Preparation method of crystalline polydisulfide material and solvent-free recovery method thereof
Crystalline polydisulfide materials were prepared by organic acid catalysis and annealing, and solvent-free recovery was achieved by combining heat treatment, which solved the problems of high energy consumption and environmental pollution, and achieved a high-efficiency and low-energy polymer recovery effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- EAST CHINA UNIV OF SCI & TECH
- Filing Date
- 2024-11-14
- Publication Date
- 2026-07-31
AI Technical Summary
Existing synthetic polymer recycling processes are energy-intensive and use large amounts of solvents, and traditional methods are harmful to the environment, making it difficult to achieve low-energy consumption and high-efficiency closed-loop chemical recyclability.
Crystalline polydisulfide materials were prepared using organic acid catalysis and annealing processes, and then depolymerized and recovered into monomers under solvent-free conditions through heat treatment, simplifying the recycling process.
It achieves efficient and low-energy solvent-free recovery of polymers to monomers, with a monomer recovery rate of up to 90%, which meets the requirements of green chemistry and reduces carbon emissions and environmental impact.
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Figure CN119708490B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer materials chemistry technology, specifically, it relates to a method for preparing crystalline polydisulfide materials and a solvent-free recovery method thereof. Background Technology
[0002] The recycling of most synthetic polymers remains a major challenge. Currently, significant efforts have been made using "near-equilibrium" design strategies, particularly in lactone-based polyesters, to achieve a delicate balance between polymerization and depolymerization capabilities by precisely controlling the ring strain of the lactone monomers. While this molecular engineering strategy is versatile, the near-equilibrium nature of the reaction typically reduces polymerization efficiency, thus requiring very low temperatures to achieve high monomer conversion rates. Furthermore, the recycling process relies on entropy as a driving force, still consuming substantial amounts of energy or solvents. Therefore, designing recyclable synthetic polymers with closed-loop chemistry that minimize energy consumption and maximize environmental benefits throughout their entire lifecycle remains a fundamental challenge.
[0003] Currently, recyclable polymers mainly rely on entropy as the driving force for depolymerization, thus requiring high temperatures and / or solvent dilution. The former consumes energy, while the latter generates solvent waste. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing crystalline polydisulfide materials.
[0005] Another objective of this invention is to provide a solvent-free supramolecular recovery method for crystalline polydisulfide materials prepared by the aforementioned method. This method employs a simple and effective recovery process, using a simple heating treatment to depolymerize the crystalline polydisulfide material into monomers, achieving a high recovery yield and realizing solvent-free, efficient depolymerization and recovery of polydisulfide materials. The preparation and recovery processes are mild and the method is simple.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] In a first aspect, the present invention provides a method for preparing a crystalline polydisulfide material, comprising the following steps:
[0008] The disulfide five-membered ring monomer with a molar ratio of 1:0.8 to 5 (preferably 1:2.7) is stirred evenly with an organic acid and allowed to stand for 0.5 to 24 hours (preferably 1 hour) to react. The organic acid is removed by vacuuming. Then, the mixture is soaked in an organic solvent and vacuum dried to obtain an amorphous polydisulfide material. After annealing, a crystalline polydisulfide material is prepared.
[0009] The disulfide five-membered ring monomer is selected from one of the following structures:
[0010]
[0011] R1 is selected from
[0012] R2 is selected from H, -NH2, C1 to C10 alkyl groups,
[0013] R3 is selected from H, -NH2, C1 to C10 alkyl groups, and -B(OH)2;
[0014] R4 is selected from H, -NH2, C1 to C10 alkyl groups, and -B(OH)2;
[0015] R5 is selected from H, -NH2, C1 to C10 alkyl groups, and -B(OH)2;
[0016] R6 is selected from H, -NH2, C1 to C10 alkyl groups, and -B(OH)2;
[0017] R7 is selected from H, -NH2, C1 to C10 alkyl groups, and -B(OH)2;
[0018] R8 is selected from H, -B(OH)2;
[0019] R9 is selected from H, -B(OH)2;
[0020] R 10 Selected from H, -B(OH)2;
[0021] R 11 Selected from H, -B(OH)2;
[0022] R 12 Selected from H, -B(OH)2;
[0023] R 13 Selected from H, C1 to C5 alkyl groups;
[0024] R 14 Selected from C1 to C5 alkyl groups
[0025] R 15 Selected from hydrogen and -NH2;
[0026] R 16 Selected from C1 to C5 alkyl groups, -CHClCH3;
[0027] R 17 Selected from hydrogen,
[0028] The organic acid is selected from at least one of the following: trifluoroacetic acid, trichloroacetic acid, perfluorobutyric acid, perfluorooctanoic acid, chloroacetic acid, trimethylbenzenesulfonic acid, trifluoromethanesulfonic acid, dihaloacetic acid, dichloroacetic acid, monochloroacetic acid, oxalic acid, phosphoric acid, formic acid, benzoic acid, acetic acid, propionic acid, succinic acid, citric acid, lactic acid, fumaric acid, tartaric acid, malic acid, acrylic acid, butyric acid, octanoic acid, adipic acid, oxalic acid, malonic acid, succinic acid, maleic acid, benzoic acid, phenylacetic acid, phthalic acid, terephthalic acid, valeric acid, hexanoic acid, decanoic acid, stearic acid, palmitic acid, and acrylic acid.
[0029] Most preferably, the disulfide five-membered ring monomer is selected from one of the following structures:
[0030]
[0031] The organic solvent is selected from alcohol-based organic solvents, preferably methanol.
[0032] The annealing conditions are as follows: annealing at a temperature of 100-140℃ (preferably 120℃ or 135℃) for 1-6 hours (preferably 2 hours).
[0033] A second aspect of the present invention provides a solvent-free supramolecular recovery method for crystalline polydisulfide materials prepared by the method described above, comprising the following steps:
[0034] The crystalline polydisulfide material prepared by the method is heated to a temperature of 80–140°C (preferably 120°C or 135°C) for a time of 4–72 h (preferably 10 h, 12 h, 36 h, 40 h, or 48 h) to prepare a disulfide five-membered ring monomer.
[0035] The disulfide five-membered ring monomer is selected from one of the following structures:
[0036]
[0037] R1 is selected from
[0038] R2 is selected from H, -NH2, C1 to C10 alkyl groups,
[0039] R3 is selected from H, -NH2, C1 to C10 alkyl groups, and -B(OH)2;
[0040] R4 is selected from H, -NH2, C1 to C10 alkyl groups, and -B(OH)2;
[0041] R5 is selected from H, -NH2, C1 to C10 alkyl groups, and -B(OH)2;
[0042] R6 is selected from H, -NH2, C1 to C10 alkyl groups, and -B(OH)2;
[0043] R7 is selected from H, -NH2, C1 to C10 alkyl groups, and -B(OH)2;
[0044] R8 is selected from H, -B(OH)2;
[0045] R9 is selected from H, -B(OH)2;
[0046] R 10 Selected from H, -B(OH)2;
[0047] R 11 Selected from H, -B(OH)2;
[0048] R 12 Selected from H, -B(OH)2;
[0049] R 13 Selected from H, C1 to C5 alkyl groups;
[0050] R 14 Selected from C1 to C5 alkyl groups
[0051] R 15 Selected from hydrogen and -NH2;
[0052] R 16 Selected from C1 to C5 alkyl groups, -CHClCH3;
[0053] R 17 Selected from hydrogen,
[0054] Most preferably, the disulfide five-membered ring monomer is selected from one of the following structures:
[0055]
[0056] The innovation of this invention lies in the use of organic acid to catalyze the polymerization of disulfide five-membered ring monomers. The polymer is then purified and further annealed to obtain high-performance crystalline polydisulfide materials. The crystalline polydisulfide materials prepared by this method can achieve chemical recovery from polymer to monomer under high-temperature solvent-free conditions.
[0057] The reaction formula is shown below:
[0058]
[0059] n is an integer from 4 to 14.
[0060] By adopting the above technical solution, the present invention has the following advantages and beneficial effects:
[0061] This invention utilizes a simple organic acid catalysis and assisted annealing process to prepare crystalline polydisulfide materials. The solvent-free recovery process for this type of polydisulfide material offers advantages such as simplicity, low energy consumption, low carbon emissions, and no waste gas or liquid generation. The organic acid catalysis strategy and annealing process proposed in this invention successfully transform amorphous polydisulfide materials into crystalline polydisulfide materials. Previously, thermally polymerized polythiooctanoic acid (Polythioctic acid) materials were amorphous polymer networks, and the chemical recovery process to monomers often required catalysts and large amounts of solvents, resulting in complex and cumbersome post-processing. This invention proposes a solvent-free supramolecular recovery method for crystalline polydisulfide materials, which can directly depolymerize and recover crystalline polydisulfide materials into monomers through heat treatment without the addition of catalysts or solvents, achieving a monomer recovery yield of over 90%. The reaction process is simple, the preparation is rapid, and it meets the requirements of green chemistry.
[0062] The preparation and recycling process of the crystalline polydisulfide material proposed in this invention is low-cost and highly efficient, meeting the dual-carbon development strategy goals and possessing practical industrial feasibility.
[0063] This invention relates to an organic acid-catalyzed method for preparing crystalline polydisulfide materials and a heat treatment recovery method. It features solvent-free, environmentally friendly, low energy consumption, high monomer recovery yield, and low carbon footprint, and is industrially feasible.
[0064] This invention involves heat-treating crystalline polydisulfide materials under mild heating conditions, resulting in the spontaneous depolymerization and recovery of the polymer into monomers. This process features high quantitative recovery rates (over 90%), high monomer purity, low cost, and the elimination of the need for solvents and catalysts in the recovery process. Life cycle assessments demonstrate that this invention offers significant environmental benefits compared to traditional solvent-based chemical recovery methods. Attached Figure Description
[0065] Figure 1 This is a schematic diagram of polarized light microscope images of amorphous polythiooctamide and crystalline polythiooctamide in Example 1.
[0066] Figure 2 This is a schematic diagram of X-ray diffraction analysis of amorphous polythiooctamide and crystalline polythiooctamide in Example 1.
[0067] Figure 3 This is a schematic diagram of the differential scanning calorimetry (DSC) spectra of amorphous polythiooctamide and crystalline polythiooctamide in Example 1.
[0068] Figure 4 This is a schematic diagram of the rheological test curves of amorphous polythiooctamide and crystalline polythiooctamide in Example 1.
[0069] Figure 5 This is a schematic diagram of matrix-assisted laser desorption / ionization time-of-flight mass spectrometry analysis of amorphous polythiooctamide and crystalline polythiooctamide in Example 1.
[0070] Figure 6 This is a schematic diagram of the nanoindentation test results of crystalline polythioctin in Example 1.
[0071] Figure 7 This is a schematic diagram of the appearance of the crystalline polythiooctamide material and the monomers obtained from solvent-free supramolecular recovery in Example 1.
[0072] Figure 8 This is a schematic microscopic photograph of the raw material thioctin monomer in Example 1 and the thioctin monomer obtained by the solvent-free supramolecular recovery method.
[0073] Figure 9 This is a schematic diagram comparing the proton NMR spectra of the raw thioctin monomer and the thioctin monomer obtained by the solvent-free supramolecular recovery method.
[0074] Figure 10 This is a schematic diagram comparing the Raman spectra of the raw material thiocamide monomer and the thiocamide monomer obtained through a solvent-free supramolecular recovery method. Detailed Implementation
[0075] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.
[0076] Example 1
[0077] A method for preparing a crystalline polydisulfide material includes the following steps:
[0078]
[0079] Thioctamide (4.88 mmol, 1 g) was placed in a polytetrafluoroethylene mold, and trifluoroacetic acid (13 mmol, 1 mL) was added with a pipette and stirred until homogeneous. The mixture was allowed to stand for 1 h to obtain a yellow, transparent, viscous substance. The trifluoroacetic acid was then dried under vacuum to obtain a yellow, gel-like polythiocamide material with a certain viscosity. The yellow gel-like polythiocamide material was then immersed in 50 mL of methanol for 1 h to remove residual trifluoroacetic acid and monomers / oligomers. The mixture was then dried under vacuum at room temperature to obtain a white, tough, amorphous polythiocamide material. The material was annealed at 120 °C for 2 h, and the amorphous polymer gradually transformed into a crystalline polymer. 0.85 g of yellow, hard, crystalline polythiocamide material (polymer 1) was prepared, where n is an integer from 4 to 14.
[0080] Figure 1The image shows a polarized light microscope photograph of amorphous polythiooctamide and crystalline polythiooctamide in Example 1. It can be clearly seen from the image that the crystalline morphology of amorphous polythiooctamide changes after annealing, eventually forming spherulite regions. Figure 2 This is a schematic diagram of X-ray diffraction analysis of amorphous polythiooctamide and crystalline polythiooctamide in Example 1. As can be seen from the figure, the diffraction peaks in the X-ray diffraction pattern before the annealing process are relatively broad, which are typical characteristic peaks of amorphous polymers. After the annealing process, the polymer network forms crystalline regions, and obvious X-ray diffraction peaks appear in the pattern, proving that crystalline polythiooctamide is obtained.
[0081] Figure 3 This is a schematic diagram of the differential scanning calorimetry (DSC) spectra of amorphous polythiooctamide and crystalline polythiooctamide in Example 1. The results show that before annealing, polythiooctamide is an amorphous polymer material with a glass transition temperature of 19°C. After annealing, the polymer network structure changes, and the amorphous polymer is transformed into a crystalline polymer material, exhibiting a crystalline peak at 61.2°C. Figure 4 This is a schematic diagram of the rheological test curves of amorphous polythiooctamide and crystalline polythiooctamide in Example 1. As can be seen from the figure, the storage modulus of amorphous polythiooctamide at room temperature is higher than its loss modulus, indicating that the internal structure of this material can maintain its shape and has minimal energy loss when subjected to external forces, suggesting a glassy state. At approximately 30°C, the material undergoes a glass transition, transforming from a glassy state to a highly elastic state. Between 60°C and 120°C, it exhibits a rubber plateau region, transitioning to a highly elastic state, with both the storage modulus and loss modulus exceeding 10. 4 The Pa value indicates that the material has good thermal stability. After annealing, the glass transition temperature of crystalline polythioctin with a spherulitic structure increases significantly, reaching approximately 60℃. Its storage modulus is higher than its loss modulus below 120℃, exhibiting solid-state characteristics, indicating that crystalline polythioctin has excellent thermal stability.
[0082] Figure 5 This is a schematic diagram of matrix-assisted laser desorption / ionization time-of-flight mass spectrometry analysis of amorphous polythiooctamide and crystalline polythiooctamide in Example 1. As can be seen from the figure, after the annealing process, polythiooctamide changes from a cyclic polymer to a linear polymer. The n in the structure of amorphous polythiooctamide is 4 to 14, and the n in the structure of crystalline polythiooctamide is 4 to 10. Figure 6 This is a schematic diagram of the nanoindentation test results of crystalline polythioctinamide in Example 1. Under constant load control test conditions, the modulus of the crystalline polythioctinamide material is 2.90±0.08GPa, the hardness is 0.11±0.05GPa, and the test curve has good performance repeatability.
[0083] Application Example 1
[0084] A solvent-free supramolecular recovery method for polythiooctamide materials prepared by the above method includes the following steps:
[0085]
[0086] 1g of yellow hard crystalline polythiocamide material (polymer 1) was heated at 120℃ for 12h, and the polythiocamide was gradually converted into thiocamide monomer, yielding 0.9g of thiocamide monomer. The recovery rate of thiocamide monomer was 90%.
[0087] Figure 7 The image shows a schematic diagram of the appearance of the crystalline polythioctin material of Example 1 and the monomer obtained by the solvent-free supramolecular recovery method. The yellow translucent polythioctin gradually transforms into an opaque yellow thioctin monomer. Figure 8 The image shows a schematic diagram of a microscope image of the raw material thioclamamide monomer in Example 1 and the thioclamamide monomer obtained by the solvent-free supramolecular recovery method. The results show that the two have similar plate-like crystal morphologies. Figure 9 The figure shows a comparison of the proton NMR spectra of the raw material thioclamamide monomer and the thioclamamide monomer obtained by the solvent-free supramolecular recovery method. As can be seen from the figure, after the solvent-free supramolecular recovery treatment, the polymer characteristic peaks are reduced and the monomer characteristic peaks are obvious. This result indicates that the polythioclamamide material is efficiently converted into thioclamamide monomer with a monomer conversion rate of up to 90%. Figure 10 This is a schematic diagram comparing the Raman spectra of the raw thiocamide monomer and the thiocamide monomer obtained through a solvent-free supramolecular recovery method. The results show that the recovered monomer has the same Raman shift as the original monomer, indicating that the polythiocamide material is transformed into thiocamide monomer with high monomer purity.
[0088] Examples 2-12
[0089] The type of disulfide five-membered ring monomer was changed, while other reaction steps and ratios remained the same as in Example 1, as shown in Table 1:
[0090] Table 1
[0091]
[0092]
[0093] Comparative Example 1
[0094] Existing methods for recycling polydisulfide materials mainly employ solvent recovery methods (Zhang, Q., Deng, Y., Shi, C.-Y., Feringa, BL, Tian, H., & Qu, D.-H. Dual closed-loop chemical recycling of synthetic polymers by intrinsically reconfigurable poly(disulfides). Matter, 2021, 4(4), 1352–1364), which degrade the polymer in an alkaline aqueous solution and obtain the original monomers through acidification separation.
[0095] 1g of polymer sample was added to 15mL of 0.5M NaOH aqueous solution and stirred continuously until the polymer was completely degraded. The mixture was filtered to remove the formed metal hydroxide precipitate. Subsequently, the filtrate was slowly acidified to pH 3-4 using 1M HCl aqueous solution, yielding precipitated TA monomer as a yellow powder. The monomer recovery rate was 60%-80%. This method requires degradation with an alkaline solution followed by acidification to obtain the monomer. This solvent recovery method involves the use of large amounts of strong acid and strong alkali solutions, which is highly harmful to the environment and results in high wastewater treatment costs, posing potential problems in environmental protection.
[0096] This invention utilizes heat recovery monomers, achieving a monomer recovery rate of up to 90%, making it green, environmentally friendly, and energy-efficient.
[0097] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A method for preparing a crystalline polydisulfide material, characterized in that, Includes the following steps: The disulfide five-membered ring monomer with a molar ratio of 1:0.8~5 was stirred with an organic acid and allowed to stand for 0.5~24 h to remove the organic acid. Then it was soaked in an organic solvent and vacuum dried to obtain an amorphous polydisulfide material. After annealing, a crystalline polydisulfide material was prepared. The organic acid is selected from trifluoroacetic acid and formic acid; The organic solvent is selected from methanol; The annealing conditions are as follows: annealing at a temperature of 100~140 ℃ for 1~6 h; The disulfide five-membered ring monomer is selected from one of the following structures: 。 2. The method for preparing crystalline polydisulfide material according to claim 1, characterized in that, The annealing conditions are as follows: annealing at a temperature of 120 ℃ or 135 ℃ for 2 h.
3. A solvent-free supramolecular recovery method for crystalline polydisulfide materials prepared by the method of claim 1 or 2, characterized in that, Includes the following steps: The prepared crystalline polydisulfide material was heated to a temperature of 80–140 °C for 4–72 h to obtain a disulfide five-membered ring monomer.
4. The solvent-free supramolecular recovery method for crystalline polydisulfide materials according to claim 3, characterized in that, The heating temperature is 120 ℃ or 135 ℃.
5. The solvent-free supramolecular recovery method for crystalline polydisulfide materials according to claim 3, characterized in that, The heating time is selected from 10 h, 12 h, 36 h, 40 h, and 48 h.