阅读说明：本技术 一种高度立构规整聚甲基丙烯酸甲酯的可控合成方法 (Controllable synthesis method of highly stereoregular polymethyl methacrylate ) 是由 沈军 孙梦尘 代枭 闵译萱 于 2020-05-20 设计创作，主要内容包括：一种高度立构规整聚甲基丙烯酸甲酯的可控合成方法,包括如下步骤：步骤一：以直链淀粉为基质原料,以3,5-二甲基苯基异氰酸酯为衍生化试剂,通过传统酯化法合成螺旋聚合物直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)；步骤二：将步骤一得到的所合成的直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)作为添加剂加入到甲基丙烯酸甲酯自由基聚合反应中,利用其规整的螺旋结构对甲基丙烯酸甲酯自由基聚合行为进行诱导,最终制备得到具有高度立构规整聚甲基丙烯酸甲酯；本发明合成路线清晰可行、工艺成熟、操作简单、需要控制的条件少而且易于实现,可用于大规模的批量生产。(A controllable synthesis method of highly stereoregular polymethyl methacrylate comprises the following steps: the method comprises the following steps: synthesizing a helical polymer amylose-tris (3, 5-dimethylphenyl carbamate) by using amylose as a matrix raw material and 3, 5-dimethylphenyl isocyanate as a derivatization reagent through a traditional esterification method; step two: adding the synthesized amylose-tris (3, 5-dimethylphenyl carbamate) obtained in the step one as an additive into methyl methacrylate free radical polymerization reaction, and inducing methyl methacrylate free radical polymerization behavior by utilizing a regular helical structure of the amylose-tris (3, 5-dimethylphenyl carbamate) to finally prepare the polymethyl methacrylate with high stereoregularity; the invention has clear and feasible synthetic route, mature process, simple operation, less condition needing to be controlled and easy realization, and can be used for large-scale batch production.)

1. A controllable synthesis method of highly stereoregular polymethyl methacrylate is characterized by comprising the following steps:

the method comprises the following steps: synthesizing a helical polymer amylose-tris (3, 5-dimethylphenyl carbamate) by using amylose as a matrix raw material and 3, 5-dimethylphenyl isocyanate as a derivatization reagent through a traditional esterification method;

step two: and (2) adding the synthesized amylose-tris (3, 5-dimethylphenyl carbamate) obtained in the step one as an additive into methyl methacrylate free radical polymerization reaction, and inducing methyl methacrylate free radical polymerization behavior by utilizing a regular helical structure of the amylose-tris (3, 5-dimethylphenyl carbamate) to finally prepare the polymethyl methacrylate with high stereoregularity.

2. The process of claim 1, wherein the first step is: taking amylose to carry out vacuum drying for 4 hours at high temperature, and then stirring and refluxing the amylose in anhydrous N, N-dimethylacetamide for 12 hours; cooling to room temperature, and adding a proper amount of lithium chloride; after stirring for 2 hours, raising the temperature again, adding anhydrous pyridine, refluxing for 6 hours, adding excessive 3, 5-dimethylphenyl isocyanate, and after reacting for 13 hours, stopping the reaction; cooling to room temperature, adding methanol, settling, filtering and washing, and vacuum drying at 60 ℃ to constant weight to obtain the helical polymer amylose-tris (3, 5-dimethylphenyl carbamate).

3. The controllable synthesis method of highly stereoregular polymethyl methacrylate according to claim 1, wherein the second step is specifically: weighing the product obtained in the step one according to 13 groups of different proportions or infiltration states set by the methyl methacrylate monomer, and drying the product in vacuum for 4 hours at normal temperature; weighing 7.73mg of azobisisobutyronitrile, dissolving in n-octane in a state of being wetted by the product obtained in the step one, and directly dissolving in methyl methacrylate by bulk polymerization; after complete dissolution, adding 0.5mL of methyl methacrylate into the n-octane solution, carrying out bulk polymerization without the step, uniformly dropwise adding the mixed solution into the solid powdery product obtained in the step I under the protection of nitrogen, and then heating to 70 ℃ for standing reaction; after 24h of reaction, stopping the reaction, cooling to room temperature, washing the product for many times by taking methanol as a settling agent, and then drying in vacuum to constant weight; and stirring and dissolving the obtained mixture in toluene at high temperature for 12h, taking the filtered supernatant, adding methanol into the supernatant for settling and washing, and performing vacuum drying at 60 ℃ to constant weight to obtain the final product polymethyl methacrylate.

Technical Field

The invention belongs to the technical field of polymer science, relates to a controllable synthesis method of methyl methacrylate, and particularly relates to a controllable synthesis method of highly stereoregular polymethyl methacrylate.

Background

Most of the polymerization or copolymerization of vinyl monomers adopts free radical polymerization, but most of the obtained polymers are random polymers due to uncontrollable reaction process, and the stereoregularity of the polymers in actual production is closely related to the quality of material performance. Currently, there are many reports on stereocontrol by using ion polymerization or coordination polymerization, but there are few studies on radical polymerization and stereocontrol behavior thereof. In addition, since vinyl esters lack conjugated substituents, propagating groups have high reactivity and low stability, chain transfer and side reactions are difficult to control, adjusting stereochemical configuration is a great challenge in synthetic polymer chemistry, and most studies are focused on how to improve isotacticity therebetween, and there are few reports on improving isotacticity of polymers.

After proper derivatization, polysaccharide high polymers such as cellulose, amylose and the like can obtain derivatives with regular structure and high-efficiency chiral recognition performance. Among them, cellulose and amylose phenyl carbamate derivatives are the most excellent in chiral recognition performance. Due to the unique main chain regular spiral structure, the polymer is widely applied to chiral recognition, asymmetric synthesis and separation and analysis of various intermediates. The influence of cellulose phenyl carbamate derivatives as an inducer on the stereoregularity of polymethyl methacrylate obtained by free radical polymerization is explored before, and the research shows that the isotacticity of the polymer is remarkably improved. Compared with cellulose derivatives, the amylose phenyl carbamate derivatives have stronger main chain flexibility, are easier to adjust the stacking arrangement of molecular chains and side groups, have higher contact probability with monomers or active chains, and are likely to obtain better induction effect.

Disclosure of Invention

The invention aims to provide a controllable synthesis method of high-degree stereoregular polymethyl methacrylate, which has simple, mature and easily-controlled whole synthesis process.

The purpose of the invention is realized by the following technical scheme:

a controllable synthesis method of highly stereoregular polymethyl methacrylate comprises the following steps:

the method comprises the following steps: synthesizing a helical polymer amylose-tris (3, 5-dimethylphenyl carbamate) by using amylose as a matrix raw material and 3, 5-dimethylphenyl isocyanate as a derivatization reagent through a traditional esterification method;

step two: and (2) adding the synthesized amylose-tris (3, 5-dimethylphenyl carbamate) obtained in the step one as an additive into methyl methacrylate free radical polymerization reaction, and inducing methyl methacrylate free radical polymerization behavior by utilizing a regular helical structure of the amylose-tris (3, 5-dimethylphenyl carbamate) to finally prepare the polymethyl methacrylate with high stereoregularity. .

The present invention may further comprise:

the first step is specifically as follows: taking amylose to carry out vacuum drying for 4 hours at high temperature, and then stirring and refluxing the amylose in anhydrous N, N-dimethylacetamide for 12 hours; cooling to room temperature, and adding a proper amount of lithium chloride; after stirring for 2 hours, raising the temperature again, adding anhydrous pyridine, refluxing for 6 hours, adding excessive 3, 5-dimethylphenyl isocyanate, and after reacting for 13 hours, stopping the reaction; cooling to room temperature, adding methanol, settling, filtering and washing, and vacuum drying at 60 ℃ to constant weight to obtain the helical polymer amylose-tris (3, 5-dimethylphenyl carbamate);

the second step is specifically as follows: weighing the product obtained in the step one according to 13 groups of different proportions or infiltration states set by the methyl methacrylate monomer, and drying the product in vacuum for 4 hours at normal temperature; weighing 7.73mg of azobisisobutyronitrile, dissolving in n-octane in a state of being wetted by the product obtained in the step one, and directly dissolving in methyl methacrylate by bulk polymerization; after complete dissolution, adding 0.5mL of methyl methacrylate into the n-octane solution, carrying out bulk polymerization without the step, uniformly dropwise adding the mixed solution into the solid powdery product obtained in the step I under the protection of nitrogen, and then heating to 70 ℃ for standing reaction; after 24h of reaction, stopping the reaction, cooling to room temperature, washing the product for many times by taking methanol as a settling agent, and then drying in vacuum to constant weight; and stirring and dissolving the obtained mixture in toluene at high temperature for 12h, taking the filtered supernatant, adding methanol into the supernatant for settling and washing, and performing vacuum drying at 60 ℃ to constant weight to obtain the final product polymethyl methacrylate.

The invention has the beneficial effects that:

in the invention, in a free radical polymerization system taking the helical polymer amylose-tris (3, 5-dimethylphenyl carbamate) as an inducer, the tacticity of the obtained polymethyl methacrylate is obviously improved, and the polymer with a more regular stereo structure is obtained. And with the increase of the feeding ratio of the amylose derivative, the isotacticity of the polymer shows a tendency of increasing, and can reach 75 percent at most, which is higher than the value reported in the literature.

The invention has clear and feasible synthetic route, mature process, simple operation, less condition needing to be controlled and easy realization, and can be used for large-scale batch production.

Drawings

FIG. 1 is a scheme for the synthesis of the amylose derivative ADMPC; wherein R is: 3, 5-dimethylphenyl, wherein R-NCO is 3, 5-dimethylphenyl isocyanate;

FIG. 2 is a radical polymerization reaction of synthesizing polymethyl methacrylate with amylose derivative ADMPC as inducer;

FIG. 3 is a NMR spectrum of amylose-tris (3, 5-dimethylphenylcarbamate) (ADMPC) ((M))¹HNMR) picture (deuterated dimethylsulfoxide, 80 ℃,500 MHz);

FIG. 4 is a nuclear magnetic resonance hydrogen spectrum of Methyl Methacrylate (MMA) and polymethyl methacrylate (PMMA) ((MMA))¹HNMR) picture (deuterated chloroform, 35 ℃,500 MHz);

FIG. 5 is the NMR spectrum of the amylose derivative ADMPC in the fully soaked state for the induced synthesis of poly (methyl methacrylate) ((M))¹H NMR) plot (deuterated chloroform, 50 ℃,500 MHz);

FIG. 6 is the NMR spectrum of the amylose derivative ADMPC in the fully soaked state for the induced synthesis of poly (methyl methacrylate) ((M))¹H NMR) chart (deuterated chloroform, 50 ℃,500MHz)

FIG. 7 shows the induction of the amylose derivative ADMPC in a semi-infiltrated stateNuclear magnetic resonance hydrogen spectrum of synthesized polymethyl methacrylate (A)¹H NMR) plot (deuterated chloroform, 50 ℃,500 MHz);

FIG. 8 is the NMR spectrum of the amylose derivative ADMPC in the semi-infiltrated state for the induced synthesis of poly (methyl methacrylate) ((M))¹H NMR) graph (deuterated chloroform, 50 ℃,500 MHz).

Detailed Description

The invention is further described below with reference to the accompanying drawings.

The amylose derivative with a regular helical structure is used as an additive to induce methyl methacrylate to generate a highly stereoregular polymer through free radical polymerization, and the influence of the amylose derivative on the stereoregularity of the polymethyl methacrylate is further researched. The invention firstly takes amylose as a substrate raw material and 3, 5-dimethylphenyl isocyanate as a derivatization reagent to synthesize the helical polymer amylose-tri (3, 5-dimethylphenyl carbamate) (ADMPC) by a traditional esterification method. On the basis, the synthesized amylose derivative is added into the methyl methacrylate free radical polymerization reaction as an additive, and the regular helical structure of the amylose derivative is utilized to induce the methyl methacrylate free radical polymerization behavior, so that the polymethyl methacrylate with higher isotacticity is finally prepared. And the nuclear magnetic resonance hydrogen spectrum is used for characterizing and analyzing the tacticity of the synthesized polymer.

The invention aims to provide a novel controllable synthesis method for preparing stereoregular polymethyl methacrylate by taking amylose-tris (3, 5-dimethylphenyl carbamate) (ADMPC) with a regular helical structure as an inducer and adding the inducer into a free radical polymerization reaction system which takes Methyl Methacrylate (MMA) as a reaction monomer, azodiisobutyronitrile as an initiator and n-octane as a small amount of reaction solvent (or no reaction solvent), and nuclear magnetic resonance hydrogen spectrum (R) ((R))¹H NMR) to quantitatively characterize and analyze the tacticity of the synthesized polymer, to obtain the tacticity of its triad.

In order to achieve the purpose, the invention adopts the technical scheme that:

1. taking amylose to carry out vacuum drying for 4 hours at high temperature, and then stirring and refluxing the amylose in anhydrous N, N-dimethylacetamide for 12 hours; cooling to room temperature, and adding a proper amount of lithium chloride; after stirring for 2 hours, raising the temperature again, adding anhydrous pyridine, refluxing for 6 hours, adding excessive 3, 5-dimethylphenyl isocyanate, and after reacting for 13 hours, stopping the reaction; cooling to room temperature, adding methanol, settling, filtering and washing, and vacuum drying at 60 deg.c to constant weight to obtain 96% yield.

2. Weighing the product obtained in the step 1) according to 13 groups of different proportions or infiltration states set by the methyl methacrylate monomer, and carrying out vacuum drying for 4h at normal temperature; then 7.73mg of azobisisobutyronitrile was weighed and dissolved in n-octane in a state of being wetted with the product obtained in 1) (bulk polymerization was directly dissolved in methyl methacrylate); after complete dissolution, adding 0.5mL of methyl methacrylate into the n-octane solution (bulk polymerization does not have the step), uniformly dropwise adding the mixed solution into the solid powdery product obtained in the step 1) under the protection of nitrogen, and then heating to 70 ℃ for standing reaction; after 24h of reaction, stopping the reaction, cooling to room temperature, washing the product for many times by taking methanol as a settling agent, and then drying in vacuum to constant weight; and stirring and dissolving the obtained mixture in toluene at high temperature for 12h, taking the filtered supernatant, adding methanol into the supernatant for settling and washing, and performing vacuum drying at 60 ℃ to constant weight to obtain the final product polymethyl methacrylate.

The amylose, the methyl methacrylate and the azodiisobutyronitrile adopted by the invention have wide sources, and the whole synthesis process is simple, mature and easy to control.

FIG. 1 shows a scheme for the synthesis of amylose-tris (3, 5-dimethylphenylcarbamate) (ADMPC). FIG. 2 shows the synthesis route of the amylose derivative ADMPC for the induced synthesis of poly (methyl methacrylate). FIG. 3 shows NMR spectra of amylose-tris (3, 5-dimethylphenylcarbamate) ((III))¹H NMR), it can be seen from the figure that the structure of the synthesized derivative is regular, and¹and (4) analyzing the integral value of each resonance peak of the H NMR spectrum, wherein the substitution degree reaches 98 percent, which shows that the substitution is basically complete, and the structure of the product meets the expected target. FIG. 4 shows NMR spectra of Methyl Methacrylate (MMA) and polymethyl methacrylate (PMMA)(¹H NMR), comparing the two figures, the successful synthesis of polymethylmethacrylate was obtained.

FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are the NMR spectra of the amylose derivative ADMPC in the fully-infiltrated and semi-infiltrated states respectively (¹H NMR), it can be seen from the figure that polymethyl methacrylate having different tacticities was synthesized by radical polymerization, and triad tacticity of the polymer was obtained according to analysis and calculation of α -methyl split peak in nuclear magnetic resonance hydrogen spectrum, polymerization results and tacticity of the obtained polymer in the fully-infiltrated and semi-infiltrated states are shown in tables 1 and 2, respectively, according to the infiltrated state.

As can be seen from tables 1 and 2, the polymerization system of all polymers is a heterogeneous system, the initiator is azobisisobutyronitrile, and the reaction solvent is a small amount of n-octane (or no reaction solvent). In this experiment, the additive ADMPC was in the form of a solid powder and the reactive monomer was uniformly dispersed in the ADMPC powder. 13 sets of experiments were set up according to the ratio of monomer to additive ADMPC and the state of impregnation, respectively 100/0 (bulk polymerization), 90/10 (bulk polymerization), 80/20 (bulk polymerization), 70/30 (full impregnation or bulk polymerization), 60/40 (full impregnation or half impregnation), 50/50 (full impregnation or half impregnation), 30/70 (full impregnation or half impregnation), 10/90 (full impregnation or half impregnation). The fully impregnated state is shown in Table 1, and the semi-impregnated state is shown in Table 2. As the content of the additive ADMPC increases, the isotacticity (mm) of the polymethyl methacrylate shows an overall increasing tendency, and the syndiotacticity (rr) shows an overall decreasing tendency but fluctuates; when the additive content reaches 90% in the fully-soaked state, the mm value of the polymer reaches a maximum of 74%, which is 67% higher than that of the polymer obtained by adding no inducer ADMPC; when the additive content reaches 90% in a semi-wetting state, the mm value of the polymer reaches a maximum value of 75% which is 68% higher than that of the polymer obtained by adding no inducer ADMPC; when the additive content is the same, the mm value increment is basically consistent under the full-infiltration state and the half-infiltration state.

From the above results, it is understood that in the radical polymerization system using the helical polymer amylose-tris (3, 5-dimethylphenylcarbamate) as an inducer, the stereoregularity of the obtained polymethyl methacrylate is significantly improved, and a polymer having a more regular stereostructure is obtained. And with the increase of the feeding ratio of the amylose derivative, the isotacticity of the polymer shows a tendency of increasing, and can reach 75 percent at most, which is higher than the value reported in the literature.

1. Taking amylose to carry out vacuum drying for 4 hours at high temperature, and then stirring and refluxing the amylose in anhydrous N, N-dimethylacetamide for 12 hours; cooling to room temperature, and adding a proper amount of lithium chloride; after stirring for 2 hours, raising the temperature again, adding anhydrous pyridine, refluxing for 6 hours, adding excessive 3, 5-dimethylphenyl isocyanate, and after reacting for 13 hours, stopping the reaction; cooling to room temperature, adding methanol, settling, filtering and washing, and vacuum drying at 60 deg.c to constant weight to obtain 96% yield.

2. Weighing the product obtained in the step 1) according to 13 groups of different proportions or infiltration states set by the methyl methacrylate monomer, and carrying out vacuum drying for 4h at normal temperature; then 7.73mg of azobisisobutyronitrile was weighed and dissolved in n-octane in a state of being wetted with the product obtained in 1) (bulk polymerization was directly dissolved in methyl methacrylate); after complete dissolution, adding 0.5mL of methyl methacrylate into the n-octane solution (the step is not required for bulk polymerization), uniformly dropwise adding the mixed solution into the solid powdery product obtained in the step 1) under the protection of nitrogen, and then heating to 70 ℃ for standing reaction; after 24h of reaction, stopping the reaction, cooling to room temperature, washing the product for many times by taking methanol as a settling agent, and then drying in vacuum to constant weight; and stirring and dissolving the obtained mixture in toluene at high temperature for 12h, taking the filtered clear liquid, adding methanol into the clear liquid for settling and washing, and drying the clear liquid in vacuum at the temperature of 60 ℃ until the weight is constant to obtain the final product polymethyl methacrylate.

3. Using nuclear magnetic resonance hydrogen spectroscopy (¹H NMR) to carry out structural characterization and performance test on the synthesized polymethyl methacrylate, and obtaining the tacticity of the synthesized polymer according to analysis and calculation of α -methyl splitting peak in the nuclear magnetic resonance hydrogen spectrum of the polymethyl methacrylate.

The polymethyl methacrylate synthesized in the free radical polymerization system taking the helical polymer amylose-tris (3, 5-dimethylphenyl carbamate) as the inducer has regular structure and higher isotacticity.

TABLE 1 tacticity results of the Induction Synthesis of polymethyl methacrylate by amylose derivative ADMPC in the fully wetted State a

Note: a. the initiator is azobisisobutyronitrile, the monomer/azobisisobutyronitrile is 100/1(mol/mol), the temperature of the free radical polymerization is 70 ℃, and the reaction time is 24 hours; b. two-unit group tacticity; c. two-unit group tacticity; d. bulk polymerization; e. the amylose derivative is in a fully-wetted state.

MMA is methyl methacrylate mono; ADMPC amylose derivative (amylose-tris (3, 5-dimethylphenylcarbamate))

TABLE 2 tacticity results of the amylose derivative ADMPC in the semi-infiltrated state for the induced synthesis of poly (methyl methacrylate)^a

Note: a. the initiator is azobisisobutyronitrile, the monomer/azobisisobutyronitrile is 100/1(mol/mol), the temperature of the free radical polymerization is 70 ℃, and the reaction time is 24 hours; b. two-unit group tacticity; c. two-unit group tacticity; d. bulk polymerization; e. the amylose derivative is in a semi-swollen state.

MMA methyl methacrylate monomer

ADMPC amylose derivative (amylose-tris (3, 5-dimethylphenylcarbamate)).