The Design and Preparation of a Novel Boron‐Containing Silicone Elastomer With High‐Temperature Resistance Based on a New Type of o‐Carborane Crosslinking Agent

ABSTRACT In this study, a novel boron‐containing silicone elastomer (TBEB) was successfully fabricated using an o‐carborane‐modified crosslinker (BTPW) synthesized via electrophilic bromination and Heck coupling reactions. Compared with conventional tetraethyl orthosilicate (TEOS) crosslinked silicone rubber, the TBEB series exhibited remarkable improvements in tensile strength, elongation, and thermal stability. The optimized sample (TBEB‐5) achieved a tensile strength of 1.45 MPa, an elongation of 467%, and a 17% increase in char yield relative to the control sample. Thermogravimetric analysis (TGA) revealed that the decomposition temperature (Td 5 ) of the TBEB series exceeded 408°C, while differential scanning calorimetry (DSC) confirmed enhanced chain rigidity and superior thermal resistance. Morphological characterization by scanning electron microscopy (SEM) and energy‐dispersive spectroscopy (EDS) indicated homogeneous dispersion of the crosslinker and a dense, well‐organized network structure. Furthermore, the TBEB elastomers exhibited outstanding high‐temperature aging resistance, maintaining 74% of their mechanical strength after 12 h at 200°C. Upon pyrolysis, the o‐carborane units promoted the formation of a dense Si–O–C/B–O–Si ceramic‐like network, improving ceramic yield and microstructural uniformity. Overall, this study provides an effective molecular design strategy for developing high‐performance, heat‐resistant silicone elastomers and polymer‐derived ceramics with excellent structural integrity and long‐term thermal stability.