Hydrophobic, Fire–Resistant, and Compressible Aramid Nanofiber Aerogels Enabled by In Situ Polysiloxane Cross-Linking

In this study, a mechanically robust, highly hydrophobic, and fire–resistant hybrid aerogel was developed using a green high–pressure homogenization process coupled with <i>in situ</i> polysiloxane cross-linking.

Through the construction of a rigid–flexible interpenetrating network, the resulting aerogel overcomes the inherent fragility associated with conventional physical entanglements while achieving an ultralow density of 4.62–9.48 mg cm^–3, pronounced superelasticity (96.7% height recovery and 79% modulus retention after 100 cycles), and excellent fire resistance (LOI = 33). Notably, the aerogel exhibits remarkable structural and functional integrity following combustion because <i>in situ</i> ceramization converts the polysiloxane network into a thermally stable Si–O–Si/Si–C barrier, enabling retention of 92% of its compressive strength while preserving substantial surface hydrophobicity, as evidenced by a water contact angle of 132.7° even after direct flame exposure.