A kind of multi-element molten salt and the method for synthesizing polymer with molten salt as catalyst

Abstract

The application provides a kind of multi-element molten salt and the method for synthesizing polymer with molten salt as catalyst, and relates to the field of organic material synthesis.The application provides a kind of multi-element molten salt, and the main components include aluminum chloride, low melting point inorganic salt mixture;The low melting point inorganic salt mixture is selected from sodium chloride and / or potassium chloride;On the other hand, a kind of method for synthesizing polymer is provided, with organic monomer as precursor, and the above-mentioned multi-element molten salt is creatively used as catalyst, which effectively reduces the temperature of polymerization reaction, avoids the carbonization problem of polymer caused by high temperature, and reduces the risk of serious pollution to the environment caused by using strong acid and strong base as catalyst.Therefore, the polymer synthesis method provided by the application has the advantages of low cost, simple process, environmental friendliness and the like, and is a kind of polymer synthesis method with universality and very high popularization value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic material synthesis, and in particular to a multi-component molten salt and a polymer synthesis method using molten salt as a catalyst. BACKGROUND

[0002] At present, organic conjugated aromatic polymer materials have been widely used in many engineering fields due to their controllable molecular structure, good physical / chemical stability, large specific surface area and controllable porous structure, and have important development potential and research value in various electrochemical energy storage and conversion devices and gas separation fields. However, in the synthesis of most organic conjugated aromatic polymers, a large amount of organic reagents are used as solvents, and strong acids and strong bases are used as catalysts. The large amount of organic reagents not only is harmful to health, but also causes serious environmental pollution.

[0003] Molten salt is a molten liquid state of salt, and most of its solid state is ionic crystal. After melting at high temperature, it forms an ionic melt, which is a molten salt system with unique properties. Inorganic molten salt is mainly composed of alkali metals or alkaline earth metals and halides, silicates, carbonates, nitrates and phosphates. Generally, molten salt has good electrical conductivity, low vapor pressure and high solubility, and can dissolve a variety of materials. The molten salt synthesis method is a relatively safe and environmentally friendly synthesis method. However, most molten salt reaction systems require high reaction temperature to reach the melting point of the salt, which promotes the reaction to proceed, which inevitably causes carbonization of the polymer during the reaction process, and greatly limits the types of reactive monomers suitable for the molten salt system and the synthesis efficiency of the polymer.

[0004] In summary, it is of great significance to develop a molten salt system that can realize low-temperature polymerization and is suitable for a variety of organic monomers. SUMMARY

[0005] The present application aims to provide a multi-component molten salt and a polymer synthesis method using molten salt as a catalyst, to solve the technical problem of high polymerization reaction temperature in the prior art.

[0006] To solve the above technical problems, the present application provides a multi-component molten salt, which comprises aluminum chloride and a low-melting-point inorganic salt mixture in its composition.

[0007] The low-melting-point inorganic salt mixture is selected from sodium chloride and / or potassium chloride.

[0008] The aluminum chloride is the main effective component for catalyzing the polymerization reaction, but the pure aluminum chloride cannot reach the molten state at low temperature, so the ring tri-molecular reaction cannot be induced. Therefore, the sodium chloride and potassium chloride are introduced into the reaction to form a multi-component molten salt system through a large number of experimental verifications, and the temperature of the aluminum chloride entering the molten state is effectively reduced.

[0009] Further, the mole percentage of the aluminum chloride in the molten salt should be 50% or more.

[0010] On the other hand, the application also provides a polymer synthesis method using the multi-component molten salt as a catalyst, which at least includes the following steps:

[0011] Step 1, the organic monomer, the multi-component molten salt and the like are weighed according to the mole ratio of 1:(0.1-10) and uniformly mixed to obtain a first mixture;

[0012] Step 2, the first mixture is placed at 150-300 DEG C for reaction to obtain a second mixture;

[0013] Step 3, the second mixture is crushed and ground, and then subjected to acid washing, filtration, water washing, purification and drying at 80-100 DEG C to obtain the target organic polymer.

[0014] Further, the preparation method of the multi-component molten salt in step 1 is as follows:

[0015] Step S1, the aluminum chloride and the low-melting-point inorganic salt mixture are weighed in sequence;

[0016] The mole percentage of the aluminum chloride in the molten salt is 50% or more;

[0017] The low-melting-point inorganic salt mixture is selected from sodium chloride and / or potassium chloride;

[0018] Step S2, the aluminum chloride and the low-melting-point inorganic salt mixture are fully mixed and uniformly ground to obtain the multi-component molten salt.

[0019] Preferably, in step S1, the mole percentage of the aluminum chloride in the molten salt is 60-66%.

[0020] Preferably, the multi-component molten salt includes aluminum chloride, sodium chloride and potassium chloride, and the mole ratio is 61:26:13.

[0021] The binary molten salt and the ternary molten salt can both be used as the Lewis acid catalyst to participate in the polymerization reaction to obtain the target organic polymer; preferably, the ternary molten salt, i.e. AlCl3-NaCl-KCl, and the obtained organic polymer has better crystallinity.

[0022] Further, the organic monomer in step 2 is selected from terephthalonitrile, phenoxazine, phenoxazine, hexaazatriphenylene (3Q) small molecules.

[0023] Further, the reaction time in step 2 is 2-48 hours.

[0024] Further, in step 3, the acid washing is to put the second mixture into an excess of 1 mol / L hydrochloric acid solution, and stir for 20-24 hours.

[0025] The present application adopts an excess of dilute hydrochloric acid solution to wash the reaction product, mainly to completely clean the multi-component molten salt as a catalyst.

[0026] Further, in step 3, the purification method is selected from organic reagent washing or Soxhlet extraction.

[0027] By different purification methods, the oligomers and impurities are dissolved or washed away, and the target organic polymer can be obtained.

[0028] Preferably, in the purification method in step 3, the organic reagent is selected from one or more of a mixture of ethanol, chloroform, tetrahydrofuran, toluene.

[0029] By using the above technical solution, the present application has the following beneficial effects:

[0030] The present application provides a multi-component molten salt and a polymer synthesis method using molten salt as a catalyst, using organic monomers as precursors, and creatively adding a multi-component molten salt with aluminum chloride as the main effective component in the self-polymerization reaction as a catalyst for the reaction, which can effectively reduce the temperature of the polymerization reaction, avoid the carbonization problem of the polymer caused by high temperature, and reduce the risk of serious environmental pollution caused by using strong acid and strong base as a catalyst. Therefore, the polymer synthesis method provided by the present application has the characteristics of low cost, simple process, and friendly environment, and is a polymer synthesis method with universality and high popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0032] Figure 1 The flow chart of the preparation method of the polymer material provided by the present application;

[0033] Figure 2Structure diagram of CTF-1 polymer material in the present application;

[0034] Figure 3 XRD pattern of CTF-1 polymer material in the present application.

[0035] Figure 4 Structure diagram of polyphenazine polymer material in the present application;

[0036] Figure 5 Mass spectrum pattern of polyphenazine polymer material in the present application;

[0037] Figure 6 Structure diagram of polyphenoxazine polymer material in the present application;

[0038] Figure 7 Mass spectrum pattern of polyphenoxazine polymer material in the present application;

[0039] Figure 8 Structure diagram of polyhexaazatriphenylene polymer material in the present application;

[0040] Figure 9 Mass spectrum pattern of polyhexaazatriphenylene polymer material in the present application.

[0041] Figure 10 XRD comparison diagram of organic monomer terephthalonitrile before and after heat treatment in Comparative Example 1;

[0042] Figure 11 XRD diagram of product after heat treatment of organic monomer terephthalonitrile and aluminum chloride in Comparative Example 2;

[0043] Figure 12 XRD comparison diagram of products obtained by self-polymerization of organic monomers respectively with binary and ternary molten salts in Example 5;

[0044] Figure 13 Comparison diagram of product obtained by self-polymerization of organic monomers with ternary molten salt in Example 5 and AB type stacking structure model;

[0045] Figure 14 Verification of the influence of different addition ratios of multi-component molten salt on the crystallinity of polymerization products by taking the preparation of CTF material as an example. DETAILED DESCRIPTION

[0046] The technical solutions of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0047] The application will be further explained in connection with specific embodiments.

[0048] As shown in the method for preparing CTF polymer material by using the multi-component molten salt as catalyst, the method generally comprises the following steps: Figure 1

[0049] Step 1: aluminum chloride, low-melting-point inorganic salt mixture are weighed in sequence, wherein the molar percentage of aluminum chloride should be 61-66%; after being mixed thoroughly, they are ground uniformly to obtain a multi-component molten salt;

[0050] Step 2: the organic monomer and the multi-component molten salt obtained in step 1 are mixed thoroughly according to a molar ratio of 1:(0.1-10) to obtain a first mixture;

[0051] Step 3: the first mixture is placed at 150-300℃ to perform self-polymerization reaction, and a second mixture is obtained;

[0052] Step 4: the second mixture is broken and ground, and is sequentially subjected to acid washing, filtration, water washing, purification, and drying at 80-100℃ to obtain a target organic polymer.

[0053] Example 1

[0054] As shown in the method for preparing CTF polymer material by using the multi-component molten salt as catalyst, the method generally comprises the following steps: Figures 2-3 Step T1: aluminum chloride, sodium chloride and potassium chloride are weighed in sequence according to a molar ratio of 61:26:13, and are mixed thoroughly and ground uniformly to obtain a ternary molten salt;

[0055] Step T2: the organic monomer terephthalonitrile and the ternary molten salt obtained in step 1 are mixed thoroughly according to a molar ratio of 1:0.5, and are ground uniformly to obtain a first mixture;

[0056] Step T3: the first mixture is transferred into a quartz tube, the quartz tube is vacuumized and sealed, the sealed quartz tube is placed in an oven to react at 180℃ for 24h, and is taken out after being cooled naturally to obtain a white product;

[0057] Step T4: the white product is broken and ground, and is transferred into a beaker containing excess 1 mol / L dilute hydrochloric acid to perform acid washing, and is stirred for 24h to remove the molten salt, and is filtered, and is washed with deionized water until neutral. Then, the filtered material is washed and filtered with ethanol, chloroform and tetrahydrofuran respectively to remove terephthalonitrile and oligomers and other impurities, and is placed in an oven at 80℃ to dry to obtain a polymer material CTF-1.

[0058]

[0059] ​​The CTF-1 obtained in Example 1 was subjected to organic element analysis by using element analysis method, and the results are shown in Table 1.

[0060] Table 1 Organic element analysis of CTF-1:

[0061]

[0062] As can be seen from Table 1, the carbon-nitrogen ratio of the organic polymer material prepared according to the method provided in the present application is basically consistent with the theoretical value, proving that the CTF polymer material is successfully synthesized.

[0063] As shown in Figures 2-3 , the XRD spectrum of the polymer material CTF-1 obtained according to the polymerization method provided in the present application is basically consistent with the theoretical XRD spectrum, the structure is basically the same, and the crystallization state is good.

[0064] Example 2

[0065] As shown in Figures 4-5 , the present embodiment provides a method for preparing a polyphenazine polymer material using a multi-element molten salt as a catalyst.

[0066] Step T1: aluminum chloride, sodium chloride and potassium chloride were weighed according to a molar ratio of 63:24:13, mixed thoroughly and ground uniformly to obtain a ternary molten salt;

[0067] Step T2: the organic monomer phenazine and the ternary molten salt obtained in step 1 were mixed according to a molar ratio of 1:5, ground uniformly to obtain a first mixture;

[0068] Step T3: the first mixture was transferred into a quartz tube, the quartz tube was vacuumized and sealed. The sealed quartz tube was placed in an oven and reacted at 250℃ for 24h, and then taken out after natural cooling to obtain a black product;

[0069] Step T4: the black product was crushed and ground, then transferred into a beaker containing excess 1mol / L dilute hydrochloric acid for acid washing, stirred for 24h to remove the molten salt, filtered, and then Soxhlet extracted with deionized water, ethanol and toluene for 24h respectively to remove impurities such as phenazine and oligomers. After that, the product was placed in an oven at 80℃ for drying to obtain a black product, i.e. a polyphenazine polymer material.

[0070] As shown in Figures 4-5 , the mass spectrum of the black product prepared in the present embodiment is basically consistent with the theoretical mass spectrum of 3, 4, 5 and 6 phenazine polymers, thereby proving that the self-polymerization reaction of phenazine is successfully completed under the catalysis of the ternary molten salt provided in the present application, and the black product, i.e. the polyphenazine polymer material, is generated.

[0071] Example 3

[0072] As Figures 6-7 shown, the present embodiment provides a method for preparing polyphenoxazine polymer material using a multi-element molten salt as a catalyst.

[0073] Step T1: aluminum chloride, sodium chloride, potassium chloride were weighed according to the molar ratio of 65:21:14, mixed thoroughly and ground uniformly to obtain a ternary molten salt;

[0074] Step T2: the organic monomer phenoxazine and the ternary molten salt obtained in step 1 were mixed according to a molar ratio of 1:5, ground uniformly to obtain a first mixture;

[0075] Step T3: the first mixture was transferred to a quartz tube, the quartz tube was vacuumed and sealed. The sealed quartz tube was placed in an oven at 250°C for 24h, and then taken out after natural cooling to obtain a black product;

[0076] Step T4: the black product was crushed and ground, then transferred into a beaker containing excess 1mol / L dilute hydrochloric acid for acid washing, stirred for 24h to remove the molten salt, filtered, and then Soxhlet extracted with deionized water, ethanol and toluene for 24h respectively to remove impurities such as phenoxazine and oligomers. Finally, the product was dried in an oven at 80°C to obtain a black product, i.e. polyphenoxazine polymer material.

[0077] As Figure 7 shown, the mass spectrum of the black product prepared in the present embodiment is basically consistent with the theoretical mass spectrum of 20 phenoxazine polymers, which proves that the self-polymerization reaction of phenoxazine successfully occurs under the catalysis of the ternary molten salt provided by the present application, and polyphenoxazine polymer material is generated.

[0078] Example 4

[0079] As Figures 8-9 shown, the present embodiment provides a method for preparing hexaazatriphenylene polymer material using a multi-element molten salt as a catalyst.

[0080] Step T1: aluminum chloride, sodium chloride, potassium chloride were weighed according to the molar ratio of 66:20:14, mixed thoroughly and ground uniformly to obtain a ternary molten salt;

[0081] Step T2: the organic monomer hexaazatriphenylene and the ternary molten salt obtained in step 1 were mixed according to a molar ratio of 1:5, ground uniformly to obtain a first mixture;

[0082] Step T3: the first mixture was transferred to a quartz tube, the quartz tube was vacuumed and sealed. The sealed quartz tube was placed in an oven at 250°C for 24h, and then taken out after natural cooling to obtain a black product;

[0083] In step T4, the black product is crushed and ground, then transferred to a beaker containing excess 1 mol / L dilute hydrochloric acid for acid washing. The mixture is stirred for 24 hours to remove molten salt. After filtration, it is extracted with deionized water, ethanol, and toluene for 24 hours each to remove impurities such as hexaazatrinaphthalene and oligomers. The product is then dried in an oven at 100°C to obtain the black product, which is the polyhexaazatrinaphthalene polymer material.

[0084] like Figure 9 As shown, the mass spectrum of the black product prepared in this embodiment is basically consistent with the theoretical mass spectra of hexaazatrinaphthalene polymerization 2, 3, 4, 5, 6, and 7, proving that the self-polymerization reaction of hexaazatrinaphthalene monomer successfully occurred under the catalysis of the ternary molten salt provided by this invention, and generated polyhexaazatrinaphthalene polymer material.

[0085] Comparative Example 1

[0086] Step D1: Place the pure organic monomer terephthalonitrile into a quartz tube, evacuate the quartz tube, and seal it. Place the sealed quartz tube in an oven and react at 200°C for 24 hours. After natural cooling, remove the tube to obtain the first white product.

[0087] In step D2, the first white product was crushed, ground, and washed with deionized water to remove impurities produced in the reaction. The product was then dried in an oven at 80°C to obtain the first comparative sample.

[0088] like Figure 10 As shown, analysis of the first comparative sample using X-ray diffraction patterns reveals that the XRD pattern of the product obtained after reacting the organic monomer terephthalonitrile at 200℃ for 24 hours is basically the same as that of the raw material before the reaction, proving that simple heat treatment cannot induce the organic monomer to undergo self-polymerization.

[0089] Comparative Example 2

[0090] Step D1: The pure organic monomer terephthalonitrile and aluminum chloride are placed in a quartz tube at a molar ratio of 1:0.5. The quartz tube is then evacuated and sealed. The sealed quartz tube is placed in an oven and reacted at 200°C for 24 hours. After natural cooling, it is removed to obtain the second white product.

[0091] In step D2, the second white product was crushed, ground, and washed with deionized water to remove impurities produced in the reaction. The product was then dried in an oven at 80°C to obtain the second control sample.

[0092] like Figure 11 As shown, since pure aluminum chloride cannot reach a molten state at 200℃ and therefore cannot induce cyclotrimerization, the mixture of organic monomers and pure aluminum chloride did not undergo self-polymerization at 200℃.Figure 11 It can also be seen from the XRD pattern of the second comparative example sample that no new crystalline peaks appear.

[0093] Example 5

[0094] As shown in Table 1, the present embodiment verifies the different beneficial effects of three kinds of multi-component molten salts participating in the self-polymerization reaction of the organic monomer. Figures 12-13

[0095] The experimental steps of the present embodiment are basically the same as those of Example 1, and the difference lies in that three kinds of multi-component molten salts with the molar ratio as shown in Table 2 are respectively prepared in step T1.

[0096] Table 2 Molar ratio of each component in three kinds of multi-component molten salts

[0097]

[0098] The self-polymerization reaction of the organic monomer terephthalonitrile with the three kinds of multi-component molten salts described in Table 2 is carried out, and three kinds of compounds are obtained accordingly. Figure 12 As can be seen from the comparison of the XRD patterns of the three kinds of CTF materials in Table 3, the XRD pattern of the compound obtained in the present embodiment is basically consistent with the AB-type stacking structure model, proving that the three kinds of compounds synthesized are CTF materials. Figure 13 As can be seen from the comparison of the XRD patterns of the three kinds of CTF materials in Table 3, the XRD pattern of the compound obtained in the present embodiment is basically consistent with the AB-type stacking structure model, proving that the three kinds of compounds synthesized are CTF materials.

[0099] Example 6

[0100] As shown in Table 4, the present embodiment verifies the influence of the addition ratio of different molten salts on the crystallinity of the reaction product. Figure 14

[0101] The steps of preparing the CTF material in the present embodiment are basically the same as those of Example 1, and the difference lies in that the molar ratio of the organic monomer terephthalonitrile to the ternary molten salt in step 2 is divided into five groups of 1:0.3, 1:0.5, 1:0.8, 1:1 and 1:2, and the self-polymerization reaction is carried out respectively to obtain five groups of CTF materials.

[0102] The five groups of CTF materials obtained in the present embodiment are analyzed by X-ray diffraction pattern, and as shown in Table 5, the CTF material obtained under the condition of the molar ratio of 1:0.5 has the best crystallinity. Figure 14 The molar ratio of the organic monomer to the multi-component molten salt provided by the present application is 1:(0.1-10), and the addition amount of the multi-component molten salt has a significant influence on the crystallinity of the reaction product, and the degree of influence on the crystallinity of the product slightly differs depending on the difference of the organic monomer. ​​

[0103] Table 3: Summary of experimental results of each example and comparative example In summary, as shown in Table 3, the multi-component molten salt provided by the present application can participate in the self-polymerization reaction of various organic monomers as a Lewis acid catalyst, avoiding the pollution of the environment by using traditional strong acid and strong base; the self-polymerization temperature can be controlled and the crystallinity of the polymerization product can be improved by adjusting the type of the added molten salt, and the crystallinity of the polymerization product obtained by the ternary molten salt is the best; the total amount of the ternary molten salt has a significant influence on the crystallinity of the polymerization product; on the other hand, the polymer synthesis method provided by the present application using the above multi-component molten salt as the catalyst is a polymer synthesis method with low cost, simple process, universality and high popularization value.

[0104] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but 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 or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for polymer synthesis with a polyatomic molten salt as a catalyst, characterized by, The method comprises the following steps: Step 1, according to the molar ratio of 1:(0.1-10), sequentially take the organic monomer, the multi-component molten salt, and uniformly mix to obtain a first mixture; The components of the molten salt include aluminum chloride and a low-melting-point inorganic salt mixture; The low-melting-point inorganic salt mixture includes sodium chloride and potassium chloride; The molar percentage of aluminum chloride in the molten salt should be 50% or more; The organic monomer is selected from p-phenylenedinitrile, phenoxazine, phenoxazine, and hexaazatriphenylene small molecules; Step 2, the first mixture is placed at 150-300℃ for reaction to obtain a second mixture; Step 3, the second mixture is crushed and ground, and sequentially subjected to acid washing, filtration, water washing, purification, and drying at 80-100℃ to obtain the target organic polymer.

2. The method of synthesis of claim 1, wherein, The preparation method of the multi-component molten salt in step 1 is as follows: Step S1, sequentially take aluminum chloride and a low-melting-point inorganic salt mixture; The molar percentage of aluminum chloride in the molten salt is 50% or more; The low-melting-point inorganic salt mixture includes sodium chloride and potassium chloride; Step S2, the aluminum chloride and the low-melting-point inorganic salt mixture are fully mixed and uniformly ground to obtain the multi-component molten salt.

3. The method of synthesis of claim 2, wherein, In step S1, the molar percentage of aluminum chloride in the molten salt is 60%-66%.

4. The method of synthesis of claim 1, wherein, The reaction time in step 2 is 2-48 hours.

5. The method of synthesis of claim 1, wherein, In step 3, the acid washing is placing the second mixture into an excess of a hydrochloric acid solution with a concentration of 1 mol / L and stirring for 20-24 hours.

6. The method of synthesis of claim 1, wherein, In step 3, the purification method is selected from organic reagent washing or Soxhlet extraction.

7. The method of synthesis of claim 6, wherein, In the purification method in step 3, the organic reagent is selected from a mixture of one or more of ethanol, chloroform, tetrahydrofuran, and toluene.

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