Ultralight, Superelastic, and Washable Nanofibrous Sponges with Rigid-Flexible Coupling Architecture Enable Reusable Warmth Retention.

Nanofibrous sponges enable promising potentials in warmth retention but are impeded by short service life and nonwashability, owing to their inadequate mechanical properties. Herein, a scalable strategy is reported to develop ultralight, superelastic, and washable micro/nanofibrous sponges (MNFSs) with a rigid-flexible coupling architecture created by bridging high-modulus polyethylene terephthalate microfibers with flexible polyacrylonitrile nanofibers via robust bonding structures. Meanwhile, the in situ doping of fluoropolymer endows micro/nanofibers with desirable amphiphobicity. The resultant MNFSs present high resilience, superior compressive fatigue resistance (5.7% residual strain at 1000th), low-temperature-resistant superelasticity (up to -196 °C), and unique washing-invariant superelasticity. Moreover, the fascinating structures of high porosity, high tortuosity, and small pores enable MNFSs both ultralight property (7.5 mg cm -3 ) and effective warmth retention (28.51 mW m -1 K -1 ). Additionally, the MNFSs possess remarkable antifouling, robust stability, and long service life. The work might provide an avenue to develop mechanically robust nanofibrous sponges for various applications.