Manganese dioxide heterojunction and preparation method and application thereof

Abstract

The application discloses a manganese dioxide heterostructure and a preparation method and application thereof, and the preparation method is as follows: potassium permanganate solution and manganese sulfate solution are respectively heated and dissolved, reaction is carried out by using a micro-channel reaction device, and through accurate regulation and control of the concentration, temperature and flow rate of the solution, a delta-manganese dioxide / alpha-manganese dioxide heterostructure or an alpha-manganese dioxide / gamma-manganese dioxide heterostructure is prepared, a potential scheme for continuous and controllable synthesis of the manganese dioxide heterostructure is provided, and the heterostructure can be applied to vulcanization of polysulfide sealant and can effectively improve the vulcanization efficiency of the polysulfide sealant.

Description

Technical Field

[0001] This invention relates to the field of polysulfide sealants, specifically to a manganese dioxide homogeneous structure, its preparation method, and its application. Background Technology

[0002] Polysulfide sealants possess excellent resistance to oil, low temperatures, various media, UV radiation, and aging. Furthermore, they exhibit superior adhesion and deformation resistance to materials such as steel, concrete, and glass. Therefore, polysulfide sealants are widely used for sealing and waterproofing aircraft cabins, passenger cabins, automobiles, subways, and fuel tanks. As a sealing material with a long history of application, it continues to play an irreplaceable role today. The matrix material of polysulfide sealants, liquid polysulfide rubber, consists of intertwined linear molecules. During application, a vulcanizing agent is used to crosslink these linear liquid polysulfide rubber molecules into a three-dimensional network structure, thereby achieving excellent sealing performance.

[0003] Manganese dioxide is abundant, inexpensive, and environmentally friendly, and possesses excellent vulcanization properties, making it widely used as a vulcanizing agent in polysulfide sealants. Simultaneously, manganese dioxide is also an environmentally friendly semiconductor material. When manganese dioxide is irradiated with light of energy greater than or equal to its band gap, some electrons in the valence band are excited and transition to the conduction band, generating photogenerated electrons and holes in the conduction and valence bands, respectively. These photogenerated electrons and holes can migrate to the surface of manganese dioxide, forming free radical groups with oxidation / reduction capabilities. These free radicals further attack the thiol groups in the polysulfide sealant, thereby achieving cross-linking.

[0004] Chinese patent document 201510897566.3 discloses a room-temperature vulcanizing two-component polysulfide sealant, its preparation and application method, which consists of two components, A and B, with a weight ratio of 8:1 to 10:1. Component A contains polysulfide rubber, coupling agent, low-density filler, lamellar filler, reinforcing agent and tackifier; component B contains manganese dioxide, plasticizer, accelerator and vulcanization retarder; it can maintain a density below 1.30 g / cm³. 3 Based on this, the mechanical properties, aging resistance and heat resistance of the sealant are improved; however, its vulcanization efficiency is relatively low.

[0005] To enhance the photocatalytic performance of semiconductors, the construction of semiconductor composite structures is commonly employed to broaden the semiconductor's photoresponse range and promote the separation and transfer of photogenerated carriers. Common semiconductor composite structures include heterojunctions and homojunctions. While heterojunctions possess excellent performance, their elemental complexity necessitates the separate synthesis of the two component materials before a second bonding reaction, making the process extremely time-consuming. In contrast, homojunctions have a relatively simple structure, requiring no introduction of a second component, and can achieve equally efficient separation of photogenerated carriers. Therefore, constructing manganese dioxide homojunctions can improve the efficiency of photo-assisted polysulfide sealing agent vulcanization. However, the controllable, continuous, and large-scale synthesis of manganese dioxide homojunctions remains a problem to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a manganese dioxide homojunction, its preparation method, and its application. By changing the temperature, concentration, and flow rate of the reactants, δ-manganese dioxide / α-manganese dioxide homojunction and α-manganese dioxide / γ-manganese dioxide homojunction can be rapidly, continuously, and stably produced, and can be applied to the vulcanizing agent of polysulfide sealants.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing a manganese dioxide homojunction includes the following steps: adding potassium permanganate solution and manganese sulfate solution to a microchannel reaction device, respectively, and obtaining δ-manganese dioxide / α-manganese dioxide homojunction or α-manganese dioxide / γ-manganese dioxide homojunction after the reaction;

[0009] The preparation conditions for the δ-manganese dioxide / α-manganese dioxide homojunction are as follows: the concentration ratio R of manganese sulfate solution to potassium permanganate solution in the microchannel reaction device is 0 < R ≤ 2, and the reaction temperature T is 0℃ ≤ T < 80℃.

[0010] The preparation conditions for α-manganese dioxide / γ-manganese dioxide homojunctions are as follows: the ratio R of the concentration of manganese sulfate solution to the concentration of potassium permanganate solution in the microchannel reaction device is in the range of 2 < R ≤ 6, and the reaction temperature T is in the range of 0℃ ≤ T < 100℃.

[0011] Preferably, the concentration C1 of the potassium permanganate solution is in the range of 0 mol / L < C1 ≤ 6 mol / L.

[0012] Preferably, the concentration C2 of the manganese sulfate solution is in the range of 0 mol / L < C2 ≤ 6 mol / L.

[0013] Preferably, the flow rate Q1 of potassium permanganate solution entering the microchannel reaction device is in the range of 0 mL / min < Q1 ≤ 300 mL / min.

[0014] Preferably, the flow rate Q2 of the manganese sulfate solution entering the microchannel reaction device is in the range of 0 mL / min < Q2 ≤ 300 mL / min.

[0015] Preferably, the microchannel reaction device includes a raw material tank 1, a raw material tank 2, a reaction pump 1, a reaction pump 2, and a reaction vessel. The bottom of both raw material tank 1 and raw material tank 2 is equipped with a heating device 1. The reaction pump 1 is connected to raw material tank 1 and the reaction vessel respectively through a heat-insulated pipe. The reaction pump 2 is connected to raw material tank 2 and the reaction vessel respectively through a heat-insulated pipe.

[0016] Preferably, a second heating device is provided at the bottom of the reaction vessel.

[0017] Preferably, the microchannel reaction device further includes a product tank, and the outlet of the reaction tank is connected to the product tank via a pipe.

[0018] The present invention also claims protection for a manganese dioxide homojunction prepared using the aforementioned preparation method.

[0019] The present invention also claims the use of the aforementioned manganese dioxide homogeneous structure in polysulfide sealants.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) This invention provides a method for preparing manganese dioxide homojunctions. The microchannel reaction device has the advantages of excellent temperature control, high mass transfer efficiency and precise reaction flow control, which greatly improves the mixing efficiency of potassium permanganate solution and manganese sulfate solution in the reaction process. At the same time, due to the good heat exchange capacity of the reaction device, the occurrence of side reactions can be greatly reduced, ensuring the yield and purity of the product.

[0022] 2) This invention uses a microchannel method to prepare manganese dioxide homojunctions. All raw materials have the same reaction time, and the concentrations and chemical reaction rates of raw materials and products are relatively stable, allowing for precise control of reaction parameters.

[0023] 3) This invention uses a microchannel method to prepare manganese dioxide homojunctions, which is suitable for the continuous production of large quantities of manganese dioxide homojunctions. While ensuring product quality, different types of manganese dioxide homojunctions can be stably and continuously produced by simply changing the reaction parameters, which greatly reduces the difficulty of synthesizing manganese dioxide homojunctions.

[0024] 4) The δ-manganese dioxide / α-manganese dioxide homojunction and α-manganese dioxide / γ-manganese dioxide homojunction prepared by this invention can synergistically achieve efficient separation of photogenerated carriers, improve the vulcanization efficiency of polysulfide sealant, and achieve rapid polysulfide sealing. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some schematic diagrams of certain embodiments of the present invention, and therefore should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the microchannel device in the embodiment;

[0027] Figure 2 The X-ray diffraction pattern of the δ-manganese dioxide / α-manganese dioxide homojunction prepared in Example 1;

[0028] Figure 3 This is a graph showing the hardness variation of the δ-manganese dioxide / α-manganese dioxide homojunction prepared in Example 1;

[0029] Figure 4 This is a graph showing the hardness variation of the δ-manganese dioxide / α-manganese dioxide homojunction prepared in Example 2;

[0030] Figure 5 The X-ray diffraction pattern of the α-manganese dioxide / γ-manganese dioxide homojunction prepared in Example 3;

[0031] Figure 6 This is a graph showing the hardness variation of the α-manganese dioxide / γ-manganese dioxide homojunction prepared in Example 3;

[0032] Figure 7 The graph shows the hardness variation of the α-manganese dioxide prepared in Comparative Example 1.

[0033] Figure 1 In the middle, 1. Raw material tank one; 2. Raw material tank two; 3. Reaction pump one; 4. Reaction pump two; 5. Insulated pipe; 6. Reaction tank; 7. Heating device one; 8. Heating device two; 9. Product tank. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] The terms "first," "second," etc., are used only for descriptive distinction and should not be interpreted as indicating or implying relative importance. Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be perfectly horizontal, but can be slightly tilted.

[0036] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0038] The present invention will be further described below through specific embodiments.

[0039] Example 1

[0040] A method for preparing a manganese dioxide homojunction includes the following steps:

[0041] A 1 mol / L potassium permanganate solution and a 1 mol / L manganese sulfate solution are added to raw material tank 1 and raw material tank 2, respectively. The potassium permanganate solution and manganese sulfate solution are heated to 75°C by heating device 7. Then, the potassium permanganate solution is fed into reaction tank 6 through reaction pump 3 at a flow rate of 50 mL / min via insulated pipe 5. At the same time, the manganese sulfate solution is fed into reaction tank 6 through reaction pump 4 at a flow rate of 50 mL / min via insulated pipe 5. The two solutions are controlled to enter reaction tank 6 at the same time to react. The reaction produces δ-manganese dioxide / α-manganese dioxide homojunctions, which are transported to product tank 9 by insulated pipe 5.

[0042] Example 2

[0043] A method for preparing a manganese dioxide homojunction includes the following steps:

[0044] A 1 mol / L potassium permanganate solution and a 1.5 mol / L manganese sulfate solution are added to raw material tank 1 and raw material tank 2, respectively. The potassium permanganate solution and manganese sulfate solution are heated to 65°C by heating device 7. Then, the potassium permanganate solution is fed into reaction tank 6 through reaction pump 3 at a flow rate of 65 mL / min via insulated pipe 5. At the same time, the manganese sulfate solution is fed into reaction tank 6 through reaction pump 4 at a flow rate of 65 mL / min via insulated pipe 5. The two solutions are controlled to enter reaction tank 6 at the same time to react. The reaction generates δ-manganese dioxide / α-manganese dioxide homojunctions, which are transported to product tank 9 through insulated pipe 5.

[0045] Example 3

[0046] A method for preparing a manganese dioxide homojunction includes the following steps:

[0047] A 1 mol / L potassium permanganate solution and a 3 mol / L manganese sulfate solution are added to raw material tank 1 and raw material tank 2, respectively. The potassium permanganate solution and the manganese sulfate solution are heated to 75°C by heating device 7. Then, the potassium permanganate solution is sent into reaction tank 6 through reaction pump 3 at a flow rate of 80 mL / min via insulated pipe 5. At the same time, the manganese sulfate solution is sent into reaction tank 6 through reaction pump 4 at a flow rate of 80 mL / min via insulated pipe 5. The two solutions are controlled to enter reaction tank 6 at the same time to react and generate α-manganese dioxide / γ-manganese dioxide homojunction, which is then transported to product tank 9 through insulated pipe 5.

[0048] Comparative Example 1

[0049] A method for preparing α-manganese dioxide includes the following steps:

[0050] A 0.5 mol / L potassium permanganate solution and a 1 mol / L manganese sulfate solution are added to raw material tank 1 and raw material tank 2, respectively. The potassium permanganate solution and manganese sulfate solution are heated to 90°C by heating device 7. Then, the potassium permanganate solution is fed into reaction tank 6 through reaction pump 3 at a flow rate of 60 mL / min via insulated pipe 5. At the same time, the manganese sulfate solution is fed into reaction tank 6 through reaction pump 4 at a flow rate of 60 mL / min via insulated pipe 5. The two solutions are controlled to enter reaction tank 6 at the same time to react and generate α-manganese dioxide, which is then transported to product tank 9 through insulated pipe 5.

[0051] X-ray diffraction analysis was performed on the manganese dioxide homojunctions prepared in Examples 1 and 3. Specific data can be found in [the table below]. Figure 2 , Figure 5 .

[0052] The vulcanizing effect of the products obtained in Examples 1-3 and Comparative Example 1 on polysulfide sealant was tested using the following method: 5g of manganese dioxide homojunction or α-manganese dioxide was added to a mortar, followed by 0.1g of tetramethylthiuram disulfide and 0.075g of stearic acid. The three substances were ground to ensure thorough mixing. After mixing, dibutyl phthalate was added dropwise while grinding to form a semi-dry paste, thus preparing the vulcanizing paste.

[0053] Weigh 30g of polysulfide sealant base paste, and add 3g of vulcanizing paste at a mass ratio of base paste to vulcanizing paste of 10:1. Mix thoroughly on a clean glass plate to obtain a light-assisted polysulfide sealant vulcanization sample. Place the sample into a specially made polytetrafluoroethylene mold with dimensions of 5cm × 5cm × 0.6cm to form it. Then, irradiate it with a xenon lamp for 30 minutes. Before irradiation, first adjust the distance between the xenon lamp and the polytetrafluoroethylene mold to 5cm, and then adjust the light power density of the xenon lamp at the mold to the required value (1140mW / cm²). 2 Preheat for 30 minutes, then observe the vulcanization process using a Shore hardness tester until the hardness reaches 50 HA. See [link to hardness change chart] for details. Figure 3 , Figure 4 , Figure 6 , Figure 7 .

[0054] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a manganese dioxide homojunction, characterized in that, The process includes the following steps: adding potassium permanganate solution and manganese sulfate solution to a microchannel reaction device, respectively, and obtaining δ-manganese dioxide / α-manganese dioxide homojunctions after the reaction; The microchannel reaction device includes a raw material tank 1, a raw material tank 2, a reaction pump 1, a reaction pump 2, and a reaction tank. Both raw material tank 1 and raw material tank 2 are equipped with a heating device 1 at their bottoms. The reaction pump 1 is connected to the raw material tank 1 and the reaction tank respectively through a heat-insulated pipe. The reaction pump 2 is connected to the raw material tank 2 and the reaction tank respectively through a heat-insulated pipe. The bottom of the reaction vessel is equipped with a second heating device; The microchannel reaction device also includes a product tank, and the outlet of the reaction tank is connected to the product tank through an insulated pipe; A 1 mol / L potassium permanganate solution and a 1 mol / L manganese sulfate solution were added to raw material tank one and raw material tank two, respectively. The potassium permanganate solution and manganese sulfate solution were heated to 75°C using heating device one. Then, the potassium permanganate solution was fed into the reaction tank through a heat-insulated pipe at a flow rate of 50 mL / min using reaction pump one, and the manganese sulfate solution was fed into the reaction tank through a heat-insulated pipe at a flow rate of 50 mL / min using reaction pump two. The two solutions were controlled to enter the reaction tank at the same time to react and generate δ-manganese dioxide / α-manganese dioxide homojunctions, which were then transported to the product tank through the heat-insulated pipe.

2. A method for preparing a manganese dioxide homojunction, characterized in that, The process includes the following steps: adding potassium permanganate solution and manganese sulfate solution to a microchannel reaction device, respectively, and obtaining δ-manganese dioxide / α-manganese dioxide homojunctions after the reaction; The microchannel reaction device includes a raw material tank 1, a raw material tank 2, a reaction pump 1, a reaction pump 2, and a reaction tank. Both raw material tank 1 and raw material tank 2 are equipped with a heating device 1 at their bottoms. The reaction pump 1 is connected to the raw material tank 1 and the reaction tank respectively through a heat-insulated pipe. The reaction pump 2 is connected to the raw material tank 2 and the reaction tank respectively through a heat-insulated pipe. The bottom of the reaction vessel is equipped with a second heating device; The microchannel reaction device also includes a product tank, and the outlet of the reaction tank is connected to the product tank through an insulated pipe. A 1 mol / L potassium permanganate solution and a 1.5 mol / L manganese sulfate solution were added to raw material tank one and raw material tank two, respectively. The potassium permanganate solution and manganese sulfate solution were heated to 65°C using heating device one. Then, the potassium permanganate solution was fed into the reaction tank through a heat-insulated pipe at a flow rate of 65 mL / min using reaction pump one, and the manganese sulfate solution was fed into the reaction tank through a heat-insulated pipe at a flow rate of 65 mL / min using reaction pump two. The two solutions were controlled to enter the reaction tank at the same time to react and generate δ-manganese dioxide / α-manganese dioxide homojunctions, which were then transported to the product tank through the heat-insulated pipe.

3. A method for preparing a manganese dioxide homojunction, characterized in that, The process includes the following steps: adding potassium permanganate solution and manganese sulfate solution to a microchannel reaction device, respectively, and obtaining α-manganese dioxide / γ-manganese dioxide homojunctions after the reaction; The microchannel reaction device includes a raw material tank 1, a raw material tank 2, a reaction pump 1, a reaction pump 2, and a reaction tank. Both raw material tank 1 and raw material tank 2 are equipped with a heating device 1 at their bottoms. The reaction pump 1 is connected to the raw material tank 1 and the reaction tank respectively through a heat-insulated pipe. The reaction pump 2 is connected to the raw material tank 2 and the reaction tank respectively through a heat-insulated pipe. The bottom of the reaction vessel is equipped with a second heating device; The microchannel reaction device also includes a product tank, and the outlet of the reaction tank is connected to the product tank through an insulated pipe. A 1 mol / L potassium permanganate solution and a 3 mol / L manganese sulfate solution were added to raw material tank one and raw material tank two, respectively. The potassium permanganate solution and manganese sulfate solution were heated to 75°C using heating device one. Then, the potassium permanganate solution was fed into the reaction tank through a heat-insulated pipe at a flow rate of 80 mL / min using reaction pump one, and the manganese sulfate solution was fed into the reaction tank through a heat-insulated pipe at a flow rate of 80 mL / min using reaction pump two. The two solutions were controlled to enter the reaction tank at the same time to react and generate α-manganese dioxide / γ-manganese dioxide homojunctions, which were then transported to the product tank through the heat-insulated pipe.

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