Polyamidoxime neutral solution as well as preparation method and application thereof

Abstract

The invention provides a polyamidoxime neutral solution as well as a preparation method and application thereof, and relates to the technical field of high polymer material processing. The preparation method of the polyamidoxime neutral solution comprises the following steps: S1, pre-dissolving polyamidoxime, namely weighing polyamidoxime, putting the weighed polyamidoxime into an alkaline aqueous solution of sodium hydroxide, and completely dissolving the weighed polyamidoxime to obtain a pre-dissolving pre-solution; s2, co-solvent blending: weighing a co-solvent, adding the co-solvent into the pre-dissolving preposed solution, and completely dissolving the co-solvent to obtain a preposed solution; s3, regulating and controlling the pH value of the solution, namely adding a pH regulator for multiple times, and uniformly mixing until the pH value of the solution is neutral, so as to obtain the neutral polyamidoxime solution. The polyamidoxime neutral solution does not depend on an alkaline solvent system, the material stability is improved, the processing adaptability and the structural design freedom degree of polyamidoxime can be effectively improved, the polyamidoxime neutral solution is suitable for multiple processing modes in a neutral environment, and the application field of polyamidoxime is expanded.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer material processing, and particularly relates to a polyamidoxime neutral solution and a preparation method and application thereof. BACKGROUND

[0002] Efficient adsorption and enrichment of uranyl ions (UO2²⁺) is an important research direction in the fields of nuclear fuel recovery, environmental governance, and uranium extraction from seawater. In recent years, amidoxime functional groups have attracted widespread attention due to their excellent coordination ability for uranyl ions. Polymers based on such functional groups, especially polyamidoxime, have become one of the cores of adsorption materials for uranium extraction from seawater. However, due to the presence of rigid structures, strong polar side groups, and multiple hydrogen bonding in the main chain of polyamidoxime molecules, they exhibit poor solubility in conventional neutral or weakly acidic solvents, which severely limits their application in solution processing, interfacial modification, film formation, and composite material preparation. To solve this problem, existing technologies generally use alkaline aqueous solutions (such as NaOH, KOH, etc.) or add ammonia ligands to assist in dissolving polyamidoxime. For example, some research reports that partial solubility of polyamidoxime can be achieved in 0.1-0.5 mol / L NaOH solution, and then freeze-drying or impregnation coating is used to prepare materials. For example, the prior art CN117085654A discloses a preparation method of a high-efficiency uranium extraction loaded polyamidoxime biochar ball adsorbent material, which uses an alkaline polyamidoxime solution obtained by completely dissolving polyamidoxime powder in a sodium hydroxide solution, and then adding glutaraldehyde and biochar balls to obtain a biochar ball adsorbent loaded with polyamidoxime. The alkaline polyamidoxime solution is still used for subsequent material preparation. Such a scheme has the following main problems: 1. Alkaline environment limits material stability: strong alkaline conditions may cause main chain degradation, functional group hydrolysis, or cross-linking side reactions, affecting the structural integrity and adsorption performance of the final material. 2. Poor process compatibility: alkaline processing requires high corrosion resistance of equipment, and is difficult to be compatible with various neutral or acidic sensitive components, limiting the blending or compounding of polyamidoxime with other functional materials. 3. Difficult to further process: the existing alkaline processing method is not suitable for systems containing acidic components, hindering the structural design and performance integration of polyamidoxime in multifunctional composite materials (such as difficult to dope or double network polymerization under neutral or acidic conditions).

[0003] Therefore, developing a new method for realizing the dissolution and processing of polyamidoxime under neutral conditions is of great significance for expanding its processing methods, improving the stability of the material, and promoting its application in multi-scene adsorption systems. However, so far there is no public report on a process method that can effectively dissolve polyamidoxime in a neutral environment, and new technical breakthroughs are urgently needed in this field. SUMMARY

[0004] The present application aims at the defects and deficiencies in the prior art that poly-amino-oxime materials can only be dissolved in alkaline conditions and are difficult to realize solution processing, functional doping or structural synergistic construction in neutral or acidic environment, and provides a preparation method of poly-amino-oxime neutral solution, which can dissolve and process poly-amino-oxime in neutral conditions without relying on alkaline solvent system, can effectively improve the processing adaptability and structural design freedom of poly-amino-oxime, is suitable for various processing modes such as film forming, compounding, crosslinking or double network construction in neutral environment, and thus expands the application in the fields of seawater uranium extraction, high-selectivity adsorption, environmental governance and the like.

[0005] Another object of the present application is to provide a poly-amino-oxime neutral solution.

[0006] Still another object of the present application is to provide an application of the poly-amino-oxime neutral solution in the preparation of poly-amino-oxime materials.

[0007] Still another object of the present application is to provide a poly-amino-oxime material prepared in a poly-amino-oxime neutral solution reaction system.

[0008] In a first aspect, the present application provides a preparation method of a poly-amino-oxime neutral solution, comprising the following steps: S1. Poly-amino-oxime pre-dissolution: poly-amino-oxime is placed into an alkaline aqueous solution to be completely dissolved to obtain a pre-dissolution solution, wherein the concentration of alkali in the alkaline aqueous solution is 0.1-0.15 mol / L, and the concentration of poly-amino-oxime in the pre-dissolution solution is 0.05-0.2 g / mL; S2. Co-blending of a cosolvent: the cosolvent is added to the pre-dissolution solution to be completely dissolved to obtain a pre-dissolution solution, wherein the cosolvent is one or more of formamide, urea and guanidine hydrochloride, and the addition amount is 0.05-0.5 g / mL; S3. pH adjustment of the solution: a pH adjuster is added to the pre-dissolution solution to be uniformly mixed until the pH value of the pre-dissolution solution is neutral to obtain a poly-amino-oxime neutral solution, wherein the pH adjuster is an acidic aqueous solution with a concentration of 1-5 mol / L.

[0009] According to the preparation method of the poly-amino-oxime neutral solution provided by the present application, preferably, the pH adjuster is added in multiple times in S3, and the single addition amount of the pH adjuster is 0.25-0.5 mL / mL of the pre-dissolution solution.

[0010] According to the preparation method of the poly-amino-oxime neutral solution provided by the present application, preferably, the dissolution temperature in S1 is 30-45℃.

[0011] According to the preparation method of the poly-amino-oxime neutral solution provided by the present application, preferably, the cosolvent in S2 is urea.

[0012] According to the poly-amidoxime neutral solution preparation method provided by the application, preferably, the adding amount of the cosolvent in S2 is 0.3-0.4 g / mL.

[0013] According to the poly-amidoxime neutral solution preparation method provided by the application, preferably, the pH regulator in S3 is hydrochloric acid solution, the concentration is 1-3 mol / L, and the single adding amount is 0.25 mL / mL pre-solution.

[0014] In the second aspect, the application further provides a poly-amidoxime neutral solution prepared by the poly-amidoxime neutral solution preparation method.

[0015] In the third aspect, the application further provides application of the poly-amidoxime neutral solution in preparation of a poly-amidoxime material.

[0016] According to the application of the poly-amidoxime neutral solution in preparation of a poly-amidoxime material, preferably, the poly-amidoxime material preparation process comprises any one of mixing, film forming, injection molding, printing, electrospinning, compounding and crosslinking.

[0017] In the fourth aspect, the application further provides a poly-amidoxime material prepared in a poly-amidoxime neutral solution reaction system.

[0018] Advantages: The poly-amidoxime neutral solution preparation method provided by the application has at least the following advantages over the existing poly-amidoxime alkaline solution system: (1) Avoiding alkaline degradation and improving material stability: The poly-amidoxime neutral solution preparation method of the application does not require long-term treatment of the alkaline cosolvent system, avoids the main chain rupture, functional group hydrolysis or crosslinking side reaction caused by the high pH environment, and significantly improves the structural integrity and adsorption activity retention rate of the poly-amidoxime material.

[0019] (2) Improving processing compatibility and process expandability: The solution system under neutral conditions of the application can be compatible with various pH-sensitive functional materials and components, facilitating the blending, compounding or covalent crosslinking of poly-amidoxime with various polymers, inorganic nanomaterials and the like, and significantly expanding the application range of the poly-amidoxime in functional thin films, gels, composite materials and the like.

[0020] (3) Realizing the construction of multiple structures: The poly-amidoxime neutral solution preparation method of the application is suitable for double-network polymerization, functional doping, in-situ film forming and other structure design strategies, provides a highly adaptive platform for constructing multifunctional integrated adsorption systems, and improves the mechanical strength, adsorption capacity and response performance of the material.

[0021] (4) The preparation method is mild and efficient, and is suitable for industrial scale-up: the preparation method of the application has mild operation conditions, a stable system, and no need for special equipment, and has good controllability and repeatability, and is suitable for large-scale continuous preparation, thereby providing a feasible technical path for industrial application of related adsorption materials. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to make the content of the application more easily understood, the application will be further described in detail below according to specific embodiments of the application and in conjunction with the drawings.

[0023] Figure 1 The infrared spectrum of the polyamidoxime used in the application.

[0024] Figure 2 The dissolution state diagram of the polyamidoxime in the polyamidoxime neutral solution of Example 1.

[0025] Figure 3 The macroscopic morphology diagram of the double-network hydrogel prepared in Example 2.

[0026] Figure 4 The macroscopic morphology diagram of the alkali-sensitive nanomaterial-doped hydrogel material prepared in Example 3.

[0027] Figure 5 The dissolution state diagram of the polyamidoxime in the polyamidoxime neutral solution of Example 4.

[0028] Figure 6 The macroscopic morphology diagram of the alkali-sensitive nanomaterial-doped hydrogel material prepared in Example 5.

[0029] Figure 7 The microscopic structure diagram of the alkali-sensitive nanomaterial-doped hydrogel material prepared in Example 5.

[0030] Figure 8 The dissolution state diagram of the polyamidoxime solution of Comparative Example 1.

[0031] Figure 9 The gelation situation diagram of the double-network hydrogel prepared in Comparative Example 4. DETAILED DESCRIPTION

[0032] The following examples are used to illustrate the application, but are not used to limit the scope of the application. If the specific techniques or conditions are not indicated in the examples, the techniques or conditions described in the literature in the art, or according to the product instructions are used. If the reagents or instruments are not indicated by the manufacturer, they are all conventional products that can be purchased through a regular channel.

[0033] In the detailed description, the application provides a preparation method of a polyamidoxime neutral solution, comprising the following steps: S1. Poly-amidoxime pre-dissolution: Put the poly-amidoxime into an alkaline aqueous solution to dissolve completely to obtain a pre-dissolution solution, wherein the concentration of the alkali in the alkaline aqueous solution is 0.1-0.15 mol / L, and the concentration of the poly-amidoxime in the pre-dissolution solution is 0.05-0.2 g / mL; S2. Co-solvent blending: Add a co-solvent into the pre-dissolution solution to dissolve completely to obtain a pre-solution, wherein the co-solvent is one or more of formamide, urea, guanidine hydrochloride, and the addition amount is 0.05-0.5 g / mL; S3. Solution pH adjustment: Add a pH adjuster into the pre-solution to mix uniformly until the pH value of the pre-solution is neutral to obtain a poly-amidoxime neutral solution, wherein the pH adjuster is an acidic aqueous solution with a concentration of 1-5 mol / L.

[0034] It should be noted that: In the preparation method of the poly-amidoxime neutral solution of the present application, the poly-amidoxime is first pre-dissolved in an alkaline aqueous solution to obtain a pre-dissolution solution with a specific poly-amidoxime concentration, and then a co-solvent is added to break the interaction between the poly-amidoxime molecules, so as to avoid the enhancement of the interaction between the poly-amidoxime molecular chains when the pH value of the pre-solution is adjusted to neutral in the next step, which leads to the formation of agglomeration and the failure to obtain a uniformly dissolved poly-amidoxime neutral solution, and further the failure to carry out further processing and modification of the poly-amidoxime under non-alkaline conditions.

[0035] The co-solvent mentioned in the present application can be selected as one or more of formamide, urea, and guanidine hydrochloride, wherein the formamide can change the solvent polarity, the urea can competitively destroy the hydrogen bond, and the guanidine hydrochloride can destroy the ionic bond, and the interaction between the poly-amidoxime molecules is broken by utilizing the effects of the co-solvent. The addition amount of the co-solvent is also a key control, which can be adjusted by the concentration of the poly-amidoxime. If the addition amount of the co-solvent is too low, the corresponding solubilization effect cannot be achieved, and if the addition amount is too high, the solution viscosity becomes large or the molecules are precipitated, and a uniformly stable pre-solution cannot be obtained.

[0036] In specific embodiments, the alkaline aqueous solution mentioned in S1 of the present application can be, for example, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, etc. In specific embodiments, the pH adjuster acidic aqueous solution mentioned in S3 of the present application can be, for example, an inorganic acid nitric acid aqueous solution, a hydrochloric acid aqueous solution, etc., or an organic acid, such as an acetic acid aqueous solution, etc.

[0037] In specific embodiments, in order to limit the local pH change fluctuation of the solution and avoid the precipitation of the polymer due to the excessively high acid concentration in some areas, a more uniform and stable poly-amidoxime neutral solution is obtained, and it is preferred that the addition of the pH adjuster in S3 is carried out in multiple times, and the single addition amount of the pH adjuster is 0.25-0.5 mL / mL of the pre-solution.

[0038] Further, the step of adding the pH regulator in S3 of the present application is preferably followed by stirring the pre-solution to a clear state before the next addition of the pH regulator in the specific embodiments, which can further avoid the aggregation and precipitation of the poly-amidoxime due to the too fast local pH change.

[0039] The present application provides a method for realizing efficient dissolution and solution processing of poly-amidoxime under neutral conditions, which does not require long-term treatment of an alkaline auxiliary solvent system, avoids the main chain rupture, functional group hydrolysis or cross-linking side reactions that may be caused by high pH environment, and significantly improves the structural integrity and adsorption activity retention rate of the poly-amidoxime material.

[0040] Moreover, the neutral solution of the poly-amidoxime prepared by the present application can be compatible with a variety of pH-sensitive functional materials and components under a neutral solution system, which facilitates the blending, compounding or covalent cross-linking of the poly-amidoxime with a variety of polymers, inorganic nanomaterials, etc., and significantly expands the application range of the poly-amidoxime in functional films, gels, composite materials, etc.

[0041] The dissolution process of the present application is mild and efficient, the system is stable, no special equipment is required, and it has good controllability and repeatability, which is suitable for large-scale continuous preparation and provides a feasible technical path for the industrial application of related adsorption materials.

[0042] In some specific embodiments, the concentration of the poly-amidoxime in the pre-solution in S1 of the present application can be, for example, 0.05 g / mL, 0.08 g / mL, 0.10 g / mL, 0.12 g / mL, 0.15 g / mL, 0.18 g / mL, 0.20 g / mL, etc., or any range value formed by the above point values, preferably 0.05-0.15 g / mL, and more preferably 0.1 g / mL.

[0043] In some specific embodiments, the step of weighing the poly-amidoxime powder and placing it in the alkaline aqueous solution for complete dissolution in S1 of the present application can be performed by heating to achieve better dissolution effect, and the dissolution temperature is preferably 30-45°C. The stirring and heating can also be used to further optimize the dissolution effect, and the stirring time is 10-30 min.

[0044] In other specific embodiments, the auxiliary solvent in S2 of the present application is preferably urea. Urea can competitively destroy hydrogen bonds, which is more conducive to destroying the interaction between poly-amidoxime molecules, weakening the interaction between the molecular chains of poly-amidoxime when the pH value of the system is adjusted to neutral, and avoiding aggregation, so as to finally obtain a uniformly dissolved poly-amidoxime neutral solution.

[0045] In other specific embodiments, the amount of the co-solvent added mentioned in S2 of the present invention can be, for example, 0.05 g / mL, 0.10 g / mL, 0.15 g / mL, 0.20 g / mL, 0.25 g / mL, 0.30 g / mL, 0.35 g / mL, 0.40 g / mL, 0.45 g / mL, 0.50 g / mL or any range value thereof, preferably 0.30~0.40 g / mL.

[0046] In other specific embodiments, the pH regulator mentioned in S3 of the present invention is a hydrochloric acid solution, and the concentration can be, for example, 1 mol / L, 3 mol / L, 5 mol / L, etc., and the single addition amount is 0.25 mL / mL pre-solution, 0.28 mL / mL pre-solution, 0.30 mL / mL pre-solution, 0.35 mL / mL pre-solution, 0.40 mL / mL pre-solution, 0.45 mL / mL pre-solution, 0.50 mL / mL pre-solution, etc., or any range value thereof.

[0047] In some specific embodiments, the present invention also provides a method for preparing a neutral solution of polyamidooxime and a neutral solution of polyamidooxime prepared therefrom.

[0048] The polyamidooxime neutral solution of the present invention is a neutral solution and can be widely used in the preparation of polyamidooxime materials.

[0049] In some specific embodiments, the preparation process of the polyamidoxime material mentioned in the present invention may include any one of mixing, film forming, injection molding, printing, electrospinning, compounding, and cross-linking.

[0050] The neutral solution of polyamidooxime provided by the present invention can fully dissolve polyamidooxime under neutral conditions, thereby providing the possibility for further processing of polyamidooxime, effectively improving the processing adaptability and structural design freedom of polyamidooxime, and is suitable for realizing polyamidooxime solution processing, functional composite and material molding under neutral conditions. It can be widely used in the technical fields related to functional polymer adsorption materials, seawater uranium extraction materials and their preparation processes, and improves the mechanical strength, adsorption capacity and response performance of the material.

[0051] In a specific embodiment, the present invention also provides a polyamidoxime material prepared in a polyamidoxime neutral solution reaction system.

[0052] In some embodiments, for example, a free radical photoinitiator can be introduced into the neutral polyamidoxime solution system provided by the present invention, enabling in-situ photocuring under ultraviolet or visible light to form a hydrogel material with a three-dimensional network structure. This method is suitable for applications such as controlled molding, microstructure processing, and flexible material preparation.

[0053] For example, the neutral solution system provided by the present application has good process compatibility and is suitable for synergistic doping or compounding with conductive polymers (such as polypyrrole, PEDOT, etc.), carbon nanomaterials (diamond powder, graphene) or metal oxide nanoparticles (such as TiO2, Fe3O4), so as to construct multifunctional materials with electrical responsiveness, magnetic responsiveness or enhanced mechanical properties.

[0054] For example, in the field of environmental governance, in addition to uranyl ions, the polyamidoxime and its derivative materials prepared by the present application can also be used for efficient adsorption and separation of other heavy metal ions (such as Pb2+, Cd2+, Hg2+, Cu2+ and the like) in solution, and have good popularization prospects in the fields of industrial wastewater treatment, environmental remediation, precious metal recovery and the like Embodiment 1 A preparation method of a polyamidoxime neutral solution, comprising the following steps: S1. Polyamidoxime pre-dissolution: 0.1 g of polyamidoxime powder is dissolved in 1 mL of 0.12 mol / L sodium hydroxide solution, and stirred at 30°C and 600 rpm until completely dissolved to obtain a pre-dissolution solution, and the concentration of polyamidoxime in the pre-dissolution solution is 0.1 g / mL; S2. Solubilizer blending: after the pre-dissolution solution is cooled to room temperature, a solubilizer is added and dissolved completely to obtain a pre-solution, wherein the addition amount of the solubilizer is 0.3 g / mL, and the solubilizer is urea; S3. Solution pH adjustment: a pH adjusting agent is added to the pre-solution in multiple times and mixed uniformly, and the pH of the pre-solution is adjusted to about 7 to obtain a polyamidoxime neutral solution, wherein the pH adjusting agent is a 3 mol / L hydrochloric acid solution, and the single addition amount is 0.25 mL.

[0055] wherein, Figure 1 is the infrared spectrum of the polyamidoxime used in the present application. At present, there is no commercially available product of polyamidoxime molecule, and the polyamidoxime used in the present patent is obtained by modification of polyacrylonitrile, and the molecular structure change is as follows Figure 1 The infrared spectrum of the polyamidoxime material used in the method should meet the requirements shown in Figure 1 .

[0056] wherein, the polyamidoxime is obtained by modification of polyacrylonitrile, and the specific modification preparation method is as follows: (1) 45 mL of DMF (N,N-dimethylformamide) and 8.24 g of hydroxylamine hydrochloride are stirred and dissolved at 45°C, then 5.74 g of sodium carbonate and 1.44 g of sodium hydroxide are added, stirred for 3 h, then 3.18 g of PAN (polyacrylonitrile) is added and stirred for 30 min until dissolved, and then stirred at 65°C for 24 h; (2) The reaction product of step (1) is added with 2.86 g of sodium carbonate and 0.72 g of sodium hydroxide, and kept stirring at 65°C for 24 hours. The reaction completed solution is centrifuged at a speed of 10000 rpm for 20 min. The supernatant after centrifugation is added dropwise into deionized water for precipitation. The polymer obtained by precipitation is poly-glyoxime, which is dried at 55°C under vacuum for use.

[0057] (Reference technology, literature DOI number: 10.1002 / adma.201906615) Figure 2 The solubility state diagram of poly-glyoxime in the poly-glyoxime neutral solution can be seen from Figure 2 It can be seen that when the pH of the solution is neutral, the polymer solution can still maintain a clear and transparent state, and no obvious polymer precipitation occurs.

[0058] Example 2 A preparation method of a double-network hydrogel material, comprising the following steps: The poly-glyoxime neutral solution prepared in Example 1 is stirred at a speed of 800 rpm for 2 h. 120 mg of acrylamide, 10 mg of N,N'-methylenebisacrylamide, and 1 mg of azobisdimethylaminoformamide hydrochloride are added. After stirring for 30 min, polymerization is initiated under ultraviolet light for 10 min to obtain a gel material as shown in FIG. 2. The macroscopic morphology of the gel is good. Figure 3

[0059] Example 3 A preparation method of a base-sensitive nanomaterial-doped hydrogel material, comprising the following steps: The poly-glyoxime neutral solution prepared in Example 1 is stirred at a speed of 800 rpm for 2 h. 2 mg of base-sensitive COF nanomaterial is added to the solution. The mixed solution is stirred at a speed of 800 rpm for 4 h. Then 240 mg of acrylamide, 20 mg of N,N'-methylenebisacrylamide, and 2 mg of azobisdimethylaminoformamide hydrochloride are added to the mixed solution. After stirring for 30 min, polymerization is initiated under ultraviolet light for 10 min to obtain a doped gel material as shown in FIG. 3. The macroscopic morphology of the gel is good. Figure 4

[0060] Example 4 A preparation method of a poly-glyoxime neutral solution, comprising the following steps: S1. Pre-dissolution of poly-glyoxime: 0.2 g of poly-glyoxime powder is dissolved in 2 mL of 0.15 mol / L sodium hydroxide solution. The solution is stirred at a speed of 800 rpm at 40°C until complete dissolution. A pre-dissolution solution is obtained. The concentration of poly-glyoxime in the pre-dissolution solution is 0.1 g / mL. ​​S2. Co-solvent blending: after the pre-dissolution of the pre-solution is reduced to room temperature, a co-solvent is added to dissolve completely, to obtain a pre-solution, wherein the amount of the co-solvent added is 0.4 g / mL, and the co-solvent is 0.2 g / mL urea + 0.2 g / mL formamide; S3. Solution pH regulation: the pH regulator is added to the pre-solution in multiple times and mixed uniformly, the pH regulator is added to the pre-solution in multiple times and mixed uniformly, the pH of the pre-solution is adjusted to about 7, to obtain a poly-amino-oxime neutral solution, wherein the pH regulator is a 1 mol / L hydrochloric acid solution, and the single addition amount is 0.25 mL.

[0061] The poly-amino-oxime powder of Example 4 is the same as that of Example 1.

[0062] Figure 5 The dissolution state diagram of the poly-amino-oxime in the poly-amino-oxime neutral solution can be seen from the figure, when the co-solvent is 0.2 g / mL urea + 0.2 g / mL formamide, the polymer solution can maintain a clear and transparent state, and no obvious polymer precipitation occurs.

[0063] Example 5 A kind of base-sensitive nanomaterial doped hydrogel material, the preparation method is as follows: The poly-amino-oxime neutral solution prepared according to Example 4 is scaled up to 50 mL, stirred at 800 rpm for 2 h, then 50 mg of base-sensitive COF nanomaterial is added to the solution, and stirred at 800 rpm for 4 h, then 3 g of acrylamide, 250 mg of N,N'-methylene bisacrylamide, and 25 mg of azobisdimethylaminoformamide hydrochloride are added to the solution, stirred for 30 min, and then polymerized under ultraviolet light for 10 min to obtain a hydrogel material as shown in FIG. 6. Figure 6 At the same time Figure 7 As can be seen from FIG. 6, the gel has a perfect macroscopic morphology and a complete microstructure.

[0064] Comparative Example 1 A preparation method of a poly-amino-oxime solution, comprising the following steps: S1. Dissolution of poly-amino-oxime: 0.1 g of poly-amino-oxime powder is dissolved in 1 mL of 0.12 mol / L sodium hydroxide solution, stirred at 30°C and 600 rpm until completely dissolved, to obtain a poly-amino-oxime solution, and the concentration of poly-amino-oxime in the poly-amino-oxime solution is 0.1 g / mL; S2. Solution pH regulation: 3 mol / L hydrochloric acid solution is added in multiple times (single addition amount is 0.25 mL), and the pH of the pre-dissolved pre-solution is adjusted to about 7, as shown in FIG. 7. Figure 8 As shown in FIG. 7, the poly-amino-oxime precipitates rapidly from the solution, and cannot be further processed.

[0065] The polyamidoxime powder of Comparative Example 1 is the same as that of Example 1.

[0066] Comparative Example 2 A method for preparing a polyamidoxime solution includes the following steps: S1. Pre-dissolution of polyamidoxime: 0.1 g of polyamidoxime powder is dissolved in 1 mL of 0.12 mol / L sodium hydroxide solution, and stirred at 600 rpm and 30°C until completely dissolved to obtain a pre-dissolved solution, and the concentration of polyamidoxime in the pre-dissolved solution is 0.1 g / mL; S2. Blend of cosolvent: after the pre-dissolved solution is cooled to room temperature, a cosolvent is added to obtain a solution, wherein the cosolvent is urea, and the addition amount is 0.6 g / mL, and the viscosity of the solution is too large, and there is obvious precipitation; S3. pH adjustment of the solution: the pH adjuster is added to the solution in multiple times and mixed uniformly to adjust the pH of the solution to about 7 to obtain a neutral polyamidoxime solution, wherein the pH adjuster is 3 mol / L hydrochloric acid solution, and the single addition amount is 0.25 mL.

[0067] The polyamidoxime powder of Comparative Example 1 is the same as that of Example 1.

[0068] The neutral polyamidoxime solution has obvious polymer precipitation, and a clear polyamidoxime solution cannot be obtained.

[0069] Comparative Example 3 A method for preparing a polyamidoxime solution includes the following steps: S1. Pre-dissolution of polyamidoxime: 0.1 g of polyamidoxime powder is dissolved in 1 mL of 0.12 mol / L sodium hydroxide solution, and stirred at 600 rpm and 30°C until completely dissolved to obtain a pre-dissolved solution, and the concentration of polyamidoxime in the pre-dissolved solution is 0.1 g / mL; S2. Blend of cosolvent: after the pre-dissolved solution is cooled to room temperature, a cosolvent is added to obtain a solution, wherein the cosolvent is urea, and the addition amount is 0.6 g / mL, and the viscosity of the solution is too large, and there is obvious precipitation; S3. pH adjustment of the solution: the pH adjuster is added to the solution in multiple times and mixed uniformly to adjust the pH of the solution to about 7 to obtain a neutral polyamidoxime solution, wherein the pH adjuster is 3 mol / L hydrochloric acid solution, and the single addition amount is 0.25 mL.

[0070] The polyamidoxime powder of Comparative Example 1 is the same as that of Example 1.

[0071] The acid concentration in the polyamidoxime solution is too high to cause polymer agglomeration and precipitation, and a clear polyamidoxime solution cannot be obtained.

[0072] Comparative Example 4 A preparation of a double network hydrogel material under alkaline conditions, comprising the following steps: Dissolve 0.1 g of poly-amidoxime powder in 0.12 mol / L sodium hydroxide solution, the amount of sodium hydroxide solution is 1 mL, stir at 30°C and 600 rpm until completely dissolved, to obtain a poly-amidoxime solution, the concentration of poly-amidoxime in the solution is 0.1 g / mL; Add 120 mg of acrylamide, 10 mg of N,N'-methylene bisacrylamide, and 1 mg of azobisdimethylaminoform hydrochloride to the above poly-amidoxime solution, stir for 30 min, then initiate polymerization under ultraviolet light for 10 min.

[0073] The results are shown in the following table: Figure 9 Due to the rapid quenching of free radicals by OH - under alkaline conditions, the monomer polymerization rate is limited, and the overall solution viscosity is high, making it difficult to form a gel.

[0074] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a neutral solution of polyamidoximes, characterized in that: The steps include: S1. Predissolving polyamidooxime: The polyamidooxime is placed in an alkaline aqueous solution and completely dissolved to obtain a predissolved pre-solution, wherein the concentration of the base in the alkaline aqueous solution is 0.1 to 0.15 mol / L, and the concentration of the predissolved pre-solution polyamidooxime is 0.05 to 0.2 g / mL; S2 cosolvent blending: the cosolvent is added to the pre-dissolved pre-solution and dissolved completely to obtain a pre-solution, wherein the cosolvent is formamide, urea, guanidine hydrochloride, one or more, added in an amount of 0.05 ~ 0.5g / mL; S3. Solution pH control: adding a pH adjusting agent to the pre-solution and mixing uniformly until the pH value of the pre-solution is neutral to obtain a neutral solution of polyamidooxime, wherein the pH adjusting agent is an acidic aqueous solution with a concentration of 1 to 5 mol / L.

2. The method for preparing a neutral solution of polyamidoximes according to claim 1, wherein The pH adjuster in S3 is added in multiple times, and the single addition amount of the pH adjuster is 0.25~0.5mL / mL pre-solution.

3. The method for preparing a neutral solution of polyamidoximes according to claim 1, wherein The dissolution temperature in S1 is 30℃~45℃.

4. The method for preparing a neutral solution of polyamidoximes according to claim 1, wherein The cosolvent described in S2 is urea.

5. The method for preparing a neutral solution of polyamidoximes according to claim 4, wherein: The amount of the cosolvent added in S2 is 0.3-0.4 g / mL.

6. The method for preparing a neutral solution of polyamidoximes according to claim 2, wherein: The pH regulator in S3 is hydrochloric acid solution with a concentration of 1~3 mol / L, and the single addition amount is 0.25 mL / mL pre-solution.

7. A neutral polyamidooxime solution prepared by the method for preparing a neutral polyamidooxime solution according to any one of claims 1 to 6.

8. Use of the neutral solution of polyamidooxime according to claim 7 in the preparation of polyamidooxime materials.

9. The application according to claim 8, characterized in that: The preparation process of the polyamidooxime material includes any one of mixing, film forming, injection molding, printing, electrospinning, compounding and cross-linking.

10. A polyamidoxime material, characterized in that: The polyamidooxime material is prepared in a reaction system comprising the polyamidooxime neutral solution according to claim 7.

Images