Synthesis and properties of a new, branched polyhydridocarbosilane as a precursor for silicon carbide

Froehling, Peter E.

doi:10.1007/bf00683932

Cited by 27 publications

(34 citation statements)

References 13 publications

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“…Thus, TGA was used to study the thermal behavior and mass residue of PHPCS during the heat-treatment process. Froehling 4 reported that a previous crosslinking treatment before pyrolysis could improve the final ceramic yield of a branched PCS. The liquid PHPCSs were crosslinked at 170 C for 6 h under an argon atmosphere to gain compact yellow solids, and then, the solids were used for TGA (Fig.…”

Section: Thermal Properties Of Phpcsmentioning

confidence: 99%

“…In our previous study, oxygen-containing units, such as SiAO(CH 2 ) 4 ASi and SiAO(CH 2 ) 4 ACl, were introduced into AHPCS and EHPCS because of the side reaction. This was confirmed by the 1 H-NMR results, in which multiplets ranging from 1.5 to 2 ppm assigned to the methylene protons of SiOCH 2 CH 2 CH 2 CH 2 segments derived from THF were observed.…”

Section: Synthesis and Characterization Of Phpcsmentioning

confidence: 99%

“…3 In a previous study, we investigated the side reactions of THF solvent and SiACl bonds in chlorosilanes in detail. 12 It is supposed that oxygen-containing units, such as SiAO(CH 2 ) 4 ASi and SiAO(CH 2 ) 4 ACl, are introduced into AHPCS and EHPCS because of the side reaction. Therefore, in this study, Cl 3 SiCH 2 Cl was partially methoxylated to reduce the amount of active SiACl bonds; this was expected to inhibit the side reaction.…”

Section: Synthesis and Characterization Of Phpcsmentioning

confidence: 99%

“…The resulting solution was reduced by 9.6 g of LiAlH 4 (0.25 mol, 30% excess) with ice-water cooling under rapid stirring, and then, the resultant suspension was stirred under argon for 12 h at 60 C again.…”

Section: Aqueous Workupmentioning

confidence: 99%

“…Recently, a liquid hyperbranched PCS has been studied extensively as a promising precursor to SiC because of its ideal processing and stoichiometric C/Si ratio; its study has involved the synthesis, modification, and polymer-to-ceramic conversion of this PCS. [3][4][5][6][7][8][9][10] In a previous study, we successfully synthesized a hyperbranched allyhydridopolycarbosilane (AHPCS) by a one-pot synthesis with chloromethyltrichlorosilane (Cl 3 SiCH 2 Cl), chloromethylmethyldichlorosilane [Cl 2 Si(CH 3 )CH 2 Cl], and allyl chloride as the starting materials, and we could control the composition of this AHPCS by controlling the amounts of the starting materials. 11,12 Subsequently, the polymer-toceramic conversion of this AHPCS for SiC-based ceramics was further studied.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of a propargyl‐substituted polycarbosilane with high ceramic yield

Zhan

et al. 2011

J of Applied Polymer Sci

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A propargyl-substituted polycarbosilane (PCS), namely, propargyl-substituted hyperbranched hydrodipolycarbosilane (PHPCS), was prepared by a modified synthesis route, which involved Grignard coupling of partially methoxylated Cl 3 SiCH 2 Cl and CHBCCH 2 Cl, followed by reduction with lithium aluminum hydride. The resultant PHPCSs were characterized by gel permeation chromatography, Fourier transform infrared (FTIR) spectroscopy, and NMR. Moreover, the thermal properties of the PHPCSs were investigated by thermogravimetric analysis. The ceramic yield of PHPCS at 1400 C was about 82.5%, which was about 10 wt % higher than that of hyperbranched hydrodipolycarbosilane without the substitution of propargyl groups. The PHPCS-derived ceramics were characterized by X-ray diffraction (XRD), FTIR spectroscopy, and elemental analysis. The XRD and FTIR results indicate that the heat treatment significantly influenced the evolution of crystalline b-SiC. It can be convenient to get near-stoichiometric ceramics from PHPCS through the control of feed ratios of the starting materials.

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Section: Thermal Properties Of Phpcsmentioning

confidence: 99%

Section: Synthesis and Characterization Of Phpcsmentioning

confidence: 99%

Section: Synthesis and Characterization Of Phpcsmentioning

confidence: 99%

Section: Aqueous Workupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of a propargyl‐substituted polycarbosilane with high ceramic yield

Zhan

et al. 2011

J of Applied Polymer Sci

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Synthesis and properties of liquid polycarbosilanes with hyperbranched structures

Huang

Fang

et al. 2009

J of Applied Polymer Sci

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Liquid polycarbosilanes substituted by unsaturated groups were prepared by a one-pot synthesis with Cl 2 Si(CH 3 )CH 2 Cl, Cl 3 SiCH 2 Cl, and CH 2 ¼ ¼CHCH 2 Cl (or HCBCMgBr) as the starting materials. The as-received polycarbosilanes were characterized by gel permeation chromatography, Fourier transform infrared spectroscopy, and nuclear magnetic resonance and were confirmed to have hyperbranched structures. The polymer yield, SiAH content, side reaction, unsaturated group content, and polymer structure are affected by the amount of the starting materials in feed. The thermal properties of the polycarbosilanes were investigated by thermogarvimetric analysis. The ceramic yield of allyhydridopolycarbosilane is about 60% and that of ethynylhydridopolycarbosilane is over 75%, indicating that the liquid polycarbosilanes have great potential to be promising precursors to SiC. Moreover, the compositions of the polycarbosilanes and the final ceramics can be tailored by controlling the amount of the starting materials.

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Preparation of a liquid boron‐modified polycarbosilane and its ceramic conversion to dense SiC ceramics

Fang

Huang

et al. 2011

Polymers for Advanced Techs

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A boron-modified ethynylhydridopolycarbosilane (B-EHPCS) was successfully prepared via the hydroboration reaction of ethynylhydridopolycarbosilane (EHPCS) with 9-borabicyclo-[3.3.1]nonane (9-BBN). The as-synthesized B-EHPCS with a branched structure was characterized by means of gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). The structural evolution of ceramic conversion of B-EHPCS was investigated by solid-state NMR. The (13)C magic angle spinning (MAS) NMR results indicated that the C=C and C C groups of B-EHPCS take part in the hydrosilation cross-linking at a relatively low temperature (170 degrees C). According to the (29)Si MAS NMR analysis, the CSiH(3) end groups are most reactive hydride functionality involved in the hydrosilation cross-linking. With increasing curing temperature, the C(2)SiH(2) and CSiH(3) units are completely consumed, while C(3)SiH units remain even after curing at 600 degrees C. The TGA results show the 1200 degrees C ceramic yield of B-EHPCS reaches 86%, which is 10% higher than that of the parent EHPCS (76%). At high temperatures, the introduction of <1 wt% boron significantly inhibits silicon carbide (SiC) crystallization. The 1800 degrees C ceramics derived from B-EHPCS are found to be significantly denser than that from EHPCS. Copyright (C) 2010 John Wiley & Sons, Ltd.National Natural Science Foundation of China[50802079, 20925208, 50532010]; Natural Science Foundation of Fujian Province of China[2008J0165

show abstract

Synthesis and properties of a new, branched polyhydridocarbosilane as a precursor for silicon carbide

Cited by 27 publications

References 13 publications

Synthesis and characterization of a propargyl‐substituted polycarbosilane with high ceramic yield

Synthesis and characterization of a propargyl‐substituted polycarbosilane with high ceramic yield

Synthesis and properties of liquid polycarbosilanes with hyperbranched structures

Preparation of a liquid boron‐modified polycarbosilane and its ceramic conversion to dense SiC ceramics

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