Electrospinning superhydrophobic fibers using surface segregating end-functionalized polymer additives.

We describe here a facile route for the in situ modification of the surface properties of fibers produced by electrospinning polystyrene containing small quantities of compatible polymer additives, end-functionalized with 1–3 fluoroalkyl groups. Such additives undergo spontaneous surface segregation during the electrospinning process, resulting in fibers with low surface energy, fluorine-rich, superhydrophobic surfaces. Surface properties were analyzed using static contact angle measurements (with water as the contact fluid) and X-ray photoelectron spectroscopy. We report the effect of a number of parameters on the surface properties of the resulting polystyrene fibers including the molecular weight and concentration of functionalized additive, the number of fluoroalkyl groups, the effect of annealing, and spinning solvent. The majority of the fibers were successfully produced using THF as the spinning solvent and fibers with a contact angle of ∼150° were attainable. However, preliminary investigations using a blend of polystyrene and 4 wt % of such an additive, end-functionalized with 3 C8F17 groups in a mixed solvent of DMF/THF (3:1 v/v), resulted in a mat of fibers with a superhydrophobic surface and a contact angle of 158°