Abstract
Silsesquioxane (SQ) derivatives possessing intramolecular H2C = CH- groups and Si-H groups were designed as precursors for ternary silicon oxycarbide (SiOC). By using R-Si(OMe)3, H-Si(OEt)3 and (H-Si(Me)2)2O as starting compounds, SQ derivatives of VH-SQ (R = vinyl) and St-H-SQ (R = stylyl) were successfully synthesized through the conventional sol-gel route. Simultaneous thermogravimetric and mass spectroscopic analyses up to 1000 °C revealed that in situ cross-linking via hydrosilylation and demethanation of VH-SQ suppressed the evolution of gaseous hydrocarbon species to afford amorphous SiOC having a composition close to the desired stoichiometric SiO2(1−x)Cx (x = ca. 0.3) with a high yield. The effect of carbon content on the phase separation and crystallization of the SQ-derived amorphous SiOC was studied by several spectroscopic analyses and TEM observation. The results were discussed aiming to develop a novel polymer-derived ceramics (PDCs) route for in situ formation of binary β-SiC-amorphous SiO2 nanocomposites with enhanced thermal and mechanical stability.
Highlights
Increasing attention has been directed to organic–inorganic hybrid materials as promising functional materials in diverse fields such as optics, electronics, housing and energy
The chemical structures of VH-SQ and St-H-SQ were identified by the attenuated total reflection–infra red (ATR-IR) and 29 Si nuclear magnetic resonance (NMR)
These results revealed that VH-SQ and St-H-SQ had possessing a common main architecture study were converted to inorganic groups were eliminated during pyrolysis uppurification to 800 °C, the SQ derivatives synthesized with different compositions that was successfully synthesized as designed
Summary
Increasing attention has been directed to organic–inorganic hybrid materials as promising functional materials in diverse fields such as optics, electronics, housing and energy. The chemical composition of polymer-derived SiOC materials can be tetrahedral [7]. Carbon-rich silicon oxycarbides have oxycarbides have been synthesized [7,8,9] They exhibit an excellent thermal stability in terms of keeping been synthesized [7,8,9]. For improving the thermal and mechanical stability of SiC-amorphous SiO2 composites, it is. SiC-SiO2 composite (according to Equation (1) without excess carbon). 1.5C0.31 possessed a a composition with relatively low carbon content and was close to the SiC-SiO2 tie line (labeled as (B). In Figure 2),with resulting in thelow formation binary and β-SiC nanocrystallites finely dispersed amorphous. 2)—approximately two2(1−x) times higher compared with thosecontent of the (labeled previousas (B)S1and in Figure 2—was synthesized together with a reference material carbon-rich For the synthesis compositions of S1 and S2, silsesquioxane (SQ) derivatives which havereported intramolecular
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