Surface tension was tested according to the standard "GB-T 22237-2008 Determination of Surface Tension of Surfactants". Fiber diameter was measured using ImageJ after SEM testing.

[0046] Example 3 This embodiment describes a method for the controllable synthesis, chain extension, and spinning of linear inorganic molecular chains. The specific steps are as follows: Step 1: P-phenylenediamine was diluted with dichloromethane at a volume ratio of 1:8. Then, under argon atmosphere, -10℃, and stirring speed of 600 rpm / min, the diluted p-phenylenediamine was added dropwise to zirconium butoxide at a rate of 0.05 wt% / s (based on the mass of the metal alkoxide monomer). The p-phenylenediamine group was used as an intermediate to link the zirconium alkoxide monomers. Then, acetylacetone was added to replace the remaining active groups of the zirconium alkoxide, forming a homogeneous transparent solution of the linear pre-coordinated framework of the zirconium alkoxide. In the homogeneous transparent solution, the content of zirconium butoxide was 22 wt%, the content of acetylacetone was 6 wt%, the content of p-phenylenediamine was 8 wt%, and the content of dichloromethane was 64 wt%.

[0047] Step 2: Add hydrochloric acid to the homogeneous transparent solution of the linear pre-coordinated framework of the above-mentioned coordinated zirconium alkoxide to adjust the pH value to 4, and then add 15 wt% of poly(N-isopropylacrylamide) hydrogel microspheres (the specific preparation method is the same as in Example 1). By controlling the temperature at 37°C, the microspheres release water molecules, and the total amount of water introduced is 12 wt% of the mass of the metal alkoxide monomer. Then, react for 1 hour at a reaction temperature of 80°C and a negative pressure suction pressure of -0.1 MPa to obtain linear inorganic molecular chains with a degree of polymerization of 30.

[0048] Step 3: Then, the inorganic molecular chain was extended by using 3 wt% of bis(diethylcitrate)dipropoxide zirconium alkoxide monomer, followed by the addition of 7 wt% of 3-azidopropyltrimethoxysilane monomer, and the chain was capped by ultraviolet light to obtain a linear inorganic long chain with a degree of polymerization of 280 and a molecular weight of 80,000.

[0049] Step 4: Add 2 wt% (by weight) of cyclohexanehexanol and 25 wt% (by weight) of a mixed solvent to the linear inorganic long-chain solution. The solvent is composed of butanol (80 wt%), diethyl ether (15 wt%), and N,N-dimethylformamide (5 wt%). The solution is stirred at 25°C until homogeneous. The resulting spinning solution has a solid content of 15 wt%, a viscosity of 180 mPa·s, a conductivity of 20 μS / cm, a surface tension of 40 mN / m, and a specific viscosity of 0.4. It can be directly used for spinning with a diameter of 540 nm. The degree of polymerization is based on the number of repeating units, i.e., the average number of repeating units in the sol polymer macromolecular chain. The average molecular weight of the sol molecules is first obtained by gel chromatography, and then the degree of polymerization is obtained by dividing the average molecular weight by the molecular weight of the repeating units. Electrical conductivity was tested according to the standard "GB / T 11007-2008 Test Method for Electrical Conductivity Meters". Surface tension was tested according to the standard "GB-T 22237-2008 Determination of Surface Tension of Surfactants". Fiber diameter was measured using ImageJ after SEM testing.

[0050] Example 4 As a specific example of the present invention, after protonation of the silicon source, linear inorganic molecular chains can also be synthesized, extended, and spun into fibers. The specific steps are as follows: Step 1: Mix hydrochloric acid, anhydrous ethanol and tetraethyl orthosilicate to prepare a silanol solution with pH=1 and a tetraethyl orthosilicate content of 80wt%.

[0051] Step 2: Dilute terephthalic acid with dichloromethane at a volume ratio of 1:10. Then, under argon atmosphere, -10℃ and stirring speed of 700 rpm / min, add the diluted terephthalic acid dropwise to the silanolate solution at a rate of 0.05 wt% / s of the silanolate monomer mass. Use terephthalate as an intermediate to link the silanolate monomers interspersed. Then, add ethylenediamine to replace the remaining active groups of the silanolate to form a linear pre-coordinated framework of the silanolate structure, wherein the content of tetraethyl orthosilicate is 30 wt%, the content of ethylenediamine is 4 wt%, the content of terephthalic acid is 6 wt%, and the content of dichloromethane is 60 wt%.

[0052] Step 3: Adjust the pH of the homogeneous transparent solution of the linear pre-coordinated framework of the above-mentioned silanol salt to 3, then add poly(N-isopropylacrylamide) hydrogel microspheres (the specific preparation method is the same as in Example 1), and release water molecules from the microspheres by controlling the temperature to 37°C. The total amount of water introduced is 10 wt% of the inorganic alkoxide monomer mass. Then, react for 1 hour at a reaction temperature of 80°C and a negative pressure suction pressure of -0.1 MPa to obtain linear inorganic molecular chains with a degree of polymerization of 50.

[0053] Step 4: The inorganic molecular chain was then extended by adding 3 wt% of bis(ethyl acetoacetate) titanate diisopropyl silanate monomer, followed by adding 7 wt% of 3-azidopropyltrimethoxysilane monomer and end-capping the chain with ultraviolet light to obtain a linear inorganic long chain with a degree of polymerization of 600.

[0054] Step 5: Add 2 wt% (by weight) of cyclohexanehexyl alcohol and 25 wt% (by weight) of a mixed solvent to the linear inorganic long-chain solution. The alcohol is butanol, accounting for 80 wt% of the mixed solvent; the ether is diethyl ether, accounting for 15 wt% of the mixed solvent; and the amide is N,N-dimethylformamide, accounting for 5 wt% of the mixed solvent. Stir the above solution evenly at 25°C. The resulting spinning solution has a solid content of 25 wt%, a viscosity of 360 mPa·s, a conductivity of 35 μS / cm, a surface tension of 55 mN / m, and a specific viscosity of 0.5. It can be directly used for spinning with a diameter of 800 nm. The degree of polymerization is based on the number of repeating units, i.e., the average number of repeating units contained in the sol polymer macromolecular chain. The average molecular weight of the sol molecules is first obtained by gel chromatography, and then the degree of polymerization value is obtained by dividing the average molecular weight by the molecular weight of the repeating units. Electrical conductivity was tested according to the standard "GB / T 11007-2008 Test Method for Electrical Conductivity Meters". Surface tension was tested according to the standard "GB-T 22237-2008 Determination of Surface Tension of Surfactants". Fiber diameter was measured using ImageJ after SEM testing.

[0055] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for controllable synthesis, chain extension and spinning of linear inorganic molecular chains, characterized in that, Includes the following steps: S1. A linear, rigid bidentate linker is used to link metal alkoxide monomers to form a linear linking structure. Then, a flexible, bidentate stabilizer is added to replace the remaining active groups on the metal alkoxide monomers to form a stable linear pre-coordinated framework. S2. The linear connection structure of the linear pre-coordinated framework is transformed into a metal-oxygen-metal structure through hydrolysis-condensation reaction to obtain a low-polymerization degree linear inorganic molecular chain. S3. Use a metal-centered bifunctional chain extender to linearly extend low-polymerization-degree linear inorganic molecular chains, and then use an end-capping agent to terminate the chain extension reaction to obtain high-polymerization-degree linear inorganic long chains. S4. Add molecular gears and mixed solvent to the solution of the linear inorganic long chain to prepare a linear inorganic long chain spinning solution, and then prepare precursor nanofibers by spinning.

2. A process for the controllable synthesis, chain extension and spinning of linear inorganic molecular chains as claimed in claim 1, wherein, In S1, specific The process includes the following: A nonpolar solvent is added to a linear, rigid bidentate linker for dilution. The diluted solution is then slowly added dropwise to a metal alkoxide solution under an inert atmosphere, low temperature, and high-speed stirring. The linker acts as an intermediate to intersect the metal alkoxide monomers, forming a linear linkage structure. A flexible, bidentate stabilizer is then added to replace the remaining active groups on the metal alkoxide monomers, forming a stable linear pre-coordinated framework.

3. A process for the controllable synthesis, chain extension and spinning of linear inorganic molecular chains as claimed in claim 1, wherein, In S1, the metal alkoxide monomer contains at least three hydrolyzable alkoxy groups; The metal alkoxide is selected from one or more combinations of titanium source, zirconium source, aluminum source, gallium source, niobium source, hafnium source, tantalum source, and tin source; The titanium source is selected from one or more combinations of titanium tetramethanol, titanium tetraethanol, titanium n-propoxide, titanium isopropoxide, titanium n-butoxide, titanium isobutoxide, titanium tert-butoxide, titanium tetrapentoxide, and titanium isooctoxide. The zirconium source is selected from one or more combinations of zirconium tetramethanol, zirconium tetraethanol, zirconium n-propoxide, zirconium isopropoxide, zirconium n-butoxide, zirconium isobutoxide, zirconium tert-butoxide, and zirconium tetrapentoxide. The aluminum source is selected from one or more combinations of aluminum trimethoxy, aluminum triethanolamine, aluminum tri-n-propoxy, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, and aluminum tert-butoxide. The gallium source is selected from one or more combinations of gallium isopropoxide and gallium tert-butoxide; The niobium source is selected from one or more combinations of niobium isopropoxide and niobium n-butoxide; The hafnium source is selected from one or more combinations of tetramethanol hafnium, tetraethanol hafnium, n-propanol hafnium, isopropanol hafnium, n-butanol hafnium, isobutanol hafnium, tert-butanol hafnium, and tetrapentanol hafnium; The tantalum source is selected from one or more combinations of tantalum isopropoxide and tantalum n-butoxide; The tin source is selected from one or more combinations of tin tetramethanol, tin tetraethanol, tin n-propoxide, tin isopropoxide, tin n-butoxide, tin isobutoxide, tin tert-butoxide, and tin tetrapentoxide. The linear, rigid bidentate linker has a conjugated aromatic ring or a rigid heterocyclic skeleton, with two coordinating atoms located at para or linearly symmetric sites, which can coordinate with different metal alkoxide monomers respectively, thus linearly linking the metal alkoxide monomers. The linear, rigid bidental connector is selected from one or more combinations of p-phenylenediamine, 1,4-naphthylenediamine, terephthalic acid, or 1,4-diphenylphenol. The flexible, bidentate stabilizer is selected from one or more combinations of ethylenediamine, tetramethylethylenediamine, and acetylacetone.

4. A process for the controllable synthesis, chain extension and spinning of linear inorganic molecular chains as claimed in claim 2, wherein, In S1, the nonpolar solvent is one or a combination of toluene, p-xylene, carbon tetrachloride, and dichloromethane; The dilution process involves diluting a linear, rigid bidental connector with a nonpolar solvent at a volume ratio of 1:2 to 1:

10. The inert atmosphere is one or more combinations of nitrogen, helium, neon, argon, krypton, and xenon atmospheres; The low temperature condition is -20~0℃; The slow dripping rate is 0.01~0.2wt% / s of the metal alkoxide monomer mass; The high-speed stirring conditions are 300~1000 rpm.

5. A process for controllable synthesis, chain extension and spinning of linear inorganic molecular chains as claimed in claim 1, wherein, In S2, specifically The process includes the following: The pre-coordinated framework solution prepared by S1 was adjusted to acidity. Then, thermosensitive hydrogel microspheres were added. Water in the microspheres was released by low-temperature heating. Under high-temperature heating and negative pressure suction, the linear connection structure of the pre-coordinated framework was transformed into a metal-oxygen-metal structure through hydrolysis-condensation reaction, and a low degree of polymerization linear inorganic molecular chain was initially obtained. The temperature-sensitive hydrogel microspheres are selected from one or more combinations of poly(N-isopropylacrylamide) hydrogel microspheres, poly(N-isopropylacrylamide-acrylic acid) hydrogel microspheres, poly(N-isopropylacrylamide-hydroxyethyl methacrylate) hydrogel microspheres, and carboxymethyl chitosan hydrogel microspheres. The total water content of the thermosensitive hydrogel microspheres is 5-20 wt% of the metal alkoxide monomer. The low-temperature heating temperature is 5~50℃.

6. A process for the controllable synthesis, chain extension and spinning of linear inorganic molecular chains as claimed in claim 5, wherein, In S2, the acidity is to make the solution pH=1~5. The way to adjust it to acidity is to add an inorganic acid, which is selected from one or more combinations of hydrochloric acid, nitric acid, and phosphoric acid. The high-temperature heating conditions are 60~150℃, the negative pressure suction pressure is -0.1~0MPa, and the reaction time is 0.1~8h; The degree of polymerization of the low-polymerization linear inorganic molecular chain is 10~50.

7. A process for the controllable synthesis, chain extension and spinning of linear inorganic molecular chains as claimed in claim 1, wherein, S3 specifically includes the following processes: A bifunctional chain extender centered on a metal element is added to the solution of the low-polymerization-degree linear inorganic molecular chain obtained in S2 to extend the low-polymerization-degree linear inorganic molecular chain. Then, the chain extension reaction is terminated by a capping agent to obtain a high-polymerization-degree linear inorganic long chain with controllable polymerization degree.

8. A process for the controllable synthesis, chain extension and spinning of linear inorganic molecular chains according to claim 7, characterized in that, In S3, the metal element-centered bifunctional chain extender is selected from one or more of the following: diisopropoxydiacetylacetonitrile, diisopropyl bis(ethyl acetoacetate)titanate, dizirconia di(diethylcitrate)propoxide, diisopropoxyaluminate (ethyl acetoacetate), titanium dichlorocerocene, zirconium dichlorocerocene, hafnium dichlorocerocene, molybdenum dichlorocerocene, vanadium dichlorocerocene, and niobium dichlorocerocene. The amount of the bifunctional chain extender centered on the metal element is 1~10 wt% of the mass of the metal alkoxide monomer; The end-capping agent is selected from one or more of common chemical end-capping agents, visible light responsive end-capping agents, and ultraviolet light responsive end-capping agents; The amount of the capping agent added is 0.1~10 wt% of the mass of the metal alkoxide monomer; The common chemical end-capping agent is selected from one or more of methyl isocyanate and phenyl isocyanate; The visible light end-capping agent is selected from one or more of 2-diazo-1-naphthol-5-sulfonyl chloride, ethyl diazonyl chloride, and 4-azido-2,3,5,6-tetrafluorobenzoic acid; The ultraviolet light responsive end-capping agent is selected from one or more of 4-azidobenzoic acid, 3-azidopropyltrimethoxysilane, and 1,3-dioxopentanepropyltrimethoxysilane; The linear inorganic long chain has a degree of polymerization of 200 to 5000 and a molecular weight of 1 to 1 million.

9. A process for controllable synthesis, chain extension and spinning of linear inorganic molecular chains as claimed in claim 1, wherein, S4, specific The process includes the following: Molecular gears and mixed solvents are added to a solution of linear inorganic long chains to prepare a linear inorganic long chain spinning solution, and then precursor nanofibers are prepared by spinning. The molecular gear is added at a rate of 0.1 to 15 wt% of the mass of the linear inorganic long chain, and the mixed solvent is added at a rate of 25 to 100 wt% of the mass of the linear inorganic long chain.

10. A process for the controllable synthesis, chain extension and spinning of linear inorganic molecular chains according to claim 9, characterized in that, The molecular gear is selected from one or more of the following: inositol triphosphate, cyclohexanehexol, and cyclohexanehexol phosphate. The mixed solvent is a solvent prepared by mixing alcohols, ethers, and amides, wherein the alcohol accounts for 70-90 wt%, the ether accounts for 5-20 wt%, and the amide accounts for 5-10 wt%. The alcohol is selected from one or more combinations of methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, ethylene glycol, butanediol, hexanediol, and glycerol; The ether is selected from one or more combinations of diethyl ether, diphenyl ether, tetrahydrofuran, and ethylene glycol dimethyl ether; The amide is selected from one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; The linear inorganic long-chain spinning solution has a solid content of 10-50 wt%, a viscosity of 10-500 mPa·s, an electrical conductivity of 1-100 μS / cm, a surface tension of 30-120 mN / m, and a specific viscosity of 0.3-0.

9. The stable storage time is greater than 60 days, and it can be directly used for spinning; The precursor nanofibers have a diameter of 200~1000nm.

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