Synthesis of transparent electrospun composite nanofiber membranes by asymmetric solvent evaporation process

Currently, transparent and flexible electrospun nanofiber membranes have attracted considerable attention due to their potential use in electronic displays, solar cells, air filtration, and medical and health fields (i.e., transparent wound dressings). Developing transparent nanofibrous membranes is still very intriguing because of severe light reflection and absorption into the fibrous membranes. Herein, we report a successful fabrication technique of transparent composite nanofibrous membranes by combining electrospinning and a particular post-treatment of the prepared membranes. Firstly, randomly organized polyurethane (PU) nanofibers were prepared via electrospinning. These PU nanofibers mats were then impregnated into different concentrations (i.e., 5, 10, and 15 wt%) and embedded time (i.e., 30 and 60 min) of poly (methyl methacrylate) (PMMA) and polydimethylsiloxane (PDMS) solutions to prepare transparent composite nanofibrous membrane using solution immersion technique. The resulting composite nanofibrous membranes exhibit excellent performance, including optical transparency (i.e., up to 82% for PMMA and similar to 6% for PDMS), lacking affinity to water, mechanically robust, reasonable water vapor transmission rate (WVTR, similar to 1 kg/m(2) day), and good thermal stability. The composite nanofiber membranes have promising optical transparency, suitable mechanical strength, and high hydrophobicity. Therefore, they have the potential in various applications, including windshields for highly moving objects, displays, and particularly as transparent wound dressings in medicine.