Novel liquid polycarbosilane as well as preparation method and application thereof

A polycarbosilane and liquid technology, applied in the field of materials, can solve the problems of reduced impregnation efficiency, smaller porosity, high ceramic yield, etc., to achieve the effect of reducing porosity, reducing content, and increasing ceramic yield

Active Publication Date: 2014-12-03
淄博市临淄齐泉工贸有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although compared with PCS prepared by the classic Yajima method, perhydropolycarbosilanes modified with reactive groups such as vinyl and allyl groups have low impregnation efficiency in the preparation of SiC-based composites by the PIP method due to their low viscosity and high ceramic yield. However, there is still an urgent need for innovative solutions in terms of how to further improve its storage stability, inhibit curing and foaming, and how to reduce the impregnation efficiency due to the decrease in the porosity and pore size of the composite material in the later stage of the PIP processing cycle. technical approach to

Method used

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  • Novel liquid polycarbosilane as well as preparation method and application thereof
  • Novel liquid polycarbosilane as well as preparation method and application thereof
  • Novel liquid polycarbosilane as well as preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] A dry 1L three-necked round-bottomed flask is connected with a mechanical stirrer, a reflux condenser, a constant pressure dropping funnel and a gas guiding device, and then evacuated to replace nitrogen three times, while baking with a heat gun to remove attached water vapor. Under a nitrogen atmosphere, add 5.0 g of magnesium chips into the reaction flask, then add 4 mL of tetrahydrofuran, and heat to 30°C. A mixed solution of 2.97 g of chloromethyltriethoxysilane and 2 mL of tetrahydrofuran was added to the constant pressure dropping funnel, and slowly added dropwise to the reaction flask to initiate the Grignard reaction. Add a mixed solution of 59.17g of chloromethyltriethoxysilane and 150mL of tetrahydrofuran into the constant pressure dropping funnel, add it dropwise into the above reaction system at an appropriate speed under stirring, and keep the reaction at 30°C for 4h. Then, 69.0 g of vinylmagnesium bromide (1.6 mol / L) in methyl tetrahydrofuran was added thr...

Embodiment 2

[0053] A dry 1L three-necked round-bottomed flask is connected with a mechanical stirrer, a reflux condenser, a constant pressure dropping funnel and a gas guiding device, and then evacuated to replace nitrogen three times, while baking with a heat gun to remove attached water vapor. Under a nitrogen atmosphere, add 19.2 g of magnesium chips into the reaction flask, then add 30 mL of 2-methyltetrahydrofuran, and heat to 50°C. A mixed solution of 1.20 g of chloromethyltrimethoxysilane and 2-methyltetrahydrofuran (2 mL) was added to a constant pressure dropping funnel, and slowly added dropwise to the reaction flask to initiate a Grignard reaction. Add 67.1g of chloromethyltrimethoxysilane (0.4mol) and 170mL of 2-methyltetrahydrofuran mixed solution into the constant pressure dropping funnel, add it dropwise to the above reaction system at an appropriate speed under stirring, at 50°C Insulation reaction 6h. Then, 40 g of allyl bromide (0.33 mol) was slowly added through a const...

Embodiment 3

[0056] A dry 500mL three-necked round-bottomed flask is connected with a mechanical stirrer, a reflux condenser, a constant pressure dropping funnel and a gas guiding device, then evacuated and replaced with nitrogen three times, and at the same time baked with a heat gun to remove attached water vapor. Under a nitrogen atmosphere, quickly add 12.9 g of magnesium chips into the reaction flask, then add 15 mL of ethylene glycol dimethyl ether and 1-2 iodine crystals, and heat at 70° C. for five minutes. Add a mixed solution of 100g of chloromethyltriethoxysilane (0.47mol) and 200mL of ethylene glycol dimethyl ether into the constant pressure dropping funnel, and slowly add 1-3% to the reaction flask to initiate the Grignard reaction . After confirming the initiation, stir, and drop the mixed solution into the above reaction system at an appropriate speed, and keep the reaction at 70° C. for 8 hours. Then, 250 mL of tetrahydrofuran solution of vinylmagnesium chloride (2.0 mol / L...

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Abstract

The invention discloses novel liquid polycarbosilane which is low in viscosity and high in storage stability and is crosslinkable, a preparation method of novel liquid polycarbosilane, and an application of novel liquid polycarbosilane. Polycarbosilane is prepared by adopting chloromethyl alkoxy silane or mixtures of chloromethyl alkoxy silane as raw materials by virtue of Grignard coupling reaction and reduction reaction, and the structure of polycarbosilane is shown in a formula (I) in the specification. The structure simultaneously contains Si-H bonds and unsaturated bonds such as C=C bonds, can be subjected to self-crosslinking and curing under a certain condition, has relatively high ceramic yield, and can be used as a silicon carbide precursor of a polymer precursor impregnation pyrolysis (PIP) process. Polycarbosilane disclosed by the invention is adjustable in structural composition, good in storage stability, low in viscosity and relatively low in boiling point, and has the utilization potentiality of being used as a silicon carbide ceramic precursor for chemical vapor deposition/chemical vapor infiltration (CVD/CVI). In addition, polycarbosilane can also be used for replacing commonly-used divinyl benzene to serve as a crosslinking agent of solid-state polycarbosilane (PCS).

Description

technical field [0001] The invention relates to a novel liquid polycarbosilane and a preparation method thereof, and belongs to the field of materials such as silicon carbide ceramic precursors and carbosilane high temperature resistant resins. Background technique [0002] Silicon carbide (SiC) ceramic matrix composites have excellent properties such as high temperature resistance, low density, high strength, high modulus, thermal shock resistance and radiation resistance. They are a new generation of strategic thermal structural materials and have been widely used in aerospace, Space technology, energy, chemical industry, transportation and other fields. The main preparation methods include polymer precursor impregnation pyrolysis (PIP), reactive melt infiltration (RMI), chemical vapor infiltration (CVI), CVI+PIP, CVI+RMI and other methods. In the CVI process, the commonly used precursor is methyltrichlorosilane. During the production process, it will release HCl gas to ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G77/60C04B35/565
Inventor 李永明贺丽娟徐彩虹焦玲玲
Owner 淄博市临淄齐泉工贸有限公司
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