Preparation method of silicon-containing brush polymer

Abstract

The invention discloses a preparation method of a silicon-containing brush polymer, which comprises the following steps: adding a monomer with double bonds and silicon-hydrogen bonds capable of free radical polymerization and a free radical polymerization initiator into an organic solvent, adding a hydrosilylation catalyst, carrying out polymerization reaction, and after the reaction is finished, carrying out post-treatment purification to obtain the silicon-containing brush polymer. The silicon-containing brush-like polymer is prepared through binary polymerization of a single monomer, and the method has the advantages that 1) the method is suitable for monomers of various different systems; 2) the reaction is easy to realize, and a special device is not needed; and 3) the brush polymer can be efficiently obtained under the ppm-level catalyst content. The invention can be used in scenarios involving the synthesis of brush polymers by free radical polymerization and hydrosilylation polymerization.

Description

Technical Field

[0001] The invention relates to the technical field of brush polymer preparation, and in particular to a method for preparing a silicon-containing brush polymer. Background Art

[0002] Brush polymers are defined as multiple polymer brushes densely grafted onto a polymer backbone. Due to their unique structure and properties, brush polymers are widely used in the fields of self-assembly and nanomaterials.

[0003] There are three main strategies for synthesizing well-defined bottle brushes: "grafting from", "grafting through" and "grafting onto". Using these strategies, researchers have prepared linear, star-shaped and "sun-shaped" brush (co)polymers, respectively. Such processes have long reaction times, cumbersome purification procedures, and often lead to unpredictable polymerization products due to steric site resistance. In addition, the "grafting onto" process couples side chains to the main chain, usually exhibits low grafting efficiency, and requires further purification to remove unreacted side chains. Therefore, a simpler and more effective method, namely a binary polymerization method, is needed when synthesizing brush polymers.

[0004] Silicon-containing polymers, or preceramic polymers, offer advantages in ceramic production, including the production of high-performance ceramic fibers and composites and the preparation of ceramics with diverse compositions, such as SiC, Si3N4, and SiCN. The unique properties of these preceramic polymers are manifold, including the ability to be processed using established methods and subsequently heat treated to produce inorganic replicas of the polymer shape. Therefore, the development of synthetic methods for silicon-containing polymers is of great interest. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a silicon-containing brush polymer in view of the deficiencies in the prior art.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] Provided is a method for preparing a silicon-containing brush polymer, comprising taking a monomer having a double bond and a silicon-hydrogen bond capable of free radical polymerization and a free radical polymerization initiator in an organic solvent, adding a silicon hydroaddition catalyst, and performing a polymerization reaction. After the reaction is completed, post-treatment and purification are performed to obtain the silicon-containing brush polymer.

[0008] Furthermore, the monomer has a structural formula of one or more of formula (I), formula (II), and formula (III);

[0009]

[0010] Wherein, n is the length of the alkyl chain, n=0-20, and is an integer; R is a functional group connected to silicon, and is one or more of an alkyl group, a phenyl group, and a cyclohexyl group with a length of 1-10.

[0011] Furthermore, the molar ratio of the monomer, the free radical polymerization initiator and the hydrosilylation catalyst is 100:(1-4):(0.0001-0.002).

[0012] Furthermore, the free radical polymerization initiator is one or more of the photoinitiator benzoin dimethyl ether, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, and the thermal initiator azobisisobutylcyanide.

[0013] Furthermore, the polymerization reaction temperature is the applicable temperature of the free radical polymerization initiator, which is 0-100° C.; and the polymerization reaction time is 1-48 hours.

[0014] Furthermore, the hydrosilylation catalyst is one or more of a Custer catalyst, platinum acetylacetonate, and a SPEIER catalyst.

[0015] Furthermore, the organic solvent is one or more of tetrahydrofuran, 1,4-dioxane, ether, dichloromethane, ethylene glycol dimethyl ether, methyl tert-butyl ether, and acetone.

[0016] Furthermore, the concentration of the hydrosilylation catalyst in the polymerization reaction system is 10-2000 ppm.

[0017] The present invention adopts the above technical solution, and has the following technical effects compared with the prior art:

[0018] The present invention prepares a silicon-containing brush polymer by binary polymerization of a single monomer. 1) It is applicable to monomers of various different systems; 2) The reaction is easy to achieve without the need for special equipment; 3) The brush polymer can be efficiently obtained at a catalyst content of ppm level. The present invention can be applied to scenarios involving free radical polymerization and hydrosilylation polymerization to synthesize brush polymers. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the free radical polymerization kinetic curve of (4-vinylphenyl)dimethylsilane monomer initiated by 1 mol% benzoin dimethyl ether.

[0020] Figure 2 The hydrosilylation reaction kinetics of (4-vinylphenyl)dimethylsilane monomer catalyzed by 10 ppm KARSTEDT catalyst.

[0021] Figure 3The free radical polymerization of (4-vinylphenyl)dimethylsilane monomer initiated by 1 mol% benzoin dimethyl ether and the hydrosilylation reaction catalyzed by 10 ppm KARSTEDT catalyst and the binary polymerization kinetics of the two.

[0022] Figure 4 This is the NMR spectrum of the brush polymer PPVSi-g-PPESi.

[0023] Figure 5 This is the GPC elution curve of the brush polymer PPVSi-g-PPESi.

[0024] Figure 6 The H-NMR spectrum (left) and C-NMR spectrum (right) of 4-(dimethylsilyl)phenyl)dimethyl(4-(oxiran-2-yl)butyl)silane.

[0025] Figure 7 The H NMR spectrum (left) and C NMR spectrum (right) of 6-((4-(dimethylsilyl)phenyl)dimethylsilyl)hexan-2-ol.

[0026] Figure 8 This is the H-NMR spectrum (left) and C-NMR spectrum (right) of 5-((4-(dimethylsilyl)phenyl)dimethylsilyl)pentyl acrylate.

[0027] Fig. 9 The hydrosilylation reaction kinetics of monomer HA catalyzed by 200 ppm SPEIER catalyst.

[0028] Fig.10 This is the free radical polymerization kinetic curve of monomer HA initiated by 0.5 mol% benzoin dimethyl ether.

[0029] Fig.11 The kinetics of the free radical polymerization of HA monomer initiated by 0.5 mol% benzoin dimethyl ether and the hydrosilylation reaction catalyzed by 200 ppm SPEIER catalyst and the binary polymerization kinetics of the two.

[0030] Fig.12 This is the GPC elution curve of the brush polymer PHA-g-PHB. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but is not intended to be limiting of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention may be combined with each other without conflict.

[0032] The present invention is further described in detail below in conjunction with specific embodiments. First, we studied the reaction kinetics of monomers in free radical polymerization, hydrosilylation, and binary polymerization in which the two are combined, and studied the mutual relationship between the two reactions. From the following implementation case, it can be seen that the two reactions are orthogonal reactions, based on which the rates of the two reactions are changed to adjust the side chain length of the final polymer. And the method is extended to acrylate monomers.

[0033] Example 1 Free Radical Polymerization of PVSi

[0034] The monomer (4-vinylphenyl) dimethylsilane (PVSi) (324 mg, 2 mmol) and benzoin dimethyl ether (5 mg, 0.02 mmol) were placed in a 2 ml stirring bottle with a magnetic pole, and then placed under a 10W 365 nm ultraviolet lamp to react at room temperature. The monomer conversion rate of the reaction was tracked by nuclear magnetic resonance, and its kinetic curve is shown in the attached figure. Figure 1 The above processes were all carried out in a glove box.

[0035] Example 2 Hydrosilylation Polymerization of PVSi

[0036] Preparation of catalyst solution: Take 40 μl of the purchased KARSTEDT catalyst (2% xylene solution) and add it to 20 ml of anhydrous xylene solution, and stir it thoroughly.

[0037] Polymerization reaction: Add the monomer (4-vinylphenyl) dimethylsilane (PVSi) (324 mg, 2 mmol) and 7.5 μl of the catalyst solution into a 2 ml stirring bottle with a magnetic pole and react at room temperature. The monomer conversion rate of the reaction is tracked by nuclear magnetic resonance. The kinetic curve is shown in the attached figure. Figure 2 The above process is carried out in the glove box.

[0038] Example 3 Binary Polymerization of PVSi

[0039] The monomer (4-vinylphenyl) dimethylsilane (PVSi) (324 mg, 2 mmol), benzoin dimethyl ether (5 mg, 0.02 mmol) and 7.5 μl of the catalyst solution were added to a 2 ml stirring bottle with a magnetic pole, and then placed under a 10W 365 nm ultraviolet lamp to react at room temperature. The monomer conversion rate of the reaction was tracked by nuclear magnetic resonance, and its kinetic curve was compared with the kinetics previously made, as shown in the attached figure. Figure 3 The above processes were all carried out in a glove box.

[0040] As attached Figure 3As shown in the figure, the kinetic curves of free radical polymerization and hydrosilylation polymerization in binary polymerization are similar to those of their respective reactions, which are almost orthogonal reactions. Under this condition, increasing the length of the side chain, that is, increasing the rate of hydrosilylation, increases the proportion of the side chain in the total to synthesize brush polymers.

[0041] The chemical reaction formula is as follows:

[0042]

[0043] Example 4 Synthesis of brush polymer PPVSi-g-PPESi

[0044] The monomer (4-vinylphenyl) dimethylsilane (PVSi) (324 mg, 2 mmol), benzoin dimethyl ether (10 mg, 0.04 mmol) and 150 μl of the catalyst solution were added to a 2 ml stirring bottle with a magnetic pole containing 300 μl of 1,4-dioxane, and then placed under a 10W 365nm ultraviolet lamp and reacted at room temperature for 5 hours. After the reaction was completed, it was diluted with tetrahydrofuran, precipitated in methanol, and dried. The average length of its side chain was calculated by nuclear magnetic resonance to be 8.1, as shown in the attached Figure 4 As shown in the figure, and the molecular weight determined by GPC is 15000; the molecular weight distribution is 3.73, as shown in the attached Figure 5 shown.

[0045] Example 5

[0046] This example provides a synthetic route for acrylic acid ester-containing silicon-hydrogen monomers:

[0047]

[0048] 5.1. Synthesis of (4-(dimethylsilyl)phenyl)dimethyl(4-(oxiran-2-yl)butyl)silane

[0049] In a three-necked flask equipped with a constant pressure dropping funnel, take 1,2-epoxy-5-hexene (9.8 g, 0.1 mol) and 10 ml of tetrahydrofuran into the constant pressure dropping funnel, and 1,4-bis(dimethylsilyl)benzene (77.6 g, 0.4 mol) into the three-necked flask, and pass argon protection. After dropping 5 ml of 1,2-epoxy-5-hexene solution, add 1 drop of KARSTEDT catalyst, then raise the temperature to 35°C, slowly drop 1,2-epoxy-5-hexene solution, remove heating after the addition is complete, stir at room temperature, and track the reaction with a spot plate until the reaction is complete. After the reaction is complete, purify by column chromatography, and determine the structure by NMR, as shown in the attached Figure 6 shown.

[0050] 5.2. Synthesis of 6-((4-(dimethylsilyl)phenyl)dimethylsilyl)hexan-2-ol (4-(dimethylsilyl)phenyl)dimethyl(4-(oxiran-2-yl)butyl)silane (25 g, 0.085 mol) was dissolved in anhydrous tetrahydrofuran, and argon was passed through. Then, an excess of lithium aluminum hydride powder (4.1 g, 0.1 mol) was added and reacted at room temperature overnight. After the reaction was completed, water was added to quench the lithium aluminum hydride, and after extraction and drying, it was purified by vacuum distillation at 140°C. The structure was determined by NMR, as shown in the attached figure. Figure 7 shown.

[0051] 5.3 Synthesis of 5-((4-(dimethylsilyl)phenyl)dimethylsilyl)pentyl acrylate (HA)

[0052] Dissolve 6-((4-(dimethylsilyl)phenyl)dimethylsilyl)hexan-2-ol (2.94 g, 0.01 mol) and triethylamine (1.5 g, 0.015 mol) in 20 ml of anhydrous tetrahydrofuran, slowly drop acryloyl chloride (1.35 g, 0.015 mol) in 20 ml of tetrahydrofuran under argon protection at 0°C. After the dropwise addition, move the reaction to room temperature and react overnight. After the reaction is completed, purify by column chromatography. Determine the structure by NMR, as shown in the attached Figure 8 The product contains some isomers generated during the reduction of epoxide, which are marked in the NMR image, but have no effect on the synthesis of brush polymers.

[0053] Example 6 Hydrosilylation Polymerization of HA

[0054] Catalyst solution (SPEIER catalyst) preparation: 1 g of purchased chloroplatinic acid hexahydrate was dissolved in 100 ml of anhydrous tetrahydrofuran and then allowed to stand for 1 day.

[0055] Polymerization reaction: Add the monomer 5-((4-(dimethylsilyl)phenyl)dimethylsilyl)pentyl acrylate (348 mg, 1 mmol) and 12 μl of the catalyst solution into a 2 ml stirring bottle with a magnetic pole and react at room temperature. The monomer conversion rate of the reaction was tracked by nuclear magnetic resonance. The kinetic curve is shown in the attached figure. Fig. 9 The above processes were all carried out in a glove box, and the product structure is shown below, denoted as PHB.

[0056]

[0057] Example 7 Free Radical Polymerization of HA

[0058] The monomer HA (348 mg, 1 mmol) and dimethyl benzoate (2.5 mg, 0.005 mmol) were placed in a 2 ml stirring bottle with a magnetic pole, and then placed under a 10W 365 nm ultraviolet lamp for reaction at room temperature. The monomer conversion rate of the reaction was tracked by nuclear magnetic resonance, and the kinetic curve is shown in the attached figure. Fig.10 The above processes were all carried out in a glove box, and the product structure is shown below, denoted as PHA.

[0059]

[0060] Example 8 Binary Polymerization of HA

[0061] The monomer HA (348 mg, 1 mmol), dimethyl benzoate (2.5 mg, 0.005 mmol) and 4 μl of the catalyst solution were added to a 2 ml stirring bottle with a magnetic pole, and then placed under a 10W 365 nm UV lamp to react at room temperature. The monomer conversion rate of the reaction was tracked by nuclear magnetic resonance, and its kinetic curve was compared with the previous kinetics, as shown in the attached figure. Fig.11 The above processes were all carried out in a glove box.

[0062] From the three reaction kinetics, it can be seen that, like styrene monomers, free radical polymerization and hydrosilylation polymerization of acrylic monomers are nearly orthogonal reactions, and brush polymers can be prepared as in the above case.

[0063] Example 9 Synthesis of Brush Polymer PHA-g-PHB

[0064] Add monomer HA (348 mg, 1 mmol), benzoin dimethyl ether (2.5 mg, 0.005 mmol) and 4 μl of catalyst solution to a 2 ml stirring bottle with a magnetic pole containing 300 μl of 1,4-dioxane, and then place it under a 10W 365nm ultraviolet lamp and react at room temperature for 5 hours. After the reaction is completed, dilute with tetrahydrofuran, precipitate in methanol, and dry. The chemical reaction equation is as follows:

[0065]

[0066] The molecular weight determined by GPC is 16000; the molecular weight distribution is 4.6. Fig.12 shown.

[0067] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a silicon-containing brush polymer, characterized in that: A monomer with double bonds and silicon-hydrogen bonds capable of free radical polymerization and a free radical polymerization initiator are placed in an organic solvent, and a silicon hydroaddition catalyst is added to carry out a polymerization reaction. After the reaction is completed, post-treatment and purification are carried out to obtain the silicon-containing brush polymer.

2. The method for preparing a silicon-containing brush polymer according to claim 1, characterized in that: The monomer is one or more of the structural formulas of formula (I), formula (II), and formula (III); Wherein, n is the length of the alkyl chain, n=0-20, and is an integer; R is a functional group connected to silicon, and is one or more of an alkyl group, a phenyl group, and a cyclohexyl group with a length of 1-10.

3. The method for preparing a silicon-containing brush polymer according to claim 1, characterized in that: The molar ratio of the monomer, the free radical polymerization initiator and the hydrosilylation catalyst is 100:(1-4):(0.0001-0.002).

4. The method for preparing a silicon-containing brush polymer according to claim 1, characterized in that: The free radical polymerization initiator is one or more of the photoinitiator benzoin dimethyl ether, 2,4,6-trimethylbenzoylphenyl phosphonic acid ethyl ester, and the thermal initiator azobisisobutyl cyanide.

5. The method for preparing a silicon-containing brush polymer according to claim 4, characterized in that: The polymerization reaction temperature is the applicable temperature of the free radical polymerization initiator, which is 0-100° C.; the polymerization reaction time is 1-48 hours.

6. The method for preparing a silicon-containing brush polymer according to claim 1, characterized in that: The hydrosilylation catalyst is one or more of a Custer catalyst, platinum acetylacetonate, and a SPEIER catalyst.

7. The method for preparing a silicon-containing brush polymer according to claim 1, characterized in that: The organic solvent is one or more of tetrahydrofuran, 1,4-dioxane, ether, dichloromethane, ethylene glycol dimethyl ether, methyl tert-butyl ether and acetone.

8. The method for preparing a silicon-containing brush polymer according to claim 1, characterized in that: The concentration of the hydrosilylation catalyst in the polymerization reaction system is 10-2000 ppm.

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