A trash-to-treasure strategy to upcycle abandoned masks to ultraelastic fiber aerogel

Masks are indispensable in our daily life, but the accumulation of abandoned masks has been increasing in landfills and incineration, causing serious environmental concerns. Here, we propose a trash-to-treasure strategy to reuse the hard-to-degrade polypropylene (PP) fibers in abandoned masks and introduce polyvinyl alcohol (PVA) as a binder to fabricate ultralight and ultraelastic PP fiber aerogel through a facile freeze-drying process. The fiber aerogel exhibits a highly porous structure with PP fibers closely bonded by PVA. Thanks to the overlapping structure of the PP fibers and the bonding effect of PVA, the fiber aerogel shows ultraelastic properties and can undergo repeated compression without any fatigue. The results further indicate that the fiber aerogel represents selective wetting behavior to oil and water with water contact angle of ca. 130° and oil contact angle of 0°, respectively. Owing to the highly porous, ultraelastic, and special wetting behaviors, the fiber aerogel demonstrates diverse potential applications in oil/water separation, thermal insulation, and pressure sensing. Briefly, the fiber aerogels can absorb diverse kinds of oils and organic solvents with an optimal oil absorption capacity high up to 27.5 g/g. The fiber aerogel can also be used as a heat-insulating material to reduce heat loss. Further, after being modified by conductive filler, the fiber aerogel can monitor various human activities in real time, including walking, knee bending, sitting, and lying. This study not only provides a new way to alleviate the difficulties of recycling abandoned masks but also proposes a novel strategy to prepare value-added multifunctional fiber aerogels.