Catalytic rearrangement preparation method of polycarbosilane

A technology of polycarbosilane and carbosilane, which is applied in the field of catalytic synthesis of polycarbosilane, can solve the problems of lower production cost, low reaction temperature, and good product quality, and achieve high ceramic yield, high reaction rate, and guaranteed product quality Effect

Active Publication Date: 2016-01-27
INST OF CHEM CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] To sum up, in the existing methods for preparing polycarbosilane by pyrolysis and rearrangement, it is difficult to achieve short reaction time, high yield, low reaction temperature and good product quality at the same time, whether it is the normal pressure method or the high pressure method. Thereby significantly reducing the cost of preparation

Method used

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  • Catalytic rearrangement preparation method of polycarbosilane
  • Catalytic rearrangement preparation method of polycarbosilane
  • Catalytic rearrangement preparation method of polycarbosilane

Examples

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preparation example 1

[0047] Preparation example 1 (preparation of raw material LPS)

[0048] Add 1200g of solid PDMS powder into a 3L three-necked flask, vacuumize nitrogen or argon to replace the air three times, protect the argon flow, heat to 390-420°C with an electric heating mantle, and pyrolyze and distill to obtain about 1080g of colorless and transparent liquid silane (LPS), which 1 H-NMR, 29 Si-NMR, GC-MS and FTIR were as Figure 1-3 and Figure 10 (a) shown. These characterization results show that LPS is a complex mixture composed of more than 20 silane-carbosilane rings and a small number of linear small molecules, and its molecular structure can be determined by [(SiMe 2 ) 0.7 (CH 2 SiMeH) 0.3 ]express.

Embodiment 1

[0055] Experimental steps: (1) Vacuumize the atmospheric cracking rearrangement synthesis system, replace high-purity nitrogen, repeat 3 times; (2) under the protection of high-purity nitrogen, put the LPS (190g) of Preparation Example 1 into the reaction device In, then under stirring, add 0.38g of B (C 6 f 5 ) 3 Catalyst (being 0.20wt% of LPS); (3) heating up, be warming up to 395 ℃ through 35h, and heat preservation reaction 5h, total reaction time is 40h; (6) cooling room temperature obtains crude product 131.89g, and crude product liter To 370°C, low molecular weight was removed by distillation; (7) cooled to room temperature to obtain 122.31g of the product.

[0056] The synthesis yield of the crude product of PCS in this embodiment is 69.4%, and the yield of the final product (PCS-S1) is 64.4%, and its thermogravimetric (TGA) curve is shown in Figure 11 , It can be seen that the ceramic yield is 70.5%. The melting point of PCS-S1 is 235-250°C. Depend on Figure 8...

Embodiment 2

[0059] Experimental steps: (1) Vacuumize the atmospheric cracking rearrangement synthesis system, replace high-purity nitrogen, repeat 3 times; (2) under the protection of high-purity nitrogen, put the LPS (190g) of Preparation Example 1 into the reaction device In, then under stirring, add 0.38g of B (C 6 f 5 ) 3 Catalyst (0.20wt% of LPS); (3) temperature program, 23.5h to 395°C, and heat preservation reaction for 4h, the total reaction time is 27.5h; (6) then distilled at 370°C to remove low molecular weight; (7 ) was cooled to room temperature to obtain product (PCS-S2) 113.05g (yield 59.5%), and its ceramic yield was 70.5%.

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Abstract

The invention relates to a method for preparing polycarbosilane through cracking rearrangement of a cyclic silane compound or chain polysilane under the catalytic effect of trace (lower than 1wt%) boron-containing catalyst. According to the invention, polydimethylsilane (PDMS) or a pyrolysis product thereof which is a liquid-state silane-carbosilane compound (LPS) is adopted as a raw material; lower than 1wt% (relative to the amount of the raw material) of the boron-containing catalyst is added; the temperature is gradually increased to a reaction temperature under a normal pressure or a high pressure, such that a pyrolysis / rearrangement reaction is carried out, and solid-state polycarbosilane (PCS) with relatively high ceramic yield is obtained. The method provided by the invention has the advantages of short reaction time, high synthesis yield, good product quality, simple equipment and safe operation. The prepared polycarbosilane is a SiC precursor polymer, and can be used in the preparations of SiC fiber and SiC-based composite materials.

Description

technical field [0001] The invention relates to a synthesis method of a silicon carbide ceramic precursor polymer, in particular to a catalytic synthesis method for converting solid polydimethylsilane or its cracked product into polycarbosilane through pyrolysis-rearrangement. Background technique [0002] Ceramic matrix composites (CMC) have key and extensive applications in the fields of aviation, aerospace, weapons, ships, armor protection and high-speed braking. Silicon carbide (SiC)-based composite materials have a series of advantages such as high temperature resistance, high strength, high modulus, low density, and small thermal expansion coefficient, and have become a new generation of strategic thermal structural materials. [0003] The silicon carbide ceramic precursor polymer is the key raw material for the preparation of silicon carbide fibers, as the matrix resin for the preparation of silicon carbide-based composite materials by the PIP method, and for the fiel...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G77/60D01F9/10C04B35/565
Inventor 李永明杨潇淦徐彩虹贺丽娟
Owner INST OF CHEM CHINESE ACAD OF SCI
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