A method for the electrochemical polymerization of polyether / polyester-polyether random copolymers
By using an electrochemical polymerization method and magnesium and platinum electrodes to regulate the copolymerization of lactones and epoxides, the problems of high selectivity and high purification cost of metal catalysts have been solved, and safe and efficient preparation of polyester-polyether random copolymers has been achieved, which has good application prospects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NORTHWEST NORMAL UNIVERSITY
- Filing Date
- 2024-12-23
- Publication Date
- 2026-04-17
AI Technical Summary
In the prior art, metal catalysts have selectivity problems and high purification costs when preparing polyester-polyether random copolymers, and there are no reports on the preparation of polyether/polyester-polyether random copolymers by electrochemical polymerization.
An electrochemical polymerization method was adopted, using a magnesium electrode as the anode and a platinum electrode as the cathode. The ring-opening copolymerization reaction of lactone and epoxide was regulated by electrical energy, avoiding the use of metal catalysts. The activity and ratio of the polymerizing monomers were adjusted to prepare polyester-polyether random copolymers with controllable molecular weight and molecular weight distribution index.
This method achieves a pollution-free and safe polymerization process, simplifies catalyst screening and impurity removal steps, improves the safety and efficiency of the polymerization reaction, and produces polyester-polyether random copolymers with controllable molecular weight and molecular weight distribution index.
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Figure CN119640278B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer preparation technology and relates to a method for preparing polyester-polyether random copolymers by electrochemically controlling the copolymerization of lactones and epoxides. Background Technology
[0002] Polyethers possess unique chemical and physical properties, making them widely used in industrial and scientific research fields. However, in humid environments, polyether materials absorb moisture, expand, deform, and experience performance degradation, limiting their application in specific environments. Polyester-polyether random copolymers, combining the properties of both polyesters and polyethers, can be applied in food packaging, biomedicine, and medical devices. Currently, polyester-polyether random copolymers are mainly synthesized by adjusting the copolymerization activity of lactones and epoxides using metal catalysts. The metal catalysts used include organoaluminum, organozinc, Cr (salen) bicomponent catalysts, Co-Zn or Co-Al bimetallic complexes, and rare earth indium complexes. The catalyst system is primarily a metal complex, which not only presents the problem of monomer selectivity but also increases the purification cost of the copolymerization product. Therefore, developing a simple and efficient method for ring-opening copolymerization of lactones and epoxides is of great significance for the preparation of various polyester-polyether copolymers.
[0003] Electrochemical polymerization can regulate the activity of monomers by adjusting their redox potential, thereby controlling the copolymerization activity and ultimately regulating the polymer structure and composition. To date, no research has been reported on the preparation of polyether / polyester-polyether random copolymers using electrochemical polymerization. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing polyether / polyester-polyether random copolymers by electrochemical polymerization without the use of metal catalysts.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing polyether / polyester-polyether random copolymers by electrochemical polymerization, comprising the following steps:
[0006] 1) Take a dry electrolytic cell equipped with a magnetic stir bar, add conductive salt, install an anode electrode and a cathode electrode on the electrolytic cell, evacuate the electrolytic cell, and add tetrahydrofuran and dry epoxide using a syringe.
[0007] Each 0.3g of conductive salt requires 5-10mL of tetrahydrofuran and 0.1-2mL of epoxide;
[0008] Alternatively, take a dry electrolytic cell equipped with a magnetic stirrer, add a conductive salt and lactone monomer, install an anode electrode and a cathode electrode on the electrolytic cell, and after evacuating the electrolytic cell, add a dry epoxide using a syringe.
[0009] Each 0.3g of conductive salt requires 5-10mmol of lactone monomer and 5-10mL of epoxide;
[0010] Alternatively, take a dry electrolytic cell equipped with a magnetic stirrer, add a conductive salt and lactone monomer, install an anode electrode and a cathode electrode on the electrolytic cell, and after evacuating the electrolytic cell, add tetrahydrofuran and dry epoxide using a syringe.
[0011] Each 0.3g of conductive salt requires 5-10mmol of lactone monomer, 4-9mL of tetrahydrofuran, and 1-5mL of epoxide.
[0012] 2) At room temperature, after passing a constant current of 3-10 mA through an electrolytic cell for 1-15 hours, water or anhydrous methanol is added to the electrolytic cell for sedimentation. The sediment is dried in a vacuum oven at 60°C for 24 hours to obtain a polyester-polyether random copolymer.
[0013] The conductive salt used is tetrabutylammonium tetrafluoroborate.
[0014] The lactone monomers used are δ-valerolactone, ε-caprolactone, or L-lactide.
[0015] The epoxide is one or two of ethylene oxide, propylene oxide, cyclohexane oxide, epichlorohydrin, styrene oxide, allyl glycidyl ether, and tetrahydrofuran.
[0016] The anode electrode is a magnesium electrode, and the cathode electrode is a platinum electrode.
[0017] The polymerization method of this invention uses an electrochemical polymerization system with a magnesium electrode as the anode and a platinum electrode as the cathode. The lactone and epoxide monomers undergo ring-opening polymerization simultaneously under the action of electrical energy; that is, an electrochemically controlled ring-opening copolymerization method is employed, which reduces the difference in reactivity between the epoxide and lactone ring-opening polymerizations. By adjusting the amount of monomers and the reaction time, the proportion of polyester and polyether components in the copolymer can be effectively controlled, synthesizing polyether / polyester-polyether random copolymers with molecular weights of 10 kg / mol to 45 kg / mol and molecular weight distribution indexes of 1.10 to 1.30.
[0018] This invention relates to an electrochemical polymerization method, which uses clean energy (electricity) and does not pollute the environment. It eliminates the need for chemical catalysts and initiators, avoids catalyst screening and polymer impurity removal, and avoids the high-temperature reaction conditions required for polyester-polyether synthesis. This effectively improves the safety of the polymerization reaction and has promising application prospects. Attached Figure Description
[0019] Figure 1 These are P(PO-) prepared at different reaction times in Example 1. co The hydrogen NMR spectrum of 1H NMR (-THF).
[0020] Figure 2 These are P(PO-) prepared at different reaction times in Example 1. co GPC combination diagram of -THF).
[0021] Figure 3 P(LA-) prepared by reacting at different times in Example 2 co The hydrogen NMR spectrum of PO₄.
[0022] Figure 4 P(LA-) prepared by reacting at different times in Example 2 co GPC combination diagram of -PO).
[0023] Figure 5 P(LA-) prepared by reacting at different times in Example 3 co -PO- co The hydrogen NMR spectrum of 1H NMR (-THF).
[0024] Figure 6 P(LA-) prepared by reacting at different times in Example 3 co -PO- co GPC combination diagram of -THF).
[0025] Figure 7 The P(LA-) prepared by the reaction in Example 4 co -PO- co -THF purified product 1H NMR spectrum. Detailed Implementation
[0026] The present invention will be further described below with reference to specific embodiments and accompanying drawings. Unless otherwise stated, the terminology used in this invention generally has the meanings commonly understood by those skilled in the art. In the following embodiments, various processes and methods not described in detail are conventional methods known in the art. Furthermore, due to the diversity of polymer structures and proportions, not all preparation methods are described in detail; typical examples are used to illustrate the specific process steps of the present invention.
[0027] Example 1
[0028] Five dry electrolytic cells, each equipped with a magnetic stirrer, were prepared. 0.3 g of Bu4NBF4 was added to each cell, and electrodes were installed on each cell (magnesium electrode as the anode and platinum electrode as the cathode). After evacuating all cells for 30 minutes, 6 mL of dry tetrahydrofuran (THF) and 0.25 mL of propylene oxide (PO) were added to each cell using a syringe.
[0029] Then, at room temperature, a constant current of 4 mA was passed through each of the five electrolytic cells to carry out the electropolymerization reaction:
[0030] The electropolymerization reaction in the first electrolytic cell lasted for 2 hours; the electropolymerization reaction in the second electrolytic cell lasted for 3 hours; the electropolymerization reaction in the third electrolytic cell lasted for 4 hours; the electropolymerization reaction in the fourth electrolytic cell lasted for 5 hours; and the electropolymerization reaction in the fifth electrolytic cell lasted for 6 hours.
[0031] After the reaction was completed, water was added to each electrolytic cell for sedimentation. The sediment was then vacuum dried at 60°C for 24 hours to obtain five random copolymers of PO and THF (P(PO- co -THF).
[0032] The reaction process in Example 1 is as follows:
[0033]
[0034] Figure 1 These are five samples of P(PO-) prepared at different reaction times in Example 1. co The 1H NMR spectrum of -THF ( 1 H-NMR (CDCl3) image.
[0035] Figure 2 These are five samples of P(PO-) prepared at different reaction times in Example 1. co GPC combination diagram of -THF). Figure 2 It can be seen that as the polymerization reaction time increases, the conversion rates of PO and THF gradually increase, the molecular weight of the polymer increases, and the molecular weight distribution index does not change much, indicating that the polymerization method of the present invention has good control over the molecular weight and molecular weight distribution index of the polymer.
[0036] Example 2
[0037] Seven dry electrolytic cells, each equipped with a magnetic stirrer, were prepared. 0.3 g of Bu4NBF4 and 1 g (7 mmol) of L-lactide (LA) were added to each cell. All cells were equipped with electrodes (magnesium electrode as the anode and platinum electrode as the cathode). After evacuating all cells for 30 min, 6 mL of dry propylene oxide was added to each cell using a syringe.
[0038] Then, at room temperature, a constant current of 4 mA was passed through each of the seven electrolytic cells to carry out the electropolymerization reaction:
[0039] The electropolymerization reaction in the first electrolytic cell lasted for 1 hour, the second electrolytic cell for 2 hours, the third electrolytic cell for 3 hours, the fourth electrolytic cell for 4 hours, the fifth electrolytic cell for 5 hours, the sixth electrolytic cell for 6 hours, and the seventh electrolytic cell for 7 hours.
[0040] After the reaction was completed, anhydrous methanol was added to each of the seven electrolytic cells for precipitation. The precipitates were then vacuum dried at 60°C for 24 hours to obtain a random copolymer of PO and LA (P(LA- co -PO)).
[0041] The reaction process in Example 2 is as follows:
[0042]
[0043] Figure 3 P(LA-) prepared by reacting at different times in Example 2 co 1H NMR spectrum of -PO 1 H-NMR (CDCl3) image.
[0044] Figure 4 P(LA-) prepared by reacting at different times in Example 2 co GPC combination diagram of -PO). Figure 4 The results show that as the polymerization reaction time increases, the conversion rates of PO and LA gradually increase, the molecular weight of the polymer increases, and the molecular weight distribution index does not change much, indicating that the polymerization method of the present invention has good control over the molecular weight and molecular weight distribution index of the polymer.
[0045] Example 3
[0046] Take six dry electrolytic cells, each equipped with a magnetic stirrer, and add 0.3 g of Bu4NBF4 and 1 g of LA to each cell. Install electrodes on all cells (magnesium electrode as anode and platinum electrode as cathode). After evacuating all cells for 30 min, add 2 mL of dry propylene oxide and 5 mL of tetrahydrofuran to each cell using a syringe.
[0047] Then, at room temperature, a constant current of 4 mA was passed through each of the six electrolytic cells to carry out the electropolymerization reaction:
[0048] The electropolymerization reaction in the first electrolytic cell lasted for 2 hours, the second electrolytic cell for 3 hours, the third electrolytic cell for 4 hours, the fourth electrolytic cell for 5 hours, the fifth electrolytic cell for 6 hours, and the sixth electrolytic cell for 7 hours.
[0049] After the reaction was completed, anhydrous methanol was added to each electrolytic cell for precipitation. The precipitate was then vacuum dried at 60°C for 24 hours to obtain a random copolymer of PO, THF, and LA (P(LA- co -PO- co -THF).
[0050] The reaction process in Example 3 is as follows:
[0051]
[0052] Figure 5 The P(LA-) prepared at different reaction times in Example 3 co -PO- co The 1H NMR spectrum of -THF ( 1 H-NMR (CDCl3) image.
[0053] Figure 6 The P(LA-) prepared at different reaction times in Example 3 co -PO- co GPC combination diagram of -THF). Figure 6 The results show that as the polymerization reaction time increases, the conversion rates of PO, THF, and LA gradually increase, the molecular weight of the polymer increases, and the molecular weight distribution index does not change much, indicating that the polymerization method of the present invention has good control over the molecular weight and molecular weight distribution index of the polymer.
[0054] Example 4
[0055] A dry electrolytic cell equipped with a magnetic stirrer was used. 0.3 g of Bu4NBF4 and 1 g of LA were added. Electrodes were installed on the electrolytic cell (magnesium electrode as the anode and platinum electrode as the cathode). After evacuating the electrolytic cell for 30 min, 1 mL of dry propylene oxide and 6 mL of tetrahydrofuran were added to the cell using a syringe. Then, at room temperature, a constant current of 4 mA was passed through the electrolytic cell for electropolymerization for 7 h. After the reaction was completed, water was added to the electrolytic cell for sedimentation. The sediment was then vacuum-dried at 60 °C for 24 h to obtain a random copolymer of PO, THF, and LA (P(LA- co -PO- co -THF).
[0056] Example 4 demonstrates that, compared to Example 3, adjusting the amounts of propylene oxide and tetrahydrofuran does not diminish the applicability of the polymerization method of this invention. The polymer synthesized in Example 4 was structurally characterized. Figure 7 The 1H NMR spectrum shown clearly reveals NMR signal peaks linked by ester-ether bonds, indicating that the random copolymer of PO, THF, and LA (P(LA-) co -PO- co -THF) was successfully prepared.
Claims
1. A method for preparing polyether / polyester-polyether random copolymers by electrochemical polymerization, characterized in that, The polyether random copolymer is prepared as follows: 1) Take a dry electrolytic cell equipped with a magnetic stir bar, add conductive salt, install the anode and cathode electrodes on the electrolytic cell, evacuate the electrolytic cell, and add tetrahydrofuran and dry epoxide using a syringe; for every 0.3g of conductive salt, 5-10mL of tetrahydrofuran and 0.1-2mL of epoxide are required. 2) At room temperature, after passing a constant current of 3-10 mA through an electrolytic cell for 1-15 hours, water or anhydrous methanol is added to the electrolytic cell for sedimentation. The sediment is dried in a vacuum oven at 60°C for 24 hours to obtain a polyether random copolymer. The polyester-polyether random copolymer is prepared as follows: 1) Take a dry electrolytic cell equipped with a magnetic stir bar, add conductive salt and lactone monomer, install anode and cathode electrodes on the electrolytic cell, evacuate the electrolytic cell, and add dry epoxide using a syringe; for every 0.3g of conductive salt, 5-10mmol lactone monomer and 5-10mL epoxide are required. Alternatively, take a dry electrolytic cell equipped with a magnetic stirrer, add conductive salt and lactone monomer, install an anode electrode and a cathode electrode on the electrolytic cell, evacuate the electrolytic cell, and add tetrahydrofuran and dry epoxide using a syringe; for every 0.3g of conductive salt, 5-10mmol lactone monomer, 4-9mL tetrahydrofuran and 1-5mL epoxide are required. 2) At room temperature, after passing a constant current of 3-10 mA through an electrolytic cell for 1-15 hours, water or anhydrous methanol is added to the electrolytic cell for sedimentation. The sediment is dried in a vacuum oven at 60°C for 24 hours to obtain a polyester-polyether random copolymer.
2. The method for preparing polyether / polyester-polyether random copolymers by electrochemical polymerization as described in claim 1, characterized in that, The conductive salt is tetrabutylammonium tetrafluoroborate.
3. The method for preparing polyether / polyester-polyether random copolymers by electrochemical polymerization as described in claim 1, characterized in that, The lactone monomer is δ-valerolactone, ε-caprolactone, or L-lactide.
4. The method for preparing polyether / polyester-polyether random copolymers by electrochemical polymerization as described in claim 1, characterized in that, The epoxide is at least one selected from ethylene oxide, propylene oxide, cyclohexane oxide, epichlorohydrin, styrene oxide, and allyl glycidyl ether.
5. The method for preparing polyether / polyester-polyether random copolymers by electrochemical polymerization as described in claim 1, characterized in that, The anode electrode is a magnesium electrode, and the cathode electrode is a platinum electrode.