A method for preparing a silicon-containing brush polymer

Abstract

This invention discloses a method for preparing a silica-containing brush polymer. A monomer containing double bonds and silane-hydrogen bonds capable of free radical polymerization, along with a free radical polymerization initiator, are placed in an organic solvent. A hydrosilylation catalyst is then added to initiate the polymerization reaction. After the reaction, post-treatment purification is performed to obtain the silica-containing brush polymer. This invention prepares silica-containing brush polymers through binary polymerization of a single monomer, which: 1) is applicable to monomers in various systems; 2) the reaction is easy to implement and does not require special equipment; and 3) brush polymers can be obtained efficiently at ppm-level catalyst concentrations. This invention can be applied to scenarios involving the synthesis of brush polymers through free radical polymerization and hydrosilylation polymerization.

Description

Technical Field

[0001] This invention relates to the field of brush polymer preparation technology, and more particularly to a method for preparing a silicon-containing brush polymer. Background Technology

[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 fields such as self-assembly and nanomaterials.

[0003] There are three main strategies for synthesizing well-defined bottle brushes: "grafting from," "grafting through," and "grafting onto." Researchers have used these strategies to prepare linear, star-shaped, and "sun-shaped" brush-like (co)polymers, respectively. These processes are time-consuming, involve cumbersome purification procedures, and often result in unpredictable polymerization products due to steric hindrance. Furthermore, the "grafting onto" process couples side chains to the main chain, typically exhibiting low grafting efficiency and requiring further purification to remove unreacted side chains. Therefore, a simpler and more efficient method, namely binary polymerization, is needed for synthesizing brush-like polymers.

[0004] Silicon-containing polymers, also known as ceramic precursor polymers, offer advantages in ceramic production, including the production of high-performance ceramic fibers and composites, as well as the preparation of ceramics with diverse compositions (such as SiC, Si3N4, and SiCN). These ceramic precursor polymers possess unique properties, including the ability to be processed using established methods and subsequently heat-treated to produce inorganic replicas of the polymer shape. Therefore, developing synthetic methods for silicon-containing polymers is of great significance. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing a silicon-containing brush polymer.

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

[0007] A method for preparing a silicon-containing brush polymer is provided, comprising taking a monomer with double bonds and silane-hydrogen bonds capable of free radical polymerization and a free radical polymerization initiator in an organic solvent, then adding a hydrosilylation catalyst to carry out a polymerization reaction, and performing post-treatment purification after the reaction is completed to obtain the silicon-containing brush polymer.

[0008] Furthermore, the monomer is one or more of the structural formulas (I), (II), and (III);

[0009]

[0010] Where n is the length of the alkyl chain, n = 0-20, and is an integer; R is the functional group attached to silicon, which is one or more of alkyl, phenyl, and cyclohexyl groups 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 following: photoinitiator dimethyl benzoate, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, and thermal initiator azobisisobutyronitrile.

[0013] Furthermore, the polymerization temperature is the applicable temperature for the free radical polymerization initiator, which is 0-100℃; the polymerization time is 1-48 hours.

[0014] Furthermore, the hydrosilylation catalyst is one or more of the following: a Castells catalyst, a platinum acetylacetonate catalyst, and a Speiner catalyst.

[0015] Furthermore, the organic solvent is one or more of tetrahydrofuran, 1,4-dioxane, diethyl 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] This invention prepares silica-containing brush-like polymers through binary polymerization of a single monomer. The advantages are: 1) applicability to various monomer systems; 2) easy reaction implementation without requiring special equipment; and 3) efficient yield of brush-like polymers at ppm-level catalyst concentrations. This invention can be applied to scenarios involving free radical polymerization and hydrosilylation polymerization for the synthesis of brush-like polymers. Attached Figure Description

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

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

[0021] Figure 3The kinetics of the 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, as well as the binary polymerization kinetics of both.

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

[0023] Figure 5 The GPC effluent profiles are for the brushed polymer PPVSi-g-PPESi.

[0024] Figure 6 The 1H NMR spectrum (left) and 1C NMR spectrum (right) of 4-(dimethylsilyl)phenyl)dimethyl(4-(ethylene oxide-2-yl)butyl)silane.

[0025] Figure 7 The 1H NMR spectrum (left) and 1C NMR spectrum (right) of 6-((4-(dimethylsilyl)phenyl)dimethylsilyl)hex-2-ol.

[0026] Figure 8 The left and right NMR spectra of 5-((4-(dimethylsilyl)phenyl)dimethylsilyl)pentyl acrylate are shown.

[0027] Figure 9 The kinetics of the hydrosilylation reaction of monomer HA under the catalysis of 200 ppm SPEIER catalyst are presented.

[0028] Figure 10 The graph shows the free radical polymerization kinetics of monomer HA initiated by 0.5 mol% benzoin dimethyl ether.

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

[0030] Figure 12 The GPC effluent profile of the brush polymer PHA-g-PHB is shown. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0032] The invention will now be described in further detail with reference to specific embodiments. First, we studied the reaction kinetics of monomers in free radical polymerization, hydrosilylation, and binary polymerization combining both, investigating the simultaneous interaction of the two reactions. As shown in the following examples, the two reactions are orthogonal. Based on this, by changing the rates of the two reactions, the side chain length of the polymer can be obtained. This method is then extended to acrylate monomers.

[0033] Example 1: Free radical polymerization of PVSi

[0034] The monomer (4-vinylphenyl)dimethylsilane (PVSi) (324 mg, 2 mmol) and dimethyl benzoate (5 mg, 0.02 mmol) were placed in a 2 ml stirred flask equipped with a magnetic stir bar and then placed under a 10 W 365 nm UV lamp for irradiation at room temperature. The monomer conversion rate of this reaction was tracked by nuclear magnetic resonance, and the kinetic curve is shown in the attached figure. Figure 1 As shown. All of the above processes are carried out in the glove box.

[0035] Example 2 Hydrosilylation Polymerization of PVSi

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

[0037] Polymerization reaction: 324 mg (2 mmol) of monomer (4-vinylphenyl)dimethylsilane (PVSi) and 7.5 μl of catalyst solution were added to a 2 mL stirred flask equipped with a magnetic stir bar, and the reaction was carried out at room temperature. The monomer conversion rate was monitored using nuclear magnetic resonance, and the kinetic curve is shown in the attached figure. Figure 2 The above processes all take place inside the glove box.

[0038] Example 3: Binary Polymerization of PVSi

[0039] The monomer (4-vinylphenyl)dimethylsilane (PVSi) (324 mg, 2 mmol), dimethyl benzoate (5 mg, 0.02 mmol), and 7.5 μl of catalyst solution were added to a 2 mL stirred flask equipped with a magnetic stir bar and then placed under a 10 W 365 nm UV lamp for irradiation at room temperature. The monomer conversion rate of this reaction was tracked by nuclear magnetic resonance, and its kinetic curve was compared with the previously obtained kinetic curve, as shown in the attached figure. Figure 3 As shown. All of the above processes are carried out in the glove box.

[0040] As attached Figure 3As shown, the kinetic curves of free radical polymerization and hydrosilylation polymerization in binary polymerization are similar to those of their individual reactions, exhibiting almost orthogonal behavior. Under these conditions, increasing the side chain length, i.e., increasing the hydrosilylation rate, increases the proportion of side chains in the total polymer, thereby synthesizing brush-like polymers.

[0041] Its 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), dimethyl benzoate (10 mg, 0.04 mmol), and 150 μl of catalyst solution were added to a 2 mL stirred flask equipped with a magnetic stirrer containing 300 μl of 1,4-dioxane. The flask was then irradiated under a 10W 365 nm UV lamp and reacted at room temperature for 5 hours. After the reaction was complete, the solution was diluted with tetrahydrofuran, precipitated in methanol, and dried. The average length of the side chain was calculated to be 8.1 mm using NMR spectroscopy. Figure 4 As shown, and determined by GPC, its molecular weight is 15,000; its molecular weight distribution is 3.73, as shown in the attached figure. Figure 5 As shown.

[0045] Example 5

[0046] This embodiment provides a synthetic route for acrylate monomers containing silane:

[0047]

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

[0049] In a three-necked flask equipped with a constant-pressure dropping funnel, 9.8 g (0.1 mol) of 1,2-epoxy-5-hexene and 10 mL of tetrahydrofuran were added to the constant-pressure dropping funnel, and 77.6 g (0.4 mol) of 1,4-di(dimethylsilyl)benzene was added to the three-necked flask. Argon gas was purged through the flask for protection. After adding 5 mL of the 1,2-epoxy-5-hexene solution, one drop of KARSTEDT catalyst was added. The temperature was then raised to 35 °C, and the 1,2-epoxy-5-hexene solution was slowly added dropwise. After the addition was complete, the heating was removed, and the mixture was stirred at room temperature. The reaction was monitored by TLC until completion. After the reaction was complete, the solution was purified by column chromatography, and the structure was determined by NMR, as shown in the attached figure. Figure 6 As shown.

[0050] 5.2 Synthesis of 6-((4-(dimethylsilyl)phenyl)dimethylsilyl)hex-2-ol: (4-(dimethylsilyl)phenyl)dimethyl(4-(ethyleneoxy-2-yl)butyl)silane (25 g, 0.085 mol) was dissolved in anhydrous tetrahydrofuran under argon protection. Then, excess lithium aluminum hydride powder (4.1 g, 0.1 mol) was added, and the reaction was carried out overnight at room temperature. After the reaction was complete, the lithium aluminum hydride was quenched with water, extracted, dried, and purified by vacuum distillation at 140 °C. The structure was confirmed by NMR, as shown in the attached figure. Figure 7 As shown.

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

[0052] 6-((4-(dimethylsilyl)phenyl)dimethylsilyl)hex-2-ol (2.94 g, 0.01 mol) and triethylamine (1.5 g, 0.015 mol) were dissolved in 20 mL of anhydrous tetrahydrofuran. Acryloyl chloride (1.35 g, 0.015 mol) was added dropwise to 20 mL of tetrahydrofuran under argon protection and at 0 °C. After the addition was complete, the reaction was allowed to proceed to room temperature overnight. The reaction was then purified by column chromatography. The structure was confirmed by NMR, as shown in the attached figure. Figure 8 As shown. The product contains some isomers generated during epoxy reduction, which are marked in the NMR spectrum, but they have no effect on the synthesis of brush polymers.

[0053] Example 6 Hydrosilylation Polymerization of HA

[0054] Preparation of catalyst solution (SPEIER catalyst): Dissolve 1g of purchased chloroplatinic acid hexahydrate in 100ml of anhydrous tetrahydrofuran, and then let it stand for 1 day.

[0055] Polymerization reaction: 348 mg (1 mmol) of monomer 5-((4-(dimethylsilyl)phenyl)dimethylsilyl)pentyl acrylate and 12 μl of catalyst solution were added to a 2 mL stirred flask equipped with a magnetic stir bar and reacted at room temperature. The monomer conversion rate of this reaction was tracked by nuclear magnetic resonance, and the kinetic curve is shown in the attached figure. Figure 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 stirred flask equipped with a magnetic stir bar and then placed under a 10 W 365 nm UV lamp for irradiation at room temperature. The monomer conversion rate of this reaction was tracked by nuclear magnetic resonance, and the kinetic curve is shown in the attached figure. Figure 10 As shown. The above processes were all carried out in a glove box, and the product structure is shown below, denoted as PHA.

[0059]

[0060] Binary polymerization of HA in Example 8

[0061] The monomer HA (348 mg, 1 mmol), dimethyl benzoate (2.5 mg, 0.005 mmol), and 4 μl of catalyst solution were added to a 2 ml stirred flask equipped with a magnetic stir bar. The flask was then placed under a 10 W 365 nm UV lamp and reacted at room temperature. The monomer conversion rate of this reaction was tracked using nuclear magnetic resonance (NMR), and its kinetic curve was compared with the previously obtained kinetic curve, as shown in the attached figure. Figure 11 As shown. All of the above processes are carried out in the glove box.

[0062] As can be seen from the three reaction kinetics, acrylate monomers, like styrene monomers, undergo near-orthogonal reactions in both free radical polymerization and hydrosilylation polymerization, and can be used to prepare brush polymers in the same way as in the above case.

[0063] Example 9: Synthesis of the brush polymer PHA-g-PHB

[0064] The monomer HA (348 mg, 1 mmol), benzoin dimethyl ether (2.5 mg, 0.005 mmol), and 4 μl of catalyst solution were added to a 2 mL stirred flask equipped with a magnetic stirrer containing 300 μl of 1,4-dioxane. The flask was then irradiated under a 10W 365 nm UV lamp and reacted at room temperature for 5 hours. After the reaction was complete, the solution was diluted with tetrahydrofuran, precipitated in methanol, and dried. The chemical reaction equation is shown below:

[0065]

[0066] Its molecular weight, determined by GPC, is 16,000; its molecular weight distribution is 4.6, as shown in the attached figure. Figure 12 As shown.

[0067] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the content and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a silicon-containing brush-like polymer, characterized in that, Monomers containing double bonds and silane bonds capable of free radical polymerization and free radical polymerization initiators are placed in an organic solvent, and then a hydrosilylation catalyst is added to carry out a polymerization reaction. After the reaction is completed, post-treatment purification is performed to obtain the silicon-containing brush polymer. The monomer is one or more of the structural formulas (Ⅰ), (Ⅱ), and (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, which is one or more of alkyl, phenyl, and cyclohexyl groups with a length of 1-10; the molar ratio of the monomer, free radical polymerization initiator and hydrosilylation catalyst is 100:(1-4):(0.0001-0.002); The hydrosilylation catalyst is one or more of the following: Castella catalyst, platinum acetylacetonate catalyst, and SPEIER catalyst; the concentration of the hydrosilylation catalyst in the polymerization reaction system is 10-2000 ppm.

2. The method for preparing the silicon-containing brush-like polymer according to claim 1, characterized in that, The free radical polymerization initiator is one or more of the following: photoinitiator dimethyl benzoate, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, and thermal initiator azobisisobutyronitrile.

3. The method for preparing the silicon-containing brush-like polymer according to claim 1, characterized in that, The polymerization temperature is the applicable temperature for the free radical polymerization initiator, which is 0-100℃; the polymerization time is 1-48 hours.

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

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