A process for accurately controlling the degree of polymerization of thiol diradical polymers

Abstract

The present invention relates to the technical field of polymer degree control, and discloses a precise control process for the degree of polymerization of a thiol diradical polymer. A trimeric disulfide cyclic polymer generates thiol diradicals when exposed to light to form a reversible dynamic combinatorial library (DCL); a two-phase solvent volatilization crystallization method is used to precisely control the degree of polymerization of the thiol diradical polymer (disulfide ring) in the reversible dynamic combinatorial library (DCL). The present invention can form a reversible dynamic combinatorial library (DCL), which provides a basis for the directional transformation of disulfide rings; disulfide rings with different degrees of polymerization in the reversible dynamic combinatorial library have different solubilities, and as the solvent evaporates, tetrameric disulfide rings (QDSM) are preferentially precipitated, which provides power for the directional transformation of disulfide rings, so that the dynamic reversible reaction of DCL proceeds in the direction of QDSM; the present invention can precisely control the degree of polymerization of the thiol diradical polymerization reaction and enable the polymerization system to be self-purified, with a simple process, low energy consumption, easy operation and high conversion rate.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer polymerization degree control, and in particular to a process for accurately controlling the polymerization degree of a thiol diradical polymer. Background Art

[0002] The emergence of the persistent free radical trityl radical in 1900 opened the prelude to the development of free radical chemistry (Gomberg., 1900). In the following 120 years, free radical chemistry has received extensive attention in many fields such as materials, environment, biology, and medicine. Among the many free radical chemical reactions, free radical polymerization has become a hot research topic in free radical chemistry because of its advantages such as a large variety of polymerizable monomer molecules, a wide range of uses for polymerized products, the ability to polymerize in the form of monomers, monomer suspensions, monomer emulsions, monomer solutions, etc., and the ability to polymerize under mild conditions to obtain macromolecular polymers.

[0003] Traditional free radical polymerization has a series of problems such as the difficulty in controlling the molecular weight distribution and segment sequence of the product, the difficulty in separating the monomer and the polymerization product in the system after the polymerization reaction, and the difficulty in synthesizing polymer compounds with the expected molecular structure and terminal functional groups. In the mid-twentieth century, Szwarc proposed the concept of ionic active polymerization, which can better achieve molecular design and structural control compared with traditional free radical polymerization. However, ionic active polymerization reactions are difficult to industrialize due to their harsh conditions, few monomer types, and can only be carried out in non-aqueous media. The high cost of industrialization and other unfavorable factors make it difficult to industrialize. In view of the characteristics of free radical polymerization and ion-active polymerization, controllable active radical polymerization methods with the advantages of easy reaction conditions, simple synthesis operation, and better molecular structure control have been developed: stable "active" free radical polymerization (SFRP), atom transfer radical polymerization (ATRP), and reversible addition-fragmentation chain transfer polymerization (RAFT) have been developed successively. The research on free radical polymerization has developed rapidly, and polymers with different chemical properties, different structures and compositions have also been developed successively. Among them, thiol diradical polymers have become an important research direction for free radical polymerization due to their wide range of applications in daily life and high added value. However, so far, the degree of polymerization of thiol diradical polymers is difficult to accurately control; the difficulty in separating unpolymerized monomers, initiators, and polymerization products of different molecular weights after polymerization in the free radical polymerization system is still a long-standing and difficult problem in the development of thiol diradical polymerization. How to solve this problem is an important content that needs to be studied in the current field of thiol diradical polymerization chemistry.

[0004] The precise control of the degree of polymerization of thiol diradical polymers and the purity of the polymer products are key factors in determining the properties of polymers. Therefore, it is of great significance to develop a process that can precisely control the degree of polymerization of thiol polymers and improve the purity of the polymerization system. Summary of the invention

[0005] In view of this, the present invention provides a process for accurately controlling the polymerization degree of thiol diradical polymers to solve the technical problems in the prior art that the polymerization degree and the spatial topological structure of thiol diradical polymers in free radical polymerization reactions are difficult to accurately control and the products are difficult to purify.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A process for precisely controlling the degree of polymerization of a thiol diradical polymer comprises: utilizing a trimeric disulfide cyclic polymer to generate thiol diradicals under light conditions to form a reversible dynamic combinatorial library (DCL); and adopting a two-phase solvent evaporation crystallization method to precisely control the degree of polymerization of the thiol diradical polymer in the reversible dynamic combinatorial library.

[0008] Preferably, in the above-mentioned process for accurately controlling the degree of polymerization of the thiol diradical polymer, the following steps are included:

[0009] (1) Preparation of TDSM solution: dissolving trimeric disulfide cyclic polymer in an organic solvent to obtain a TDSM solution;

[0010] (2) Preparation of a reversible dynamic combinatorial library: placing the TDSM solution under visible light conditions to break disulfide bonds to generate thiol diradicals, thereby generating a reversible dynamic combinatorial library containing disulfide rings with different degrees of polymerization;

[0011] (3) Directed transformation of disulfide rings: The reversible dynamic combinatorial library is placed under visible light conditions to slowly evaporate the solvent until the solvent is completely evaporated to obtain a tetrameric disulfide ring compound.

[0012] The trimeric disulfide ring compound (TDSM) and the tetrameric disulfide ring compound (QDSM) are shown below;

[0013] The reaction process by which the degree of polymerization of the thiol diradical polymer can be precisely controlled is as follows:

[0014]

[0015] Preferably, in the above-mentioned process for precisely controlling the degree of polymerization of the thiol diradical polymer, step (1) is: firstly completely dissolving the trimeric disulfide cyclic polymer in a good organic solvent, and then continuing to add a bad organic solvent to obtain a TDSM solution.

[0016] Preferably, in the above-mentioned process for precisely controlling the degree of polymerization of the thiol diradical polymer, the volume ratio of the good solvent to the poor solvent in step (1) is (2-4):1;

[0017] Further preferably, the volume ratio of the good solvent to the poor solvent is 3:1.

[0018] Preferably, in the above-mentioned process for precisely controlling the degree of polymerization of the thiol diradical polymer, the benign organic solvent is dichloromethane;

[0019] The poor organic solvent includes any one or more of ethanol, methanol and acetonitrile.

[0020] Preferably, in the above-mentioned process for precisely controlling the degree of polymerization of thiol diradical polymer, the concentration of the TDSM solution is 62.9-78.2 mmol / L.

[0021] Preferably, in the above-mentioned process for precisely controlling the degree of polymerization of thiol diradical polymers, the preparation temperature of the reversible dynamic combinatorial library in step (2) is 20-30°C;

[0022] Further preferably, the preparation temperature of the reversible dynamic combinatorial library is room temperature 25°C.

[0023] Preferably, in the above-mentioned process for precisely controlling the degree of polymerization of the thiol diradical polymer, the time required for the solvent in step (3) to completely evaporate is 16-22 days.

[0024] Preferably, in the above-mentioned process for precise control of the degree of polymerization of thiol diradical polymers, the visible light in step (2) and step (3) is diffusely reflected natural light in the room.

[0025] The present invention provides a process for accurately controlling the degree of polymerization of a thiol diradical polymer. Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The tri-disulfide ring polymer solution prepared by the present invention can form a dynamic reversible combinatorial library (DCL), which provides a basis for the directional transformation of thiol diradicals; disulfide rings with different polymerization degrees in the reversible dynamic combinatorial library have different solubilities. As the solvent evaporates, tetra-disulfide rings (QDSM) with low solubility and large content are preferentially precipitated, thereby causing the dynamic reversible reaction of DCL to proceed in the direction of QDSM, providing a driving force for the directional transformation of thiol diradicals; in the process of precise control of the polymerization degree of thiol diradical polymers, the composition of DCL is only the solvent and disulfide rings with different polymerization degrees, and no other substances are introduced, which provides conditions for the high conversion rate and self-purification behavior of the polymerization process;

[0027] (2) The present invention is a process that can accurately control the degree of polymerization of thiol diradical polymerization reactions and enable the polymerization system to self-purify. The process is simple, has low energy consumption, is easy to operate and has a high conversion rate. The present invention not only provides a new idea and insight for the long-standing and difficult-to-solve problems in free radical polymerization reactions, such as the difficulty in controlling the degree of polymerization and the difficulty in purifying the products, but also provides a new strategy and possibility for the further development of free radical polymerization reactions, and also provides a new method for the purification and separation of complex disulfide supramolecular chemical systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the synthesis route of trimeric disulfide ring TDSM;

[0030] Figure 2 It is 3,5-dihydroxy-butoxybenzene 1 H NMR;

[0031] Figure 3 It is 3,5-bis(dimethylaminothiocarboxylic acid)-butoxybenzene 1 H NMR;

[0032] Figure 4 It is 3,5-bis(dimethylcarbamate thioester)-butoxybenzene 1 H NMR;

[0033] Figure 5 It is 3,5-dimercapto-butoxybenzene 1 H NMR;

[0034] Figure 6 It is a trisulphide ring (TDSM) 1 H NMR;

[0035] Figure 7 is the EPR signal spectrum of thiol diradical;

[0036] Figure 8 It is a process diagram of the precise control process of the polymerization degree of thiol diradical polymer;

[0037] Fig. 9 It is a tetradisulfide ring (QDSM) 1 H NMR;

[0038] Fig.10 It is the precise control process of the polymerization degree of thiol diradical polymer 1 H change graph;

[0039] Fig.11 This is an optical stereo microscope observation diagram of the precise control process of the polymerization degree of thiol diradical polymer;

[0040] Fig.12 It is a liquid chromatogram of the precise control process of the polymerization degree of thiol diradical polymer;

[0041] Fig.13 It is the single crystal diffraction analysis diagram of QDSM;

[0042] Fig.14 It is a system under dark conditions 1 H NMR changes;

[0043] Fig.15 It is a schematic diagram of the ultraviolet absorption of the solution in the ultraviolet absorption test;

[0044] Fig.16 It is the liquid chromatogram of the ring transformation process in the single crystal system under different illumination conditions;

[0045] Fig.17 This is the XPS test result of TDSM solution under different lighting conditions. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The present embodiment provides a process for precisely controlling the degree of polymerization of thiol diradical polymers based on a two-phase solvent evaporation crystallization method, wherein a reversible dynamic combinatorial library is constructed by utilizing the property that trimeric disulfide ring TDSM will generate thiol diradicals when exposed to light in a solution, and the solvent is slowly evaporated to allow tetrameric disulfide rings with low solubility and large content to precipitate preferentially, thereby promoting the polymerization reaction to proceed in the direction of tetrameric disulfide ring QDMS. Finally, all disulfide rings of different degrees of polymerization in the system are converted into tetrameric disulfide ring QDSM, and the thiol diradical polymers are all disulfide ring compounds DSM.

[0048] In some embodiments of the present invention, the process for accurately controlling the degree of polymerization of the thiol diradical polymer comprises the following steps:

[0049] (1) Preparation of TDSM solution: Dissolve the TDSM compound in a good organic solvent, and then slowly add a bad organic solvent to prepare a TDSM solution;

[0050] (2) Preparation of reversible dynamic combinatorial library: The prepared TDSM solution is placed at 20-30°C under visible light conditions, and the property of disulfide bonds to generate thiol diradicals under light is utilized to prepare a reversible dynamic combinatorial library containing disulfide rings with different polymerization degrees;

[0051] (3) Directed transformation of disulfide rings: The reversible dynamic combinatorial library placed under visible light conditions is sealed with a sealing film and allowed to stand, and the solvent is slowly evaporated until all the solvent is evaporated. At this time, only QDSM exists in the system and exists in the form of single crystals.

[0052] In some embodiments of the present invention, the concentration of the raw material trimeric disulfide ring compound is 62.9-78.2 mmol / L.

[0053] In some embodiments of the present invention, the benign organic solvent is dichloromethane, the poor solvent is one or more of ethanol, methanol, and acetonitrile, and the volume ratio of the benign solvent to the poor solvent is 2:1-4:1; further preferably, the benign solvent is dichloromethane, the poor solvent is acetonitrile, and the volume ratio of the benign solvent to the poor solvent is 3:1.

[0054] In some embodiments of the present invention, the visible light is diffusely reflected natural light indoors without direct sunlight.

[0055] In some embodiments of the present invention, the solvent slowly evaporates for 16-22 days.

[0056] In some embodiments of the present invention, the polymer obtained by precisely controlling the degree of polymerization of the thiol diradical is a tetrameric disulfide ring compound (QDSM).

[0057] In a specific embodiment, the application test conditions of the process for accurately controlling the degree of polymerization of thiol diradical polymers are described as follows:

[0058] 1. Synthesis of Trimeric Disulfide Cycle Compound (TDSM)

[0059] The synthetic route of trisulphide ring compound (TDSM) is as follows: Figure 1 This schematic diagram only shows an example of the synthesis method, and the method of the present invention is not limited to the related substances shown in the figure. The specific synthesis steps are as follows:

[0060] (1) Synthesis of Compound 1-2

[0061]

[0062] Phloroglucinol (10 g, 79 mmol) was dissolved in DMF (100 mL), potassium carbonate powder (12 g, 87 mmol) and 1-bromobutane (8 ml, 87 mmol) were added, and stirred at 50 ° C for 24 h. The reaction mixture was cooled and diluted with water, 1N HCl was added dropwise until it was acidic, and then extracted with ethyl acetate. The organic layer was washed with brine, dried over anhydrous sodium sulfate, concentrated, and purified by column (EA / PE=1 / 3) to obtain 4.27 g of 3,5-dihydroxy-butoxybenzene as a reddish brown oil with a yield of 29.7%. 1 H NMR (400MHz, CDCl3, δ:) 5.99 (s, 2H), 5.95 (s, 1H), 3.88 (t, J = 6.6Hz, 2H), 1.76-1.64 (m, 2H), 1.45 (dq, J = 14.7, 7.4Hz, 2H), 0.95ppm (t, J = 7.4Hz, 3H); 13 C NMR(101MHz,CDCl3,δ:)161.37,157.41,95.42,94.87,67.80,31.20,19.22,13.83.MS:m / z:calcd:183.1016;found:183.1016[M+H + ], 1H NMR as attached Figure 2 shown.

[0063] (2) Synthesis of Compounds 1-3

[0064]

[0065] Synthesis steps: 3,5-dihydroxy-butoxybenzene (4.0g, 21.98mmol) was dissolved in 30mL of anhydrous DMF under nitrogen atmosphere and cooled to 0°C. Dabco (12g, 108.3mmol) was added three times and then dimethylaminothioformyl chloride (13.25g, 108.3mmol) was added to the above DMF solution. The reaction was continued for 42h, and the reaction progress was monitored by TLC plate. The mixture after the reaction was poured into 200mL of pure water, extracted with ethyl acetate (40mLx5), concentrated, and column purified (EA / PE=2 / 5) to obtain 4.74g of 3,5-bis(dimethylaminothioformyloxy)-butoxybenzene as a white solid with a yield of 60.6%. 1H NMR(400MHz, CDCl3, δ:)6.52(d,J=2.0Hz,2H),6.44(t,J=2.0Hz,1H),3.93(t,J=6.5Hz,2H),3.4 4(s,6H),3.31(s,6H),1.74(m,J=14.4,6.6Hz,2H),1.52-1.38(m,2H),0.95ppm(t,J=7.4Hz,3H); 13 C NMR(101MHz,CDCl3,δ:)187.24,159.89,154.59,110.12,107.29,68.13,43.28,38.83,31.16,19.20,13.86.MS:m / z:calcd:357.1301;found:357.1301[M+H + ], 1H NMR as attached Figure 3 shown.

[0066] (3) Synthesis of Compounds 1-4

[0067]

[0068] Synthesis steps: 3,5-bis(dimethylaminothiocarbamoyloxy)-butoxybenzene (4.0 g, 11.24 mmol) was suspended in diphenyl ether (48 mL) under a nitrogen atmosphere, and Wood's alloy was used as a heating medium to heat the reaction system to 230-240°C. The reaction was monitored by a TLC plate. After reacting for 3 h, the mixture was cooled to room temperature and purified by a column (EA / PE=3 / 5) to obtain 3,5-bis(dimethylaminothioic acid ester)-butoxybenzene as a brown solid 3.0 g with a yield of 75%. 1 H NMR (400MHz, CDCl3, δ:) 7.21 (s, 1H), 7.07 (d, J = 1.3Hz, 2H), 3.95 (t, J = 6.5Hz, 2 H),3.04(s,12H),1.80-1.66(m,2H),1.54-1.39(m,2H),0.95(t,J=7.4Hz,3H); 13 C NMR (101MHz, CDCl3, δ:)166.52,159.17,134.08,129.82,122.69,67.97,36.94,31.24,19.21,13.86.MS:m / z:calcd:357.1301; found:357.1302[M+H + ], 1H NMR as attached Figure 4 shown.

[0069] (4) Synthesis of Compounds 1-5

[0070]

[0071] Synthesis steps: Add 3,5-bis(dimethylcarbamic acid thioester)-butoxybenzene (2.1547g, 6.04mmol) to 21.6mL diethylene glycol solution (NaOH: 1.75M) under nitrogen atmosphere, react at 105℃ for 1.5h, then cool to room temperature, add 150mL pure water to dilute, and then add 16.3mL 10% hydrochloric acid. After extraction with ethyl acetate, wash the organic phase with aqueous hydrochloric acid solution, and extract again for several times. 1.17g of reddish brown oily 3,5-dimercapto-butoxybenzene is obtained, with a yield of 90.5%. 1 H NMR(400MHz, CDCl3, δ:)6.74(t,J=1.5Hz,1H),6.59(d,J=1.5Hz,2H),3.89(t,J=6.5Hz,2 H),3.42(s,2H),1.78-1.67(m,2H),1.46(dq,J=14.9,7.5Hz,2H),0.96(t,J=7.4Hz,3H); 13 CNMR(101MHz,CDCl3,δ:)159.63,132.80,121.64,112.73,67.87,31.17,19.18,13.80.MS:m / z:calcd:213.0413;found:213.0414[MH + ], 1H NMR as attached Figure 5 shown.

[0072] (5) Synthesis of Compound 1-6 (TDSM)

[0073]

[0074] Synthesis steps: 12.5 mg (0.05 mmol) of iodine and 19 μL (0.25 mmol) of DMSO were dissolved in 63 mL of ethyl acetate, and 53.5 mg (0.25 mmol) of thiol compound was added thereto for reaction, and the reaction was monitored by TLC plate. After 1 h of reaction, part of ethyl acetate was removed by rotary evaporation, and saturated Na2S2O3 (3 x 20.0 mL) solution was added for washing. The organic phase was dried over anhydrous Mg2SO4, filtered, and separated by column purification (eluent: pure petroleum ether) to obtain 28.9 mg of product TDSM, with a yield of 54.5%. 1H NMR(400MHz, CDCl3, δ:)7.23(t,J=1.6Hz,1H),6.91(d,J=1.6Hz,2H),3.94(t,J= 8.5,4.4Hz,2H),1.78-1.68(m,2H),1.53-1.40(m,2H),0.97ppm(t,J=7.4Hz,3H); 13 CNMR(101MHz,CDCl3,δ:)159.73,138.67,119.90,114.48,68.13,31.15,19.19,13.83.MS:m / z:calcd:635.0916;found:635.0913[MH + ], 1H NMR as attached Figure 6 shown.

[0075] 2. Determination of thiol diradicals

[0076] Dissolve TDSM and DMPO in dichloromethane in two sample bottles, respectively, and mix them in a volume ratio of 1:1 to prepare a solution containing 3.0 mg / mL TDSM and 40.0 mmol / L DMPO. Perform EPR testing under diffuse natural light conditions for 2 minutes. The EPR signal of thiol diradicals is shown in the attached figure. Figure 7 As shown, it is shown that light is the cause of the cleavage of disulfide bonds and the generation of thiol diradicals.

[0077] 3. Precise Control of Degree of Polymerization in Thiol Diradical Polymerization

[0078] 40.0mg TDSM sample was placed in a 20.0mL sample bottle, 750.0uL chromatographic grade dichloromethane was slowly added until the sample was completely dissolved, and then 250.0uL chromatographic grade acetonitrile was added, the bottle was sealed with a sealing film, and the bottle was left to stand. A reversible dynamic combinatorial library (DCL) containing thiol diradicals and disulfide rings with different polymerization degrees was generated under diffuse natural light. The polymerization degree of the thiol diradical polymerization reaction was precisely controlled by a two-phase solvent evaporation crystallization method, and the reaction proceeded toward the reaction of tetrameric disulfide rings. All disulfide rings in the system were converted into QDSM and regular octahedral single crystals of QDSM were obtained. The process was characterized by an optical stereo microscope and a liquid chromatograph. The magnification of the optical stereo microscope was 100 times, and the ultraviolet absorption wavelength of the compound of the liquid chromatograph was 256nm.

[0079] Among them, Figure 8 This is a process diagram for the precise control of the degree of polymerization of thiol diradical polymers; Fig. 9 For QDSM 1 H NMR; Fig.10 It is the precise control process of the polymerization degree of thiol diradical polymer1 H NMR change diagram, the right area in the figure is a partial enlargement of the left area. From the figure, it can be seen that there was only TDSM in the dynamic combination library at the beginning. After 2 days, disulfide rings with different polymerization degrees began to form, and the content of TDMS and QDSM dominated. As time went by, the solvent gradually evaporated, and the proportion of disulfide rings with different polymerization degrees began to change. Finally, only QDSM remained, which also showed that light was the cause of the change of disulfide rings; Appendix Fig.11 This is an optical stereomicroscope observation diagram of the precise control process of the polymerization degree of thiol diradical polymer. In the figure, it can be seen that only white TDSM powder appears in the system at the beginning, and then the white TDSM powder decreases as time goes by, and single crystal QDSM and other disulfide ring solids appear, and finally only single crystal QDSM remains; Attached Fig.12 This is a liquid chromatography diagram of the precise control process of the polymerization degree of thiol diradical polymer, which further verifies the Fig.10 The results in Fig.13 This is the single crystal diffraction analysis diagram of QDSM, which further proves that the single crystal is QDSM, and also proves that only QDSM is left in the system without other disulfide ring compounds.

[0080] In addition, the present invention also carried out the following test process:

[0081] 1. Lighting test

[0082] Add 3.0 mg TDSM, 60.0 uL dichloromethane, and 20.0 uL acetonitrile to 5 2.0 mL bottles, seal them with sealing film to make 5 bottles of TDSM solution with the same concentration and composition. Place 5 bottles in the dark, take out one bottle every two days, tear off the sealing film, wait for the solvent to evaporate, and then perform NMR characterization for a total of 8 days. Fig.14 As shown in the figure, the right area is a partial enlargement of the left area. Obviously, the system does not change under dark conditions. Only TDSM exists, and no other disulfide ring exists, which further proves that light is the cause of the ring transformation. This result is consistent with the attached Figure 7 , Attachment Fig.10 , Attachment Fig.12 The results corroborated each other, proving that light was the cause of the changes in the disulfide ring.

[0083] 2. UV test

[0084] Weigh 1.0 mg of TDSM and QDSM respectively, then add 20.0 mL of dichloromethane to each to make a solution with a concentration of 0.05 mg / mL, and then measure the UV absorption of TDSM and QDSM solutions respectively, see Fig.15 From the data in the figure, we can see that the UV absorption of TDSM and QDSM at 256nm is not much different. Fig.12 It can be concluded from the data in the liquid chromatogram that when the system transformation reaches dynamic equilibrium, the components in the system are mainly TDSM and QDSM, and the contents of TDSM and QDSM are the largest, occupying a dominant position.

[0085] 3. Disulfide ring transformation experiment under indoor diffuse natural light and continuous irradiation of 400nm wavelength light:

[0086] ① Diffuse natural light: Weigh 3.0 mg of TDSM into a headspace injection bottle, add 60.0 uL of dichloromethane (chromatographic grade) and 20.0 uL of acetonitrile (chromatographic grade), and seal it with a bottle cap and sealing film. Place it under diffuse natural light indoors. Use a microinjector to extract 10.0 uL every two hours, dilute it 100 times, and record it with liquid chromatography for a total of 6 hours;

[0087] ②400nm wavelength light: Weigh 3.0mg TDSM into a headspace injection bottle, add 60.0uL dichloromethane (chromatographic grade) and 20.0uL acetonitrile (chromatographic grade), and seal it with a bottle cap and sealing film, place it under a 400nm LED lamp (the lamp head is 0.5cm from the bottom of the injection bottle, and the light power is 0.685w). Every two hours, use a micro-injector to extract 10.0uL and dilute it to 100 times, then record it with liquid chromatography, for a total of 6 hours. The results are as attached Fig.16 As shown, the results indicate that under natural indoor diffuse light conditions, only conversion between disulfide rings will occur, while under continuous irradiation with light of 400nm wavelength, the changes that occur in the system are not conversion between disulfide rings.

[0088] ③ In order to further clarify the changes of disulfide ring compounds under 400nm light, we conducted XPS tests on TDSM solutions under natural light diffuse reflection conditions for 6h and 400nm light for 6h. The results are shown in the attached figure. Fig.17 As shown, the results show that under diffuse light conditions, there is only a disulfide ring in the system, while under 400nm continuous light conditions, the disulfide bonds in the disulfide ring are oxidized to generate sulfone compounds.

[0089] In summary, the transformation of the disulfide ring will not occur in the system under dark conditions. The ring transformation can only occur under natural diffuse reflection visible light conditions, thereby enabling precise control of the polymerization of thiol diradicals.

[0090] The process for precisely controlling the polymerization degree of the thiol diradical polymer of the present invention exhibits excellent precise control of the polymerization degree of the polymer and the spatial topological structure of the polymer, a conversion rate close to 100%, and excellent self-purification performance of the polymerization system.

[0091] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the scheme disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0092] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for accurately controlling the degree of polymerization of a thiol diradical polymer, characterized in that: The following steps are involved: (1) Preparation of TDSM solution: dissolving trimeric disulfide cyclic polymer in an organic solvent to obtain a TDSM solution; (2) Preparation of a reversible dynamic combinatorial library: placing the TDSM solution under visible light conditions to break disulfide bonds to generate thiol diradicals, thereby generating a reversible dynamic combinatorial library containing disulfide rings with different degrees of polymerization; (3) Directed transformation of disulfide rings: placing the reversible dynamic combinatorial library under visible light conditions to slowly evaporate the solvent until the solvent is completely evaporated to obtain a tetrameric disulfide ring compound; Wherein, step (1) is: Firstly, the tris-disulfide cyclic polymer is completely dissolved in a good organic solvent, and then a bad organic solvent is added to obtain a TDSM solution; The volume ratio of the good organic solvent to the bad organic solvent in step (1) is (2-4):1; The benign organic solvent is dichloromethane; The poor organic solvent includes any one or more of ethanol, methanol, and acetonitrile; wherein the structural formula of the trimeric disulfide ring compound is:

2. The process for accurately controlling the degree of polymerization of thiol diradical polymer according to claim 1, characterized in that: The concentration of the TDSM solution is 62.9-78.2 mmol / L.

3. The process for accurately controlling the degree of polymerization of thiol diradical polymer according to claim 1, characterized in that: The preparation temperature of the reversible dynamic combinatorial library in step (2) is 20-30°C.

4. The process for accurately controlling the degree of polymerization of thiol diradical polymer according to claim 1, characterized in that: The time required for the solvent in step (3) to completely evaporate is 16-22 days.

5. The process for accurately controlling the degree of polymerization of thiol diradical polymer according to claim 1, characterized in that: The visible light in step (2) and step (3) is diffusely reflected natural light in the room.

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