Ultralight and Flame-Retardant Nanofiber/Aerogel Microfiber Sponges with Dual-Network Structures for Warmth Retention

Long-term exposure to cold conditions can cause damage to the body, which makes cold prevention equipment urgently needed. However, the most commonly used fibrous warmth retention materials have drawbacks of heavy weight, poor mechanical properties, flammability, and inefficient thermal insulating performance. Herein, we propose a simple and feasible strategy to prepare nanofiber/aerogel microfiber sponges (NAMS) with dual-network structures for warmth retention by direct electrospinning. The aerogel fibers are prepared by regulating the phase separation behavior of the jet, while flexible nanofibers are introduced between the aerogel fibers to construct dual-network structures in the sponge. The obtained NAMS is lightweight (3.44 mg cm^–3) and exhibits robust mechanical properties (almost no plastic deformation after enduring 500 stretching cycles and 1000 compression cycles), and efficient warmth retention properties (thermal conductivity of 23.92 mW m^–1 K^–1). Furthermore, the introduction of a flame retardant enables the NAMS to possess remarkable flame resistance, with a limiting oxygen index of 28.7%. The development of NAMS offers a promising avenue for future advancements in ultralight, flame-retardant, and high-efficiency warmth retention materials.