A method for preparing a salt of polythioic acid and polythioic acid in an aqueous phase

Abstract

The application discloses a method for preparing polythioctic acid salt and polythioctic acid in an aqueous phase, and belongs to the field of degradable bio-based polymer materials. In the method, thioctic acid salt is used as a monomer, the thioctic acid salt is dissolved in water, a water-soluble initiator is added, and ring-opening polymerization is realized under open air and normal temperature and pressure stirring to prepare a polymer polythioctic acid salt. Then, the pH of the polythioctic acid salt solution is adjusted to be acidic to prepare polythioctic acid. The initiator used in the method is an inorganic salt, a metal organic salt or a Fenton-like reagent. The method uses water as a reaction medium, has mild reaction conditions, does not need heating and inert gas protection, and can realize polymerization in a short time. The method has the characteristics of simple operation, environmental friendliness and good applicability. The obtained polythioctic acid salt can be widely applied to the fields of high-end emerging materials such as biological medicines, green photoresists, degradable functional coatings, self-repairing materials and reconfigurable micro-nano processing materials.

Description

Technical Field

[0001] This invention relates to the field of biodegradable bio-based polymer materials, and more specifically to a method for preparing polythiooctanoate and polythiooctanoic acid in an aqueous phase. Background Technology

[0002] High-performance polymer materials are core foundational materials for strategic emerging industries such as integrated circuit manufacturing, high-end medical devices, biomanufacturing, advanced functional coatings, and green manufacturing. They play a crucial supporting role in the industrial upgrading and independent and controllable development of high-end manufacturing, biomedicine, and electronic information (Xia et al., Chinese Engineering Science, 2024, 26(3): 1-9). In the field of semiconductor micro-nano processing, photoresists and supporting functional materials directly determine the processing precision, process stability, and level of independent control of the industrial chain in microelectronics manufacturing. In the field of high-end biomedicine, functional polymer materials that combine biocompatibility, biodegradability, and environmental friendliness are core components for the iterative upgrading of core technologies such as tissue repair, drug delivery, medical adhesives, injectable formulations, and surface functionalization of implantable devices.

[0003] Among many polymer materials, polylipoic acid (PPA) is a biodegradable, multifunctional polymer material synthesized from the ring-opening polymerization of natural bio-derived small molecule lipoic acid. The PPA backbone contains dynamic disulfide bonds, giving this type of material properties such as degradability, reversible responsiveness, dynamic exchange, and self-healing (Wang et al., Adv. Funct. Mater. 2025, e25297; Palet al., Prog. Polym. Sci. 2025, 160, 101920). Simultaneously, the carboxyl groups in the side chains endow the material with broad adhesive and bonding properties. Furthermore, lipoic acid also possesses anti-inflammatory and antioxidant bioactivities (Ma et al., Biomacromolecules 2026, 27, 3444). 3466). Therefore, polythioctic acid has broad application potential in fields such as erasable photoresists, erasable and reconfigurable precision functional materials, biodegradable adhesives, self-healing functional materials, biomedical materials, drug carriers, and dynamic network materials (Huang et al., Adv. Funct. Mater. 2024, 2413542; Maet al., Matter 2024, 7, 4046-4058; Dang et al., Adv. Mater. 2024, 36,2406967).

[0004] Currently, the preparation of polythiooctanoic acid (PPA) generally relies on toxic, flammable, and volatile organic solvents, and requires ring-opening polymerization under harsh conditions such as high temperature, light exposure, strong acid, inert gas protection, or specialized electrochemical equipment (e.g., CN108484923B; CN114058014B; CN113061263B; Fang et al., Angew. Chem. Int. Ed. 2025, e202506724; Zhang et al., J. Am. Chem. Soc. 2019, 141, 12804-12814; CN113214482B; CN119925673A; Wang et al., Angew. Chem. Int. Ed. 2023, 62, e202215329; Liu et al., J. Am. Chem. Soc. 2019, 141, 17075 17080). Existing preparation methods suffer from high energy consumption, complex processes, and high production costs (Zhang et al., Sci. Adv. 2018,4, eaat8192; Fang et al., Nature 2023, 619, 293-299; Shi et al., ACS Appl. Mater. Interfaces 2021, 13, 44860-44867; Machado et al., Nature 2024, 629,1069-1074; CN117587425A; Du et al., J. Am. Chem. Soc. 2023, 145, 27788-27799; CN109401336B; CN115322375A), making it difficult to meet the core requirements of low-carbon, safe, and green material preparation processes in high-end precision manufacturing and biomedical fields. In particular, the use of large amounts of organic solvents and multi-step post-processing processes can easily lead to problems such as solvent residue, impurity pollution and waste discharge, which greatly limits its application in fields such as biomedicine and semiconductor precision processing.

[0005] With the growing demand for green and sustainable development, developing green polymerization methods using water as the reaction medium has become an important direction for the preparation of polythiooctanoic acid (PoTA) functional polymers. To meet the contemporary requirement of aqueous-phase preparation of PoTA, existing technologies mainly include:

[0006] 1) Hydrophobic polythiooctanoic acid (PPA) is first prepared in an organic solution, and then PTA is prepared by treatment with an alkaline aqueous solution to improve water solubility. However, the disulfide bonds in the PTA backbone are prone to breakage or depolymerization in an alkaline environment, which leads to decreased system stability, reduced molecular weight and degraded material properties, making it difficult to obtain structurally stable and performance-controllable water-soluble PTA (Zhang et al., Matter 2021, 4, 1352-1364).

[0007] 2) Polythioctic acid (PPA) is prepared by dispersing thioctic acid monomers in the oil phase of an oil-in-water emulsion formed by a surfactant in an aqueous solution (Morris et al., J. Am. Chem. Soc. 2024, 146, 30662). (30667). Although the polymerization is achieved in an aqueous phase, the preparation process still involves organic solvents, and the resulting polythiooctanoic acid is difficult to purify when dispersed in an emulsion.

[0008] A few existing technologies disclose technical solutions for the preparation of polythiooctanoate by thermal polymerization in alkaline aqueous solutions (Zhang et al., Matter 2021, 4, 1352-1364). However, heating polymerization often triggers depolymerization simultaneously, and studies have shown that the stronger the alkalinity, the faster the depolymerization. In the preparation of polythiooctanoate, the conversion rate of traditional thermal polymerization is only 30–40%, and the molecular weight is only 5–30 kg / mol, which is insufficient to meet the needs of industrial applications.

[0009] Meanwhile, polythioctic acid (Polythioctic Acid) has specific molecular weight requirements in different application fields: in the field of biomedical materials, the Polythioctic Acid-Metal Coordination Hybrid Network requires... Mn The molecular weight ranges from 1 to 60 kg / mol; in the field of biodegradable copolymers, the molecular weight needs to reach the order of hundreds of kg / mol to meet the mechanical performance requirements; in the field of functional materials such as adhesives and self-healing coatings, a sufficiently high molecular weight is also required to ensure network integrity and mechanical strength.

[0010] Therefore, there is an urgent need in this field to provide a completely green aqueous polymerization process that can achieve the efficient preparation of polythiooctanoic acid under mild conditions. Summary of the Invention

[0011] In view of this, the present invention provides a green polymerization method for the mild, convenient, and efficient preparation of polythiooctanoic acid and polythiooctanoate in aqueous solution under open air conditions. The present invention uses water as a solvent and a water-soluble initiator to rapidly polymerize thiooctanoate monomers in an alkaline environment under normal pressure and open air to prepare water-soluble polythiooctanoate. Subsequently, the pH of the polythiooctanoate aqueous solution is adjusted to acidity to obtain polythiooctanoic acid. The polythiooctanoic acid obtained by the present invention has significant application potential in core areas such as photoresist erasure and micro / nano-fabrication functional materials, including biodegradable, removable protective layers, and functional coatings.

[0012] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing polythiooctanoate in aqueous phase includes the following steps: (1) Monomer dissolution: The thioctic acid monomer is dissolved in an alkaline aqueous solution to obtain an alkaline aqueous solution of thiocate salt; (2) Aqueous phase polymerization: A water-soluble initiator is added to an alkaline aqueous solution of thiooctanoate, and the aqueous phase monomer ring-opening polymerization is carried out under normal temperature, normal pressure and open air conditions to obtain a water-soluble polythiooctanoate aqueous solution.

[0013] The resulting water-soluble polythiooctanoate has the structure shown in Formula I:

[0014] Formula I: Polythiooctanoate structural formula In Equation I, M + for Na + K + or NH4 + n takes the value of a positive integer from 10 to 1000.

[0015] Furthermore, the solute in the alkaline aqueous solution in step (1) is any one of sodium hydroxide, sodium carbonate, sodium bicarbonate, or ammonia.

[0016] Furthermore, the pH of the alkaline aqueous solution is 7.4-9.0.

[0017] Furthermore, the molar ratio of thioctic acid salt to initiator in step (2) is 100:1-5:1.

[0018] Furthermore, the concentration of thioctic acid salt in the aqueous solution of thioctic acid salt is 0.005-0.4 mol / L.

[0019] Furthermore, the initiator is any one of inorganic salts, organometallic salts, and Fenton-like reagents.

[0020] Preferably, the inorganic salt is any one of sodium manganate, potassium manganate, sodium chlorate, potassium chlorate, sodium iodate, potassium iodate, sodium trioxane ferrate, potassium trioxane ferrate, and hexaminecobalt. The organometallic salt is EDTA and Fe. 3+ and Co 3+ The formed stable complex; More preferably, EDTA and Fe 3+ or Co 3+ In the stable complex formed, EDTA and Fe 3+ or Co 3+ The molar ratio is 1:1.

[0021] The Fenton-like reagent is composed of a water-soluble divalent metal salt and hydrogen peroxide, wherein the divalent metal salt is any one of divalent iron salt, divalent copper salt, divalent cobalt salt, and divalent nickel salt.

[0022] The amount of hydrogen peroxide used in the Fenton-like reagent is higher than the amount of divalent metal salt.

[0023] Furthermore, in step (2), the reaction time for the ring-opening polymerization of the aqueous monomer is 1-30 min, and the reaction stirring rate is 100-1000 rpm.

[0024] This invention also provides a method for preparing polythiooctanoic acid in an aqueous phase, wherein the water-soluble polythiooctanoic acid aqueous solution prepared by the above method comprises the following steps: Add an acidic aqueous solution to the obtained water-soluble polythiooctanoate aqueous solution to adjust the pH of the solution to acidic, and you can obtain polythiooctanoic acid.

[0025] The resulting polythiooctanoic acid has the structure shown in Formula II:

[0026] Formula II: Polythiooctanoic acid structural formula In Equation II, n takes the value of a positive integer from 10 to 1000.

[0027] Furthermore, the solute in the acidic aqueous solution is hydrochloric acid; The pH of the acidic aqueous solution is 3.5-4.5.

[0028] This invention also provides a reaction process for the aqueous preparation of polythiooctanoate and polythiooctanoic acid, as shown in Formula III:

[0029] Formula III: Aqueous phase polymerization reaction of thiocate, polythiocate and polythioctic acid In Formula III, M + for Na + K + or NH4 + n takes the value of a positive integer from 10 to 1000.

[0030] The beneficial effects of this invention are as follows: (1) The present invention uses thiocate as monomer and alkaline aqueous solution as solvent to prepare polythioctic acid and polythiocate by ring-opening polymerization initiated by water-soluble initiator. The polymerization method of the present invention is simple to operate and environmentally friendly.

[0031] (2) The reaction conditions of the present invention are extremely mild, and the efficient preparation of polythioctic acid and polythiocate can be achieved under normal temperature, normal pressure and open air conditions.

[0032] (3) The present invention uses low-toxicity inorganic salts, organometallic salts and Fenton-like reagents as water-soluble initiators to achieve efficient aqueous phase polymerization of thioctic acid salts through a free radical-dominated chain initiation mechanism. The monomer conversion rate of the present invention can reach 75-80%, and high molecular weight polythioctic acid / polythioctic acid salts with a number average molecular weight of up to 70 kg / mol can be obtained.

[0033] (4) This invention uses thiocate as a monomer, which fully demonstrates the utilization of thioctic acid, a natural bioactive molecule. Water-soluble polythiocate has good biocompatibility and biodegradability, and has broad application prospects in the biomedical field. Attached Figure Description

[0034] Figure 1 The image shows the physical samples of sodium polythiooctanoate and polythiooctanoic acid prepared by aqueous phase polymerization in Example 1. Figure 2 The above are the 1H NMR spectra of the thioctic acid monomer and the prepared sodium polythiocate and polythioctic acid in Example 1. Figure 3 This is a gel permeation chromatogram of the polythiooctanoic acid obtained in Example 1; Figure 4 This is a matrix-assisted time-of-flight mass spectrum of the polythiooctanoic acid obtained in Example 1; Figure 5 This is a gel permeation chromatogram of the polythiooctanoic acid obtained in Example 18; Figure 6 The image shows a gel permeation chromatogram of the polythiooctanoic acid obtained in Example 20. Figure 7 The image shows the electron paramagnetic resonance spectrum of the Fenton reaction system in Example 20. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1 (1) Dissolve 206.3 mg of thioctic acid monomer in 10.0 mL of NaOH aqueous solution with pH 7.4.

[0037] (2) 19.8 mg of sodium iodate (NaIO3) initiator was added to an aqueous solution of sodium thiocate, controlling the molar concentration of sodium thiocate monomer to be 0.1 mol / L, and the molar ratio of monomer to initiator to be 10:1. The solution was stirred at 500 rpm for 30 min at 25℃, and the reaction solution gradually changed from yellow and transparent to milky white (e.g., ...). Figure 1 (As shown).

[0038] (3) Adjust the pH of the sodium polythiooctanoate aqueous solution to 4.0 with dilute hydrochloric acid to prepare a white polythiooctanoic acid gel (e.g. Figure 1 (As shown).

[0039] like Figure 2 As shown in the 1H NMR spectrum, although the chemical shifts of most protons in the polymer product are similar to those in the lipoic acid monomer, the proton signal H of the methylene group adjacent to the sulfur atom is significantly different. a and H c Significant changes have occurred. Figure 2 It also shows that H, which belongs to the sodium thiocate monomer, a (δ = 3.14 ppm and 3.18 ppm), H c (δ = 3.66 ppm) shifts significantly to higher fields in the polymer and merges into a broad single peak at 2.89 ppm (H a and H c The small peaks remaining at 3.66 ppm, 3.14 ppm and 3.18 ppm can be attributed to small amounts of residual thioctic acid monomer.

[0040] The obtained polythioctic acid was analyzed by gel permeation chromatography (GPC). GPC analysis was performed on a Waters 1515 isocratic high-performance liquid chromatography system using an Agilent PLgel 5 μm MIXED-C column (manufactured in the UK) at 35 °C; tetrahydrofuran (THF) was used as the mobile phase at a flow rate of 1 mL / min. Polystyrene (PS) was used as a standard for data analysis. Results are as follows: Figure 3 As shown.

[0041] like Figure 3 As shown, gel permeation chromatography analysis revealed that the number-average molecular weight of the obtained polythioctic acid was 71 kg / mol, and the weight-average molecular weight was 216 kg / mol.

[0042] The obtained polythiooctanoic acid was analyzed by matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF-MS). MALDI-TOF-MS analysis was performed on a Bruker Autoflex speed TOF / TOF instrument in positive ion linear mode, with a mass range of 700–3500 Da. trans-2-[3-(4-tert-butylphenyl)-2-propenylidene]malonitrile (DCTB) was used as the matrix. Results are as follows: Figure 4 As shown.

[0043] like Figure 4 As shown, matrix-assisted time-of-flight mass spectrometry (MAFS) reveals a series of single molecular ion peaks with a repeating unit mass of 206.3 Da, corresponding to the molecular weight of sodium thiocate monomer.

[0044] Example 2 The scheme is basically the same as that in Example 1, except that 206.3 mg of thioctic acid is changed to 913.2 mg of thioctic acid to obtain sodium polythiocate and polythioctic acid.

[0045] Example 3 The scheme is basically the same as that in Example 1, except that 206.3 mg of thioctic acid is changed to 11.4 mg of thioctic acid to obtain sodium polythioctic acid and polythioctic acid.

[0046] Example 4 The scheme is basically the same as that in Example 1, except that 19.8 mg of sodium iodate is changed to 39.6 mg of sodium iodate to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0047] Example 5 The scheme is basically the same as that in Example 1, except that 19.8 mg of sodium iodate is changed to 1.98 mg of sodium iodate to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0048] Example 6 The scheme is basically the same as that in Example 1, except that the pH of the NaOH aqueous solution is changed from 7.4 to 8.0 to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0049] Example 7 The scheme is basically the same as that in Example 1, except that the pH of the NaOH aqueous solution is changed from 7.4 to 9.0 to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0050] Example 8 The scheme is basically the same as that in Example 1, except that the reaction temperature is changed from 25°C to 0°C to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0051] Example 9 The scheme is basically the same as that in Example 1, except that the reaction temperature is changed from 25°C to 60°C to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0052] Example 10 The scheme is basically the same as that in Example 1, except that 19.8 mg NaIO3 is replaced with 16.5 mg Na2MnO4 to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0053] Example 11 The scheme is basically the same as that in Example 1, except that 19.8 mg NaIO3 is replaced with 19.7 mg K2MnO4 to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0054] Example 12 The scheme is basically the same as that in Example 1, except that 19.8 mg NaIO3 is changed to 10.7 mg NaClO3 to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0055] Example 13 The scheme is basically the same as that in Example 1, except that 19.8 mg NaIO3 is replaced with 12.3 mg KClO3 to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0056] Example 14 The scheme is basically the same as that in Example 1, except that 19.8 mg NaIO3 is changed to 21.4 mg KIO3 to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0057] Example 15 The scheme is basically the same as that in Example 1, except that 19.8 mg NaIO3 is changed to 38.9 mg Na3[Fe(C2O4)3] to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0058] Example 16 The scheme is basically the same as that in Example 1, except that 19.8 mg NaIO3 is replaced with 49.1 mg K3[Fe(C2O4)3]·3H2O to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0059] Example 17 The scheme is basically the same as that in Example 1, except that 19.8 mg NaIO3 is replaced with 26.8 mg [Co(NH3)6]Cl3 to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0060] Example 18 The scheme is basically the same as that in Example 1, except that 19.8 mg NaIO3 is replaced with 34.4 mg EDTA-Fe. 3+ The complex (prepared by mixing EDTA and FeCl3·6H2O in an equimolar ratio) yields sodium polythiooctanoate and polythiooctanoic acid.

[0061] Gel permeation chromatography (GPC) analysis was performed using the same method as in Example 1, and the results are as follows: Figure 5 As shown.

[0062] Figure 5 The results showed that the number-average molecular weight of the obtained polythiooctanoic acid was 66 kg / mol, and the weight-average molecular weight was 178 kg / mol.

[0063] Example 19 The scheme is basically the same as that in Example 1, except that 19.8 mg NaIO3 is replaced with 45.8 mg EDTA-Co. 3+ The complex (prepared from EDTA and CoCl3 in an equimolar ratio) yields sodium polythiooctanoate and polythiooctanoic acid.

[0064] Example 20 The scheme is essentially the same as in Example 1, except that 19.8 mg of NaIO3 is replaced with Fenton's reagent, which consists of FeSO4·7H2O (1.4 mg) and H2O2 (5.1 μL, 30 wt%). In this system, Fe... 2+ Sodium thiooctanoate reacts with H2O2 in situ via a Fenton reaction to generate hydroxyl radicals (•OH), which in turn initiates the ring-opening polymerization of sodium thiooctanoate to obtain sodium polythiooctanoate and polythiooctanoic acid.

[0065] Gel permeation chromatography (GPC) analysis was performed using the same method as in Example 1, and the results are as follows: Figure 6 As shown.

[0066] Figure 6 The results showed that the number-average molecular weight of the obtained polythiooctanoic acid was 78 kg / mol, and the weight-average molecular weight was 212 kg / mol.

[0067] Example 21 The scheme is essentially the same as in Example 1, except that 19.8 mg of NaIO3 is replaced with Fenton's reagent, which consists of CoSO4·7H2O (1.4 mg) and H2O2 (5.1 μL, 30 wt%). In this system, Co 2+ It reacts with H2O2 in situ to generate hydroxyl radicals (•OH), which in turn initiate the ring-opening polymerization of sodium thiocate.

[0068] Example 22 The scheme is essentially the same as in Example 1, except that 19.8 mg of NaIO3 is replaced with Fenton's reagent, which consists of CuSO4·5H2O (1.3 mg) and H2O2 (5.1 μL, 30 wt%). In this system, Cu 2+ It reacts with H2O2 in situ to generate hydroxyl radicals (•OH), which in turn initiate the ring-opening polymerization of sodium thiocate.

[0069] Example 23 The scheme is basically the same as in Example 1, except that 19.8 mg of NaIO3 is replaced with Fenton's reagent composed of NiCl2·6H2O (1.2 mg) and H2O2 (5.1 μL, 30 wt%). In this system, Ni 2+ It reacts with H2O2 in situ to generate hydroxyl radicals (•OH), which in turn initiate the ring-opening polymerization of sodium thiocate.

[0070] Example 24 The scheme is basically the same as that in Example 1, except that the thioctic acid monomer is dissolved in an aqueous solution of potassium hydroxide and the pH of the solution is controlled at 7.4 to obtain potassium polythiocate and polythioctic acid.

[0071] Example 25 The scheme is basically the same as that in Example 1, except that the thioctic acid monomer is dissolved in an ammonia solution and the pH of the solution is controlled at 7.4 to obtain ammonium polythiocate and polythioctic acid.

[0072] Comparative Example 1 See Zhang et al. (Matter, 2021, 4, 1352) 1364) discloses a method for preparing polythioctic acid elastomers: thioctic acid monomers are subjected to bulk melt thermal ring-opening polymerization to obtain solid polythioctic acid elastomers; the depolymerization behavior and depolymerization kinetics of these polythioctic acid elastomers in alkaline aqueous solutions of different concentrations are investigated. Experimental results show that an alkaline environment readily triggers the dynamic exchange depolymerization of disulfide bonds in the polythioctic acid backbone; within the investigated range, the stronger the alkalinity of the system, the faster the polymer depolymerization rate. This existing technical solution involves first obtaining the polythioctic acid bulk elastomer through bulk thermal polymerization, and then contacting the polymer with an alkaline aqueous solution; if this approach is transferred, an attempt is made to obtain polythioctic acid through bulk polymerization... The method of obtaining an aqueous polymer system by "alkaline dissolution and conversion to obtain polythiooctanoate" has inherent technical defects: the polymer will undergo significant depolymerization when it comes into contact with an alkaline medium, resulting in a low monomer conversion rate and a significantly low molecular weight of the polymer that can be obtained, making it difficult to directly obtain a high molecular weight polythiooctanoate aqueous system.

[0073] Comparative Example 2 See Morris et al. (J. Am. Chem. Soc. 2024, 146, 30662). The fine emulsion polymerization disclosed in 30667 has obvious limitations. The reaction system must rely on surfactants (SDS) and stabilizers (hexadecane) to maintain emulsion stability. After polymerization, the product needs to be separated by methanol precipitation, which increases the use of organic solvents and operation steps. At the same time, the system is limited by the solubility of α-lipoic acid in butyl acrylate (gelation occurs when it exceeds 10 mol%), and the reaction takes a very long time.

[0074] The solutions and products of Examples 1-25 and Comparative Examples 1-2 of the present invention were compared, and the results are shown in Table 1.

[0075] Table 1

[0076] The results show that, compared with existing technologies, the method of this invention has a shorter preparation time, lower reaction temperature, and higher monomer conversion rate. Furthermore, the polythiooctanoic acid prepared by the method of this invention has higher weight-average molecular weight and number-average molecular weight, which can meet the requirements of more fields.

[0077] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing polythiooctanoate in aqueous phase, characterized in that, Includes the following steps: (1) Monomer dissolution: The thioctic acid monomer is dissolved in an alkaline aqueous solution to obtain an alkaline aqueous solution of thiocate salt; (2) Aqueous phase polymerization: A water-soluble initiator is added to an alkaline aqueous solution of thiooctanoate, and the aqueous phase monomer ring-opening polymerization is carried out under normal temperature, normal pressure and open air conditions to obtain a water-soluble polythiooctanoate aqueous solution.

2. The method for preparing polythiooctanoate in aqueous phase according to claim 1, characterized in that, The solute in the alkaline aqueous solution in step (1) is any one of sodium hydroxide, sodium carbonate, sodium bicarbonate, or ammonia.

3. The method for preparing polythiooctanoate in aqueous phase according to claim 2, characterized in that, The pH of the alkaline aqueous solution is 7.4-9.

0.

4. The method for preparing polythiooctanoate in aqueous phase according to claim 1, characterized in that, The molar ratio of thioctic acid salt to initiator in step (2) is 100:1-5:

1.

5. The method for preparing polythiooctanoate in aqueous phase according to claim 4, characterized in that, The concentration of thioctic acid salt in the aqueous solution is 0.005-0.4 mol / L.

6. The method for preparing polythiooctanoate in aqueous phase according to claim 4, characterized in that, The initiator is any one of inorganic salts, organometallic salts, and Fenton-like reagents.

7. The method for preparing polythiooctanoate in aqueous phase according to claim 6, characterized in that, The inorganic salt is any one of sodium manganate, potassium manganate, sodium chlorate, potassium chlorate, sodium iodate, potassium iodate, sodium trioxane ferrate, potassium trioxane ferrate, and hexaminecobalt. The organometallic salt is EDTA and Fe. 3+ or Co 3+ The formed stable complex, and EDTA with Fe 3+ or Co 3+ The molar ratio is 1:1; The Fenton-like reagent is composed of a water-soluble divalent metal salt and hydrogen peroxide, wherein the divalent metal salt is any one of divalent iron salt, divalent copper salt, divalent cobalt salt, and divalent nickel salt.

8. The method for preparing polythiooctanoate in aqueous phase according to claim 1, characterized in that, In step (2), the reaction time for the ring-opening polymerization of the aqueous monomer is 1-30 min, and the reaction stirring rate is 100-1000 rpm.

9. A method for preparing polythiooctanoic acid in an aqueous phase, characterized in that, The water-soluble polythiooctanoic acid aqueous solution prepared by the method according to any one of claims 1-8 comprises the following steps: Add an acidic aqueous solution to the obtained water-soluble polythiooctanoate aqueous solution to adjust the pH of the solution to acidic, and you can obtain polythiooctanoic acid.

10. The method for preparing polythiooctanoic acid in aqueous phase according to claim 9, characterized in that, The solute in the acidic aqueous solution is hydrochloric acid; The pH of the acidic aqueous solution is 3.5-4.5.

Images