Polyisobutylene-based copolymer and preparation method thereof

Abstract

The invention belongs to the field of high-molecular compounds, and particularly relates to a thermocrosslinkable polyisobutylene block copolymer with a regular structure and a preparation method thereof. The preparation method comprises the following steps: firstly initiating polymerization of a first monomer IB through active / controllable cationic polymerization, then adding an end-capping reagent for end capping to obtain a stable PIB+ active center, and then adding a regulator to regulate the Lewis acidity and reaction activity of the system; and then adding a second monomer 4-VBCB to continue the polymerization reaction to prepare the polyisobutylene-based copolymer. The polyisobutylene-based copolymer disclosed by the invention has good mechanical properties after thermal crosslinking.

Description

Technical Field

[0001] The invention belongs to the field of polymer compounds, and in particular relates to a linear or star-shaped polyisobutylene-based block copolymer with a regular structure and capable of thermal crosslinking, and a preparation method thereof. Background Art

[0002] Isobutylene (IB) is one of the cationic polymerizable monomers, and currently polyisobutylene (PIB) can only be prepared by cationic polymerization. PIB's wide range of commercial application scenarios has been widely reported. The alternating structure of secondary carbon and quaternary carbon on its main chain gives it excellent thermal stability, chemical stability, unparalleled biocompatibility, etc. However, except for ultra-high molecular weight PIB, PIB is generally a liquid polymer with no strength. With the emergence of active cationic polymerization technology, it is possible to prepare copolymers based on PIB. Poly(styrene-b polyisobutylene-b-polystyrene) (SIBS) is such a typical copolymer. The polystyrene (PS) at both ends is a hard segment, which serves as a physical crosslinking point, and the middle PIB is a soft segment; the two phases are incompatible to form a microphase separation structure, thus having basic mechanical properties. At the same time, by adjusting the ratio of soft and hard segments, the physical properties of the copolymer can be adjusted in a wide range. Moreover, SIBS has excellent biocompatibility and has achieved great success in biomedical applications. However, the physical crosslinking structure in SIBS is limited by the glass transition temperature (Tg) of styrene, and has poor creep resistance and heat resistance.

[0003] Patent CN101918461B reports a monomer 4-vinylbenzocyclobutene (4VBCB) with a condensed ring, which can be copolymerized with IB as the second monomer and also as a cross-linking agent to form a PIB-co-4VBCB thermosetting random copolymer with two randomly distributed monomer units. The performance of the copolymer before cross-linking is similar to that of PIB, and chemical cross-linking can be directly formed by heating. The cross-linked copolymer has more excellent chemical stability, thermal stability, oxidation resistance, and creep resistance, which well compensates for the performance defects of SIBS. However, this random copolymerization method will inevitably cause various complex side reactions during the polymerization process, making the molecular weight of the final product uncontrollable, the mass content of the second monomer uncontrollable, and due to the difference in the activity of the two monomers, the copolymerization product is often low in molecular weight, low in cross-linking agent content, and low in yield, thus limiting the application of the copolymer. Summary of the invention

[0004] In order to improve the above problems, the present invention provides a thermosetting elastomer polyisobutylene-based copolymer with regular structure and a preparation method thereof. The method is active / controllable cationic polymerization, and can prepare linear diblock copolymers PIB-b-P4VBCB (polyisobutylene-b-polytetravinylphenylpropylcyclobutene), triblock copolymers P4VBCB-b-PIB-b-P4VBCB (poly-4-vinylbenzocyclobutene-b-polyisobutylene-b-polytetravinylphenylpropylcyclobutene) or star-shaped block copolymers with regular structural sequence, controllable molecular weight, controllable mass content of the second monomer, and narrow distribution. By regulating the molecular weight of the product or the ratio of structural units, a polyisobutylene-based copolymer thermosetting elastomer with various mechanical properties can be obtained. After the polyisobutylene-based copolymer thermosetting elastomer is cross-linked at high temperature, an elastomer containing a stable chemical cross-linking structure can be obtained.

[0005] The first technical problem to be solved by the present invention is to provide a method for preparing a polyisobutylene-based copolymer, comprising the following steps: firstly initiating polymerization of a first monomer IB by living / controllable cationic polymerization, then adding a capping agent to cap the first monomer to obtain a stable PIB+active center, and then adding a regulator to adjust the Lewis acidity and reaction activity of the system; then adding a second monomer 4-VBCB to continue the polymerization reaction, terminating the reaction, and obtaining the polyisobutylene-based copolymer through post-treatment.

[0006] Specifically, the preparation method of the polyisobutylene-based copolymer of the present invention comprises the following steps: a proton scavenger, a main initiator, a first part of the first monomer IB, and a co-initiator are subjected to polymerization reaction in a solvent, and then the second part of the first monomer IB is added to continue the polymerization reaction until the conversion rate of the first monomer is above 95%; then a capping agent is added to cap the end to obtain a stable PIB+ active center, and then a regulator is added to adjust the Lewis acidity and reaction activity of the system; then the second monomer 4-VBCB is added to continue the polymerization reaction, the reaction is terminated, and the polyisobutylene-based copolymer is obtained by post-treatment. Specifically, in the above preparation method, the capping agent is at least one of 1,1-diphenylethylene (DPF), 1,1-di-p-tolylethylene (DTE), 2-methylfuran, and 2-tert-butylfuran. Preferably, the capping agent is 1,1-diphenylethylene or 1,1-di-p-tolylethylene.

[0007] Specifically, in the above preparation method, the regulator is at least one of Ti(OR)4, SnBr4, SnCl4, n-Bu4NCl, BCl3, wherein R is a C1-4 alkyl. Preferably, the regulator is titanium isopropoxide (Ti(OiPr)4) or Bu4NCl.

[0008] Specifically, in the above preparation method, the main initiator is or 2-chloro-2,4,4-trimethylpentane; wherein R1 is methyl, Cl or methoxy, and R2 and R3 are each independently Cl or methoxy.

[0009] Specifically, in the above preparation method, the co-initiator is at least one of titanium tetrachloride, ferric chloride, boron trifluoride, boron trichloride, gallium trichloride, aluminum chloride, and alkylaluminum chloride. Preferably, the co-initiator is titanium tetrachloride. The alkylaluminum chloride is selected from diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, and the like.

[0010] Specifically, in the above preparation method, the proton scavenger is at least one of 2,6-di-tert-butylpyridine, 2,6-di-tert-butyl-4-methylpyridine, and 2,4,6-tri-tert-butylpyridine. Preferably, the proton scavenger is 2,6-di-tert-butylpyridine.

[0011] Specifically, in the above preparation method, the solvent is a mixed solvent of solvent A and solvent B; wherein solvent A is at least one of chloroform, dichloromethane, and chloroform, and solvent B is at least one of n-hexane, cyclohexane, and methylcyclohexane.

[0012] Furthermore, in the above preparation method, the volume ratio B / A of the mixed solvent is 7:3, 6:4, 5:5, preferably 6:4.

[0013] Furthermore, in the above preparation method, the molar ratio of the first monomer to the second monomer is (60-99):(40-1).

[0014] Furthermore, in the above preparation method, the molar ratio of the main initiator to the first monomer is 1:(50-1000).

[0015] Furthermore, in the above preparation method, the molar ratio of the main initiator to the co-initiator is 1:(2-64).

[0016] Furthermore, in the above preparation method, the molar ratio of the end-capping agent to the main initiator is 1:(1-10).

[0017] Furthermore, in the above preparation method, the molar ratio of the regulator to the end-capping agent is (1-64):1.

[0018] Furthermore, in the above preparation method, the molar ratio of the proton scavenger to the end-capping agent is 1:(1-10).

[0019] Furthermore, in the above preparation method, the second monomer is mixed with solvent B and then added into the system. Furthermore, the volume ratio of the second monomer to solvent B is 1:(1-5).

[0020] Furthermore, in the above preparation method, the first part of the first monomer accounts for 5-30wt% of the total amount of the first monomer, and the second part of the first monomer accounts for 70-95wt% of the total amount of the first monomer.

[0021] Furthermore, in the above preparation method, the mass fraction of the total mass of the first monomer and the second monomer in the reaction system is 10 to 50%.

[0022] Specifically, in the above preparation method, each reaction is carried out in an atmosphere without water or oxygen. Preferably, each reaction is carried out in an inert atmosphere.

[0023] Specifically, in the above preparation method, each reaction temperature is -50 to -100°C, preferably -80°C.

[0024] Specifically, in the above preparation method, the solvent is precooled at the reaction temperature for 5 to 20 minutes before adding the proton scavenger, the main initiator, and the first part of the first monomer. After the proton scavenger, the main initiator, and the first part of the first monomer are added to the solvent, the entire system is precooled at the reaction temperature for 5 to 20 minutes before adding the co-initiator.

[0025] Specifically, in the above preparation method, the system is polymerized for 5 to 30 minutes before adding the second portion of the first monomer.

[0026] Specifically, in the above preparation method, the second portion of the first monomer is added and the polymerization reaction is continued for 60 to 120 minutes before adding the end-capping agent.

[0027] Specifically, in the above preparation method, after adding the end-capping agent, the reaction is continued for 30 to 120 minutes before adding the regulating agent.

[0028] Specifically, in the above preparation method, after adding the regulator, the reaction is continued for 5 to 30 minutes before adding the second monomer.

[0029] Specifically, in the above preparation method, after adding the second monomer, the reaction is continued for 5 to 120 minutes before terminating the reaction. The terminating reaction is terminated by adding methanol.

[0030] Specifically, in the above preparation method, the conversion rate of the first monomer is 95-100%.

[0031] Specifically, in the above preparation method, the conversion rate of the second monomer is 10-70%.

[0032] The second technical problem to be solved by the present invention is to provide a polyisobutylene-based copolymer prepared by the above preparation method.

[0033] Furthermore, in the above polyisobutylene-based copolymer, the copolymer has a number average molecular weight of 1000 to 5×10 5 g / mol, and the molecular weight distribution is 1.01~1.30.

[0034] Furthermore, in the polyisobutylene-based copolymer, the mass fraction of the second monomer is 1 to 50 wt %, the conversion rate of the first monomer is 95 to 100%, and the conversion rate of the second monomer is 10 to 70%.

[0035] The third technical problem to be solved by the present invention is to provide a polymer obtained by crosslinking the above polyisobutylene-based copolymer. The crosslinking conditions are heating at 150-300° C. for 5-60 minutes.

[0036] The present invention prepares a polyisobutylene-based block copolymer with heat crosslinking, regular structural sequence, controllable content of each block and controllable molecular weight through living / controllable cationic polymerization, wherein polyisobutylene (PIB) is a soft segment and poly-4-vinylbenzocyclobutene (P-4VBCB) is a hard segment. The method of the present invention can well control the molecular weight and soft and hard segment ratio of the polyisobutylene-based block copolymer, and the polymer molecular weight distribution is narrow. The method of the present invention has the advantages of high monomer conversion rate and yield. The copolymer prepared by the method of the present invention has controllable molecular weight, crosslinking agent content and ordered structure, so that the yield and mechanical properties are greatly improved, and can be widely used in biomedicine, tire inner tubes, medical packaging, wires, cables, tapes, hoses, various mechanical products, vibration isolation parts, waterproof sheets for construction, sealing and caulking materials, chewing gum, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The schematic diagram is a structural diagram of the block copolymer prepared by using three different initiators.

[0038] Figure 2 This is the H NMR spectrum of the final product triblock copolymer of Example 2. The mass fraction of the second monomer in the polymer can be calculated by the integral value of the main characteristic peaks in this figure. The calculation method is as follows:

[0039] A / 4*130.19 / (A / 4*130.19+B / 6*56)*100, where A and B refer to the integral area of ​​characteristic peaks.

[0040] The mass fraction of the second monomer in the final product was calculated to be 9.81%.

[0041] Figure 3 This is the H NMR spectrum of the final product of the comparative example. The mass fraction of the second monomer is also calculated to be 1.61%.

[0042] Figure 4 The differential index (RI) spectra of the first monomer of the triblock copolymer at each reaction time in Example 2 show that all elution curves are normally distributed without tailing. As the reaction time increases, the peak time moves forward, indicating that the molecular weight continues to increase. It can be clearly seen that the reaction is an active / controllable polymerization.

[0043] Figure 5 The RI spectra of the second monomer samples of the triblock copolymer at different reaction times in Example 2 show that all elution curves are normally distributed without tailing. As the reaction time increases, the peak time moves forward, indicating that the molecular weight continues to increase. It can be clearly seen that the reaction is an active / controllable polymerization.

[0044] Figure 6 This is the SEC-MALS-UV-RI spectrum of the final product of the triblock copolymer described in Example 2. The UV, differential, and laser peak times are completely consistent, proving high block efficiency and that the second monomer and the first monomer have a uniform block structure.

[0045] Figure 7 The DSC spectra of the final product of Example 2 and the comparative example are compared. It is obvious from the DSC spectra that the final product of the comparative example only shows one glass transition temperature (Tg), while the final product of Example 2 has two obvious Tgs, which correspond to the Tgs of the respective homopolymers of the two segments. This well proves that the copolymer prepared by the present invention has a good block structure and has the properties of the respective homopolymers of the two segments.

[0046] Figure 8 The figure is a comparison of the mechanical properties of the products of Examples 1, 2, 3 and the comparative example after thermal crosslinking. It can be clearly seen from the figure that the maximum tensile strength and elongation at break of the products of the examples are much greater than those of the comparative example. When the mechanical properties of the examples and the comparative example of the present invention are tested, the copolymers formed into film sheets after thermal crosslinking are cut into dumbbell-shaped specimens according to the ASDM D-412 test standard, and three specimens are taken for each sample, and the results are averaged. DETAILED DESCRIPTION

[0047] It is well known in the professional field that in order to achieve high-efficiency block polymerization of multiple monomers in cationic polymerization, the reactivity between monomers must be similar. For example, the reactivity of IB is similar to that of styrene (St) monomers. Therefore, when preparing IB and St block copolymers, a simple sequential monomer addition method can be used to achieve cationic activity / controllable polymerization. However, compared with St, 4VBCB is a monomer with a condensed ring structure with a four-membered ring on a benzene ring. In the condensed ring structure, due to the increase in the number of rings, electrons can be distributed among more atoms, which may cause the electron density to be concentrated in certain areas. Due to the complexity of its structure and electron distribution, it may show higher reactivity at specific locations, thus resulting in the high reactivity of 4VBCB. At the same time, the inventors have also specifically verified through experiments that the reactivity of 4VBCB is higher than that of IB, and conventional reactions cannot introduce more 4VBCB, thereby making the resulting copolymer have higher mechanical properties. It can be seen that based on the huge differences in the monomer chemical structure, reactivity, polymerization rate, etc. between IB and 4VBCB, it is very difficult to achieve active / controllable cationic polymerization by simply adding monomers in sequence to obtain regular block copolymers.

[0048] The inventors have found through research that the polymerization of the first monomer IB is first initiated by the method of active / controllable cationic polymerization, and after most of the first monomer is converted, a capping agent is added to cap the first monomer to obtain a stable PIB+active center, and then a regulator is added to adjust the Lewis acidity of the system, the reactivity of the active center, etc., so that the chain growth rate of the second monomer is reduced and is less than the chain initiation rate; and then the second monomer is added to react to achieve efficient block, and the purpose of simply controlling the crosslinking agent content and molecular weight of the copolymer can be achieved by controlling the reaction time of the second monomer; after terminating the reaction, a block copolymer with an orderly and regular structure can be obtained. It can be seen that the method of the present invention can achieve the introduction of more second monomers, so that the crosslinking agent content of the product is higher, and then the mechanical properties of the obtained copolymer after crosslinking are better.

[0049] Specifically, the preparation method of the polyisobutylene-based copolymer of the present invention comprises the following steps: firstly, the glassware is baked and extracted to remove water and oxygen, and then placed in a glove box with an inert atmosphere, cooled to a reaction temperature of -50 to -100°C, solvent A and solvent B are added in sequence and continuously, fully mixed and precooled for 5 to 20 minutes, a proton scavenger, a main initiator, and a first part of the first monomer IB are added, fully mixed and precooled for 5 to 20 minutes, a co-initiator is added, and the second part of the first monomer IB is added after polymerization for 5 to 30 minutes, a capping agent is added after polymerization for 60 to 120 minutes, a regulator is added after 30 to 120 minutes, a mixture of a second monomer 4VBCB and solvent B is added after 5 to 30 minutes, and a mixture of a second monomer 4VBCB and solvent B is added after polymerization for 5 to 120 minutes, methanol is added to terminate the reaction, the product is precipitated with isopropanol, dissolved with cyclohexane, repeatedly washed, and dried to obtain the copolymer.

[0050] In the method of the present invention, the first monomer IB is added in two stages, the first part of the first monomer accounts for 5-30wt% of the total amount of the first monomer, and the second part of the first monomer accounts for 70-95% of the total amount of the first monomer. A small amount of the first monomer is first added to form a stable active center, and then a large amount of the first monomer is added to carry out chain growth, so that a large amount of concentrated heat release during the initiation process can be avoided to cause side reactions such as chain transfer.

[0051] In the method of the present invention, the mass fraction of the total mass of the first monomer and the second monomer in the reaction system is preferably controlled to be 10-50%. By controlling the concentration of the first monomer and the second monomer to be within this range, the degree of heat release can be controlled, which is beneficial to polymerization. The reaction system is the total mass of the entire system. The first monomer and the second monomer can be calculated by directly adding the amount.

[0052] In the method of the present invention, the molecular weight of the copolymer can be regulated by the ratio of the monomer to the initiator; at the same time, the longer the polymerization time of the second monomer and the higher the content of the second monomer, the greater the molecular weight of the copolymer.

[0053] In the method of the present invention, the reaction temperature of the entire system is controlled at -50 to -100° C., preferably -80° C. Once the temperature is determined, it is preferred that the temperature be maintained throughout the polymerization process, so each addition preferably has a precooling step.

[0054] In the method of the present invention, when the main initiator is When the polyisobutylene-based copolymer is obtained, the triblock copolymer P4VBCB-b-PIB-b-P4VBCB (poly (4-vinylbenzocyclobutene-b-polyisobutylene-b-polytetravinylphenylcyclobutene)) is obtained. Figure 1 When the main initiator is When the polyisobutylene-based copolymer is obtained, it is a three-arm star block copolymer, and all three arms are PIB-b-P4VBCB. The schematic diagram of the structure is shown in Figure 1When the primary initiator is 2-chloro-2,4,4-trimethylpentane (TMPCl), the resulting polyisobutylene-based copolymer is a diblock copolymer PIB-b-P4VBCB (polyisobutylene-b-polytetravinylphenylcyclobutene), the structural schematic diagram of which is shown in Figure 1 .

[0055] In the method of the present invention, the first monomer conversion rate is preferably controlled to be 95-100%, that is, 95-100% of the added first monomer participates in the reaction and becomes a part of the copolymer. The second monomer conversion rate is preferably controlled to be 10-70%, that is, 10-70% of the added second monomer participates in the reaction and becomes a part of the copolymer.

[0056] The polyisobutylene-based copolymer prepared by the method of the present invention has a number average molecular weight of 1000 to 5×10 5 g / mol, and the molecular weight distribution is 1.01~1.30.

[0057] The polyisobutylene-based copolymer prepared by the method of the present invention has a mass fraction of the second monomer of 1 to 50 wt%, that is, the content of the second monomer block in the finally obtained polyisobutylene-based copolymer is 1 to 50 wt%.

[0058] The polyisobutylene-based copolymer prepared by the method of the present invention has excellent mechanical properties and other effects after being heated at 150-300° C. for 5-60 minutes in a flat vulcanizer for thermal cross-linking molding.

[0059] Example 1 Synthesis of diblock copolymer PIB-b-P4VBCB (polyisobutylene-b-polytetravinylphenylcyclobutene)

[0060] Pour coolant into the cold trap of the anhydrous and oxygen-free glove box and cool it to -80°C. Place the dried polymerization bottle that has been baked and evacuated. Add 1L of a 60 / 40 volume ratio of methylcyclohexane / chloromethane mixed solvent, mix well and precool for 10 minutes. Add 0.143mL of a proton scavenger 2,6-di-tert-butylpyridine, 0.64mL of a primary initiator 2-chloro-2,4,4-trimethylpentane (TMPCl), and 0.143mL of a proton scavenger 2,6-di-tert-butylpyridine, 0.64mL of a primary initiator 2-chloro-2,4,4-trimethylpentane (TMPCl), and 0.143mL of a proton scavenger 2,6-di-tert-butylpyridine (TMPCl), and 0.143 ... primary initiator 2-chloro-2,4,4-trimethylpentane (TMPCl), and 0.143mL of a primary initiator 2-chloro-2,4,4-trimethylpentane (TMPCl), and 0.143mL of a primary initiator 2-chloro-2,4,4-trimethylpentane (TMPCl), and 0.143mL of a primary initiator 2-chloro-2,4,4-trimethylpentane (TMPCl), and 0.143mL of a primary initiator 2-chloro-2,4, After 5.6mL was precooled for 10min, 7.0mL of titanium tetrachloride as the co-initiator was added. After 20min of polymerization, 250mL of IB was added and the polymerization was continued for 80min. 0.15mL of end-capping agent 1,1-di-p-tolylethylene (DTE) was added. After 60min, 5.4mL of the regulator titanium isopropoxide (Ti(OiPr)4) was added. After 10min, 25mL of the second monomer 4-vinylbenzocyclobutene (4VBCB) was added. After 30min of polymerization, methanol was added to terminate the reaction. The product was precipitated with isopropanol, dissolved with cyclohexane, and dried after three times. 8g of the dried product was taken in a flat vulcanizer and thermally cross-linked at 200℃ for 25min.

[0061] Example 2 Synthesis of triblock copolymer P4VBCB-b-PIB-b-P4VBCB (poly (4-vinylbenzocyclobutene-b-polyisobutylene-b-polytetravinylphenylcyclobutene))

[0062] Pour coolant into the cold trap of the anhydrous and oxygen-free glove box and cool it to -80°C, put it into the dried polymerization bottle that has been baked and evacuated, add 1L of methylcyclohexane / chloromethane mixed solvent with a volume ratio of 60 / 40, mix well and precool for 10 minutes; add 0.143mL of proton scavenger 2,6-di-tert-butylpyridine, 0.79g of main initiator 5-tert-butyl-1,3-di(methylethylchloro)benzene, 5.6mL of IB1 in sequence, precool for 10 minutes, then add 7.0mL of co-initiator titanium tetrachloride, add 250mL of IB after 20 minutes of polymerization, and take 1mL of sample at polymerization times of 25, 50, 60, 70, and 90 minutes respectively, and terminate with methanol. After 100 minutes of polymerization, 0.15 mL of end-capping agent 1,1-di-p-tolylethylene (DTE) was added, 5.4 mL of regulating agent titanium isopropoxide (Ti(OiPr)4) was added after 60 minutes, and 25 mL of the second monomer 4-vinylbenzocyclobutene (4VBCB) was added after 10 minutes. 1 mL of samples were taken at polymerization times of 5, 10, 20, 30, 40, and 50 minutes, and methanol was added to terminate the reaction after 60 minutes of polymerization. The product was precipitated with isopropanol, dissolved with cyclohexane, and dried after three times. The final product was weighed to 62.4 g, and the comprehensive yield (total monomer mass / final product copolymer mass) was 94.5%. The product was then placed in a flat vulcanizer and thermally crosslinked at 240°C for 5 minutes.

[0063] Example 3 Synthesis of three-arm star block copolymer (PIB-b-P4VBCB) 3 (polyisobutylene-b-polytetravinylphenylcyclobutene) 3

[0064] Pour coolant into the cold trap of the anhydrous and oxygen-free glove box and cool it to -80°C, put in a dried polymerization bottle that has been baked and evacuated, add 1L of a 60 / 40 volume ratio of methylcyclohexane / methyl chloride mixed solvent, mix well and precool for 10 minutes; add 0.143mL of proton scavenger 2,6-di-tert-butylpyridine, 0.85g of the main initiator 1,3,5-tri(methylethylchloro)benzene, 5.6mL of IB1 in sequence, precool for 10 minutes, add 7.0mL of co-initiator titanium tetrachloride, add 50mL of IB2 after 20 minutes of polymerization, and continue polymerization for 80 minutes; add 0.15mL of end-capping agent 1,1-di-p-tolylethylene (DTE), add 6.8mL of regulator titanium isopropoxide (Ti(OiPr)4) after 60 minutes, add 32mL of the second monomer 4-vinylbenzocyclobutene (4VBCB) after 15 minutes, continue polymerization for 30 minutes, and then add methanol to terminate the reaction. The product was precipitated with isopropanol and then dissolved with cyclohexane, and the process was repeated three times before drying. 8 g of the dried product was placed in a flat vulcanizer at 240°C for 6 minutes to form a thermal cross-linking molding.

[0065] Comparative Example

[0066] Pour coolant into the cold trap of the anhydrous and oxygen-free glove box and cool it to -80°C. Put in the dried polymerization bottle after baking and exhaust, add 1L of methylcyclohexane / chloromethane mixed solvent with a volume ratio of 60 / 40, mix well and precool for 10 minutes; add 0.143mL of proton scavenger 2,6-di-tert-butylpyridine, 0.79g of main initiator 5-tert-butyl-1,3-di(methylethylchloro)benzene, 5.6mL of IB1 in turn, precool for 10 minutes, add 7.0mL of co-initiator titanium tetrachloride, add 250mL of IB and 25mL of the second monomer 4-vinylbenzocyclobutene (4VBCB) after 20 minutes of polymerization, and add methanol after 60 minutes of polymerization to terminate the reaction. The product was precipitated with isopropanol, dissolved with cyclohexane, repeated three times and dried. The final product was weighed 16.7g, with a comprehensive yield of 25.3%. Then the product was placed in a flat vulcanizer and thermally crosslinked at 240°C for 5 minutes.

Claims

1. A method for preparing a polyisobutylene-based copolymer, comprising the following steps: The first monomer IB is firstly initiated to polymerize by living / controllable cationic polymerization, and then a capping agent is added to cap the first monomer to obtain a stable PIB+ active center, and then a regulator is added to adjust the Lewis acidity and reaction activity of the system; then the second monomer 4-VBCB is added to continue the polymerization reaction, and the reaction is terminated and the polyisobutylene-based copolymer is obtained by post-treatment.

2. The method for preparing the polyisobutylene-based copolymer according to claim 1, comprising the following steps: A proton scavenger, a main initiator, a first part of the first monomer IB, and a co-initiator are subjected to polymerization reaction in a solvent, and then the second part of the first monomer IB is added to continue the polymerization reaction until the conversion rate of the first monomer is above 95%; then a capping agent is added to perform end-capping to obtain a stable PIB+ active center, and then a regulator is added to adjust the Lewis acidity and reaction activity of the system; then the second monomer 4-VBCB is added to continue the polymerization reaction, the reaction is terminated, and the polyisobutylene-based copolymer is obtained through post-treatment.

3. The preparation method according to claim 1 or 2, characterized in that: The end-capping agent is at least one of 1,1-diphenylethylene, 1,1-di-p-tolylethylene, 2-methylfuran, and 2-tert-butylfuran; preferably, the end-capping agent is 1,1-diphenylethylene or 1,1-di-p-tolylethylene.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The regulator is at least one of Ti(OR)4, SnBr4, SnCl4, n-Bu4NCl, BCl3, wherein R is C 1-4 Alkyl; preferably the regulator is titanium isopropoxide or Bu4NCl.

5. The preparation method according to any one of claims 1 to 4, characterized in that: At least one of the following is met: The main initiator is -2,4,4-trimethylpentane; wherein R1 is methyl, Cl or methoxy, and R2 and R3 are each independently Cl or methoxy; The co-initiator is at least one of titanium tetrachloride, ferric chloride, boron trifluoride, boron trichloride, gallium trichloride, aluminum chloride, and alkyl aluminum chloride; preferably, the co-initiator is titanium tetrachloride; The proton scavenger is at least one of 2,6-di-tert-butylpyridine, 2,6-di-tert-butyl-4-methylpyridine, and 2,4,6-tri-tert-butylpyridine; preferably, the proton scavenger is 2,6-di-tert-butylpyridine; The solvent is a mixed solvent of solvent A and solvent B; wherein solvent A is at least one of methyl chloride, dichloromethane, and chloroform, and solvent B is at least one of n-hexane, cyclohexane, and methylcyclohexane; further, the volume ratio B / A of the mixed solvent is 7:3, 6:4, or 5:

5.

6. The preparation method according to any one of claims 1 to 5, characterized in that: At least one of the following is met: The molar ratio of the first monomer to the second monomer is (60-99):(40-1); The molar ratio of the main initiator to the first monomer is 1:(50-1000); The molar ratio of the main initiator to the co-initiator is 1:(2-64); The molar ratio of the end-capping agent to the main initiator is 1:(1-10); The molar ratio of the regulator to the end-capping agent is (1-64):1; The molar ratio of the proton scavenger to the end-capping agent is 1:(1-10); The first part of the first monomer accounts for 5-30wt% of the total amount of the first monomer, and the second part of the first monomer accounts for 70-95wt% of the total amount of the first monomer; The mass fraction of the total mass of the first monomer and the second monomer in the reaction system is 10-50%.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The reaction temperature is -50 to -100°C, preferably -80°C.

8. The preparation method according to any one of claims 1 to 7, characterized in that: At least one of the following conditions is met: the solvent is precooled at the reaction temperature for 5 to 20 minutes before adding the proton scavenger, the main initiator, and the first part of the first monomer; after the proton scavenger, the main initiator, and the first part of the first monomer are added to the solvent, the entire system is precooled at the reaction temperature for 5 to 20 minutes before adding the co-initiator; After the system undergoes polymerization reaction for 5 to 30 minutes, the second portion of the first monomer is added; Add the second part of the first monomer and continue the polymerization reaction for 60 to 120 minutes before adding the end-capping agent; After adding the end-capping agent, continue the reaction for 30 to 120 minutes before adding the regulator; After adding the regulator, continue the reaction for 5 to 30 minutes before adding the second monomer; After adding the second monomer, the reaction is continued for 5 to 120 minutes and then terminated; The second monomer conversion rate is 10-70%.

9. The polyisobutylene-based copolymer prepared by the preparation method according to any one of claims 1 to 8.

10. The polyisobutylene-based copolymer according to claim 9, characterized in that: The number average molecular weight is 1000~5×10 5 g / mol, molecular weight distribution is 1.01~1.30; Furthermore, the mass fraction of the second monomer is 1 to 50 wt %.

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