A fully oxygen tolerant reversible complex-mediated polymerization process

Abstract

The application discloses a kind of completely oxygen-tolerant reversible complex-mediated polymerization method, including under the condition of complete opening, polymerization monomer, alkyl iodide and tertiary amine are dissolved in organic solvent, then the obtained mixed solution is placed in constant temperature water bath, and polymerization reaction is carried out under visible light condition;The molar ratio of alkyl iodide and tertiary amine is 1:1;During polymerization, under visible light stimulation, alkyl iodide is in excited state, tertiary amine loses an electron, oxygen gets electron and becomes superoxide radical, then quenches, and alkyl iodide further initiates the polymerization of polymerization monomer, thereby realizing completely oxygen-tolerant controllable room temperature RCMP polymerization.The application consumes oxygen by alkyl iodide and tertiary amine together, on the one hand, no need of deoxygenation operation, develop completely oxygen-tolerant RCMP polymerization method, on the other hand, in addition to polymerization monomer, alkyl iodide and tertiary amine, no other reagent is needed, and no metal is needed, use the tertiary amine with low price, and good practicability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of free radical polymerization, and particularly relates to a completely oxygen-tolerant reversible complex-mediated polymerization method. BACKGROUND

[0002] Reversible deactivation radical polymerization (RDRP), including atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization, nitroxide-mediated polymerization (NMP), and reversible complex-mediated polymerization (RCMP), can be successfully used to prepare a variety of polymer materials with controlled molecular weight, narrow molecular weight distribution, and various topologies. However, traditional RDRP usually needs to be carried out in an oxygen-free atmosphere, because oxygen (O2) is a radical scavenger that can quickly quench propagating radicals, resulting in the loss of control over molecular weight and molecular weight distribution. In order to overcome this limitation, a lot of efforts have been devoted to developing oxygen-tolerant ATRP and RAFT polymerization, so that the polymerization does not need to be deoxygenated in advance. For example, various redox-active catalysts are added in RDRP to remove oxygen.

[0003] Compared with ATRP and RAFT polymerization, reversible complex-mediated polymerization (RCMP) using alkyl iodide (R-I) as an initiator and tertiary amine (TAs) and salt as a catalyst has attracted more and more attention due to its distinctive characteristics such as mild conditions, wide monomer versatility, absence of transition metal catalysts and odoriferous compounds. Although the unstable C-I bond of alkyl iodide brings challenges due to its relatively low bond dissociation energy (BDE), an in situ bromine-iodine transformation strategy is successfully developed by halogen exchange reaction of alkyl bromide (R-Br) with sodium iodide (NaI), thereby achieving excellent control over polymerization. However, it should be noted that deoxygenation is required before polymerization in most cases, and currently there are few studies on completely oxygen-tolerant RCMP.

[0004] It is well known that tertiary amines (TAs) are widely used as ligands or catalysts in ATRP and RAFT polymerization due to their special electronic structure. In the case of oxygen-tolerant RDRP, TAs used as reducing agents or co-catalysts can consume oxygen through photo-induced electron transfer. SUMMARY

[0005] In view of the problems existing in the prior art, the present application provides a completely oxygen-tolerant reversible complex-mediated polymerization method, which consumes oxygen through tertiary amines, generates primary radicals through alkyl iodide, and thus can successfully achieve controlled reversible complex-mediated polymerization without metal.

[0006] To solve the above technical problems, the present application realizes the following technical scheme:

[0007] A completely oxygen-tolerant reversible complex-mediated polymerization method comprises the following steps:

[0008] In the condition of completely open, the polymerization monomer, alkyl iodide and tertiary amine are dissolved in organic solvent, and then the obtained mixed solution is placed in a constant temperature water bath, and the polymerization reaction is carried out under visible light; the molar ratio of the alkyl iodide to the tertiary amine is 1:1; during the polymerization reaction, under the stimulation of visible light, the alkyl iodide is in the excited state as an initiator, the tertiary amine loses an electron, and oxygen gets an electron to become a superoxide free radical which is then quenched, and the alkyl iodide further initiates the polymerization of the polymerization monomer, thereby realizing completely oxygen-tolerant visible light-induced room temperature reversible complexation-mediated polymerization (RCMP), and by controlling the on-off of visible light, the completely oxygen-tolerant light-switchable reversible complexation-mediated polymerization (RCMP) can also be realized.

[0009] Further, the polymerization monomer can be methyl methacrylate (MMA).

[0010] Further, the alkyl iodide is directly purchased, and a reversible complexation-mediated polymerization initiator such as 2-iodo-2-methylpropionitrile (CP-I) can be used.

[0011] Further, the alkyl iodide is obtained by nucleophilic substitution of bromine-iodine transfer from an alkyl bromide and an iodine salt, wherein the alkyl bromide as a bromine-iodine transfer initiator can use α-bromomethyl benzoate (MBPA) or α-bromoethyl benzoate (EBPA), and the iodine salt can use sodium iodide (NaI) or tetrabutylammonium iodide (TBAI).

[0012] Further, the tertiary amine can use one of pentamethyldiethylenetriamine (PMDETA), (tris[2-(dimethylamino)ethyl]amine) (Me6TREN) or tetramethylethylenediamine (TMEDA).

[0013] Further, the organic solvent can use one of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC) or tetrahydrofuran (THF).

[0014] Further, the temperature of the constant temperature water bath during the polymerization reaction is 25℃, and the reaction time is 5-24h.

[0015] Further, the polymerization reaction is carried out in a completely open ampoule.

[0016] Further, the visible light can use a 12W, 4mW / cm 2 LED lamp.

[0017] Further, the molecular weight distribution of the polymer obtained by the polymerization reaction is <1.42.

[0018] Generally, iodine radicals tend to recombine with another radical to form iodine molecule / solvent complex (I2 / solvent). In addition, a characteristic red-yellow color can be seen after polymerization. Spin adducts with DMPO were found to be captured superoxide radicals, which indicated that oxygen can be reduced to superoxide radical anion in the presence of CP-I and PMDETA, so that the polymerization occurred in air.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] The polymerization method of the present application consumes oxygen by alkyl iodide and tertiary amine together, the alkyl iodide can generate primary radicals under visible light stimulation, and the green controllable RCMP is successfully developed under the regulation of tertiary amine, on the one hand, it can be carried out in the presence of oxygen without oxygen removal operation, and a completely oxygen-tolerant RCMP polymerization method is developed, on the other hand, in addition to the polymerization monomer, alkyl iodide and tertiary amine, no other reagent is needed, and no metal is needed, the tertiary amine with low price is used, and the practical applicability of the system is enhanced.

[0021] The above description is only a summary of the technical scheme of the present application, in order to more clearly understand the technical means of the application, and the content of the specification can be implemented, the following will be described in detail with the preferred embodiments of the present application and the accompanying drawings. The specific embodiments of the present application are given in detail by the following examples and their accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application, the schematic embodiments of the present application and their description are used to explain the present application, and do not constitute improper limitation on the present application. In the drawings:

[0023] Figure 1 The graph is the polymerization kinetics curve of the light-induced MMA by bromine-iodine transfer initiation of test example 1 of the present application.

[0024] Figure 2 The graph is the polymerization kinetics curve of the light-induced MMA by CP-I initiation of test example 2 of the present application.

[0025] Figure 3 The graph is the GPC elution curve of PMMA before and after chain extension in test example 3 and test example 4 of the present application.

[0026] Figure 4 The graph is the possible mechanism of the completely oxygen-tolerant reversible complex-mediated polymerization method of the present application. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present application will be described in detail below with reference to the attached drawings. It should be understood that the embodiments shown in the drawings are merely intended to illustrate the essential spirit of the application and should not be construed to limit the scope of the application.

[0028] In the following description, for purposes of explanation and not limitation, specific details are set forth, such as a description of various embodiments in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that the embodiments can be practiced in different manners without one or more of the specific details.

[0029] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an overly literal sense unless expressly so defined herein.

[0030] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0031] As used in this specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the content clearly dictates otherwise. It should be noted that the term "comprising" as used in this specification and the appended claims is inclusive or open and does not exclude other unrecited elements or method steps.

[0032] Furthermore, the technical features involved in the different embodiments of the application described below can be combined with each other as long as there is no conflict. Unless otherwise specified, the reagents and materials used in the present application are commercially available.

[0033] The present application provides a completely oxygen-tolerant reversible complex-mediated polymerization method, comprising the following steps:

[0034] First, under completely open conditions, such as in a completely open ampoule, the polymerization monomer, alkyl iodide and tertiary amine are dissolved in an organic solvent, and stirred uniformly to obtain a mixed solution.

[0035] Preferably, the molar ratio of the alkyl iodide to the tertiary amine is 1:1.

[0036] Preferably, the organic solvent can be one of dimethyl sulfoxide (DMSO), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAC) or tetrahydrofuran (THF).

[0037] Preferably, the polymerizable monomer can be methyl methacrylate (MMA).

[0038] Preferably, the tertiary amine can be one of pentamethyldiethylenetriamine (PMDETA), (tris[2-(dimethylamino)ethyl]amine) (Me6TREN) or tetramethylethylenediamine (TMEDA).

[0039] The alkyl iodide can be directly purchased or obtained by nucleophilic substitution of bromine-iodine transfer from alkyl bromide and iodine salt.

[0040] For example, the alkyl iodide can be an existing reversible complex mediated polymerization initiator, such as 2-iodo-2-methylpropionitrile (CP-I).

[0041] When the alkyl iodide is obtained by bromine-iodine transfer, the alkyl bromide, as the bromine-iodine transfer initiator, can be preferably methyl α-bromophenylacetate (MBPA) or ethyl α-bromophenylacetate (EBPA), and the iodine salt can be preferably sodium iodide (NaI) or tetrabutylammonium iodide (TBAI).

[0042] Then, the completely open ampoule containing the mixed solution is placed in a constant temperature water bath at 25℃, and the polymerization reaction is carried out under visible light, such as the irradiation of a 12W, 4mW / cm 2 The molecular weight distribution of the obtained polymer is <1.42.

[0043] During the polymerization reaction, under the visible light stimulus, the alkyl iodide is in an excited state as an initiator, the tertiary amine loses an electron, and oxygen gets an electron to become a superoxide radical which is then quenched, and the alkyl iodide further initiates the polymerization of the polymerizable monomer, thereby realizing completely oxygen-tolerant visible light-induced room temperature RCMP polymerization, and by controlling the switch of visible light, completely oxygen-tolerant light-switchable RCMP polymerization can also be realized.

[0044] The polymerization method and polymerization effect of the present application are described in detail below through multiple examples and test examples.

[0045] Example 1

[0046] The polymerization method of light-induced, pentamethyldiethylenetriamine (PMDETA), methyl α-bromophenylacetate (MBPA) and sodium iodide (NaI) generated alkyl iodide as an initiator, specifically includes the following steps:

[0047] The raw materials were taken in a 2 mL ampoule in a molar ratio of [MMA]0:[CP-I]0:[PMDETA]0= 100:1:1 and 0.5 mL of N,N-dimethylacetamide (DMAC) was added as a reaction solvent. The reaction was carried out under visible light irradiation (12 W, 4 mW / cm 2 ) until the ampoule broke at the prescribed time, the polymerization solution was diluted with tetrahydrofuran, the diluted polymerization solution was dropped into 250 mL of methanol, precipitated, and suction filtered. The obtained polymer was dried in a vacuum drying oven until the weight became constant.

[0048] Example 2

[0049] The polymerization method using light induction, pentamethyldiethylenetriamine (PMDETA), and 2-iodo-2-methylpropionitrile (CP-I) as an initiator included the following steps:

[0050] The raw materials were taken in a 2 mL ampoule in a molar ratio of [MMA]0:[CP-I]0:[PMDETA]0= 100:1:1 and 0.5 mL of N,N-dimethylacetamide (DMAC) was added as a reaction solvent. The reaction was carried out under visible light irradiation (12 W, 4 mW / cm 2 ) until the ampoule broke at the prescribed time, the polymerization solution was diluted with tetrahydrofuran, the diluted polymerization solution was dropped into 250 mL of methanol, precipitated, and suction filtered. The obtained polymer was dried in a vacuum drying oven until the weight became constant.

[0051] Example 3

[0052] The polymerization method using light induction, methyl α-bromophenylacetate (MBPA), and sodium iodide (NaI) to generate an alkyl iodide as an initiator, and different tertiary amines such as tris[2-(dimethylamino)ethyl]amine (Me6TREN) or tetramethylethylenediamine (TMEDA) for regulation included the following steps:

[0053] The raw materials were taken in a 2 mL ampoule in a molar ratio of [MMA]0:[MBPA]0:[NaI]0:[Me6TREN / TMEDA]= 200:1:4:1 and 0.5 mL of N,N-dimethylacetamide (DMAC) was added as a reaction solvent. The reaction was carried out under visible light irradiation (12 W, 4 mW / cm 2 ) until the ampoule broke at the prescribed time, the polymerization solution was diluted with tetrahydrofuran, the diluted polymerization solution was dropped into 250 mL of methanol, precipitated, and suction filtered. The obtained polymer was dried in a vacuum drying oven until the weight became constant.

[0054] Example 4

[0055] A polymerization method using photo-induced polymerization, with tris[2-(dimethylamino)ethyl]amine (Me6TREN) or tetramethylethylenediamine (TMEDA), 2-iodo-2-methylpropionitrile (CP-I) as initiators and different tertiary amines as regulators, specifically includes the following steps:

[0056] According to the molar ratio of [MMA]0:[CP-I]0:[Me6TREN / TMEDA]0 = 100:1:1, the raw materials were taken into a 2 mL ampoule, and 0.5 mL of N,N-dimethylacetamide (DMAC) was added as a reaction solvent. Under the condition that the ampoule was completely open, the reaction was carried out under visible light irradiation (12 W, 4 mW / cm²). 2 The reaction was carried out for a specified time, then the tube was broken. The polymerization solution was diluted with tetrahydrofuran, and the diluted polymer solution was added dropwise to 250 mL of methanol to precipitate. The precipitate was then filtered. The resulting polymer was dried in a vacuum drying oven until constant weight was achieved.

[0057] Test Example 1

[0058] kinetic verification of the polymerization reaction:

[0059] (1) After numbering the five ampoules, the following treatment was performed: MMA (468 mg, 4.67 mmol), MBPA (5.4 mg, 0.023 mmol), PMDETA (4.1 mg, 0.023 mmol), NaI (14.0 mg, 0.093 mmol) and 0.5 mL of DMAC reaction solvent were added to the 2 mL ampoules.

[0060] (2) In a 25℃ constant temperature water bath and with visible light (12W, 4mW / cm²), 2 The polymerization system was controlled in real time under irradiation. The same temperature conditions were repeatedly applied in parallel group experiments to investigate the polymer. The reaction time interval was 4 hours.

[0061] (3) After the reaction has reached the set time, turn on the tube and add an appropriate amount of tetrahydrofuran (THF) to dilute the polymerization solution. Drop the diluted polymerization solution into 250 mL of methanol, precipitate, and filter. Place the obtained polymer in a vacuum drying oven and dry until constant weight.

[0062] See Figure 1 As shown, Figure 1 The photo-induced RCMP polymerization kinetics of alkyl iodides provided by MBPA and NaI for MMA show that the polymer chains grow in an orderly manner with increasing reaction time. The molecular weight distribution indicates that this polymerization reaction is well controlled.

[0063] Test Example 2

[0064] kinetic verification of the polymerization reaction:

[0065] (1) After numbering the five ampoules, the following treatment was performed: MMA (468 mg, 4.67 mmol), CP-I (9.1 mg, 0.047 mmol), PMDETA (4.1 mg, 0.023 mmol) and 0.5 mL of DMAC reaction solvent were added to the 2 mL ampoules.

[0066] (2) In a 25℃ constant temperature water bath and with visible light (12W, 4mW / cm²), 2 The polymerization system was controlled in real time under irradiation. The same temperature conditions were repeatedly applied in parallel group experiments to investigate the polymer. The reaction time interval was 1 hour.

[0067] (3) After the reaction has reached the set time, turn on the tube and add an appropriate amount of tetrahydrofuran (THF) to dilute the polymerization solution. Drop the diluted polymerization solution into 250 mL of methanol, precipitate, and filter. Place the obtained polymer in a vacuum drying oven and dry until constant weight.

[0068] See Figure 2 As shown, Figure 2 The figure shows the photo-induced kinetics of oxygen-resistant RCMP polymerization initiated by CP-I with MMA. The results show that the polymer chains grow in an orderly manner with increasing reaction time. The molecular weight distribution indicates that this polymerization reaction is well controlled.

[0069] As shown in Table 1, which presents oxygen-resistant RCMP regulated by different tertiary amines, it can be seen from Table 1 that tertiary amines affect the time and conversion rate of free radical polymerization.

[0070] Table 1

[0071]

[0072] Test Example 3

[0073] The chain extension reaction of PMMA (the PMMA used was prepared using the method in Test Example 1) specifically includes the following steps:

[0074] (1) Weigh MMA (468 mg, 4.67 mmol), PMMA (149.0 mg, 0.023 mmol), NaI (14.0 mg, 0.093 mmol), and PMDETA (4.1 mg, 0.023 mmol) into a 2 mL ampoule, and then add 0.5 mL of DMAC as the reaction solvent.

[0075] (2) Place the ampoule containing the solution under visible light to carry out the polymerization reaction.

[0076] (3) After the reaction has proceeded for 5 hours, the tube is opened and an appropriate amount of tetrahydrofuran (THF) is added to dilute the polymerization solution. The diluted polymerization solution is then dropped into 30 mL of anhydrous methanol to precipitate, and the precipitate is filtered. The resulting polymer is then dried in a vacuum drying oven until constant weight is achieved.

[0077] See Figure 3 As shown, Figure 3 The graph shows the GPC effluent curves before and after PMMA chain extension. Figure 3 As can be seen, the polymerized PMMA still retains its activity.

[0078] Test Example 4

[0079] The chain extension reaction of PMMA (the PMMA used was prepared using the method in Test Example 1) specifically includes the following steps:

[0080] (1) Weigh MMA (234 mg, 2.34 mmol), PMMA (104.8 mg, 0.023 mmol), and PMDETA (2.0 mg, 0.012 mmol) into a 2 mL ampoule, and then add 0.5 mL of DMAC as the reaction solvent.

[0081] (2) Place the ampoule containing the solution under visible light to carry out the polymerization reaction.

[0082] (3) After the reaction has proceeded for 5.5 h, the tube is opened and an appropriate amount of tetrahydrofuran (THF) is added to dilute the polymerization solution. The diluted polymerization solution is then dropped into 30 mL of anhydrous methanol to precipitate, and the precipitate is filtered. The resulting polymer is dried in a vacuum drying oven until constant weight is achieved.

[0083] See Figure 3 As shown, Figure 3 The graph shows the GPC effluent curves before and after PMMA chain extension. Figure 3 As can be seen, the polymerized PMMA still retains its activity.

[0084] Test Example 5

[0085] The ultraviolet-visible light test includes the following steps:

[0086] CP-I (9.1 mg, 0.047 mmol), PMDETA (4.1 mg, 0.023 mmol), and DMAC solvent were placed in a cuvette, and the mixture was spectrally scanned at 200–800 nm. The mixture was then irradiated with light for 1 h, and the spectral scan was performed again.

[0087] See Figure 4 As shown, Figure 4 For the predicted mechanism diagram, from Figure 4 It can be a controlled free radical polymerization in which oxygen is consumed by tertiary amines.

[0088] The above descriptions are only the preferred embodiments of the present application, not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall fall within the scope of the present application.

Claims

1. A completely oxygen-resistant, reversible complexation-mediated polymerization method, characterized in that, Includes the following steps: Under completely open conditions, the polymerizable monomer, alkyl iodide, and tertiary amine are dissolved in an organic solvent, and the resulting mixed solution is placed in a constant-temperature water bath and subjected to polymerization under visible light. The molar ratio of the alkyl iodide to the tertiary amine is 1:

1. During the polymerization reaction, under visible light stimulation, the alkyl iodide acts as an initiator and is in an excited state. The tertiary amine loses an electron, and oxygen gains an electron to become a superoxide radical, which is then quenched. The alkyl iodide then initiates the polymerization of the polymerizable monomer, thereby achieving fully oxygen-resistant photo-switched controllable radical polymerization.

2. The fully oxygen-resistant, reversible complexation-mediated polymerization method according to claim 1, characterized in that, The monomer used for polymerization is methyl methacrylate.

3. The fully oxygen-resistant, reversible complexation-mediated polymerization method according to claim 1, characterized in that, The alkyl iodide was obtained directly from procurement and used a reversible complexation-mediated polymerization initiator, including 2-iodo-2-methylpropionitrile.

4. The fully oxygen-resistant, reversible complexation-mediated polymerization method according to claim 1, characterized in that, The alkyl iodide is obtained by nucleophilic substitution of bromo-iodide with alkyl bromide and iodide salt, wherein the alkyl bromide is used as the bromo-iodide transfer initiator, and methyl α-bromophenylacetate or ethyl α-bromophenylacetate is used, and the iodide salt is used as sodium iodide or tetrabutylammonium iodide.

5. The fully oxygen-resistant, reversible complexation-mediated polymerization method according to claim 1, characterized in that, The tertiary amine is one of pentamethyldiethylenetriamine, (tris[2-(dimethylamino)ethyl]amine) or tetramethylethylenediamine.

6. The fully oxygen-resistant, reversible complexation-mediated polymerization method according to claim 1, characterized in that, The organic solvent is one of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, or tetrahydrofuran.

7. The fully oxygen-resistant, reversible complexation-mediated polymerization method according to claim 1, characterized in that, The temperature of the constant temperature water bath during the polymerization reaction is 25℃, and the reaction time is 5-24h.

8. The fully oxygen-resistant, reversible complexation-mediated polymerization method according to claim 1, characterized in that, The polymerization reaction is carried out in a fully open ampoule.

9. The fully oxygen-resistant, reversible complexation-mediated polymerization method according to claim 1, characterized in that, The visible light is 12W, 4mW / cm². 2 LED lights.

10. The fully oxygen-resistant, reversible complexation-mediated polymerization method according to claim 1, characterized in that, The molecular weight distribution of the polymer obtained by the polymerization reaction is <1.42.

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