Photoresponsive Electrospun Fiber Meshes with Switchable Wettability for Effective Fog Water Harvesting in Variable Humidity Conditions

Abstract

The global water supply worsens yearly with climate change; therefore, the need for sustainable water resources is growing. One of them is fog water collectors with variable surface wettability, with multifunctional designs for utilization worldwide and to address regions with low humidity levels. Therefore, we created fiber meshes with a photoresponsive switchable surface. This study uses electrospun polyvinylidene fluoride (PVDF) meshes, whose wettability is controlled by adding TiO 2 . The fog water collection performance is studied at high and low humidity levels. With TiO 2 -PVDF, the electrospun mesh can be converted from hydrophobic to hydrophilic under UV irradiation and transformed back to a hydrophobic state with heat treatment. The switchable meshes were found to be more effective at water collection after UV irradiation at lower fog rates of 200 mL•h −1 . The ability to switch between hydrophobic and hydrophilic properties as needed is highly desired in fog collection applications using electrospun meshes, as it can improve overall efficiency after UV irradiation.

Unraveling the Impact of Boron Nitride and Silicon Nitride Nanoparticles on Thermoplastic Polyurethane Fibers and Mats for Advanced Heat Management

“…This can lead to poor processability, inferior mechanical properties, and increased cost. Therefore, controlling the spatial arrangement and orientation of fillers are key parameters to design composites with high thermal conductivity at lower filler loadings. − Electrospinning offers a versatile and scalable approach for producing composite fibers, meshes, and yarns in a single step. − It enables the addition of fillers in high loading percentages and enhances the filler distribution with controllable orientation along the axial direction of polymer fibers. , Moreover, the synergy of the applied electrical field and fillers’ organization during electrospinning improves the alignment of the polymer molecule chains, thereby augmenting the intrinsic thermal conductivity and Young’s modulus of the polymer matrix. − This enhancement in properties expands their applications in yarns, textiles, aerospace engineering, and biomedical devices. − Therefore, understanding the thermal properties of individual micro- and nanofibers is crucial for optimizing material performance and functionality, especially given the unique characteristics that emerge in low-dimensional nanostructures, such as size and temperature dependence of thermal conductivity, and internal phonon boundary and edge scatterings. , Scanning thermal microscopy (SThM) with excellent spatial resolution (<50 nm) and thermal sensitivity (<0.01 °C) stands out among methods for characterizing thermal properties, including materials’ thermal conductivity at the micro- and nanoscale. In this technique, a heated nanothermal tip contacts and scans the surface of the samples at room temperature, capturing and processing thermal feedback signals to derive local temperature distribution on the samples. − …”