Preparation method of multi-block stereoregular polythioether

Abstract

The invention discloses a preparation method of multi-block stereoregular polythioether, and belongs to the technical field of polythioether synthesis. The method comprises the following steps: firstly, mixing butyl acrylate, a free radical initiator, a polythiocarbonate chain transfer agent, a first sulfur-containing monomer and N, N-dimethylacetamide, and carrying out free radical polymerization reaction in an inert atmosphere to form a first polymer block; and adding a second sulfur-containing monomer and a quaternary ammonium salt catalyst into the reaction system, and carrying out anionic ring-opening polymerization reaction to form a second polymer block, thereby obtaining the multi-block stereoregular polythioether. By means of the dynamic reversible chain transfer characteristic of thioester bonds, efficient connection of polymerization reactions of different mechanisms is achieved, the intermediate purification step is avoided, and the technological process is remarkably simplified. The obtained polymer has a clear block structure, high stereoregularity and controllable molecular weight, and is suitable for the fields of engineering plastics, special elastomers, functional coating materials and the like.

Description

Technical Field

[0001] This invention belongs to the field of polysulfide synthesis technology, and particularly relates to a method for preparing multi-block stereoregular polysulfides. Background Technology

[0002] Polysulfides are a class of polymeric materials whose main chain contains sulfide structural units. Due to the polarity, flexibility, and potential metal coordination ability of sulfur atoms in their chain segments, they show promising application prospects in fields such as specialty elastomers, damping materials, gas separation membranes, and adhesives. Therefore, developing synthetic methods that can precisely control the polymer sequence structure and stereoregularity is crucial for achieving precise regulation of the properties of polysulfide materials.

[0003] Currently, precise synthesis methods for polysulfides remain limited. Anionic ring-opening polymerization of cyclothiopropane monomers (such as 2-phenoxymethylcyclothiopropane, POMT) can achieve living controlled polymerization, which is one of the effective ways to achieve controlled synthesis of polysulfide structures. However, polysulfide materials obtained from a single cyclothiopropane monomer are liquid at room temperature and have poor mechanical properties. Furthermore, the living polymerization of multi-block polysulfides typically requires the sequential addition of different monomers under a single polymerization mechanism, and each polymerization step requires cumbersome purification steps to remove residual monomers, which is time-consuming.

[0004] Therefore, developing a polymerization method that can circumvent multi-step purification, achieve efficient connection of active centers with different mechanisms, and precisely combine flexible segments (such as polyacrylates) with stereoregular polysulfide hard segments is of great scientific significance and industrial application value for significantly improving synthesis efficiency and creating novel multi-block polysulfide materials with excellent mechanical properties and customizable functions. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing multi-block stereoregular polysulfides, solving the technical problems of "difficulty in directly and efficiently connecting different polymerization mechanisms and cumbersome multi-step synthesis process", thereby simplifying the process and obtaining high-performance stereoregular polysulfide materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a multi-block stereoregular polysulfide includes the following steps: (1) Butyl acrylate, free radical initiator, polythiocarbonate chain transfer agent, first sulfur-containing monomer and N,N-dimethylacetamide are mixed and subjected to free radical polymerization at 60~80℃ for 8~16h under an inert atmosphere to form the first polymer block; (2) Add the second sulfur-containing monomer and quaternary ammonium salt catalyst to the reaction system of step (1), and carry out anionic ring-opening polymerization reaction at 60~80℃ for 12h to form the second polymer block, thereby obtaining the multi-block stereoregular polysulfide; In step (2), the mass ratio of the second sulfur-containing monomer added to the first sulfur-containing monomer in step (1) is (10-30):1, and the mass ratio of the quaternary ammonium salt catalyst added to the first sulfur-containing monomer in step (1) is (1-2):1.

[0007] Furthermore, the first sulfur-containing monomer is dibenzo[c,e]oxazo-5(7H)-thione.

[0008] Furthermore, the second sulfur-containing monomer is at least one of 2-phenoxymethylcyclothiopropane and 2-butoxymethylcyclothiopropane.

[0009] Furthermore, the polythiocarbonate chain transfer agent is at least one of bis(methoxycarbonylmethyl)trithiocarbonate and 4-cyano-4-(((phenylethylthio)thiocarbonyl)thio)valerate.

[0010] Furthermore, the quaternary ammonium salt catalyst is tetrabutylammonium chloride.

[0011] Furthermore, the free radical initiator is azobisisobutyronitrile (AIBN).

[0012] Furthermore, the mass ratio of the first sulfur-containing monomer, butyl acrylate, free radical initiator, polythiocarbonate chain transfer agent, and N,N-dimethylacetamide is 1:(20-50):(0.01-0.05):(0.2-0.5):(100-500).

[0013] On the other hand, the present invention also provides a multi-block stereoregular polysulfide, obtained by the aforementioned method for preparing multi-block stereoregular polysulfide.

[0014] On the other hand, the aforementioned multi-block stereoregular polysulfides are used in the preparation of engineering plastics, special elastomers and functional coating materials.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: 1. This invention achieves simultaneous and precise control of sequence structure and stereoregularity, solving the technical problem of incompatibility between the two in traditional methods. Through a stepwise feeding strategy, the first polymer block is first precisely prepared by free radical polymerization; then, with the help of the specific design of the system, the second monomer is initiated in situ for stereoselective anionic ring-opening polymerization. This method can successfully prepare multi-block polysulfides with both clear microphase separation structure and high stereoregularity, laying the molecular foundation for its excellent comprehensive performance.

[0016] 2. This invention utilizes the synergistic effect of a carefully designed polythiocarbonate chain transfer agent, a first sulfur-containing monomer, and a quaternary ammonium salt catalyst. After the first step of the free radical polymerization reaction, the polymer chain end can be directly and efficiently converted in situ into an active center that can initiate the stereoselective anionic ring-opening polymerization of cyclothiopropane monomers under the action of the first sulfur-containing monomer. This conversion process is highly specific and compatible with other components in the system. Therefore, the entire multi-block polymerization process does not require any separation or purification of the intermediate polymer, achieving a seamless transition from free radical polymerization to ionic polymerization, fundamentally simplifying the process flow and improving synthesis efficiency and atom economy.

[0017] 3. The multi-block polysulfide material prepared by this invention exhibits balanced and adjustable mechanical and thermal properties. Due to the successful combination of rigid stereoregular polysulfide segments and flexible polyacrylate segments, the material simultaneously possesses high strength, high toughness, and good thermal stability. By adjusting the block ratio and monomer type, the material properties can be controlled over a wide range from soft elastomers to high-strength engineering plastics, meeting diverse application requirements. Attached Figure Description

[0018] Figure 1 This is a route diagram for the synthesis of multi-block stereoregular polysulfide in Example 1.

[0019] Figure 2 This is a route diagram for the synthesis of multi-block stereoregular polysulfides in Example 2.

[0020] Figure 3 This is a route diagram for the synthesis of multi-block stereoregular polysulfide in Example 3.

[0021] Figure 4 This is a route diagram for the synthesis of multi-block stereoregular polysulfide in Example 4. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0023] In this embodiment of the invention, a synergistic system of polythiocarbonate chain transfer agent, first sulfur-containing monomer, and tetrabutylammonium chloride catalyst was carefully designed to achieve efficient, in-situ conversion of active centers between different polymerization mechanisms. Specifically, under the action of a free radical initiator, dibenzo[c,e]oxazon-5(7H)-thion undergoes ring-opening self-polymerization, while butyl acrylate undergoes olefin free radical polymerization. Together, they form a polymer soft segment with specific thioester functional groups at the end and butyl acrylate structural units embedded in the chain, which is then ultimately embedded into the polythiocarbonate chain transfer agent. Subsequently, without further... Under any separation and purification conditions, the second sulfur-containing monomer undergoes ring-opening under the catalysis of tetrabutylammonium chloride. The catalyst activates the key sites of the thioester in the first-step polymer in situ, instantaneously generating sulfur anionic active centers, which in turn initiate the stereoselective anionic ring-opening polymerization of the second monomer, precisely constructing stereoregular polysulfide hard segments. This allows for the continuous and efficient, stereoregular polymerization of soft and hard segments without separating intermediate products. This method achieves in-situ switching from radical polymerization to anionic polymerization, significantly simplifying the process flow and improving synthesis efficiency and product performance while ensuring precise control of the block structure.

[0024] This invention provides a method for preparing multi-block stereoregular polysulfides, the core of which lies in a "one-pot, two-step, in-situ initiation" synthesis strategy. The preparation process of this method mainly includes the following steps: (1) Under nitrogen protection, azobisisobutyronitrile, dibenzo[c,e]oxazon-5(7H)-thione, butyl acrylate, polythiocarbonate chain transfer agent and N,N-dimethylacetamide are mixed evenly in a mass ratio of (0.01~0.05):(20~50):1:(0.2~0.5):(100~500) and reacted at 60~80℃ for 8~16h to form the first polymer block; (2) Add 10 to 30 times the mass of the second sulfur-containing monomer of dibenzo[c,e]oxazo-5(7H)-thionone and 1 to 2 times the mass of tetrabutylammonium chloride of dibenzo[c,e]oxazo-5(7H)-thionone to the above reaction system, continue the reaction for 12 h, pour the reaction solution into methanol, centrifuge to obtain the precipitate, and vacuum dry the precipitate to obtain multi-block stereoregular polysulfide.

[0025] The polythiocarbonate chain transfer agent is at least one of bis(methoxycarbonylmethyl)trithiocarbonate and 4-cyano-4-(((phenylethylthio)thiocarbonyl)thio)valerate.

[0026] The second sulfur-containing monomer is at least one of 2-phenoxymethylcyclothiopropane and 2-butoxymethylcyclothiopropane.

[0027] As a preferred embodiment of the present invention, the mass ratio of azobisisobutyronitrile, dibenzo[c,e]oxazon-5(7H)-thione, butyl acrylate, polythiocarbonate chain transfer agent and N,N-dimethylacetamide is 0.022:34:1:0.3:216.

[0028] As a preferred embodiment of the present invention, the mass ratio of the dibenzo[c,e]oxazo-5(7H)-thione to the second sulfur-containing monomer is 1:22.2.

[0029] As a preferred embodiment of the present invention, the mass ratio of dibenzo[c,e]oxazo-5(7H)-thione to tetrabutylammonium chloride is 1.25:1.

[0030] As a preferred embodiment of the present invention, the vacuum drying is performed at 80°C for 6 hours.

[0031] Example 1 This embodiment describes a multi-block stereoregular polysulfide; the specific synthesis process is detailed below. Figure 1 .

[0032] Raw material ratio: Azobisisobutyronitrile: 10.8mg, dibenzo[c,e]oxazo-5(7H)-thione: 500mg, butyl acrylate: 17g, 4-cyano-4-(((phenylethylthio)thiocarbonyl)thio)valeric acid: 148mg, 2-phenoxymethylcyclothiopropane: 11.1g, tetrabutylammonium chloride: 625mg.

[0033] Preparation process: (1) Under nitrogen protection, 10.8 mg of azobisisobutyronitrile, 500 mg of dibenzo[c,e]oxazon-5(7H)-thione, 17 g of butyl acrylate and 148 mg of 4-cyano-4-(((phenethylthio)thiocarbonyl)thio)valeric acid were added to 115 mL of N,N-dimethylacetamide and mixed evenly. The mixture was reacted at 70 °C for 12 h to form the first polymer block; (2) Add 11.1 g of 2-phenoxymethylcyclothiopropane and 625 mg of tetrabutylammonium chloride to the above reaction system, continue the reaction for 12 h, pour the reaction solution into methanol, centrifuge to obtain the precipitate, and vacuum dry the precipitate to obtain multi-block stereoregular polysulfide.

[0034] Example 2; This embodiment describes a multi-block stereoregular polysulfide; the specific synthesis process is detailed below. Figure 2 .

[0035] Raw material ratio: Azobisisobutyronitrile: 10.8mg, dibenzo[c,e]oxazon-5(7H)-thione: 500mg, butyl acrylate: 17g, bis(methoxycarbonylmethyl)trithiocarbonate: 148mg, 2-phenoxymethylcyclothiopropane: 11.1g, tetrabutylammonium chloride: 625mg.

[0036] Preparation process: (1) Under nitrogen protection, 10.8 mg of azobisisobutyronitrile, 500 mg of dibenzo[c,e]oxazon-5(7H)-thione, 17 g of butyl acrylate and 148 mg of bis(methoxycarbonylmethyl)trithiocarbonate were added to 115 mL of N,N-dimethylacetamide and mixed evenly. The mixture was reacted at 70 °C for 12 h to form the first polymer block; (2) Add 11.1 g of 2-phenoxymethylcyclothiopropane and 625 mg of tetrabutylammonium chloride to the above reaction system, continue the reaction for 12 h, pour the reaction solution into methanol, centrifuge to obtain the precipitate, and vacuum dry the precipitate to obtain multi-block stereoregular polysulfide.

[0037] Example 3; This embodiment describes a multi-block stereoregular polysulfide; the specific synthesis process is detailed below. Figure 3 .

[0038] Raw material ratio: Azobisisobutyronitrile: 10.8mg, dibenzo[c,e]oxazo-5(7H)-thione: 500mg, butyl acrylate: 17g, 4-cyano-4-(((phenylethylthio)thiocarbonyl)thio)valeric acid: 148mg, 2-butoxymethylcyclothiopropane: 11.1g, tetrabutylammonium chloride: 625mg.

[0039] Preparation process: (1) Under nitrogen protection, 10.8 mg of azobisisobutyronitrile, 500 mg of dibenzo[c,e]oxazon-5(7H)-thione, 17 g of butyl acrylate and 148 mg of 4-cyano-4-(((phenethylthio)thiocarbonyl)thio)valeric acid were added to 115 mL of N,N-dimethylacetamide and mixed evenly. The mixture was reacted at 70 °C for 12 h to form the first polymer block; (2) Add 11.1 g of 2-butoxymethylcyclothiopropane and 625 mg of tetrabutylammonium chloride to the above reaction system, continue the reaction for 12 h, pour the reaction solution into methanol, centrifuge to obtain the precipitate, and vacuum dry the precipitate to obtain multi-block stereoregular polysulfide.

[0040] Example 4; This embodiment describes a multi-block stereoregular polysulfide; the specific synthesis process is detailed below. Figure 4 .

[0041] Raw material ratio: Azobisisobutyronitrile: 10.8mg, dibenzo[c,e]oxazon-5(7H)-thione: 500mg, butyl acrylate: 17g, bis(methoxycarbonylmethyl)trithiocarbonate: 148mg, 2-butoxymethylcyclothiopropane: 11.1g, tetrabutylammonium chloride: 625mg.

[0042] Preparation process: (1) Under nitrogen protection, 10.8 mg of azobisisobutyronitrile, 500 mg of dibenzo[c,e]oxazon-5(7H)-thione, 17 g of butyl acrylate and 148 mg of bis(methoxycarbonylmethyl)trithiocarbonate were added to 115 mL of N,N-dimethylacetamide and mixed evenly. The mixture was reacted at 70 °C for 12 h to form the first polymer block; (2) Add 11.1 g of 2-butoxymethylcyclothiopropane and 625 mg of tetrabutylammonium chloride to the above reaction system, continue the reaction for 12 h, pour the reaction solution into methanol, centrifuge to obtain the precipitate, and vacuum dry the precipitate to obtain multi-block stereoregular polysulfide.

[0043] Example 5; Raw material ratio: Azobisisobutyronitrile: 5mg, dibenzo[c,e]oxazo-5(7H)-thione: 500mg, butyl acrylate: 10g, 4-cyano-4-(((phenylethylthio)thiocarbonyl)thio)valeric acid: 100mg, 2-phenoxymethylcyclothiopropane: 5g, tetrabutylammonium chloride: 500mg.

[0044] Preparation process: (1) Under nitrogen protection, 5 mg of azobisisobutyronitrile, 0.5 g of dibenzo[c,e]oxazon-5(7H)-thione, 10 g of butyl acrylate and 100 mg of 4-cyano-4-(((phenethylthio)thiocarbonyl)thio)valeric acid were added to 53 mL of N,N-dimethylacetamide and mixed evenly. The mixture was reacted at 60 °C for 8 h to form the first polymer block; (2) Add 5g of 2-phenoxymethylcyclothiopropane and 0.5g of tetrabutylammonium chloride to the above reaction system, continue the reaction for 12h, pour the reaction solution into methanol, centrifuge to obtain the precipitate, and vacuum dry the precipitate to obtain multi-block stereoregular polysulfide.

[0045] Example 6; Raw material ratio: Azobisisobutyronitrile: 25mg, dibenzo[c,e]oxazo-5(7H)-thione: 500mg, butyl acrylate: 25g, 4-cyano-4-(((phenylethylthio)thiocarbonyl)thio)valeric acid: 250mg, 2-phenoxymethylcyclothiopropane: 15g, tetrabutylammonium chloride: 1g.

[0046] Preparation process: (1) Under nitrogen protection, 25 mg of azobisisobutyronitrile, 500 mg of dibenzo[c,e]oxazon-5(7H)-thione, 25 g of butyl acrylate and 250 mg of 4-cyano-4-(((phenethylthio)thiocarbonyl)thio)valeric acid were added to 266 mL of N,N-dimethylacetamide and mixed evenly. The mixture was reacted at 80 °C for 16 h to form the first polymer block; (2) Add 15g of 2-phenoxymethylcyclothiopropane and 1g of tetrabutylammonium chloride to the above reaction system, continue the reaction for 12h, pour the reaction solution into methanol, centrifuge to obtain the precipitate, and vacuum dry the precipitate to obtain multi-block stereoregular polysulfide.

[0047] Comparative Example 1; The only difference between Comparative Example 1 and Example 1 is step (1). Step (1) is modified as follows: Under nitrogen protection, 0.19 mg of azobisisobutyronitrile, 300 mg of butyl acrylate and 2.6 mg of 4-cyano-4-(((phenylethylthio)thiocarbonyl)thio)valerate are added to 1.5 mL of N,N-dimethylacetamide and mixed evenly. The mixture is reacted at 70 °C for 12 h to form the first polymer block; the remaining steps are the same as in Example 1.

[0048] Comparative Example 2; The only difference between Comparative Example 2 and Example 1 is step (2). Step (2) is modified as follows: 195 mg of 2-phenoxymethylcyclothiopropane and 11 mg of sodium tetrafluoroborate are added to the above reaction system, the reaction is continued for 12 h, the reaction solution is poured into methanol, centrifuged to obtain precipitate, and the precipitate is vacuum dried to obtain multi-block stereoregular polysulfide; the remaining steps are the same as in Example 1.

[0049] Comparative Example 3: Under nitrogen protection, 0.19 mg of azobisisobutyronitrile, 8.8 mg of dibenzo[c,e]oxazo-5(7H)-thione, 300 mg of butyl acrylate, 2.6 mg of 4-cyano-4-(((phenylethylthio)thiocarbonyl)thio)valeric acid, 195 mg of 2-phenoxymethylcyclothiopropane, and 11 mg of tetrabutylammonium chloride were added to 1.5 mL of N,N-dimethylacetamide and mixed thoroughly. The mixture was reacted at 70 °C for 12 h. The reaction solution was poured into methanol, centrifuged to obtain a precipitate, and the precipitate was vacuum dried to obtain a multi-block stereoregular polysulfide.

[0050] Comparative Example 4; (1) Under nitrogen protection, 0.19 mg of azobisisobutyronitrile, 8.8 mg of dibenzo[c,e]oxazo-5(7H)-thione, 300 mg of butyl acrylate and 2.6 mg of 4-cyano-4-(((phenylethylthio)thiocarbonyl)thio)valeric acid were added to 1.5 mL of N,N-dimethylacetamide and mixed evenly. The mixture was reacted at 70 °C for 12 h. The reaction solution was poured into methanol and centrifuged to obtain a precipitate. The precipitate was then dried under vacuum to obtain the first polymer block. (2) Add 195 mg of 2-phenoxymethylcyclothiopropane, 11 mg of tetrabutylammonium chloride and 1.5 mL of N,N-dimethylacetamide to the first polymer block and mix them evenly. React at 70 °C for 12 h. Pour the reaction solution into methanol, centrifuge to obtain the precipitate, and vacuum dry the precipitate to obtain multi-block stereoregular polysulfide.

[0051] Test methods Number-average molecular weight and molecular weight distribution were determined by gel permeation chromatography with tetrahydrofuran as the mobile phase, a flow rate of 1.0 mL / min, and a column temperature of 40 °C. The system was calibrated using a narrow-distribution polystyrene standard with a known molecular weight, and a standard curve was plotted. The number-average molecular weight of the polymer was calculated based on this standard curve. Molecular weight distribution = weight-average molecular weight / number-average molecular weight.

[0052] Glass transition temperature test: Differential scanning calorimetry (DSC) was used. Approximately 5 mg of polymer samples from the examples and comparative examples were weighed and placed in a standard aluminum crucible. Under nitrogen atmosphere protection, the temperature was scanned from -80°C to 150°C at a constant heating rate of 10°C / min. The glass transition temperature on the obtained DSC curve was taken as the temperature value corresponding to the midpoint of the heat flow change stage.

[0053] Tensile strength and elongation at break tests: According to the test methods of national standard GB / T528-2009, the polymer samples of the examples and comparative examples were made into sheets of a specified thickness by hot pressing and cut into standard dumbbell-shaped strips. Using a universal testing machine, the strips were stretched at a constant tensile rate of 500 mm / min at room temperature (23±2℃) until they broke. The tensile strength was taken as the maximum stress value on the stress-strain curve, and the elongation at break was taken as the percentage of strain at the time of strip breakage. The specific results are shown in Table 1 below.

[0054] Table 1

[0055] In Comparative Example 1, since the first sulfur-containing monomer was not added, the product only exhibited a glass transition temperature (-48°C) corresponding to the soft segment of polybutyl acrylate, and its tensile strength (5.2 MPa) was much lower than that of Example 1. This indicates that the first sulfur-containing monomer is a key component for achieving efficient, stereoselective anionic ring-opening polymerization conversion from polythiocarbonate ends to cyclothiopropane monomers. Without this component, it is impossible to successfully construct stereoregular polysulfide hard segments, resulting in the final material failing to achieve the expected reinforcing effect and high thermal properties.

[0056] In Comparative Example 2, although a first sulfur-containing monomer was added, a quaternary ammonium salt catalyst was not used. The results showed that the product molecular weight increased only slightly (Mn: 41,200), and only the glass transition temperature of the polybutyl acrylate soft segment (-46°C) was detected. The mechanical strength (8.7 MPa), while improved, was far lower than in Example 1. This indicates that in the absence of a quaternary ammonium salt catalyst, the ring-opening polymerization efficiency of cyclothiopropane monomers is extremely low, and it is impossible to form stereoregular hard segments with independent phase regions. Therefore, a quaternary ammonium salt catalyst is an essential component to ensure the efficient and controllable execution of the second-step anionic ring-opening polymerization, thereby obtaining a high-performance multi-block structure.

[0057] Comparative Example 3, which involved adding all monomers and reagents simultaneously, resulted in a product with a wide molecular weight distribution and only a broad glass transition temperature, leading to poor mechanical properties. This indicates that the simultaneous existence of RAFT radical polymerization and anionic ring-opening polymerization of cyclothiopropane can interfere with each other, causing uncontrolled initiation and chain growth, resulting in copolymers with random structures and poor performance. This demonstrates that the stepwise synthesis method employed in this invention, which involves first completing the first step of radical polymerization and then initiating the second step of stereoselective anionic polymerization in situ, is essential for obtaining multi-block structures with well-defined sequences and microphase separation.

[0058] Comparative Example 4 uses a traditional method of stepwise synthesis and intermediate purification. The molecular weight and microstructure of its final product are similar to those of the product in Example 1. However, this process introduces additional cumbersome operations such as precipitation, filtration, drying, and redissolution, which significantly prolongs the entire synthesis cycle and reduces the overall yield due to unavoidable transfer and processing losses. The synthesis method provided by this invention can greatly simplify the process, shorten the production time, and improve the utilization rate of raw materials while ensuring the efficient formation of multi-block stereoregular structures.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a multi-block stereoregular polysulfide, characterized in that, Includes the following steps: (1) Butyl acrylate, free radical initiator, polythiocarbonate chain transfer agent, first sulfur-containing monomer and N,N-dimethylacetamide are mixed and subjected to free radical polymerization at 60~80℃ for 8~16h under an inert atmosphere to form the first polymer block; (2) Add the second sulfur-containing monomer and quaternary ammonium salt catalyst to the reaction system of step (1), and carry out anionic ring-opening polymerization reaction at 60~80℃ for 12h to form the second polymer block, thereby obtaining the multi-block stereoregular polysulfide; In step (2), the mass ratio of the second sulfur-containing monomer added to the first sulfur-containing monomer in step (1) is (10-30):1, and the mass ratio of the quaternary ammonium salt catalyst added to the first sulfur-containing monomer in step (1) is (1.0-2.0):

1.

2. The method for preparing multi-block stereoregular polysulfide according to claim 1, characterized in that, The first sulfur-containing monomer is dibenzo[c,e]oxazo-5(7H)-thione.

3. The method for preparing multi-block stereoregular polysulfide according to claim 1, characterized in that, The second sulfur-containing monomer is at least one of 2-phenoxymethylcyclothiopropane and 2-butoxymethylcyclothiopropane, which have a single configuration.

4. The method for preparing multi-block stereoregular polysulfide according to claim 1, characterized in that, The polythiocarbonate chain transfer agent is at least one of bis(methoxycarbonylmethyl)trithiocarbonate and 4-cyano-4-(((phenylethylthio)thiocarbonyl)thio)valerate.

5. The method for preparing multi-block stereoregular polysulfide according to claim 1, characterized in that, The quaternary ammonium salt catalyst is tetrabutylammonium chloride.

6. The method for preparing multi-block stereoregular polysulfide according to claim 1, characterized in that, The free radical initiator is azobisisobutyronitrile.

7. The method for preparing multi-block stereoregular polysulfide according to claim 1, characterized in that, In step (1), the mass ratio of the first sulfur-containing monomer, butyl acrylate, free radical initiator, polythiocarbonate chain transfer agent, and N,N-dimethylacetamide is 1:(20-50):(0.01-0.05):(0.2-0.5):(100-500).

8. A multi-block stereoregular polysulfide, characterized in that, It is prepared by the method according to any one of claims 1 to 7.

9. The multi-block stereoregular polysulfide according to claim 8, characterized in that, The polysulfide has a number average molecular weight of 20,000 to 150,000 and a molecular weight distribution of 1.2 to 2.

5.

10. The application of the multi-block stereoregular polysulfide according to claim 8 or 9 in the preparation of engineering plastics, special elastomers and functional coating materials.

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