Ultralight, mechanically robust, and flame-retardant ultrafine fibrous sponges for high-performance warmth retention

The public health issues caused by low temperature have led to urgent demands on high-performance warmth retention materials to prevent heat loss of human body. Fiber materials, the most common warmth retention materials, always suffer from large weight, flammability and poor heat retention capacity. Here, we propose an effective strategy to fabricate flame-retardant and ultralight fibrous sponges (FUFSs) with mechanical robustness and remarkable warmth retention performance by humidity-induced electrospinning technology. Precisely tailoring the relative humidity leads to the construction of ultrafine fibrous sponges, while the flame retardance is achieved by introducing flame retardant. The resultant FUFSs exhibit ultralight property (density of 3.1 mg cm(-3)), mechanical robustness (similar to 0% plastic deformations after 1000 stretchable and compressive tests), desirable warmth retention performance (thermal conductivity of 23.3 mW m(-1) K-1), and flame retardance (limit oxygen index of 25.2%). This work may open a new way for developing mechanically robust and flame-retardant three-dimensional fibrous materials for various applications.