Thiophene polyamide and preparation method thereof, nanofiber membrane and preparation method and application thereof

Abstract

The invention relates to the technical field of new materials, and discloses thiophene polyamide and a preparation method thereof, a nanofiber membrane and a preparation method and application of the nanofiber membrane, and the thiophene polyamide contains a structural unit shown in the formula (I); wherein X and Y are respectively and independently selected from hydrogen, alkyl, halogen, amino and amino derivatives. The nanofiber membrane prepared by taking the thiophene polyamide as a raw material has the characteristics of high mechanical strength, high heat resistance, high hydrophobicity and antibacterial property, can be used for a long time under a high-temperature working condition, and has a wide application prospect in the fields of water treatment, automobile fuel filter screens, new energy batteries, automobile air conditioner filter screens, medical protective articles and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new materials, and particularly relates to a thiophene polyamide, a preparation method thereof, a nanofiber membrane and a preparation method and application thereof. BACKGROUND

[0002] Aramid nanofibers (ANFs) prepared by using poly-p-phenyleneterephthalamide (PPTA) fibers (Kevlar fibers) as a representative have a unique one-dimensional structure and retain excellent mechanical properties and heat resistance of Kevlar fibers, and are widely used for preparing high-performance and functionalized materials.

[0003] ANFs are a new type of high-performance nanofiber with a highly compact molecular structure. Due to high crystallinity, high strength and modulus, ANFs are often introduced into polymers as reinforcing fillers to prepare high-performance composite materials. The surface of ANFs is relatively smooth, and the content of surface active groups is relatively low, so that the surface polarity of ANFs is relatively low, and the surface chemical inertness is relatively strong. In addition, the macroscopic scale of aramid pulp and chopped fibers used for preparing ANFs is micron level, which makes the interface interaction between the internal components of ANFs weak, and there are a large number of cavities and defects in the material, which greatly affects the insulation performance. Therefore, how to further improve the interaction between the internal components of ANFs and make the material more uniform and densified is the key to improving the insulation performance.

[0004] The most commonly used method for preparing ANFs is deprotonation etching. PPTA fibers are dissolved in a dimethyl sulfoxide / potassium hydroxide solution, and aramid nanofiber dispersion is prepared by deprotonation etching. However, due to the rigid molecular chain conformation and strong interchain hydrogen bonding of Kevlar fibers, Kevlar fibers can only be dissolved in strong protonic acids such as concentrated sulfuric acid, methanesulfonic acid and chlorosulfonic acid. Limited by the harsh dissolution conditions of Kevlar fibers, it is difficult to directly prepare aramid nanofibers by electrospinning. In addition, the microscale size of Kevlar fibers is small, and molecular-level compatibility cannot be achieved, so there are still a large number of interface defects.

[0005] To realize the electrospinning of aramid fibers, a flexible structure is usually introduced into PPTA by copolymerization or covalent grafting to modify PPTA. Although these methods can obtain aramid with good electrospinning performance by improving the solubility, the mechanical properties of the aramid will also be severely reduced compared with PPTA.

[0006] CN113980312A discloses a high-temperature-resistant high-breakdown-strength intrinsic aramid film and a preparation method thereof. The method comprises (1) adding aromatic diamine monomers and aromatic diacyl chloride monomers into a solvent to obtain an aramid polymer solution; (2) coagulating the aramid polymer solution in a coagulation bath to form a nascent film, which is then washed with water and dried to obtain the nascent film; and (3) soaking the nascent film in an acid solution, taking it out, drying it, and annealing it to obtain the aramid film. The aramid film in the method is prepared by adding a spinning aid to a deprotonated PPTA nanofiber dispersion. Since the spinning aid uses a flexible chain polymer (such as polyethylene oxide and polyvinyl pyrrolidone), the final para-aramid nanofiber film has excellent mechanical properties and high-temperature breakdown strength. However, the heat resistance and thermal stability of the film are not disclosed. In addition, the preparation method uses diacyl chloride monomers as raw materials, which are highly corrosive and irritating, and generate a large amount of acid gas during the reaction, causing serious environmental pollution.

[0007] CN109942810A discloses an aromatic heterocyclic polyamide composite film with high breakdown strength and a preparation method thereof. The aromatic heterocyclic polyamide composite film is prepared by mixing a solution of surface-grafted alkenyl nanosilica and aromatic polyamide, and then processing it into a film. The aromatic polyamide has an amide obtained by reacting aromatic diamine and aromatic diacyl chloride as a repeating structural unit, and a polymer with alkenyl groups at both ends of the molecular chain. The composite film prepared by this method has a tensile strength of 280-350 MPa and a breakdown strength of 470-650 kV / mm at room temperature, which significantly improves the breakdown strength and tensile strength. However, the method does not disclose that the composite film has high-temperature resistance. Moreover, the aromatic heterocyclic polyamide composite film contains silica nanoparticles, which can form holes under high voltage during long-term use, leading to failure of the film.

[0008] CN116200881A discloses a kind of heterocyclic aramid nanofiber membrane and its preparation method, wherein, preparation method includes the steps: the aromatic heterocyclic diamine monomer containing benzimidazole or benzoxazole, aromatic diamine monomer and aromatic diacyl chloride monomer are added in solvent and reacted, obtain heterocyclic aramid solution;Small molecule physical crosslinking agent is added in heterocyclic aramid solution, after mixing evenly, spinning dope solution is prepared;Spinning dope solution is obtained by electrospinning process, and the nascent heterocyclic aramid nanofiber membrane is oriented along the direction of drum rotation;The nascent heterocyclic aramid nanofiber membrane is soaked in alkali solution and distilled water respectively, and then taken out, and after normal pressure drying or freeze drying, pure heterocyclic aramid nanofiber membrane is obtained after annealing treatment.The method introduces benzimidazole unit or benzoxazole unit on the basis of PPTA molecular chain, and the heterocyclic aramid fiber material prepared has good solubility and excellent mechanical properties, but this kind of heterocyclic aramid fiber lacks effective topological entanglement in solution due to the nature of molecular chain rigidity, therefore, in order to overcome the poor electrospinning, small molecule physical crosslinking agent (sulfuric acid, oxalic acid, phosphoric acid or polyphosphoric acid) needs to be added in the electrospinning process, to build hydrogen bond crosslinking network between rigid heterocyclic aramid molecular chain to equivalent electrospinning required molecular chain topological entanglement, and then physical crosslinking agent needs to be removed by washing with alkali solution and distilled water, and the preparation method is complex.

[0009] In summary, the existing aramid nanofiber research mainly focuses on modifying synthetic materials to improve the mechanical properties and heat resistance of aramid nanomaterials. The existing aramid nanofiber mainly uses PPTA or modified PPTA as the synthetic raw material. On the one hand, due to the rigid molecular chain conformation and strong interchain hydrogen bonding of PPTA fiber, the electrospinning property of PPTA fiber is poor, and the main chain of modified PPTA fiber is aliphatic flexible structure, which cannot meet the use requirements in high temperature environment. On the other hand, the raw material of synthetic polyamide produced domestically has a large gap with foreign products, and cannot meet the requirements of medium and high-end polyamide materials. The existing raw material of synthetic polyamide is mainly imported products, causing excessive dependence on imported products.

[0010] In addition, with "carbon peak" and "carbon neutral" becoming the focus of social attention, the research and development of bio-based materials has also received widespread attention from the academic and industrial communities. Therefore, in order to reduce the excessive dependence on foreign products and enhance the market competitiveness of state-owned polyamide, the state and enterprises are vigorously promoting the localization of polyamide products, and there is an urgent need to develop a new bio-based polyamide material to provide new raw materials for the research and development of medium and high-end polyamide modified materials for the preparation of high-performance aramid nanofiber membrane. SUMMARY

[0011] The present application aims to overcome the problems of single type of polyamide material and poor electrospinning in the synthesis process of existing aramid material, and provides a thiophene polyamide, a preparation method thereof, a nanofiber membrane and a preparation method and application thereof.

[0012] To achieve the above-mentioned object, the present application provides a thiophene polyamide, wherein the thiophene polyamide contains a structural unit shown in formula (I).

[0013]

[0014] wherein X and Y are each independently selected from hydrogen, alkyl, halogen, amino and amino derivatives.

[0015] The present application provides a preparation method of a thiophene polyamide, wherein the method comprises the following steps:

[0016] (1) pre-polymerization of diamine monomers and dicarboxylic ester monomers in the presence of organic solvent A in an inert gas;

[0017] (2) adding a catalyst to perform polycondensation reaction to obtain the thiophene polyamide;

[0018] wherein the dicarboxylic ester monomers are selected from dicarboxylic ester compounds containing thiophene groups.

[0019] The present application provides a preparation method of a nanofiber membrane, wherein the method comprises the following steps:

[0020] (1) adding the thiophene polyamide and optional additives in organic solvent B, mixing and stirring to obtain a nanospinning stock solution;

[0021] (2) electrospinning treatment of the nanospinning stock solution to obtain the nanofiber membrane.

[0022] The present application provides a nanofiber membrane, wherein the tensile stress of the nanofiber membrane is ≥40 MPa, the tensile strain is ≥4%, the heat resistance temperature (T5%) is ≥350℃, and the antibacterial rate is ≥90%.

[0023] Preferably, the tensile stress of the nanofiber membrane is 40-90 MPa, the tensile strain is 4-30%, the heat resistance temperature (T5%) is 350-505℃, and the antibacterial rate is 94-96%.

[0024] The present application provides an application of the nanofiber membrane in water treatment, automobile fuel filter screen, new energy battery, automobile air conditioner filter screen and medical protective products.

[0025] Through the above technical solutions, the technical solutions of the present application have the following beneficial effects:

[0026] (1) The present invention uses dimethyl ester derived from biomass cellulose such as straw, rice husk, and coconut flakes or biomass sugar formed by hydrolysis as raw material to prepare thiophene polyamide. The thiophene polyamide provided by the present invention is a bio-based polyamide. The raw materials for synthesis are widely available, renewable, and belong to bio-based environmentally friendly polymer materials.

[0027] (2) The present invention uses thiophene polyamide to prepare heterocyclic aramid nanofiber membranes, which enriches the types of polymer materials;

[0028] (3) The present invention uses thiophene polyamide as raw material to introduce thiophene groups into aramid fibers, which improves the heat resistance, mechanical strength and hydrophobicity of nanofiber membranes, and also has antibacterial properties.

[0029] (4) The nanofiber membrane of the present invention has application prospects in a variety of fields, including water treatment, automotive fuel filter, new energy battery, automotive air conditioning filter, medical protective equipment and other fields with broad commercial prospects. Attached Figure Description

[0030] Figure 1 This is the nuclear magnetic resonance image of the thiophene polyamide solid Al prepared in Example 1 of this invention.

[0031] Figure 2 This is a finished product image of the nanofiber membrane B1 from Example 1 of the present invention.

[0032] Figure 3 This is a TGA test image of the nanofiber membrane B3 of Example 3 of the present invention.

[0033] Figure 4 This is a TGA test image of the nanofiber membrane B9 of Example 9 of the present invention.

[0034] Figure 5 This is a SEM scan of the nanofiber membrane B2 from Example 2 of the present invention.

[0035] Figure 6 This is the DMA stretching curve of the nanofiber membrane B3 in Example 3 of the present invention. Detailed Implementation

[0036] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0037] The first aspect of the present application provides a thiophene polyamide, wherein the thiophene polyamide contains a structural unit represented by formula (I);

[0038]

[0039] wherein X and Y are each independently selected from hydrogen, alkyl, halogen, amino and amino derivatives.

[0040] Preferably, X and Y are each independently selected from hydrogen.

[0041] According to some embodiments of the present application, the molar content of the structural unit represented by formula (I) in the thiophene polyamide is 5-80 mol% based on the total amount of the thiophene polyamide.

[0042] In the present application, the molar content of the structural unit represented by formula (I) in the thiophene polyamide can be determined by nuclear magnetic resonance method.

[0043] In the present application, preferably, the thiophene polyamide molecular chain can further contain at least two of structural unit B, structural unit C, structural unit D, structural unit E and structural unit F. The structural formulae of structural unit B, structural unit C, structural unit D, structural unit E and structural unit F are respectively represented by formulae (1)-(5):

[0044]

[0045]

[0046] wherein R1, R2, R3, R4 and R5 are each independently selected from substituted bridged ring group, unsubstituted bridged ring group, alkyl, spirocyclic group, heterocyclic group, phenyl and phenyl derivatives; preferably, R1, R2, R3, R4 and R5 are each independently selected from alkyl, heterocyclic group and phenyl.

[0047] Specifically, preferably, the thiophene polyamide molecular chain of the present application contains structural unit B represented by formula (1), structural unit E represented by formula (4) and formula (I); or the thiophene polyamide molecular chain of the present application contains structural unit B represented by formula (1), structural unit C represented by formula (2), structural unit E represented by formula (4) and formula (I); or the thiophene polyamide molecular chain of the present application contains structural unit B represented by formula (1), structural unit C represented by formula (2), structural unit D represented by formula (3), structural unit E represented by formula (4), structural unit F represented by formula (5) and formula (I).

[0048] In the present application, preferably, the molar content of the structural unit represented by formula (I) is 20-80 mol%. The molar content of each structural unit can be determined by nuclear magnetic resonance method or by the feeding ratio of each monomer raw material during polymerization.

[0049] According to some embodiments of the present application, the specific viscosity of the thiophene polyamide is 1.03-2.76 dL / g, preferably 1.55-2.76 dL / g.

[0050] In the present application, the test method of the specific viscosity of the thiophene polyamide includes the following steps: dissolving the thiophene polyamide in dimethylacetamide (DMAC), preparing a solution with a mass concentration of c0(g / mL), wherein the mass-volume ratio of the thiophene polyamide to the solvent is 1 g:(25-30) mL; adding the above solution into an Ubbelohde viscometer to determine the outflow time of the solution flowing through the two scale lines of the viscometer, recorded as t0(min); measuring the outflow time of DMAC flowing through the two scale lines of the viscometer, recorded as t1(min), and the specific viscosity is In(t0 / t1) / c0.

[0051] In the present application, when the specific viscosity of the thiophene polyamide meets the above-mentioned limited range, the thiophene polyamide contains a specific molecular weight and viscosity, thereby improving the heat resistance, mechanical strength and hydrophobicity of the nanofiber membrane.

[0052] The second aspect of the present application provides a preparation method of a thiophene polyamide, wherein the method includes the following steps:

[0053] (1) Pre-polymerizing diamine monomers and dicarboxylic ester monomers in the presence of an organic solvent A in an inert gas;

[0054] (2) Adding a catalyst to perform polycondensation reaction to obtain a thiophene polyamide;

[0055] The dicarboxylic ester monomers are selected from dicarboxylic ester compounds containing thiophene groups.

[0056] In the present application, the preparation method of the thiophene polyamide further includes washing, suction filtration and drying treatment, and the specific method includes adding tetrahydrofuran to the thiophene polyamide solution after the polycondensation reaction is completed, stirring, suction filtration, and then drying the obtained filter cake to obtain the thiophene polyamide solid.

[0057] In the present application, the preparation process of the thiophene polyamide belongs to an amination reaction, mainly including cleavage of ester bonds and formation of amide bonds, specifically including: in the reaction process, the ester bonds in the diformate monomers are broken into carboxyl groups, the carboxyl groups in the diformate monomers are connected with the amino end groups in the diamine monomers to form amide bonds, and small molecule water is lost at the same time, so as to obtain a thiophene-containing polyamide. The thiophene-containing polyamide obtained can be identified for the molecular structure by nuclear magnetic resonance spectroscopy.

[0058] According to some embodiments of the present application, the organic solvent A is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, dichloroethane, N,N-dimethylacetamide and N-methylpyrrolidone.

[0059] According to some embodiments of the present application, the catalyst is selected from at least one of tetrabutyl titanate, dioctyltin dilaurate and isopropyl tridodecylbenzenesulfonyl titanate, and preferably tetrabutyl titanate.

[0060] According to some embodiments of the present application, the conditions of the prepolymerization reaction include a temperature of 100-120℃ and a time of 1-3h.

[0061] According to some embodiments of the present application, the conditions of the polycondensation reaction include a temperature of 160-180℃ and a time of 3-5h.

[0062] In the present application, the temperature and time of the prepolymerization reaction affect the efficiency of the reaction, and the temperature / time of the polycondensation reaction affects the degree of polymerization. When the conditions of the prepolymerization reaction and the polycondensation reaction meet the above-mentioned limited ranges, the reaction efficiency is improved, the molecular weight and the distribution of the molecular weight of the prepolymer are controlled, the polyamide containing a specific content of thiophene amide groups is prepared, and the production efficiency and product performance are improved.

[0063] According to some embodiments of the present application, the molar ratio of the diformate monomers to the diamine monomers is (0.95-1.05):1.

[0064] In the present application, by controlling the amounts of the diformate monomers and the diamine monomers, the structure of the thiophene polyamide is regulated.

[0065] According to some embodiments of the present application, the diformate monomers are selected from thiophene dimethylate monomers or mixed monomers of thiophene dimethylate and a compound B; the compound B is selected from aromatic dimethylate and / or heterocyclic dimethylate.

[0066] Preferably, the molar amount of the thiophene dimethylate monomers is 3%-90% of the total molar amount of the diformate monomers and the diamine monomers.

[0067] In the present application, by controlling the proportion of the molar number of dimethyl thiophene dicarboxylate monomer in the total amount of the dicarboxylate monomer and diamine monomer, a polyamide with a specific content of thiophene groups is obtained, thereby improving the mechanical properties, heat resistance and antibacterial properties of the nanofiber membrane.

[0068] According to some embodiments of the present application, the mass ratio of the organic solvent A to the total of the dicarboxylate monomer and diamine monomer is (3-10):1, preferably (5-7):1.

[0069] According to some embodiments of the present application, the molar ratio of the catalyst to the dicarboxylate monomer is (0.001-0.05):1.

[0070] Preferably, the aromatic dicarboxylic acid dimethyl ester is selected from at least one of dimethyl isophthalate, dimethyl terephthalate, dimethyl naphthalene dicarboxylate and dimethyl 1,3,5-benzene tricarboxylate.

[0071] Preferably, the heterocyclic dicarboxylic acid dimethyl ester is selected from at least one of dimethyl pyridine dicarboxylate, dimethyl pyrazine dicarboxylate and dimethyl pyrimidine dicarboxylate.

[0072] According to some embodiments of the present application, the diamine monomer is selected from at least one of benzene diamine, aliphatic diamine and heterocyclic diamine.

[0073] Preferably, the benzene diamine is selected from at least one of 4,4'-(1,4-benzenediol) bisphenylamine, 2,2'-dimethyl-4,4'-diaminobiphenyl, m-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, naphthalene diamine and p-phenylenediamine, more preferably m-phenylenediamine and / or p-phenylenediamine.

[0074] Preferably, the aliphatic diamine is selected from at least one of ethylenediamine, propylenediamine, butylenediamine, pentanediamine, hexanediamine and nonanediamine, more preferably butylenediamine and / or pentanediamine.

[0075] Preferably, the heterocyclic diamine is selected from at least one of 2-(4-aminophenyl)-5-aminobenzoxazole, 2-(4-aminophenyl)-5-aminobenzimidazole, 3,4-diaminodiphenyl ether, 3,3-diaminodiphenyl sulfone, 4,4-diaminodiphenyl sulfone, 4,4'-bis(3-aminophenoxy)diphenyl sulfone, 4,4-diaminodiphenyl ether, 2,2'-bis(trifluoromethyl)diaminobiphenyl and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, more preferably at least one of 4,4-diaminodiphenyl ether, 2-(4-aminophenyl)-5-aminobenzimidazole and 4,4'-bis(3-aminophenoxy)diphenyl sulfone.

[0076] In the present application, the types of the dicarboxylic ester monomer and the diamine monomer are different, the structures of the prepared polymers are different, and the mechanical properties and thermal properties of the nanofiber membrane are affected. When the types of the dicarboxylic ester monomer and the diamine monomer meet the above-mentioned limited range, the thienyl group can be introduced into the aramid fiber, thereby preparing a nanofiber membrane containing a thienyl group, and improving the heat resistance, mechanical strength and hydrophobicity of the nanofiber membrane, and also having antibacterial properties.

[0077] In the present application, preferably, the thienyl polyamide molecular chain can also contain at least two of the structural units B, the structural unit C, the structural unit D from the diamine monomer, the structural unit E from the dicarboxylic ester monomer and the structural unit F from the dicarboxylic ester monomer.

[0078] In the present application, the structural formula of the structural unit B, the structural unit C, the structural unit D, the structural unit E and the structural unit F are respectively shown as formula (1)-(5):

[0079] wherein R1, R2, R3, R4 and R5 are independently selected from substituted bridged ring group, unsubstituted bridged ring group, alkyl group, spiro ring group, heterocyclic group, phenyl group and phenyl derivative; preferably, R1, R2, R3, R4 and R5 are independently selected from alkyl group, heterocyclic group and phenyl group.

[0080] In the present application, when the diamine monomer is phenyl diamine and aliphatic diamine, and the dicarboxylic ester monomer is dimethyl thienyl dicarboxylate, or when the diamine monomer is heterocyclic diamine and aliphatic diamine, and the dicarboxylic ester monomer is dimethyl thienyl dicarboxylate, the thienyl polyamide prepared by the above-mentioned method contains the structural units shown as formula (1), formula (2) and formula (I):

[0081] Preferably, in the thienyl polyamide, the molar ratio of the structural unit shown as formula (1), the structural unit shown as formula (2) and the structural unit shown as formula (I) is (0.5-1):(0.5-1):1. Specifically, when the diamine monomer is m-phenylenediamine and butanediamine, and the dicarboxylic ester monomer is dimethyl thienyl dicarboxylate, R1 is R2 is -(CH2)4-; when the diamine monomer is 4,4-diamino diphenyl ether and pentanediamine, and the dicarboxylic ester monomer is dimethyl thienyl dicarboxylate, R1 is R2 is -(CH2)4-; when the diamine monomer is 4,4-diamino diphenyl ether and pentanediamine, and the dicarboxylic ester monomer is dimethyl thienyl dicarboxylate, R1 is

[0082] In the present application, when the diamine monomer is a heterocyclic diamine and the dicarboxylate monomer is dimethylthiophene dicarboxylate, dimethylaromatic dicarboxylate and dimethylheterocyclic dicarboxylate, the thiophene polyamide prepared by the above method contains structural units represented by formulae (1), (4), (5) and (I):

[0083] Preferably, in the thiophene polyamide, the molar ratio of the structural unit represented by formula (1), the structural unit represented by formula (2), the structural unit represented by formula (4), the structural unit represented by formula (5) and the structural unit represented by formula (I) is (0.5-1):(0.5-1):(0.5-1):(0.5-1):1. Specifically, when the diamine monomer is 4,4-diaminodiphenyl ether and the dicarboxylate monomer is dimethylthiophene dicarboxylate, dimethylisophthalate and dimethylpyridine dicarboxylate, R1and R2are both R4is R5is

[0084] In the present application, when the diamine monomer is a heterocyclic diamine and the dicarboxylate monomer is dimethylthiophene dicarboxylate and dimethylheterocyclic dicarboxylate, the thiophene polyamide prepared by the above method contains structural units represented by formulae (1), (4) and (I):

[0085] Preferably, in the thiophene polyamide, the molar ratio of the structural unit represented by formula (1), the structural unit represented by formula (4) and the structural unit represented by formula (I) is (0.5-1):(0.5-1):1. Specifically, when the diamine monomer is 2-(4-aminophenyl)-5-aminobenzimidazole and the dicarboxylate monomer is dimethylthiophene dicarboxylate and dimethylpyrazine dicarboxylate, R1is R4is When the diamine monomer is 4,4'-bis(3-aminophenoxy)diphenyl sulfone and the dicarboxylate monomer is dimethylthiophene dicarboxylate and dimethylpyridine dicarboxylate, R1is R4is

[0086] In the present application, when the diamine monomer is a heterocyclic diamine and the dicarboxylate monomer is dimethylthiophene dicarboxylate and dimethylheterocyclic dicarboxylate, the thiophene polyamide prepared by the above method contains structural units represented by formulae (1), (2), (4) and (I):

[0087] Preferably, in the thiophene polyamide, the molar ratio of the structural unit represented by formula (1), the structural unit represented by formula (2), the structural unit represented by formula (4), and the structural unit represented by formula (I) is (0.5-1) : (0.5-1) : (0.5-1) : 1. Specifically, when the diamine monomer is 4,4-diaminodiphenyl ether and p-phenylenediamine, and the dicarboxylate monomer is dimethyl thiophene dicarboxylate and dimethyl pyridine dicarboxylate, R1 is R2 is and R4 is When the diamine monomer is 4,4-diaminodiphenyl ether and m-phenylenediamine, and the dicarboxylate monomer is dimethyl thiophene dicarboxylate and dimethyl pyridine dicarboxylate, R1 is R2 is and R4 is

[0088] In the present application, when the diamine monomer is a heterocyclic diamine and a benzene-based diamine, and the dicarboxylate monomer is dimethyl thiophene dicarboxylate, an aromatic dimethyl dicarboxylate, and a heterocyclic dimethyl dicarboxylate, the thiophene polyamide prepared according to the above method contains the structural units represented by formulas (1), (2), (3), (4), (5), and (I):

[0089] Preferably, in the thiophene polyamide, the molar ratio of the structural unit represented by formula (1), the structural unit represented by formula (2), the structural unit represented by formula (3), the structural unit represented by formula (4), the structural unit represented by formula (5), and the structural unit represented by formula (I) is (0.5-1) : (0.5-1) : (0.5-1) : (0.5-1) : (0.5-1) : 1. Specifically, when the diamine monomer is 4,4-diaminodiphenyl ether, p-phenylenediamine, and 2-(4-aminophenyl)-5-aminobenzimidazole, and the dicarboxylate monomer is dimethyl thiophene dicarboxylate, dimethyl terephthalate, and dimethyl pyridine dicarboxylate, R1 is R2 is R3 is R4 is and R5 is

[0090] In the present application, when the diamine monomer is a heterocyclic diamine, and the dicarboxylate monomer is dimethyl thiophene dicarboxylate and a heterocyclic dimethyl dicarboxylate, the thiophene polyamide prepared according to the above method contains the structural units represented by formulas (1), (2), (4), and (I):

[0091] Preferably, in the thiophene polyamide, the molar ratio of the structural unit represented by formula (1), the structural unit represented by formula (2), the structural unit represented by formula (4) and the structural unit represented by formula (I) is (0.5-1):(0.5-1):(0.5-1):1. Specifically, when the diamine monomer is 4,4-diaminodiphenyl ether and 2-(4-aminophenyl)-5-aminobenzimidazole, and the dicarboxylate monomer is dimethyl thiophene dicarboxylate and dimethyl pyridine dicarboxylate, R1 is R2 is R4 is

[0092] The third aspect of the present application provides a method for preparing a nanofiber membrane, wherein the method comprises the following steps:

[0093] (1) adding thiophene polyamide and optional additives in an organic solvent C, mixing and stirring to obtain a nanospinning stock solution;

[0094] (2) performing electrospinning treatment on the nanospinning stock solution to obtain a nanofiber membrane.

[0095] According to some embodiments of the present application, the method of electrospinning treatment comprises: injecting the nanospinning stock solution into a syringe and performing electrospinning treatment with a flat needle.

[0096] According to some embodiments of the present application, the conditions of electrospinning treatment comprise: voltage 6-10 kV, extrusion rate 2-2.4 mL / h, drawing air pressure 0.06-0.08 MPa, spinneret inner diameter 0.1-0.4 mm, and receiving distance 18-20 cm.

[0097] Preferably, the average diameter of the nanofibers in the nanofiber membrane is 100-350 nm.

[0098] In the present application, when the spinning voltage of electrospinning is low, it is difficult to overcome the surface tension of the nanospinning stock solution due to the small electric field force, which hinders the drawing and splitting of the spinning solution, so that the diameter of the nanofiber formed is large; as the spinning voltage gradually increases, the electric field strength becomes larger and larger, the spinning solution jet is more easily stretched and split, forming nanofibers with a smaller diameter; if the spinning voltage is too high, the electric field strength is too large, which leads to an increase in the amount of spinning solution jet and the speed of the jet each time, which is not conducive to the stretching and splitting of the spinning solution jet, so that the diameter of the nanofiber becomes larger and the uniformity becomes worse, resulting in a beaded or beaded nanofiber membrane.

[0099] In the present application, the extrusion rate of nanospinning in the electrospinning process is determined by the propelling speed of the injector. Adjusting the extrusion rate of spinning not only determines the production efficiency of nanofiber, but more importantly, it affects the stability of the liquid droplet of the needle and the diameter of the fiber. In the process of preparing nanofiber, with the increase of the extrusion rate of spinning, the flight process of the nanospinning solution between the needle tip and the metal collector is too short to be completely dried, resulting in the gradual increase of the diameter of the prepared nanofiber membrane, and even the formation of beaded fibers.

[0100] In the present application, the receiving distance refers to the distance between the spinning needle and the collector, and the size of the receiving distance affects the strength of the electric field and the evaporation of the solvent in the nanospinning solution, thereby affecting the diameter of the nanofiber in the prepared nanofiber membrane. For example, if the distance is too short, the solvent may not evaporate sufficiently, which may result in the formation of fused fibers. Preferably, when the receiving distance of the present application is set to the above range, the solvent of the nanospinning solution has sufficient evaporation time, thereby obtaining a deposited and dried nanofiber bundle.

[0101] In the present application, when the process conditions of electrospinning meet the above range, the electrospinning process proceeds smoothly, and the prepared nanofiber membrane is continuous, smooth in surface, good in uniformity, small in diameter of nanofiber, and has excellent mechanical properties, thermal stability and hydrophobicity.

[0102] According to some embodiments of the present application, the organic solvent C is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, dichloromethane, chloroform, ethanol, methanol, n-pentane and n-butane.

[0103] According to some embodiments of the present application, the auxiliary agent is selected from at least one of lithium chloride, calcium chloride, lithium bromide, calcium bromide, boehmite, silicon dioxide, aluminum oxide, zirconium oxide, polyethylene glycol and polyethylene glycol ether.

[0104] In the present application, the auxiliary agent functions to adjust the electrical conductivity and viscosity, and to improve the quality of the nanofiber membrane. When the type of the auxiliary agent is selected within the above defined range, the electrical conductivity of the spinning solution can be effectively adjusted, which is helpful for the smooth progress of electrospinning.

[0105] According to some embodiments of the present application, the amount of the thiophene polyamide is 1-15 wt% and the amount of the auxiliary agent is 0.05-5 wt% based on the mass of the organic solvent C.

[0106] Preferably, the amount of the thiophene polyamide is 5-15 wt% and the amount of the auxiliary agent is 0.1-5 wt% based on the mass of the organic solvent C.

[0107] In the present application, the amount of organic solvent C and thiophene polyamide will affect the concentration and viscosity of the nanospinning dope. For example, if the amount of thiophene polyamide is too small, the concentration of the obtained nanospinning dope is low, and the thiophene polyamide is broken before reaching the collector, resulting in the formation of beaded or string-shaped nanofiber membranes; and if the amount of thiophene polyamide is too large, the concentration of the nanospinning dope is too high, making the nanospinning dope too viscous, hindering the flow of the dope, and obtaining defective or beaded nanofiber membranes. When the amount of organic solvent C and thiophene polyamide meets the above range, the viscosity of the nanospinning dope is suitable, thereby enabling the electrospinning process to proceed smoothly, forming non-beaded nanofiber membranes.

[0108] In the present application, during the electrospinning process, an additive can be selectively added. For example, without adding an additive, a continuous and uniform heterocyclic aramid nanofiber can be formed, but the heat resistance of the heterocyclic aramid nanofiber will decrease; adding a certain amount of additive will increase the conductivity of the spinning dope, thereby facilitating the smooth progress of electrospinning. However, when the amount of additive is too large, the conductivity of the spinning dope is too high, the movement time of the spinning jet in the electric field is shortened, and the solvent in the spinning dope cannot be fully evaporated, thereby resulting in a discontinuous and unstable electrospinning process, accompanied by the dripping of the spinning glue and the formation of beaded fibers, and the continuous and uniform nanofiber membrane cannot be smoothly prepared. Preferably, when the amount of additive meets the above defined range, the electrospinning property of thiophene polyamide is improved, which facilitates the smooth progress of electrospinning.

[0109] The fourth aspect of the present application provides a nanofiber membrane prepared by the method of the present application, wherein the tensile stress of the nanofiber membrane is ≥40 MPa, the tensile strain is ≥4%, the heat resistance temperature (T5%) is ≥350°C, and the antibacterial rate is ≥90%.

[0110] Preferably, the tensile stress of the nanofiber membrane is 40-90 MPa, the tensile strain is 4-30%, the heat resistance temperature (T5%) is 350-505°C, and the antibacterial rate is 94-96%.

[0111] The fifth aspect of the present application provides the application of the nanofiber membrane of the present application in water treatment, automobile fuel filter screen, new energy battery, automobile air conditioner filter screen, and medical protective supplies.

[0112] According to a particularly preferred embodiment of the present application, a method for preparing a nanofiber membrane is provided, which comprises the following steps:

[0113] (1) At room temperature, an organic solvent, thiophene polyamide solid, and an inorganic salt additive are added to a reaction bottle, mixed and stirred, and the product is completely dissolved, and the system is a uniform liquid, i.e. a nanospinning dope containing thiophene polyamide solid is obtained;

[0114] The amount of the thienyl polyamide is 5-15 wt% and the amount of the auxiliary is 0.1-5 wt% based on the mass of the organic solvent.

[0115] (2) The spinning dope is added to a syringe, and electrospinning is performed using a flat needle, with the electrospinning conditions being: voltage 6-10 kV, extrusion rate 2-2.4 mL / h, drawing air pressure 0.06-0.08 MPa, jet hole inner diameter 0.1-0.4 mm, and the fiber membrane sample being collected at a receiving distance of 18-20 cm to obtain a nanofiber membrane.

[0116] The application will be described in detail below through examples.

[0117] The test method for the inherent viscosity of the thienyl polyamide comprises the following steps: 1 g of the thienyl polyamide is placed in 25 mL of dimethylacetamide (DMAC), and the mass concentration of the prepared solution is denoted as c0 (g / mL); the foregoing solution is added to an Ubbelohde viscometer, and the outflow time of the solution flowing through the two scale lines of the viscometer is measured and denoted as t0 (min); DMAC is measured in the Ubbelohde viscometer, and the outflow time of DMAC flowing through the two scale lines of the viscometer is measured and denoted as t1 (min), and the inherent viscosity = In (t0 / t1) / c0.

[0118] The molar content of the structural unit represented by formula (I) in the thienyl polyamide is determined by nuclear magnetic resonance spectroscopy.

[0119] The nuclear magnetic resonance hydrogen spectrum analysis is determined by a nuclear magnetic resonance spectrometer.

[0120] In the following examples and comparative examples, the reagents are commercially available unless otherwise specified.

[0121] Preparation Example 1

[0122] (1) Nitrogen is continuously introduced into a reaction kettle, and 225 mL of N-methylpyrrolidone, 0.02 mol of butanediamine and 0.02 mol of dimethylthiophene dicarboxylate are sequentially added to the reaction kettle at room temperature, and heated to 120℃ for prepolymerization for 2 h;

[0123] (2) The reaction temperature is raised to 160℃, and 0.034 g of tetrabutyl titanate is further added, and the reaction is continued for 5 h to obtain a thienyl polyamide solution;

[0124] (3) The thienyl polyamide solution is cooled to 25℃, 450 mL of tetrahydrofuran is added, and stirring and suction filtration are performed, and the obtained filter cake is dried to obtain a thienyl polyamide solid A1 (inherent viscosity 1.03 dL / g, molar content of the structural unit represented by formula (I) 50%);

[0125] The thienyl polyamide solid A1 was subjected to hydrogen nuclear magnetic resonance spectrum analysis, and the nuclear magnetic resonance spectrum is shown in Figure 1 .

[0126] Preparation Example 2

[0127] (1) Nitrogen was continuously introduced into a reaction kettle, and 225 mL of N-methylpyrrolidone, 0.01 mol of 4,4-diaminodiphenyl ether, 0.01 mol of pentanediamine and 0.02 mol of dimethylthiophene dicarboxylate were sequentially added into the reaction kettle at room temperature, and the pre-polymerization was carried out by heating to 120°C for 2 h;

[0128] (2) The reaction temperature was raised to 160°C, and 0.034 g of tetrabutyl titanate was further added, and the reaction was continued for 5 h to obtain a thienyl polyamide solution;

[0129] (3) The thienyl polyamide solution was cooled to 25°C, 450 mL of tetrahydrofuran was added, and stirring, suction filtration and drying of the obtained filter cake were carried out to obtain a thienyl polyamide solid A2 (the specific viscosity was 1.51 dL / g, and the molar content of the structural unit represented by formula (I) was 50%).

[0130] Preparation Example 3

[0131] (1) Nitrogen was continuously introduced into a reaction kettle, and 225 mL of N-methylpyrrolidone, 0.02 mol of 4,4-diaminodiphenyl ether, 0.01 mol of dimethylthiophene dicarboxylate, 0.005 mol of dimethyl isophthalate and 0.005 mol of dimethyl pyridine dicarboxylate were sequentially added into the reaction kettle at room temperature, and the pre-polymerization was carried out by heating to 120°C for 2 h;

[0132] (2) The reaction temperature was raised to 160°C, and 0.034 g of tetrabutyl titanate was further added, and the reaction was continued for 5 h to obtain a thienyl polyamide solution;

[0133] (3) The thienyl polyamide solution was cooled to 25°C, 450 mL of tetrahydrofuran was added, and stirring, suction filtration and drying of the obtained filter cake were carried out to obtain a thienyl polyamide solid A3 (the specific viscosity was 2.25 dL / g, and the molar content of the structural unit represented by formula (I) was 25%).

[0134] Preparation Example 4

[0135] (1) Nitrogen was continuously introduced into a reaction kettle, and 225 mL of N-methylpyrrolidone, 0.02 mol of 2-(4-aminophenyl)-5-aminobenzimidazole, 0.01 mol of dimethylthiophene dicarboxylate and 0.01 mol of dimethyl pyrazine dicarboxylate were sequentially added into the reaction kettle at room temperature, and the pre-polymerization was carried out by heating to 120°C for 2 h;

[0136] (2) The reaction temperature was raised to 160°C, and 0.034 g of tetrabutyl titanate was further added, and the reaction was continued for 5 h to obtain a thiophene polyamide solution;

[0137] (3) The thiophene polyamide solution was cooled to 25°C, 450 mL of tetrahydrofuran was added, and stirring, suction filtration, and drying of the obtained filter cake were performed to obtain a thiophene polyamide solid A4 (the inherent viscosity was 2.33 dL / g, and the molar content of the structural unit represented by formula (I) was 25%).

[0138] Preparation Example 5

[0139] (1) Nitrogen was continuously introduced into a reaction vessel, and 225 mL of N-methylpyrrolidone, 0.02 mol of 4,4'-bis(3-aminophenoxy)diphenyl sulfone, 0.01 mol of dimethyl thiophene dicarboxylate, and 0.01 mol of dimethyl pyridine dicarboxylate were sequentially added to the reaction vessel at room temperature, and the reaction was heated to 120°C to perform a prepolymerization reaction for 2 h;

[0140] (2) The reaction temperature was raised to 160°C, and 0.034 g of tetrabutyl titanate was further added, and the reaction was continued for 5 h to obtain a thiophene polyamide solution;

[0141] (3) The thiophene polyamide solution was cooled to 25°C, 450 mL of tetrahydrofuran was added, and stirring, suction filtration, and drying of the obtained filter cake were performed to obtain a thiophene polyamide solid A5 (the inherent viscosity was 2.62 dL / g, and the molar content of the structural unit represented by formula (I) was 25%).

[0142] Preparation Example 6

[0143] (1) Nitrogen was continuously introduced into a reaction vessel, and 225 mL of N-methylpyrrolidone, 0.02 mol of 4,4'-bis(3-aminophenoxy)diphenyl sulfone, 0.01 mol of dimethyl thiophene dicarboxylate, and 0.01 mol of dimethyl pyridine dicarboxylate were sequentially added to the reaction vessel at room temperature, and the reaction was heated to 120°C to perform a prepolymerization reaction for 2 h;

[0144] (2) The reaction temperature was raised to 160°C, and 0.034 g of tetrabutyl titanate was further added, and the reaction was continued for 5 h to obtain a thiophene polyamide solution;

[0145] (3) The thiophene polyamide solution was cooled to 25°C, 450 mL of tetrahydrofuran was added, and stirring, suction filtration, and drying of the obtained filter cake were performed to obtain a thiophene polyamide solid A6 (the inherent viscosity was 2.18 dL / g, and the molar content of the structural unit represented by formula (I) was 33%).

[0146] Preparation Example 7

[0147] (1) continuously bubbled nitrogen into a reaction kettle, and then added 225 mL of N-methylpyrrolidone, 0.02 mol of 4,4-diaminodiphenyl ether, 0.01 mol of m-phenylenediamine, 0.01 mol of dimethylthiophene dicarboxylate and 0.02 mol of dimethyl pyridine dicarboxylate into the reaction kettle successively at room temperature, heated to 120°C for pre-polymerization for 2 h;

[0148] (2) the reaction temperature was raised to 160°C, and then 0.034 g of tetrabutyl titanate was added, and the reaction was continued for 5 h to obtain a thiophene polyamide solution;

[0149] (3) the thiophene polyamide solution was cooled to 25°C, 450 mL of tetrahydrofuran was added, stirred, suction filtered, and the obtained filter cake was dried to obtain a thiophene polyamide solid A7 (the specific viscosity logarithm was 2.46 dL / g, and the molar content of the structural unit represented by formula (I) was 16.6%).

[0150] Preparation Example 8

[0151] (1) continuously bubbled nitrogen into a reaction kettle, and then added 225 mL of N-methylpyrrolidone, 0.02 mol of 4,4-diaminodiphenyl ether, 0.02 mol of p-phenylenediamine, 0.075 mol of 2-(4-aminophenyl)-5-aminobenzimidazole, 0.105 mol of dimethylthiophene dicarboxylate, 0.005 mol of dimethyl terephthalate and 0.005 mol of dimethyl pyridine dicarboxylate into the reaction kettle successively at room temperature, heated to 120°C for pre-polymerization for 2 h;

[0152] (2) the reaction temperature was raised to 160°C, and then 0.034 g of tetrabutyl titanate was added, and the reaction was continued for 5 h to obtain a thiophene polyamide solution;

[0153] (3) the thiophene polyamide solution was cooled to 25°C, 450 mL of tetrahydrofuran was added, stirred, suction filtered, and the obtained filter cake was dried to obtain a thiophene polyamide solid A8 (the specific viscosity logarithm was 2.03 dL / g, and the molar content of the structural unit represented by formula (I) was 45.6%).

[0154] Preparation Example 9

[0155] (1) continuously bubbled nitrogen into a reaction kettle, and then added 225 mL of N-methylpyrrolidone, 0.02 mol of 4,4-diaminodiphenyl ether, 0.0075 mol of 2-(4-aminophenyl)-5-aminobenzimidazole, 0.0175 mol of dimethylthiophene dicarboxylate and 0.01 mol of dimethyl pyridine dicarboxylate into the reaction kettle successively at room temperature, heated to 120°C for pre-polymerization for 2 h;

[0156] (2) The reaction temperature was raised to 160°C, and 0.034 g of tetrabutyl titanate was added, and the reaction was continued for 5 h to obtain a thienyl polyamide solution;

[0157] (3) The thienyl polyamide solution was cooled to 25°C, 450 mL of tetrahydrofuran was added, and stirring, suction filtration, and drying of the obtained filter cake were carried out to obtain thienyl polyamide solid A9 (the specific viscosity was 2.76 dL / g, and the molar content of the structural unit represented by formula (I) was 31.8%).

[0158] Example 1

[0159] (1) 100 g of N-methylpyrrolidone, 5 g of thienyl polyamide solid Al (Preparation Example 1), and 0.7 g of boehmite were added to a reaction bottle at room temperature, and stirring was continued until the product was completely dissolved, and the system became a homogeneous liquid to obtain a nanospinning dope containing thienyl polyamide solid Al;

[0160] (2) The spinning dope was added to a syringe with a diameter of 12 mm, and electrospinning was carried out using a flat needle with a diameter of 25G under the following conditions: voltage 8 kV, extrusion rate 2.4 mL / h, stretching air pressure 0.08 MPa, and jet hole inner diameter 0.4 mm, and a fiber membrane sample was collected at a receiving distance of 20 cm to obtain nanofiber membrane Bl (the finished product of nanofiber membrane Bl is shown in FIG. 1). Figure 2

[0161] Examples 2 to 9

[0162] The method of Example 1 was followed, except that thienyl polyamide solid Al was replaced by thienyl polyamide solids A2 to A9 (Preparation Examples 2 to 9) to obtain nanofiber membranes B2 to B9, respectively.

[0163] Example 10

[0164] The method of Example 1 was followed, except that no additive was added, to obtain nanofiber membrane B10.

[0165] In this example, the thienyl polyamide was successfully electrospun without the additive, and continuous and uniform nanofibers were obtained, but the heat resistance of the nanofiber membrane was decreased.

[0166] Comparative Example 1

[0167] The method of Example 1 was followed, except that the amount of the additive was 10 g, to obtain nanofiber membrane Cl.

[0168] ​When the dosage of the auxiliary agent is too much, the conductivity of the nanospinning dope is too high, the movement time of the spinning jet in the electric field is shortened, the spinning solvent cannot be fully evaporated, the electrospinning process is discontinuous and unstable, accompanied by dripping of the spinning glue, and further leading to the formation of beaded fibers, and continuous and uniform nanofibers cannot be successfully prepared.

[0169] Comparative Example 2

[0170] According to the method of Example 10, except that the thienyl polyamide solid A1 was replaced by meta-aramid to obtain nanofiber membrane C2;

[0171] The electrospinning process is discontinuous and unstable, and the phenomenon of dripping of the spinning dope occurs from time to time, and continuous and uniform nanofibers cannot be successfully prepared.

[0172] Comparative Example 3

[0173] According to the method of Example 1, except that the thienyl polyamide solid A1 was replaced by meta-aramid to obtain nanofiber membrane C3;

[0174] The electrospinning process is discontinuous and unstable, and the phenomenon of dripping of the nanospinning dope occurs from time to time, and continuous and uniform nanofibers cannot be successfully prepared, and the fibers are beaded.

[0175] Test Example 1

[0176] The nanofiber membranes B3 and B9 in Examples 3 and 9 were respectively subjected to thermogravimetric analysis (TGA test), and the results are shown in Table 1. Figures 3-4

[0177] The TGA test was determined by the method of GB / T 17050-1997 Thermal Radiometry Terms.

[0178] Test Example 2

[0179] The nanofiber membrane B2 in Example 2 was subjected to SEM scanning, and the results are shown in Table 2. Figure 5

[0180] The SEM scanning electron microscope was determined by the method of GB / T 17359-1998 Electron Probe and Scanning Electron Microscope X-ray Energy Spectrum Quantitative Analysis General Rules.

[0181] Test Example 3

[0182] The nanofiber membrane B3 in Example 3 was subjected to DMA tensile strength test, and the results are shown in Table 3. Figure 6

[0183] The DMA tensile strength test was performed by the method of GB / T 528-2009 Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber.​​​

[0184] Test Example 4

[0185] The nanofiber membranes B1-B10 and C3 prepared in Examples 1-10 and Comparative Example 3 were respectively subjected to mechanical property, heat resistance and hydrophobicity tests, and the results are shown in Table 1.

[0186] The mechanical property was tested according to GB / T 14344-2022 Chemical fiber filament tensile property test method.

[0187] The heat resistance was tested by thermogravimetric analysis (TGA) method.

[0188] The hydrophobicity was tested by GB / T 20058-2017 Rolling bearing single row angular contact ball outer ring non-thrust end chamfer dimension method.

[0189] Test Example 5

[0190] The nanofiber membrane B4 prepared in Example 4 was subjected to antibacterial property test, and the results are shown in Table 2.

[0191] The antibacterial property was tested by GB / T 20944.3-2008 Textiles-Evaluation of antibacterial properties of textiles-Part 3: Shake flask method.

[0192] Table 1

[0193]

[0194]

[0195] Table 2

[0196]

[0197] Figure 1 The nuclear magnetic resonance spectrum of the thiophene polyamide solid A1 prepared in Preparation Example 1 of the present application is shown in Figure 1. Figure 1 It can be seen that the nuclear magnetic resonance test data of the thiophene polyamide solid A1 are as follows: 1 HNMR (400 MHz, CDCl3) δ 7.72 (s, 2H), 3.64 (m, 4H), 1.85 (m, 4H). It can be seen that the thiophene polyamide solid A1 prepared in Example 1 of the present application contains a thiophene group.

[0198] Figure 2 The finished product diagram of the nanofiber membrane B1 in Example 1 of the present application is shown in Figure 2. Figure 2 It can be seen that the nanofiber membrane B1 has a continuous and complete appearance.

[0199] Figure 3 and Figure 4TGA graphs of nanofiber membranes B3 and B9 in Example 3 and Example 9, respectively. From the TGA graphs, it can be seen that the T5% decomposition temperatures of B3 and B9 are as high as 452℃ and 505℃, respectively, which indicates that the nanofiber membranes B3 and B9 have high heat resistance. Figures 3-4

[0200] Figure 5 SEM scanning graph of nanofiber membrane B2 in Example 2. From the SEM scanning graph, it can be seen that the nanofiber membrane B2 has a diameter controlled in the range of 100-300nm and a uniform morphology. Figure 5

[0201] Figure 6 DMA tensile curve graph of nanofiber membrane B3 in Example 3. From the DMA tensile curve graph, it can be seen that the nanofiber membrane B3 has strong toughness and high modulus characteristics. Figure 6

[0202] From the data in Table 1, it can be seen that the nanofiber membranes prepared by the methods of Examples 1-9 of the present application have excellent mechanical strength, thermal stability and hydrophobicity. In Example 10, a continuous and uniform heterocyclic aramid nanofiber can be formed in the electrospinning process without adding an auxiliary agent, but the heat resistance of the heterocyclic aramid nanofiber decreases, which may be because the electrical conductivity of the thiophene polyamide is high, which increases the electrical conductivity of the spinning dope, thereby facilitating the smooth progress of electrospinning, indicating that the thiophene polyamide has better processability. In Comparative Example 3, the nanofiber is prepared by using meta-aramid as a raw material, and the electrospinning process is discontinuous and unstable, and the phenomenon of nanospinning dope dripping occurs from time to time, and the fiber membrane presents a string of beads, which cannot smoothly prepare a continuous and uniform nanofiber membrane, and the mechanical properties and heat resistance of the prepared nanofiber membrane are both poor. Therefore, it can be seen that the thiophene polyamide is more easily electrospun than the traditional meta-aramid, and the mechanical properties and heat resistance of the prepared nanofiber membrane are more excellent.

[0203] From the data in Table 2, it can be seen that the nanofiber membrane prepared by using the thiophene polyamide of the present application as a raw material has excellent antibacterial properties.

[0204] In summary, the nanofiber membrane prepared by using the thiophene polyamide of the present application has high mechanical strength, strong heat resistance, strong hydrophobicity and antibacterial properties, and can be used for a long time under high temperature working conditions, and has a broad application prospect in the fields of water treatment, automobile fuel filter screen, new energy battery, automobile air conditioner filter screen, medical protective products and the like.

[0205] ​​​The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including that each technical feature is combined in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A thiophene polyamide characterized by, The thiophene polyamide contains the structural unit shown in formula (I); X and Y are each independently selected from hydrogen, alkyl, halogen, amino, and amino derivatives.

2. The thiophene polyamide of claim 1, wherein, Based on the total amount of the thiophene polyamide, the molar content of the structural unit represented by formula (I) in the thiophene polyamide is 5-80 mol%. And / or, the thiophene polyamide has a specific logarithmic viscosity of 1.03-2.76 dL / g, preferably 1.55-2.76 dL / g.

3. A process for the preparation of a thienyl polyamide, characterized in that, The method includes the following steps: (1) In the presence of an inert gas and an organic solvent A, a prepolymerization reaction is carried out between a diamine monomer and a diformate monomer. (2) Add a catalyst to carry out a polycondensation reaction to obtain thiophene polyamide; The dicarboxylate monomer is selected from dicarboxylate compounds containing thiophene groups.

4. The method of claim 1, wherein, The organic solvent A is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, dichloroethane, N,N-dimethylacetamide, and N-methylpyrrolidone; And / or, the catalyst is selected from at least one of tetrabutyl titanate, dioctyltin dilaurate and isopropyltris(dodecylbenzenesulfonyl)titanate, preferably tetrabutyl titanate; And / or, the conditions for the prepolymerization reaction include: a temperature of 100-120°C and a time of 1-3 hours; And / or, the conditions for the polycondensation reaction include: a temperature of 160-180°C and a time of 3-5 hours.

5. The method of claim 3 or 4, wherein, The molar ratio of the dimethyl ester monomer to the diamine monomer is (0.95-1.05):1; Preferably, the dimethyl thiophene dimethyl ester monomer is selected from dimethyl thiophene dimethyl ester monomer or a mixture of dimethyl thiophene dimethyl ester and compound B; Preferably, compound B is selected from aromatic dimethyl dicarboxylate and / or heterocyclic dimethyl dicarboxylate; Preferably, the molar amount of the dimethyl thiophene dicarboxylate monomer is 3%-90% of the total molar amount of the dicarboxylate monomer and the diamine monomer; And / or, the mass ratio of the organic solvent A to the sum of the diformate monomer and the diamine monomer is (3-10):1, preferably (5-7):1; And / or, the molar ratio of the catalyst to the dicarboxylate monomer is (0.001-0.05):

1.

6. The method of any of claims 3-5, wherein, The aromatic dimethyl dicarboxylate is selected from at least one of dimethyl isophthalate, dimethyl terephthalate, dimethyl naphthalate, and dimethyl 1,3,5-benzenetricarboxylate. And / or, the heterocyclic dimethyl dicarboxylate is selected from at least one of dimethyl pyridine dicarboxylate, dimethyl pyrazine dicarboxylate, and dimethyl pyrimidine dicarboxylate; And / or, the diamine monomer is selected from at least one of phenyl diamines, aliphatic diamines, and heterocyclic diamines; Preferably, the phenyl diamine is selected from at least one of 4,4'-(1,4-phenyldioxy)bisphenylamine, 2,2'-dimethyl-4,4'-diaminobiphenyl, m-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, naphthyldiamine, and p-phenylenediamine, more preferably m-phenylenediamine and / or p-phenylenediamine; Preferably, the aliphatic diamine is selected from at least one of ethylenediamine, propylenediamine, butanediamine, pentanediamine, hexanediamine, and nonanediamine, more preferably butanediamine and / or pentanediamine; Preferably, the heterocyclic diamine is at least one selected from 2-(4-aminophenyl)-5-aminobenzoxazole, 2-(4-aminophenyl)-5-aminobenzimidazole, 3,4-diaminodiphenyl ether, 3,3-diaminodiphenyl sulfone, 4,4-diaminodiphenyl sulfone, 4,4'-bis(3-aminophenoxy)diphenyl sulfone, 4,4-diaminodiphenyl ether, 2,2'-bis(trifluoromethyl)diaminobiphenyl, and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, more preferably at least one of 4,4-diaminodiphenyl ether, 2-(4-aminophenyl)-5-aminobenzimidazole, and 4,4'-bis(3-aminophenoxy)diphenyl sulfone.

7. A method for producing a nanofiber membrane, characterized by, The method comprises the following steps: (1) adding thiophene polyamide and optional auxiliary in an organic solvent C, mixing and stirring to obtain a nanospinning stock solution; (2) electrospinning treatment of the nanospinning stock solution to obtain a nanofiber membrane.

8. The method of claim 7, wherein, The electrospinning treatment conditions include: voltage of 6-10 kV, extrusion rate of 2-2.4 mL / h, stretching wind pressure of 0.06-0.08 MPa, spinneret inner diameter of 0.1-0.4 mm, and receiving distance of 18-20 cm; Preferably, the average diameter of the nanofibers in the nanofiber membrane is 100-350 nm.

9. The method of claim 7 or 8, wherein, The organic solvent C is at least one selected from N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, dichloromethane, chloroform, ethanol, methanol, n-pentane, and n-butane; and / or, the auxiliary is at least one selected from lithium chloride, calcium chloride, lithium bromide, calcium bromide, boehmite, silicon dioxide, aluminum oxide, zirconium oxide, polyethylene glycol, and polyethylene glycol ether; Preferably, the amount of the thiophene polyamide is 1-15 wt% and the amount of the auxiliary is 0.05-5 wt% based on the mass of the organic solvent C.

10. A nanofiber membrane produced by the method of any one of claims 7-9, wherein, wherein, The tensile stress of the nanofiber membrane is ≥40 MPa, the tensile strain is ≥4%, the heat resistance temperature (T5%) is ≥350℃, and the antibacterial rate is ≥90%; Preferably, the tensile stress of the nanofiber membrane is 40-90 MPa, the tensile strain is 4-30%, the heat resistance temperature (T5%) is 350-505℃, and the antibacterial rate is 94-96%.

11. Application of the nanofiber membrane of claim 10 in water treatment, automobile fuel filter screen, new energy battery, automobile air conditioner filter screen, and medical protective supplies.

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