Work

Thermal Evolution of Silicon and Fluorine Species in Fluorosilane-Modified Carbon Aerogel Composites

Year: 2026

Type: article

Abstract: Carbon aerogels are widely used for thermal protection in extreme high-temperature environments under inert atmospheres because of their excellent thermal insulation. However, their high specific surface area and open-pore structure promote moisture uptake, necessitating hydrophobic or low-surface-energy functionalization for practical use. Existing studies have primarily focused on room-temperature wettability after modification, while the high-temperature decomposition of functional layers, elemental evolution, and volatile release remain insufficiently understood. Herein, vapor-phase fluorosilane (FAS)-modified carbon aerogel composites were investigated by combining solid-state chemical characterization with evolved-gas analysis to clarify the thermal evolution of the functional layer under inert high-temperature conditions. FAS modification produced a superhydrophobic surface with an initial water contact angle of approximately 163°. During heating, the FAS-derived functional layer entered a rapid-decomposition stage at approximately 372 °C, followed by the principal fluorinated-volatilization stage near 443 °C. Perfluoroalkyl-chain cleavage progressively removed fluorine from the material through the release of CxFy-containing volatile species, accompanied by the disappearance of C–F, CF2, and CF3 structures. In contrast, part of the silicon-containing fraction was retained and evolved into a Si–C-related residual structure. Although high-temperature exposure eliminated FAS-derived hydrophobicity, the nanoparticle-assembled nanoporous carbon framework remained intact without obvious structural collapse. These findings establish a selective thermal-failure pathway in which fluorinated chains preferentially decompose and volatilize, whereas silicon-containing species are partially retained and reconstructed on the carbon framework, clarifying the failure mechanism of surface-modified carbon aerogel nanomaterials in extreme thermal environments.

Source: Nanomaterials

DOI: 10.3390/nano16191250

Authors: Yiren Long, Junzong Feng, Yonggang Jiang, Yijie Hu, Jian Feng

Institution: National University of Defense Technology

Language: English

Topic: Aerogels and thermal insulation

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,896

Funders: National Natural Science Foundation of China, Natural Science Foundation of Hunan Province, Hunan University of Science and Technology