ABSTRACT In this study, a novel carborane‐terminated silicon‐containing arylacetylene ceramic precursor (CPSA‐R) was successfully synthesized, employing dimethyldichlorosilane (DMDCS), methyldichlorosilane (MDCS), and methylvinyldichlorosilane (MVDCS) as silicon sources, with 1‐bromomethyl‐o‐carborane serving as the boron source and m‐diethynylbenzene as the crosslinking moiety. The molecular structure of the product was characterized and confirmed by Fourier transform infrared spectroscopy (FT‐IR) and proton nuclear magnetic resonance ( 1 H NMR). The curing mechanism, thermal stability, and ceramization behavior of the precursor were systematically investigated by x‐ray diffraction (XRD), thermogravimetric analysis (TGA), x‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Raman spectroscopy. The results demonstrate that the precursor exhibits excellent solubility, with curing predominantly governed by Si─C≡C crosslinking. Reactive substituents (such as Si─H and Si─CH═CH 2 ) significantly accelerate the Si─C≡C reaction and increase the crosslinking density, thereby effectively suppressing rupture of the carborane cage and leading to a ceramic yield exceeding 90% and enhanced thermal stability in TGA. XRD analysis revealed that the derived ceramics remain amorphous at 1200°C, initiate crystallization into SiC at 1400°C, and form a minor amount of B 4 C at 1600°C. SEM observations showed that with increasing pyrolysis temperature, grains evolve from dense amorphous structures to nearly spherical morphologies, with grain size following the order CPSA‐H > CPSA‐V > CPSA‐J. TEM further confirmed the presence of crystalline SiC and B 4 C in the pyrolyzed ceramics. XPS results indicated that the intensity ratios of Si─C/Si─O and B─C/B─O vary with crosslinking density, highlighting the pronounced influence of molecular structure on bond rearrangement, while also revealing that ceramization is jointly governed by carbothermal reduction and bond rearrangement reactions. Raman spectra further demonstrated that the degree of graphitization decreases with reduced carbon content in the side groups, with CPSA‐J exhibiting the highest graphitization. Thermal oxidation experiments showed that all three ceramics display a characteristic “weight‐gain followed by weight‐loss” trend upon heating in air. Among them, CPSA‐H exhibits the best oxidation resistance, attributable to its higher SiC and B 4 C content, which generate dense B 2 O 3 and SiO 2 protective layers during oxidation.
Feng et al. (Sun,) studied this question.