Ultralight and extra-soft fiber sponge with “marshmallow- shape” fabricated by layer-by-layer self-assembly electrospinning method

Electrospinning is an effective way to prepare two-dimensional nanofiber membranes. However, it is difficult to increase the thickness of the film by simply increasing the spinning time, thus limiting the potential applications of electrospinning. In this paper, we present a simple and stable method for preparing three-dimensional “marshmallow-shape” fiber sponges. By adding urea to the polyacrylonitrile polymer spinning solution, the humidity response of the nanofibers in the electrospinning environmental field could be enhanced, speeding up the hardening process of the nanofibers and forming a three-dimensional structure. The resulting three-dimensional “marshmallow-shaped” fiber sponge has a low bulk density (0.9 mg/cm3), good compression recovery, and good hydrophobicity (WCA = 135.6°). Moreover, good compression recovery after carbonization could be achieved by maintaining its original thickness, as well as with a strong oil-based organic solvent adsorption capacity.