Low-molecular-weight polystyrene synthesized based on anionic chain transfer polymerization method and preparation method of low-molecular-weight polystyrene

Abstract

The invention discloses low-molecular-weight polystyrene synthesized based on an anionic chain transfer polymerization method and a preparation method thereof, and belongs to the technical field of polymer preparation. The method comprises the following steps: firstly, sequentially adding an organic monomer, an organic solvent, a polarity regulator, a chain transfer agent and an initiator into a reaction container in a water-free and oxygen-free high-purity argon gas environment, and after anionic polymerization is initiated by the initiator, carrying out gland sealing on the reaction container; the chain transfer agent is a derivative with an active metal-carbon bond; secondly, adding a terminator into the reacted polymer system to terminate the reaction; and finally, carrying out gel precipitation, filtration, washing and vacuum drying on the terminated polymer system to obtain the low-molecular-weight polymer. The low-molecular-weight polystyrene is obtained by adding the chain transfer agent containing the active metal-carbon bond structure into a polymerization system and can be applied to the fields of electronics, medical treatment and the like. Compared with the prior art, the method has the advantages that the initiator cost can be saved, the technological process can be simplified, and the method is environment-friendly and beneficial to industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer preparation. Since the polymerization rate of styrene is fast and difficult to control, and the rate curve is "S" shaped, it is difficult to control its molecular weight. Specifically, it relates to an anionic polymerization method that uses an organic chain transfer agent to effectively control the molecular weight of polystyrene. Background Art

[0002] Living polymerization refers to a polymerization reaction under appropriate synthesis conditions, without chain termination and chain transfer reactions, in which the concentration of active centers remains constant for several times longer than the time required to complete the reaction. A typical example is anionic polymerization.

[0003] In recent years, low molecular weight polymer materials have extremely high research value due to their excellent performance and wide application fields. They have attracted widespread attention from industry and academia and have become one of the hot spots in the field of polymer materials research.

[0004] In 1920, Stotinger of Germany conducted the polymerization of styrene and proposed that polystyrene is a linear polymer formed by styrene monomers connected together, thus establishing the polymer theory. In 1933, in the research on synthetic rubber in Germany, the preparation of styrene-butadiene rubber by copolymerization of butadiene and styrene was successful, and it was valued as a strategic material, which quickly promoted the industrialization of styrene. In 1934, styrene was successfully synthesized by dehydrogenation of ethylbenzene, and one year later in 1935, the industrialization of polystyrene was also successful. This opened the era of polystyrene industrialization.

[0005] With the advent of the information age, the material preparation of electronic components has become a new issue. This polymer has good electrochemical and dielectric properties and can be used in fields such as transistors and diodes. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization and a preparation method thereof. The present invention adopts living anionic polymerization, and under the action of a certain chain transfer agent, the molecular weight of polystyrene is reduced to a control range, and the amount of the chain transfer agent and the amount of the polarity regulator are changed to compare multiple aspects, and the one with the best molecular weight control effect under a certain combination is found, and unique properties are given to it to meet the application in different fields.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing low molecular weight polystyrene based on anionic chain transfer polymerization method comprises the following steps:

[0009] (1) In an anhydrous and oxygen-free high-purity argon environment, an organic monomer, an organic solvent, a polarity regulator, a chain transfer agent, and an initiator are sequentially added to a reaction vessel, and after anionic polymerization is initiated by the initiator, the reaction vessel is sealed by a gland;

[0010] The chain transfer agent is a derivative having an active metal-carbon bond, including dibutyl magnesium, benzyl magnesium bromide, and ethyl magnesium bromide;

[0011] The organic monomers include styrene, isoprene, etc.

[0012] The organic solvent includes cyclohexane, methylcyclohexane, benzene, etc.;

[0013] The polarity regulator includes tetrahydrofuran THF, tetramethylethylenediamine TMEDA, dimethoxyethane DME, diethylene glycol diethyl ether 2G, and triethylamine.

[0014] The initiator includes alkyl lithium, alkyl alkali metal or naphthalene sodium.

[0015] The anionic polymerization temperature is 25°C to 60°C and the time is 2 to 3 hours;

[0016] The mass ratio of the organic solvent to the organic monomer in the reaction system is 5 to 10:1, the amount of the initiator used is 0.305% of the mass of the organic monomer; the molar ratio of the chain transfer agent to the initiator is 1 to 3:1; when the polarity regulator is TMEDA, the equivalent ratio is 1 to 2:1; when the polarity regulator is THF, the equivalent ratio is 173 to 693:1.

[0017] (2) adding a terminator to the polymer system after the reaction to terminate the reaction; the terminator is methanol.

[0018] (3) The terminated polymer system is subjected to precipitation, filtration, washing, and vacuum drying to obtain a low molecular weight polymer.

[0019] The vacuum drying temperature is 25°C to 40°C, and the time is 18h to 48h.

[0020] The amount added was in a gradient of 1.5Li equivalent, 2Li equivalent, and 3Li equivalent for comparison.

[0021] The amount added was 173 equivalents, 277 equivalents, 555 equivalents, and 693 equivalents in a gradient for comparison.

[0022] The reaction mechanism of the present invention is: the initiator initiates the polymerization of styrene, making styrene an active species, and the added chain transfer agent quickly participates in the reaction, becomes an active species, and continues to grow. At this time, the initiating end is no longer the initiator, but the chain transfer agent or monomer styrene.

[0023] A method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization, characterized in that the molecular weight of the low molecular weight polymer is 3000-16000, M w / M n It is 1.03~1.66.

[0024] Compared with simple styrene polymerization, the present invention has the following beneficial effects:

[0025] (1) The addition of chain transfer agents, polarity regulators and initiators can produce polymers with lower molecular weight and narrower distribution, which has great research and development value.

[0026] (2) The amount of initiator used is greatly reduced, which saves costs and facilitates the subsequent removal of metal impurities at the initiation end.

[0027] (3) This method has a higher yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The GPC spectra of the polystyrene without chain transfer agent in Comparative Example 1 and the polystyrene with chain transfer agent dibutyl magnesium in Example 1 are compared.

[0029] Figure 2 The H-NMR spectra of the polystyrene without chain transfer agent in Comparative Example 1 are compared with the polystyrene with chain transfer agent dibutyl magnesium in Example 1.

[0030] Figure 3 The GPC spectra of polystyrene in Examples 6, 9 and 12 are compared with styrene as a monomer under the same THF equivalent of polarity regulator and different equivalents of dibutyl magnesium.

[0031] Figure 4 The H NMR spectra of polystyrene in Examples 6, 9 and 12 are compared with styrene as a monomer under the same THF equivalent of polarity regulator and different equivalents of dibutyl magnesium.

[0032] Figure 5 This is the MALDI-TOF MS spectrum of Example 6.

[0033] Figure 6 The GPC spectra of polystyrene in Examples 15, 18 and 21 are compared with styrene as a monomer under the same equivalent amount of dibutyl magnesium and different equivalent amounts of polarity regulator THF.

[0034] Figure 7 This is the GPC spectrum of Example 24 using styrene as a monomer and tetramethylethylenediamine TMEDA as a polarity regulator. DETAILED DESCRIPTION

[0035] The present invention provides the following examples as further explanations, but they are not intended to limit the scope of protection of the present invention. The molecular weight and molecular weight distribution index (PDI) of the polymer were analyzed by gel permeation chromatography.

[0036] Using anionic polymerization method, monomers, organic solvents, polarity regulators, chain transfer agents, and initiators are added to the system in sequence to start polymerization.

[0037] Example 1

[0038] (1) A 100 ml capped polymerization bottle was selected and placed in the transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent was added. Then 170 μL of initiator sec-butyl lithium (concentration of 1.3 mol / L) was added. The reaction was stirred at 25° C. in a sand bath for three hours.

[0039] (2) After three hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0040] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0041] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 99% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 16000 and the PDi is 1.16.

[0042] Example 2

[0043] (1) A 100 ml capped polymerization bottle was selected and placed in the transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and re-gassing. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent was added. Then 170 μL of initiator sec-butyl lithium (concentration of 1.3 mol / L) was added. The reaction was stirred at 40°C in a sand bath for two and a half hours.

[0044] (2) After the reaction was continued for two and a half hours, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn from a 2 ml syringe that had been repeatedly purged with high-purity argon gas and injected into the reaction container to terminate the reaction.

[0045] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0046] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 99% by weighing method. The molecular weight is tested by Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 15300 and the PDi is 1.14.

[0047] Example 3

[0048] (1) A 100 ml capped polymerization bottle was selected and placed in the transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent was added. Then 170 μL of initiator sec-butyl lithium (concentration of 1.3 mol / L) was added. The reaction was stirred at 60°C in a sand bath for two hours.

[0049] (2) After two hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0050] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0051] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 99% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 14500 and the PDi is 1.12.

[0052] Example 4

[0053] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 173 equivalents of THF as a polarity regulator was added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent was added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 25° C. in a sand bath for three hours.

[0054] (2) After three hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0055] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0056] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 96% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 3497 and the PDi is 1.37.

[0057] Example 5

[0058] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box, and the vacuum pump and high-purity argon gas were used for evacuation and gas replenishment. After three times of repeated operation, the bottle was brought back into the glove box, 10 g of styrene monomer was added to the polymerization bottle, 50 g of cyclohexane as solvent was added to the polymerization bottle, 173 equivalents of THF as a polarity regulator, 1.5 equivalents of dibutyl magnesium as a chain transfer agent, and 170 μL of initiator sec-butyl lithium (concentration of 1.3 mol / L) were added, and the reaction was stirred at 40° C. in a sand bath for two and a half hours.

[0059] (2) After the reaction was continued for two and a half hours, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn from a 2 ml syringe that had been repeatedly purged with high-purity argon gas and injected into the reaction container to terminate the reaction.

[0060] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0061] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 96% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 3289 and the PDi is 1.30.

[0062] Example 6

[0063] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 173 equivalents of THF as a polarity regulator was added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent was added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 60° C. in a sand bath for two hours.

[0064] (2) After two hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0065] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0066] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 96% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 3081 and the PDi is 1.25.

[0067] Example 7

[0068] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and re-gassing. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 173 equivalents of THF as a polarity regulator were added. Then 2 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 25° C. in a sand bath for three hours.

[0069] (2) After three hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0070] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0071] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 3185 and the PDi is 1.36.

[0072] Example 8

[0073] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 173 equivalents of THF as a polarity regulator were added. Then 2 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 45° C. in a sand bath for two and a half hours.

[0074] (2) After the reaction was continued for two and a half hours, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn from a 2 ml syringe that had been repeatedly purged with high-purity argon gas and injected into the reaction container to terminate the reaction.

[0075] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0076] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 3081 and the PDi is 1.34.

[0077] Example 9

[0078] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and re-gassing. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 173 equivalents of THF as a polarity regulator were added. Then 2 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 60° C. in a sand bath for two hours.

[0079] (2) After two hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0080] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0081] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 2977 and the PDi is 1.26.

[0082] Example 10

[0083] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was placed in a glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as a solvent was added to the polymerization bottle. Then 173 equivalents of THF as a polarity regulator were added. Then 3 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 25° C. in a sand bath for three hours.

[0084] (2) After three hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0085] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0086] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 2977 and the PDi is 1.31.

[0087] Embodiment 11

[0088] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as a solvent was added to the polymerization bottle. Then 173 equivalents of THF as a polarity regulator were added. Then 3 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 40° C. in a sand bath for two and a half hours.

[0089] (2) After the reaction was continued for two and a half hours, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn from a 2 ml syringe that had been repeatedly purged with high-purity argon gas and injected into the reaction container to terminate the reaction.

[0090] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0091] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 2977 and the PDi is 1.30.

[0092] Example 12

[0093] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 173 equivalents of THF as a polarity regulator were added. Then 3 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 60° C. in a sand bath for two hours.

[0094] (2) After two hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0095] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0096] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 2873 and the PDi is 1.21.

[0097] Embodiment 13

[0098] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was placed in a glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as a solvent was added to the polymerization bottle. Then 277 equivalents of THF as a polarity regulator were added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 25° C. in a sand bath for three hours.

[0099] (2) After three hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0100] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0101] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 99% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 3603 and the PDi is 1.23.

[0102] Embodiment 14

[0103] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box, and the vacuum pump and high-purity argon gas were used for evacuation and gas replenishment. After three times of repeated operation, the bottle was brought back into the glove box, 10 g of styrene monomer was added to the polymerization bottle, 50 g of cyclohexane as solvent was added to the polymerization bottle, 277 equivalents of THF as a polarity regulator, 1.5 equivalents of dibutyl magnesium as a chain transfer agent, and 170 μL of initiator sec-butyl lithium (concentration of 1.3 mol / L) were added, and the reaction was stirred at 40° C. in a sand bath for two and a half hours.

[0104] (2) After the reaction was continued for two and a half hours, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn from a 2 ml syringe that had been repeatedly purged with high-purity argon gas and injected into the reaction container to terminate the reaction.

[0105] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0106] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 99% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 3499 and the PDi is 1.20.

[0107] Embodiment 15

[0108] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 277 equivalents of THF as a polarity regulator were added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 60° C. in a sand bath for two hours.

[0109] (2) After two hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0110] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0111] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 99% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 3395 and the PDi is 1.20.

[0112] Example 16

[0113] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 555 equivalents of THF as a polarity regulator were added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 25° C. in a sand bath for three hours.

[0114] (2) After three hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0115] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0116] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 3081 and the PDi is 1.57.

[0117] Embodiment 17

[0118] (4) A 100 ml capped polymerization bottle was selected and placed in the transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and gas replenishment. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 555 equivalents of THF as a polarity regulator were added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 40° C. in a sand bath for two and a half hours.

[0119] (5) After two and a half hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0120] (6) The terminated reaction product was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the product was filtered, washed, and vacuum dried to obtain a powder product.

[0121] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 3081 and the PDi is 1.51.

[0122] Embodiment 18

[0123] (7) A 100 ml capped polymerization bottle was selected and placed in the transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and re-gassing. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 555 equivalents of THF as a polarity regulator were added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 60° C. in a sand bath for two hours.

[0124] (8) After two hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0125] (9) The terminated reaction product was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the product was filtered, washed, and vacuum dried to obtain a powder product.

[0126] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 2977 and the PDi is 1.50.

[0127] Embodiment 19

[0128] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and re-gassing. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 693 equivalents of THF as a polarity regulator were added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 25° C. in a sand bath for three hours.

[0129] (2) After three hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0130] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0131] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 2977 and the PDi is 1.66.

[0132] Embodiment 20

[0133] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. The operation was repeated three times and then the bottle was placed in a glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as a solvent was added to the polymerization bottle. Then 693 equivalents of THF as a polarity regulator were added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 40° C. in a sand bath for two and a half hours.

[0134] (2) After the reaction was continued for two and a half hours, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn from a 2 ml syringe that had been repeatedly purged with high-purity argon gas and injected into the reaction container to terminate the reaction.

[0135] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0136] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 2977 and the PDi is 1.50.

[0137] Embodiment 21

[0138] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 693 equivalents of THF as a polarity regulator were added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 60° C. in a sand bath for two hours.

[0139] (2) After two hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0140] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0141] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 2977 and the PDi is 1.41.

[0142] Embodiment 22

[0143] (1) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and refilling. The operation was repeated three times and then the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as a solvent was added to the polymerization bottle. Then 2 equivalents of TMEDA as a polarity regulator were added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 25° C. in a sand bath for three hours.

[0144] (2) After three hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0145] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0146] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 99% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 6775 and the PDi is 1.27.

[0147] Embodiment 23

[0148] (4) A 100 ml capped polymerization bottle was selected and placed in a transition chamber of a glove box. The bottle was evacuated and refilled with gas using a vacuum pump and high-purity argon gas. The operation was repeated three times and the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. 50 g of cyclohexane as a solvent was added to the polymerization bottle. 2 equivalents of TMEDA as a polarity regulator were added. 1.5 equivalents of dibutyl magnesium as a chain transfer agent were added. 170 μL of initiator sec-butyl lithium (at a concentration of 1.3 mol / L) was added. The reaction was stirred at 40° C. in a sand bath for two and a half hours.

[0149] (5) After two and a half hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0150] (6) The terminated reaction product was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the product was filtered, washed, and vacuum dried to obtain a powder product.

[0151] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 99% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 6567 and the PDi is 1.22.

[0152] Embodiment 24

[0153] (7) A 100 ml pressure-capped polymerization bottle was selected and placed in the transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and re-gassing. After repeating the operation three times, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as a solvent was added to the polymerization bottle. Then 2 equivalents of TMEDA as a polarity regulator were added. Then 1.5 equivalents of dibutyl magnesium as a chain transfer agent were added. Then 170 μL of initiator sec-butyl lithium (concentration was 1.3 mol / L) was added. The reaction was stirred at 60° C. in a sand bath for two hours.

[0154] (8) After two hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0155] (9) The terminated reaction product was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the product was filtered, washed, and vacuum dried to obtain a powder product.

[0156] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 99% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 6255 and the PDi is 1.14.

[0157] Comparative Example 1

[0158] (1) A 100 ml capped polymerization bottle was selected and placed in the transition chamber of a glove box. The vacuum pump and high-purity argon gas were used for evacuation and re-gassing. After three times of repeated operation, the bottle was brought back into the glove box. 10 g of styrene monomer was added to the polymerization bottle. Then 50 g of cyclohexane as solvent was added to the polymerization bottle. Then 170 μL of initiator sec-butyl lithium (concentration of 1.3 mol / L) was added. The reaction was stirred at 60°C in a sand bath for three hours.

[0159] (2) After three hours of reaction, the sealed container was removed from the glove box, and 2 ml of isopropanol was drawn into the reaction container using a 2 ml syringe that had been repeatedly purged with high-purity argon gas to terminate the reaction.

[0160] (3) The terminated reactant was slowly poured into a beaker containing 400 ml of anhydrous methanol for sedimentation. After stirring and standing overnight, the mixture was filtered, washed, and vacuum dried to obtain a powder product.

[0161] The monomer conversion rate of the low molecular weight polystyrene synthesized by the technology of this embodiment is 98% by weighing method. The molecular weight is tested by using Alliance 2000 gel permeation chromatography tester produced by Waters Company, and the number average molecular weight of the polymer is 69738 and the PDi is 1.03.

[0162] It can be seen from the data that before and after the addition of the chain transfer agent, the molecular weight after the addition of the chain transfer agent has been significantly reduced, but it is still about 16,000. After adding different equivalents of polarity regulators, the molecular weight has dropped to about 3,000. The more equivalents of polarity regulators are added, the better the effect of chain transfer is. It also shows that the chain transfer agent and the polarity regulator must be added at the same time to achieve better results. Under the same equivalent of polarity regulator, the more equivalents of chain transfer agent are added, the better the effect of chain transfer is. Therefore, when preparing polymers of equal molecular weight, the introduction of the chain transfer agent of the present invention can greatly save actual costs, that is, the amount of initiator used, and at the same time can obtain the same effect. It also simplifies the process flow and protects the environment.

[0163] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization, characterized in that: The following steps are involved: The first step is to sequentially add an organic monomer, an organic solvent, a polarity regulator, a chain transfer agent, and an initiator into a reaction vessel in an anhydrous and oxygen-free high-purity argon environment. After anionic polymerization is initiated by the initiator, the reaction vessel is sealed with a gland; the chain transfer agent is a derivative having an active metal-carbon bond; the temperature of the anionic polymerization is 25° C. to 60° C., and the time is 2 to 3 hours; The second step is to add a terminator to the polymer system after the reaction to terminate the reaction; The third step is to precipitate, filter, wash and vacuum dry the terminated polymer system to obtain a low molecular weight polymer.

2. A method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization according to claim 1, characterized in that: In the first step, the chain transfer agent includes dibutyl magnesium, benzyl magnesium bromide, and ethyl magnesium bromide.

3. A method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization according to claim 1, characterized in that: In the first step, the organic monomers include styrene and isoprene.

4. A method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization according to claim 1, characterized in that: The polarity regulator in the first step includes tetrahydrofuran THF, tetramethylethylenediamine TMEDA, dimethoxyethane DME, diethylene glycol diethyl ether 2G, and triethylamine; and the initiator includes alkyl lithium, alkyl alkali metal or sodium naphthalene.

5. A method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization according to claim 1, characterized in that: In the first step: the mass ratio of the organic solvent to the organic monomer in the reaction system is 5 to 10:1, the amount of the initiator is 0.305% of the mass of the organic monomer; the molar ratio of the chain transfer agent to the initiator is 1 to 3:1; when the polarity regulator is TMEDA, the equivalent ratio is 1 to 2:1; when the polarity regulator is THF, the equivalent ratio is 173 to 693:

1.

6. A method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization according to claim 1, characterized in that: In the first step: the organic solvent includes cyclohexane, methylcyclohexane and benzene.

7. A method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization according to claim 1, characterized in that: In the second step, the terminator is methanol.

8. A method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization according to claim 1, characterized in that: In the third step, the vacuum drying temperature is 25°C to 40°C and the time is 18h to 48h.

9. A method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization, characterized in that: The method is obtained by any one of claims 1 to 8.

10. The method for synthesizing low molecular weight polystyrene based on anionic chain transfer polymerization according to claim 9, characterized in that: The molecular weight of the low molecular weight polymer is 3000 to 16000. w / M n It is 1.03~1.66.

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