CN116284526A - Reactive anion chain transfer polymerization method for synthesizing low molecular weight polymer - Google Patents
Reactive anion chain transfer polymerization method for synthesizing low molecular weight polymer Download PDFInfo
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Abstract
The invention provides a living anion chain transfer polymerization method for synthesizing a low molecular weight polymer, belonging to the technical field of polymer preparation. Based on the anion polymerization theory, the invention adds the organic chain transfer agent containing active beta-hydrogen structure into the polymerization system, thereby obtaining the low molecular weight polymer with narrow molecular weight distribution, and being applicable to the fields of electronic materials, medical treatment, rubber and the like. Compared with the prior art, the preparation method provided by the invention not only can simplify the preparation process flow and optimize the reaction conditions, but also can bring convenience to subsequent treatment due to the reduction of the usage amount of the initiator, has a positive effect on environmental protection, and is beneficial to large-scale production.
Description
Technical Field
The invention belongs to the technical field of polymer preparation, and relates to an anionic polymerization method for regulating and controlling the molecular weight of olefin polymers by using an organic chain transfer reagent.
Background
Living anionic polymerization is a common ionic polymerization technology, and has been developed in the last century and widely applied to the fields of rubber, medicine, electronic materials and the like.
The living anion polymerization method for synthesizing low molecular weight polymer has been reported in many cases at home and abroad, CN107915797B discloses a preparation method of low molecular weight polybutadiene, the method is to mix an initiator and a telogen at 30-50 ℃ and obtain polybutadiene with adjustable molecular weight and structure after polymerization for 3-5 h. CN104311710a discloses a preparation method of low molecular weight polyisoprene, which comprises the steps of adding cyclohexane solvent, n-butyllithium initiator and isoprene monomer, sealing and reacting for 4-7 hours at 40-60 ℃, adding absolute ethyl alcohol to terminate, and finally vacuum drying for 10-15 hours at 60-80 ℃ to obtain pale yellow transparent polyisoprene liquid rubber. Although the above technique can obtain oligomers with higher yield, it is only suitable for the polymerization of one or a few monomers, and finding a polymerization method with universality is widely welcomed.
The present invention provides a method for preparing a low molecular weight polymer using a chain transfer agent. For living anionic polymerization, the tailoring of molecular weight follows the following rule:
wherein m is o Is the mass of the monomer, n I Is the amount of initiator species. To obtain a polymer with low molecular weight, a large amount of initiator is necessary, but the use of a large amount of initiator is disadvantageous to mass production because the initiator is expensive and the use of a large amount of initiator tends to pollute the environment and cause inconvenience to subsequent treatments. By introducing the chain transfer agent into the solution, the polymer with lower molecular weight can be obtained by using a small amount of initiator, the method not only reduces the cost, but also has mild reaction conditions and simple experimental operation, the molecular weight distribution of the obtained low molecular weight polymer is relatively narrow, Has higher commercial value.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a preparation method of a low molecular weight polymer with small initiator consumption and uniform molecular weight distribution.
In order to achieve the above object of the present invention, the following technical solutions are specifically adopted:
a living anionic chain transfer polymerization process for synthesizing a low molecular weight polymer, said living anionic polymerization process comprising the steps of:
(1) Under the anhydrous and anaerobic environment, organic solvent, initiator, chain transfer agent, polarity regulator and polymerized monomer are added into the reaction container in turn, and after the polymerization reaction is initiated, the reaction container is sealed. Wherein the chain transfer agent is a derivative with an active 2-H structure. The anionic polymerization reaction temperature is 0-60 ℃ and the time is 12-120 h. The mass ratio of the organic solvent to the polymerization monomer in the reaction system is 1-20:1, the initiator is used in an amount of 0.1-0.8% of the mass of the organic monomer, the molar ratio of the chain transfer agent to the initiator is 5-1000:1, and the molar ratio of the polarity regulator to the initiator is 1-1000:1.
(2) The polymerization reaction was terminated by adding a terminating agent after the purification treatment to the polymer system after the reaction.
(3) And (3) carrying out gum precipitation, filtration, washing and vacuum drying on the polymer system after termination to finally obtain the low molecular weight polymer.
Further, the chain transfer agent includes, but is not limited to, a series of derivatives having an active 2-H structure such as 9, 10-dihydro anthracene, 1, 4-cyclohexadiene, 1, 4-pentadiene, aminotoluene, diphenylbenzyl, triphenylbenzyl, silylmethylene, diphenylmethane, 10-hydro anthracene, 10-hydro naphthalene, etc.;
further, the anhydrous and anaerobic environment includes, but is not limited to, a glove box protected by inert gas, including, but not limited to, argon and nitrogen.
Further, the organic solvent includes, but is not limited to, benzene, cyclohexane or n-hexane; the polymeric monomers include, but are not limited to, styrene, isoprene, butadiene, p-t-butoxystyrene; such polar modifiers include, but are not limited to, tetrahydrofuran (THF), tetramethyl ethylenediamine (TMEDA), dimethoxyethane (DME), diethylene glycol diethyl ether (2G), triethylamine, and the like; such initiators include, but are not limited to, alkyl lithium (n-butyl lithium, sec-butyl lithium or tert-butyl lithium), alkyl alkali metal oxides or sodium naphthalene.
Further, the mass ratio of the organic solvent to the polymerized monomer in the reaction system is preferably 8-10:1; the initiator is used in an amount of 0.2 to 0.4 percent of the mass of the organic monomer; the molar ratio of the chain transfer agent to the initiator is preferably 20-100:1; the molar ratio of the polar regulator to the initiator is preferably 1-600:1.
Further, the anionic polymerization reaction temperature is preferably room temperature, and the time is preferably 12 to 24 hours.
Further, the terminator comprises carbon dioxide, isopropanol, deionized water and the like, and the volume ratio of the addition amount of the terminator to the addition amount of the initiator is 10-15:1.
Further, the vacuum drying temperature is 50-60 ℃ and the time is 3-6 h.
Further, the molecular weight of the low molecular weight polymer prepared by the method is 1000-5000, M ω /M n 1.01 to 1.72, wherein M ω 1500-5000, M n 1000-4000.
The reaction mechanism of the invention is as follows: the initiator initiates the monomer to carry out active anion polymerization in the organic solvent, and the added chain transfer agent with an active beta-H structure has higher activity, and the introduced polarity regulator changes the polarity of a C-Li bond and the tightness degree of an ion pair through the actions of dissociation, complexation and solvation, so that the chain transfer rate constant is far greater than the chain growth rate constant, thereby transferring the active factor on the active chain end of the polymer to the chain transfer agent, and forming a new active center to continuously initiate the polymerization of the monomer.
Compared with the prior art, the invention has the beneficial effects that:
(1) Based on the anion polymerization theory, the invention can obtain the polymer with lower molecular weight and narrower molecular weight distribution by adding the chain transfer agent, the polarity regulator and a small amount of initiator into the reaction system, and has great commercial value.
(2) And secondly, the initiator dosage used in the method is only 1-10% of that in the prior art, so that the production cost is greatly reduced, convenience is brought to the subsequent removal of metal impurities at the initiation end of the polymer, and the positive effect on environmental protection is played.
(3) In addition, the method has mild reaction conditions (can be realized under the room temperature condition), simple and convenient operation and shorter reaction time, and greatly improves the production efficiency.
Drawings
FIG. 1 is a GPC chart of the isoprene polymer PI without chain transfer agent of comparative example 1 and the isoprene polymer PI-DHA with chain transfer agent 9, 10-dihydroanthracene introduced in example 1.
FIG. 2 shows the result of comparing the chain transfer agent-free isoprene polymer PI of example 1 with the chain transfer agent-introduced 9, 10-dihydroanthracene of example 1, PI-DHA 1 HNMR spectra were compared.
FIG. 3 is a GPC chart comparing the isoprene polymer PI without chain transfer agent of comparative example 1 with the isoprene polymer PI-CHD of example 4 with chain transfer agent 1, 4-cyclohexadiene introduced.
FIG. 4 is a graph of the isoprene polymer PI without chain transfer agent of comparative example 1 and the isoprene polymer PI-CHD with chain transfer agent 1, 4-cyclohexadiene introduced in example 4 1 HNMR spectra were compared.
FIG. 5 is a GPC chart comparing the styrene polymer PS without chain transfer agent of comparative example 2 with the styrene polymer PS-AT of example 2 with chain transfer agent diphenylmethane introduced.
FIG. 6 is a graph showing the styrene polymer PS without chain transfer agent of comparative example 2 and the styrene polymer PS-AT with chain transfer agent diphenylmethane introduced in example 2 1 HNMR spectra were compared.
FIG. 7 is a comparison of GPC spectra of polyisoprene obtained in examples 17 to 21 using isoprene as a monomer and introducing different amounts of the chain transfer agent 9, 10-dihydroanthracene.
FIG. 8 shows polyisoprene obtained in examples 17 to 21 using isoprene as monomer and introducing different amounts of chain transfer agent 9, 10-dihydro anthracene 1 HNMR spectra were compared.
Detailed Description
Embodiments of the present invention will be described in detail with reference to the following examples, which are only for the purpose of illustrating the present invention and are not to be construed as limiting the scope of the present invention.
Aiming at the problems of great waste, increased cost, environmental pollution and the like caused by the preparation of low molecular weight polymers in the prior art, the invention provides a method for preparing an oligomer by utilizing a chain transfer method, which sequentially adds a solvent, a monomer, a chain transfer agent, a polarity regulator and an initiator to obtain a low molecular weight polymer with narrow molecular weight distribution, takes isoprene as a monomer, initiates anionic polymerization by using an initiator sec-butyllithium, and takes 9, 10-dihydro anthracene as a chain transfer agent, wherein the chain transfer mechanism is as follows:
Polymerization of monomer isoprene in benzene solution is initiated by initiator sec-butyllithium, and the added chain transfer agent 9, 10-dihydro anthracene has higher activity of beta-H, so that a new active center is formed to continuously initiate isoprene monomer polymerization.
Example 1
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of benzene as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.06g of 9, 10-dihydro anthracene (the mol ratio of the 9, 10-dihydro-anthracene to the initiator is 20:1) as a chain transfer agent and 0.0186g of N, N, N ', N' -tetramethyl ethylenediamine (the mol ratio of the N, N ', N' -tetramethyl ethylenediamine to the initiator is 1:1) as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of isoprene monomer to maintain the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polyisoprene.
The low molecular weight polyisoprene synthesized by the technical scheme has a monomer conversion of 99.8% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 3546g/mol, M ω /M n 1.389.
Example 2
(1) A20 mL polymerization bottle is selected, the polymerization bottle is placed in a transition cabin of a glove box to be repeatedly purged and replaced by inert gas for a plurality of times, then the polymerization bottle is moved into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), 4.0g of benzene is added as a solvent, 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L) is added into the polymerization bottle, 0.06g of 9, 10-dihydro anthracene (the mol ratio of the 9, 10-dihydro-anthracene to the initiator is 20:1) is sequentially added into the polymerization bottle as a chain transfer agent, 0.0186g of N, N, N ', N' -tetramethyl ethylenediamine (the mol ratio of the 9, N, N ', N' -tetramethyl ethylenediamine to the initiator is 1:1) is taken as a polar regulator, at this time, after stirring is carried out for 30 minutes, 0.5g of styrene monomer is added into the reaction system, the solution is kept at 4.5-5 g after the polymerization reaction system is initiated, the reaction system is changed from black into orange red by sealing the rubber bottle cap, and the reaction container is stirred at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polystyrene.
The low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion of 99.6% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 5115g/mol, M ω /M n 1.246.
Example 3
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of benzene as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.06g of 9, 10-dihydroanthracene (the mol ratio of the 9, 10-dihydroanthracene to the initiator is 20:1) as a chain transfer agent and 0.18g of tetrahydrofuran (the mol ratio of the tetrahydrofuran to the initiator is 150:1) as a polar regulator, wherein the solution is dark green, stirring for 30 minutes, adding 0.5g of styrene monomer, keeping the solution quality of a reaction system at 4.5-5 g, changing the solution from dark green into orange red after initiating polymerization, sealing the reaction container by a rubber bottle cap, and stirring the reaction under the heating condition of a sand bath at 60 ℃ for reaction.
(2) After 12 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe purged repeatedly with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polystyrene.
The low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion of 99.5% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 5751g/mol, M ω /M n 1.248.
Example 4
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of normal hexane into the polymerization bottle as a solvent, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.40g of 1, 4-cyclohexadiene (the molar ratio of the 1, 4-cyclohexadiene to the initiator is 300:1) as a chain transfer agent and 0.18g of tetrahydrofuran (the molar ratio of the 1 to the initiator is 150:1) as a polarity regulator, wherein the solution is dark green, stirring for 30 minutes, adding 0.5g of isoprene monomer, keeping the solution quality of a reaction system at 4.5-5 g, changing the solution from dark green into orange yellow after initiating polymerization, sealing the reaction container by a rubber bottle cap, and stirring the reaction under the condition of 0 ℃ for reaction.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 50 ℃ for 12h to obtain the low molecular weight polyisoprene.
The low molecular weight polyisoprene synthesized by the technical scheme has a monomer conversion of 99.6% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was found to be 3632g/mol, M ω /M n 1.302.
Example 5
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of benzene serving as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.06g of 9, 10-dihydro anthracene (the molar ratio of the 9, 10-dihydro-anthracene to the initiator is 20:1) serving as a chain transfer agent and 0.0186g of N, N, N ', N' -tetramethyl ethylenediamine (the molar ratio of the N, N ', N' -tetramethyl ethylenediamine to the initiator is 1:1) serving as a polar regulator, stirring the mixture for 30 minutes, adding 0.5g of styrene monomer, keeping the mass of a solution of a reaction system at 4.5-5 g, initiating a polymerization reaction, sealing the reaction container by using a rubber bottle cap, stirring the reaction at normal temperature.
(2) After 48 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polystyrene.
The low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion of 99.7% by a weighing method. The molecular weight was measured using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 2201g/mol, M ω /M n 1.355.
Example 6
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of benzene as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.12g of 9, 10-dihydroanthracene (the mol ratio of the 9, 10-dihydroanthracene to the initiator is 40:1) as a chain transfer agent and 0.18g of dimethoxyethane (the mol ratio of the dimethoxyethane to the initiator is 150:1) as a polar regulator, stirring the mixture for 30 minutes, adding 0.5g of isoprene monomer to maintain the solution quality of the reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating the polymerization reaction, and stirring the reaction at normal temperature.
(2) After 120 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polyisoprene.
The low molecular weight polyisoprene synthesized by the technical scheme has a monomer conversion of 99.0% by a weighing method. The molecular weight was measured using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 3875g/mol, M ω /M n 1.208.
Example 7
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of benzene serving as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.40g of 1, 4-cyclohexadiene (the mol ratio of the 1, N, N ', N ' -tetramethyl ethylenediamine (the mol ratio of the 1, N, N ' -tetramethyl ethylenediamine to the initiator is 1:1) serving as a chain transfer agent, stirring the mixture for 30 minutes, adding 0.5g of butadiene monomer, keeping the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating the polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polybutadiene.
The low molecular weight polybutadiene synthesized by the technical scheme has a monomer conversion of 99.5% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 7826g/mol, M ω /M n 1.347.
Example 8
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of benzene as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.12g of 9, 10-dihydro anthracene (the mol ratio of the 9, 10-dihydro-anthracene to the initiator is 40:1) as a chain transfer agent and 0.0186g of N, N, N ', N' -tetramethyl ethylenediamine (the mol ratio of the N, N ', N' -tetramethyl ethylenediamine to the initiator is 1:1) as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of butadiene monomer to maintain the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polybutadiene.
The low molecular weight polybutadiene synthesized by the technical scheme has a monomer conversion of 99.7% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 4264g/mol, M ω /M n 1.322.
Example 9
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of benzene as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.06g of 9, 10-dihydro anthracene (the mol ratio of the 9, 10-dihydro anthracene to the initiator is 20:1) as a chain transfer agent and 0.18g of diethylene glycol diethyl ether (the mol ratio of the diethylene glycol diethyl ether to the initiator is 150:1) as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of isoprene monomer to maintain the solution quality of the reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating the polymerization reaction, stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polyisoprene.
The low molecular weight polyisoprene synthesized by the technical scheme has a monomer conversion of 99.8% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 5798g/mol, M ω /M n 1.149.
Example 10
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of cyclohexane serving as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.06g of 9, 10-dihydroanthracene (the mol ratio of the 9, 10-dihydroanthracene to the initiator is 20:1) serving as a chain transfer agent and 0.717g of tetrahydrofuran (the mol ratio of the tetrahydrofuran to the initiator is 600:1) serving as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of p-tert-butoxystyrene monomer to maintain the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating polymerization reaction, stirring the mixture at normal temperature, and carrying out reaction.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight poly-p-tert-butoxystyrene.
The low molecular weight poly-p-tert-butoxystyrene synthesized by this embodiment gave a monomer conversion of 99.6% by weighing. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was found to be 3838g/mol, M ω /M n 1.309.
Example 11
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of benzene as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.18g of 9, 10-dihydroanthracene (the mol ratio of the 9, 10-dihydroanthracene to the initiator is 60:1) as a chain transfer agent and 0.24g of tetrahydrofuran (the mol ratio of the tetrahydrofuran to the initiator is 200:1) as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of p-tert-butoxystyrene monomer to maintain the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating polymerization reaction, stirring the mixture at normal temperature, and carrying out reaction.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight poly-p-tert-butoxystyrene.
The low molecular weight poly-p-tert-butoxystyrene synthesized by this embodiment gave a monomer conversion of 99.8% by weighing. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 2867g/mol, M ω /M n 1.265.
Example 12
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of cyclohexane serving as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.40g of 1, 4-cyclohexadiene (the mol ratio of the 1, N, N ', N ' -tetramethyl ethylenediamine (the mol ratio of the 1, N, N ' -tetramethyl ethylenediamine to the initiator is 1:1) serving as a chain transfer agent, stirring the mixture for 30 minutes, adding 0.5g of butadiene monomer, keeping the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating the polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polybutadiene.
The low molecular weight polybutadiene synthesized by the technical scheme has a monomer conversion of 99.5% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 2484g/mol, M ω /M n 1.267.
Example 13
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of cyclohexane serving as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.40g of 1, 4-cyclohexadiene (the mol ratio of the 1, 4-cyclohexadiene to the initiator is 300:1) serving as a chain transfer agent and 0.0186g of triethylamine (the mol ratio of the 1:1) serving as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of isoprene monomer, keeping the solution quality of the reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating the polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polyisoprene.
The low molecular weight polyisoprene synthesized by the technical scheme has a monomer conversion of 99.4% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 3657g/mol, M ω /M n 1.243.
Example 14
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of benzene as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.06g of 9, 10-dihydroanthracene (the mol ratio of the 9, 10-dihydroanthracene to the initiator is 20:1) as a chain transfer agent and 0.1229g of bistetrahydrofuran (the mol ratio of the dihydroanthracene to the initiator is 2:1) as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of styrene monomer to maintain the solution quality of the reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating the polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 50 ℃ for 12h to obtain the low molecular weight polystyrene.
By the present embodimentThe low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion rate of 99.8 percent by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 5632g/mol, M ω /M n 1.248.
Example 15
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of cyclohexane serving as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.80g of 1, 4-cyclohexadiene (the mol ratio of the 1, N, N ', N ' -tetramethyl ethylenediamine (the mol ratio of the 1, N, N ' -tetramethyl ethylenediamine to the initiator is 1:1) serving as a chain transfer agent, stirring the mixture for 30 minutes, adding 0.5g of styrene monomer, keeping the mass of a solution of a reaction system between 4.5 and 5g, sealing the reaction container by a rubber bottle cap after initiating polymerization reaction, and stirring the reaction container under a sand bath heating condition of 60 ℃ to perform reaction.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polystyrene.
The low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion of 99.7% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 2036g/mol, M ω /M n 1.355.
Example 16
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of cyclohexane serving as a solvent into the polymerization bottle, adding 39.56 mu L of sec-butyllithium serving as an initiator (the concentration is 0.4213 mol/L), sequentially adding 0.84g of diphenyl methane (the mol ratio of the diphenyl methane to the initiator is 300:1) serving as a chain transfer agent and 1.016g of tetrahydrofuran (the mol ratio of the diphenyl methane to the initiator is 600:1) serving as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of styrene monomer, keeping the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polystyrene.
The low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion of 99.5% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 2309g/mol, M ω /M n 1.116.
Example 17
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of cyclohexane serving as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.06g of 9, 10-dihydroanthracene (the molar ratio of the 9, 10-dihydroanthracene to the initiator is 20:1) serving as a chain transfer agent and 0.7168g of tetrahydrofuran (the molar ratio of the tetrahydrofuran to the initiator is 600:1) serving as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of isoprene monomer, keeping the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polystyrene.
The low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion of 99.5% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was found to be 3838g/mol, M ω /M n 1.709.
Example 18
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of cyclohexane serving as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.12g of 9, 10-dihydroanthracene (the mol ratio of the 9, 10-dihydroanthracene to the initiator is 40:1) serving as a chain transfer agent and 0.7168g of tetrahydrofuran (the mol ratio of the tetrahydrofuran to the initiator is 600:1) serving as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of isoprene monomer, keeping the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polystyrene.
The low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion of 9 by a weighing method9.1%. The molecular weight was measured using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 2676g/mol, M ω /M n 1.421.
Example 19
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of cyclohexane serving as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.18g of 9, 10-dihydroanthracene (the mol ratio of the 9, 10-dihydroanthracene to the initiator is 60:1) serving as a chain transfer agent and 0.7168g of tetrahydrofuran (the mol ratio of the tetrahydrofuran to the initiator is 600:1) serving as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of isoprene monomer, keeping the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polystyrene.
The low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion of 99.5% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 2410g/mol, M ω /M n 1.208.
Example 20
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of cyclohexane serving as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.24g of 9, 10-dihydroanthracene (the mol ratio of the 9, 10-dihydroanthracene to the initiator is 80:1) serving as a chain transfer agent and 0.7168g of tetrahydrofuran (the mol ratio of the tetrahydrofuran to the initiator is 600:1) serving as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of isoprene monomer, keeping the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polystyrene.
The low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion of 99.5% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 2423g/mol, M ω /M n 1.257.
Example 21
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of cyclohexane serving as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), sequentially adding 0.30g of 9, 10-dihydroanthracene (the molar ratio of the 9, 10-dihydroanthracene to the initiator is 100:1) serving as a chain transfer agent and 0.7168g of tetrahydrofuran (the molar ratio of the tetrahydrofuran to the initiator is 600:1) serving as a polarity regulator, stirring the mixture for 30 minutes, adding 0.5g of isoprene monomer, keeping the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating polymerization reaction, and stirring the reaction at normal temperature.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polystyrene.
The low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion of 99.5% by a weighing method. The molecular weight was measured using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 2133g/mol, M ω /M n 1.251.
It can be seen from FIGS. 7 and 8 that with the addition of the same polar modifier content, the molecular weight of the polymer decreases, the polydispersity decreases, and the degree of chain transfer increases as the amount of chain transfer agent 9, 10-dihydroanthracene increases.
Comparative example 1
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of benzene as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), stirring for 30 minutes, adding 0.5g of isoprene monomer, keeping the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating the polymerization reaction, stirring at normal temperature, and carrying out the reaction.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polyisoprene.
Comparative example 2
(1) Selecting a 20mL polymerization bottle, placing the polymerization bottle into a transition cabin of a glove box, repeatedly purging and replacing the polymerization bottle with inert gas for a plurality of times, transferring the polymerization bottle into the glove box (the temperature in the glove box is 25 ℃ and the pressure is 1 atm), adding 4.0g of benzene as a solvent into the polymerization bottle, adding 39.56 mu L of initiator sec-butyllithium (the concentration is 0.4213 mol/L), stirring for 30 minutes, adding 0.5g of styrene monomer, keeping the solution quality of a reaction system at 4.5-5 g, sealing the reaction container by a rubber bottle cap after initiating the polymerization reaction, stirring at normal temperature, and carrying out the reaction.
(2) After 24 hours of reaction, the closed vessel was removed from the glove box, and 0.5mL of purified isopropanol was withdrawn by a 1mL syringe repeatedly purged with an inert gas and injected into the reaction vessel to terminate the reaction.
(3) Slowly pouring the terminated reactant into a beaker containing 300mL of anhydrous methanol for sedimentation, stirring and standing for 12h, and repeatedly carrying out suction filtration and washing, and carrying out vacuum drying at 60 ℃ for 12h to obtain the low molecular weight polystyrene.
The low molecular weight polystyrene synthesized by the technical scheme has a monomer conversion of 99.8% by a weighing method. The molecular weight was measured by using an Alliance2000 type Gel Permeation Chromatography (GPC) tester manufactured by Waters corporation, and the number average molecular weight of the polymer was 28279g/mol, M ω /M n 1.046.
Styrene anionic polymerization without addition of chain transfer agent and polarity modifier was used as comparative example 1, isoprene anionic polymerization without addition of chain transfer agent and polarity modifier was used as comparative example 2, and the effects of chain transfer agent on the molecular weight and polydispersity of the polymer were examined by controlling the amounts of styrene and isoprene monomers, the amounts of initiator, the temperature, the stirring rate, etc. in the polymer products as in example 1 and example 2. It can be seen that the molecular weight of the polymer is significantly reduced by the chain transfer agent introduced in the present invention, with the same amount of initiator used; that is, in preparing polymers of equivalent molecular weight, only a smaller amount of initiator need be used under the conditions of introducing the chain transfer agent of the present invention. The method not only greatly reduces the cost and simplifies the process flow, but also plays a positive role in environmental protection.
The examples described above represent only embodiments of the invention and are not to be understood as limiting the scope of the patent of the invention, it being pointed out that several variants and modifications may be made by those skilled in the art without departing from the concept of the invention, which fall within the scope of protection of the invention.
Claims (9)
1. A living anionic chain transfer polymerization process for synthesizing a low molecular weight polymer comprising the steps of:
(1) Sequentially adding an organic solvent, an initiator, a chain transfer agent, a polarity regulator and a polymerization monomer into a reaction container in an anhydrous and anaerobic environment, and sealing the reaction container after initiating a polymerization reaction; wherein the chain transfer agent is a derivative with an active beta-H structure; the anionic polymerization reaction temperature is 0-60 ℃ and the time is 12-120 h; the mass ratio of the organic solvent to the polymerization monomer in the reaction system is 1-20:1, the initiator is used in an amount of 0.1-0.8% of the mass of the organic monomer, the molar ratio of the chain transfer agent to the initiator is 5-1000:1, and the molar ratio of the polarity regulator to the initiator is 1-1000:1;
(2) Adding a terminator into the reacted polymer system to terminate the polymerization reaction;
(3) And (3) carrying out gum precipitation, filtration, washing and vacuum drying on the polymer system after termination to obtain the low molecular weight polymer.
2. The method for living anionic chain transfer polymerization of synthetic low molecular weight polymers according to claim 1, wherein said low molecular weight polymers have a molecular weight of 1000 to 5000, M ω /M n 1.01 to 1.72, wherein M ω 1500-5000, M n 1000-4000.
3. The living anion chain transfer polymerization method for synthesizing low molecular weight polymer according to claim 1, wherein the mass ratio of the organic solvent to the polymerized monomer in the reaction system is preferably 8-10:1; the initiator is used in an amount of 0.2 to 0.4 percent of the mass of the organic monomer; the molar ratio of the chain transfer agent to the initiator is preferably 20-100:1; the molar ratio of the polar regulator to the initiator is preferably 1-600:1.
4. The living anionic chain transfer polymerization process for synthesizing low molecular weight polymers according to claim 1, wherein the anionic polymerization reaction temperature is preferably room temperature and the time is preferably 12 to 24 hours.
5. The living anionic chain transfer polymerization process for synthesizing low molecular weight polymers according to claim 1, wherein the chain transfer agent comprises, but is not limited to, 9, 10-dihydroanthracene, 1, 4-cyclohexadiene, 1, 4-pentadiene, aminotoluene, diphenylbenzyl, triphenylbenzyl, silylhydrotoluene, diphenylmethane, 10-hydroanthracene, 10-hydronaphthalene.
6. A living anionic chain transfer polymerization process for synthesizing low molecular weight polymers according to claim 1 wherein said organic solvent comprises, but is not limited to, benzene, cyclohexane or n-hexane; the polar regulator includes but is not limited to tetrahydrofuran THF, tetramethyl ethylenediamine TMEDA, dimethoxy ethane DME, diethylene glycol diethyl ether 2G, triethylamine; the initiator includes, but is not limited to, alkyl lithium, alkyl alkali metal oxide or sodium naphthalene.
7. A living anionic chain transfer polymerization process for synthesizing low molecular weight polymers according to claim 1 wherein said polymeric monomers include, but are not limited to, styrene, isoprene, butadiene, p-t-butoxystyrene.
8. The living anionic chain transfer polymerization process for synthesizing low molecular weight polymers according to claim 1, wherein said terminator comprises carbon dioxide, isopropanol, deionized water in a volume ratio of 10-15:1.
9. The living anionic chain transfer polymerization process for synthesizing low molecular weight polymers according to claim 1, wherein said vacuum drying temperature is 50 ℃ to 60 ℃ for 3 hours to 6 hours.
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