Preparation method of polycarbosilane

Abstract

The invention relates to the technical field of organosilicon and provides a preparation method of polycarbosilane in order to solve the problems in polycarbosilane preparation at present. The preparation method is characterized by taking chloromethyl chlorosilane as a raw material, synthesizing a polycarbosilane intermediate in an organic solvent and then preparing the polycarbosilane by using a reducing agent. The preparation method provided by the invention has the advantages that the operation is convenient, and the time is shortened; meanwhile, the number-average molecular weight of the prepared polycarbosilane is higher, and the demands of preparing an organic functional material can be met.

Description

technical field

[0001] The invention relates to the technical field of organosilicon, in particular to a preparation method of polycarbosilane. Background technique

[0002] Polycarbosilane (PCS) is an organic precursor widely used in the preparation of special fibers (such as SiC fibers) and composite ceramics. SiC fibers have high strength and high hardness, high thermal stability and oxidation resistance, and low thermal expansion. coefficient and low density, high temperature stability (chemical, microstructural and mechanical stability) of SiC fiber in inert and oxidizing environments, coupled with its excellent mechanical properties (high breaking strength, stiffness and low creep rate, etc.) Making SiC fibers the best alternative for the production of structural composites with a wide range of applications, ranging from heat exchangers and hot gas filters to power production and aerospace machinery components.

[0003] The most important synthetic method of PCS is th...

Examples

Embodiment 1

[0023] Place (96g, 4mol) metal magnesium powder, iodine particle 0.22mol in a three-necked round-bottomed flask of 1000mL that is equipped with a magnetic stirrer, a constant pressure dropping funnel, a reflux condenser, and an air guide device, under a nitrogen atmosphere, Inject 300 mL of benzotrifluoride, and add (chloromethyl)methyldichlorosilane (250 mL, 2.2 mol) dropwise into the reaction flask under nitrogen protection. After the dropwise addition, react at room temperature for 3 hours, then add sodium hydride (52.8 g, 2.2 mol) and react at room temperature for 5 hours. Then add 100mL dilute hydrochloric acid to quench the reaction, separate the layers, filter, wash the organic phase twice with distilled water and saturated brine, and dry over anhydrous sodium sulfate. After removing the solvent, a light yellow oil is obtained, which is heated at 150°C for 5 hours to obtain Milky white rubber-like solid polysiloxane 1.

[0024] The yield is 70% (M w / M n =1.3, M n =...

Embodiment 2

[0026] Place (96g, 4.4mol) metal magnesium powder and 0.11mol of iodine particles in a 1000mL three-necked round bottom flask equipped with a magnetic stirrer, a constant pressure dropping funnel, a reflux condenser, and a gas guide device, under a nitrogen atmosphere , inject 1000mL trifluorotoluene, under the protection of nitrogen, add (chloromethyl)methyldichlorosilane (250mL, 2.2mol) dropwise into the reaction flask. After the dropwise addition, react at room temperature for 3 hours, then add potassium hydride (88 g, 6.6 mol) and react at room temperature for 3 hours. Then add 100mL dilute hydrochloric acid to quench the reaction, separate the layers, filter, wash the organic phase twice with distilled water and saturated brine, and dry over anhydrous sodium sulfate. After removing the solvent, a light yellow oil is obtained, which is heated at 200°C for 3 hours to obtain Milky white rubber-like solid polysiloxane 2.

[0027] reducing agent. The yield is 72% (M w / M n...

Embodiment 3

[0029] Place (96g, 5mol) metal magnesium powder, iodine particle 0.33mol in a three-necked round-bottomed flask of 1000mL that is equipped with a magnetic stirrer, a constant pressure dropping funnel, a reflux condenser, and an air guide device, under a nitrogen atmosphere, Inject 2000 mL of benzotrifluoride, and add (chloromethyl)trichlorosilane (248 mL, 2.2 mol) dropwise into the reaction flask under nitrogen protection. After the dropwise addition, react at room temperature for 2 hours, then add sodium hydride (176 g, 4.4 mol) and react at room temperature for 5 hours. Then add 1000mL dilute hydrochloric acid to quench the reaction, separate the liquids, filter, wash the organic phase twice with distilled water and saturated brine, and dry over anhydrous sodium sulfate. After removing the solvent, a light yellow oil is obtained, which is heated at 250°C for 2 hours to obtain Milky white rubber-like solid polysiloxane 3.

[0030] The yield is 85% (M w / M n =1.4, M n =22,...

technical field

[0001] The invention relates to the technical field of organosilicon, in particular to a preparation method of polycarbosilane. Background technique

[0002] Polycarbosilane (PCS) is an organic precursor widely used in the preparation of special fibers (such as SiC fibers) and composite ceramics. SiC fibers have high strength and high hardness, high thermal stability and oxidation resistance, and low thermal expansion. coefficient and low density, high temperature stability (chemical, microstructural and mechanical stability) of SiC fiber in inert and oxidizing environments, coupled with its excellent mechanical properties (high breaking strength, stiffness and low creep rate, etc.) Making SiC fibers the best alternative for the production of structural composites with a wide range of applications, ranging from heat exchangers and hot gas filters to power production and aerospace machinery components.

[0003] The most important synthetic method of PCS is th...

Examples

Embodiment 1

[0023] Place (96g, 4mol) metal magnesium powder, iodine particle 0.22mol in a three-necked round-bottomed flask of 1000mL that is equipped with a magnetic stirrer, a constant pressure dropping funnel, a reflux condenser, and an air guide device, under a nitrogen atmosphere, Inject 300 mL of benzotrifluoride, and add (chloromethyl)methyldichlorosilane (250 mL, 2.2 mol) dropwise into the reaction flask under nitrogen protection. After the dropwise addition, react at room temperature for 3 hours, then add sodium hydride (52.8 g, 2.2 mol) and react at room temperature for 5 hours. Then add 100mL dilute hydrochloric acid to quench the reaction, separate the layers, filter, wash the organic phase twice with distilled water and saturated brine, and dry over anhydrous sodium sulfate. After removing the solvent, a light yellow oil is obtained, which is heated at 150°C for 5 hours to obtain Milky white rubber-like solid polysiloxane 1.

[0024] The yield is 70% (M w / M n =1.3, M n =...

Embodiment 2

[0026] Place (96g, 4.4mol) metal magnesium powder and 0.11mol of iodine particles in a 1000mL three-necked round bottom flask equipped with a magnetic stirrer, a constant pressure dropping funnel, a reflux condenser, and a gas guide device, under a nitrogen atmosphere , inject 1000mL trifluorotoluene, under the protection of nitrogen, add (chloromethyl)methyldichlorosilane (250mL, 2.2mol) dropwise into the reaction flask. After the dropwise addition, react at room temperature for 3 hours, then add potassium hydride (88 g, 6.6 mol) and react at room temperature for 3 hours. Then add 100mL dilute hydrochloric acid to quench the reaction, separate the layers, filter, wash the organic phase twice with distilled water and saturated brine, and dry over anhydrous sodium sulfate. After removing the solvent, a light yellow oil is obtained, which is heated at 200°C for 3 hours to obtain Milky white rubber-like solid polysiloxane 2.

[0027] reducing agent. The yield is 72% (M w / M n...

Embodiment 3

[0029] Place (96g, 5mol) metal magnesium powder, iodine particle 0.33mol in a three-necked round-bottomed flask of 1000mL that is equipped with a magnetic stirrer, a constant pressure dropping funnel, a reflux condenser, and an air guide device, under a nitrogen atmosphere, Inject 2000 mL of benzotrifluoride, and add (chloromethyl)trichlorosilane (248 mL, 2.2 mol) dropwise into the reaction flask under nitrogen protection. After the dropwise addition, react at room temperature for 2 hours, then add sodium hydride (176 g, 4.4 mol) and react at room temperature for 5 hours. Then add 1000mL dilute hydrochloric acid to quench the reaction, separate the liquids, filter, wash the organic phase twice with distilled water and saturated brine, and dry over anhydrous sodium sulfate. After removing the solvent, a light yellow oil is obtained, which is heated at 250°C for 2 hours to obtain Milky white rubber-like solid polysiloxane 3.

[0030] The yield is 85% (M w / M n =1.4, M n =22,...

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