(65at) Micro-Scale Effects On the Wettability of Electrospun PVP-Titania Fiber Mats On ITO Substrates in Aqueous Media

Nanowires have been produced in dense mats by electrospinning a solution of dispersed polyvinylpyrrolidone (PVP) and a titania precursor onto indium tin oxide (ITO) plates. Parameters affecting the wettability of these mats are under investigation, including contact angle dynamics, mat segment density, spinning and curing conditions, and micro-scale fluid interactions with the wire mats. Mats that were spun at a short distance for contact times of 30 seconds, one minute, and three minutes indicate that the hydrophilic properties of the mat increase with mat thickness. Contact angles as high as 150° were measured, but there was not a distinct pattern in contact angles within a single specimen set. Dynamics of the contact angle measurement indicate that placement of a water droplet onto samples must be done carefully to retain high contact angles. If the droplet is dropped onto the mat surface from a height of 1.5 cm, the hydrophilic properties were shown to decrease the contact angles as much as 38° due to micro-scale wetting of the wire network. Future work will include counting the number of wire intersections within a segment of a sample to determine a segment density and determine a relationship between microscopic configuration and wettability characteristics.