Advanced, universal, and facile gel spinning-based aerogel fibrillation: in situ fabrication of highly stretchable TPU-silica hybrid network in ambient conditions

Innovations in synthesis and processing are critical for making high-performance aerogel fibers. Here, we present a novel method for creating highly stretchable aerogel fibers with exceptional thermal insulation. This innovative approach involves flow-assisted orientation and a dual-crosslinking strategy within a gel spinning system, all achievable in ambient conditions. Trimethoxy silane propyl isocyanate (TEPI) was grafted onto thermoplastic polyurethane (TPU) to create TPU-g-TEPI. This modified TPU (mTPU) is then dissolved in dioxane at varying concentrations while incorporating finely ground silica aerogel (SA) as a thickening agent. Rheological analysis confirms the formation of a physically entangled network of TPU and SA particles, displaying a significant increase in viscosity and yield stress. The resulting crosslinked hybrid network demonstrates thermal and mechanical robustness, with a highly porous structure, hierarchical morphology, and improved thermal stability. The mesoporous nature of the silica aerogel significantly reduces thermal conductivity to 0.024 W·m⁻¹·k⁻¹ and enhances thermal stability up to 400 °C. While crosslinked TPU nanofibers exhibit tensile stress and strain of 10.26 MPa and 100.94%, respectively, these mechanical properties remained stable over a broad temperature range from −60 to 150 °C. This study also offers fundamental insights into the currently unknown fatigue behavior of aerogel fibers, serving as a starting point for dynamic reliability evaluations. The versatile gel spinning technique holds great promise for revolutionizing high-performance aerogel fiber production. These advanced fibers hold significant prospects for diverse applications, including protective clothing and stretchable apparel, particularly in harsh environments.