Highly Efficient Wettability Control via Three-Dimensional (3D) Suspension of Titania Nanoparticles in Polystyrene Nanofibers

Electrospinning is a simple and highly versatile method for the large-scale fabrication of polymeric nanofibers. Additives or fillers can also be used to functionalize the nanofibers for use in specific applications. Herein, we demonstrate a novel and efficient way to fabricate super-hydrophobic to hydrophilic tunable mats with the combined use of electrospinning and electrospraying that may be suitable for mass production on the merits of rapid deposition. The tunable nanocomposite mats were comprised of hydrophobic polystyrene nanofibers and hydrophilic titania nanoparticles. When the electrical conductivity of the electrospinning solution was increased, the surface morphology of the mats changed noticeably from a bead-on-string structure to an almost bead-free structure. Polystyrene (PS)-titania nanocomposite mats initially yielded a static water contact angle as high as 140 degrees +/- 3 degrees. Subsequently exposing these mats with relatively weak ultraviolet irradiation (lambda = 365 nm, I = 0.6 mW/cm(2)) for 2 h, the unique 3D suspension of the photoactive titania nanoparticles maximized the hydrophilic performance of the mats, reducing the static water contact angle to as low as 26 degrees +/- 2 degrees. The tunable mats were characterized by scanning electron microscopy (SEM), static water contact angle (WCA) measurements, and energy-dispersive X-ray spectroscopy (EDX). Our findings confirmed that the tunable mats fabricated by the simultaneous implementation of electrospraying and electrospinning had the most efficient ultraviolet (UV)-driven wettability control in terms of cost-effectiveness. Well-controlled tunable hydrophobic and hydrophilic mats find potential applications in functional textiles, environmental membranes, biological sensors, scaffolds, and transport media.