CN102391413A - Side chain functional polymer and preparation method thereof - Google Patents

Abstract

The invention discloses a side chain functionalized polymer and a preparation method thereof. The polymerization system is composed of a monomer, an initiator, a chain transfer agent, a catalyst, a complexing agent and a coupling component. The monomer is methacrylic acid Nidecyl undecyl ester, the catalyst is copper; the complexing agent is N, N, N', N", N"-pentamethyldiethylenetriamine, and the coupling component is 4-methoxy Base-4'-propynyloxyazobenzene; free radicals are generated by single electron transfer, and chain growth is carried out in the form of reversible addition and fragmentation chain transfer. Copper catalyzed cycloaddition reaction between azide group and alkyne group in the coupling component to obtain side chain functionalized polymer. Since the present invention combines the SET-RAFT method and the click chemistry method, only one step reaction is required to obtain the polymer with side chain functionalization, thus reducing the reaction steps, reducing the waste rate of raw materials, realizing the rational utilization of resources, and basically There is no side reaction, and there is no need for troublesome purification operations.

Description

A kind of side chain functionalized polymer and preparation method thereof

technical field

The present invention relates to a simple and controllable preparation method of a side chain functionalized polymer, in particular to a method for generating free radicals induced by single electron transfer and carrying out chain growth (SET-RAFT) polymerization in the form of reversible addition-fragmentation chain transfer Simultaneously performing click chemistry reactions allows for a controlled approach to the preparation of polymers.

Background technique

Click Chemistry (Click Chemistry) is a class of chemical reactions proposed by Professor K.Barry Sharpless in 2001, which has the characteristics of high efficiency, high selectivity, high adaptability to solvents and functional groups, and mild reaction conditions. A widely used class of click chemistry techniques is the copper-catalyzed cycloaddition of azides and alkynes (CuAAC). In terms of polymer chemistry, a series of functional polymer materials, including dendrimers, hydrogels, drugs and functionalized polymers, can be conveniently synthesized by using CuAAC combined with "living" controllable free radical polymerization method. Therefore, the introduction of azide or alkynyl groups into polymers is the key to the simple synthesis of polymer chemical materials using click chemistry. So far, there are mainly three methods for introducing azide or alkynyl groups: (1) introducing azide or alkynyl groups through post-modification of polymers; (2) using azide or alkynyl-containing initiators or chains transfer agent, thereby introducing azide or alkynyl groups at the end of the polymer; (3) direct polymerization of monomers containing azide or alkynyl groups to achieve the introduction of azide or alkynyl groups at the side chain of the polymer . Compared with the first two methods, the direct polymerization of azide or alkyne-containing monomers can obtain a high functional group density in the polymer side chain, and then a series of groups with special properties can be introduced into the side chain through CuAAC reaction. groups to synthesize a variety of functional comb polymers.

By directly polymerizing azide-containing monomers, the obtained polymerization results must be "active" and controllable, while ensuring the integrity of the azide group, which is very sensitive to ultraviolet light and temperature , the risk of explosion is prone to occur at high temperatures, so the successful controllable polymerization of azide-containing monomers is not easy, and there are relatively few literature reports on this aspect. There are:

(1) Initiate polymerization of azide-containing monomers at 0°C under ⁶⁰ Coγ irradiation (see: (a) DBHua, RKBai, CYPan. A Strategy for Synthesis of Azide Polymers via Controlled/Living Free Radical Copolymerization of Allyl Azide under ⁶⁰ Coγ-rayIrradiation.Chem.Mater.2005, 17, 4574-4576.(b)DBHua, RKBai, CYPan.A Strategy for Developing Novel Structural Polyurethanes and Functional Materials.Controlled/Living Free-Radical Polymerization of Acryloyl Azide under ⁶⁰ Coγ- rayIrradiation.Macromolecules 2005, 38, 3051-3053.(c)HTZheng, RKBai, CYPan.Controlled/Living Free-Radical Copolymerization of 4-(Azidocarbonyl)Phenyl Methacrylate with Methyl Acrylate under ⁶⁰ Coγ-Ray Irradiation.J.Polym.Sci .: Part A: Polym. Chem. 2007, 45, 2609-2616.). This method uses low temperature technology to realize the controllable polymerization of azide monomers, and tries to synthesize side chain functionalized polymers by using the obtained polymers through CuAAC reaction. However, a two-step method is required, the synthesis steps are complicated, and the polymer needs to be separated and purified in multiple steps.

(2) Reversible addition-fragmentation chain transfer (RAFT) polymerization of azide-containing monomers near room temperature (see:

(a) Y.Li, Benicewicz. Well-Controlled Polymerization of 2-AzidoethyMethacrylate at Near Room Temperature and Click Functionalization. J.Polym.Sci.: Part A: Polym.Chem.2007, 45, 4300-4308; (b) G. Li, H.T. Zheng, R.K. Bai. AFacile Strategy for the Preparation of Azide Polymers via Room Temperature RAF Polymerization by Redox Initiation. Macromol. Rapid. Commun. 2009, 30, 442-447). This method adopts another kind of initiation method at room temperature to realize the room temperature controllable polymerization of azide monomer on the other hand, but there are also complicated synthesis steps in the synthesis of side chain functionalized polymers, and the polymers need to go through multiple steps. The problem of separation and purification.

(4) Atom Transfer Radical Polymerization (ATRP) at 50°C (see: B.S.Sumerlin, K.Matyjaszewski.Highly Efficient "Click" Functionalization of Poly(3-azidopropyl methacrylate) Prepared by ATRP.Macromolecules 2005, 38, 7540 -7545.). This technology realizes the ATRP polymerization of azide monomer, but in the late stage of polymerization (when the monomer conversion rate is high, the polymerization is out of control, and the molecular weight distribution index of the polymer is greater than 1.5), and it needs to be synthesized by CuAAC reaction to synthesize side chain functionalized polymer. Two-step method, the synthesis steps are complicated, and the polymer needs to be separated and purified in multiple steps.

Therefore, it is necessary to study a method that can simultaneously polymerize azide-containing monomers and graft polymer side chains, so that side chain functionalized polymers can be synthesized in a one-step/one-pot process.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a variety of functional comb polymers to synthesize side chain functionalized polymers in one step/one pot at low temperature.

In order to achieve the above-mentioned purpose, the main principle of the present invention is: use the SET-RAFT polymerization method to realize the "active" controllable polymerization of azide-containing monomers, because the added catalyst zero-valent copper can be oxidized in the SET-RAFT system Thereby monovalent copper is obtained in situ, and monovalent copper can promote the generation of CuAAC reaction as the catalyzer of CuAAC reaction again, so can be by adding the coupling component (another component of CuAAC reaction of CuAAC reaction) containing azide monomer and containing alkyne group ) to achieve one-step/one-pot synthesis of side chain functionalized polymers in the SET-RAFT system.

Specifically, the present invention provides a one-step/one-pot method for the preparation of side chain functionalized polymers:

The polymerization system is composed of a monomer, an initiator, a chain transfer agent, a catalyst, a complexing agent and a coupling component, the monomer is undecyl methacrylate, and the catalyst is copper (0); the complex The position agent is N, N, N', N", N"-pentamethyldiethylenetriamine (PMDETA), and the coupling component is 4-methoxy-4'-propynyloxy azo benzene;

Single electron transfer is used to initiate the generation of free radicals, and the method of chain growth by reversible addition and fragmentation chain transfer (SET-RAFT) is used to carry out the polymerization reaction of monomers, and at the same time, Click Chemistry (Click Chemistry) reaction is carried out, and monovalent copper catalyzes azide group and the alkynyl group in the coupling component undergo a cycloaddition reaction to obtain a side chain functionalized polymer.

In the above technical scheme, the initiator is ethyl 2-bromoisobutyrate (EBiB), and the chain transfer agent is isobutyronitrile dithionaphthoate (CPDN).

In the above technical scheme, the degree of side chain grafting of the final product can be adjusted by adjusting the molar ratio of monomers and coupling components; preferably, the molar ratio of occasional components and monomers is N, 1.1≥N>0.

In the above technical scheme, the amount of initiator, chain transfer agent, catalyst, and complexing agent is within the conventional numerical range, and can refer to the amount used in the conventional SET-RAFT reaction; preferably, monomer, initiator, chain transfer agent, catalyst The molar ratio to the complexing agent is 100:1:3:3:3.

In the above technical solution, the reaction is carried out in a solvent, and the solvent is dimethylsulfoxide or N,N-dimethylformamide. Preferably, the volume ratio of the monomer to the solvent is 1:6-12.

In the above technical solution, the temperature of the polymerization reaction is 0-25° C., and the atmosphere of the polymerization reaction is an oxygen-free environment.

Specifically, the preparation method of the above-mentioned one-step/one-pot synthesis of side chain functionalized polymers includes the following steps: a polymerization system is composed of monomers, initiators, chain transfer agents, catalysts, complexing agents and coupling components, and the polymerization The system is dissolved in a solvent, and reacted for 1 to 10 hours at a temperature of 0 to 25°C in an oxygen-free environment to prepare a side chain functionalized polymer; the general structural formula of the side chain functionalized polymer is :

In the formula, m≥0, n>0, and the molecular weight of the side chain functionalized polymer is 3000-45000 g/mol.

In the above technical solution, the degree of polymerization of the monomer can be controlled by adjusting the reaction time.

In the above technical solution, the solvent is dimethyl sulfoxide or N,N-dimethylformamide, and the volume ratio of the solvent to the monomer is 1:6-12.

In the above technical scheme, the synthesis method of the monomer undecyl methacrylate is as follows: 11-bromoundecyl alcohol and sodium azide are reacted by nucleophilic substitution to form 11-undecyl azide, and then Then, 11-undecyl azide alcohol and methacryloyl chloride are connected according to the ester group to synthesize the required monomer undecyl azide methacrylate.

In the above technical scheme, the preparation method of the coupling reagent 4-methoxy-4'-propynyloxyazobenzene is as follows: first prepare the diazonium salt solution of p-methoxyaniline, and mix it with Phenol undergoes a coupling reaction to form 4-methoxy-4'-hydroxyazobenzene, which is then combined with propargyl bromide under alkaline conditions to form a coupling reagent 4-methoxy-4'-propynyloxyazo benzene.

Due to the use of the above-mentioned technical solutions, the present invention has the following advantages compared with the prior art:

1. Since the present invention adopts a one-step/one-pot method to prepare side-chain functionalized polymers, that is, the combination of SET-RAFT method and click chemistry method only needs one-step reaction to obtain side-chain functionalized polymers. The polymerized polymer requires more than two steps of reaction, so the present invention can reduce the reaction steps, reduce the waste rate of raw materials, realize the rational utilization of resources, and basically have no side reactions, and do not need to perform troublesome purification operations.

2. Since the present invention adopts the polymerization method of SET-RAFT, the polymerization temperature is low and can be carried out at room temperature, so that the azide group on the monomer can remain intact, avoiding the danger of explosion in the traditional method, and reducing other side effects at the same time. The probability of the reaction occurring.

3. The polymerization rate of the preparation method of the present invention is faster, and at the stage of reaching a higher monomer conversion rate (88.3%), the molecular weight distribution of the obtained polymer is still maintained at a lower level (PDI=1.19), and there is no crossover. The phenomenon of association occurs; the whole polymerization process presents the characteristics of "activity" controllable.

4. The functionalization degree of the side chain in the preparation method of the present invention can be changed by changing the distance between the azide monomer and the alkynyl-containing coupling component (4-methoxy-4'-propynyloxyazobenzene). The ratio is effectively regulated.

Description of drawings

Fig. 1 is a schematic flow diagram of one-step/one-pot preparation of side chain functionalized polymers in Example 1;

Fig. 2 is the NMR figure of the side chain functionalized polymer P1 and P2 obtained in Example 1;

Fig. 3 is the gel chromatographic elution curve of the side chain functionalized polymer P1 and P2 obtained in embodiment one;

Fig. 4 is the infrared spectrogram of side chain functionalized polymers P1 and P2 obtained in Example 1.

Detailed ways

Below in conjunction with embodiment and accompanying drawing, the present invention will be further described:

Chemical reagents used: methacryloyl chloride, 99%, Aldrich; 11-bromoundecanol, 98%, Acros; sodium azide, 99.5%, Aldrich; ethyl 2-bromoisobutyrate (EBiB), 98%, Acros; Zero-valent copper, 98%, Aldrich; Propylene bromide, 80% solution in toluene, Acros; N, N, N', N", N"-pentamethyldiethylenetriamine (PMDETA ) and p-methoxyaniline, 98%, China National Pharmaceutical (Group) Shanghai Chemical Reagent Company; phenol, 99.5%, China National Pharmaceutical (Group) Shanghai Chemical Reagent Company; Chemical Reagent Company; Dimethylsulfoxide, 99%, China National Pharmaceutical (Group) Shanghai Chemical Reagent Company; N, N-Dimethylformamide, 99%, China National Pharmaceutical (Group) Shanghai Chemical Reagent Company; Triethylamine, 99 %, China National Pharmaceutical (Group) Shanghai Chemical Reagent Company; neutral alumina 100-200 mesh, FCP for column chromatography, China National Pharmaceutical (Group) Shanghai Chemical Reagent Company; anhydrous magnesium sulfate, sodium nitrite, sodium hydroxide, Sodium bicarbonate and potassium iodide, analytically pure, China Pharmaceutical (Group) Shanghai Chemical Reagent Company; tetrahydrofuran (THF), dichloromethane, methanol, ethanol, n-hexane and ethyl acetate, analytically pure, Changshu Yangyuan Chemical Reagent Co., Ltd.

Test equipment and conditions:

Gel Permeation Chromatography: GPC 1515 from Waters, USA; measurement conditions: three columns HR1, HR3 and HR4 are used in series, differential detector, mobile phase is tetrahydrofuran (1mL/min), column temperature is 30°C, Calibrate with polymethyl methacrylate or polystyrene standards.

Nuclear magnetic resonance instrument: 400 MHz; measurement conditions: use _CDCl3 as solvent, tetramethylsilane as internal standard, and test temperature as room temperature.

Example 1: One-step/one-pot method to prepare side chain functionalized polymers

(1) Preparation of monomers (reference: D.Damiron, M.Desorme, R-V.Ostaci, S.A.Akhrass, T.Hamaide, E.Drockenmuller, J.Polym.Sci.Part A: Polym.Chem.2009, 47, 3803): Add 12.55g of 11-bromoundecyl alcohol, 150mL of N,N-dimethylformamide and 9.75g of sodium azide aqueous solution in the reaction flask in sequence, stir at 80°C for 24 hours, then , add 150mL of dichloromethane to the reaction flask, the solution obtained is washed three times with 150mL of water, the organic layer is collected and dried overnight with anhydrous magnesium sulfate, then filtered, and rotary evaporated to obtain the colorless intermediate 11-azide undecyl alcohol. Take 8.50g of 11-azidodecanol, 4.85g of triethylamine and 100mL of anhydrous tetrahydrofuran in a reaction flask, and use an ice-salt bath to keep the temperature of the reaction solution at 0°C, and add 5.06g of methacryloyl chloride with A small amount of anhydrous tetrahydrofuran was diluted and slowly added dropwise to the reaction flask through a constant pressure dropping funnel. The dropwise addition was completed within 20 minutes, and then the reaction mixture was reacted in an ice bath for 1 hour and at room temperature for 24 hours. Then add 100mL of water, and extract three times with 100mL of dichloromethane, collect the organic layer and add anhydrous magnesium sulfate overnight, filter, and obtain the crude product after rotary evaporation, the crude product is washed with n-hexane/ethyl acetate Column chromatography separation was carried out to obtain pure azide undecyl methacrylate monomer.

(2) The chain transfer agent CPDN was prepared according to the method described in the literature (Zhu J.; Zhu X.L.; Cheng Z.P.; Lu J.M.; Liu F., Polymer, 2002, 43, 7037-7042.); the rest of the reagents were bought from reagent companies After entering, it is used after being processed by the usual method.

(3) Preparation of coupling reagent (reference: Jian Zhu, Xiulin Zhu, E.T.Kang, K.G.Neoh, Polymer, 2007, 48, 6992-6999): 2.0g p-methoxyaniline was added to hydrochloric acid solution and placed on ice After cooling in a bath, slowly add 1.34 g of an aqueous solution of sodium nitrite dropwise through a constant-pressure dropping funnel, and react in an ice bath for half an hour after the dropwise addition to obtain a p-methoxyaniline diazonium salt solution. Another 1.68g of phenol, 0.7g of sodium hydroxide and 3.0g of sodium bicarbonate were dissolved in 100mL of water and cooled in an ice-salt bath. The diazonium salt solution was slowly added dropwise to the lye, and the reaction was continued for 3 hours after the dropwise addition, and then the solution obtained by the reaction was filtered with suction, and washed with a large amount of deionized water to obtain 4-methoxy-4'-hydroxyl Nitrobenzene intermediates. Take 1.50g of 4-methoxy-4'-hydroxyazobenzene, 0.94g of propargyl bromide, 0.31g of sodium hydroxide and a catalytic amount of potassium iodide and dissolve them in 50mL of acetone solution, and reflux at 45°C for 12 hours. The obtained reaction solution is concentrated by rotary evaporation to obtain a crude product, which can be recrystallized with absolute ethanol to obtain a pure product.

(4) One-step/one-pot method to prepare side-chain functionalized polymers: add monomer methacrylic acid azide ten Monoester, coupling agent 4-methoxy-4'-propynyloxy azobenzene, initiator EBiB, chain transfer agent CPDN, catalyst zero-valent copper, complexing agent PMDETA and solvent (dimethyl sulfoxide or N , N-dimethylformamide, its volume ratio to the monomer is 1:6 (12)). The ampoule was sealed with argon gas for 10 minutes for deoxygenation, and the sealed ampoule was placed in a water bath at 25°C for a predetermined time to react. Take out the ampoule bottle at a predetermined time point, open the seal, add an appropriate amount of tetrahydrofuran to dissolve the polymer, pass the obtained polymer solution through a neutral aluminum oxide column, and pour it into a large amount of methanol solution to precipitate the polymer. After suction filtration Dry in a vacuum drying oven at room temperature to constant weight. Weigh, calculate monomer conversion rate; The structural formula of gained product is:

Wherein, M _n(GPC) of P1 =21400 g/mol, m/n=1/1; M _n(GPC) of P2 =15120 g/mol.

The specific synthesis steps of the polymer are shown in Scheme 1.

Figure 2 is the NMR spectrum of the obtained side chain functionalized polymer. In the figure, P1 is a copolymer obtained by polymerization of monomer and coupling agent at a molar ratio of 100:50 for 8 hours, and P2 is a homopolymer obtained by polymerization of monomer and coupling agent at a molar ratio of 100:110 for 10 hours. It can be observed from the figure that the triazole ring has been formed, and the hydrogen on the polymer can be found in the NMR spectrum one by one, indicating that the side chain functionalized polymer can be successfully prepared by one-step/one-pot method. At the same time, the corresponding functionalization degree can be calculated according to the characteristic hydrogen integral value. After calculation, it is known that: (1) when the monomer and the coupling agent are in a molar ratio of 100:50, the polymer functionalization degree obtained is close to 50%; (2) when the monomer and the coupling agent are in a molar ratio of 100: 110, the degree of functionalization of the obtained polymer reaches 100%. It can be seen that the degree of side chain functionalization of the polymer can be effectively controlled by adjusting the ratio of the Click Chemistry reaction components, that is, the ratio between the azide monomer and the azobenzene coupling agent containing an alkyne group.

Simultaneously from the gel chromatography (GPC) flow-out curve of the polymer that Fig. 3 obtains, the flow-out curve of polymer of different functionalization degree is normal symmetrical distribution, simultaneously the molecular weight distribution index of polymer is maintained at a lower level (P1 : M _w /M _n = 1.30; P1: M _w /M _n = 1.19; ), proving that the reaction is activity controllable.

The different functionalization degrees of polymers are further confirmed from the infrared spectrum in Figure 4. When a:b=1:1.1, the characteristic peak (2200cm ^-1 ) of the azide group on the polymer disappears completely, and at 3000cm The characteristic peak of the triazole group appeared at the position around ^-1 , which proved that the azide group of the polymer side chain was fully functionalized. When a:b=2:1, in addition to the characteristic peak of the triazole group appearing at about 3000cm ^-1 , the characteristic peak of the azide group at about 2200cm ^-1 is still clearly visible, which shows that the polymer The azide groups of the side chains are only partially functionalized.

The following conclusions can be drawn from the above data:

(1) It is feasible to simultaneously realize CuAAC reaction during the SET-RAFT polymerization process of azide monomer, and the whole process is "active" controllable;

(2) The functionalization degree of the target polymer can be adjusted by changing the ratio between the azide component and the alkyne coupling component, thereby providing a reference for realizing the synthesis of multifunctional polymers;

(3) The whole reaction is simple and easy to operate, the operation is simple, and the side reactions are few, which fundamentally overcomes the shortcomings of complex synthesis steps and cumbersome purification of polymers in traditional methods.

According to the existing literature (Zollinger, H.Azo and Diazo Chemistry; Interscience: New York, 1961), it can be seen that the above-mentioned azobenzene polymers with different contents of side chains can be applied in fields such as photoelectric switches and information storage materials.

Claims (9)

1. the preparation method of a functional side chain fluidized polymer is characterized in that:

Constitute polymerization system by monomer, initiator, chain-transfer agent, catalyzer, coordination agent and coupling component, said monomer is methylacrylic acid nitrine 11 esters, and said catalyzer is a copper; Said coordination agent is N, N, N ', N ", " five methyl diethylentriamine, said coupling component are 4-methoxyl group-4 '-the third alkynyloxy group nitrogen benzide to N;

Adopt single electron transfer to cause and produce radical; Carry out the method for chainpropagation with the mode of RAFT and carry out monomeric polyreaction; Carry out the click chemistry reaction simultaneously; Alkynyl in monovalence copper catalysis azido group and the coupling component carries out cycloaddition reaction, obtains the polymkeric substance of functional side chainization.

2. the preparation method of functional side chain fluidized polymer according to claim 1 is characterized in that: said initiator is the 2-isobutyl ethyl bromide, and said chain-transfer agent is a dithio naphthoic acid isopropyl cyanide ester.

3. the preparation method of functional side chain fluidized polymer according to claim 1 is characterized in that: component and monomeric molar ratio are N once in a while, 1.1 >=N＞0.

4. the preparation method of functional side chain fluidized polymer according to claim 1 is characterized in that: monomer, initiator, chain-transfer agent, catalyzer and coordination agent mol ratio are 100: 1: 3: 3: 3.

5. the preparation method of functional side chain fluidized polymer according to claim 1 is characterized in that: be reflected in the solvent and carry out, said solvent is methyl-sulphoxide or N, dinethylformamide, and the volume ratio of monomer and solvent is 1: 6～12.

6. the preparation method of functional side chain fluidized polymer according to claim 1 is characterized in that: the temperature of polymerization and click chemistry reaction is 0～25 ℃.

7. the preparation method of functional side chain fluidized polymer according to claim 1 is characterized in that: the atmosphere of polyreaction is an oxygen-free environment.

8. the preparation method of functional side chain fluidized polymer according to claim 1 is characterized in that, specifically may further comprise the steps:

Constitute polymerization system by monomer, initiator, chain-transfer agent, catalyzer, coordination agent and coupling component; Polymerization system is dissolved in solvent, under oxygen-free environment, under 0～25 ℃ the temperature; React about 1～10 hour, prepare the polymkeric substance of functional side chainization;

The structural formula general formula of the polymkeric substance of said functional side chainization is:

In the formula, m >=0, n＞0, the molecular weight of said functional side chain fluidized polymer is 3000～45000g/mol; Said solvent is methyl-sulphoxide or N, dinethylformamide.

9. a functional side chain fluidized polymer is characterized in that, the structural formula of said functional side chain fluidized polymer is:

In the formula, m >=0, n＞0, the molecular weight of said functional side chain fluidized polymer is 3000～45000g/mol.

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