Main / side chain degradable acrylate polymers containing thioester and dynamic boronic ester structures and methods of making the same

Abstract

The application discloses a main / side chain degradable acrylate polymer containing a thioester and a dynamic borate ester structure and a preparation method thereof. The preparation method comprises the following steps: firstly, a thioester monomer containing a fragile bond is synthesized; then, a vinyl monomer containing an epoxy functional group and a polymerization inhibitor are added into a sulfuric acid aqueous solution and stirred to react; after neutralization, sodium chloride is added, the mixture is extracted, and after reduced pressure distillation, the product is dissolved in an organic solvent, a borate monomer and anhydrous magnesium sulfate are added, and after reaction, the product is purified; finally, the thioester monomer, the vinyl crosslinking monomer containing the dynamic borate ester structure and the acrylate monomer are polymerized to obtain the target product. The main / side chain degradable acrylate polymer in the application is sensitive to ammonia, alkali and oxidation conditions through the thioester unit and the dynamic borate ester structure, and the degradation of the polymer can be realized under mild conditions; meanwhile, the dynamic crosslinking can also enable the polymer to have excellent mechanical properties.

Description

Technical Field

[0001] This invention relates to biodegradable acrylates, particularly main / side chain biodegradable acrylate polymers with sulfur-containing esters and dynamic borate ester structures, and methods for their preparation. Background Technology

[0002] Traditional acrylate polymers possess excellent mechanical properties and chemical stability, but due to the stability of their structure, they are difficult to degrade in the environment, leading to serious plastic pollution problems. Therefore, the development of biodegradable acrylate polymers has become a research hotspot.

[0003] Main-chain degradable acrylate polymers are a class of polymers that can be degraded into smaller molecules under specific conditions by introducing degradable chemical structures or functional groups into the main chain, thus addressing environmental pollution problems.

[0004] Chinese invention patent application CN117304846A discloses a partially degradable water-based acrylic pressure-sensitive adhesive and an environmentally friendly, recyclable sealing tape. The raw material components of this acrylic pressure-sensitive adhesive include acrylic acid, methacrylic acid, acrylamide, 2-hydroxyethyl acrylate, butyl acrylate, emulsifier, initiator, deionized water, sodium hydroxide, n-dodecyl mercaptan, and water-based rosin resin. The sealing tape is obtained by coating a partially degradable water-based acrylic pressure-sensitive adhesive (which dissolves in water after drying) onto a fully degradable hydrophilic transparent ionomer cellulose membrane. This acrylic pressure-sensitive adhesive dissolves upon contact with water after drying. However, the characteristics of this invention limit the application of the tape, making it unsuitable for many scenarios such as outdoor operations and cargo transportation.

[0005] Chinese invention patent CN106317346B discloses a method for preparing a biodegradable antifouling resin and its applications, comprising: synthesizing a biodegradable polylactic acid block polymer P1 using lactic acid, polyols, and / or polyester polyols as raw materials; then synthesizing a polylactic acid block polymer P2 using P1, triethylamine, methacryloyl chloride, etc. as raw materials; and finally synthesizing a biodegradable acrylate polymer P3 using P2, methacrylate monomers, etc. as raw materials. The biodegradable antifouling resin P3 prepared by this technology can be applied to biodegradable antifouling coatings, and the prepared antifouling coatings exhibit excellent resistance to seawater immersion and controllable degradation. However, its tensile strength is affected by the lactic acid monomer units: the lactic acid moiety causes the polymer to have relatively low tensile strength and low elongation, and the lactic acid groups are prone to brittle fracture, exhibiting relative brittleness and low fracture toughness. Therefore, the mechanical properties of this biodegradable resin need to be improved.

[0006] Chinese invention patent CN115477741B discloses a biodegradable polymer, its preparation method, and its applications. This technology uses ε-caprolactone monomer and hydroxyphenylboronic acid as raw materials for bulk polymerization, employing hydroxyphenylboronic acid as both an initiator and catalyst to directly obtain a biodegradable polymer with α-terminus phenylboronic acid and ω-terminus hydroxyl groups. While this technology improves the water solubility of the biodegradable polymer composed of a polyester backbone by connecting hydroxyphenylboronic acid and hydroxyl structures to both ends of the polyester backbone, the main chain biodegradable polymer exhibits low fracture toughness and mechanical strength, and it is difficult to achieve a high modulus; therefore, the mechanical properties of this biodegradable resin remain insufficient. Summary of the Invention

[0007] The purpose of this invention is to provide a main / side chain biodegradable acrylate polymer with sulfur-containing ester and dynamic borate ester structures that can achieve both excellent mechanical and degradation properties, as well as a method for its preparation, thereby reducing resource waste and environmental pollution.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] Degradable acrylate polymers containing sulfur esters and dynamic borate ester structures, with main / side chain structures, have the following structural formulas:

[0010]

[0011] Where m1, m2, m3, m4 = 30 - 36, n1, n2, n3, n4 = 24 - 29;

[0012] R1 is one of the following groups:

[0013]

[0014] R2 is one of the following groups:

[0015]

[0016] R3 is one of the following groups:

[0017]

[0018] The method for preparing the main / side chain degradable acrylate polymer containing sulfur esters and dynamic borate esters includes the following steps:

[0019] 1) Dissolve the lactone monomer in an aqueous organic solvent, add a sulfiding agent, stir and react for 5-8 hours under an inert atmosphere, remove the organic solvent, and separate by chromatography to obtain the sulfide monomer.

[0020] 2) Add the vinyl monomer containing epoxy functional groups and the polymerization inhibitor to an aqueous sulfuric acid solution. Stir the resulting mixture at 70-80℃ for 2-4 hours and cool to room temperature. After neutralization, add sodium chloride, extract the mixture, and distill under reduced pressure to obtain a vinyl monomer containing an ortho-diol structure. Dissolve the obtained product in an organic solvent, add boric acid monomers and anhydrous magnesium sulfate, stir the reaction at room temperature for 12-24 hours, then raise the temperature to 40-60℃ and distill under reduced pressure to remove the organic solvent mentioned in this step. After purification, obtain a vinyl crosslinking monomer containing a dynamic borate ester structure.

[0021] 3) After mixing deionized water, initiator and emulsifier, replace the air under an inert atmosphere; add thioester monomer, vinyl crosslinking monomer with dynamic borate ester structure and acrylate monomer, mix and ultrasonically disperse, stir and react at 70-80℃ to obtain a biodegradable acrylate polymer with main / side chain containing thioester and dynamic borate ester structure.

[0022] To further achieve the objective of this invention, preferably, in step 1), the lactone monomer is one or more of 4-ethyl-6-methyltetrahydro-2H-pyran-2-one, 4,4,5-trimethyldihydrofuran-2(3H)-one, 3,3,5-trimethyldihydrofuran-2(3H)-one, and dibenzo[c,e]oxetane-5(7H)-one; the vulcanizing agent is one or more of Lawesson reagent, phosphorus pentasulfide, and carbon disulfide; and the molar ratio of the lactone monomer to the vulcanizing agent is 1:0.5-1:2.

[0023] Preferably, in step 1), the organic solvent is one or more of tetrahydrofuran, benzene, and toluene, and the amount of organic solvent used per gram of lactone monomer is 10-50 mL; the reflux temperature is 5-10°C higher than the boiling point of the organic solvent used, and the organic solvent is removed by rotary evaporation under negative pressure at 40-60°C; the inert atmosphere is one of nitrogen or argon.

[0024] Preferably, in step 1), the chromatographic separation is performed by obtaining the optimal sample R to be separated using thin-layer chromatography. f The value is 0.2-0.4, and the separation is performed by column chromatography, wherein the volume ratio of the weakly polar solvent and the strongly polar solvent in the mobile phase is 1:1-4:1; the weakly polar solvent is one or more of pentane, petroleum ether and n-hexane; the strongly polar solvent is one or more of dichloromethane, ethyl acetate and methanol.

[0025] Preferably, in step 2), the vinyl monomer containing the epoxy functional group is one or more of 1-(ethylene oxide-2-yl)propane-2-yl acrylate, 1-(ethylene oxide-2-yl)propyl acrylate, 4-(ethylene oxide-2-yl)butane-2-ylpropionate, and ethylene oxide-2-yl methacrylate; the boric acid monomer is one or more of (3-vinylbenzyl)boric acid, (3-methyl-5-vinylphenylethyl)boric acid, (2-(4-vinylphenyl)propyl)boric acid, and (4-vinylphenyl)boric acid; and the molar ratio of the boric acid monomer to the vinyl monomer containing the epoxy functional group is 1:1 to 1:2.

[0026] Preferably, in step 2), the polymerization inhibitor is one or more of p-methoxyanisole, hydroquinone, 2,6-di-tert-butyl-p-cresol, and 2-tert-butyl-p-hydroxyquinone; the mass ratio of the polymerization inhibitor to the boric acid monomer is 0.1:100-0.2:100; and the extractant is one or more of ethyl acetate, dichloromethane, and diethyl ether.

[0027] Preferably, in step 2), the mass ratio of sulfuric acid to water in the sulfuric acid aqueous solution is 1:100-1.5:100; the addition of anhydrous magnesium sulfate is to remove water from the reaction and promote the forward reaction; the neutralization is carried out by adding an alkaline compound to control the pH to 7-7.5; the alkaline compound is one or more of Na2CO3, K2CO3, and NaHCO3; the addition of sodium chloride is to promote salting out; the mass ratio of sodium chloride to boric acid monomer is 1:10-1:5.

[0028] Preferably, in step 2), the molar ratio of anhydrous magnesium sulfate to boric acid monomer is 2:1-5:1; the organic solvent is one or more of ethyl acetate, dichloromethane, and diethyl ether, with 10-50 mL of organic solvent added per gram of boric acid monomer; the purification involves washing with a low-boiling-point solvent to remove unreacted raw materials; the mass ratio of boric acid monomer to low-boiling-point solvent is 1:9-1:2, and the low-boiling-point solvent is one or more of diethyl ether, petroleum ether, n-pentane, isopentane, and n-hexane; the low-boiling-point solvent is removed after standing under negative pressure at 20-40°C for 8-24 hours.

[0029] Preferably, in step 3), the acrylate monomer is one or more of methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, tert-butyl acrylate, and butyl methacrylate; the mass ratio of the thioester monomer to the acrylate monomer is 1:9-3:7; and the mass ratio of the vinyl crosslinking monomer containing the dynamic borate ester structure and the thioester monomer to the acrylate monomer is 1:100-5:100.

[0030] Preferably, in step 3), the initiator is one or more of potassium persulfate, sodium persulfate, and ammonium persulfate; the emulsifier is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium dodecyl diphenyl ether disulfonate; the amount of initiator is 1%-2% of the total monomer mass, and the amount of emulsifier is 1%-2% of the total monomer mass; the total monomer mass is the sum of the masses of lactone monomer, crosslinking monomer containing dynamic borate ester structure, and acrylate monomer; the ultrasonic dispersion time is 10-20 min; the stirring speed is 200-300 rpm; the inert atmosphere is one of nitrogen or argon, and the inert atmosphere replacement time is 20-40 min.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0032] 1. The dynamic borate ester structure and thioester bond in the main / side chain degradable acrylate polymer prepared in this invention can simultaneously endow the material with excellent mechanical properties and degradability;

[0033] 2. The main / side chain degradable acrylate polymers prepared in this invention can be degraded under conditions such as ammonolysis, alkaline hydrolysis and oxidative degradation. The degradation conditions are mild, and the whole process has low energy consumption and low pollution.

[0034] 3. The preparation method of the main / side chain degradable acrylate polymer in this invention is simple, the synthesis conditions are mild, the solvent used in the preparation process can be reused, and the prepared polymer can be used in high value-added industries. Attached Figure Description

[0035] Figure 1 The 1H-NMR spectrum of the degradable monomer SDT containing sulfur ester bonds;

[0036] Figure 2 The 1H-NMR NMR spectrum of DVTB, a crosslinked monomer containing a dynamic borate ester structure;

[0037] Figure 3 The ATR infrared spectra of the PA / SDT-DVTB polymer in Example 1 and the comparative PA / SDT-TGDE polymer are shown below.

[0038] Figure 4 GPC diagram of the degradation products of PA / SDT-DVTB in Example 1;

[0039] Figure 5 The graph shows the mechanical properties of the PA / SDT-DVTB polymer in Example 1 and the PA / SDT-TGDE polymer in the comparative example. Detailed Implementation

[0040] To better understand the present invention, specific embodiments are described below. However, these embodiments do not constitute a limitation on the scope of protection of the claims of the present invention. Other embodiments obtained by those skilled in the art based on these embodiments without creative effort are all within the scope of protection of the present invention.

[0041] The recycling of high-precision instruments such as optoelectronic devices in high-value-added industries is a major challenge. The acrylate polymer prepared in this invention is both biodegradable and possesses good mechanical properties, making it a viable alternative to existing polymer products in high-precision instruments. It achieves efficient and environmentally friendly polymer degradation and instrument recycling through a simple degradation method, replacing conventional solvent recycling methods. The biodegradable acrylate polymer prepared in this invention can be applied to the coating of optoelectronic devices such as printed circuit boards (PCBs): as a protective coating material for the circuit board, requiring high precision and good mechanical strength to prevent damage; and after the instrument's lifespan, it facilitates the recycling of the circuit board and other internal components, achieving the reuse of high-value-added products.

[0042] This invention proposes a biodegradable acrylate polymer with a main chain containing a sulfur ester structure and a dynamic borate ester structure on the side chain, based on the design of polymer molecular structures. This improves the mechanical properties of the biodegradable acrylate polymer, extends the service life of the material, and solves the problem of environmental pollution.

[0043] The thioester monomer used in this invention is incorporated into the polymer backbone via free radical ring-opening polymerization. Its structure contains fragile bonds, allowing for ammonolysis, alkaline hydrolysis, and oxidative degradation under specific conditions. Boric acid monomers and vinyl monomers containing vicinal diol structures are then used as raw materials to prepare crosslinked monomers with dynamic borate ester structures through dehydration condensation. The resulting biodegradable acrylate polymer is prepared from these crosslinked monomers. The dynamic borate ester structure and the fragile bonds of the thioester exhibit similar degradation characteristics, and under normal use, the crosslinked polymer does not exhibit small molecule efflux that weakens the material's mechanical properties, thus improving safety, reliability, and extending service life.

[0044] Biodegradable acrylate polymers, by introducing biodegradable and fragile thioester bonds into the main chain, can be broken under specific conditions. This not only makes them environmentally friendly, but also allows them to degrade into harmless substances after use, reducing environmental pollution. Dynamic covalent bonds are a type of covalent bond that can reversibly form and break under external stimuli. Boronate bonds, as a typical dynamic covalent bond, have the following characteristics:

[0045] Reversibility: Under specific conditions, the borate ester bond can break and reform. The dynamic borate ester structure is prone to hydrolysis in the presence of water, generating boric acid and diol.

[0046] It is sensitive to environmental stimuli (pH value): under alkaline conditions, the borate ester bond is also easily broken to form borate and the corresponding alcohol.

[0047] Introducing the covalent structure of dynamic borate esters into polymer networks can endow materials with many excellent properties: under appropriate conditions, the borate ester bonds can break, allowing the material to degrade into harmless small molecules; the rigid structure of dynamic borate esters can also give the material excellent mechanical properties. Therefore, degradable acrylate polymers with main / side chain structures containing sulfur esters and dynamic borate esters are of great significance in solving the problem of plastic pollution and promoting the development of sustainable materials.

[0048] The dynamically cross-linked biodegradable polymer of this invention exhibits higher tensile strength because the cross-linked structure more effectively disperses stress. It also typically possesses higher modulus and fracture toughness due to the network structure provided by the cross-linking points, attributed to the effective resistance to crack propagation by the dynamically cross-linked structure. This polymer possesses excellent mechanical properties and can degrade and repair mechanical damage under appropriate conditions, reducing resource waste and environmental pollution.

[0049] In this invention, a degradable acrylate polymer with a main / side chain containing a thioester and a dynamic borate ester structure is prepared by first synthesizing a thioester monomer containing a fragile bond, which is then incorporated into the main chain of the acrylate polymer via free radical ring-opening polymerization to achieve degradability. Next, using borate monomers and vinyl monomers containing vicinal diol structures as raw materials, a crosslinking monomer with a dynamic borate ester structure is prepared through dehydration condensation to achieve dynamic crosslinking of the polymer. Finally, the thioester monomer, the crosslinking monomer with the dynamic borate ester structure, and the acrylate monomer are polymerized to obtain a degradable acrylate polymer with a main / side chain containing a thioester and a dynamic borate ester structure.

[0050] The present invention discloses a method for preparing a main / side chain biodegradable acrylate polymer containing a sulfur ester and a dynamic borate ester structure, which specifically includes the following steps:

[0051] 1) Dissolve the lactone monomer in an aqueous organic solvent, add a sulfiding agent, stir and react for 5-8 hours under an inert atmosphere, remove the organic solvent, and separate by chromatography to obtain the sulfide monomer.

[0052] 2) Add the vinyl monomer containing epoxy functional groups and the polymerization inhibitor to an aqueous sulfuric acid solution. Stir the resulting mixture at 70-80℃ for 2-4 hours and cool to room temperature. After neutralization, add sodium chloride, extract the mixture, and distill under reduced pressure to obtain a vinyl monomer containing an ortho-diol structure. Dissolve the obtained product in an organic solvent, add boric acid monomers and anhydrous magnesium sulfate, stir the reaction at room temperature for 12-24 hours, then raise the temperature to 40-60℃ and distill under reduced pressure to remove the organic solvent mentioned in this step. After purification, obtain a vinyl crosslinking monomer containing a dynamic borate ester structure.

[0053] 3) After mixing deionized water, initiator and emulsifier, replace the air under an inert atmosphere; add thioester monomer, vinyl crosslinking monomer with dynamic borate ester structure and acrylate monomer, mix and ultrasonically disperse, stir and react at 70-80℃ to obtain a biodegradable acrylate polymer with main / side chain containing thioester and dynamic borate ester structure.

[0054] The present invention relates to a main / side-chain biodegradable acrylate polymer containing a thioester and a dynamic borate ester structure, having the following structural formula:

[0055]

[0056] Where m1, m2, m3, m4 = 30 - 36, n1, n2, n3, n4 = 24 - 29;

[0057] R1 is one of the following groups:

[0058]

[0059] R2 is one of the following groups:

[0060]

[0061] R3 is one of the following groups:

[0062]

[0063] Based on the main / side chain biodegradable acrylate polymer structure of the present invention containing sulfur esters and dynamic borate esters, the lactone monomers, vinyl monomers containing epoxy functional groups, borate monomers, sulfur ester monomers, and acrylate monomers involved in its preparation method can all be selected according to the purpose of the invention; as for the auxiliary raw materials such as organic solvents, vulcanizing agents, initiators, and emulsifiers, they can all be selected according to the dissolution requirements, vulcanization requirements, and the initiation and emulsification requirements of this type of reaction.

[0064] The testing methods in this embodiment of the invention are as follows:

[0065] Nuclear magnetic resonance (NMR): ¹H spectra were recorded at 25 °C using a Bruker Avance III 400 MHz spectrometer (¹H: 400 MHz). The sample was in CDCl₃ at approximately 30 mg / mL. -1 The concentration was diluted. NMR spectra were recorded using a 5 mm BBFO+ probe with a z-gradient coil.

[0066] Fourier Transform Infrared (FTIR) spectroscopy: For bulk polymer film samples, an Attenuated Total Reflectance (ATR) attachment is used to directly test the elastic film after deposition. The FTIR spectroscopy test range is 4000 cm⁻¹. -1 Up to 400cm -1 The resolution is 4cm. -1 The number of scans was 32.

[0067] GPC testing: SEC analysis was performed using a Viscotek (Malvern Instruments) system comprising a four-capillary differential viscometer, a differential refractive index (RI) detector, and a UV detector. THF was used as the mobile phase at a flow rate of 1 mL / min. -1 35℃. After filtration through a 0.45μm PTFE membrane, the solution was administered at 3 to 5 mg / mL. -1 All samples were injected at a concentration of [specific concentration]. Separation was performed on three polymer standard service columns (SDVB, 5 μm, 300 × 7.5 mm) and one guard column. Mean molar mass (number-average molar mass, Mn and weight-average molar mass, Mw) and molar mass dispersion were measured.

[0068] Mechanical property testing: The mechanical properties of the samples were characterized using a universal testing machine. Thin films with a thickness of 0.9-1.2 mm were cut into type 4 dumbbell-shaped strips according to national standard GB / T 528-2009, with dimensions of 2×35 mm, a gauge length of 12 mm, and a tensile rate of 500 mm / min. -1 The test temperature was 23±2℃ and the humidity was 60±10%. Each sample was tested at least 3 times and the average value was taken.

[0069] Example 1

[0070] A method for preparing a main / side chain degradable acrylate polymer PA / SDT-DVTB containing sulfur ester and dynamic borate ester structure, comprising the following steps:

[0071] Synthesis and purification of thioester monomers: 10.54 g of dibenzo[c,e]oxetane-5(7H)-one was dissolved in 60 mL of toluene, followed by the slow addition of 32.32 g of Lawesson's reagent. The mixture was stirred under a nitrogen atmosphere, heated to 115 °C, and refluxed for 7 h. Toluene was then removed by rotary evaporation to obtain a viscous liquid. The optimal sample R to be separated was obtained by thin-layer chromatography. fThe value was 0.4. At this point, the mobile phase ratio was n-hexane (weakly polar solvent): dichloromethane (strongly polar solvent) = 2:1. The viscous liquid was separated by column chromatography using silica gel powder as the adsorbent. The mobile phase solvent was then removed by vacuum distillation to obtain the degradable monomer dibenzo[c,e]oxetine-5(7H)-thione (SDT) containing a sulfur ester bond, with a yield of 35% (yield = 100% × actual yield of target product / theoretical yield of target product). The 1H-NMR spectrum of SDT was obtained by Bruker Avance III 400MHz spectrometer. The 1H-NMR spectrum of the DOT monomer is shown below. Figure 1 The successful synthesis of SDT was confirmed. The ¹H NMR (500 MHz, Chloroform-d) values ​​were δ 8.18 (d, J = 8.9 Hz, 1H), 7.67 (d, J = 7.7 Hz, 2H), 7.62 (t, J = 6.9 Hz, 1H), 7.58–7.51 (m, 2H), 7.47 (d, J = 4.9 Hz, 2H), and 5.20 (d, J = 24.1 Hz, 2H).

[0072] Synthesis and purification of borate ester monomers: 60g of ethylene oxide-2-yl methacrylate and 0.06g of p-methoxyanisole were added to 180g of aqueous solution containing 2g of sulfuric acid. The mixture was stirred at 80℃ for 2h and then cooled to room temperature. First, 4g of Na2CO3 was added to neutralize excess acid in the reaction. Then, 5g of sodium chloride was added to promote salting out, accelerate the separation of the aqueous and organic phases, inhibit the formation of the emulsion layer, and improve the extraction rate. The mixture was then extracted with 250mL of ethyl acetate. The extraction was repeated three times. 5g of anhydrous magnesium sulfate was then added to remove water from the ethyl acetate. After removing the ethyl acetate by vacuum distillation, the vinyl monomer 2,3-dihydroxypropyl methacrylate containing the vicinal diol structure was obtained. 18 g of (4-vinylphenyl)boronic acid was added dropwise to 200 mL of tetrahydrofuran, followed by the slow addition of 12.6 g of 2,3-dihydroxypropyl methacrylate and 14 g of anhydrous magnesium sulfate. The mixture was stirred at room temperature for 12 h, then filtered to remove the magnesium sulfate. The mixture was then heated to 55 °C and distilled under reduced pressure to remove the tetrahydrofuran, yielding a viscous liquid. This liquid was washed with diethyl ether to remove unreacted reactants, resulting in a colorless, viscous liquid, which was the vinyl crosslinking monomer (2-(4-vinylphenyl)-1,3,2-dioxaborane-4-yl)methacrylate (DVTB) containing a dynamic borate ester structure. The yield was 88% (yield = 100% × actual yield of target product / theoretical yield of target product). The 1H-NMR spectrum of DVTB was obtained using a Bruker Avance III 400 MHz spectrometer, as shown below. Figure 2The successful synthesis of DVTB was confirmed. The ¹H NMR (600 MHz, Chloroform-d) values ​​were: δ 7.84–7.73 (m, 2H), 7.48–7.38 (m, 2H), 6.73 (dd, J = 17.6, 10.9 Hz, 1H), 6.16–6.05 (m, 1H), 5.88–5.77 (m, 1H), 5.61–5.51 (m, 1H), 5.37–5.25 (m, 1H), 4.84 (ddt, J = 8.3, 6.1, 4.2 Hz, 1H), 4.52–4.14 (m, 4H), and 1.94–1.88 (m, 3H).

[0073] Preparation of degradable acrylate polymers with main / side chains containing sulfur esters and dynamic borate ester structures: 40 g of deionized water, 0.15 g of potassium persulfate (KPS, 1.5 wt.% vs. monomers, the total mass of monomers being the sum of SDT monomers, DVTB monomers, and acrylate monomers) and 0.2 g of sodium dodecyl sulfate (SDS, 2.0 wt.% vs. monomers, the total mass of monomers being the sum of SDT monomers, DVTB monomers, and acrylate monomers) were added to a 50 mL flask. The mixture was purged with nitrogen for 20 min. Then, 0.9 g of SDT, 0.3 g of DVTB, and 8.8 g of acrylate monomers (4.4 g of methyl methacrylate and 4.4 g of butyl acrylate) were added. The mixture was stirred at 250 rpm for 4 h at 70 °C to obtain the degradable acrylate polymer PA / SDT-DVTB (20 wt.%) with main / side chains containing sulfur esters and dynamic borate ester structures. The Fourier transform infrared (FTIR) spectra of the PA / SDT-DVTB polymer in Example 1 and the comparative PA / SDT-TGDE polymer were tested, and the FTIR spectra are shown below. Figure 3 As shown: 1686cm -1 The stretching vibration peak at 1606 cm⁻¹, representing -SC=O, confirms the incorporation of the SDT monomer into the polymer backbone; -1 The peak at the position representing the stretching vibration of the borate ester bond proves that the DVTB monomer is incorporated into the polymer side chain, thus confirming the successful preparation of the PA / SDT-DVTB polymer.

[0074] The following examples, which demonstrate similar aspects of borate monomers, borate monomers, and main / side chain degradable acrylate polymers with sulfur-containing esters and dynamic borate structures, are not provided individually.

[0075] Example 2

[0076] A method for preparing a main / side chain biodegradable acrylate polymer PA / TDT-EDMP containing sulfur ester and dynamic borate ester structure includes the following steps:

[0077] Synthesis and purification of thioester monomers: 11.54 g of 4,4,5-trimethyldihydrofuran-2(3H)-one was dissolved in 80 mL of benzene, followed by the slow addition of 22.21 g of phosphorus pentasulfide reagent. The mixture was stirred under an argon atmosphere and heated to 85 °C under reflux for 6 h. After the reaction, most of the organic solvent was removed by rotary evaporation. The remaining viscous liquid was separated by column chromatography, and the optimal sample R was obtained by thin-layer chromatography. f The value was 0.3, at which point the mobile phase ratio was n-hexane (weakly polar solvent): ethyl acetate (strongly polar solvent) = 3:1. The above products were separated by column chromatography using alumina as the adsorbent, yielding a clear solution. The clear solution was then heated to 60℃ and subjected to vacuum distillation to remove the mobile phase solvent, yielding the degradable monomer 4,4,5-trimethyldihydrofuran-2(3H)-thione (TDT) containing a sulfur ester bond, with a yield of 57% (yield = 100% × actual yield of target product / theoretical yield of target product).

[0078] Synthesis and purification of borate ester monomers: 40 g of 1-(ethylene oxide-2-yl)propyl acrylate and 0.04 g of 2,6-di-tert-butyl-p-toluene were added to 150 g of aqueous solution containing 1.5 g of sulfuric acid. The mixture was stirred at 70 °C for 4 h and then cooled to room temperature. First, 5 g of K₂CO₃ was added to neutralize excess acid in the reaction. Then, 7 g of sodium chloride was added to promote salting out, accelerate the separation of the aqueous and organic phases, inhibit the formation of the emulsion layer, and improve the extraction rate. The mixture was extracted with 280 mL of ethyl acetate, and the extraction was repeated three times. Then, 5 g of anhydrous magnesium sulfate was added to remove water from the ethyl acetate. After removing the ethyl acetate by vacuum distillation, the resulting product was 1,2-dihydroxypentane-3-yl acrylate, a colorless viscous liquid containing a vicinal diol structure. 16 g of (3-methyl-5-vinylphenylethyl)boronic acid was dissolved in 300 mL of tetrahydrofuran. 13.4 g of 1,2-dihydroxypentane-3-yl acrylate was slowly added dropwise, followed by 12 g of anhydrous magnesium sulfate. The mixture was stirred at room temperature for 12 h, and then filtered to remove the magnesium sulfate, yielding a mixed solution containing borate esters. The mixed solution was heated to 55 °C and subjected to vacuum distillation to remove the tetrahydrofuran. The solution was then washed with diethyl ether to obtain 1-(2-(3-methyl-5-vinylphenylethyl)-1,3,2-dioxaborane-4-yl)propyl acrylate (EDMP), a vinyl crosslinking monomer with a dynamic borate ester structure, in 80% yield (yield = 100% × actual yield of target product / theoretical yield of target product).

[0079] Preparation of degradable acrylate polymers with main / side chains containing sulfur esters and dynamic borate ester structures: 40 g of deionized water, 0.1 g of initiator ammonium persulfate (NH4PS, 1.0 wt.% vs monomers, the total mass of monomers being the sum of TDT monomers, EDMP monomers, and acrylate monomers) and 0.15 g of emulsifier sodium dodecylbenzenesulfonate (SDBS, 1.5 wt.% vs monomers, the total mass of monomers being the sum of TDT monomers, EDMP monomers, and acrylate monomers) were added to a 50 mL flask. The mixture was purged with argon for 30 min. Then, 1.3 g of TDT, 0.3 g of EDMP, and 8.4 g of acrylate monomers (4.2 g of methyl methacrylate and 4.2 g of ethyl acrylate) were added. The mixture was stirred at 250 rpm for 4 h at 80 °C to obtain the degradable acrylate polymer PA / TDT-EDMP (20 wt.%) with main / side chains containing sulfur esters and dynamic borate ester structures.

[0080] Example 3

[0081] A method for preparing a main / side chain degradable acrylate polymer PA / DMT-PDMP containing sulfur ester and dynamic borate ester structure includes the following steps:

[0082] Synthesis and purification of thioester monomers: 9.68 g of 3,3,5-trimethyldihydrofuran-2(3H)-one was dissolved in 90 mL of tetrahydrofuran, followed by the slow addition of 9.12 g of carbon disulfide reagent. The mixture was stirred under a nitrogen atmosphere, heated to 75 °C, and refluxed for 5 h. After the reaction, tetrahydrofuran was removed by rotary evaporation to obtain the reaction mixture. The optimal sample R to be separated was obtained by thin-layer chromatography. f The value was 0.3. At this point, the mobile phase ratio was petroleum ether (weakly polar solvent): ethyl acetate (strongly polar solvent) = 2:1. The above viscous liquid was separated by column chromatography using alumina as the adsorbent, yielding a clear solution. The clear solution was heated to 50℃ and the mobile phase solvent was removed by vacuum distillation to obtain the degradable monomer 3,3,5-trimethyldihydrofuran-2(3H)-thione (DMT) containing a sulfur ester bond, with a yield of 38% (yield = 100% × actual yield of target product / theoretical yield of target product).

[0083] Synthesis and purification of borate ester monomers: 50g of 4-(ethylene oxide-2-yl)but-2-yl acrylate and 0.05g of hydroquinone were added to 200g of aqueous solution containing 2g of sulfuric acid. The mixture was stirred at 80℃ for 4h and then cooled to room temperature. First, 4g of NaHCO3 was added to neutralize excess acid in the reaction, then 8g of sodium chloride was added to promote salting out, accelerate the separation of the aqueous and organic phases, inhibit the formation of the emulsion layer, and improve the extraction rate. The mixture was then extracted with 300mL of ethyl acetate, and the extraction was repeated three times. Then, 5g of anhydrous magnesium sulfate was added to remove water from the ethyl acetate. After removing the ethyl acetate by vacuum distillation, the resulting product was 5,6-dihydroxyhexane-2-yl acrylate, a colorless viscous liquid containing a vicinal diol structure. 14 g of (2-(4-vinylphenyl)propyl)boronic acid was dissolved in 300 mL of tetrahydrofuran. 18.4 g of 5,6-dihydroxyhexane-2-yl acrylate was slowly added dropwise, followed by 10 g of anhydrous magnesium sulfate. The mixture was stirred at room temperature for 12 h, and then filtered to remove the magnesium sulfate, yielding a clear mixed solution containing the borate ester. The mixed solution was heated to 45 °C and the organic solvent was removed by vacuum distillation to obtain a viscous liquid, which is the vinyl crosslinking monomer 4-(2-(2-(4-vinylphenyl)propyl)-1,3,2-dioxaborane-4-yl)butane-2-yl methacrylate (PDMP) with a dynamic borate ester structure, in a yield of 86% (yield = 100% × actual yield of target product / theoretical yield of target product).

[0084] Preparation of a main / side chain degradable acrylate polymer containing sulfur esters and dynamic borate ester structures: 40 g of deionized water, 0.15 g of initiator sodium persulfate (NaPS, 1.5 wt.% vs monomers, the total mass of monomers being the sum of DMT monomers, PDMP monomers, and acrylate monomers) and 0.15 g of emulsifier sodium dodecyl diphenyl ether disulfonate (SLDED, 1.5 wt.% vs monomers, the total mass of monomers being the sum of DMT monomers, PDMP monomers, and acrylate monomers) were added to a 50 mL flask. The mixture was purged with nitrogen for 20 min. Then, 1 g of DMT, 0.3 g of PDMP, and 8.7 g of acrylate monomers (4.5 g of methyl methacrylate and 4.2 g of tert-butyl acrylate) were added. The mixture was stirred at 250 rpm for 4 h at 70 °C to obtain a main / side chain degradable acrylate polymer PA / DMT-PDMP (20 wt.%) containing sulfur esters and dynamic borate ester structures.

[0085] Example 4

[0086] A method for preparing a main / side chain degradable acrylate polymer PA / EMPT-EMBP containing sulfur ester and dynamic borate ester structure includes the following steps:

[0087] Synthesis and purification of thioester monomers: 16.42 g of 4-ethyl-6-methyltetrahydro-2H-pyran-2-one was dissolved in 100 mL of toluene, followed by the slow addition of 24.22 g of Lawesson's reagent. The mixture was stirred under an argon atmosphere and heated to 115 °C under reflux for 6 h. After the reaction, toluene was removed by rotary evaporation to obtain a viscous liquid. The optimal sample R to be separated was obtained by thin-layer chromatography. f The value was 0.3. At this point, the mobile phase ratio was hexane (weakly polar solvent): dichloromethane (strongly polar solvent) = 3:1. The above viscous liquid was separated by column chromatography using silica gel powder as the adsorbent, yielding a clear solution. The clear solution was heated to 90℃ and the mobile phase solvent was removed by vacuum distillation to obtain the degradable monomer 4-ethyl-6-methyltetrahydro-2H-pyran-2-thione (EMPT) containing a sulfur ester bond, with a yield of 45% (yield = 100% × actual yield of target product / theoretical yield of target product).

[0088] Synthesis and purification of vinyl crosslinking monomers containing dynamic borate ester structures: 30 g of 1-(ethylene oxide-2-yl)propane-2-yl acrylate and 0.03 g of p-methoxyanisole were added to 200 g of aqueous solution containing 2.5 g of sulfuric acid, and ring-opening was performed via acid catalysis. The mixture was stirred at 80 °C for 2 h and then cooled to room temperature. First, 3 g of Na₂CO₃ was added to neutralize excess acid in the reaction, and then 5 g of sodium chloride was added to promote salting out, accelerate the separation of the aqueous and organic phases, inhibit the formation of the emulsion layer, and improve the extraction rate. The mixture was then extracted with 200 mL of ethyl acetate, and the extraction was repeated three times. 5 g of anhydrous magnesium sulfate was then added to remove water from the ethyl acetate. After removing the ethyl acetate by vacuum distillation, 4,5-dihydroxypentane-2-yl acrylate containing o-diol was obtained as a colorless viscous liquid.

[0089] 18 g of (3-vinylbenzyl)boronic acid was dissolved in 200 mL of tetrahydrofuran. 14.8 g of 4,5-dihydroxypent-2-yl acrylate was slowly added dropwise, followed by 10 g of anhydrous magnesium sulfate. The mixture was stirred at room temperature for 12 h, and then filtered to remove the magnesium sulfate, yielding a clear mixed solution containing the borate ester. The solution was heated to 50 °C and the organic solvent was removed by vacuum distillation. Unreacted reactants were then washed with diethyl ether to obtain the vinyl crosslinking monomer 1-(2-(3-vinylbenzyl)-1,3,2-dioxaborane-4-yl)propane-2-yl acrylate (EMBP) with a dynamic borate ester structure. The yield was 85% (yield = 100% × actual yield of target product / theoretical yield of target product).

[0090] Preparation of a main / side chain degradable acrylate polymer containing sulfur esters and dynamic borate ester structures: 40 g of deionized water, 0.2 g of initiator NaPS (2.0 wt.% vs. monomers, the total mass of monomers being the sum of EMPT monomers, EMBP monomers, and acrylate monomers) and 0.15 g of emulsifier SDBS (1.5 wt.% vs. monomers, the total mass of monomers being the sum of EMPT monomers, EMBP monomers, and acrylate monomers) were added to a 50 mL flask. The mixture was purged with argon for 25 min. Then, 0.9 g of EMPT, 0.3 g of EMBP, and 8.8 g of acrylate monomers (4.4 g of methyl methacrylate and 4.4 g of methyl acrylate) were added. The mixture was stirred at 250 rpm for 4 h at 75 °C to obtain a main / side chain degradable acrylate polymer PA / EMPT-EMBP (20 wt.%) containing sulfur esters and dynamic borate ester structures.

[0091] Comparative Example

[0092] A method for preparing a biodegradable acrylate crosslinked polymer PA / SDT-TGDE containing a non-dynamic covalent structure includes the following steps:

[0093] Synthesis and purification of thioester monomers: 8.44 g of dibenzo[c,e]oxetane-5(7H)-one was dissolved in 40 g of toluene, followed by the slow addition of 25.86 g of Lawesson's reagent. The mixture was stirred under a nitrogen atmosphere, heated to 115 °C, and refluxed for 5 h. Toluene was then removed by rotary evaporation to obtain a viscous liquid. The optimal sample R to be separated was obtained by thin-layer chromatography. f The value is 0.4. At this time, the ratio of the mobile phase is hexane (weakly polar solvent): dichloromethane (strongly polar solvent) = 1:2. The above viscous liquid is separated by column chromatography with silica gel powder as adsorbent. Then, the mobile phase solvent is removed by vacuum distillation to obtain the degradable monomer SDT containing sulfur ester bonds.

[0094] Preparation of a biodegradable acrylate crosslinking polymer containing non-dynamic covalent bonds: 40 g of deionized water, 0.15 g of initiator KPS (1.5 wt.% vs. monomer) and 0.2 g of emulsifier SDS (2.0 wt.% vs. monomer) were added to a 50 mL flask and purged with nitrogen for 20 min. Then, 0.8 g of SDT, 0.3 g of triethylene glycol divinyl ether (TGDE) and 8.9 g of acrylate monomers (4.5 g of methyl methacrylate and 4.4 g of butyl acrylate) were added. The mixture was stirred at 250 rpm for 4 h at 70 °C to obtain a biodegradable acrylate polymer PA / SDT-TGDE (20 wt.%) containing a non-dynamic covalent structure.

[0095] The Fourier transform infrared (FTIR) spectra of the PA / SDT-DVTB polymer in Example 1 and the comparative PA / SDT-TGDE polymer were tested, and the FTIR spectra are shown below. Figure 3 As shown: 1686cm -1 The stretching vibration peak at 1606 cm⁻¹, representing -SC=O, confirms the incorporation of the SDT monomer into the polymer backbone; -1 The peak at 1686 cm⁻¹ represents the stretching vibration of the boronic acid ester bond, confirming the incorporation of DVTB monomer into the polymer side chain, thus verifying the successful preparation of the PA / SDT-DVTB polymer. Correspondingly, the peak at 1686 cm⁻¹... -1 The stretching vibration peak at -SC=O confirms that the SDT monomer was successfully incorporated into the main chain of the polymer PA / SDT-TGDE, and that the polymer is insoluble in THF, indicating that the cross-linked structure was also successfully prepared.

[0096] GPC graphs of degradation products of PA / SDT-DVTB under different degradation conditions in Example 1 are shown below. Figure 4 As shown, under alkaline and ammonolytic conditions, the cross-linking structure of the PA / SDT-DVTB polymer is broken, and the polymer molecular weight decreases. The products obtained in Example 1 and the comparative example were subjected to degradation tests under alkaline and ammonolytic conditions in 0.1 mol / L KOH solution and 0.1 mol / L IPA solution, respectively. The results are shown in Table 1. In Example 1, the thioester bonds and dynamic borate ester structures in the PA / SDT-DVTB polymer were broken under alkaline and ammonolytic conditions, and the polymer cross-linking structure was broken into a linear structure, resulting in a decrease in polymer molecular weight. The number-average molecular weights of the PA / SDT-DVTB polymer after degradation under alkaline and ammonolytic conditions were 9346.4 g / mol and 7929.6 g / mol, respectively; the weight-average molecular weights of the PA / SDT-DVTB polymer after degradation under alkaline and ammonolytic conditions were 25796.1 g / mol and 18475.9 g / mol, respectively; and the polymer dispersity of the PA / SDT-DVTB polymer after degradation under alkaline and ammonolytic conditions were 2.765 and 2.334, respectively.

[0097] Degradation rate: The degradation rate measures the degree to which a substance decomposes or degrades under certain conditions. The formula for calculating the degradation rate is as follows: Degradation rate (%) = ((Initial weight - Final weight) / Initial weight) × 100%

[0098] The specific steps for calculating the degradation rate are as follows:

[0099] 1. Measure the initial weight: Accurately measure the initial weight of the test substance before testing.

[0100] 2. Degradation test: Place the test substance under degradation conditions for a certain period of time (the time is determined according to the degradation conditions).

[0101] 3. Measure the final weight: After the degradation experiment is completed, remove the test material and measure its final weight.

[0102] 4. Calculate the degradation rate: Calculate the degradation rate of the test substance according to the above formula.

[0103] The PA / SDT-DVTB polymer obtained in Example 1 achieved degradation rates of 90% and 99% under alkaline and ammonolysis conditions, respectively, after 24 hours. The degradation effect of the PA / SDT-DVTB polymer under ammonolysis conditions was better than that under alkaline conditions, indicating that the degradable structural units are more sensitive to ammonolysis. The comparative PA / SDT-TGDE polymer achieved degradation rates of less than 5% after 24 hours. A small number of degradable fragments originated from structures in the polymer that were not locked by cross-linking structures and whose thioester units on the main chain were degradable. However, over 95% of the degradation was due to being locked by non-degradable cross-linking structures. The experimental results show that the borate-containing PA / SDT-DVTB polymer can achieve a high degradation rate under mild conditions (low-concentration alkaline environment), which is beneficial for reducing environmental pollution caused by damaged and discarded materials.

[0104] Table 1. Degradation data (alkali hydrolysis-KOH and ammonolysis-IPA) for Example 1 and the comparative examples.

[0105]

[0106] The mechanical properties of PA / SDT-DVTB in Example 1 and PA / SDT-TGDE in Comparative Example were characterized using a universal testing machine. Figure 5 As shown: The tensile strength and elongation at break of the comparative PA / SDT-TGDE polymer were 3.27 MPa and 228.6%, respectively. The tensile strength and elongation at break of the PA / SDT-TGDE polymer in Example 1 reached 7.87 MPa and 403.7%, respectively. Its mechanical properties were significantly improved and were superior to those of the non-dynamically crosslinked TGDE polymer, indicating that the rigid structure of the DVTB crosslinked borate ester greatly improved the mechanical properties of the polymer.

[0107] Traditional acrylate polymers, due to their structural stability, are difficult to degrade in the environment, leading to serious plastic pollution problems. This invention prepares a chemically degradable PA / SDT-DVTB polymer containing thioester and dynamic borate ester structures. The chemical sensitivity of the thioester and dynamic borate ester structures in this polymer makes it easily degradable under mild conditions, reducing environmental pollution after material disposal. Furthermore, this invention significantly improves the mechanical properties of the PA / SDT-DVTB polymer through crosslinking of the dynamic borate ester monomer DVTB, giving it excellent mechanical properties suitable for a wide range of applications. This enhances material safety and reliability and extends its service life, far surpassing TGDE-crosslinked polymers. The degradable PA / SDT-DVTB polymer prepared by this invention exhibits excellent mechanical properties, making it suitable for high-precision instruments such as optoelectronic devices with mechanical performance requirements. The mild degradation conditions of the polymer facilitate the degradation of acrylate materials in the casing and internal structural components of optoelectronic devices such as printed circuit boards (PCBs), enabling the reuse of the circuit boards.

[0108] The embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a main / side chain biodegradable acrylate polymer containing sulfur esters and dynamic borate ester structures, characterized in that... Includes the following steps: 1) The lactone monomer is dissolved in an aqueous organic solvent, a sulfiding agent is added, and the mixture is stirred under an inert atmosphere for 5-8 h. The organic solvent is then removed, and the sulfide monomer dibenzo[c,e]oxetine-5(7H)-thion is obtained by chromatography. The lactone monomer is dibenzo[c,e]oxetine-5(7H)-one. 2) A vinyl monomer containing an epoxy functional group and a polymerization inhibitor are added to an aqueous sulfuric acid solution. The resulting mixture is stirred at 70-80°C for 2-4 h and cooled to room temperature. After neutralization, sodium chloride is added, the mixture is extracted, and after vacuum distillation, a vinyl monomer containing an ortho-diol structure is obtained. The obtained product is dissolved in an organic solvent, and boric acid monomers and anhydrous magnesium sulfate are added. The mixture is stirred at room temperature for 12-24 h, then heated to 40-60°C and vacuum distilled. After purification, a vinyl crosslinking monomer (2-(4-vinylphenyl)-1,3,2-dioxaborane-4-yl) methacrylate containing a dynamic borate ester structure is obtained. The vinyl monomer containing an epoxy functional group is glycidyl methacrylate, and the boric acid monomer is (4-vinylphenyl)boronic acid. 3) After mixing deionized water, initiator and emulsifier, replace the air under an inert atmosphere; add thioester monomer, vinyl crosslinking monomer with dynamic borate ester structure and acrylate monomer, mix and disperse ultrasonically, stir and react at 70-80°C to obtain a biodegradable acrylate polymer with main / side chain containing thioester and dynamic borate ester structure; the acrylate monomer is methyl methacrylate and butyl acrylate. The mass ratio of the thioester monomer to the acrylate monomer is 1:9-3:7; the mass ratio of the vinyl crosslinking monomer containing the dynamic borate ester structure and the thioester monomer to the acrylate monomer is 1:100-5:

100.

2. The method for preparing the main / side chain degradable acrylate polymer containing sulfur esters and dynamic borate ester structures according to claim 1, characterized in that: In step 1), the vulcanizing agent is one or more of Lawson's reagent, phosphorus pentasulfide, and carbon disulfide; the molar ratio of the lactone monomer to the vulcanizing agent is 1:0.5-1:

2.

3. The method for preparing the main / side chain degradable acrylate polymer containing sulfur esters and dynamic borate ester structures according to claim 1, characterized in that: In step 1), the organic solvent is one or more of tetrahydrofuran, benzene, and toluene, and the amount of organic solvent used per gram of lactone monomer is 10-50 mL; the reflux temperature is 5-10°C higher than the boiling point of the organic solvent used, and the organic solvent is removed by rotary evaporation under negative pressure at 40-60°C; the inert atmosphere is either nitrogen or argon. The chromatographic separation described herein is achieved by obtaining the optimal sample R to be separated using thin-layer chromatography. f The value is 0.2-0.4, and the separation is performed by column chromatography, wherein the volume ratio of the weakly polar solvent and the strongly polar solvent in the mobile phase is 1:1-4:1; the weakly polar solvent is one or more of pentane, petroleum ether and n-hexane; the strongly polar solvent is one or more of dichloromethane, ethyl acetate and methanol.

4. The method for preparing the main / side chain degradable acrylate polymer containing sulfur esters and dynamic borate ester structures according to claim 1, characterized in that: In step 2), the polymerization inhibitor is one or more of p-methoxyanisole, hydroquinone, 2,6-di-tert-butyl-p-cresol, and 2-tert-butyl-p-phenol; the mass ratio of the polymerization inhibitor to the boric acid monomer is 0.1:100-0.2:100; and the extractant is one or more of ethyl acetate, dichloromethane, and diethyl ether.

5. The method for preparing the main / side chain degradable acrylate polymer containing sulfur esters and dynamic borate ester structures according to claim 1, characterized in that: In step 2), the mass ratio of sulfuric acid to water in the sulfuric acid aqueous solution is 1:100-1.5:100; the addition of anhydrous magnesium sulfate is to remove water from the reaction and promote the forward reaction; the neutralization is carried out by adding an alkaline compound to control the pH to 7-7.5; the alkaline compound is one or more of Na2CO3, K2CO3 and NaHCO3; the addition of sodium chloride is to promote salting out; the mass ratio of sodium chloride to boric acid monomer is 1:10-1:

5.

6. The method for preparing the main / side chain degradable acrylate polymer with sulfur-containing ester and dynamic borate ester structure according to claim 5, characterized in that: In step 2), the molar ratio of anhydrous magnesium sulfate to boric acid monomer is 2:1-5:1; the organic solvent is one or more of ethyl acetate, dichloromethane, and diethyl ether, with 10-50 mL of organic solvent added per gram of boric acid monomer; the purification involves washing with a low-boiling-point solvent to remove unreacted raw materials; the mass ratio of boric acid monomer to low-boiling-point solvent is 1:9-1:2, and the low-boiling-point solvent is one or more of diethyl ether, petroleum ether, n-pentane, isopentane, and n-hexane; the low-boiling-point solvent is removed after standing at 20-40°C under negative pressure for 8-24 hours.

7. The method for preparing the main / side chain degradable acrylate polymer containing sulfur esters and dynamic borate ester structures according to claim 1, characterized in that: In step 3), the initiator is one or more of potassium persulfate, sodium persulfate, and ammonium persulfate; the emulsifier is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium dodecyl diphenyl ether disulfonate; the amount of initiator is 1%-2% of the total monomer mass, and the amount of emulsifier is 1%-2% of the total monomer mass; the total monomer mass is the sum of the masses of lactone monomer, crosslinking monomer containing dynamic borate ester structure, and acrylate monomer; the ultrasonic dispersion time is 10-20 min; the stirring speed is 200-300 rpm; the inert atmosphere is one of nitrogen or argon, and the inert atmosphere replacement time is 20-40 min.

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