Water resources are shrinking year by year, and fog water collectors (FWCs) are already being used in humid regions, where populations have limited access to traditional water resources. The aim of this study was to use electrospun fibers as FWCs to collect water. Two polymers with different wetting and mechanical properties were successfully combined to create a Janus structure from hydrophobic polystyrene (PS) and hydrophilic cellulose acetate (CA). These fibers, with a specially designed gutter shape, were electrospun using a side-nozzle system. The resulting side-by-side PS-CA fiber meshes proved to be a more effective system for fog collection under controlled laboratory conditions than either commercially available Raschel mesh or PS and CA fibers alone. The efficiency of Janus PS-CA fiber mesh achieved a rate of 71 mg·cm–2·h–1. The reinforcement of PS with CA made it possible to obtain durable and mechanically stable PS-CA meshes with higher tensile strength than PS or CA fiber mesh alone. These new PS-CA Janus fibers proved to be a robust and highly efficient system for water harvesting applications.

Sponges based on short electrospun fibers have received significant attention due to their ultrahigh porosity, lightweight, and multifunctional characteristics. In particular, polyimide (PI) sponges have been researched due to their exceptional mechanical properties and thermal stability. Nevertheless, a number of sponges, including PI, are usually hydrophobic and synthesized in toxic, nonwater solvents (e.g., 1,4-dioxane). Conversely, hydrophilic sponges disintegrate upon contact with water. Here, we suggest a new strategy to fabricate PI sponges in water by introducing a suitable surfactant, sodium dodecylbenzenesulfonate (SDBS) (sPI sponges). With less than 1 wt % of SDBS with respect to PI short fibers, they can be homogeneously dispersed in water and mixed well with poly­(amic acid) (PAA) solution. The synthesized sponge, depending on the concentration of SDBS, showed hydrophilic properties and substantial water uptake above 5000%. The hydrophilic properties of the sponges, which are not common, and the preparation from aqueous solution introduce new research opportunities. Such hydrophilic sponges are particularly special because they do not swell in contact with water, which makes them dimensionally stable. The methods presented here can serve as a milestone for the future development of various kinds of hydrophilic sponges applied for various applications, ranging from tissue engineering to oil/water separation.

Materials with an extremely low thermal and high electrical conductivity that are easy to process, foldable, and nonflammable are required for sustainable applications, notably in energy converters, miniaturized electronics, and high-temperature fuel cells. Given the inherent correlation between high thermal and high electrical conductivity, innovative design concepts that decouple phonon and electron transport are necessary. We achieved this unique combination of thermal conductivity 19.8 ± 7.8 mW/m/K (cross-plane) and 31.8 ± 11.8 mW/m/K (in-plane); electrical conductivity 4.2 S/cm in-plane in electrospun nonwovens comprising carbon as the matrix and silicon-based ceramics as nano-sized inclusions with a sea-island nanostructure. The carbon phase modulates electronic transport for high electrical conductivity, and the ceramic phase induces phonon scattering for low thermal conductivity by excessive boundary scattering. Our strategy can be used to fabricate the unique nonwoven materials for real-world applications and will inspire the design of materials made from carbon and ceramic.

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