CN112778444B - A kind of method for preparing polyolefin by light-induced organic catalysis - Google Patents

Abstract

The invention discloses a method for preparing polyolefin by light-induced organic catalysis. An olefin monomer, an alkyl halogen initiator and a 5,10-diaryl-5,10-dihydrophenazine organic photocatalyst react under illumination . The invention utilizes the characteristics of visible light catalysts such as low absorption of photon energy, good solubility, stable catalyst structure, wide absorption wavelength, strong excited state reduction potential, fast catalytic polymerization reaction speed and the like, and can efficiently catalyze alkyl halogen initiators to initiate polymerization of olefin monomers, not only The problem of metal residues in the polymer is effectively avoided, and the efficient preparation of polyolefin polymers without metal residues is realized, and the polymerization reaction speed is fast, the molecular weight of the polymer is controllable and the molecular weight distribution is narrow, and the obtained polymer is used as an electrical material or biological material. It has great advantages and solves the defects of the prior art such as high light source energy, unstable catalyst structure, low catalyst catalytic activity, low polymerization initiation efficiency, and metal residues.

Description

A light-induced organocatalytic method for preparing polyolefins

technical field

The invention belongs to the field of photochemistry and polymer material synthesis, and in particular relates to a method for preparing polyolefin by light-induced organic catalysis.

Background technique

Polyolefin has the characteristics of low relative density, good chemical resistance and water resistance; good mechanical strength and electrical insulation, etc. It can be used in films, pipes, plates, various molded products, wires and cables, etc. It is also widely used in packaging, electronics, electricity, automobiles, machinery, daily sundries, etc. There are many studies on its polymerization methods, among which living radical polymerization is an important method for producing polyolefins, and atom transfer radical polymerization is one of the most widely studied living radical polymerizations. Atom transfer radical polymerization is usually carried out using a redox process mediated by metal catalysts [Cu(I), Ru(II), Fe(II)]. However, the use of metal catalysts makes the metal residues in the products inevitable, which limits the application of the prepared polyolefin polymers in electrical materials, biomaterials, etc. Therefore, the present invention provides a method for preparing polyolefins by light-induced organic catalysis to effectively solve the above technical problems.

Contents of the invention

Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for preparing polyolefins by light-induced organocatalysis for the deficiencies of the prior art.

In order to solve the above-mentioned technical problems, the present invention discloses a method for preparing polyolefins by light-induced organic catalysis, which comprises olefin monomers, alkyl halogen initiators and 5,10-diaryl-5,10-dihydrophenazines The organic photocatalyst reacts under light, and its reaction formula is shown in Figure 1.

Wherein, the reaction may be a mixed solution composed of olefin monomer, alkyl halogen initiator, 5,10-diaryl-5,10-dihydrophenazine organic photocatalyst and solvent together in the reaction device, The reaction under light can also be the olefin monomer, alkyl halogen initiator, 5,10-diaryl-5,10-dihydrophenazine organic photocatalyst and solvent alone/any combination, respectively At the same time, it is pumped into the reaction device and reacted under light.

Preferably, the reaction is to put a mixed solution composed of olefin monomer, alkyl halogen initiator, 5,10-diaryl-5,10-dihydrophenazine organic photocatalyst and solvent together in the reaction device, Respond to light.

Further preferably, first dissolve the 5,10-diaryl-5,10-dihydrophenazine organic photocatalyst in a solvent, then add the olefin monomer and the alkyl halogen initiator respectively, and then in the reaction device, Respond to light.

Wherein, the olefin monomer is a vinyl monomer, preferably methyl methacrylate, methyl acrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, trifluoroethyl methacrylate Any one or a combination of esters, trifluoroethyl acrylate, styrene and acrylonitrile, more preferably methyl methacrylate.

Wherein, the alkyl halogen initiator is ethyl 2-bromo-2-phenylacetate, ethyl 2-chloro-2-phenylacetate, methyl 2-bromoisobutyrate, methyl 2-bromopropionate Any one or several combinations of 2-bromopropionitrile, preferably ethyl 2-bromo-2-phenylacetate.

Wherein, the 5,10-diaryl-5,10-dihydrophenazine organic photocatalyst is any one or a combination of formulas PC-1 to PC-16; preferably formulas PC-1 and Any one or combination of two of PC-4;

Wherein, the solvent of the reaction is any one of dimethylsulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, 1,4-dioxane, toluene and tetrahydrofuran one or a combination of several.

Wherein, the molar ratio of the olefin monomer to the alkyl halogen initiator is 5-2000:1, preferably 20-1500:1, more preferably 50-1000:1, even more preferably 70-500:1, Even more preferably, it is 100-200:1.

Wherein, the molar ratio of the olefin monomer to the 5,10-diaryl-5,10-dihydrophenazine organic photocatalyst is 1:0.0002-0.01, preferably 1:0.0008-0.002, more preferably 1 : 0.001.

Wherein, the concentration of the olefin monomer is 7-12 mmol/mL, preferably 9.35 mmol/mL.

Wherein, the light source of illumination is a light source with a wavelength of 280-550 nm or sunlight.

Wherein, the temperature of the reaction is room temperature.

Wherein, the reaction device is a microchannel reaction device or other conventional reactors, such as glass bottles.

Preferably, the reaction device is a microchannel reaction device, that is, a microchannel reactor is used for the reaction.

Further preferably, the mixed solution composed of olefin monomer, alkyl halogen initiator, 5,10-diaryl-5,10-dihydrophenazine organic photocatalyst and solvent is pumped into the microchannel reaction device together, and react below.

Wherein, as shown in Figure 2, the microchannel reaction device includes a sampler, a microchannel reactor, a receiver and a light source.

Wherein, the sample injector, the microchannel reactor and the receiver are connected in series through pipelines; the light source is located outside the microchannel reactor, and its illumination range covers the microchannel reactor.

Preferably, the material of the microchannel reactor is quartz glass.

Wherein, the retention volume of the microchannel reactor is 1-20 mL, and the tube diameter is 0.2-2 mm.

Wherein, the flow rate of the mixed solution pumped into the microchannel reaction device is 0.02-2 mL/min.

Wherein, when the reaction device is a microchannel reaction device, the reaction time is 30 minutes to 4 hours.

Wherein, when the reaction device is other conventional reactors, the reaction time is 6-20 hours.

Beneficial effect: compared with the prior art, the present invention has the following advantages:

The present invention adopts the catalyst of visible light (5,10-diaryl-5,10-dihydrophenazine organic photocatalyst), utilizes this catalyst to absorb photons with low energy, good solubility, stable catalyst structure, wide absorption wavelength, and excited state Strong reduction potential, fast catalytic polymerization reaction, etc., efficiently catalyzing alkyl halogen initiators to initiate polymerization of olefin monomers, not only effectively avoiding the problem of metal residues in polymers, but also realizing the efficient preparation of polyolefin polymers without metal residues, and The polymerization reaction speed is fast, the molecular weight of the polymer is controllable and the molecular weight distribution is narrow, and the obtained polymer has great advantages as an electrical material or a biological material, which solves the existing problems of high light source energy, unstable catalyst structure, and catalyst catalysis. Defects such as low activity, low polymerization initiation efficiency, and metal residues.

Description of drawings

The advantages of the above and/or other aspects of the present invention will become clearer as the present invention will be further described in detail in conjunction with the accompanying drawings and specific embodiments.

Figure 1 is the reaction formula for initiators to initiate the polymerization of vinyl monomers.

Fig. 2 is the structural representation of microchannel reactor in the present invention.

Detailed ways

The experimental methods described in the following examples, unless otherwise specified, are conventional methods; the reagents and materials, unless otherwise specified, can be obtained from commercial sources.

In the following examples, the abbreviation Mn means polymer number average molecular weight, PDI means polymer molecular weight distribution, GPC means gel permeation chromatography, and HNMR means hydrogen nuclear magnetic spectrum.

Example 1:

At room temperature, PC-1 (9.35μmol) was dissolved in the solvent N,N-dimethylacetamide (1mL), and then the monomer methyl methacrylate (1mL, 9.35mmol) and the initiator 2- Bromo-2-ethyl phenylacetate (93.5 μmol) was added to the solution and stirred evenly, sucked into the syringe and pumped into the microreactor, the quartz glass tube had a dwell volume of 1.61 mL and a flow rate of 0.054 mL/min. Then place the reaction under the condition of light (420-430nm), fully react, collect the effluent, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, and then wash with excess methanol, repeating three times. Then the product was measured by GPC to obtain Mn and PDI, the monomer conversion rate of the obtained product was 98.14%, PDI=1.13, Mn=11.92kDa.

Example 2:

At room temperature, PC-1 (9.35μmol) was dissolved in the solvent N,N-dimethylacetamide (1mL), and then the monomer methyl methacrylate (1mL, 9.35mmol) and the initiator 2- Ethyl chloro-2-phenylacetate (93.5 μmol) was added to the solution and stirred evenly, sucked into the syringe and pumped into the microreactor, the dwell volume of the quartz glass tube was 1.61 mL and the flow rate was 0.054 mL/min. Then place the reaction under the condition of light (420-430nm), fully react, collect the effluent, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, and then wash with excess methanol, repeating three times. Then the product was measured by GPC to obtain Mn and PDI, the monomer conversion rate of the obtained product was 97.68%, PDI=1.26, Mn=10.05kDa.

Example 3:

At room temperature, PC-1 (9.35μmol) was dissolved in the solvent N,N-dimethylacetamide (1mL), and then the monomer methyl methacrylate (1mL, 9.35mmol) and the initiator 2- Methyl bromoisobutyrate (93.5 μmol) was added to the solution and stirred evenly, sucked into the syringe and pumped into the microreactor, the dwell volume of the quartz glass tube was 1.61 mL and the flow rate was 0.054 mL/min. Then place the reaction under the condition of light (420-430nm), fully react, collect the effluent, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, and then wash with excess methanol, repeating three times. Then the product was measured by GPC to obtain Mn and PDI, the monomer conversion rate of the obtained product was 97.50%, PDI=1.25, Mn=10.61kDa.

Example 4:

At room temperature, PC-2 (9.35μmol) was dissolved in the solvent N,N-dimethylacetamide (1mL), and then the monomer methyl methacrylate (1mL, 9.35mmol) and the initiator 2- Bromo-2-ethyl phenylacetate (93.5 μmol) was added to the solution and stirred evenly, sucked into the syringe and pumped into the microreactor, the quartz glass tube had a dwell volume of 1.61 mL and a flow rate of 0.054 mL/min. Then place the reaction under the condition of light (420-430nm), fully react, collect the effluent, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, and then wash with excess methanol, repeating three times. Then the product was measured by GPC to obtain Mn and PDI, the monomer conversion rate of the obtained product was 97.56%, PDI=1.15, Mn=13.32kDa.

Example 5:

At room temperature, PC-3 (9.35μmol) was dissolved in N,N-dimethylacetamide (1mL), and then the monomer methyl methacrylate (1mL, 9.35mmol) and the initiator 2-bromo - Ethyl 2-phenylacetate (93.5 μmol) was added to the solution and stirred evenly, sucked into the syringe and pumped into the microreactor, the retention volume of the quartz glass tube was 1.61 mL, and the flow rate was 0.054 mL/min. Then place the reaction under the condition of light (420-430nm), fully react, collect the effluent, take out the reaction, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, and then wash with excess methanol, repeat three times. Then the product was measured by GPC to obtain Mn and PDI, the monomer conversion rate of the obtained product was 97.40%, PDI=1.23, Mn=13.48kDa.

Embodiment 6:

At room temperature, PC-4 (9.35μmol) was dissolved in N,N-dimethylacetamide (1mL), and then the monomer methyl methacrylate (1mL, 9.35mmol) and the initiator 2-bromo - Ethyl 2-phenylacetate (93.5 μmol) was added to the solution and stirred evenly, sucked into the syringe and pumped into the microreactor, the retention volume of the quartz glass tube was 1.61 mL, and the flow rate was 0.027 mL/min. Then place the reaction under the condition of light (420-430nm), fully react, collect the effluent, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, and then wash with excess methanol, repeating three times. Then the product was measured by GPC to obtain Mn and PDI. The monomer conversion rate of the obtained product was 98.39%, PDI=1.17, Mn=12.642kDa.

Embodiment 7:

At room temperature, PC-1 (9.35μmol) was dissolved in N,N-dimethylacetamide (1mL), and then the monomer methyl methacrylate (1mL, 9.35mmol) and the initiator 2-bromo- Ethyl 2-phenylacetate (187 μmol) was added to the solution and stirred evenly, sucked into the syringe and pumped into the microreactor, the retention volume of the quartz glass tube was 1.61 mL, and the flow rate was 0.027 mL/min. Then place the reaction under the condition of light (420-430nm), fully react, collect the effluent, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, and then wash with excess methanol, repeating three times. Then the product was measured by GPC to obtain Mn and PDI, the monomer conversion rate of the product obtained was 97.14%, PDI=1.10, Mn=5.92kDa.

Example 8: At room temperature, PC-1 (9.35 μmol) was dissolved in N,N-dimethylacetamide (1 mL), and then the monomer methyl methacrylate (1 mL, 9.35 mmol) and the initiator Agent 2-bromo-2-ethyl phenylacetate (46.8 μmol) was added to the solution and stirred evenly, sucked into the syringe and pumped into the microreactor, the quartz glass tube had a retention volume of 1.61 mL and a flow rate of 0.027 mL/min. Then place the reaction under the condition of light (420-430nm), fully react, collect the effluent, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, and then wash with excess methanol, repeating three times. Then the product was measured by GPC to obtain Mn and PDI. The monomer conversion rate of the obtained product was 96.64%, PDI=1.21, Mn=19.27kDa.

Embodiment 9:

At room temperature, PC-1 (9.35μmol) was dissolved in N,N-dimethylacetamide (1mL), and then the monomer methyl methacrylate (1mL, 9.35mmol) and the initiator 2-bromo - Ethyl 2-phenylacetate (93.5 μmol) was added to the solution and stirred evenly, sucked into the syringe and pumped into the microreactor, the retention volume of the quartz glass tube was 1.61 mL, and the flow rate was 0.027 mL/min. Then place the reaction under the condition of light (420-430nm), fully react, collect the effluent, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, and then wash with excess methanol, repeating three times. Then the product was measured by GPC to obtain Mn and PDI, the monomer conversion rate of the obtained product was 97.13%, PDI=1.09, Mn=10.53kDa.

Example 10:

At room temperature, PC-1 (9.35μmol) was dissolved in N,N-dimethylacetamide (1mL), and then the monomer methyl methacrylate (1mL, 9.35mmol) and the initiator 2-bromo - Ethyl 2-phenylacetate (93.5 μmol) was added to the solution and stirred evenly, sucked into the syringe and pumped into the microreactor, the retention volume of the quartz glass tube was 1.61 mL, and the flow rate was 0.027 mL/min. Then put the reaction under sunlight, fully react, collect the effluent, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, and then wash with excess methanol, repeating three times. Then the product was measured by GPC to obtain Mn and PDI, the monomer conversion rate of the obtained product was 99.09%, PDI=1.23, Mn=14.21kDa.

Comparative example 1:

At room temperature, add a polytetrafluoroethylene magnetic stirrer and 5,10-dihydro-5,10-diphenylphenazine (9.35 μmol) to a 20mL transparent glass sample bottle in sequence, plug the rubber stopper and seal it, and then use The air in the bottle was removed by pumping the double row tube three times. N,N-Dimethylacetamide (1 mL), methyl methacrylate (1 mL, 9.35 mmol), ethyl 2-bromo-2-phenylacetate (93.5 μmol) were injected sequentially. Then place the reaction under the condition of light (420-430nm), react for 12 hours, take out the reaction, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, wash with excess methanol, and repeat three times. Then the product was measured by GPC to obtain Mn and PDI, the monomer conversion rate of the obtained product was 80.14%, PDI=1.31, Mn=10.92kDa. (The organic photocatalyst 5,10-dihydro-5,10-diphenylphenazine is unstable and is consumed in the system).

Comparative example 2:

At room temperature, add a polytetrafluoroethylene magnetic stirrer to a 20mL transparent glass sample bottle in turn, add Cu powder (9.35 μmol), Me ₆ -TREN ligand (9.35 μmol) and seal the rubber stopper, then use a double-row tube Vacuum three times to remove air from the bottle. Inject N,N-dimethylacetamide (1 mL), methyl methacrylate (1 mL, 9.35 mmol), ethyl 2-bromo-2-phenylacetate (93.5 μmol) in sequence, and react at 60°C for 10 h, The reaction was taken out, the HNMR was taken to measure the monomer conversion rate, the product was precipitated with methanol, and then washed with excess methanol, and repeated three times. Then use the product to measure GPC to get Mn and PDI. The monomer conversion rate of the obtained product was 91.2%, PDI=1.12, Mn=9.27kDa. (Due to the use of Cu as a catalyst, the as-prepared polymerization had metal residues).

Example 11:

At room temperature, add a polytetrafluoroethylene magnetic stirrer to a 20mL transparent glass sample bottle in turn, under nitrogen protection, fill PC-1 (9.35μmol) with a rubber stopper and seal it, then use a double-row tube to pump three times to remove Air in the bottle. N,N-Dimethylacetamide (1 mL), methyl methacrylate (1 mL, 9.35 mmol), ethyl 2-bromo-2-phenylacetate (93.5 μmol) were injected sequentially. Then place the reaction under the condition of light (420-430nm), react for 12 hours, take out the reaction, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, wash with excess methanol, and repeat three times. Then the product was measured by GPC to obtain Mn and PDI, the monomer conversion rate of the obtained product was 90.14%, PDI=1.13, Mn=11.92kDa.

Example 12

At room temperature, PC-1 (9.35μmol) was dissolved in the solvent N,N-dimethylacetamide (1mL), and then the monomer ethyl methacrylate (1.5mL, 9.35mmol) and the initiator 2 - Methyl bromoisobutyrate (93.5 μmol) was added to the solution and stirred evenly, sucked into the syringe and pumped into the microreactor, the dwell volume of the quartz glass tube was 1.61 mL and the flow rate was 0.054 mL/min. Then place the reaction under the condition of light (420-430nm), fully react, collect the effluent, take a sample to measure the monomer conversion rate by HNMR, precipitate the polymer with methanol, and then wash with excess methanol, repeating three times. Then the product was measured by GPC to obtain Mn and PDI, the monomer conversion rate of the obtained product was 97.81%, PDI=1.23, Mn=10.78kDa.

Table 1

Note: the difference between embodiment 12 and embodiment 3 in the table is that the monomers are different, embodiment 3 is methyl methacrylate; embodiment 12 is ethyl methacrylate.

The present invention provides an idea and method for a method for photo-induced organic catalysis to prepare polyolefins. There are many methods and approaches for realizing the technical solution. The above descriptions are only preferred embodiments of the present invention. Those of ordinary skill in the art can also make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. All components that are not specified in this embodiment can be realized by existing technologies.

Claims (5)

1. A method for preparing polyolefin by photoinduced organic catalysis is characterized in that an olefin monomer, an alkyl halogen initiator and a 5, 10-diaryl-5, 10-dihydrophenazine organic photocatalyst react in a microchannel reaction device under the irradiation of light;

the molar ratio of the olefin monomer to the alkyl halogen initiator is 50 to 200:1; the mol ratio of the olefin monomer to the 5, 10-diaryl-5, 10-dihydrophenazine organic photocatalyst is 1:0.001; the concentration of the olefin monomer is 7 to 12 mmol/mL;

the 5, 10-diaryl-5, 10-dihydrophenazine organic photocatalyst is any one of the formulas PC-1 to PC-4;

；

wherein the olefin monomer is any one or combination of methyl methacrylate, methyl acrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, trifluoroethyl acrylate, styrene and acrylonitrile.

2. The method according to claim 1, wherein the alkyl halogen initiator is any one or a combination of 2-bromo-2-phenylacetic acid ethyl ester, 2-chloro-2-phenylacetic acid ethyl ester, 2-bromoisobutyric acid methyl ester, 2-bromopropionic acid methyl ester and 2-bromopropionitrile.

3. The method according to claim 1, wherein the solvent for the reaction is any one or a combination of several of dimethyl sulfoxide, N-dimethylformamide, N-dimethylacetamide, 1, 4-dioxane, toluene and tetrahydrofuran.

4. The method according to claim 1, wherein the light source for illumination is a light source with a wavelength of 280 to 550 nm.

5. The method of claim 1, wherein the temperature of the reaction is room temperature.

Images