Completely oxygen-resistant reversible complexing mediated polymerization method

Abstract

The invention discloses a completely oxygen-resistant reversible complexing mediated polymerization method which comprises the following steps: dissolving a polymeric monomer, alkyl iodide and tertiary amine in an organic solvent under a completely open condition, putting the obtained mixed solution in a constant-temperature water bath kettle, and carrying out polymerization reaction under a visible light condition; 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 an excited state, tertiary amine loses one electron, oxygen obtains electrons, is changed into superoxide free radicals and then is quenched, and the alkyl iodide further initiates the polymerization of the polymeric monomer, so that the completely oxygen-resistant controllable room-temperature RCMP polymerization is realized. According to the method, oxygen is consumed through the alkyl iodide and the tertiary amine together, on one hand, oxygen removal operation is not needed, a completely oxygen-resistant RCMP polymerization method is developed, on the other hand, other reagents are not needed except for polymerization monomers, the alkyl iodide and the tertiary amine, metal is not needed, the tertiary amine with the low price is used, and practicability is good.

Description

Technical Field

[0001] The invention belongs to the technical field of free radical polymerization, and in particular relates to a completely oxygen-resistant reversible complex-mediated polymerization method. Background Art

[0002] Reversible deactivation radical polymerization (RDRP), including atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization, nitroxide-mediated radical polymerization (NMP), and reversible complexation-mediated polymerization (RCMP), can be successfully used to prepare a variety of polymer materials with controllable molecular weight, narrow molecular weight distribution, and diverse topological structures. However, traditional RDRP usually needs to be carried out in an oxygen-free atmosphere because oxygen (O2) is a free radical scavenger that can quickly quench propagating free radicals, resulting in a loss of control over molecular weight and molecular weight distribution. To overcome this limitation, a lot of effort has been invested in developing fully oxygen-tolerant ATRP and RAFT polymerizations, so that polymerization does not require prior deoxygenation. For example, various redox-active catalysts have been added to RDRP to remove oxygen.

[0003] Compared with ATRP and RAFT polymerization, reversible complexation-mediated polymerization (RCMP) with alkyl iodides (RI) as initiators, tertiary amines (TAs) and salts as catalysts has attracted increasing attention due to its distinct characteristics such as mild conditions, wide monomer versatility, and the absence of transition metal catalysts and odorous compounds. Although the unstable CI bond of alkyl iodides poses a challenge due to the relatively low bond dissociation energy (BDE), an in situ bromine-iodine conversion strategy has been successfully developed through the halogen exchange reaction of alkyl bromides (R-Br) with sodium iodide (NaI), resulting in excellent control over the polymerization. However, it should be noted that deoxygenation is required before polymerization in most cases, and there are few studies on fully 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 structures. In the case of oxygen-tolerant RDRP, TAs used as reducing agents or co-catalysts can consume oxygen via photoinduced electron transfer. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a completely oxygen-resistant reversible complex-mediated polymerization method, in which tertiary amine consumes oxygen and alkyl iodide generates primary free radicals, thereby successfully realizing controllable reversible complex-mediated polymerization in the absence of metal.

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

[0007] A completely oxygen-resistant reversible complexation-mediated polymerization method comprising the following steps:

[0008] Under completely open conditions, the polymerization monomer, alkyl iodide and tertiary amine are dissolved in an organic solvent, and the obtained mixed solution is placed in a constant temperature water bath, and a polymerization reaction is carried out under visible light conditions; 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 as an initiator is in an excited state, the tertiary amine loses an electron, oxygen obtains an electron to become a superoxide radical and then quenches, and the alkyl iodide then initiates the polymerization of the polymerization monomer, thereby realizing completely oxygen-resistant visible light-induced room temperature reversible complexation-mediated polymerization (RCMP), and by controlling the switch of visible light, completely oxygen-resistant optically switched reversible complexation-mediated polymerization (RCMP) can also be realized.

[0009] Furthermore, the polymerizable monomer may be methyl methacrylate (MMA).

[0010] Furthermore, 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] Furthermore, the alkyl iodide is obtained by nucleophilic substitution of bromine-iodine transfer from an alkyl bromide and an iodine salt, wherein the alkyl bromide can be used as a bromine-iodine transfer initiator, such as methyl α-bromophenylacetate (MBPA) or ethyl α-bromophenylacetate (EBPA), and the iodine salt can be sodium iodide (NaI) or tetrabutylammonium iodide (TBAI).

[0012] Furthermore, the tertiary amine may be one of pentamethyldiethylenetriamine (PMDETA), (tris[2-(dimethylamino)ethyl]amine) (Me6TREN) or tetramethylethylenediamine (TMEDA).

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

[0014] Furthermore, the temperature of the thermostatic water bath during the polymerization reaction is 25° C., and the reaction time is 5-24 hours.

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

[0016] Furthermore, the visible light can be 12W, 4mW / cm 2 LED lights.

[0017] Furthermore, the molecular weight distribution of the polymer obtained by the polymerization reaction is less than 1.42.

[0018] In general, iodine radicals tend to recombine with another radical to form an iodine molecule / solvent complex (I2 / solvent). In addition, a characteristic red-yellow color can be seen after polymerization. Spin adducts generated by superoxide radicals were found to be trapped with DMPO, indicating that in the presence of CP-I and PMDETA, oxygen can be reduced to superoxide radical anions, allowing polymerization to occur in air.

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

[0020] The polymerization method of the present invention consumes oxygen through alkyl iodide and tertiary amine together. Alkyl iodide can generate primary free radicals under the stimulation of visible light. Green and controllable RCMP is successfully developed under the regulation of tertiary amine. On the one hand, no deoxygenation operation is required, and the method can be carried out in the presence of oxygen to develop a completely oxygen-resistant RCMP polymerization method. On the other hand, no other reagents are required except for the polymerization monomer, alkyl iodide and tertiary amine, and no metal is required. The use of low-cost tertiary amine enhances the practical applicability of the system.

[0021] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. The specific implementation of the present invention is given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0023] Figure 1 This is a kinetic curve of the polymerization RCMP of light-induced MMA initiated by bromine-iodine transfer in Test Example 1 of the present invention.

[0024] Figure 2 This is a kinetic curve of the polymerization RCMP of light-induced MMA initiated by CP-I in Test Example 2 of the present invention.

[0025] Figure 3 It is the GPC elution curve diagram of PMMA before and after chain extension in Test Examples 3 and 4 of the present invention.

[0026] Figure 4 A possible mechanism diagram of the fully oxygen-resistant reversible complexation-mediated polymerization method of the present invention. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings so that the purpose, features and advantages of the invention can be more clearly understood. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solution of the present invention.

[0028] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the relevant art will recognize that the embodiments may be practiced without one or more of these specific details. In other cases, well-known devices, structures, and techniques associated with the present application may not be shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0029] Unless the context requires otherwise, throughout the specification and claims, the word "comprise" and variations such as "include" and "have" should be construed in an open, inclusive sense, ie, should be interpreted as "including, but not limited to."

[0030] References throughout the specification to "one embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of "in one embodiment" or "in an embodiment" in various places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any 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 context clearly dictates otherwise. It should be noted that the term "or" is generally employed in its sense including "and / or" unless the context clearly dictates otherwise.

[0032] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Unless otherwise specified, the reagents and materials used in the present invention are commercially available.

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

[0034] First, under completely open conditions, such as in a completely open ampoule bottle, the polymerization monomer, alkyl iodide and tertiary amine are dissolved in an organic solvent and stirred 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 may be one of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC) or tetrahydrofuran (THF).

[0037] Preferably, the polymerizable monomer may 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 can be obtained from an alkyl bromide and an iodine salt by nucleophilic substitution of bromine-iodine transfer.

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

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

[0042] The fully open ampoule containing the mixed solution is then placed in a constant temperature water bath at 25°C and exposed to visible light, such as 12W, 4mW / cm 2 The polymerization reaction was carried out for 5-24 hours under the irradiation of LED light, and the molecular weight distribution of the obtained polymer was <1.42.

[0043] During the polymerization reaction, under the stimulation of visible light, the alkyl iodide as an initiator is in an excited state, the tertiary amine loses an electron, oxygen gains an electron and becomes a superoxide radical which is then quenched, and the alkyl iodide then initiates the polymerization of the polymerization monomer, thereby achieving completely oxygen-resistant visible light-induced room temperature RCMP polymerization. At the same time, by controlling the switch of visible light, completely oxygen-resistant optical switch RCMP polymerization can also be achieved.

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

[0045] Example 1

[0046] The invention discloses a polymerization method using light-induced, pentamethyldiethylenetriamine (PMDETA), methyl α-bromophenylacetate (MBPA) and an alkyl iodide generated by sodium iodide (NaI) as an initiator, which specifically comprises the following steps:

[0047] According to the molar ratio of [MMA]0:[MBPA]0:[NaI]0:[PMDETA]0=200:1:4:1, the raw materials were taken into a 2 mL ampoule, and 0.5 mL of N,N-dimethylacetamide (DMAC) was added as the reaction solvent. Under the condition that the ampoule was completely open, the reaction mixture was irradiated with visible light (12 W, 4 mW / cm 2 ) and the reaction was continued for a specified time, and the tube was broken, the polymer solution was diluted with tetrahydrofuran, and the diluted polymer solution was dropped into 250 mL of methanol for precipitation and suction filtration. The obtained polymer was placed in a vacuum drying oven and dried until constant weight.

[0048] Example 2

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

[0050] According to the molar ratio of [MMA]0:[CP-I]0:[PMDETA]0=100:1:1, the raw materials were taken into a 2 mL ampoule bottle, and 0.5 mL of N,N-dimethylacetamide (DMAC) was added as the reaction solvent. Under the condition that the ampoule bottle was completely open, the reaction mixture was irradiated with visible light (12 W, 4 mW / cm 2 ) and the reaction was continued for a specified time, and the tube was broken, the polymer solution was diluted with tetrahydrofuran, and the diluted polymer solution was dropped into 250 mL of methanol for precipitation and suction filtration. The obtained polymer was placed in a vacuum drying oven and dried until constant weight.

[0051] Example 3

[0052] The invention discloses a polymerization method using alkyl iodide generated by photoinduction, α-bromophenylacetic acid methyl ester (MBPA) and sodium iodide (NaI) as an initiator and regulated by different tertiary amines such as (tris[2-(dimethylamino)ethyl]amine) (Me6TREN) or tetramethylethylenediamine (TMEDA), which specifically comprises the following steps:

[0053] According to the molar ratio of [MMA]0:[MBPA]0:[NaI]0:[Me6TREN / TMEDA]=200:1:4:1, the raw materials were taken into a 2 mL ampoule bottle, and 0.5 mL of N,N-dimethylacetamide (DMAC) was added as the reaction solvent. Under the condition that the ampoule bottle was completely open, the reaction mixture was irradiated with visible light (12 W, 4 mW / cm 2 ) and the reaction was continued for a specified time, and the tube was broken, the polymer solution was diluted with tetrahydrofuran, and the diluted polymer solution was dropped into 250 mL of methanol for precipitation and suction filtration. The obtained polymer was placed in a vacuum drying oven and dried until constant weight.

[0054] Example 4

[0055] The polymerization method is induced by light, tri[2-(dimethylamino)ethyl]amine (Me6TREN) or tetramethylethylenediamine (TMEDA), 2-iodo-2-methylpropionitrile (CP-I) as an initiator and regulated by different tertiary amines, and specifically comprises 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 the reaction solvent. Under the condition that the ampoule was completely open, the reaction mixture was irradiated with visible light (12 W, 4 mW / cm 2 ) and the reaction was continued for a specified time, and the tube was broken, the polymer solution was diluted with tetrahydrofuran, and the diluted polymer solution was dropped into 250 mL of methanol for precipitation and suction filtration. The obtained polymer was placed in a vacuum drying oven and dried until constant weight.

[0057] Test Example 1

[0058] Kinetic verification of polymerization reaction:

[0059] (1) Five ampoules were numbered and subjected to the same treatment as follows: 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 a 2 mL ampoule.

[0060] (2) In a 25°C constant temperature water bath, the visible light (12W, 4mW / cm 2 ) was used to control the polymerization system in real time under irradiation. The same temperature conditions were repeated in sequence through the parallel group test method to examine the polymer. The reaction time interval was 4h.

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

[0062] See also Figure 1 As shown, Figure 1 The photoinduced polymerization kinetics of MMA with oxygen-resistant RCMP of alkyl iodide provided by MBPA and NaI show that the polymer chains grow in an orderly manner with the increase of reaction time. The molecular weight distribution shows that the polymerization reaction has good controllability.

[0063] Test Example 2

[0064] Kinetic verification of polymerization reaction:

[0065] (1) Five ampoules were numbered and subjected to the same treatment as follows: 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 a 2 mL ampoule.

[0066] (2) In a 25°C constant temperature water bath, the visible light (12W, 4mW / cm 2 ) was used to control the polymerization system in real time under irradiation. The same temperature conditions were repeated in sequence through the parallel group test method to examine the polymer. The reaction time interval was 1h.

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

[0068] See also Figure 2 As shown, Figure 2 The photoinduced polymerization kinetics of MMA and oxygen-resistant RCMP initiated by CP-I show that the polymer chains grow in an orderly manner with the increase of reaction time. The molecular weight distribution shows that the polymerization reaction has good controllability.

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

[0070] Table 1

[0071]

[0072] Test Example 3

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

[0074] (1) 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) were weighed and placed in a 2 mL ampoule, and 0.5 mL of DMAC was added as the reaction solvent.

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

[0076] (3) After 5 hours of reaction, open the tube and add an appropriate amount of tetrahydrofuran (THF) to dilute the polymer solution. Drop the diluted polymer solution into 30 mL of anhydrous methanol, precipitate, and filter. Place the resulting polymer in a vacuum drying oven and dry until constant weight.

[0077] See also Figure 3 As shown, Figure 3 This is the GPC elution curve of PMMA before and after chain extension. Figure 3 It can be seen that the PMMA obtained by polymerization is still active.

[0078] Test Example 4

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

[0080] (1) MMA (234 mg, 2.34 mmol), PMMA (104.8 mg, 0.023 mmol), and PMDETA (2.0 mg, 0.012 mmol) were weighed and placed in a 2 mL ampoule, and 0.5 mL of DMAC was added as the reaction solvent.

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

[0082] (3) After 5.5 hours of reaction, open the tube and add an appropriate amount of tetrahydrofuran (THF) to dilute the polymer solution. Drop the diluted polymer solution into 30 mL of anhydrous methanol, precipitate, and filter. Place the resulting polymer in a vacuum drying oven and dry until constant weight.

[0083] See also Figure 3 As shown, Figure 3 This is the GPC elution curve of PMMA before and after chain extension. Figure 3 It can be seen that the PMMA obtained by polymerization is still active.

[0084] Test Example 5

[0085] UV-Visible light testing 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. Then, the mixture was irradiated with light for 1 h, and the spectrum was scanned again.

[0087] See also Figure 4 As shown, Figure 4 is the predicted mechanism diagram, from Figure 4 In this process, oxygen can be consumed by tertiary amines to carry out controlled free radical polymerization.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A completely oxygen-resistant reversible complex-mediated polymerization method, characterized in that: The following steps are involved: Under completely open conditions, the polymerization monomer, alkyl iodide and tertiary amine are dissolved in an organic solvent, and the obtained mixed solution is placed in a constant temperature water bath, and a polymerization reaction is carried out under visible light conditions; 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 as an initiator is in an excited state, the tertiary amine loses an electron, oxygen gains electrons and becomes a superoxide radical which is then quenched, and the alkyl iodide then initiates the polymerization of the polymerization monomer, thereby realizing completely oxygen-resistant photoswitchable controllable radical polymerization.

2. The fully oxygen-resistant reversible complex-mediated polymerization method according to claim 1, characterized in that: The polymerizable monomer is methyl methacrylate.

3. The fully oxygen-resistant reversible complex-mediated polymerization method according to claim 1, characterized in that: The alkyl iodide is directly purchased and a reversible complex-mediated polymerization initiator including 2-iodo-2-methylpropionitrile is used.

4. The fully oxygen-resistant reversible complex-mediated polymerization method according to claim 1, characterized in that: The alkyl iodide is obtained by alkyl bromide and iodide salt through nucleophilic substitution bromine-iodine transfer, wherein the alkyl bromide is used as a bromine-iodine transfer initiator, and α-bromophenylacetic acid methyl ester or α-bromophenylacetic acid ethyl ester is used, and the iodide salt is used as sodium iodide or tetrabutylammonium iodide.

5. The fully oxygen-resistant reversible complex-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 complex-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 complex-mediated polymerization method according to claim 1, characterized in that: The temperature of the thermostatic water bath during the polymerization reaction is 25° C., and the reaction time is 5-24 hours.

8. The fully oxygen-resistant reversible complex-mediated polymerization method according to claim 1, characterized in that: The polymerization was carried out in a completely open ampoule.

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

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

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