Superelastic, ultralight, and washable electrospun fibrous sponges for effective warmth retention

Ultrafine fibrous sponges with efficient heat retention capability enable applications in various fields but are hindered due to their poor washability and weak mechanical properties. Here, we develop high-performance electrospun fibrous sponges with superelasticity, washable durability, and effective warmth retention performance by combining direct electrospinning and post-imidization treatment. The incorporation of mechanically robust polyimide and the low surface energy fluorinated polyurethane imparts the fluffy sponges with desired structural stability and high hydrophobicity. Significantly, the obtained sponges exhibit robust resilience (∼4% plastic deformation after 100 compressive cycles), ultralight property (3.6 mg cm−3), effective thermal retention with thermal conductivity of 25.5 mW m−1 K−1, and outstanding washability with maintaining almost unchanged structures and performances after cyclic washing. The successful synthesis of such intriguing fibrous sponges could serve as a guide for designing the next-generation washable warmth retention materials.