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CN112094414B - Preparation method of novel liquid silicon carbide ceramic precursor - Google Patents

Preparation method of novel liquid silicon carbide ceramic precursor Download PDF

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CN112094414B
CN112094414B CN202011014945.0A CN202011014945A CN112094414B CN 112094414 B CN112094414 B CN 112094414B CN 202011014945 A CN202011014945 A CN 202011014945A CN 112094414 B CN112094414 B CN 112094414B
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silicon carbide
carbide ceramic
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顾喜双
周永江
郏保琪
曹义
张雄军
尚来东
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Ningbo Shuxiang New Material Co ltd
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    • C04B35/571—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide obtained from Si-containing polymer precursors or organosilicon monomers

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Abstract

The invention provides a preparation method of a novel liquid silicon carbide ceramic precursor, which comprises the following steps: by mixing liquid silane containing silicon hydrogen bond with liquid silane containing 1 or more2 CH2(ii) hydrosilylation of a CH-bonded silane containing 1 or 2 CH groups to obtain an intermediate product2CH-bonded silane having at least two Y groups bonded to the silicon atom, said Y groups being reducible to Si-H bonds, liquid silane containing Si-H bonds being reduced by the consumption of one Si-H bond by introducing at least one silane which is reducible to Si-H bonds as an intermediate product, the intermediate product being reduced to obtain a silane containing Si (-H)2And/or Si (-H)3The novel liquid silicon carbide ceramic precursor can be self-crosslinked, the silicon-hydrogen bond content of the novel liquid silicon carbide ceramic precursor which can be self-crosslinked is high, and the novel liquid silicon carbide ceramic precursor can be used as a raw material for preparing high-content heterogeneous element polycarbosilane.

Description

Preparation method of novel liquid silicon carbide ceramic precursor
Technical Field
The invention belongs to the field of silicon carbide ceramic precursors, and particularly relates to a preparation method of a novel liquid silicon carbide ceramic precursor.
Background
The polycarbosilane is used as a precursor of the silicon carbide ceramic material, and directly determines the performance of the silicon carbide ceramic material. At present, the industrialized polycarbosilane is obtained by pyrolysis of polydimethylsiloxane. However, the polycarbosilane prepared by the method has low silicon hydrogen content, the silicon hydrogen bond content is 0.7-0.8% measured by a chemical method, the theoretical content of the silicon hydrogen bond is 1.72%, and the actual measured value is far lower than the theoretical value (Song Maili, Friekun. SiC precursor-application research progress [ J ] of polycarbosilane, Chinese material progress, 2013, 032(004): 243-.
The root is to the end, in the process of high-temperature pyrolysis of the polydimethylsiloxane, firstly, the silicon-silicon bond is broken to form the liquid low-molecular-weight polysilane, and then the liquid low-molecular-weight polysilane is further subjected to rearrangement reaction to obtain the low-molecular-weight polysilane with Si-CH3、Si-CH2SiC of-Si, Si-H composition4、SiC3H, and the like, and further carrying out dehydrogenation and/or demethanization reaction between a silicon-hydrogen bond and a silicon methyl group between the low molecular weight liquid polycarbosilanes to obtain the polycarbosilane with a certain molecular weight. In the process, the obtained low-molecular-weight liquid polycarbosilane has low silicon hydrogen content and low activity, and the yield of the ceramic of the low-molecular-weight liquid polycarbosilane at 1000 ℃ is almost 0 percent by directly carrying out thermogravimetric analysis on the low-molecular-weight liquid polycarbosilane. In order to solve the problem of the ceramic yield of the low molecular weight liquid polycarbosilane at 1000 ℃, a lot of modification researches are carried out in China, for example, the low molecular weight liquid polycarbosilane and tetramethyl tetravinylcyclotetrasiloxane (D) are adopted4Vi), synthesizing Liquid Polycarbosilane (LPVCS), wherein the LPVCS has a crosslinking characteristic due to addition reaction of a silicon-hydrogen bond and a vinyl, so that the increase of molecular weight is realized, the volatilization of polycarbosilane molecules is prevented, and a certain ceramic yield is ensured. (Wang Yan bridge, Song Yongcai. vinyl-containing liquid polycarbosilane structure and performance representation [ J]An organic silicon material 2010(02) 20-23).
The existing research does not study how to increase the silicon-hydrogen bond content of the liquid polycarbosilane.
Disclosure of Invention
The invention aims to provide a preparation method of a novel liquid silicon carbide ceramic precursor, which uses liquid silane containing silicon hydrogen bonds and liquid silane containing 1 or 2 CH2(ii) hydrosilylation of a CH-bonded silane containing 1 or 2 CH groups to obtain an intermediate product2-CH-bonded silane having at least two Y attached to the silicon atom, said Y being selected from: at least one of ethoxy, methoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, Cl, Br and I, said Y being reducible to a silicon-hydrogen bond, the liquid silane containing a silicon-hydrogen bond introducing at least one silane reducible to a silicon-hydrogen bond as an intermediate product upon consumption of one silicon-hydrogen bond, and reducing the intermediate product to obtain a liquid silane containing Si (-H)2And/or Si (-H)3The novel liquid silicon carbide ceramic precursor can be self-crosslinked, and the novel liquid silicon carbide ceramic precursorThe ceramic precursor has high self-crosslinking silicon-hydrogen bond content, can be used as a raw material for preparing high-content heterogeneous element polycarbosilane, and can also be used as a raw material for synthesizing novel solid polycarbosilane.
The specific technical scheme is as follows: a preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 20-200 ℃, and the reaction time is 1-30 hours, so that the first intermediate product is prepared;
the mass ratio of the first raw material to the solvent is 1: 0-18;
the mass ratio of the first raw material to the second raw material is 1: 0.1-3.2;
the first raw material is liquid silane containing Si-H;
the molecular weight of the first raw material is 300-510, and the viscosity is 10-50 cp;
the second raw material contains (X) nSi (Y) m; x is CH2＝CH－A－、 CH2CH-, A is acyl, acyloxy, saturated alkane, phenyl, cyclic hydrocarbon; y is at least one of Cl, Br, I and alkoxy, the sum of n and m is equal to one of 3 and 4, n is one of 1 and 2, and m is one of 2 and 3;
the molecular weight of the second raw material is 144-450;
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding a reducing agent into the first intermediate product, reacting for 2-20 h at-20-120 ℃, and reducing the Y into a hydrogen atom to prepare a second intermediate product;
and 3, carrying out solid-liquid separation treatment on the second intermediate product to realize solid-liquid separation, and removing solids to obtain the novel liquid silicon carbide ceramic precursor.
Further, in the first step, the first raw material is liquid polycarbosilane and/or liquid polysilane containing a silicon-hydrogen bond, and the first raw material is prepared by cracking polydimethylsilane;
in the first step, the second raw material may be selected from one or more of the following compounds: vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri-n-propoxysilane, vinyltriisopropoxysilane, vinyltri-n-butoxysilane, vinyltriisobutoxysilane, vinyltri-tert-butoxysilane, methylvinyldiethoxysilane, methylvinyldimethoxysilane, methylvinyldi-n-propoxysilane, methylvinylmono-n-propoxysilane, methylvinyldiisopropoxysilane, phenylvinyldiethoxysilane, phenylvinyldimethoxysilane, phenylvinyldi-n-propoxysilane, vinylmonomethoxy-n-propoxysilane, vinyldimethoxymono-n-butoxysilane; vinyltrichlorosilane, vinyltriiodosilane, vinyltribromosilane, vinyldichloromonomethoxysilane, vinyldichloroethoxysilane, vinyldichloron-propoxysilane, vinyldichloroisopropoxysilane, vinyldichloromono-n-butoxysilane, vinyldichloromonoisobutoxysilane, vinylmonochlorodimethoxysilane, vinylmonochlorodiethoxysilane, vinylmonochlorodiisopropoxysilane, methylvinyldichlorosilane, methylvinylmonochloromethoxysilane, methylvinylmonochloroethoxysilane, methylvinylmonochloropropoxysilane, methylvinylmonochloroisopropoxoxysilane, methylvinylmonochloromonobutoxysilane, vinylmonochlorodioxysilane, vinylmonochlorodimethoxysilane, vinyldichlorosilane, vinylmethoxysilane, vinyldichlorosilane, vinyltriethoxysilane, and/or-and/or, Vinyl monochlorodiethoxysilane, vinyl monochlorodin-propoxysilane, vinyl monochlorodiisopropoxysilane, propenyl trichlorosilane, propenyl tribromosilane, propenyl triiodosilane, propenyl triethoxysilane, propenyl trimethoxysilane, propenyl tripropoxysilane, methyl propenyl diethoxysilane, methyl propenyl dimethoxysilane, methyl propenyl dipropoxysilane, phenyl propenyl diethoxysilane, phenyl propenyl dimethoxysilane, phenyl propenyl dipropoxysilane, propenyl monomethoxy-monoethoxy-monopropoxysilane; monovinyl-propenyl diethoxysilane, monovinyl-propenyl dimethoxysilane, monovinyl-propenyl dipropoxysilane, divinyldiethoxysilane, divinyldimethoxysilane, divinyldi-n-propoxysilane, divinyldiisopropoxysilane, divinyl di-n-butoxysilane, divinyl dichlorosilane, divinyl diiodosilane, divinyl dibromosilane, divinyl monochloromethoxysilane, divinyl monochloroethyloxysilane, divinyl monochloro-n-propoxysilane, divinyl monochloro-isopropoxysilane, divinyl monochloro-n-butoxysilane, divinyl monochloro-isobutoxysilane.
Further, in the second step, the reducing agent is at least one of lithium aluminum hydride, lithium hydride, magnesium hydride, sodium hydride and red aluminum.
Further, in the first step, the mass ratio of the first raw material to the solvent is 1:0.
Further, in the first step, the mass ratio of the first raw material to the solvent is 1: 0.1-1.0; the solvent is at least one of xylene, toluene and cyclohexane.
Furthermore, the molecular weight of the novel liquid silicon carbide ceramic precursor is 402-1540, and the viscosity is 15-1643 cp.
Furthermore, the content of silicon-hydrogen bonds of the novel liquid silicon carbide ceramic precursor is 0.34-1.40 mol/100g, and the novel liquid silicon carbide ceramic precursor can be dehydrogenated for self-crosslinking.
Further, after the novel liquid silicon carbide ceramic precursor is dehydrogenated and self-crosslinked, the ceramic yield at 1000 ℃ is higher than 20%.
Furthermore, the content of silicon-hydrogen bonds of the novel liquid silicon carbide ceramic precursor is 0.81-1.40 mol/100g, and the novel liquid silicon carbide ceramic precursor can be dehydrogenated and self-crosslinked.
Further, after the novel liquid silicon carbide ceramic precursor is dehydrogenated and self-crosslinked, the ceramic yield at 1000 ℃ is 70-90%.
The invention has the following beneficial effects:
1. by using liquid silane containing silicon hydrogen bond and liquid silane containing 1 or two CH2Hydrosilylation reaction of silanes containing 1 or two CH bonds to give an intermediate product2-CH-bonded silane having at least two Y attached to the silicon atom, said Y being selected from: at least one of ethoxy, methoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, Cl, Br and I, wherein Y can be reduced to a silicon hydrogen bond, and the liquid silane containing a silicon hydrogen bond introduces at least one silane which can be reduced to a silicon hydrogen bond as an intermediate product when one silicon hydrogen bond is consumed, and the intermediate product is reduced to obtain a liquid silane containing Si (-H)2And/or Si (-H)3The novel liquid silicon carbide ceramic precursor can be self-crosslinked, the silicon-hydrogen bond content of the novel liquid silicon carbide ceramic precursor which can be self-crosslinked is high, and the novel liquid silicon carbide ceramic precursor can be used as a raw material for preparing high-content heterogeneous element polycarbosilane.
2. The method does not need solvent or waste liquid, only solid waste is generated in the preparation process, and the mass ratio of the product to the solid waste is low and can be 0.014-0.9 of the product mass.
3. The amount of used solvent is small, and the waste liquid is small.
4. The product contains a large number of active groups and can be subjected to dehydrogenation addition.
5. By adopting the method, the silicon-hydrogen content of the novel liquid silicon carbide ceramic precursor can be regulated and controlled within the range of 0.34-1.40 mol/100g, and the silicon carbide ceramic precursor with different silicon-hydrogen contents can be obtained.
Drawings
Embodiments of the invention are described in further detail below with reference to the attached drawing figures, wherein:
FIG. 1 is an infrared spectrum of the feed and product of example two, where the feed is curve b and the product is curve a;
FIG. 2 is a thermogravimetric plot of the feedstock and product of example two, wherein the feedstock is plot b and the product is plot a;
FIG. 3 is a plot of the molecular weight distribution of the feed and product of example two, where the feed is plot b and the product is plot a;
FIG. 4 is a thermogravimetric plot of a portion of the product, wherein the thermogravimetric plot of the first product of example is 1, the thermogravimetric plot of the fourth product of example is 4, the thermogravimetric plot of the fifth product of example is 5, the thermogravimetric plot of the sixth product of example is 6, the thermogravimetric plot of the first product of example is seven, and the thermogravimetric plot of the first product of example is 7;
Detailed Description
The invention discloses a method for preparing a silicon-hydrogen bond-containing liquid silane by reacting a silicon-hydrogen bond-containing liquid silane with a compound containing 1 or two CH2Hydrosilylation reaction of silanes containing 1 or two CH bonds to give an intermediate product2-CH-bonded silane having at least two Y attached to the silicon atom, said Y being selected from: at least one of ethoxy, methoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, Cl, Br and I, said Y being reducible to a silicon-hydrogen bond, the liquid silane containing a silicon-hydrogen bond introducing at least one silane reducible to a silicon-hydrogen bond as an intermediate product upon consumption of one silicon-hydrogen bond, and reducing the intermediate product to obtain a liquid silane containing Si (-H)2And/or Si (-H)3The novel liquid silicon carbide ceramic precursor can be self-crosslinked, the silicon-hydrogen bond content of the novel liquid silicon carbide ceramic precursor which can be self-crosslinked is high, and the novel liquid silicon carbide ceramic precursor can be used as a raw material for preparing high-content heterogeneous element polycarbosilane.
The invention is further illustrated below with reference to examples one to twenty-one:
in the present specification, the hydrogen content is measured by nuclear magnetic hydrogen spectrometry, and an internal standard substance is added for quantitative analysis and measurement.
[ EXAMPLES one ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 20 ℃, the reaction time is 30 hours, so that the first intermediate product is prepared, and under the condition of normal pressure, the inert atmosphere is used for protection;
the mass ratio of the first raw material to the solvent is 1: 0;
the mass ratio of the first raw material to the second raw material is 1: 0.1;
the first raw material is 100g of liquid polycarbosilane containing Si-H (obtained by pyrolysis of polydimethylsiloxane, which can be referred to as a reference document: Wangqiao, Songyuancai. the structural and performance characteristics of the liquid polycarbosilane containing vinyl [ J ]. organosilicon material, 2010(02):20-23.), and the content of silicon-hydrogen bonds is 0.7mol/100 g;
the molecular weight of the first raw material is 450, and the viscosity is 30 cp;
the second raw material is vinyl triethoxysilane (commercially available);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 1.8g of reducing agent lithium aluminum hydride into the first intermediate product, reacting at-20 ℃ for 20 hours, and reducing ethoxy groups into hydrogen atoms to obtain a second intermediate product;
and 3, standing the second intermediate product for 4 hours to realize solid-liquid separation, and removing 8.75g of solids to prepare the novel liquid silicon carbide ceramic precursor.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 481, and the viscosity is 32 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.78mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor3The content is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1Liquid state polycarbon ofSilane, Si (H) in the novel liquid silicon carbide ceramic precursor3Can be dehydrogenated and crosslinked, and has the advantages of rapid growth of molecular weight and high ceramic yield.
[ example two ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 100 ℃, the protection is carried out in an inert atmosphere, and the reaction time is 10 hours, so that the first intermediate product is prepared;
the mass ratio of the first raw material to the second raw material is 1: 1.28;
the first raw material is 100g of liquid polycarbosilane containing Si-H (obtained by pyrolysis of polydimethylsiloxane, which can be referred to as a reference document: Wangqiao, Songyuancai. the structural and performance characteristics of the liquid polycarbosilane containing vinyl [ J ]. organosilicon material, 2010(02):20-23.), and the content of silicon-hydrogen bonds is 0.7mol/100 g;
the molecular weight of the first raw material is 510, and the viscosity is 32 cp;
the second raw material is vinyl trichlorosilane (sold in markets);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 27.11g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 5h at 80 ℃, and reducing silicon-chlorine bonds into silicon-hydrogen bonds to obtain a second intermediate product;
and 3, standing the second intermediate product for 10 hours to realize solid-liquid separation, and removing 109.13g of solids to obtain the novel liquid silicon carbide ceramic precursor.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 652, and the viscosity is 35 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 1.32mol/100 g.
The novel liquid silicon carbide ceramic precursor is at normal temperatureStable, no change in molecular weight and viscosity after 3 months of storage under normal temperature and sealing conditions, Si (H) in the novel liquid silicon carbide ceramic precursor3The content is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1The novel liquid silicon carbide ceramic precursor of Si (H)3Can be dehydrogenated and crosslinked, and has the advantages of rapid growth of molecular weight and high ceramic yield.
[ EXAMPLE III ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 200 ℃, the reaction time is 1h, so that the first intermediate product is prepared, and the reaction is carried out in a high-pressure kettle under the protection of inert atmosphere and the reaction pressure is 6 Mpa;
the mass ratio of the first raw material to the second raw material is 1: 0.54;
in the first step, the mass ratio of the first raw material to the solvent is 1: 1.0; the solvent is cyclohexane.
The first raw material is 100g of liquid polycarbosilane containing Si-H (a byproduct of polycarbosilane prepared by pyrolysis of polydimethylsiloxane), and the content of a silicon-hydrogen bond is 0.65mol/100 g;
the molecular weight of the first raw material is 320, and the viscosity is 20 cp;
the second starting material was divinyldichlorosilane (commercially available);
it is noted that, in this embodiment, the first raw material is dropped into the mixture of the second raw material and the solvent cyclohexane to control only one ethylene group in the divinyl dichlorosilane to perform hydrosilylation reaction, and the other ethylene group is remained;
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 8.72g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 2h at 120 ℃, and reducing silicon-chlorine bonds into silicon-hydrogen bonds to obtain a second intermediate product;
and 3, carrying out centrifugal treatment on the second intermediate product for 50s to realize solid-liquid separation, and removing 33.07g of solid to obtain the novel liquid silicon carbide ceramic precursor.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 532, and the viscosity is 90 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.77mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor2(CH＝CH2) The content of the groups is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1The novel liquid silicon carbide ceramic precursor can be dehydrogenatively crosslinked. Can be cross-linked by hydrosilylation, and has high ceramic yield.
[ EXAMPLE IV ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 140 ℃, the reaction time is 15 hours, so that the first intermediate product is prepared, the reaction is carried out in a high-pressure kettle under the protection of inert atmosphere, and the reaction pressure is 8 Mpa;
the mass ratio of the first raw material to the second raw material is 1: 0.44;
in the first step, the mass ratio of the first raw material to the solvent is 1: 1; the solvent is toluene.
The first raw material is 100g of liquid polysilane containing Si-H (intermediate product of polycarbosilane prepared by pyrolysis of polydimethylsiloxane, main chain is silicon-silicon bond), and the content of silicon-hydrogen bond is 0.45mol/100 g;
the molecular weight of the first raw material is 320, and the viscosity is 10 cp;
the second raw material is propenyl trichlorosilane (sold in the market);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 13.58g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 3h at 80 ℃, and reducing silicon-chlorine bonds into silicon-hydrogen bonds to obtain a second intermediate product;
and 3, carrying out ultrasonic treatment on the second intermediate product for 6000s to realize solid-liquid separation, removing 39.53g of solid, and removing the solvent toluene under reduced pressure to obtain the novel liquid silane.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 423, and the viscosity is 16 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.81mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor3The content is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1The novel liquid silicon carbide ceramic precursor of Si (H)3Can be dehydrogenated and crosslinked, and has the advantages of rapid growth of molecular weight and high ceramic yield.
[ EXAMPLE V ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 200 ℃, the reaction time is 1h, so that the first intermediate product is prepared, and the reaction is carried out in a high-pressure kettle under the protection of inert atmosphere and the reaction pressure is 16 Mpa;
the mass ratio of the first raw material to the second raw material is 1: 0.18;
the first raw material is 100g of liquid polysilane containing Si-H (intermediate product of polycarbosilane prepared by pyrolysis of polydimethylsiloxane, main chain is silicon-silicon bond), and the content of silicon-hydrogen bond is 0.45mol/100 g;
the molecular weight of the first raw material is 300, and the viscosity is 10 cp;
the second raw material is propenyl trichlorosilane (sold in the market);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 4.68g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 20 hours at the temperature of minus 20 ℃, and reducing silicon-chlorine bonds into silicon-hydrogen bonds to prepare a second intermediate product;
and 3, carrying out ultrasonic treatment on the second intermediate product for 30s to realize solid-liquid separation, and removing 15.29g of solids to obtain the novel liquid silane.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 402, and the viscosity is 15 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.61mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor3The content is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1The novel liquid silicon carbide ceramic precursor of Si (H)3Can be dehydrogenated and crosslinked, and has the advantages of rapid growth of molecular weight and high ceramic yield.
[ EXAMPLE six ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 80 ℃, the reaction time is 20 hours, so that the first intermediate product is prepared, and the reaction process and the protection of inert atmosphere are carried out;
the mass ratio of the first raw material to the second raw material is 1: 0.79;
the first raw material is 100g of liquid polysilane containing Si-H (intermediate product of polycarbosilane prepared by pyrolysis of polydimethylsiloxane, main chain is silicon-silicon bond), and the content of silicon-hydrogen bond is 0.45mol/100 g;
the molecular weight of the first raw material is 300, and the viscosity is 10 cp;
the second raw material is propenyl trichlorosilane (sold in the market);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 21.80g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 2h at 80 ℃, and reducing silicon-chlorine bonds into silicon-hydrogen bonds to obtain a second intermediate product;
and 3, centrifuging the second intermediate product for 10s to realize solid-liquid separation, and removing 68.38g of solids to obtain the novel liquid silane.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 489, and the viscosity is 17 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 1.02mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor3The content is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1The novel liquid silicon carbide ceramic precursor of Si (H)3Can be dehydrogenated and crosslinked, and has the advantages of rapid growth of molecular weight and high ceramic yield.
[ EXAMPLE VII ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 20 ℃, the reaction time is 30 hours, so that the first intermediate product is prepared, and the reaction process and the protection of inert atmosphere are carried out;
the mass ratio of the first raw material to the second raw material is 1: 0.53;
in the first step, the mass ratio of the first raw material to the solvent xylene is 1: 0.6; the solvent is toluene.
The first raw material is 100g of liquid polysilane containing Si-H (intermediate product of polycarbosilane prepared by pyrolysis of polydimethylsiloxane, main chain is silicon-silicon bond), and the content of silicon-hydrogen bond is 0.45mol/100 g;
the molecular weight of the first raw material is 430, and the viscosity is 11 cp;
the second raw material is propenyl trichlorosilane (sold in the market);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 15.49g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 15h at 60 ℃, and reducing silicon-chlorine bonds into silicon-hydrogen bonds to obtain a second intermediate product;
and 3, centrifuging the second intermediate product for 100s to realize solid-liquid separation and remove 46.75g of solids, thereby preparing the solution of the novel liquid silane.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 512, and the viscosity is 34 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.87mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor3The content is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1The novel liquid silicon carbide ceramic precursor of Si (H)3Can be dehydrogenated and crosslinked, and has the advantages of rapid growth of molecular weight and high ceramic yield.
[ example eight ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 100 ℃, the reaction time is 15 hours, so that the first intermediate product is prepared, and the reaction process and the protection of inert atmosphere are carried out;
the mass ratio of the first raw material to the second raw material is 1: 0.61;
in the first step, the mass ratio of the first raw material to the solvent xylene is 1: 0.8; the solvent is toluene.
The first raw material is a mixture of 50g of liquid polycarbosilane (intermediate product of polycarbosilane prepared by pyrolyzing polydimethysilane, and the main chain is a silicon-silicon bond) with the silicon-hydrogen bond content of 0.45mol/100g and 50g of liquid polycarbosilane (byproduct of polycarbosilane prepared by pyrolyzing polydimethysilane);
the molecular weight of the first raw material is 320, and the viscosity is 20 cp;
the second raw material is propenyl trichlorosilane (sold in the market);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 10.90g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 6h at 74 ℃, and reducing silicon-chlorine bonds into silicon-hydrogen bonds to obtain a second intermediate product;
and 3, carrying out centrifugal treatment on the second intermediate product for 4000s to realize solid-liquid separation, and removing 46.87g of solid to prepare the solution of the novel liquid silane.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 561, and the viscosity is 71 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 1.00mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor3The content is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1The novel liquid silicon carbide ceramic precursor of Si (H)3Can be dehydrogenated and crosslinked, and has the advantages of rapid growth of molecular weight and high ceramic yield.
[ EXAMPLE ninth ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 150 ℃, the reaction time is 13 hours, so that the first intermediate product is prepared, and the reaction process and the protection of inert atmosphere are carried out;
the mass ratio of the first raw material to the second raw material is 1: 0.26;
the first raw material is a mixture of 20g of liquid polycarbosilane (intermediate product of polycarbosilane prepared by pyrolyzing polydimethysilane, and the main chain is silicon-silicon bond) with the silicon-hydrogen bond content of 0.45mol/100g and 80g of liquid polycarbosilane (byproduct of polycarbosilane prepared by pyrolyzing polydimethysilane);
the molecular weight of the first raw material is 320, and the viscosity is 20 cp;
the second raw material is propenyl trichlorosilane (sold in the market);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 5.49g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 15h at 55 ℃, and reducing silicon-chlorine bonds into silicon-hydrogen bonds to prepare a second intermediate product;
and 3, carrying out centrifugal treatment on the second intermediate product for 2000s to realize solid-liquid separation, and removing 20.82g of solid to prepare the novel liquid silane.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 549, and the viscosity is 74 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.82mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor3The content is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1The novel liquid silicon carbide ceramic precursor of Si (H)3Can be dehydrogenated and crosslinked, and has the advantages of rapid growth of molecular weight and high ceramic yield.
[ EXAMPLE eleven ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 20 ℃, the reaction time is 24 hours, so that the first intermediate product is prepared, and the reaction process and the protection of inert atmosphere are carried out;
the mass ratio of the first raw material to the second raw material is 1: 0.1;
the mass ratio of the first raw material to the solvent cyclohexane is 1: 0.90;
the first raw material is a mixture of 100g of liquid polycarbosilane (a product of pyrolysis of polydimethylsiloxane), and the content of silicon-hydrogen bonds is 0.7mol/100 g;
the molecular weight of the first raw material is 450, and the viscosity is 30 cp;
the second starting material was divinyldichlorosilane (commercially available);
it is noted that, in this embodiment, the first raw material is dropped into the mixture of the second raw material and the solvent cyclohexane to control only one ethylene group in the divinyl dichlorosilane to perform hydrosilylation reaction, and the other ethylene group is remained;
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 1.49g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 15h at 55 ℃, and reducing silicon-chlorine bonds into silicon-hydrogen bonds to prepare a second intermediate product;
and 3, carrying out ultrasonic treatment on the second intermediate product for 3000s to realize solid-liquid separation, and removing 6.0g of solid to prepare the solution of the novel liquid silane.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 949, and the viscosity is 1154 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.73mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor2(CH＝CH2) The content of the groups is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1The novel liquid silicon carbide ceramic precursor can be dehydrogenatively crosslinked. Can be cross-linked by hydrosilylation, and has high ceramic yield.
[ example eleven ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 58 ℃, the reaction time is 24 hours, so that the first intermediate product is prepared, and the reaction process and the protection of inert atmosphere are carried out;
the mass ratio of the first raw material to the second raw material is 1: 0.6;
the mass ratio of the first raw material to the solvent cyclohexane is 1: 0.60;
the first raw material is a mixture of 100g of liquid polycarbosilane (a product of pyrolysis of polydimethylsiloxane), and the content of silicon-hydrogen bonds is 0.7mol/100 g;
the molecular weight of the first raw material is 450, and the viscosity is 30 cp;
the second starting material was divinyldichlorosilane (commercially available);
it is noted that, in this embodiment, the first raw material is dropped into the mixture of the second raw material and the solvent cyclohexane to control only one ethylene group in the divinyl dichlorosilane to perform hydrosilylation reaction, and the other ethylene group is remained;
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 8.94g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 13h at 55 ℃, and reducing silicon-chlorine bonds into silicon-hydrogen bonds to prepare a second intermediate product;
and 3, carrying out ultrasonic treatment on the second intermediate product for 3000s to realize solid-liquid separation, and removing 36.0g of solid to prepare the solution of the novel liquid silane.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 1149, and the viscosity is 1474 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.82mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor2(CH＝CH2) The content of the groups is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1The novel liquid silicon carbide ceramic precursor can be dehydrogenatively crosslinked. Can be cross-linked by hydrosilylation, and has high ceramic yield.
[ EXAMPLE twelfth ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 200 ℃, the reaction time is 30 hours, so that the first intermediate product is prepared, the reaction is carried out in a high-pressure kettle, the reaction pressure is 12Mpa, and the protection is carried out in an inert atmosphere;
the mass ratio of the first raw material to the solvent is 1: 0;
the mass ratio of the first raw material to the second raw material is 1: 0.35;
the first raw material is 100g of liquid polysilane containing Si-H (intermediate product of polycarbosilane prepared by pyrolysis of polydimethylsiloxane, main chain is silicon-silicon bond), and the content of silicon-hydrogen bond is 0.45mol/100 g;
the molecular weight of the first raw material is 320, and the viscosity is 10 cp;
the second starting material was divinyldichlorosilane (commercially available);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 5.22g of reducing agent lithium aluminum hydride into the first intermediate product, reacting at-20 ℃ for 20 hours, and reducing silicon-chlorine bonds into hydrogen atoms to obtain a second intermediate product;
and 3, carrying out ultrasonic treatment on the second intermediate product for 500s, standing for 3h to realize solid-liquid separation, and removing 21.00g of solid to prepare the novel liquid silicon carbide ceramic precursor.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 1540, and the viscosity is 1643 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.38mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor2Relative to Si (H) in the hyperbranched liquid polycarbosilane3Higher stability, the novel liquid silicon carbide ceramicThe precursor will not self-polymerize at normal temperature, compared with the precursor containing only Si (H)1The novel liquid silicon carbide ceramic precursor can be dehydrogenated and crosslinked, the molecular weight can grow up quickly, and the ceramic yield is high.
[ EXAMPLE thirteen ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 200 ℃, the reaction time is 25 hours, so that the first intermediate product is prepared, the reaction is carried out in a high-pressure kettle, the reaction pressure is 20Mpa, and the protection is carried out in an inert atmosphere;
the mass ratio of the first raw material to the cyclohexane solvent is 1: 2;
the mass ratio of the first raw material to the second raw material is 1: 0.2;
the first raw material is 100g of liquid polysilane containing Si-H (intermediate product of polycarbosilane prepared by pyrolysis of polydimethylsiloxane, main chain is silicon-silicon bond), and the content of silicon-hydrogen bond is 0.45mol/100 g;
the molecular weight of the first raw material is 320, and the viscosity is 10 cp;
the second starting material was divinyldichlorosilane (commercially available);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 2.98g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 20 hours at-3 ℃, and reducing silicon-chlorine bonds into hydrogen atoms to obtain a second intermediate product;
and 3, carrying out ultrasonic treatment on the second intermediate product for 800s, standing for 5h to realize solid-liquid separation, and removing 12.00g of solid to prepare the cyclohexane solution of the novel liquid silicon carbide ceramic precursor.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 1246, and the viscosity is 1400 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.4mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor2Relative to Si (H) in the hyperbranched liquid polycarbosilane3The stability is higher, the novel liquid silicon carbide ceramic precursor can not self-polymerize at normal temperature, and compared with the precursor only containing Si (H)1The novel liquid silicon carbide ceramic precursor can be dehydrogenated and crosslinked, the molecular weight can grow up quickly, and the ceramic yield is high.
[ example fourteen ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 140 ℃, the reaction time is 25 hours, so that the first intermediate product is prepared, the reaction is carried out in a high-pressure kettle, the reaction pressure is 12Mpa, and the protection is carried out in an inert atmosphere;
the mass ratio of the first raw material to the toluene solvent is 1: 18;
the mass ratio of the first raw material to the second raw material is 1: 0.3;
the first raw material is a mixture of 100g of liquid polycarbosilane (a product of pyrolysis of polydimethylsiloxane), and the content of silicon-hydrogen bonds is 0.7mol/100 g;
the molecular weight of the first raw material is 450, and the viscosity is 30 cp;
the second starting material was divinyldichlorosilane (commercially available);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 4.47g of reducing agent lithium aluminum hydride into the first intermediate product, reacting at 28 ℃ for 30 hours, and reducing silicon-chlorine bonds into hydrogen atoms to obtain a second intermediate product;
and 3, carrying out ultrasonic treatment on the second intermediate product for 3000s, standing for 5h to realize solid-liquid separation, and removing 18.00g of solid to prepare the toluene solution of the novel liquid silicon carbide ceramic precursor.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 1118, and the viscosity is 1224 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.6mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor2Relative to Si (H) in the hyperbranched liquid polycarbosilane3The stability is higher, the novel liquid silicon carbide ceramic precursor can not self-polymerize at normal temperature, and compared with the precursor only containing Si (H)1The novel liquid silicon carbide ceramic precursor can be dehydrogenated and crosslinked, the molecular weight can grow up quickly, and the ceramic yield is high.
[ example fifteen ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 195 ℃, the reaction time is 29 hours, so that the first intermediate product is prepared, the reaction is carried out in a high-pressure kettle, the reaction pressure is 13Mpa, and the protection is carried out in an inert atmosphere;
the mass ratio of the first raw material to the solvent is 1: 0;
the mass ratio of the first raw material to the second raw material is 1: 0.35;
the first raw material is a mixture of 100g of liquid polycarbosilane (a byproduct of pyrolysis of polycarbosilane by polydimethylsiloxane), and the content of a silicon-hydrogen bond is 0.65mol/100 g;
the molecular weight of the first raw material is 320, and the viscosity is 20 cp;
the second starting material was divinyldichlorosilane (commercially available);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 5.22g of reducing agent lithium aluminum hydride into the first intermediate product, reacting at 28 ℃ for 30h, and reducing silicon-chlorine bonds into hydrogen atoms to obtain a second intermediate product;
and 3, carrying out ultrasonic treatment on the second intermediate product for 3000s, standing for 5h to realize solid-liquid separation, and removing 21.00g of solid to prepare the novel liquid silicon carbide ceramic precursor.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 1189, and the viscosity is 1500 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.54 mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor2Relative to Si (H) in the hyperbranched liquid polycarbosilane3The stability is higher, the novel liquid silicon carbide ceramic precursor can not self-polymerize at normal temperature, and compared with the precursor only containing Si (H)1The novel liquid silicon carbide ceramic precursor can be dehydrogenated and crosslinked, the molecular weight can grow up quickly, and the ceramic yield is high.
[ example sixteen ] to
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 180 ℃, the reaction time is 20 hours, so that the first intermediate product is prepared, the reaction is carried out in a high-pressure kettle, the reaction pressure is 13Mpa, and the inert atmosphere is protected;
the mass ratio of the first raw material to the solvent is 1: 0;
the mass ratio of the first raw material to the second raw material is 1: 0.2;
the first raw material is a mixture of 100g of liquid polycarbosilane (a byproduct of pyrolysis of polycarbosilane by polydimethylsiloxane), and the content of a silicon-hydrogen bond is 0.65mol/100 g;
the molecular weight of the first raw material is 320, and the viscosity is 20 cp;
the second starting material was divinyldichlorosilane (commercially available);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 2.98g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 10 hours at 51 ℃, and reducing silicon-chlorine bonds into hydrogen atoms to prepare a second intermediate product;
and 3, carrying out ultrasonic treatment on the second intermediate product for 6000s, standing for 1h to realize solid-liquid separation, and removing 12.00g of solid to prepare the novel liquid silicon carbide ceramic precursor.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 842, and the viscosity is 1312 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.58mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor2Relative to Si (H) in the hyperbranched liquid polycarbosilane3The stability is higher, the novel liquid silicon carbide ceramic precursor can not self-polymerize at normal temperature, and compared with the precursor only containing Si (H)1The novel liquid silicon carbide ceramic precursor can be dehydrogenated and crosslinked, the molecular weight can grow up quickly, and the ceramic yield is high.
[ example seventeen ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 160 ℃, the reaction time is 10 hours, so that the first intermediate product is prepared, the reaction is carried out in a high-pressure kettle, the reaction pressure is 19Mpa, and the inert atmosphere is protected;
the mass ratio of the first raw material to the solvent cyclohexane is 1: 8;
the mass ratio of the first raw material to the second raw material is 1: 0.5;
the first raw material is a mixture of 100g of liquid polycarbosilane (a byproduct of pyrolysis of polycarbosilane by polydimethylsiloxane), and the content of a silicon-hydrogen bond is 0.65mol/100 g;
the molecular weight of the first raw material is 320, and the viscosity is 20 cp;
the second starting material was divinyldichlorosilane (commercially available);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 7.45g of reducing agent lithium aluminum hydride into the first intermediate product, reacting at 66 ℃ for 18h, and reducing silicon-chlorine bonds into hydrogen atoms to obtain a second intermediate product;
and 3, standing the second intermediate product for 10 hours to realize solid-liquid separation, and removing 30.00g of solids to prepare the cyclohexane solution of the novel liquid silicon carbide ceramic precursor.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 1265, and the viscosity is 1860 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.51mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, the molecular weight and the viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the sealed condition at normal temperature, and Si (H) in the novel liquid silicon carbide ceramic precursor2Relative to Si (H) in the hyperbranched liquid polycarbosilane3The stability is higher, the novel liquid silicon carbide ceramic precursor can not self-polymerize at normal temperature, and compared with the precursor only containing Si (H)1The novel liquid silicon carbide ceramic precursor can be dehydrogenated and crosslinked, the molecular weight can be rapidly increased, and the liquid polycarbosilane has high ceramic yieldAnd (4) rate.
[ EXAMPLE eighteen ]
A preparation method of a novel liquid silicon carbide ceramic precursor comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 160 ℃, the reaction time is 10 hours, so that the first intermediate product is prepared, the reaction is carried out in a high-pressure kettle, the reaction pressure is 19Mpa, and the inert atmosphere is protected;
the mass ratio of the first raw material to the solvent cyclohexane is 1: 8;
the mass ratio of the first raw material to the second raw material is 1: 1.48;
the first raw material is a mixture of 100g of liquid polycarbosilane (a byproduct of pyrolysis of polycarbosilane by polydimethylsiloxane), and the content of a silicon-hydrogen bond is 0.7mol/100 g;
the molecular weight of the first raw material is 320, and the viscosity is 20 cp;
the second raw material is propenyl trichlorosilane (sold in the market);
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding 43.26g of reducing agent lithium aluminum hydride into the first intermediate product, reacting for 18h at 66 ℃ to reduce silicon-chlorine bonds into hydrogen atoms, thereby preparing a second intermediate product;
and 3, standing the second intermediate product for 10 hours to realize solid-liquid separation, and removing 130.54g of solids to prepare the cyclohexane solution of the novel liquid silicon carbide ceramic precursor.
The molecular weight of the novel liquid silicon carbide ceramic precursor is 1400, and the viscosity is 1532 cp.
The content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 1.40mol/100 g.
The novel liquid silicon carbide ceramic precursor is stable at normal temperature, and the molecular weight and viscosity are not changed after the novel liquid silicon carbide ceramic precursor is stored for 3 months under the closed condition at normal temperature, and the novel liquid silicon carbide ceramic precursor is prepared by the methodSi (H) in silicon ceramic precursor3The content is much lower than that of hyperbranched liquid polycarbosilane, the stability is higher than that of the hyperbranched liquid polycarbosilane containing only Si (H)1The novel liquid silicon carbide ceramic precursor of Si (H)3Can be dehydrogenated and crosslinked, and has the advantages of rapid growth of molecular weight and high ceramic yield.
[ example nineteen ]
After the novel liquid silicon carbide ceramic precursor obtained in example 2 was subjected to heat preservation at 100 ℃ for 10 hours in an inert atmosphere, the silicon-hydrogen bond content of the novel liquid silicon carbide ceramic precursor was 1.1mol/100g, and solid polycarbosilane having a softening point of 80 ℃ was obtained.
[ example twenty ]
After the novel liquid silicon carbide ceramic precursor obtained in example 2 was subjected to heat preservation at 110 ℃ for 6 hours in an inert atmosphere, the content of silicon-hydrogen bonds of the novel liquid silicon carbide ceramic precursor was 1.0mol/100g, and solid polycarbosilane having a softening point of 110 ℃ was obtained.
[ example twenty-one ]
After the novel liquid silicon carbide ceramic precursor obtained in example 2 was subjected to heat preservation at 140 ℃ for 1 hour in an inert atmosphere, the content of silicon-hydrogen bonds of the novel liquid silicon carbide ceramic precursor was 0.8mol/100g, and solid polycarbosilane having a softening point of 190 ℃ was obtained.

Claims (9)

1. A preparation method of a novel liquid silicon carbide ceramic precursor is characterized by comprising the following steps: the method comprises the following steps:
step 1, synthesizing a first intermediate product;
carrying out hydrosilylation on a first raw material and a second raw material to obtain a first intermediate product;
the hydrosilylation reaction temperature is 20-200 ℃, and the reaction time is 1-30 hours, so that the first intermediate product is prepared;
the mass ratio of the first raw material to the solvent is 1: 0-18;
the mass ratio of the first raw material to the second raw material is 1: 0.1-3.2;
the first raw material is liquid polycarbosilane and/or liquid polysilane containing a silicon-hydrogen bond, and the first raw material is prepared by cracking polydimethylsiloxane;
the molecular weight of the first raw material is 300-510, and the viscosity is 10-50 cp;
the second raw material contains (X) nSi (Y) m; x is CH2Is CH-A-or CH2CH-, A is acyl, acyloxy, saturated alkane, phenyl, cyclic hydrocarbon; y is at least one of Cl, Br, I and alkoxy, the sum of n and m is equal to one of 3 and 4, n is one of 1 and 2, and m is one of 2 and 3;
the molecular weight of the second raw material is 144-450;
step 2, reducing the first intermediate product to prepare a second intermediate product;
adding a reducing agent into the first intermediate product, reacting for 2-20 h at-20-120 ℃, and reducing the Y into a hydrogen atom to prepare a second intermediate product;
and 3, carrying out solid-liquid separation treatment on the second intermediate product to remove solids, thereby preparing the novel liquid silicon carbide ceramic precursor.
2. The method for preparing a novel liquid silicon carbide ceramic precursor as claimed in claim 1, wherein:
in the first step, the second raw material may be selected from one or more of the following compounds: vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri-n-propoxysilane, vinyltriisopropoxysilane, vinyltri-n-butoxysilane, vinyltriisobutoxysilane, vinyltri-t-butoxysilane, methylvinyldiethoxysilane, methylvinyldimethoxysilane, methylvinyldi-n-propoxysilane, methylvinylmono-n-propoxysilane, methylvinyldiisopropoxysilane, phenylvinyldiethoxysilane, phenylvinyldimethoxysilane, phenylvinyldi-n-propoxysilane, vinylmonomethoxy-n-propoxysilane, vinyldimethoxymono-n-butoxysilane; vinyltrichlorosilane, vinyltriiodosilane, vinyltribromosilane, vinyldichloromonomethoxysilane, vinyldichloroethoxysilane, vinyldichloron-propoxysilane, vinyldichloroisopropoxysilane, vinyldichloron-butoxysilane, vinyldichloroisobutoxysilane, vinylmonochlorodimethoxysilane, vinylmonochlorodiethoxysilane, methylvinylmonochlorodiethoxysilane, methylvinylmonochloropropoxysilane, methylvinylmonochlorodiethoxysilane, methylvinylmonochloropropoxoxysilane, methylvinylmonochlorodiethoxysilane, vinylmonochlorodiethoxysilane, vinyldichloroethoxysilane, vinylmonochlorodiethoxysilane, vinyldichloroethoxysilane, vinylethoxysilane, vinyldichloroethoxysilane, vinylethoxysilane, vinylethoxy, Vinyl-monochlorodin-propoxysilane, vinyl-monochlorodiiso-propoxysilane, divinyl-diethoxysilane, divinyl-dimethoxysilane, divinyl-di-n-propoxysilane, divinyl-diisopropoxysilane, divinyl-di-n-butoxysilane, divinyl-dichlorosilane, divinyl-diiodosilane, divinyl-dibromosilane, divinyl-monochloromonethoxysilane, divinyl-monochloromonomethoxysilane, divinyl-monochloro-n-propoxysilane, divinyl-monochloroisopropoxysilane, divinyl-monochloro-n-butoxysilane, divinyl-monochloromonoisutoxysilane.
3. The method for preparing a novel liquid silicon carbide ceramic precursor as claimed in claim 1, wherein: in the second step, the reducing agent is at least one of lithium aluminum hydride, lithium hydride, magnesium hydride, sodium hydride and red aluminum.
4. The method for preparing a novel liquid silicon carbide ceramic precursor as claimed in claim 1, wherein: in the first step, the mass ratio of the first raw material to the solvent is 1: 0.1-1.0; the solvent is at least one of xylene, toluene and cyclohexane.
5. The method for preparing a novel liquid silicon carbide ceramic precursor as claimed in any one of claims 1 to 4, wherein: the molecular weight of the novel liquid silicon carbide ceramic precursor is 402-1540, and the viscosity is 15-1643 cp.
6. The method for preparing a novel liquid silicon carbide ceramic precursor as claimed in claim 5, wherein: the content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.34-1.40 mol/100 g.
7. The method for preparing a novel liquid silicon carbide ceramic precursor as claimed in claim 6, wherein: after the novel liquid silicon carbide ceramic precursor is dehydrogenated and self-crosslinked, the ceramic yield at 1000 ℃ is higher than 20%.
8. The method for preparing a novel liquid silicon carbide ceramic precursor as claimed in claim 7, wherein: the content of the silicon-hydrogen bond of the novel liquid silicon carbide ceramic precursor is 0.81-1.40 mol/100 g.
9. The method for preparing a novel liquid silicon carbide ceramic precursor as claimed in claim 8, wherein: after the novel liquid silicon carbide ceramic precursor is dehydrogenated and self-crosslinked, the ceramic yield at 1000 ℃ is 70-90%.
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