title: Wetting Hierarchy in Oleophobic 3D Electrospun Nanofiber Networks.
abstract: Wetting behavior between electrospun nanofibrous networks and liquids is of critical importance in many applications including filtration and liquid-repellent textiles. The relationship between intrinsic nanofiber properties, including surface characteristics, and extrinsic nanofibrous network organization on resultant wetting characteristics of the nanofiber network is shown in this work. Novel 3D imaging exploiting focused ion beam (FIB) microscopy and cryo-scanning electron microscopy (cryo-SEM) highlights a wetting hierarchy that defines liquid interactions with the network. Specifically, small length scale partial wetting between individual electrospun nanofibers and low surface tension liquids, measured both using direct SEM visualization and a nano Wilhelmy balance approach, provides oleophobic surfaces due to the high porosity of electrospun nanofiber networks. These observations conform to a metastable Cassie-Baxter regime and are important in defining general rules for understanding the wetting behavior between fibrous solids and low surface tension liquids for omniphobic functionality.
authors.affiliation: §International Centre of Electron Microscopy for Materials Science and Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Al. A. Mickiewicza 30, 30-059 Kraków, Poland.
authors.forename: Urszula
authors.initials: U
authors.lastname: Stachewicz
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Bailey
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: Corinne A
authors.initials: CA
authors.lastname: Stone
authors.forename: Colin R
authors.initials: CR
authors.lastname: Willis
authors.affiliation: ⊥School of Engineering, University of Portsmouth, Portsmouth PO1 3DJ, United Kingdom.
authors.forename: Asa H
authors.initials: AH
authors.lastname: Barber
keywords: FIB-SEM tomography; cryo-SEM; electrospinning; polymeric nanofiber; wetting