Robust and Thermally Stable Silicone Aerogels with Hyperconnected Network via Kinetically Optimized Hyperbranched Silane Precursors

ABSTRACT The development of high‐performance silicone aerogels is often limited by a trade‐off between mechanical strength and thermal stability. Distinct from the stochastic co‐polymerization of traditional networks that yield heterogeneous structures, we present a kinetic‐control strategy enabling the precise construction of a robust and thermally stable silicone aerogel (PSA) with a hyperconnected network. This is achieved by co‐condensing novel hyperbranched siloxane‐amino/epoxy (SAE) nodes with linear polymethylhydrosiloxane (PMS). The hyperbranched SAE is formed through temperature‐regulated polycondensation exploiting the kinetic disparity between methoxy‐ and ethoxy‐silane precursors, which is hypothesized to direct the reaction toward intermolecular crosslinking while suppressing intramolecular cyclization. This ensures uniform incorporation of flexible segments and abundant reactive sites. Subsequent co‐condensation yields a highly crosslinked framework with embedded flexible segments, providing superior mechanical strength and thermal stability with minimal organic content. The optimized PSA exhibits high compressive strength (7.1 MPa), low density (0.32 g·cm − 3 ), low thermal conductivity (0.032 W·m − 1 ·K − 1 ), and high char yield (68% at 800°C). The quartz‐fiber composite (PSC) achieves high tensile strength (28.1 MPa) and excellent thermal‐insulation and ablation resistance up to 1000°C. This reactivity‐programmed assembly establishes a new paradigm for decoupling strength and thermal stability in hybrid aerogels.