Stretchable and Superelastic Fibrous Sponges Tailored by "Stiff-Soft" Bicomponent Electrospun Fibers for Warmth Retention.

Health risks in an extremely cold environment make warm retention equipment highly desirable. However, creating materials with a high warm retention performance and robust mechanical property to durably prevent against the harsh conditions is highly challenging. Herein, we report on a one-step and facile strategy to fabricate stretchable and superelastic fibrous sponges by creating unique "stiff-soft" polymer networks within fibers and bonding architecture among fibers. The premise of this design is that stiff polystyrene can endow materials with rigidity and soft polyurethane can absorb energy during mechanical deformation. Benefiting from this systematic tailoring for the polymer and assembling networks, the resultant fibrous sponges exhibit a unique tensile recovery property, a large breaking elongation of 70%, and an outstanding resilience for resisting 100 cyclic compressions with 50% strain under -50 °C. Moreover, the fibrous sponges possess dramatic characteristics of high porosity (∼99.31%), ultralight property (volume density = 7.68 mg cm), and effective warmth retention (thermal conductivity = 27.6 mW m K), as well as technical features of the simple assembly process to scale up easily. The preparation of fibrous sponges provides a new vision for developing ultralight and efficient warmth retention materials.