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Method for synthesizing high-ceramic-yield polycarbosilane

A polycarbosilane and synthesis method technology, applied in the field of organic silicon polymer synthesis, can solve the problems of high manufacturing cost, strong reactivity, harsh use conditions, etc., and achieve easy control of reaction conditions, easy mass production, and easy regulation Effect

Active Publication Date: 2015-07-01
NAT UNIV OF DEFENSE TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Due to its excellent performance, hyperbranched liquid polycarbosilane AHPCS has two major defects: (1) There are too many active Si-H in the structure of AHPCS, and the reactivity is too strong, making it difficult to guarantee storage stability. Harsh; (2) The synthesis process is complicated, the manufacturing cost is high, and it is difficult to prepare and use in large quantities

Method used

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  • Method for synthesizing high-ceramic-yield polycarbosilane
  • Method for synthesizing high-ceramic-yield polycarbosilane
  • Method for synthesizing high-ceramic-yield polycarbosilane

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Example 1 After mixing 1000 grams of polycarbosilane with a molecular weight of 500 and 120 grams of 3-bromopropene, place it in a reaction vessel, add 1000 mL of xylene, add 120 grams of n-butyllithium, and heat up to 130°C, and keep it warm for 3 hours. After the reaction was finished, the insoluble matter was removed by filtration, and the solvent was evaporated to obtain 1000 grams of polycarbosilane with a high ceramic yield.

[0021] Its infrared spectrum and thermogravimetric curve are as follows: figure 1 and image 3 as shown, figure 2 It is the thermogravimetric curve of low molecular weight polycarbosilane.

[0022] Depend on figure 1 It can be seen that the precursor structure contains Si-C, Si-CH 3 and other chemical bonds.

[0023] Depend on figure 2 It can be seen that the weight loss of low-molecular-weight polycarbosilane is 45% under the nitrogen condition of 1000°C, and the ceramic yield is 55%.

[0024] Depend on image 3 It can be seen th...

Embodiment 2

[0026] After mixing 1000 grams of polycarbosilane with a molecular weight of 1330 and 60 grams of 3-chloropropene, put it in a reaction vessel, add 1000 mL of xylene, add 60 grams of tert-butyllithium, and raise the temperature to 150 ° C under the protection of high-purity nitrogen. And keep warm for 5 hours. After the reaction was finished, the insolubles were removed by filtration, and the solvent was evaporated to obtain 992 grams of polycarbosilane with a high ceramic yield.

Embodiment 3

[0028] After mixing 1000 grams of polycarbosilane with a molecular weight of 1100 and 76 grams of 3-bromopropene, put it in a reaction vessel, add 1000 mL of xylene, add 76 grams of isobutyllithium, and raise the temperature to 100 ° C under the protection of high-purity nitrogen. And heat preservation reaction 8 hours. After the reaction was finished, the insoluble matter was removed by filtration, and the solvent was evaporated to obtain 1020 grams of polycarbosilane with a high ceramic yield.

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Abstract

The invention discloses a method for synthesizing high-ceramic-yield polycarbosilane. The method comprises the following steps: mixing polycarbosilane of which the molecular weight is 500-1,500 with an allyl compound according to the proportion 100:(12-4); dissolving the mixture into dimethylbenzene; putting into a reaction vessel; adding an organic lithium reagent; heating under the protection of protection gas for reacting; controlling the highest reaction temperature at 100-150 DEG C; preserving heat for reacting for 2-8 hours; after finishing the reaction, filtering insoluble substances; removing a solvent by evaporating to obtain the high-ceramic-yield polycarbosilane. The method has the characteristics of easiness in controlling of the reaction conditions, simple and convenient steps, self-crosslinking performance of a product, and adjustable Si-H and allyl content. The method can be used for preparing liquid-state or solid-state high-ceramic-yield polycarbosilane conveniently.

Description

technical field [0001] The invention belongs to the synthesis of organosilicon polymers, in particular to a synthesis method for preparing polycarbosilane with high ceramic yield, the precursor of silicon carbide ceramics and ceramic matrix composite materials. Background technique [0002] At present, polycarbosilane (polycarbosilane, PCS) is an organic polymer with Si-C as the main chain, and the basic structural unit is mainly SiC 3 H and SiC 4 , solid at room temperature, good stability, soluble in organic solvents such as toluene and xylene, and the ceramic yield rate after pyrolysis at 1000°C is 50-60%, and it is the most important silicon carbide (silicon carbide, SiC) ceramics pioneer Polycarbosilane is mainly synthesized by pyrolytic rearrangement of polydimethylsilane. The polycarbosilane produced by this method is the main raw material of continuous SiC fiber (Song Yongcai, Chinese invention patent, 201010300539.0, a kind of PCS fiber prepared method for continu...

Claims

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Application Information

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IPC IPC(8): C08G77/60
Inventor 邵长伟王军王浩简科谢征芳王小宙苟燕子
Owner NAT UNIV OF DEFENSE TECH
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