Lightweight, Robust, and Superhydrophobic Multiscale Biomimetic Polymer Composites for Reusable Aerospace Thermal Protection

ABSTRACT Future reusable aerospace vehicles urgently demand thermal protection materials (TPMs) that combine low density, robust mechanical properties, exceptional thermal insulation, and repeatable ablation resistance under extreme high‐temperature oxidizing conditions, a formidable challenge. Inspired by the multiscale architecture of natural materials, we integrate a lightweight, rigid 3D carbon fiber fabric (CF), a nanoscale carbonizable phenolic resin (PR) aerogel, and a micron‐scale ceramicizable organosilicon (Si) skeleton into a ternary network via a facile sol–gel process followed by low‐temperature (100°C) chemical vapor deposition. The resulting CF/PR/Si composite achieves a remarkable synergy: low density (~0.3 g cm ⁻³ ), high strength/stiffness (11.32/574.18 MPa), intrinsic superhydrophobicity (water contact angle ~170°), and broad‐spectrum chemical resistance. Most critically, the composite exhibits remarkable repeatable ablation resistance, with a near‐zero linear ablation rate (0.17 μm s ⁻¹ ) and a backside temperature below 80°C after 10 cycles (cumulative 6000 s) of 1300°C butane flame exposure. This outstanding performance originates from synergistic protective mechanisms: in situ formation of a silicon‐containing ceramic barrier, transpiration cooling by pyrolysis gasses, efficient surface re‐radiation, and anisotropic heat regulation. Consequently, the CF/PR/Si composite represents a highly promising reusable TPM and a versatile bioinspired blueprint for advanced multifunctional composites in extreme environments.